Message transmission system with pulse compression

Claim 1

A message transmission system which utilizes pulse code modulation wherein the code words are comprised of code elements with a duration Tau and the code elements comprise a discontinuous modulation function in the form of one of two possible states, one of these states being a time dependently rising frequency function and the other of these states being a time dependently falling frequency function, the system comprising a transmitter including means for effecting said rising and falling frequency functions for each individual code element and a receiver including an input and two parallel paths connected to said input, one of said paths including a pulse compression filter for said time dependently rising frequency function and the other of said paths including a pulse compression filter for the time dependently falling frequency function, each of said filters connected to said input, a pair of detectors connected to respective ones of said filters, a common subtraction device connected to the outputs of said detectors of both of said paths for reversing the sign of the signals of one of said paths, a delay member connected to said subtraction device and having taps shifted in time by the interval Tau , a plurality of monitoring circuits including one type of monitoring circuit for allowing passage of signals compressed in one of said paths and a second type of monitoring circuit foR allowing passage of signals compressed in the other of said paths, said monitoring circuits connected to said taps of said delay member, the distribution thereof being the same as the distribution of said two states in the transmitted signal and therefore maintaining a second pulse compression of the received signal, a common addition network connected to the outputs of said monitoring circuits for receiving the signals passed thereby and responsive to such signals to provide a strongly pronounced pulse only for such code words of which the elements thereof contain the modulation function corresponding to the distribution of the types of monitoring circuits connected to said taps of said delay member.

Claim 3

A method of transmitting code words in a system, digitally, wherein the code words are comprised of a plurality of code elements each having a duration Tau , and the code elements comprise one of two possible states, one of these states being a time dependently rising frequency function and the other of these states being a time dependently falling frequency function, comprising the steps of: transmitting the code words; receiving the code words; and compressing the received code words on the basis of the time dependent rising and falling frequency functions thereby producing a first compressed signal and compressing said first compressed signal digitally to improve the output signal to noise ratio.

Claim 4

A method of transmitting code words in a system, digitally, wherein the code words are comprised of a plurality of code elements each having a duration Tau , and the code elements comprise one of two possible states, one of these states being a time dependently rising frequency function and the other of these states being a time dependently falling frequency function, comprising the steps of: transmitting the code words; receiving the code words; and compressing the received code words on the basis of the time dependent rising and falling frequency functions thereby producing a first compressed signal and compressing said first compressed signal digitally to improve the output signal to noise ratio.

Claim 5

A method of transmitting code words in a secondary radar system, digitally, wherein the code words are comprised of a plurality of code elements each having a duration Tau , and the code elements comprise one of two possible states, one of these states being a time dependently rising frequency function and the other of these states being a time dependently falling frequency function, comprising the steps of: transmitting the code words; receiving the code words; and compressing the received code words on the basis of the time dependent rising and falling frequency functions thereby producing a first compressed signal, and compressing said first compressed signal digitally to improve the output signal to noise ratio.

Claim 6

A method of transmitting code words in a secondary radar system, digitally, wherein the code words are comprised of a plurality of code elements each having a duration Tau , and the code elements comprise one of two possible states, one of these states being a time dependently rising frequency function and the other of these states being a time dependently falling frequency function, comprising the steps of: transmitting the code words; receiving the code words; and compressing the received code words on the basis of the time dependent rising and falling frequency functions thereby producing a first compressed signal, and compressing said first compressed signal digitally to improve the output signal to noise ratio.