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This is a list of interface bit rates, ... which should be more concerned with price per port to support the interface, wattage and heat considerations, and total ...
Bit rates commonly supported include 75, 110, 300, 1200, 2400, 4800, 9600, 19200, 38400, 57600 and 115200 bit/s. [19] Many of these standard modem baud rates are multiples of either 1.2 kbps (e.g., 19200, 38400, 76800) or 0.9 kbps (e.g., 57600, 115200). [23] Crystal oscillators with a frequency of 1.843200 MHz are sold specifically for this ...
V.32 (11/88) is an ITU-T recommendation for a modem operating as full-duplex on a 4-wire circuit, or half-duplex on a two-wire circuit, allowing bidirectional data transfer at either 9.6 kbit/s or 4.8 kbit/s at a symbol rate of 2,400 baud instead of the 600 baud of the V.22 standards. [2]
For example, in a 64QAM modem, M = 64, and so the bit rate is N = log 2 (64) = 6 times the baud rate. In a line code, these may be M different voltage levels. The ratio is not necessarily an integer; in 4B3T coding, the bit rate is 4 / 3 of the baud rate. (A typical basic rate interface with a 160 kbit/s raw data rate operates at 120 kBd.)
For this reason, the baud rate value will often be lower than the gross bit rate. Example of use and misuse of "baud rate": It is correct to write "the baud rate of my COM port is 9,600" if we mean that the bit rate is 9,600 bit/s, since there is one bit per symbol in this case. It is not correct to write "the baud rate of Ethernet is 100 ...
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. The introduction of these higher-speed systems also led to the development of the digital fax machine during the 1980s.
Using trellis encoding, HST provided 9,600 bit/s speeds, leapfrogging the standards efforts and offering four times the performance for about twice the price of a 2400 bit/s model. In 1989 HST was expanded to 14.4 kbit/s, 16.8 kbit/s in 1992, [ 6 ] and finally to 21 kbit/s and 24 kbit/s.
Two versions of the SpeedModem were released in 1991, the Champ with an introductory price of $169, and Combo at $279 which added 9,600 bit/s Group III fax support. [2] The modem supported MNP5 data compression and their own format, CSP-3, which they claimed was as effective as v.42bis .