CW radar system

The method of measuring distance to a first object which is moving relative to a second, said method comprising the steps of:

• transmitting a radar signal from the second object toward the first object, the radar signal comprising a phase modulated carrier the modulation of which represents a repetitive digital code;
• simultaneously receiving echoes of said radar signal returning from the first object to the second object;
• multiplying the received echo by a sample of said carrier to derive a product signal;
• multiplying the product signal by said repetitive digital code to derive a second product signal;
• separating out the low frequency component of said second product signal to develop an output signal;
• and
• developing and transmitting a telemetry signal by modulating said radar signal as a function of said output signal.

The method of measuring distance between first and second relatively moving objects which comprises the steps of transmitting from the second object toward the first object a signal comprising a phase modulated carrier the modulation of which represents a repetitive digital code;

• simultaneously applying a sample of the carrier to a detector capable of multiplying said sample and echoes of said signal returned from said first object to said second object;
• receiving and applying to said detector echoes of said signal returned to said second object from said first object;
• developing a plurality of correlation signals each constituting a delayed replica of said repetitive digital code;
• multiplying each of said correlation signals by signals corresponding to said product signals to derive, on the occasion of the return of an echo, a second product signal;
• separating out the low frequency components of said second product signals to develop output signal corresponding to said second output signals, respectively;
• and
• modulating said carrier with each of said output signals whereby said signal includes information about the presence of echoes at said second object and the time required for said signal to traverse the distance from said second object to said first object and to return to said second object as an echo.

In combination:

• an oscillator;
• a phase modulator;
• a transmitting antenna;
• a receiving antenna;
• a first detector;
• a high pass filter;
• a correlator comprising a second detector and a Doppler filter in the output circuit of said second detector;
• a repetitive digital code generator;
• means for applying the output of said oscillator and the output of said code generator to said phase modulator;
• means for applying the output of said phase modulator to said transmitting antenna;
• means for applying echoes of signals transmitted by said transmitting antenna and a portion of the output of said oscillator to said first detector;
• means for applying the output of said first detector to said high pass filter;
• means for applying the output of said high pass filter and a portion of the output of said code generator to the detector of said correlator;
• means for detecting the output of said Doppler filter of said correlator;
• and
• means for modulating the output of said phase modulator as a function of the output of said Doppler filter to provide a telemetry signal.

In combination:

• an oscillator;
• a phase modulator;
• a transmitting antenna;
• a receiving antenna;
• a product detector;
• a Doppler filter;
• a repetitive digital code generator;
• means for applying the output of said oscillator and the code from said generator to said phase modulator;
• means for applying the output of said phase modulator to the transmitting antenna;
• means for applying echoes of signals transmitted by said transmitting antenna and a delayed sample of said code to said product detector;
• means for applying the output of said detector to said Doppler filter;
• and
• telemetering means for modulating the output of said oscillator as a function of the output of said Doppler filter.