A modem – a portmanteau of "modulator-demodulator" – is a hardware device that converts data from a digital format, intended for communication directly between devices with specialized wiring, into one suitable for a transmission medium such as telephone lines or radio. A modem modulates one or more carrier wave signals to encode digital information for transmission, and demodulates signals to decode the transmitted information. The goal is to produce a signal that can be transmitted easily and decoded reliably to reproduce the original digital data.
Modems can be used with almost any means of transmitting analog signals, from light-emitting diodes to radio. A common type of modem is one that turns the digital data of a computer into a modulated electrical signal for transmission over telephone lines, to be demodulated by another modem at the receiver side to recover the digital data.
Modems are frequently classified by the maximum amount of data they can send in a given unit of time, usually expressed in bits per second (symbol bit/s, sometimes abbreviated "bps") or rarely in bytes per second (symbol B/s). Modern broadband modems are typically described in megabits.
Historically, modems were often classified by their symbol rate, measured in baud. The baud unit denotes symbols per second, or the number of times per second the modem sends a new signal. For example, the ITU V.21 standard used audio frequency-shift keying with two possible frequencies, corresponding to two distinct symbols (or one bit per symbol), to carry 300 bits per second using 300 baud. By contrast, the original ITU V.22 standard, which could transmit and receive four distinct symbols (two bits per symbol), transmitted 1,200 bits by sending 600 symbols per second (600 baud) using phase-shift keying.
Many modems are variable-rate, permitting them to be used over a medium with less than ideal characteristics, such as a telephone line that is of poor quality or is too long. This capability is often adaptive so that a modem can discover the maximum practical transmission rate during the connect phase, or during operation.
A dial-up modem transmits computer data over an ordinary telephone line that has not been designed for data use. Other modem technologies (such as leased line modems) operate over lines that are often provided by a telephone company, but are intended for data use and do not impose the same signaling constraints.
The modulated data must fit the frequency constraints of a normal voice audio signal, and the modem must be able to perform the actions needed to connect a call through a telephone exchange, namely: picking up the line, dialing, understanding signals sent back by phone company equipment (dialtone, ringing, busy signal,) and on the far end of the call, the second modem in the connection must be able to recognize the incoming ring signal and answer the line.
Dial-up modems have been made in a wide variety of speeds and capabilities, with many capable of testing the line they're calling over and selecting the most advanced signaling mode that the line can support. Generally speaking, the fastest dialup modems ever available to consumers never exceeded 56 KiB/s, and never achieved that speed in both directions.
The dial-up modem was once a widely known technology, since it was mass-marketed to consumers in many countries for dial-up internet access. In the 90s, tens of millions of people in the United States used dial-up modems for internet access.
Dial-up service has since been largely supplanted by broadband internet, which typically still uses a modem, but of a very different type which may still operate over a normal phone line, but with substantially relaxed constraints.
News wire services in the 1920s used multiplex devices that satisfied the definition of a modem. However, the modem function was incidental to the multiplexing function, so they are not commonly included in the history of modems. Modems grew out of the need to connect teleprinters over ordinary phone lines instead of the more expensive leased lines which had previously been used for current loop–based teleprinters and automated telegraphs.
In 1941, the Allies developed a voice encryption system called SIGSALY which used a vocoder to digitize speech, then encrypted the speech with one-time pad and encoded the digital data as tones using frequency shift keying.
Mass production of modems in the United States began as part of the SAGE air-defense system in 1958 (the year the word modem was first used), connecting terminals at various airbases, radar sites, and command-and-control centers to the SAGE director centers scattered around the United States and Canada. SAGE modems were described by AT&T's Bell Labs as conforming to their newly published Bell 101 dataset standard. While they ran on dedicated telephone lines, the devices at each end were no different from commercial acoustically coupled Bell 101, 110 baud modems.
The advent of metal–oxide–semiconductor field-effect transistor (MOSFET) technology, integrated circuit chips and shift register MOS memory led to the application of solid-state microelectronic semiconductor technology and digital circuitry to the implementation of digital multi-channel modems in the 1960s. This enabled advantages such as a very small size, light weight, stability, high reliability, low cost, and freedom from adjustment.
The 201A and 201B Data-Phones were synchronous modems using two-bit-per-baud phase-shift keying (PSK). The 201A operated half-duplex at 2,000 bit/s over normal phone lines, while the 201B provided full duplex 2,400 bit/s service on four-wire leased lines, the send and receive channels each running on their own set of two wires.
The Bell 103A dataset standard was also introduced by AT&T in 1962. It provided full-duplex service at 300 bit/s over normal phone lines. Frequency-shift keying was used, with the call originator transmitting at 1,070 or 1,270 Hz and the answering modem transmitting at 2,025 or 2,225 Hz. The readily available 103A2 gave an important boost to the use of remote low-speed terminals such as the Teletype Model 33 ASR and KSR, and the IBM 2741. AT&T reduced modem costs by introducing the originate-only 113D and the answer-only 113B/C modems.
While Bell (AT&T) provided modems that attached via direct wire connection to the phone network as early as 1958, their regulations at that time did not permit the direct electrical connection of any non-Bell device to a telephone line. However, the Hush-a-Phone ruling allowed customers to attach any device to a telephone set as long as it did not interfere with its functionality. This allowed third-party (non-Bell) manufacturers to sell modems utilizing an acoustic coupler.
With an acoustic coupler, an ordinary telephone handset was placed in a cradle containing a speaker and microphone positioned to match up with those on the handset. The tones used by the modem were transmitted and received into the handset, which then relayed them to the phone line.
Because the modem was not electrically connected, it was incapable of picking up, hanging up or dialing, all of which required direct control of the line. Touch-tone dialing would have been possible, but touch-tone was not universally available at this time. Consequently, the dialing process was executed by the user lifting the handset, dialing, then placing the handset on the coupler.
Throughout the 1970s, acoustically coupled modems compatible with the Bell 103A de-facto standard were commonplace. Well-known models included the Novation CAT and the Anderson-Jacobson. A lower-cost option was the Pennywhistle modem, designed to be built using parts from electronics scrap and surplus stores.
In December 1972, Vadic introduced the VA3400, notable for full-duplex operation at 1,200 bit/s over the phone network. Like the 103A, it used different frequency bands for transmit and receive.
In November 1976, AT&T introduced the 212A modem to compete with Vadic. It was similar in design, but used the lower frequency set for transmission. One could also use the 212A with a 103A modem at 300 bit/s. According to Vadic, the change in frequency assignments made the 212 intentionally incompatible with acoustic coupling, thereby locking out many potential modem manufacturers.
In 1977, Vadic responded with the VA3467 triple modem, an answer-only modem sold to computer center operators that supported Vadic's 1,200-bit/s mode, AT&T's 212A mode, and 103A operation.
Directly connected modems
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The Hush-a-Phone decision applied only to mechanical connections, but the Carterfone decision of 1968 permitted customers to attach devices directly to a telephone line, as long as they followed stringent Bell-defined standards for non-interference with the phone network. This opened the door to direct-connect modems that plugged directly into the phone line rather than via a coupler. However, the cost of passing the tests was considerable, and acoustically coupled modems remained common into the early 1980s.
The rapidly falling prices of electronics in the late 1970s led to an increasing number of direct-connect models around 1980. In spite of being directly connected, these modems were generally operated like their earlier acoustic versions – dialing and other phone-control operations were completed by hand, using an attached handset. A small number of modems added the ability to automatically answer incoming calls, or automatically place an outgoing call to a single number, but even these limited features were relatively rare or limited to special models in a lineup.
When more flexible solutions were needed, third party "dialers" were used to automate calling, normally using a separate serial port to communicate with the dialer, which would then control the modem through a private electrical connection.
The introduction of microcomputer systems with internal expansion slots made the first software-controllable modems common. Slot connections gave the computer complete access to the modem's memory or input/output (I/O) channels, which allowed software to send commands to the modem, not just data. This led to a series of popular modems for the S-100 bus and Apple II computers that could directly dial the phone, answer incoming calls, and hang up the phone, the basic requirements of a bulletin board system (BBS). The seminal CBBS for instance was created on an S-100 machine with a Hayes internal modem, and a number of similar systems followed.
The Hayes Smartmodem
The next major advance in modems was the Hayes Smartmodem, introduced in 1981. The Smartmodem was an otherwise standard 103A 300 bit/s direct-connect modem, but it included a microcontroller that watched the data stream for certain character strings representing commands, which it used to control functions like dialing and answering.
The Hayes command set used by this device became a de-facto standard supported by devices from many other manufacturers. It included instructions for picking up and hanging up the line, dialing and answering calls, among others. This was similar to the commands offered by internal modems, but unlike those, the Smartmodem could be connected to any computer with an RS-232 port, which was practically every microcomputer built.
The introduction of the Smartmodem made communications much simpler and more easily accessed. This provided a growing market for other vendors, who licensed the Hayes patents and competed on price or by adding features.
Through the 1980s, a number of new higher-speed modems, first 1,200 and then 2,400 bit/s, greatly improved the responsiveness of online systems, and made file transfer practical. This led to rapid growth of online services with their large file libraries, which in turn gave more reason to own a modem. The rapid update of modems led to a similar rapid increase in BBS use, which was helped by the fact that BBSs could control the modem simply by sending strings, rather than talking to a device driver that was different for every direct-connect modem.
Increasing speed - 1200 and 2400 bit/s
Higher speed modems began to reach the market eventually, at speeds of 1,200 and 2,400 bit/s. These used new signaling techniques.
Earlier modems used audio frequency-shift keying to send data. In this system, the stream of 1s and 0s in computer data is translated into sounds which can be easily sent on the phone lines.
For instance, in the Bell 103 system, the originating modem sends 0s by playing a 1,070 Hz tone, and 1s at 1,270 Hz, with the answering modem transmitting its 0s on 2,025 Hz and 1s on 2,225 Hz. These frequencies were chosen carefully; they are in the range that suffers minimum distortion on the phone system and are not harmonics of each other.
In the 1,200 bit/s and faster systems, phase-shift keying was used. In this system the two tones for any one side of the connection are sent at similar frequencies as in the 300 bit/s systems, but slightly out of phase.
Voiceband modems generally remained at 300 and 1,200 bit/s (V.21 and V.22) into the mid-1980s. A V.22bis 2,400-bit/s system similar in concept to the 1,200-bit/s Bell 212 signaling was introduced in the U.S., and a slightly different one in Europe. The limited available frequency range meant the symbol rate of 1,200 bit/s modems was still only 600 baud (symbols per second). The bit rate increases were achieved by defining four or eight distinct symbols, which allowed the encoding of two or three bits per symbol instead of only 1.
The use of smaller shifts had the drawback of making each symbol more vulnerable to interference, but improvements in phone line quality at around the same time helped compensate for this. By the late 1980s, most modems could support all of these standards and 2,400-bit/s operation was becoming common.
Many other standards were also introduced for special purposes, commonly using a high-speed channel for receiving, and a lower-speed channel for sending. One typical example was used in the French Minitel system, in which the user's terminals spent the majority of their time receiving information. The modem in the Minitel terminal thus operated at 1,200 bit/s for reception, and 75 bit/s for sending commands back to the servers.
Three U.S. companies became famous for high-speed versions of the same concept. Telebit introduced its Trailblazer modem in 1984, which used a large number of 36 bit/s channels to send data one-way at rates up to 18,432 bit/s. A single additional channel in the reverse direction allowed the two modems to communicate how much data was waiting at either end of the link, and the modems could change direction on the fly. The Trailblazer modems also supported a feature that allowed them to spoof the UUCP g protocol, commonly used on Unix systems to send e-mail, and thereby speed UUCP up by a tremendous amount. Trailblazers thus became extremely common on Unix systems, and maintained their dominance in this market well into the 1990s.
USRobotics (USR) introduced a similar system, known as HST, although this supplied only 9,600 bit/s (in the early versions) and provided for a larger backchannel. Rather than offer spoofing, USR instead created a large market among FidoNet users by offering its modems to BBS sysops at a much lower price, resulting in sales to end users who wanted faster file transfers. Hayes was forced to compete, and introduced its own 9,600 bit/s standard, Express 96 (also known as Ping-Pong), which was generally similar to Telebit's PEP. Hayes, however, offered neither protocol spoofing nor sysop discounts, and its high-speed modems remained rare.
A common feature of these high-speed modems was the concept of fallback, or speed hunting, allowing them to communicate with less-capable modems. During the call initiation, the modem would transmit a series of signals and wait for the remote modem to respond. They would start with standards supporting high speeds and progressively fall back to slower standards until there was a response. Thus, two USR modems would be able to connect at 9,600 bit/s, but, when a user with a 2,400 bit/s modem called in, the USR would fall back to the common 2,400 bit/s speed. This would also happen if a V.32 modem and a HST modem were connected. Because they used a different standard at 9,600 bit/s, they would fall back to their highest commonly supported standard at 2,400 bit/s. The same applies to V.32bis and 14,400 bit/s HST modem, which would still be able to communicate with each other at 2,400 bit/s.
Echo cancellation - 9,600 bit/s
Echo cancellation was the next major advance in modem design.
Local telephone lines use the same wires to send and receive data, which results in a small amount of the outgoing signal being reflected back. This is useful for people talking on the phone, as it provides a signal to the speaker that their voice is making it through the system. However, this reflected signal causes problems for a modem, which is unable to distinguish between a signal from the remote modem and the echo of its own signal.
For this reason, earlier modems split the signal frequencies, so that the devices on either end used different tones, allowing each one to ignore any signals in the frequency range it was using for transmission. Even with improvements to the phone system allowing higher speeds, this splitting of available phone signal bandwidth still imposed limits on modems.
Echo cancellation eliminated this problem. During the call setup and negotiation period, both modems send a series of unique tones and then listen for them to return through the phone system. They measure the total delay time and then set up a local delay loop to the same time. Once the connection is completed, they send their signals into the phone lines as normal, but also into a delay line. When their signal is reflected back, it is mixed with the inverted signal from the delay line, which cancels out the echo. This allowed both modems to use the full spectrum available, doubling the possible speed.
Additional improvements were introduced via the quadrature amplitude modulation (QAM) encoding system. Previous systems using phase shift keying (PSK) encoded two bits (or sometimes three) per symbol by slightly delaying or advancing the signal's phase relative to a set carrier tone. QAM used a combination of phase shift and amplitude to encode four bits per symbol.
Transmitting at 1,200 baud produced the 4,800 bit/s V.27ter standard, and at 2,400 baud the 9,600 bit/s V.32. The carrier frequency was 1,650 Hz in both systems. For many years, most engineers considered this rate to be the limit of data communications over telephone networks.
The introduction of these higher-speed systems also led to the development of the digital fax machine during the 1980s. While early fax technology also used modulated signals on a phone line, digital fax used the now-standard digital encoding used by computer modems. This eventually allowed computers to send and receive fax images.
Breaking the 9,600 bit/s barrier
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The first 9,600 bit/s modem was developed in 1968, and sold for more than $20,000, but had high error rates.
In 1980, Gottfried Ungerboeck from IBM Zurich Research Laboratory applied channel coding techniques to search for new ways to increase the speed of modems. His results were astonishing but only conveyed to a few colleagues. In 1982, he agreed to publish what is now a landmark paper in the theory of information coding. By applying parity check coding to the bits in each symbol, and mapping the encoded bits into a two-dimensional diamond pattern, Ungerboeck showed that it was possible to increase the speed by a factor of two with the same error rate. The new technique was called mapping by set partitions, now known as trellis modulation.
Error correcting codes, which encode code words (sets of bits) in such a way that they are far from each other, so that in case of error they are still closest to the original word (and not confused with another) can be thought of as analogous to sphere packing or packing pennies on a surface: the further two bit sequences are from one another, the easier it is to correct minor errors.
Dave Forney introduced the trellis diagram in a landmark 1973 paper that popularized the Viterbi algorithm. Practically all modems operating faster than 9600 bit/s decode trellis-modulated data using the Viterbi algorithm.
V.32 modems operating at 9600 bit/s were expensive and were only starting to enter the market in the early 1990s when V.32bis was standardized. Rockwell International's chip division developed a new driver chip set incorporating the standard and aggressively priced it. Supra, Inc. arranged a short-term exclusivity arrangement with Rockwell, and developed the SupraFAXModem 14400 based on it. Introduced in January 1992 at $399 (or less), it was half the price of the slower V.32 modems already on the market. This led to a price war, and by the end of the year V.32 was dead, never having been really established, and V.32bis modems were widely available for $250.
V.32bis was so successful that the older high-speed standards had little to recommend them. USR fought back with a 16,800 bit/s version of HST, while AT&T introduced a one-off 19,200 bit/s method they referred to as V.32ter, but neither non-standard modem sold well.
V.42, V.42bis and V.44 standards allow the modem to transmit data faster than its basic rate would imply. For instance, a 53.3 kbit/s connection with V.44 can transmit up to 53.3 × 6 = 320 kbit/s using pure text. However, the compression ratio varies based on the transmitted data, for instance the transfer of already-compressed files (ZIP files, JPEG images, MP3 audio, MPEG video) leads to negligible on-line compression. When using an on-line compression standard, the data rate varies during operation, compressed files might be sent at approximately 50 kbit/s, uncompressed files at 160 kbit/s, and pure text at 320 kbit/s.
In such situations, a small amount of memory in the modem, a buffer, is used to hold the data while it is being compressed and sent across the phone line, but in order to prevent overflow of the buffer, it sometimes becomes necessary to tell the computer to pause the datastream. This is accomplished through hardware flow control using extra lines on the modem–computer connection. The computer is then set to supply the modem at some higher rate, such as 320 kbit/s, and the modem will tell the computer when to start or stop sending data.
V.34/28.8 kbit/s and 33.6 kbit/s
Consumer interest in these proprietary improvements waned during the lengthy introduction of the 28,800 bit/s V.34 standard. While waiting, several companies decided to release hardware and introduced modems they referred to as V.FAST.
In order to guarantee compatibility with V.34 modems once the standard was ratified (1994), manufacturers used more flexible components, generally a DSP and microcontroller, as opposed to purpose-designed ASIC modem chips. This would allow later firmware updates to conform with the standards once ratified.
The ITU standard V.34 represents the culmination of these joint efforts. It employs the most powerful coding techniques available at the time, including channel encoding and shape encoding. From the mere four bits per symbol (9.6 kbit/s), the new standards used the functional equivalent of 6 to 10 bits per symbol, plus increasing baud rates from 2,400 to 3,429, to create 14.4, 28.8, and 33.6 kbit/s modems. This rate is near the theoretical Shannon limit.
When calculated, the Shannon capacity of a narrowband line is , with the (linear) signal-to-noise ratio. Narrowband phone lines have a bandwidth of 3,000 Hz so using (SNR = 30 dB), the capacity is approximately 30 kbit/s.
While 56,000 bit/s speeds had been available for leased-line modems for some time, they did not become available for dial modems until the 90s.
In the late 1990s, technologies to achieve speeds above 33.6kbit/s began to be introduced, colloquially referred to as 56k. Several approaches were used, but all of them began as solutions to a single fundamental problem with phone lines.
By the time technology companies began to investigate speeds above 33.6kbit/s, telephone companies had switched almost entirely to all-digital networks. As soon as a phone line reached a local central office, a line card converted the analog signal from the subscriber to a digital one, and vice versa. While digitally encoded telephone lines notionally provide the same bandwidth as the analog systems they replaced, the digitization itself placed constraints on the types of waveforms that could be reliably encoded.
The first problem was that the process of analog-to-digital conversion is intrinsically lossy, but second, and more importantly, the digital signals used by the telcos were not "linear" - they did not encode all frequencies the same way, instead utilizing a nonlinear encoding (μ-law and a-law) meant to favor the nonlinear response of the human ear to voice signals. This made it very difficult to find a 56kbit/s encoding that could survive the digitizing process.
