If you cannot roof-mount your antenna, good results are still possible so long as there are no obstructions nearby. Ideally, it should be the topmost structure on any antenna mast.
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If roof-mounted, make certain that no metal objects are likely to come between it and the satellites. The antenna should be positioned with a clear aspect to all horizons. There are two common solutions to this problem, the crossed dipole (or turnstile) and tuned specifically for the 137 MHz band. The signals from the NOAA weather satellites are transmitted with right-hand circular polarisation. This is not going to be an in-depth tutorial, just a quick outline to give you the general idea. I personally have not done this and still get good results. So that means we really have to continually adjust the frequency. Compensating doppler shift requires frequency tracking in narrow band receivers.
![geostationary weather satellites wxtoimg geostationary weather satellites wxtoimg](https://www.rtl-sdr.com/wp-content/uploads/2021/07/elektro_coverage_new.png)
The magnitude of doppler frequency shift is proportional to the closeness of the earth station with the ground track of the satellite. It affects both up-link and down link signals. The doppler shift effect is quite pronounced in Low Orbit satellites. The doppler shift effect is identical with the familiar change in pitch of a police car siren as it approaches then recedes from you - initially high pitched, becoming lower as the satellite firstly approaches the listener, flies overhead, then recedes again, this variation is added or subtracted to the signal thus widening its bandwidth. We must also talk a little about doppler shift.
#Geostationary weather satellites wxtoimg series
The United States has the NOAA series of polar orbiting meteorological satellites, presently NOAA 19 and NOAA 18 are primary spacecraft, NOAA 15 as secondary spacecraft, NOAA 16 and NOAA 17 NOAA have been decommissioned. Polar orbiting weather satellites offer a much better resolution than their geostationary counterparts due their closeness to the Earth.
![geostationary weather satellites wxtoimg geostationary weather satellites wxtoimg](https://www.nasa.gov/images/content/626979main_STILL-GOES-TORNADO.jpg)
Polar satellites are in sun-synchronous orbits, which means they are able to observe any place on Earth and will view every location twice each day with the same general lighting conditions due to the near-constant local solar time. Polar orbiting weather satellites circle the Earth at a typical altitude of 850 km (530 miles) in a north to south (or vice versa) path, passing over the poles in their continuous flight. I started decoding Noaa weather satellites images back in the 1980's and 90's but was put aside for a while and came back to it in June 2017. This is a another side of radio/space that I really enjoy.