playing with Satellites

[M0PWXParticipant]

Satellites are a fun activity with amateur Radio

the majority of amateur satellites are of low earth orbit (LEO) type and orbit the earth about every 90 minutes, you will get 2-4 passes a day on each satellite where you can use them for 7-20 minutes each pass depending on the maximum angle of elevation and the altitude of the satellite (e orbit, the larger the foot print and longer you would be able to work it)

because the satellites move across you have to track the satellites with your antenna, either handheld antenna (like an alaskan arrow yagi) or on a rotator that can track elevation as well as azimuth / heading

you don’t need a lot of power to work satellite, a 5w handheld like a Baofeng UV5r with a handheld dual band yagi will get you started, so for only about £100-£120 for a handheld and dual band yagi you can start

most of us start with SSTV from the ISS, or listening to the cross band repeater of the ISS, but there are many more satellites up there with amateur radio payloads on them

FM Satellites are the easier ones to work as they need less correction for doppler on the uplink/downlink frequency than the SSB / CW ones

Doppler shift is where the the frequency of something moving towards you increases and when it is moving away from you it decreases

with VHF satellites it is about +/-3Khz, UHF satellites it is about +/-9Khz

a useful source of information is Amsat, in particular the Amsat status page https://www.amsat.org/status/ this is a list of satellites with amateur voice repeaters / transponders and also reports of if they have been heard

they also do a program called SatPC32 which shows where the satellites are and can control radios with a CAT interface to adjust the TX / RX frequencies to track the doppler shift of the signals

websites that help tracking of satellites are https://www.n2yo.com/ and https://heavens-above.com/AmateurSats.aspx

if you want to have QSO’s on the satellites you will need a 2m/70cm antenna as they mostly work via cross band, uplink 2m with downlink on 70cm, or uplink 70cm with downlink 2m, there are a few 23cm satellites,

there is one geo-stationary amateur satellite QO-100, but this is up in the microwave bands at about 10ghz, but there are a number articles that show how to repurpose domestic satellite receivers to be able to recieve the signals

because QO-100 is geostationary it stays at the same point in the sky, this means once you setup your receiver dish you don’t need to move it, so you can listen any time of day, and because the altitude of Geostationary orbits are much higher than LEO orbits it covers about a 1/3 of the globe

have fun and enjoy your hobby

73

peter

M0PWX

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