Pulse or digital communications – Transceivers – Modems
Patent
1996-10-31
2000-03-14
Chin, Stephen
Pulse or digital communications
Transceivers
Modems
375229, 375231, H04B 138, H04L 516
Patent
active
060382511
ABSTRACT:
A modem communication system with receiving and transmission paths includes a direct equalizer system having an adaptive filter (1532) in the transmission path to compensate for frequency distortion of the communication channel. The transmitter filter coefficients are adapted by a filter coefficient calculator (1528), under control of a data detector (1526) which detects incoming data in the receiving path. A switch (1534) is controlled by status of a transmit output data buffer to multiplex either the training sequence or output data into the transmission path. When the buffer is idle, the training sequence generator (1540) is linked to a digital-to-analog (D/A) converter (1536) and line driver (1538). The receiving path includes an isolation switch (1520), a receiver amplifier (1522) and a slicer (1524). The receiver correlates the received training sequence with a known training sequence and updates the equalizer filter coefficients using an adaptation algorithm, such as a least mean squared algorithm. A first embodiment utilizes a high speed digital programmable filter (1532). Another embodiment utilizes a data buffer (1533) which is periodically filled with data filtered by a digital signal processor (DSP).
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Chin Stephen
Donaldson Richard L.
Franz Warren L.
Ghayour Mohammad
McClure C. Alan
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