Apparatus for automatically checking pulse-distortion correction in a signal channel

Claim 2

Apparatus for automatically checking pulse-distortion correction in a signal channel, including means for inserting in the communication signal at the transmitting end individual pulses of constant amplitude and irregularly changing sign to form a composite signal, there being at least two communication pulses between every two inserted individual pulses, input means for receiving the composite signal at the receiving end; a transversal filter coupled to said receiving means and including first register means having plural outputs and means for forming products of time separated portions of the signal derived from said plural output with associated reference signals having regulated voltage values and means for summing said products to develop a corrected signal; a correlation circuit coupled to said summing circuit and having a plurality of outputs for generating said plurality of regulated voltage value signals; means coupled between said input means and said correlation circuit for generating a reference signal to adjust the levels of said reference signals; switch means connected between said reference signal generating means and said correlation circuit for coupling said reference signal to the correlation circuit only during those intervals when said individual pulses are present.

Claim 3

Apparatus in accordance with claim 1 wherein said correlation circuit comprises a second register with plural outputs; a plurality of product generators each coupled to one of said second register plural outputs and said reference signal generating means to produce the reference signals wherein time separated points of at least the received signal freed from distortion by the transversal filter means is used as the first input quantity of the correlation circuit, and the interrupted reference signal itself is used as the second input quantity.

Claim 4

Apparatus in accordance with claim 2 wherein the means for inserting individual pulses includes means for periodically changing the polarity of the individual pulses wherein the change in sign of the individual inserted pulses is arranged to be repeated in periodically recurring portions whereof the length Is not less than the maximum transit time of the transversal filter register means.

Claim 5

Apparatus in accordance with claim 3 further comprising plural filter means each coupled between one of said correlation circuit outputs and said product generating means wherein the autocorrelation function of the inserted pulses is arranged to be small within all time-ranges which are not greater than the maximum transit time of the transversal filter.

Claim 6

Apparatus in accordance with claim 1 comprising a communications channel and wherein the means for inserting individual pulses comprises a noise generator means and second switch means for selectively coupling either the communication signal or the generator means to the communications channel; said first and second switch means operating in synchronism.

Claim 7

Apparatus in accordance with claim 1 comprising a communications channel and wherein the means for inserting the individual pulses includes means for generating signals which take the form of pulses of a separate data signal to be transmitted, and second switch means for selectively coupling either the communication signal or the generator means to the communications channel; said first and second switch means operating in synchronism.

Claim 8

Apparatus in accordance with claim 1 including a communications channel and wherein the means for inserting individual pulses includes generator means for generating a pulse-train comprised of a quasi-statistical pulse sequence, and second switch means for selectively coupling either the communication signal or the generator means to the communications channel; said first and second switch means operating in synchronism.

Claim 9

Apparatus in accordance with claim 7 wherein the means for inserting individual pulses comprises a shift register having plural outputs; summing means for summing selected ones of said outputs and coupling the generated sum to the input of the register, the individual pulses being taken from the output of said summing means.

Claim 10

Apparatus in accordance with claim 8 wherein said summing means is a modulo-2 adder.

Claim 11

Apparatus in accordance with claim 1 wherein the communication pulses are generated by means for generating communicating pulses of constant amplitude, said generating means including means for changing the sign of the communication pulses according to the information to be transmitted.

Claim 12

Apparatus in accordance with claim 1 further including means for quantifying the amplitude of the communication pulses in a predetermined gradation.

Claim 13

Apparatus in accordance with claim 1 wherein the communication pulses are generated by means which are amplitude-modulated in accordance with the information being transmitted.

Claim 14

Apparatus in accordance with claim 1 wherein said reference signal generating means comprises amplitude limiting means.

Claim 15

Apparatus in accordance with claim 1 wherein said reference signal generating means comprises pulse-generator means which is synchronized with said first switch means to generate the inserted individual pulses.

Claim 16

Apparatus in accordance with claim 14 wherein said first pulse generator means further comprising switch means for initially coupling the first pulse-generator means with said input means for accepting the received signal, means for comparing the received signal with the output of said first pulse generator means and for operating said switch means to decouple the input means from the input of said first pulse generator means and couple the output of said pulse generator means to its input, whereby said first pulse generator means is capable of self-sustaining operation after synchronism has been detected by said comparison means.

Claim 17

Apparatus in accordance with claim 15 wherein the switch-over to self-sustaining operation is controlled by counting means coupled to said comparison means whereby switch-over occurs as soon as agreement exists between inserted pulses in the received signal and the pulses in the return channel of the geneRator for a duration corresponding to at least the transit time of a signal through the pulse generator.

