Data modem receiver

Details Data modem receiver Data modem receiver

1988-08-29

1989-07-18

Safourek, Benedict V.

Pulse or digital communications

Repeaters

Testing

34082574, 36472409, H04B 310

Patent

active

048499897

ABSTRACT:
In a data modem receiver (80) the received signal is digitized in an A/D-converter (84), the output of which is applied to notch filter means (88, 96) which eliminates secondary channel signals, and which applies an output signal to a pair of IIR filters (112, 116), responsive to the frequency components present in a training signal. The values of the IIR filter output sigals are determined and compared with a pair of threshold levels provided by a threshold setter circuit (152) responsive to the peak received signal level to detect the receipt of a training signal. In response to the detection of a training signal, DFT calculations are initiated for timing recovery and modem address identification, using samples stored in a buffer shift register (206). A gain control circuit (220) is located subsequent to a band-pass filter (212) coupled to the buffer shift register (206).

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