hpr-knowledge-base/hpr_transcripts/hpr2189.txt

Episode: 2189
Title: HPR2189: Working Amateur Radio Satellites
Source: https://hub.hackerpublicradio.org/ccdn.php?filename=/eps/hpr2189/hpr2189.mp3
Transcribed: 2025-10-18 15:30:15

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This in HPR episode 2,189 entitled Working Amateur Radio Satellite.
It is hosted by Christopher M. Hobb and in about 32 minutes long and Karima Clean Flag.
The summary is a brief overview on how to work your first satellite.
This episode of HPR is brought to you by AnanasThost.com.
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Hello HPR. You're going to have to bear with me on this episode. My rockbox seems to be having all sorts of trouble.
Got a nice squeaky chair here and I'm working on a cold but I'll be darned if I'm not going to get this episode done.
It's been a while since I've finished an episode. We're going to do another one.
My name is Christopher Hobb and today I'm going to talk about working amateur radio satellites.
I'm an amateur radio operator. My call sign is KD5RYO.
I've been a ham since about 2003. I did have a break between 2013 and 2016.
We had a baby and I just kind of quit working the radio and my license lapsed.
But here recently my son had asked me about satellites because he was learning about the International Space Station
and so I got my amateur radio license again so I could show him how the satellites work.
Unfortunately being a six-year-old he has very fleeting interest and he no longer cares too much about the satellites but the bug hit me.
So here I am working on satellites again.
So you can find a little more information about me and my contact information at manner.space slash tilde cm Hobbs, HLBBS, or Hobbsc at stf-us.org.
I hope to have some satellite info up there soon but for the time being it's just a bunch of rambling about me.
So let's jump right into it.
A little introduction about satellites here. First I want to note that I am not an expert at this at all and I am still constantly learning.
I'm called an amateur radio operator for a reason. Not a professional operator, I'm an amateur.
So if you have additions or corrections for my information here I would love to hear it.
If I can do something better let me know. Or if you just want to talk about amateur radio in general I would love to hone my craft with other people so please let me know.
So as far as satellites are concerned as far as I can tell there are dozens of these low earth orbit satellites that happen to have amateur radio repeaters on them.
And then there's also the International Space Station.
The ISS is a topic for a different show entirely though because it happens to carry all kinds of radio equipment and there is often astronauts on board who also have radio equipment.
The focus of this episode is going to be on the actual satellites particularly those that were placed up by AMSAT the American satellite company.
American amateur radio satellite company and something to that effect.
So many years ago 13 years ago or so when I first started trying to work these things they used to call them Oscars which stands for orbital satellite carrying amateur radio.
Now I don't really see that name too often anymore and I don't know what happened to those my my thought is maybe Oscar was the name of a particular chassis.
I know there's a lot of discussion about Fox chassis for satellites now and fun cubes or if the name just fell out of favor I'm not really sure.
But even though they're amateur satellites one of the cool things about this is you don't have to have an amateur radio license to receive the signals from these satellites if you have handheld or any other radio that will receive two meter or 70 centimeter you can go ahead and pick these up.
The other cool thing about that though is that the only license you need in order to transmit on this is the amateur radio technician class license which is great because it is the lowest license class and it's the easiest to obtain you have to answer a 35 question test and that's in the United States anyway and that's about it.
It's the license that I have and I highly recommend anybody who's interested in radio at all despite the bullet and go get your amateur radio ticket and a whole world of tinkering will be opened up to you.
So the gear necessary for this when I first started thinking about satellites I thought I was going to have to build a separate building and have a huge satellite dish and all kinds of stuff to receive these things.
And really all you need is a handheld radio with a little bit better antenna than what comes with it.
I mean there are stations that use automatic rotor control and have giant beam antennas and put out a lot of power but that's not necessary.
You can get by with just a handheld and that's sort of the discussion of my show today I'll talk about how I work these satellites with just a handheld.