Modem manufacturers discovered that, while the analog to digital conversion could not preserve higher speeds, digital to analog conversions could. Because it was possible for an ISP to obtain a direct digital connection to a telco, a digital modem - one that connects directly to a digital telephone network interface, such as T1 or PRI - could send a signal that utilized every bit of bandwidth available in the system. While that signal still had to be converted back to analog at the subscriber end, that conversion would not distort the signal in the same way that the opposite direction did.
For this same reason, while 56k did permit 56kbit/s downstream (from ISP to subscriber), the same speed was never achieved in the upstream (from the subscriber to the ISP) direction, because that required going through an analog-to-digital conversion. This problem was never overcome.
Early 56k dial-up products
The first 56k dial-up option was a proprietary design from USRobotics, which they called "X2," because 56k was twice the speed (x2) of 28k modems.
At that time, USRobotics held a 40-percent share of the retail modem market, while Rockwell International held an 80-percent share of the modem chipset market. Concerned with being shut out, Rockwell began work on a rival 56k technology. They joined with Lucent and Motorola to develop what they called "K56Flex" or just "Flex."
Both technologies reached the market around February 1997; although problems with K56Flex modems were noted in product reviews through July, within six months the two technologies worked equally well, with variations dependent largely on local connection characteristics.
The retail price of these early 56K modems was about US$200, compared to $100 for standard 33k modems. Compatible equipment was also required at the Internet service providers (ISPs) end, with costs varying depending on whether their current equipment could be upgraded. About half of all ISPs offered 56k support by October 1997. Consumer sales were relatively low, which USRobotics and Rockwell attributed to conflicting standards.
Standardized 56k (V.90/V.92)
In February 1998, The International Telecommunication Union (ITU) announced the draft of a new 56 kbit/s standard, V.90, with strong industry support. Incompatible with either existing standard, it was an amalgam of both, but was designed to allow both types of modem to by a firmware upgrade. The V.90 standard was approved in September 1998, and widely adopted by ISPs and consumers.
The high upload speed was a tradeoff. 48 kbit/s upstream rate would reduce the downstream as low as 40 kbit/s due to echo effects on the line. To avoid this problem, V.92 modems offer the option to turn off the digital upstream and instead use a plain 33.6 kbit/s analog connection in order to maintain a high digital downstream of 50 kbit/s or higher.
V.92 also added two other features. The first is the ability for users who have call waiting to put their dial-up Internet connection on hold for extended periods of time while they answer a call. The second feature is the ability to quickly connect to one's ISP, achieved by remembering the analog and digital characteristics of the telephone line, and using this saved information when reconnecting.
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As telephone-based 56k modems began losing popularity, some Internet service providers such as Netzero/Juno, Netscape, and others started using pre-compression to increase the throughput and maintain their customer base. The server-side compression operates much more efficiently than the on-the-fly compression done by modems because these compression techniques are application-specific (JPEG, text, EXE, etc.). Website text, images, and Flash media are typically compacted to approximately 4%, 12%, and 30%, respectively. The drawback of this approach is a loss in quality, which causes image content to become pixelated and smeared. ISPs employing this approach often advertise it as "accelerated dial-up".
Controller-based modems vs. Softmodems/Winmodems
Traditionally, modems contain all the electronics and intelligence to convert data from bytes to an analog signal and back again, and to handle the dialing process. These are sometimes referred to as "Controller-based modems." Virtually any modem with a serial connection is controller-based; since the only thing it can receive from the host computer is the bytes of the data stream, it has to handle everything else.
A softmodem is a stripped-down variant that replaces tasks traditionally handled in hardware with software. These can be thought of as little more than a PC sound card with a telephone line-compatible interface. The audio sent and received on the line is generated and processed by software in a device driver running in the PC's operating system. There is little functional difference from the user's perspective, but this design reduces the cost of a modem by moving most of the processing into inexpensive software instead of expensive hardware DSPs and microcontrollers.
Softmodems do not use an RS-232 interface to the host PC because they need to be able to exchange audio data with the PC directly. Instead, they connect over internal buses such as ISA, PCI or PCI Express, or external buses such as USB.
Since the interface is not RS-232, there is no standard for communication with the device directly. Instead, softmodems come with drivers which create a virtual RS-232 port which standard modem software (such as an operating system dialer application) can communicate with, but these drivers are frequently designed only for Windows, with Mac and Linux supported less commonly. The only way to make softmodems work on these platforms is to reverse-engineer their drivers. This has led to these devices sometimes being called Winmodems, to highlight their Windows-only functionality.
Evolution of dial-up speeds
These values are maximum values, and actual values may be slower under certain conditions (for example, noisy phone lines). For a complete list see the companion article list of device bandwidths. A baud is one symbol per second; each symbol may encode one or more data bits.
|Connection||Modulation||Bitrate [kbit/s]||Year released|
|110 baud Bell 101 modem||FSK||0.1||1958|
|300 baud (Bell 103 or V.21)||FSK||0.3||1962|
|1200 modem (1200 baud) (Bell 202)||FSK||1.2||1976|
|1200 modem (600 baud) (Bell 212A or V.22)||QPSK||1.2||1980|
|2400 modem (600 baud) (V.22bis)||QAM||2.4||1984|
|2400 modem (1200 baud) (V.26bis)||PSK||2.4|
|4800 modem (1600 baud) (V.27ter)||PSK||4.8|||
|9600 modem (2400 baud) (V.32)||QAM||9.6||1984|
|14.4k modem (2400 baud) (V.32bis)||trellis||14.4||1991|
|19.2k modem (2400 baud) (V.32 "terbo")||trellis||19.2||1993|
|28.8k modem (3200 baud) (V.34)||trellis||28.8||1994|
|33.6k modem (3429 baud) (V.34)||trellis||33.6||1996|
|56k modem (8000/3429 baud) (V.90)||digital||56.0/33.6||1998|
|56k modem (8000/8000 baud) (V.92)||digital||56.0/48.0||2000|
|Bonding modem (two 56k modems) (V.92)||112.0/96.0|
|Hardware compression (variable) (V.90/V.42bis)||56.0–220.0|
|Hardware compression (variable) (V.92/V.44)||56.0–320.0|
|Server-side web compression (variable) (Netscape ISP)||100.0–1,000.0|
A 1994 Software Publishers Association found that although 60% of computers in US households had a modem, only 7% of households went online. A CEA study in 2006 found that dial-up Internet access was declining in the U.S. In 2000, dial-up Internet connections accounted for 74% of all U.S. residential Internet connections. The United States demographic pattern for dial-up modem users per capita has been more or less mirrored in Canada and Australia for the past 20 years.
Dial-up modem use in the U.S. had dropped to 60% by 2003, and in 2006, stood at 36%. Voiceband modems were once the most popular means of Internet access in the U.S., but with the advent of new ways of accessing the Internet, the traditional 56K modem was losing popularity. The dial-up modem is still widely used by customers in rural areas, where DSL, cable, satellite, or fiber optic service is not available, or they are unwilling to pay what these companies charge. In its 2012 annual report, AOL showed it still collected around US$700 million in fees from dial-up users: about three million people.
"Voice" and "fax" are terms added to describe any dial modem that is capable of recording/playing audio or transmitting/receiving faxes. Some modems are capable of all three functions.
Voice modems are used for computer telephony integration applications as simple as placing/receiving calls directly through a computer with a headset, and as complex as fully automated robocalling systems.
Fax modems can be used for computer-based faxing, in which faxes are sent and received without inbound or outbound faxes ever needing to ever be printed on paper. This differs from efax, in which faxing occurs over the internet, in some cases involving no phone lines whatsoever.
A leased line modem also uses ordinary phone wiring, like dial-up and DSL, but does not use the same network topology. While dial-up uses a normal phone line and connects through the telephone switching system, and DSL uses a normal phone line but connects to equipment at the telco central office, leased lines do not terminate at the telco.
Leased lines are pairs of telephone wire that have been connected together at one or more telco central offices so that they form a continuous circuit between two subscriber locations, such as a business' headquarters and a satellite office. They provide no power or dialtone - they are simply a pair of wires connected at two distant locations.
A dialup modem will not function across this type of line, because it does not provide the power, dialtone and switching that those modems require. However, a modem with leased-line capability can operate over such a line, and in fact can have greater performance because the line is not passing through the telco switching equipment, the signal is not filtered, and therefore higher analog bandwidth is available.
Leased-line modems can operate in 2-wire or 4-wire mode. The former uses a single pair of wires and can only transmit in one direction at a time, while the latter uses two pairs of wires and can transmit in both directions simultaneously. When two pairs are available, bandwidth can be as high as 1.5mbps, a full data T1 circuit.
The term broadband gained widespread adoption in the late 90s to describe internet access technology exceeding the 56 kilobit/s maximum of dialup. There are many broadband technologies, such as various DSL (Digital Subscriber Line) technologies and cable broadband.
DSL technologies such as ADSL, HDSL and VDSL use telephone lines (wires that were installed by a telephone company and originally intended for use by a telephone subscriber) but do not utilize most of the rest of the telephone system. Their signals are not sent through ordinary phone exchanges, but are instead received by special equipment (a DSLAM) at the telephone company central office.
Because the signal does not pass through the telephone exchange, no "dialing" is required, and the bandwidth constraints of an ordinary voice call are not imposed. This allows much higher frequencies, and therefore much faster speeds. ADSL in particular is designed to permit voice calls and data usage over the same line simultaneously.
Similarly, cable modems use infrastructure originally intended to carry television signals, and like DSL, typically permit receiving television signals at the same time as broadband internet service.
Different terms are used for broadband modems, because they are frequently contain more than just a modulation/demodulation component.
Because high speed connections are frequently used by multiple computers at once, many broadband modems do not have direct (e.g. USB) PC connections, but connect over a network such as Ethernet or Wi-Fi. Early broadband modems offered Ethernet handoff allowing the use of one or more public IP addresses, but no other services such as NAT and DHCP that would allow multiple computers to share one connection. This led to many consumers purchasing separate "broadband routers," placed between the modem and their network, to perform these functions.
Eventually, ISPs began providing residential gateways which combined the modem and broadband router into a single package that provided routing, NAT, security features, and even Wi-Fi access in addition to modem functionality, so that subscribers could connect their entire household without purchasing any extra equipment. Even later, these devices were extended to provide "triple play" features such as telephony and television service. Nonetheless, these devices are still often referred to simply as "modems" by service providers and manufacturers.
Consequently the terms "modem," "router" and "gateway" are now used interchangeably in casual speech, but in a technical context "modem" may carry a specific connotation of basic functionality with no routing or other features, while the other terms describe a device with features such as NAT.
Broadband modems may also handle authentication such as PPPoE. While it is often possible to authenticate a broadband connection from a users PC, as was the case with dial-up internet service, moving this task to the broadband modem allows it to establish and maintain the connection itself, which makes sharing access between PCs easier since each one does not have to authenticate separately. Broadband modems typically remain authenticated to the ISP as long as they are powered on.
Modern telecommunications and data networks also make extensive use of radio modems where long distance data links are required. Such systems are an important part of the PSTN, and are also in common use for high-speed computer network links to outlying areas where fiber optic is not economical.
Wireless modems come in a variety of types, bandwidths, and speeds. Wireless modems are often referred to as transparent or smart. They transmit information that is modulated onto a carrier frequency to allow many wireless communication links to work simultaneously on different frequencies.[relevant? ]
Transparent modems operate in a manner similar to their phone line modem cousins. Typically, they were half duplex, meaning that they could not send and receive data at the same time. Typically, transparent modems are polled in a round robin manner to collect small amounts of data from scattered locations that do not have easy access to wired infrastructure. Transparent modems are most commonly used by utility companies for data collection.
Smart modems come with media access controllers inside, which prevents random data from colliding and resends data that is not correctly received. Smart modems typically require more bandwidth than transparent modems, and typically achieve higher data rates. The IEEE 802.11 standard defines a short range modulation scheme that is used on a large scale throughout the world.
Modems which use a mobile telephone system (GPRS, UMTS, HSPA, EVDO, WiMax, etc.), are known as mobile broadband modems (sometimes also called wireless modems). Wireless modems can be embedded inside a laptop, mobile phone or other device, or be connected externally. External wireless modems include connect cards, USB modems, and cellular routers.
Most GSM wireless modems come with an integrated SIM cardholder (i.e. Huawei E220, Sierra 881.) Some models are also provided with a microSD memory slot and/or jack for additional external antenna, (Huawei E1762, Sierra Compass 885.)
Until the end of April 2011, worldwide shipments of USB modems surpassed embedded 3G and 4G modules by 3:1 because USB modems can be easily discarded. Embedded modems may overtake separate modems as tablet sales grow and the incremental cost of the modems shrinks, so by 2016, the ratio may change to 1:1.
Like mobile phones, mobile broadband modems can be SIM locked to a particular network provider. Unlocking a modem is achieved the same way as unlocking a phone, by using an 'unlock code'.
A modem that connects to a fiber optic network is known as an optical network terminal (ONT) or optical network unit (ONU). These are commonly used in fiber to the home installations, installed inside or outside a house to convert the optical medium to a copper Ethernet interface, after which a router or gateway is often installed to perform authentication, routing, NAT, and other typical consumer internet functions, in addition to "triple play" features such as telephony and television service.
Fiber optic systems can use quadrature amplitude modulation to maximize throughput. 16QAM uses a 16-point constellation to send four bits per symbol, with speeds on the order of 200 or 400 gigabits per second. 64QAM uses a 64-point constellation to send six bits per symbol, with speeds up to 65 terabits per second. Although this technology has been announced, it may not yet be commonly used.
Although the name modem is seldom used, some high-speed home networking applications do use modems, such as powerline ethernet. The G.hn standard for instance, developed by ITU-T, provides a high-speed (up to 1 Gbit/s) local area network using existing home wiring (power lines, phone lines and coaxial cables). G.hn devices use orthogonal frequency-division multiplexing (OFDM) to modulate a digital signal for transmission over the wire.
As described above, technologies like Wi-Fi and Bluetooth also use modems to communicate over radio at short distances.
The phrase "null modem" was common parlance in the heydey of RS-232 communication between computers, but as the name suggests, it in fact describes the absence of a modem.
A null modem cable is a specially wired cable connected between the serial ports of two personal computers, with the transmit and receive lines reversed. The name referred to the use of this type of cable to connect two computers for applications where a modem would typically be used, and the same software used with modems (such as Procomm or Minicom) could be used with this type of connection.
A "short haul modem" is a device that bridges the gap between leased-line and dial-up modems. Like a leased-line modem, they transmit over "bare" lines with no power or telco switching equipment, but are not intended for the same distances that leased lines can achieve. Ranges up to several miles are possible, but significantly, short-haul modems can be used for medium distances, greater than the maximum length of a basic serial cable but still relatively short, such as within a single building or campus. This allows a serial connection to be extended for perhaps only several hundred to several thousand feet, a case where obtaining an entire telephone or leased line would be overkill.
While some short-haul modems do in fact use modulation, low-end devices (for reasons of cost or power consumption) are simple "line drivers" that increase the level of the digital signal but do not modulate it. These are not technically modems, but the same terminology is used for them.
- Manjoo, Farhad (2009-02-24). "The unrecognizable Internet of 1996". Slate Magazine. Retrieved 2020-08-10.
- Brenner, Joanna. "3% of Americans use dial-up at home". Pew Research Center. Retrieved 2020-08-10.
- inventors, Mary Bellis Mary Bellis wrote on the topics of; Years, Inventions for 18; Producer, Was a Film; director. "Where Did the Modem Come From?". ThoughtCo. Retrieved 2018-12-12.
- "Modem entry". Archived from the original on 2014-07-11.
- Powers, E.; Zimmermann, M. (1968). TADIM—A Digital Implementation of a Multichannel Data Modem. International Conference on Communications. IEEE. p. 706.
With the advent of digital microelectronic integrated circuits and MOS FET shift register memories the application of "wholesale" technology to the implementation of a digital multichannel modem became extremely attractive for providing the advantages of extremely small size, light weight, high reliability and low cost, in addition to the inherent stability and freedom from adjustment provided by digital circuitry.
- Internet, Tamsin Oxford 2009-12-26T11:00:00 359Z. "Getting connected: a history of modems". TechRadar. Retrieved 2018-12-12.
- Mark Anderson. "David Forney: The Man Who Launched a Million Modems". 2016.
- IEEE History Center. "Gottfried Ungerboeck Oral History". Archived from the original on June 25, 2007. Retrieved 2008-02-10.
- Ungerboeck, Gottfried (1982). "Channel coding with multilevel/phase signals". IEEE Trans. Inf. Theory. IT-28: 55–67.
- "Modem compression: V.44 against V.42bis". Pricenfees.com. Archived from the original on 2017-02-02. Retrieved 2014-02-10.
- "Re: Modems FAQ". Archived from the original on January 4, 2007. Retrieved 2008-02-18. - Wolfgang Henke.
- Held, Gilbert (2000). Understanding Data Communications: From Fundamentals to Networking Third Edition. New York: John Wiley & Sons Ltd. pp. 68–69.
- "x2 White Paper". web.archive.org. 1997-06-07. Retrieved 2020-06-29.
- Ross, John A. (John Allan), 1955- (2001). Telecommunication technologies : voice, data & fiber-optic applications. Indianapolis, Ind.: Prompt. p. 185. ISBN 0-7906-1225-9. OCLC 45745196. Archived from the original on 2019-10-19.CS1 maint: multiple names: authors list (link)
- Greenstein, Shane; Stango, Victor (2006). Standards and Public Policy. Cambridge University Press. pp. 129–132. ISBN 978-1-139-46075-0. Archived from the original on 2017-03-24.
- "Agreement reached on 56K Modem standard". International Telecommunication Union. 9 February 1998. Archived from the original on 2 October 2017. Retrieved 5 September 2018.
- "V.92: Enhancements to Recommendation V.90". www.itu.int. Retrieved 2020-06-29.
- "V.92 - News & Updates". November and October 2000 updates. Archived from the original on 20 September 2012. Retrieved 17 September 2012.
- "USRobotics 56K Modem Education: What are the different types of modems?". support.usr.com. Retrieved 2020-08-11.
- tsbmail (2011-04-15). "Data communication over the telephone network". Itu.int. Archived from the original on 2014-01-27. Retrieved 2014-02-10.
- "29.2 Historical Modem Protocols". tldp.org. Archived from the original on 2014-01-02. Retrieved 2014-02-10.
- "concordia.ca — Data Communication and Computer Networks" (PDF). Archived from the original (PDF) on 2006-10-07. Retrieved 2014-02-10.
- "Group 3 Facsimile Communication". garretwilson.com. 2013-09-20. Archived from the original on 2014-02-03. Retrieved 2014-02-10.
- "upatras.gr - Implementation of a V.34 modem on a Digital Signal Processor" (PDF). Archived from the original (PDF) on 2007-03-06. Retrieved 2014-02-10.
- Jones, Les. "Bonding: 112K, 168K, and beyond". 56K.COM. Archived from the original on 1997-12-10.
- "Software Publishing Association Unveils New Data". Read.Me. Computer Gaming World. May 1994. p. 12. Archived from the original on 2014-07-03.
- Suzanne Choney. "AOL still has 3.5 million dial-up subscribers - Technology on NBCNews.com". Archived from the original on 2013-01-01. Retrieved 2014-02-10.
- ID, FCC. "E110 56K DATA / FAX VOICE SPEAKPHONE EXTERNAL MODEM User Manual PTT Turbocomm Tech ". FCC ID. Retrieved 2020-08-13.
- "MODEMS lease line modem". www.data-connect.com. Retrieved 2020-08-11.
- "HUAWEI E1762,HSPA/UMTS 900/2100 Support 2Mbps (5.76Mbps ready) HSUPA and 7.2Mbps HSDPA services". 3gmodem.com.hk. Archived from the original on 2013-05-10. Retrieved 2013-04-22.
- "Sierra Wireless Compass 885 HSUPA 3G modem". The Register. Archived from the original on 2013-01-04. Retrieved 2014-02-10.
- Lawson, Stephen (May 2, 2011). "Laptop Users Still Prefer USB Modems". PCWorld. IDG Consumer & SMB. Archived from the original on September 27, 2016. Retrieved 2016-08-13.
- Michael Kassner (February 10, 2015). "Researchers double throughput of long-distance fiber optics". TechRepublic. Archived from the original on November 9, 2016.
- Bengt-Erik Olsson; Anders Djupsjöbacka; Jonas Mårtensson; Arne Alping (6 Dec 2011). "112 Gbit/s RF-assisted dual carrier DP-16-QAM transmitter using optical phase modulator" (PDF). Optics Express. Optical Society of America. 19 (26): B784-9. Bibcode:2011OExpr..19B.784O. doi:10.1364/oe.19.00b784. PMID 22274103.[permanent dead link]
- Stephen Hardy (March 17, 2016). "ClariPhy targets 400G with new 16-nm DSP silicon". LIGHTWAVE. Archived from the original on November 9, 2016.
- "ClariPhy Shatters Fiber and System Capacity Barriers with Industry's First 16nm Coherent Optical Networking Platform". optics.org. 17 Mar 2016.
- "Nokia Bell Labs achieve 65 Terabit-per-second transmission record for transoceanic cable systems". Noika. 12 October 2016. Archived from the original on 9 November 2016. Retrieved 8 November 2016.
- "Modem". www.trine2.net.au. Retrieved 2020-08-13.
|Wikibooks has a book on the topic of: Transferring Data between Standard Dial-Up Modems|
|Wikimedia Commons has media related to Modems.|
- Hayes-compatible Modems and AT Commands from the Serial Data Communications Programming Wikibook
- International Telecommunications Union ITU: Data communication over the telephone network
- "Columbia University - Protocols Explained". Archived from the original on June 19, 2006. Retrieved August 12, 2007. – no longer available, archived version
- Basic handshakes & modulations – V.22, V.22bis, V.32 and V.34 handshakes
- Getting connected: a history of modems – techradar
- Data/FAX Modem Transmission Modulation Systems – baud rates and modulation schemes


