Level independent automatic cable equalizer
First Claim
1. An automatic cable equalizer for compensating for a variable level input signal with possibly degraded rise and fall times, the equalizer comprising:
- equalizer means, having an input and an output, with the input coupled to receive the variable level input signal, the equalizer means containing amplifying means, high frequency gain boosting means and clipping means, the clipping means having a clipping control input coupled to receive a clipping control signal;
signal level detecting means coupled to monitor the variable level input signal and for producing the clipping control signal, the clipping control signal being proportional to the peak level of the rectified low frequency content of the variable level input signal.
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Accused Products
Abstract
A multiple section cable equalizer with a signal level detector produces a clipping control signal for amplifiers in each equalizer section, so that a variable level input signal is restored to an equalized output signal that is free of distortion and attendant bit errors. A fixed reference clipping stage after the last equalizing stage produces a signal clipped to a final output level. A feedback path restores DC and low frequencies lost due to AC coupling. A test output stage permits monitoring of the operation of the equalizer stages. The signal level detector contains (in series), a differential amplifier with low pass filtering, a balanced modulator detector, a voltage amplifier, a comparator and peak detector, a transconductance amplifier and a plurality of current mirrors operatively connected to determine a difference current from the output of the transconductance amplifier and convert this to a clipping control signal voltage level. A defeat comparator monitors the output of the comparator and peak detector and replaces the variable difference current with a fixed reference current when an external capacitor used by the peak detector appears to be shorted.
41 Citations
10 Claims
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1. An automatic cable equalizer for compensating for a variable level input signal with possibly degraded rise and fall times, the equalizer comprising:
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equalizer means, having an input and an output, with the input coupled to receive the variable level input signal, the equalizer means containing amplifying means, high frequency gain boosting means and clipping means, the clipping means having a clipping control input coupled to receive a clipping control signal; signal level detecting means coupled to monitor the variable level input signal and for producing the clipping control signal, the clipping control signal being proportional to the peak level of the rectified low frequency content of the variable level input signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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Specification