So generally how does it work so I can hear people's brains turning and they say well don't don't radio signals you know bounce around and my cousin used a CV radio and he talked on the skip halfway across the country.
Yeah so high frequency or HF radio can can bounce off of what's called the ionosphere which is a layer around there and that's yet another topic for yet another episode but high frequency signals can be bounced off of the ionosphere.
However the frequencies used for amateur radio satellites are commonly used in terrestrial applications as well their VHF and UHF very high frequency and ultra high frequency.
These radio signals have the ability to pass through the ionosphere so they can go straight up to the satellite and straight back down.
And that's what you're doing they're the satellites carry a repeater on them much like a terrestrial repeater on earth the only difference is these repeaters are whizzing across the sky at seven kilometers per second.
So they require a little more effort to talk to than the repeaters on earth.
And naturally there's a lot of contests and awards for working satellites and I'm just barely scratching the surface on that amset provides several amset UK provides a few.
There's the Harris organization and in various other organizations for working satellites.
So little information about my kit what I'm using is a Yasu FT60R that's the American version of the Yasu FT60 handheld.
It's a dual band transceiver does two meter and four 40 or two meter and 70 centimeters.
And I normally just use mine for talking on local repeaters here and picking up aircraft bands and that sort of thing some scanning.
I use a comment SMA24 whip antenna which is a small upgrade over the rubber duckie antenna that came with my Yasu.
I've never actually used the rubber duckie antenna that came with this radio.
But I imagine it could at least receive satellite signal with some degree of success.
I use a Yasu C44 audio cable. Now this is usually used to hook up a TNC or a terminal node controller for digital radio or I'm sorry for packet operation or digital modes.
But I use it to plug headphones into my radio and I use a mono-tisterio adapter between that and my Sennheiser HD380 Pro headphones.
And those are big cans.
My hearing is going as I get older from too many loud screaming devil music shows.
And so I like to use big headphones that I can turn up to a comfortable level and block out the noise around me.
Now I'm not set up for recording an actual conversation.
I will include a terrible video in the show notes if you want to go hear what it sounds like when you receive these signals.
But the problem is I've tried to do this with my video camera.
Number one, I don't have an audio recorder other than my rock box here and the rock box doesn't have a microphone input.
And then not only do I have the trouble of holding paper and pin and antennas and radios and cables and so on and so forth,
but adding recording equipment to that mix, it's just too much for me to juggle all at once.
I wanted to have my son out there working with me, but since he's lost interest, I'm having trouble recording it.
I am working on equipment to be able to do that in the future, but at the moment it's just not going to happen.
Now, how I find the satellites and track them is I use a piece of software called G predict, which is available for GNU Linux.
It's also available.
I believe there's a Windows build and there's definitely a Mac build.
I use it on Debian. It's a wonderful piece of software and it is free software, so I highly recommend that one.
I use a compass with an azimuth dial on it.
I use a head lamp because often I'm working these things at night.
The satellite that I've paid the most attention to tends to pass over my location at about 2100 central time,
which I guess is probably what?
0300 UTC, something like that.
And then I have a pad of paper rubber banded to my arm and a pencil stuck in there so I can try to make quick notes.
So some other useful stuff that I'm considering that would be really nice to have is a number one, a real antenna.
So this whip is kind of unwieldy. It just flops around and it's not directional at all.
You know, it transmits out all directions and it's just really inefficient.
It's not very high gain.
Yes, I can get out there. Yes, I can work the bird, but it is a whole lot of effort to make that happen.
So I've been working on building a directional yaggy, well, all yaggies are directional, but I've been working on building a yaggy antenna out of all things.
Coat hangers in a piece of wood.
The problem is the piece of wood I have is not quite long enough, so I need to go find a much longer piece of wood.
And I advocate trying to build your antennas before buying them, but if you'd like to buy them, there are some great satellite antennas.
And they cost anywhere between, I don't know, $150 bucks to $400 for the handheld models.