So, I found out yesterday why we're having so many difficulties with network connectivity at TELS. It seems that QWest changed the length of our local loop from 13k feet to 18k feet. Considering that a DSL line is 15k feet at the outside, this was causing a lot of problems. The line has been put into "Safe mode" so that the connectivity speed is down but the line is a lot more reliable.
This relates somewhat the net connection at the new place since it is 16040 ft from the CO. Speakeasy tells me that they'll not be able to give me a DSL line there since it is too far. This doesn't make for a happy Torin. I'm thinking that I'll try contacting QWest again to see if they can get me DSL service. Otherwise, I'll have to use Comcast. Definitely not something that I want to do but it's better than -no- high speed network.


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Voice-enabling smart-home devices with Amazon Alexa (Part III)
May 1, 2017
In the previous installment of our Alexa skills development exploration, we got to the point of building smarthome and custom skills for Amazon…
Voice-enabling smart-home devices with Amazon Alexa (Part II)
April 23, 2017
In the previous post, we discussed setting-up Amazon Alexa skills and an environment for building and deploying an autoscaling service to host processing…
Voice enabling smart-home devices with Amazon Alexa
March 22, 2017
Our client is a smart-home devices manufacturer. The company decided to voice-enable their products, starting with an ability to interact with the Amazon…


