System and method of channel performance monitoring

Claim 1

A communication channel performance monitoring system for determining the impulse response of a communication channel having an input and output by employing polarity coincidence correlation for obtaining measurement of cross correlation between the channel output signal and a delayed locally generated pseudorandom noise sequence probe signal and comprising first generating means in communication with an input to a communication channel being monitored for generating clock pulses and a first two-level pseudorandom noise sequence probe pulse signal in response to the clock pulses wherein the leading edges of the probe signal pulses coincide with the clock pulses and the periods of the probe signal pulses are random integral numbers of a clock pulse period, summing means connected between an output of said first generating means and the input to the communication channel for summing the probe signal and a data signal simultaneously transmitted through the channel, the probe signal being uncorrelated with the data signal and having a voltage level as low as one and one-hundredth of the amplitude of the data signal to thereby minimize interference with the data signal transmission to a negligible amount, signal limiting means in communication with an output of the communication channel for developing a two-level signal being a function of the relative magnitudes of the channel output signal, second generating means for generating clock pulses and a second probe signal in response thereto corresponding to the first probe signal but with a controllably variable time delay Tau , means connected to the output of said signal limiting means and said second generating means for comparing the signal outputs thereof on a bit-by-bit basis with respect to the clock pulses, the output signal of said comparing means being at a first voltage level when the levels of the delayed probe signal and an output of said signal limiting means agree and being at a second voltage level when the levels disagree, and reversible counter means connected to an output of said comparing means for establishing a count which is the difference between the total number of agreements and total number of disagreements at the output of said comparing means over a particular time interval and from which a measurement of the cross correlation between the signal at the output of the communication channel and the probe signal may be determined.

Claim 11

A method for monitoring the performance of a communication channel by determining the impulse response thereof employing polarity coincidence correlation for obtaining measurement of cross correlation between the channel output signal and a delayed locally generated pseudorandom noise sequence probe signal and comprising the steps of generating clock pulses and a first pseudorandom noise sequence voltage probe pulse signal in response to the clock pulses wherein the leading edges of the probe signal pulses coincide with the clock pulses and the periods of the probe signal pulses are random integral numbers of a clock pulse period, passing the first probe signal through the communication channel being monitored, limiting the signal output of the communication channel by developing a two-level signal as a function of the relative magnitudes of the channel output signal, generating a second probe signal corresponding to the first pseudorandom noise sequence signal but with a first variable time delay, comparing the delayed second probe signal and the two-level limited signal on a bit-by-bit basis with respect to the clock pulses, the signal comparison developing an output signal at a first voltage level when the levels of the delayed second probe signal and limited signal agree and at a second voltage level when the levels disagree, generatiNg a count which is the difference between the total number of agreements and total number of disagreements of the compared delayed probe signal and limited signal over a particular time interval for a first selected delay in the second probe signal, and generating a count which is the sum of the total number of agreements and total number of disagreements and is equal to the number of clock pulses generated over the particular time interval to thereby determine a first measurement of the cross correlation between the signal at the output of the communication channel and the pulse signal by dividing the difference count by the sum count.

Claim 12

A method for monitoring the performance of a communication channel by determining the impulse response thereof employing polarity coincidence correlation for obtaining measurement of cross correlation between the channel output signal and a delayed locally generated pseudorandom noise sequence probe signal and comprising the steps of generating clock pulses and a first pseudorandom noise sequence voltage probe pulse signal in response to the clock pulses wherein the leading edges of the probe signal pulses coincide with the clock pulses and the periods of the probe signal pulses are random integral numbers of a clock pulse period, passing the first probe signal through the communication channel being monitored, limiting the signal output of the communication channel by developing a two-level signal as a function of the relative magnitudes of the channel output signal, generating a second probe signal corresponding to the first pseudorandom noise sequence signal but with a first variable time delay, comparing the delayed second probe signal and the two-level limited signal on a bit-by-bit basis with respect to the clock pulses, the signal comparison developing an output signal at a first voltage level when the levels of the delayed second probe signal and limited signal agree and at a second voltage level when the levels disagree, generatiNg a count which is the difference between the total number of agreements and total number of disagreements of the compared delayed probe signal and limited signal over a particular time interval for a first selected delay in the second probe signal, and generating a count which is the sum of the total number of agreements and total number of disagreements and is equal to the number of clock pulses generated over the particular time interval to thereby determine a first measurement of the cross correlation between the signal at the output of the communication channel and the pulse signal by dividing the difference count by the sum count.