And then you could probably buy a new car for some of the automatic control ones.
I haven't looked into that realm because it seems quite expensive.
I could use a hand mic. A hand mic would make things much easier, especially if my antenna was detached.
I really need to put together a recording setup, and I'm still thinking through that.
I need to get another waterproof paper pad. It's been cold and wet lately.
And my right in the rain paper has been all used up, so I need to get another one of those.
And it sure would be useful to have extra hands. I need to have a buddy to help me with this, but it can be done on your own.
So a little bit about my experience with this.
Years ago, I used to try and track and listen to the International Space Station.
And that all went well, made some contact, and got to do some listening.
But I gave up on it because I couldn't find a lot of resources for actually figuring out where satellites were.
I don't know if that was my inability to search properly, or if the software just didn't exist.
But no, it's much, much easier.
In probably three short weeks, I've finally made a contact, and I've been able to track multiple satellites.
The main one I've focused on lately is SO50. That's SO-50.
And I managed to hit it and made my first contact last Saturday, December 3rd, with K-O-4-M-A.
That's Kilo Oscar IV, Mike Alpha, who happens to be the Vice President of Operations and the Director of AMSAT.
So that was a very fitting first contact for me to make. I was super excited when I heard that.
In fact, I was so excited when I made the contact that I completely dropped protocol and floundered on the air.
And then after we finished up the contact, I dropped on my gear and rushed inside to log the contact.
So that was a really exciting one.
I've been tracking and trying to receive AO73, which is also known as FunQ1.
I think I have the wrong downlink frequency for that. I've never actually been able to hear it, but I've not found any reports that it's transmitter is dead.
So I'm not sure what's going on there.
The third satellite that I've tried to work is LILAC-SAT-2, which is a Chinese satellite, and it carries telemetry data.
Now, the interesting thing about LILAC-SAT-2 is they provide a GNU Linux live CD that's got everything you need, minus the radio, to receive and decode their telemetry data.
Now, I've not used this ISO, but I did manage to pick up its data transmissions with my YASU.
And at some point in the future, I will try to plug my YASU into my computer and either use their live CD or use something like FL digi to decode their signals.
Now, here's a cautionary tale.
When you start to pick a satellite that you think you want to work, be sure and search the internet and make sure that it still transmits and receives.
For many days, when I started this, I tried to pick up AO51.
That was before I realized that it's been inactive for some time now.
It used to be a very popular satellite for beginners, and a lot of the amateur radio satellite guides listed as a useful satellite to try to work.
Well, it's hard to work a bird that's dead.
And I was completely unable to pick it up, and then a few days later, I realized the error of my ways and switched my focus over to SO50.
So let's get to the real action here.
So how do you do it?
How do you take your little handheld radio and bounce a signal off of a satellite and have someone halfway across the country hear it?
Or maybe even in another country?
Well, the first thing you need to do is get a radio that will transmit and receive on different frequencies and bands.
So my FT60 can transmit on one band and receive on another, and there's a ton of other handhelds that will do that.
But if you don't have a radio that will do that, you can use two radios.
You can receive with one radio and transmit with another, but this brings up the issue of having more hands.
So you would need a buddy for that one.
So you need to be able to find these satellites.
Now, satellite data, positioning data, is encoded in what we call capillary and elements, or caps for short.
Now, I'm not going to pretend to be an expert on these things.
I know very little about each of the data points in the capillary and elements.
All I know is that I feed the capillary and elements into G-Predict, and it tells me where it thinks the satellite will be at any given time with a great deal of accuracy.
If you're using G-Predict, it uses what are called TLA file, TLE files, which have capillary and elements in them.
You can update those TLA files over the network quite easily.
You can have G-Predict do it automatically, or you can manually upload your own TLA files into G-Predict.
You will provide an AmSat list of TLA frequencies that has some different satellites than what the default network download, which I believe is from Celestrac, and G-Predict has available.
