Effects of unanticipated VSWR reflection and delay on range correlation performance

Many parameters can affect the range correlation and range measurement during a spacecraft's normal range operation as well as in a space vehicle range testing environment. These parameters include the unanticipated voltage standing wave ratio (VSWR) reflection, multipath, flutter, space or hardware group delay, and ionospheric propagation delay, which can distort the amplitude and phase of the received pseudorange noise (PRN) range signal. Many other known or deterministic parameters, such as range receiver average noise - from local oscillator (LO) and quantization average noises, and Doppler delay, can be removed a priori from the range calculation by using software. This paper deals with correlation of the PRN range code in the correlation receiver relative to the 500 kHz clock in the reference clock receiver. This paper shows that this range correlation value (RCV) could well exceed the known correlation limit of 100% due to the unexpected VSWR reflection, multipath, or space or hardware delay, as mentioned above.