About The E-Book
- Title – Beginning Sensor Networks with Arduino and Raspberry Pi
- Author – Charles Bell
- Total Pages – 358 Pages
- Total Chapters – 09 Chapters
- File Size – 13 MBs
Beginning Sensor Networks with Arduino and Raspberry Pi teaches you how to build sensor networks with Arduino, Raspberry Pi, and XBee radio modules, and even shows you how to turn your Raspberry Pi into a My SQL database server to store your sensor data.
First you’ll learn about the different types of sensors and sensor networks, including how to build a simple XBee network. Then you’ll walk through building an Arduino based temperature sensor and data collector, followed by building a Raspberry Pi based sensor node.
Next, you’ll learn different ways to store sensor data you’ll learn how to put it all together by connecting your Arduino sensor node to your new Raspberry Pi database server.
Thank You 🎀
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Zilkr builds platforms that API-enable an enterprise’s telecom network. Requests and events in the telecom network, such as incoming calls, messages or outgoing calls, can now be integrated with Internet-based services.
Zilkr came to Ignite to help conceptualize what such an integrated phone and desktop experience could look like. Furthermore, Zilkr wanted to explore what such an experience would require from a technology protocol perspective to allow 3rd party apps to execute in the Zilkr framework.
Ignite approached this as a high-intensity, design thinking project. We engaged with Zilkr’s senior management to outline user stories for key scenarios such as incoming calls and the tools required for salespersons, supporting outgoing calls and reminders and identifying spam calls.
Rather than jump into this from a UX design perspective, we applied a design thinking approach to balance the business needs of Zilkr, the user’s expectations and intuitive interfaces and the technology protocol that would sustain such a framework for 3rd party developed apps.
We developed a dynamic, interactive prototype that demonstrated all aspects of the user stories.
Zilkr was successful in taking this interactive prototype to their customers and getting traction for a new offering.


