High speed data modem using digital signal processor

The design and construction of a 9600 bit/s modem, which is compatible with the CCITT Recommendation V.29, are presented along with experimental results. A digital signal processor with a high-speed multiplier is employed for the main modem functions, such as automatic equalization and low-pass filtering. Such modem functions as automatic gain control and timing recovery are flexibly and adaptively implemented by digital signal processor and microprocessor software. The prototype modem gives good performance at S/N = 20 dB and over a 90-deg peak-to-peak maximum allowable carrier phase jitter angle at 50 Hz.