So you need to keep G-Predict updated.
I like to update it every 48 hours or so, and you can have it update automatically if you like.
If you don't keep it updated, there can be some drift in the satellites, or if the satellites got bumped by something, or if they're spinning, or any number of things can just slightly alter their orbit, and then your numbers will be off, and that's a really frustrating situation to be in.
So once you've got the TLA's loaded up, and you have a few satellites marked off in G-Predict that you want to use, and you've got G-Predict setup like you like it,
watch the schedule for a few days. Don't just jump right into this. Watch the satellites fly overhead on your lunch break, or in the evening before you go to bed.
Make note of a few things, and get familiar with the interface. The three big things you're going to need to know, the three big points of data, is first what we call the AOS, or the acquisition of signal. You need to know the azimuth of that.
That's when the satellite is coming up over the horizon. Then you need to know the azimuth for the maximum elevation of the satellite, which is when the satellite will be at its peak.
The last thing you need to know is the LOS, or the loss of signal, the azimuth for that, and that's when it's going to be right at the horizon coming back over.
So start digging through the schedules for the satellites that you want to try to work, and start making note of those three data points.
It's good practice, and you can start to get a feel for when the satellites might be overhead.
You may also want to spend a few days simply receiving instead of transmitting, but either way, you definitely want to spend a few days just getting a feel for what the birds are doing.
So now that you know what the schedule is like, you're going to need to program your radio, and one big thing that's different than terrestrial repeaters, is you're going to need to set several memory channels as opposed to just one.
You know, with a terrestrial repeater, it has an input and an output, an appeal tone to activate it, but the repeater is not moving around.
The satellite repeaters are flying over you at breakneck speeds, so you have to compensate for Doppler shift.
Just like if a train passes you blowing its horn, when it's approaching, the sound of the horn will be a higher pitch than it actually is, and as it passes you the pitch will decrease.
This also applies to radio signals, sorry, radio frequencies.
So as the satellite is coming up over the horizon, it will be on a higher frequency than its actual downlink frequency due to that Doppler shift, and as it passes back over the horizon at the end of its arc, it will be at a lower frequency.
So you need to set several frequencies to compensate for that in your memories.
So an example with SO50, I like to set a middle channel, usually 50, so that I know it's SO50 if I don't want to program a name into it, to transmit on 145.840, and note that the transmit frequency does not change, because you're not moving the satellite is.
So I set that middle channel to receive on 436-795, which is the actual downlink frequency of SO50.
So then what I do is I set 3 to 4 channels to the left of middle, where I increase the receive frequency by about 5 kilohertz.
So that's usually channels say 49, 48, 47, maybe 46.
And so 49 instead of being 436-795 would end up being like 436-780 and then 436-785, and so on.
And then I set 3 to 4 channels after the middle frequency, where I decrease the receiving frequency by about 5 kilohertz.
So you're looking at channels like 51 through 54, maybe, and it starts going from 436-795, which is the middle to 436-780.
Oh, I'm sorry.
Well, I've watched that.
Anyway, you guys get the idea.
So as the satellite comes overhead, you have a higher frequency as it goes back over, you have a lower frequency, so it would be 790, and then 785, so on and so forth.
And so again, all of this is to compensate for the Doppler Ship.
There are people who have programmed out the frequency charts for Doppler Ship.
You can go look those up, and I apologize for watching the example, but hopefully it was clear enough.
Another thing I like to do is add an additional middle channel with a PL tone to activate the repeaters.
So that's a major difference between terrestrial repeaters and satellite repeaters is that a terrestrial repeater usually has a single tone to activate it because it's on all the time.
But in order to save power, sometimes the satellite will have a power saving mode, and it will not repeat any signals until it's woken up.
And that's with a separate PL tone than the normal input tone.
So once your radio is all programmed up, you need to pick a day when your target satellite will be at a maximum elevation of about 70 degrees or more.