Sony Defends its Xperia Pro Price at $2,500 with 5G, OLED Display, 360-Degree Antenna, and More ( Screenshot From MrMobile [Michael Fisher] YouTube )
A number of device makers would regularly throw around the popular word “Pro” to make a phone model more attractive to those buyers looking for premium devices. However, when it comes to the Sony Xperia Pro costing $2,500, it is said that the company does mean what it says.
How much is Sony Xperia Pro?
According to an article by Gizmodo, although the Xperia Pro still shares a lot of the same gut design as the previous Xperia 1 ii, Sony still added a number of improvements to help photographers, videographers, and even broadcasting professionals.
- Micro HDMI port – this reportedly allows users to connect their Xperia Pro into a nearby camera.
- 5G modem – when the phone is connected to a camera, the Xperia Pro can then take footage from the much bigger camera and immediately upload it towards a broadcast station or users can also live stream their content directory across a number of platforms.
- USB-C – for content that is less time sensitive, users have the option of transferring the pics or the videos towards the Xperia Pro through a USB-C which will be automatically uploaded through the use of a specified FTP
- External Monitor app – this allows the phone to connect to a Sony Alpha camera in order to use it as visuals
- OLED display – the phone has a 6.5 inch OLED display which has a lot of adjustable options on the phone.
- Triple cam module – this can be used to capture both photos and videos
Aside from these interesting functions, the Sony Xperia Pro has a few powerful features as well.
- Micro HDMI port
- IP 68 water resistance
- Gorilla Glass 6 Screen
- 360-degree antenna design – allow radio waves to connect faster
- Network Visualizer – allows user to see connection signal more thoroughly
Despite the positive upgrades, there are also reportedly a few turnoffs for this new phone as reported by the article namely the use of older Qualcomm Snapdragon 865 chips and the X55 modem and the battery life of just 4,000 mAh.
Is the Sony Xperia Pro worth the price?
On the GSMArena page, the Xperia Pro had mostly positive reviews while others were trying to defend its price by saying that it is a niche product and not for everyone as Sony clearly said. An Anonymous comment, however, noted that the phone would get cheaper in time.
The specs on DroidChart gave this particular smartphone a rating of 4 out of 5 stars. While the phone’s specs are much appreciated, there is still speculation online as to whether the phone being priced at $2,500 is justifiable with the given features. The said features, although quite beneficial, are still being bought at a hefty price of $2,500 and to top everything off, the Sony Xperia Pro uses the Snapdragon 865 chips instead of the newer Snapdragon 888 chips by Qualcomm.


Volume Control Attenuator
23 steps auto wound transformer of volume control
It has 23 steps for 50 dB of attenuation .It could improve the quality of sound better. It also feels warm, smoothly ,and clear in the performance of sound.
It is a loss-less volume attenuator for high end audio system.The main function of TC-6 is to adjust voltage level from the output of signal.
Like a CD player or other equipment which has RCA terminal for outputting signal.The advantage is that TC-6 has less power dissipation on attenuator
because we use transformers to replace traditional volume control (Variable Resistors type).
The drawback of VR type has higher power losses on resistors. So the power of signal will be absorbed by resistors. The quality of VR type is limited by
the resistors. VR type of volume controller will influence to the sound quality for signal.
Because TC-6 uses windings and turns ration to determine the voltage level of input signal, there will be quite less power dissipation on windings.
Therefore, it is more efficient than VR type.
It be sited between source (AUX-CD-DVD ) and preamplifier.
There are two kinds of type for choice. (A-type and G-type)


Before 1994, the Ministry of Posts and Telecommunications [disambiguation needed] (MTP) if telecom benefits through its operational arm, China Telecom. Influenced by different services and contradicting clients, the Chinese government authoritatively began the telecom business changes in 1994 by presenting another contender: China Unicom. China Unicom could barely contend with the mammoth China Telecom.
In 1998, because of a pastoral redesign, the MTP was supplanted by the new Ministry of Information Industry (MII). The MII took two vast scale reshuffling activities focusing on the wasteful state-imposing business model.
In 1999 the principal rebuilding split China Telecom's business into three sections (settled line, portable and satellite). China Mobile and China Satcom were made to run, individually, the portable and satellite parts yet China Telecom kept on being a syndication of settled line administrations.
The second rebuilding in 2002 split China Telecom Engineering geologically into north and south: China Telecom - North kept 30% of the system assets and shaped China Netcom (CNC) and 70% of the assets were held by China Telecom - South or basically the new China Telecom. Parallel to this twofold splitting, the broadcast communications division of the Ministry of Railways (MOR) built up another on-screen character in 2000: China TieTong.
These assets comprised of a 2,200,000 km long across the country optical system, in view of Asynchronous Transfer Mode (ATM), Synchronous Digital Hierarchy (SDH) and Dense Wavelength Division Multiplexing (DWDM) innovations and a few submarine links, specifically with the USA, Japan, Germany and Russia. To whole up, the Chinese telecom industry has transformed from a state-run monopolistic structure to state-run oligopolistic structure.


