Automatic retrain method for a full duplex modem having an echo canceller and an equalizer
AssigneeNEC Corporation
InventorMasayoshi Hiraguchi
Life of this patent
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Abstract
The invention relates to an automatic retrain method applicable to full duplex data transmission modems which shortens the conventional protocol for retraining in the instance where signal reception can be improved by retraining only the automatic equalizers of the linked modems. If the retrain-initiating modem fails to detect a retrain signal from the linked modem within a predetermined time after transmitting its own retrain signal, the conventional retraining protocol is then adopted in order to retrain both the echo cancellers and the automatic equalizers of the linked modems.
Claims5
A retrain method for first and second modems operatng in a full duplex data transmission mode via a two wire circuit, each of the first and second modems including modulating means for modulating input data to produce a modulated signal, and echo canceller for cancelling an echo produced in response to the modulated signal, an equalizer for equalizing waveform distortion produced on a received modulated signal transmitted through a transmission line, and demodulating means for demodulating the received modulated, equalized signal into the input data, said retrain method comprisng the steps of:
- detecting deterioration of the received modulated signal from said second modem,
- suspending data transmission from said first modem in response to the detection of deterioration and transmitting, at least once, a first training signal having a predetermined pattern and time period,
- suspending data transmission from said second modem in response to said first training signal and transmitting, once, a second training signal having a predetermined pattern and time period, and
- automatically training only said equalizers of said first and second modems in response to the second and first training signals, respectively.
A retrain method for first and second modems arranged for full duplex data transmission via a two wire circuit, said modems being of the type including echo cancellers and distortion equalizers, comprising:
- detecting deterioration of a signal received at said first modem;
- suspending signal transmission from said first modem;
- transmitting a first retrain signal from said first modem;
- suspending signal transmission from said second modem;
- transmitting a second retrain signal from said second modem;
- and
- automatically training only equalizers of said first and second modems in response to said second and first retrain signals, respectively.
Dependencies are inferred from the claim text.