Abstract: A random signal radar unit transmits a variable signal modulated by random noise (at 41). The return signal from the target area is correlated (at 61) with a sample of the transmitted signal, effectively compressing the spread spectrum waveform into a narrow band signal. The result is a covert high resolution radar which can be instrumented to operate in a number of single-or multi-mode configurations. By randomly varying biphase modulation (at 41, 35) and by down beating (at 49) the echo signal with the modulation delayed by a time equivalent to that of a leakage delay, a random signal is produced (at 35, 39) in which leakage return signals are readily filtered (at 53, 59).

Abstract: A random signal radar unit transmits a variable signal modulated by random noise (at 35). The return signal from the target area is correlated (at 61) with a sample of the transmitted signal, effectively compressing the spread spectrum waveform into a narrow band signal. The result is a covert high resolution radar which can be instrumented to operate in a number of single-or multi-mode configurations. By randomly varying biphase modulation (at 41, 35) and by modulating (at 49) the echo signal with the modulation delayed by a time equivalent to that of a leakage delay, a random signal is produced (at 35, 39) in which leakage return signals are readily filtered (at 53, 59).

Abstract: A random signal radar unit transmits a variable signal modulated by random noise (at 35). The return signal from the target area is correlated (at 61) with a sample of the transmitted signal, effectively compressing the spread spectrum waveform into a narrow band signal. The result is a covert high resolution radar which can be instrumented to operate in a number of single-or multi-mode configurations. By randomly varying biphase modulation (at 41, 35) and by, modulating (at 49) the echo signal with the modulation delayed by a time equivalent to that of a leakage delay, a random signal is produced (at 35, 39) in which leakage return signals are readily filtered (at 53, 59).

Abstract: A variable digital delay circuit is disclosed which utilizes a shift register to periodically sample a signal to be delayed and after a predetermined number of samples are collected as a group of zeros and ones making up a binary word the word is stored in parallel in a memory. After each binary word is stored in a memory a binary word previously stored in the memory is read out into a buffer store from which each individual bit is sequentially read out using a multiplexer at the same rate that the bits were originally taken to thereby recreate the original signal samples. The time delay is determined by how long the previously stored binary word being read out has been stored in the memory.