Qualcomm Atheros QCA9531 650MHZ CPU
Support connect to 35client+
Complies with IEEE 802.11n/g/b standards for 2.4GHz Wireless LAN.
Up to 300Mbps data rate for Wi-Fi network.
Practical and elegant ceiling mount design.
Advanced MIMO technology enhances the throughput and wireless coverage.
Provides 64/128-bit WEP, WPA, WPA2 and WPA/WPA2 security.
Multiple BSS allows user to add other SSIDs for access management.
AP/Station Mode/Repeater mode selectable for different requirements.
PoE power supply 48V 0,5A supported simplify the deployment.


Fibre Atlantic submarine cable system
The Fibre Atlantic Cable System is a concept developed by SemanticNet BV in order to provide for more security, diversity and cheaper capacity across the Atlantic. Fibre Atlantic focuses on the promotion and development of new subsea cable systems following diverse paths across the Atlantic, e.g. Virginia Beach and Bordeaux, France; a unique cable route not crossing another transatlantic cable system and bypassing major congestion points. For more information about our services or need help with your project, feel free to contact us.
We believe that the Internet has become a fundamental resource as important as air, water, food and shelter. That is why we decided to usher in a new era of transatlantic capacity.Read more


Leading telecommunications company Securus Technologies has recently issued a number of corrections to a press release by competitor GTL on June of 2016. According to sources, Global Tel Link had a press release that contained a number of statements that were found to be false and inaccurate. As a result, Securus Technologies has looked to correct the press release so that it reveals true and correct information. With this effort, Securus Technologies will be in position to help provide clarification and credibility among members in the telecommunications industry.
Over the most recent months, Securus Technologies has made a number of corrections that will help allow consumers to gain a more accurate perspective on recent trends in the telecommunications industry. The company has made a number of corrections to multiple statements made by Global Tel Link. With these corrections, the available information in press releases will now be providing the truth about recent facts about the telecommunications industry.
Securus Technologies has made corrections on a number of recent allegations by Global Tel Link. One of these was one in which GTL stated that a recent decision by the United States Patent Trial and Appeals Board allows GTL to move forward in seeking injunctions for damages by Securus. However, Securus Technologies countered by saying that GTL is now unable to seek any legal action which includes being unable to seek injunctions for damages.
Another allegation made by GTL was that all 55 claims of the 816 patent were preserved. This means that GTL has technology for video visitation monitoring in prisons. According to Securus Technologies, GTL is only asserting one individual claim,
In the third allegation, Global Tel Link said that they are pleased that the innovations they made are patentable. However, Securus made a correction which said that the PTAB did not determine that GTL has any innovations that can be patented.


Looking For Oil | Does It Make CeNSE?
On HP’s new global sensor system (Central Nervous System for the Earth):
“In the first commercial application of CeNSE technology, HP and Shell will build a wireless sensing system to acquire high-resolution seismic data. By vastly improving the quality of seismic imaging, the new system will allow Shell to more easily and cost-effectively explore difficult oil and gas reservoirs.” HP Labs
“The world’s best seller of PCs and its biggest oil company will collaborate on a wireless sensor network to aid in oil exploration. In the system they imagine, sensors like the one seen above will be laid on the ground at regular intervals across hundreds of square miles, listening for sound waves bounced through miles of sub-strata and hopefully pockets of oil.” Fast Company
“The creation of a global sensor system would be an incredible breakthrough – it could make our cities more efficient, save lives, and enable us to better understand, track, and combat climate change. As HP Labs senior researcher Peter Hartwell has stated, “If we’re going to save the planet, we’ve got to monitor it“. Inhabitat
As much as I’d like the latter, it’s hard to tell. Is the point to make smarter, more sustainable cities or to (sustainably??) discover the very last bits of the non-renewable resource?
According to HP, “the solution will provide a better picture of existing and alternative energy resources – allowing Shell to perform more targeted oil exploration and reduce their environmental impact.”


Communicate With the
Intercoms can be the key point of communication between you and the front door of your home or business.
They can protect you and your loved ones. Safe and secure, without having to open the front door. Voice and video make it a safe and easy way of screening all visitors before you let them in.
Intercoms give two-way communication through voice and video intercoms and have the ability to unlock the door of the gate from a base station inside your home or business should you wish to let that person in.
Issues We Can
Help You With
Conversations between rooms in the home or office are as easy as pressing a button.
Systems can be designed to:
- Release the door electronically
- Monitor an infant
- See who’s at the front door/gate
Intercom technology of today also enables you to store images of who has been at the door if you were away.
We specialise in both residential and commercial applications and have a system to suit any need or budget.
Our team is ready to discuss your security requirements, so why not give us a call.
Home Intercom Systems
There are many advantages to investing in a home intercom system.
Benefits of a home intercom system include:
- Voice and video connections provide the ability to identify visitors before allowing them entrance to the property, leading to increased home security
- Can prevent crime by deterring criminals due to the presence of a camera (and providing evidence in the event of a crime)
- May increase the value of your home
Some home intercoms can be paired with your smart device, allowing you to control the system remotely
- Home intercoms may be able to be integrated with your entire home security system or electronic lock system
- Answer the door from anywhere in your home
Need to Upgrade Your Current Home Intercom System?
If you want to update your current home intercom system, we can help design a new setup with the features you want. We partner with you to ensure your home intercom system is functional, convenient, and in line with your desired level of security.
Commercial Intercom Systems
Commercial intercom systems are ideal for a vast range of commercial, industrial, and office applications.
For certain industries, a commercial intercom system can be especially important. Along with the higher level of security offered by these features, an intercom system also allows staff to maintain communication with each other and easily broadcast announcements.
Benefits of commercial intercom systems include:
- Secure, two-way communication between staff members
- Help occupants, visitors, and staff members feel safe and secure
- Staff can easily monitor and control who is allowed to access the property
- Voice and video connections for easy monitoring
- Can offer contactless entry or remote access
- A convenient way to manage foot traffic in commercial properties
If you want to amp up security for your business or property and enable easy communication between staff members, ask us about our custom commercial intercom solutions. We can design and install commercial intercom systems specifically suited to your location, setup, building size, security goals, and communication needs.
Why Choose Us
At Diamond Locksmiths, we’ve been helping home and business owners keep their properties and assets secure for decades.
For a custom intercom Perth homeowners can trust to provide the ultimate convenience and high security, our professional, friendly team at Diamond Locksmiths is ready to deliver. Contact our experts today to learn about our personalised home and commercial intercom systems.
While both kinds of systems work well, their usefulness varies depending on the situation. Wireless intercoms are easy to install and work well in smaller homes and businesses. A wired intercom system is more challenging to install. However, a wired intercom is a smart choice if you are in a large building.
You can get many results by integrating a new intercom with your existing security system. Typically, your installer integrates the intercom into an access control system. This is an ideal way to control who can and cannot enter your property.
Many intercom systems have capabilities that extend beyond speaking with someone in another part of the building. Video calling is one of the most popular features of intercoms. However, depending on the model, your intercom can:
- Offer noise cancellation
- Access the internet
- Group calling
- Remote access
Standard intercoms are not equipped for remote monitoring. However, you can purchase intercoms that have such features. You will also need to connect your intercom to the internet for remote monitoring.
Because of the wide variety of intercom systems on the market, quoting a specific one-size-fits-all price is nearly impossible. However, the price of an intercom is often dictated by the following factors:
- The Cost of the Equipment- A basic system will cost less than a high-tech top of the line intercom.
- How Many Intercom Units are Included- A two-unit intercom will be less expensive than a multi-unit setup.
- Installation Costs- You should hire a professional to install your intercom system. Additionally, a hard-wired system for your building will cost more than a wireless one.
- Maintenance Costs- Some systems come with a monthly monitoring fee. Wireless systems will need an occasional charge to keep the battery running.


