Doppler Noise Research Articles

A THEORETICAL ANALYSIS OF A COMPRESSED-TIME CORRELATOR FOR SIGNAL DETECTION

The theoretical problems of a compressed-time correlator are investigated from the viewpoint of signal detection. Through discussion of the LMF arid PR signals, some useful conclusions and basic formulas concerning the output signal, spectrum structure, Doppler filter set-up, noise background, SNE gain and signal envelope smoothing are obtained. As a consequence, it has been possible to design an improved sound pulse-compression receiver.

An FM-CW Radar for Simultaneous Three-Dimensional Velocity and Altitude Measurement

An FM-CW radar is described which simultaneously furnishes three-dimensional velocity and absolute altitude information. The velocity is measured by means of a low-frequency FM-CW Doppler technique, and the altitude information by means of phase comparison on one of the sidebands of the received spectrum. The optimum radar parameters required for the two functions are completely compatible. Use of the first-order sideband permits operation of the system down to zero feet altitude; use of the second order to very nearly zero feet. Offset reference frequency techniques and narrow-band leakage elimination techniques permit system operation through zero speed and to negative speeds. Contrary to that of conventional FM-CW altimeters, the altitude measurement technique is unaffected by amplitude noise and by frequency (Doppler) noise due to vehicle motion. The radar technique is particularly applicable to helicopters, VTOL aircraft, lunar landing vehicles and possibly also to satellite rendezvous. Actual flight test results have demonstrated the feasibility of the radar technique.

An FM-CW Radar for Simultaneous Three-Dimensional Velocity and Altitude Measurement

An FM-CW radar is described which simultaneously furnishes three-dimensional velocity and absolute altitude information. The velocity is measured by means of a low frequency FM-CW Doppler technique and the altitude information by means of phase comparison on one of the sidebands of the received spectrum. The optimum radar parameters required for the two functions are completely compatible. Use of the first order sideband permits operation of the system down to zero feet altitude. Offset reference frequency techniques and narrow band leakage elimination techniques permit system operation through zero speed and to negative speeds. Contrary to conventional FM-CW altimeters, the altitude measurement technique is unaffected by amplitude noise and by frequency (Doppler) noise due to vehicle motion. The radar technique is particularly applicable to helicopters, VTOL aircraft and lunar landing vehicles, and possibly also to satellite rendezvous. Actual flight test results have demonstrated the feasibility of the radar technique.

Relation between Doppler Noise and Navigation Accuracy

Relation between Doppler Noise and Navigation Accuracy