Software for Telecoms & Audio
V.26bis Modem DSP C Code
implements the ITU Data Modem functions V.26bis & V.26, which provide
data transmission at rates of 2.4 & 1.2kb/s in half-duplex over the
telephone network and full-duplex for 4-wire leased line operation. In
both cases, an optional independently-controlled backward channel can
be incorporated for rates of up to 75b/s.
at the sample interface, the code can operate at 8.0kHz and 9.6kHz sample
rates. Transmit and receive samples are transferred on a common clock,
to which the transmit clock is synchronised. The receive clock is interpolated
in the code for synchronisation to the far-end modem. At the data interface,
data is transferred in buffers under pointer control via subroutine calls.
Performance: over flat channels, near matched-filter performance is obtained. SNR for 10-6 Error Rate (4kHz BW noise):
#example figures from compiling for the TI TMS320C5000(C55x) DSP processor
Availability: NOW - sale is under licence - integration support offered