Rotork selected for valve automation at the Olivenza Thermosolar power plant
Rotork intelligent electric valve actuation with digital 2-wire monitoring and control has been specified for valve automation at the Olivenza Thermosolar power plant in Spain, a CSP (Concentrated Solar Power) technology facility generating eco-friendly electricity for up to 50,000 households.
More than 100 IQ actuators and two Pakscan P3 hot-standby master stations have been supplied, fully installed, cabled and commissioning by Rotork Iberia. Rotork’s intelligent IQ actuator technology is widely recognised as industry-standard for isolating and regulating valve duties in the field of power generation. The use of solid-state electronics as an alternative to switch mechanisms and counter limiting devices, combined with programmable micro-processor based control and instrumentation functionality, offers many proven benefits.
These include ‘non-intrusive’ configuration and data transfer by means of a hand held instrument via a secure, bi-directional link. This system is used to perform all the switch setting and commissioning functions that were traditionally only achieved by removing electrical covers. Using the multi-lingual menu on the actuator display screen, it is quick and easy to commission the valve, with or without mains power connected.
The same instrument is used to download this data and upload it to other IQ actuators with similar commissioning parameters, simplifying and speeding up the operation, or to download actuator operating information from the actuator’s data logger.
The inclusion of a data logger enables an event-by-event history of valve activity to be generated, including torque profiles produced during each opening and closing. Using Rotork’s IQ-Insight2 software, these can be compared with the valve torque signature profile logged during the commissioning process to identify the trend of valve operating wear or isolate tight spots and other problems. Analysis of this data improves asset management through fault diagnostics and preventative maintenance.
Digital two-wire control is provided by Rotork’s proprietary Pakscan P3 system, the third generation of a market-leading product, capable of monitoring and controlling up to 240 field units without repeaters on a single highway with a length of up to 20 kilometres. Designed specifically for the valve actuation environment, Pakscan combines high reliability and efficiency with low maintenance costs. In providing the vital link between the actuators in the field and the centralised supervisory control room, Pakscan incorporates secure field communications with inbuilt network redundancy to maintain control even in the event of equipment or cable failure.
Rotork Pakscan has been widely adopted in many worldwide industries, where the use of a fully redundant two-wire bus loop linking multiple numbers of actuators over long distances is recognised as delivering reliable monitoring and control with dramatically reduced installation and cabling costs in comparison with traditional hard wiring.
The Olivenza Thermosolar power plant is the second plant to be operated by the Spanish company Ibereolica. Rotork supplied IQ range electric actuators with Pakscan digital control at the company’s first plant, Moron Thermosolar, and the satisfactory experience on this project, where installation and commissioning was performed on time and without incident, has enabled Ibereolica to select the same Rotork equipment again. As with the Moron project, Seridom has been the main contractor for Olivensa Thermosolar.


In today’s digital age, having a fast and reliable internet connection is crucial for both personal and professional use. Whether you work from home, stream your favorite movies and TV shows, or play online games, a strong internet connection is a necessity. However, sometimes the quality of your internet service can be hindered by poor data line installation. That’s where professional data line installation comes into play, offering a transformative experience for your internet connection.
The Importance of Data Line Installation
When it comes to internet connectivity, the quality of data line installation plays a significant role in determining the speed and reliability of your connection. Many households and businesses rely on outdated or poorly installed data lines, resulting in slow internet speeds, frequent disconnections, and latency issues. These problems can be frustrating and can hinder productivity and leisure activities.
Professional data line installation is crucial for a variety of reasons. Firstly, it ensures that the data lines are correctly installed, minimizing signal loss and interference. Professional technicians have the expertise to handle delicate cables and connectors, ensuring optimal performance. Additionally, they can troubleshoot any issues that may arise during the installation process, ensuring a seamless and hassle-free experience for the end-user.
Benefits of Professional Data Line Installation
Investing in professional data line installation can have a myriad of benefits for both residential and commercial users. Let’s explore some of the advantages:
1. Enhanced Internet Speeds
One of the most significant advantages of professional data line installation is the improvement in internet speeds. A well-planned and high-quality installation ensures minimal signal loss, leading to faster and more consistent internet speeds. This is especially important for businesses that rely on a fast and reliable internet connection to serve their customers and complete daily operations efficiently.
2. Improved Reliability
Professional data line installation eliminates connectivity issues and reduces internet downtime. With proper installation techniques, the risk of cable damage and signal loss is significantly minimized, resulting in a more reliable connection. This is particularly beneficial for businesses that heavily rely on uninterrupted internet access, such as e-commerce platforms, remote offices, and online service providers.
3. Reduced Latency
Latency refers to the delay in data transmission from one point to another. Slow data lines can lead to high latency, causing delays when loading web pages, streaming videos, or gaming online. By opting for professional data line installation, you can minimize latency issues, ensuring a smooth and responsive internet experience.
4. Future-Proofing your Network
Technology is constantly evolving, and internet requirements are increasing. Professional data line installation ensures that your network is future-proofed, capable of handling higher bandwidth demands and emerging technologies. This means that you won’t have to upgrade your infrastructure every few years to keep up with changing demands, ultimately saving you time and money in the long run.
5. Minimized Interference
Data lines are susceptible to interference caused by various factors such as electromagnetic interference (EMI) from nearby electrical equipment, poor cable management, or incorrect installation techniques. Professional data line installation takes all necessary precautions to minimize interference, ensuring a stable and interference-free internet connection.
Choosing Professional Data Line Installation Services
When it comes to selecting a professional data line installation service, there are a few key factors to consider:
1. Experience and Expertise
Look for a service provider with extensive experience in the field of data line installation. Experienced technicians will have the necessary skills and knowledge to handle complex installations and troubleshoot any issues that may arise during the process.
2. Quality Materials
Ensure that the service provider uses high-quality data cables, connectors, and other necessary materials for the installation. The use of substandard materials can compromise the integrity of the installation and lead to future issues.
3. Excellent Customer Service
Choose a service provider that values customer satisfaction and offers excellent customer service. A reputable company will be responsive, communicate effectively, and address any concerns or queries you may have throughout the installation process.
4. Competitive Pricing
While cost should not be the sole determining factor, consider the pricing of the services offered. Look for a service provider that offers competitive pricing without compromising on the quality of their work.
In conclusion, investing in professional data line installation can significantly transform your internet experience. By enhancing internet speeds, improving reliability, reducing latency, future-proofing your network, and minimizing interference, professional data line installation ensures a seamless and efficient internet connection. When selecting a service provider, prioritize experience, expertise, quality materials, and excellent customer service. So, why settle for an average internet connection when you can take advantage of professional data line installation and enjoy an exceptional online experience?


Apple announced the thinnest (7.6 mm) and lightest (112 grams) iphone 5 operates on iOS 6. Features 4 inches touch display, A6 chip, 4G LTE network support, upgraded Wi-Fi, panoramic 8-megapixel camera, improved speakers, greater battery life and a new dock and connector. Pricing starts at $199 for 16 GB, 32 GB for $299 and $399 for 64 GB respectively with 2 years contract. Pre-order starts from September14th. Shipping starts Sept. 21 in US, Canada, and several other countries.
iPhone 5 Features :
- Fast 4G LTE data connection
- 20 percent lighter than 4S (112 grams)
- 18 percent thinner (7.6 mm)
- Available on Verizon/Sprint/ATT
- 4-inch display 1136x640 pixel resolution
- Processor and graphics are 2x faster (new A6 chip)
- Battery: 8 hours talk time, 225 hours standby.
- Camera: 8 megapixel, 3264x2448 resolution, f/2.4 aperture, panorama feature, 1080p HD video, front-facing Facetime camera updated (720p) and face detection, improved mics and speakers.
- New smaller connector called Lightning. 8 pin, reversible (adaptor available for current connector).


The Marketo REST API supports HTTP compression of response bodies using standards defined by the HTTP 1.1 specification. Enabling compression is recommended because it reduces bandwidth usage, and time spent retrieving data.
Note: Payloads less than 1024 bytes will not be compressed.
To enable compression, include the following HTTP header in the request:
The Marketo REST API will compress the response body and include this header:
Here is an example using Curl to call the Get Leads by Filter Type endpoint to retrieve 5 leads:
$ curl -H 'Accept-Encoding: gzip' 'https://123-ABC-456.mktorest.com/rest/v1/leads.json?filterType=id&filterValues=4,5,7,12,13'


In asymmetric algorithm, instead of using one key for encryption and decryption, two different keys are used. Therefore, both keys work together to do the job properly. There is a special mathematical relationship between these two keys. We know these two keys as public key and private key.
If data is encrypted by one of these keys, only the other key is able to decrypt the encrypted data. The mechanism of asymmetric algorithms is simple. This simple method causes the computer processor to allocate a lot of time for encryption and decryption. This is one of the reasons why asymmetric algorithms are used less. We use the asymmetric method more for part of the data and steps of the work. For example, we use these algorithms in the process of authentication or application keys in a symmetric or symmetric method.
Familiarity with public key and private key
One of the reasons why asymmetric encryption is called public key encryption is that the key is publicly available to everyone. On the other hand, asymmetric algorithm is called private key decryption. This is because the private key is not available to anyone. This key is specific to the device itself. For example, in an encrypted and secure site, the public key is used to see the site images by users, and the private key is only in the hands of the server.
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Familiarity with some famous asymmetric key algorithms
- RSA algorithm
Three people or the names of Rivest, Shamir and Adleman use a specific standard for public key encryption. In his algorithm, the length of the key was between 512 and 4096 binary characters. Of course, a threshold was considered for security, which is the length of 1024. It is natural that as the length of the key increases, the security of the key and the probability of its discovery also decrease. Today, this algorithm is used in the authentication process.
- DH algorithm
Diffie-Hellman algorithm is a protocol for key transmission. It is an asymmetric algorithm that allows both devices to send their keys over an insecure platform on the Internet or network. The algorithm itself is asymmetric, but the keys sent by this algorithm are symmetric.
A few points comparing asymmetric algorithms against symmetric algorithms
- Processing in asymmetric algorithms requires more time and processing than symmetric algorithms.
- Asymmetric algorithms are more secure than symmetric algorithms.
- The key length in asymmetric algorithms is longer than in symmetric algorithms, and usually they are between 2048 and 4096 characters long. This is the reason why these algorithms are more secure.
- Asymmetric algorithms are mostly used for special applications such as authentication process or secure key transfer in symmetric method.
In this article, we read that in the asymmetric algorithm method, a key must be shared between the sender and the receiver. While both parties use a pair of keys for encryption. A key is secret and private, and the public key is used for a long time. By reusing the same key pair, the encryption operation is performed well and with sufficient security.