Claim 18

Apparatus in accordance with claim 14, further comprising second pulse generator means at said sending end for generating said individual pulses, said second pulse generator means being identical to said first pulse generator means.

Claim 19

Apparatus in accordance with claim 1 including correcting means coupled to said transversal filter summing means and said switching means wherein the reference pulses obtained by interrupting the reference signal during the communication pulses are generated by said correcting means and applied to said correlation means for correcting low signal frequencies of the corrected signal.

Claim 20

Apparatus in accordance with claim 1 wherein at least a part of the inserted individual pulses is used as a master pulse sequence for obtaining crypto signals in encrypted communication transmission.

Claim 21

Apparatus in accordance with claim 1 wherein the correlation circuit comprises a multi-stage shift-register to which the first input signal is fed, and a plurality of individual correlators each coupled to respective outputs of the shift-register and to said switch means whereof each forms the mean product of voltage derived from one shift-register output and a second input signal coupled to each of said correlators.

Claim 22

Apparatus in accordance with claim 20 further comprising a difference circuit coupled to summing means and said reference signal generating means wherein the first input signal of the correlation circuit consists of the difference between the de-distorted received signal and the reference signal, and the second input signal consists of the reference signal developed by the reference signal generating means interrupted by said switch means during the communication pulses.

Claim 23

Apparatus in accordance with claim 1 comprising means coupled to said correlation circuit for amplitude limiting at least one input signal applied to the correlation circuit.

Claim 24

Apparatus wherein compensation for linear distortion occurring within a first transmission channel is arranged to be supplemented by compensation for crosstalk interference caused by coupling between first and second pulse channels, comprising first and second apparatus each being of the type set forth in claim 1 for distortion correction of said first and second channels respectively and wherein the received signal of the second channel is fed to the transversal filter of said second apparatus, the regulating voltage for controlling the coupling values of the second apparatus transversal filter being obtained from the second apparatus correlation circuit, the input signals for which comprise the already de-distorted output signal and a reference signal obtained from the second apparatus switch means which provides the inserted individual pulses of the second channel, said reference signal being arranged to be interrupted during the communication pulses of the second channel and wherein the inserted pulses of the first channel from which distortion is to be removed and of the second channel exhibit no cross-correlation.

Claim 25

Apparatus in accordance with claim 1 including means for generating additional auxiliary pulses of constant amplitude are transmitted in place of the communication pulses in a first phase of equalisation and corresponding reference pulses are used at the receiving end.

Claim 26

Apparatus in accordance with claim 1 wherein said correlation means comprised a plurality of individual correlators wherein means are provided at the beginning of equalisation for reducing the number of correlators operating in the correlation circuit and thereby correspondingly reducing the number of coupling values in the transverse filter, and means for increasing the number of individually effective correlators and of corresponding coupling values in the course of equalisation.

Claim 27

Apparatus for automatically checking pulse-distortion correction in a signal channel, incLuding means for inserting in the communication signal at the transmitting end individual pulses of constant amplitude and irregularly changing sign to form a composite signal, there being at least two communication pulses between every two inserted individual pulses, input means for receiving the composite signal at the receiving end, a transversal filter coupled to said receiving means and including first register means having plural outputs and means for forming products of time separate portions of the signal derived from said plural output with associated reference signals having regulated voltage values and means for summing said products to develop a corrected signal; a correlation circuit coupled to said input means and having a plurality of outputs for generating said plurality of regulated voltage value signals, means coupled between said input means and said correlation circuit for generating a reference signal to adjust the levels of said reference signals; switch means connected between said reference signal generating means and said correlation circuit for coupling said reference signal to the correlation circuit only during those intervals when said individual pulses are present.

Claim 28

Apparatus for automatically checking pulse-distortion correction in a signal channel, incLuding means for inserting in the communication signal at the transmitting end individual pulses of constant amplitude and irregularly changing sign to form a composite signal, there being at least two communication pulses between every two inserted individual pulses, input means for receiving the composite signal at the receiving end, a transversal filter coupled to said receiving means and including first register means having plural outputs and means for forming products of time separate portions of the signal derived from said plural output with associated reference signals having regulated voltage values and means for summing said products to develop a corrected signal; a correlation circuit coupled to said input means and having a plurality of outputs for generating said plurality of regulated voltage value signals, means coupled between said input means and said correlation circuit for generating a reference signal to adjust the levels of said reference signals; switch means connected between said reference signal generating means and said correlation circuit for coupling said reference signal to the correlation circuit only during those intervals when said individual pulses are present.

Claim 29

Apparatus in accordance with claim 26 comprising difference means coupled between the output of the transversal filter summing means and said interrupting means wherein the difference between the corrected received signal and the reference signal, which difference is interrupted during the communication pulses, serves at the second input quantity to said correlation means.

