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Doppler tracking.The Doppler effect allows the measurement of the distance between a transmitter from space and a receiver on the ground by observing how the frequency received from the transmitter changes as it approaches the transmitter, is overhead, and moves away.
Doppler shift of the direct path can be estimated by the following formula: [22], = where is the speed of the mobile station, is the wavelength of the carrier, is the elevation angle of the satellite and is the driving direction with respect to the satellite. The additional Doppler shift due to the satellite moving can be described as ...
Doppler positioning involves recording the Doppler shift of a radio signal of stable frequency emitted from a satellite as the satellite approaches and recedes from the observer. The observed frequency depends on the radial velocity of the satellite relative to the observer, which is constrained by orbital mechanics. If the observer knows the ...
The frequency differences observed are due to different Doppler shift resulting from relative satellite motion and differences in the translation frequencies of the two satellite channels. Channel translation frequencies and downlink Doppler shift and delay can be calibrated out of the measurements by observing transmitters of known location ...
Differenced one-way doppler (DOWD) is a method of spacecraft navigation. [1] The process uses two TDRSS communications relay satellites receiving the same telemetry broadcast from a satellite. The Doppler shifts experienced by both TDRS satellites can be processed using ground equipment to generate trajectory estimates without the need for ...
Doppler radio direction finding, also known as Doppler DF, is a radio direction-finding method that generates accurate bearing information with minimal electronics. It is best suited to applications in VHF and UHF frequencies and takes only a short time to indicate a direction. This makes it suitable for measuring the location of the vast ...
Doppler spectrum. Deliberately no units given (but could be dBu and MHz for example). This is an issue only with a particular type of system; the pulse-Doppler radar, which uses the Doppler effect to resolve velocity from the apparent change in frequency caused by targets that have net radial velocities compared to the radar device. Examination ...
For small angles, an ISAR image is the 2-dimensional Fourier transform of the received signal as a function of frequency and target aspect angle. If the target is rotated through large angles, the Doppler frequency history of a scatterer becomes non-linear, following a sine wave trajectory. This Doppler history can not be processed directly by ...