Shop DISH DISH211 4-Device Universal Remote. Free delivery and returns on eligible orders.
The Dish is a patrol aircraft in Mobile Suit Gundam. The Early Warning and Control (EWAC) aircraft that Earth Federation Forces used for reconnaissance and patrol. During the One Year War, they were mainly used in the airspace near bases and served mostly for long-distance target detection. Although it was developed as an early warning machine, it was not able to demonstrate performance under.
I use these RCA jacks to send the audio and video to my TV and to my Panasonic DVD recorder. If your Dish Network is actualy a set top box DVR then it wont have any jacks out other than what you connect to the TV. then you could use the TV RCA out to connect a Digital Set Top Box like my panasonic to. Or the AVS 1 or AVS 2 out on the TV. Connecting a stand alone DVD recorder may not work from.Dish TV DTH Services in LIG Colony, Indore - List of dish TV DTH services, packages, plans near LIG Colony and get dish TV DTH services contact addresses, phone numbers, ratings, reviews and Sulekha score instantly to your mobile.There are a number of places where one can buy a portable satellite dish. For instance, Shaw Direct, Bell, Ground Control, and Amazon all carry portable satellite dishes.
An HD satellite dish allows a customer to receive HD programming in their home via the dish attached to the top of their house. In order for this to be done, correct installation is needed or the.
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When it comes to professionals the dish TV antenna can be adjusted using a signal meter to get the best possible strength but it is also possible for one to do this job without using any device. The following are some steps and ways that will help you adjust a dish TV antenna. 1. Step 1. The first step is to turn on the TV as well as the receiver.
In the filing, Dish complained that T-Mobile inappropriately used Dish’s spectrum as a marketing ploy during COVID-19 lockdowns. “Since T-Mobile gained temporary access to Dish’s 600MHz spectrum on March 15, the company has publicized the capacity benefits of this spectrum in press statements, tweets and advertisements in an apparent effort to acquire new subscribers.
A parabolic dish is a mathematical miracle that gathers and focuses light and sound waves into a single point. They are used in headlights, solar cookers, and satellite TV receivers. The parabolic microphone dish leverages geometry to turn an ordinary microphone into a hyper-directional monster mic. This allows you to recording clear sound at.
Dish Network Satellite TV System DVR-7000. Dish Network Digital Satellite Receiver USER MANUAL DVR-7000.
Tonight when I again attempted to watch another video, the TV screen had an announcement playing telling me that the Netflix was off line while DISH updated listings. So I again turned on my computer to watch my personal Netflix subscription. If the TV isn’t turned off in a particular way, it’s necessary to go through a multistep process to regain operation of the TV. My cable required two.
Homemade ice cream can be made without an ice cream machine, but there is a wide variety of machines available. Some freeze and churn the mixture outside the freezer, while others need to be.
Dish Network Remot, Dish Network Remot Suppliers Directory - Find variety Dish Network Remot Suppliers, Manufacturers, Companies from around the World at networking switch router ,networking equipment ,networking access point, Remote Control.
Photos Video Audio Documents Events Standard Basic Search. Feb 10, 2011. DISH Network Corporation Announces Conference Call for Fourth Quarter and Year End 2010 Financial Results. DISH Network Corporation (Nasdaq: DISH) will host its fourth quarter and year end 2010 financial results conference call on Thursday, Feb. 24, 2011, at noon ET. The dial-in number is (800). Feb 9, 2011. DISH.
The Fire TV Stick is a tiny gizmo that plugs into the HDMI socket on the TV (though you also need to plug the cable into the mains). As well as access to a huge library of movies and TV shows you.


In an effort to provide a better customer service experience for their staff & students, Sheffield Hallam University undertook a project to implement service management for their many IT application systems. This process led to the development of a “service view” which reflects the overall status of each service based on the correlation of results from several network, server and application monitoring solutions. During development, Sheffield Hallam University realised that service status only told part of the story, and that service response time was equally as important.
While the service view dashboard provided an excellent guide to service availability, there were three additional challenges Sheffield Hallam University faced:
Though there were several monitoring solutions in place, none of them could provide the end-to-end service performance metrics that were needed.
Sheffield Hallam University approached Net Consulting to discuss the troubleshooting requirement and came away with a single solution which met all 3 challenges.
After a successful proof-of-concept phase, passive network & application monitoring appliances were installed along with a control unit to provide a holistic business reporting capability.
These appliances were situated in such a way so that all the client/server communication could be analysed between the University’s two data-centres and the various user sites & faculties.
In order to define the “service views” for the University, a modelling exercise had been initiated which mapped physical application servers to logical services. The results of this exercise fed directly into the monitoring appliance configuration. The appliances were then used to help validate the accuracy of the information by verifying the traffic loads & patterns were of the expected quantity.


And 80216e was an enhancement for supporting mobile communications [ramachandran04], which was submitted as a master’s thesis. Msc thesis: design and implementation of a multi-standard interleaver for 80211a, 80211n, 80216e & dvb standards (january 2009) carlos r sánchez-ortiz,. System the basic min of this thesis is to analyze the table 61: performance of ieee 80216e physical layers parameters parameters value. Ganan, imad alhadi omar (2010) performance evaluation of ofdm and modulation techniques in mobile wimax (ieee 80216e) masters thesis, universiti utara.
Functional verification and programming model of winc2r for 80216e mobile wimax protocol by guruguhanathan venkataramanan a thesis submitted to the. Handover mechanism in ieee 80216e, wibro by bhupendra borse wibro network architecture wibro specifications: operating frequency. Reverse engineering: wimax and ieee 80216e a thesis presented to the graduate school of clemson university in partial ful llment of the requirements for the degree.
Ieee 80216e is designed to achieve both high-speed data services and enable mobile users with broadband wireless access solutions in the ieee 80216 standard for. In this thesis the ieee 80216e standard based mobile wimax (worldwide interoperability for microwave access) system is investigated for the purpose of. Study of wimax physical layer under adaptive modulation technique using simulink abdul rehman1, on september 2004in the ieee 80216e-2005, this layer. Signal processing requirements for wimax (80216e) base station (master thesis) m shakeel baig supervisors: yusuf jamal klas brink. Implementation of a wimax simulator the thesis gives an overview about the wimax standard and studies achieved with the 80216e speciﬁcation.Technology and architecture of wimax is the focus of the thesis paper, and more specifically its mobility capabilities mobility version, 80216e. 80216e thesis scalability click here reflective essay introduction examples the advanced placement ap english literature and composition exam exam has. (80216e) base station (master thesis) m shakeel baig supervisors: yusuf jamal klas brink signal processing requirements for wimax (80216e) base station. Is this model for wimax 80216e ofdma uplink or downlink or both i am thinking to make a thesis with scheduling algorithms for wimax with matlab.
Concatenated coding in ofdm for wimax using usrp n210 and gnu radio b siva kumar reddy 1 and b lakshmi 2 (ieee 80216e. On erlang capacity of ieee 80216e networks submitted in partial fulﬁllment of the requirements for the degree of master of technology in in this thesis,. Wimax implementation on gnu radio platform information technology essay the purpose of this thesis is to implement the mobile wimax 80216e as it is. Handovers in mobile wimax master’s thesis submitted in partial fulﬁllment of the requirements 80216e radio interface technology and wimax forum access.
A thesis submitted for the requirements of the degree of master of 252 features of ieee 80216e ofdm phy layer 23 26 wimax mac layer. Dvb-t2, dvb-s2 and ieee 80216e edmond nurellari submitted to the i certify that this thesis satisﬁes the requirements as a thesis for the degree of. This thesis work carries out a study of ieee 80216 standards and mainly concentrates on the group is now working on the 80216e amendment, which covers. Phd dissertations acoustic communication of smart devices, master thesis, seoul national scheme in ieee 80216e mobile broadband wireless.
This€thesis€is€carried€out€in€the€communications€laboratory,€department€of€electrical 215€ieee€80216e2005. Ldpc coded ofdm and it’s application to dvb-t2, dvb-s2 and ieee 80216e - free download as pdf file (pdf), text file (txt) or read online for free since the invention of information theory by shannon in 1948, coding theorists have been trying to come up with coding schemes that will achieve capacity dictated by shannon’s theorem. Worldwide interoperability for microwave access (wimax) is a broadband wireless technology based on ieee 80216-2004 and ieee 80216e-2005 this thesis is a study of wimax technology and market.


IVRS(Interactive Voice Response System)
Through DeGS, Mamta wahan call center with a solution to automate its cab booking process for pregnant women.
Two incoming numbers are being Provided::
IVR would forward calls to drivers present at that location, and upon confirmation sms containing driver and pregnant women details would be exchanged with each other.
- Number A : Will handle inbound calls made by pregnant women / family members.
- Number B : Number for drivers to update their location
Family member (Caller) calls on Number A (Inbound number) to book a cab.
Caller presses 1 if he / she knows the area code, else presses 9 to talk to call center executive
All the drivers present in that area are called in parallel manner
Driver that picks up the call is patched with the caller and they are able to speak
Post call sms containing details of each other are exchanged
In case the caller presses 9, call is transferred to the call center executive
Call center executive speaks to the caller and based on his area code patches the driver by pressing *1# on his / her phone
All three members i.e. caller, driver and call center executive are placed in call
Post call sms containing details of each other are exchange
Driver calls Number B to update their location or checkout
On Calling IVR will play the following message – “Welcome, Please press 1 to update your location, or press 2 to checkout”
On Pressing 1 message following message will be played – “Please enter your location code”
Driver will punch in the location code and confirmation will be played. When driver calls for the first time he will automatically be checked in
On pressing 2, driver would be checked out and system will not contact to allocate a booking
IVR will also play a message – “Thanks for checking out” when driver presses 2


What is 5G？
In mid-October, the iPhone 12 models were announced and 5G support was revealed. From this announcement, the majority of mobile phones are expected to be compatible with 5G, and 5G will become even more popular.
5G stands for "5th Generation". 5G has three key features: "Ultra-high speed", "Ultra-low latency", and "Ultra-many simultaneous connections".
What is telecommunication？
At the start, let's look at the history of communication technology to date.