Claim 30

Apparatus in accordance with claim 26 wherein the correlation circuit includes means for directly employing the outputs of said first register means in producing said regulated voltage signals.

Claim 31

Apparatus for pulse distortion correction in a signal channel through which communication signals are transmitted comprising: means at an input end for inserting a pulse of constant amplitude and irregularly changing sign between said communication signals at least two communication pulses are each separated from the other by one of said inserted pulses; transversal filter means having a first input coupled to said channel for generating distortion corrected communication pulses; correlation means coupled to the output of said transversal filter means and having a plurality of outputs; means coupled to one output of said correlation means outputs for generating a reference signal; said correlation means including a first plurality of product means each responsive to an associated one of said outputs and said reference signal for generating a regulating voltage; said transversal filter means including means responsive to said regulating voltages and said incoming signal for forming a plurality of product signals and means for summing said product signals to obtain said distortion corrected communication signals; means coupled between said reference signal generating means and said first plurality of product means responsive to said constant amplitude pulses for interrupting said reference signal only during the occurrence of said communication pulses.

Claim 32

Apparatus for pulse distortion correction in a signal channel through which communication signals are transmitted comprising: means at an input end for inserting a pulse of constant amplitude and irregularly changing sign between said communication signals at least two communication pulses are each separated from the other by one of said inserted pulses; transversal filter means having a first input coupled to said channel for generating distortion corrected communication pulses; correlation means coupled to the output of said transversal filter means and having a plurality of outputs; means coupled to one output of said correlation means outputs for generating a reference signal; said correlation means including a first plurality of product means each responsive to an associated one of said outputs and said reference signal for generating a regulating voltage; said transversal filter means including means responsive to said regulating voltages and said incoming signal for forming a plurality of product signals and means for summing said product signals to obtain said distortion corrected communication signals; means coupled between said reference signal generating means and said first plurality of product means responsive to said constant amplitude pulses for interrupting said reference signal only during the occurrence of said communication pulses.

Claim 33

The apparatus of claim 29 wherein said reference signal generating means comprises multi-stage shifting means having a plurality of outputs; means coupled to at least two selected ones of said outputs for forming a sum; switch means having a first position for coupling said communications channel to the input of said shifting means and a second position for decoupling said channel from said shifting means and coupling the output of said summing means to the input of said shifting means for self-sustained operation thereof; comparison means coupled to said summing means and said channel for operating said switch means to said second position only when said signals compare.

Claim 34

The apparatus of claim 30 wherein said comparison means further includes counting means for controlling operAtion of said switch means to said second position only after a predetermined number of pulses of said shifting means and said channel are in synchronism.

Claim 35

A distortion correction circuit for correcting distortion of communication signals transmitted through a channel and together with constant amplitude alternating polarity reference pulses each being interspersed between two communication pulses comprising: a transversal filter including: a multi-stage shif means having a plurality of outputs; a plurality of product forming means having a first input coupled to an associated output of said shift means; a second input and a single output for each product forming means and summing means for summing the outputs of said product forming means; a correlation circuit comprising: second multi-stage shift means having a plurality of outputs; a second plurality of product forming means each having a first input coupled to an associated one of said shift means outputs, a second input and a single output for each product forming means; and means for generating a reference signal from said channel; the input of said second shift means being coupled to the output of said summing means; the second inputs of said first product forming means being coupled to associated outputs of said second product forming means; means coupled between the second inputs of each of said product forming means and said reference signal generating means for interrupting said reference signal only during each communication pulse.

Claim 36

A distortion correction circuit for correcting distortion of communication signals transmitted through a channel and together with constant amplitude alternating polarity reference pulses each being interspersed between two communication pulses comprising: a transversal filter including: a multi-stage shif means having a plurality of outputs; a plurality of product forming means having a first input coupled to an associated output of said shift means; a second input and a single output for each product forming means and summing means for summing the outputs of said product forming means; a correlation circuit comprising: second multi-stage shift means having a plurality of outputs; a second plurality of product forming means each having a first input coupled to an associated one of said shift means outputs, a second input and a single output for each product forming means; and means for generating a reference signal from said channel; the input of said second shift means being coupled to the output of said summing means; the second inputs of said first product forming means being coupled to associated outputs of said second product forming means; means coupled between the second inputs of each of said product forming means and said reference signal generating means for interrupting said reference signal only during each communication pulse.

Claim 37

The apparatus of claim 32 wherein said reference signal generating means comprises a pulse generator and switch means for selectively coupling said pulse generator to said channel or to itself for self-excitation; means for operating said switch means to place said pulse generator in the self-exciting state when the signals in said channel and the output of said pulse generator are in synchronism.