V.Modem Algorithms
V.17
V.17 – Availability: C64x, C55x, C54x, Arm9E
This half-duplex modem is intended for use in FAX applications. It employs trellis coded modulation at data signaling rates of 7.2, 9.6, 12, and 14.4 kbit/s with a symbol rate of 2400 symbols per sec. The modulation methods are rectangular 16-QAM at 7.2 kbit/s, modified cross 32-QAM at 9.6 kbit/s, rectangular 64 -QAM at 12 kbit/s, and modified cross 128-QAM at 14.4 kbit/s. It includes an automatic adaptive equalizer, long-train and re-sync sequences, and optional Talker Echo Protection tone generation.rm
V.21
V.21 – Availability: C64x, C55x, C54x, Arm9E
This modem is used in fax and v.34 startup applications. It is a 2 channel modem operating at a data signaling rate of 300 bit/s with a symbol rate of 300 symbols/sec. The modulation method is continuous phase frequency shift keying (CP-FSK).
V.27
V.27 – Availability: C64x, C55x, C54x, Arm9E
This half/full duplex modem is used in half duplex FAX applications, and full duplex in leased-line applications. It employs QPSK and 8-PSK modulation at data signaling rates of 2.4 and 4.8 kbits/sec with symbol rates of 1200 and 1600 symbols/sec respectively. It includes an automatic adaptive equalizer, long and short training sequences, and optional Talker Echo Protection tone generation.
V.29
V.29 – Availability: C64x, C55x, C54x, Arm9E
This half duplex modem was intended for 4 wire operation but is used in FAX applications. It employs an unusual amplitude-phase shift modulation scheme at 4.8, 7.2, and 9.6 kbits/sec with a symbol rate of 2400 symbols/sec. It includes an automatic adaptive equalizer, long-train and re-sync sequences, and optional Talker Echo Protection tone generation.
V.22bis
V.22bis – Availability: C64x, C55x, C54x, Arm9E
This split-band data modem supports full duplex data transfer at 1200 and 2400 bit/s with a symbol rate of 600 symbols/sec. The modulation methods are differential QPSK at 1200 bit/s, and rectangular 16-QAM at 2400 bit/s.
V.32bis
V.32bis – Availability: C64x, C55x, C54x, Arm9E
This full duplex echo canceller data modem operates with trellis-coded modulation at 4.8, 7.2, 9.6 (TCM and non-TCM), 12.0, and 14.4 kbit/sec. The symbol rate for all data signaling rates is 2400 symbols/sec. The modulation methods are: QPSK at 4.8 kbit/s, rectangular 16-QAM at 9.6 kbit/s non-trellis coded modulation (TCM), rectangular 16-QAM at 7.2 kbit/s, modified cross 32-QAM at 9.6 kbit/s, rectangular 64 -QAM at 12 kbit/s, and modified cross 128-QAM at 14.4 kbit/s.
