Working The Satellites
Over the last three articles, we’ve taken a look at the types of satellites, how to track them and what frequencies to use, and finally the minimum equipment required. In this part, we’ll get to accessing an FM satellite and working some stations.
If you’ve not already listened to a couple of passes before transmitting, can I recommend that you do so? It’s useful, if no other reason than to understand the adjustment required for Doppler shift.
Choose Your Satellite
For the purposes of this, we’ll use the ISS as our example satellite. It can be useful to make a note of the satellite and its frequencies in a notebook as an aide-memoire.
Ideally you’ll need to program your radio with the relevant frequencies and store them into channels (refer to our guide to programming the Baofeng handheld radio, which also works for the Retevis RT95 too).
Note down the times of the pass (AOS, maximum elevation, LOS) and where it will pass through the horizon. If you are using the Satellite Tracker app on iPhone, you’ll see a green dot appear when the satellite reaches AOS.
In our example, the ISS has reached AOS and is due West of our position. Point the aerial in that direction, set the receive frequency to 437.810MHz and listen for activity! Depending on your location, it may take a minute or so for the satellite to clear obstacles obstructing the signal path, but the ISS puts out a very strong signal so you’ll definitely know when you hear it.
Wait until you hear the repeater in action before transmitting.
Duplex Operation
It is strongly encouraged that satellite operators full duplex operation, so that you can monitor your own transmission. You’ll definitely need to do this for operating the linear satellites, and it is good practice to do so with the FM satellites too.
However (and many will vehemently disagree with me here), if you are just starting out and want to see if satellites are for you, you can get away with a single [non-duplex] radio. If you are going to explore the world of satellites in a more serious manner, then please, please get a duplex set up so that you can monitor your own transmissions.
Transmitting
You must consider that an FM satellite pass is likely to be around 12 minutes long, at the most. There are stations throughout the footprint of the satellite (essentially across all of Europe) that want to make contact. It is important that operations are efficient to make the most of the opportunity.
There is no need to call “CQ” on an FM satellite (you wouldn’t do it through a ground-based repeater). Either listen for another station to call and make contact direct with them, giving your callsign and locator, or just call with your callsign only.
An example of a ‘general’ call that I would put out over an FM satellite is just…
“GOLF SEVEN BRAVO ECHO HOTEL PORTABLE”
If I heard M0VVA calling and wanted to respond, my call back would be…
“MIKE ZERO VICTOR VICTOR ALPHA, GOLF SEVEN BRAVO ECHO HOTEL PORTABLE, ITALY OSCAR EIGHT ZERO, ROGER?”
Hopefully M0VVA would confirm my call and provide me with their locator.
Please do not…
- Call “CQ satellite, CQ satellite, CQ satellite. This is <callsign>, <callsign>, <callsign>, listening in“. It takes too long and you’re hogging the repeater, preventing others from making contacts.
- Transmit silent carriers.
- Key up and whistle (a la CB-radio circa 1981).
- Enter into lengthy conversations with another station.
Contacts on the FM satellites are quick, which gives everyone a chance.
Summary
In this article, we had a quick look at how to work the FM satellites efficiently, to give everyone a chance to make contacts. Satellites such as the ISS can be very busy and congested – to the point of being unworkable – especially at weekends. Choose your time carefully and be courteous.
In the next article we’ll take a quick look at how to make the most of satellite footprints.