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This table contains examples of downlink frequency assignments; Satellite Frequency Band Terra: 8212.5 MHz: 8175-8215 MHz METEOROLOGICAL-SATELLITE SERVICE Earth exploration-satellite service Aqua: 8160 MHz: 8025-8175 MHz: Earth exploration-satellite service NOAA 17,18 1707 MHz 1700-1710 MHz: Meteorological-satellite service: ERS-2 (High rate ...
Most transponders operate on a bent pipe (i.e., u-bend) principle, sending back to Earth what goes into the conduit with only amplification and a shift from uplink to downlink frequency. However, some modern satellites use on-board processing, where the signal is demodulated, decoded, re-encoded and modulated aboard the satellite.
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 ...
The variety of frequencies used, as well as the desire to have tightly focused downlinks for security, require a range of antennas, seen in the picture: 2 SHF downlink phased arrays; 2 satellite-to-satellite crosslinks; 2 uplink/downlink nulling antennas; 1 uplink EHF phased array; 6 uplink/downlink gimbaled dish antenna
Nearly all C-band communication satellites use the band of frequencies from 3.7 to 4.2 GHz for their downlinks, and the band of frequencies from 5.925 to 6.425 GHz for their uplinks. Note that by using the band from 3.7 to 4.0 GHz, this C band overlaps somewhat with the IEEE S band for radars.
Whereas satellite contribution links may be provided using transmission in K u band (or even C band) frequencies, it is increasingly common to use the higher frequency Ka-band uplink and downlink for the contribution feed, as that band is relatively unused.
Due to the high orbital speed of the amateur satellites, the uplink and downlink frequencies will vary during the course of a satellite pass. This phenomenon is known as the Doppler effect . While the satellite is moving towards the ground station, the downlink frequency will appear to be higher than normal.
Uplink facilities transmit the signal to the satellite over a narrow beam of microwaves, typically in the C-band frequency range due to its resistance to rain fade. [20] Uplink satellite dishes are very large, often as much as 9 to 12 metres (30 to 40 feet) in diameter [ 20 ] to achieve accurate aiming and increased signal strength at the ...