Now I know that's very high, and you can work much shorter angles, even with a handheld, you can work almost as low as 10 degrees, but it'll be frustrating.
So try to aim for 70 degrees or higher for your first runs so you can get comfortable with how to point the antenna when trying to receive the satellite.
So half an hour prior to the satellites pass, go get your compass out, and you need to shoot the azimuth of the acquisition of signal, the maximum elevation, and the loss of signal.
Now how to shoot an azimuth in fine directions and stuff is also probably for another episode, but the basic rundown is this.
You take the number of the azimuth for the AOS, you move your azimuth wheel on your compass to point to that particular number, and then you find north, and then once you find north, you should be looking right at the point at which the satellite will come over the horizon.
Make note of a landmark there, repeat this process for the maximum elevation, make note of a landmark, repeat this process for the loss of signal, and note a landmark.
With those landmarks you should be able to see a general arc for where the satellite is going to be, and you're going to need to physically move your body and your radio, or at least your antenna, to follow this arc as it comes over, as the satellite flies overhead.
So once you know what the pass is going to look like, then you're going to go outside when the pass starts, and point your antenna to where the acquisition of signal will be.
Now, you don't want your antenna pointing straight up and down, you want to try to put it perpendicular to where the satellite will be, and that will take some finesse, but usually if it's coming up at zero degrees and it's going to be a ten or something, you're going to be pointing your antenna almost directly at the ground.
And you just kind of want to move your antenna up and down and around, and note that you want to be on the, furthest to the left of the Doppler Shift possible in your memory channels, so that you can compensate for that.
Now, as the satellite starts to pass overhead, you'll hear some quieting, and you might even hear voices.
And when you hear that, you want to tune your VFO or tune your memory selection so that you decrease the Doppler Shift as it goes, so you decrease your frequencies as it potentially comes overhead.
Now, you don't want to spend a lot of time flipping through those because you can lose the signal if you're not careful.
So I find that before it hits its peak, I like to stay on those higher frequencies until I hear somebody talking, and then I just tune it to adjust the tone of their voice, and then as it goes to starts to fall, I like to use those lower frequencies and tune.
But the big thing is you want to make sure that antenna is pointing the right direction.
So to recap, step outside, point the antenna the direction of the acquisition of signal, and make sure it's perpendicular to that elevation, and start moving your antenna up and down on your highest frequency program until you start to hear some noise.
If you don't hear any noise, you want to kind of move and follow the arc, maybe increase, I'm sorry, decrease the frequency a little bit, and just keep doing that over and over and over, watching the time to see if you can pick this thing up.
Now, a big thing to note is you need to run with your squelch fully open because usually there's not going to be a strong enough signal to activate, rather deactivate your squelch.
So that's a big kicker. Make sure your squelch is fully open.
Once you hear quieting, or you hear a voice, you know you have that signal.
You should at that point have an idea for how you need to move your body and move the antenna to compensate for this.
Once you have that quieting, or you hear voices, don't turn your VFO or your memory knob unless people's voices start sounding weird.
Once you have that quieting, and once you have that voice, you're going to be able to simply move your body and move your antenna with the arc until the satellite falls out of your, until you can no longer receive a satellite from the satellite as it falls over the horizon.
So that's the nice part. It takes a little effort finding the signal, but once you've found the signal, you don't have to do much except for make tiny adjustments to your hand and body and antenna to keep the signal strong.
Once you hear people talking, or once you hear quieting, you can activate the, you can activate the repeater on the satellite.
You want to key up, and you want to give three pieces of information. You want to give your call sign, your grid locator, and your handheld.
So in my case, when I'm in my backyard, I call Kilo Delta V, Romeo Yankee Oster, Echo Mike 26 handheld. Now, KD5RYO is my call sign, EM26 is my grid locator, and handheld is my mode of operation.
Sometimes people will come back to you and sometimes they won't. If they don't, wait for another break in the conversation, and give your call again.
And you just keep doing that until you make a contact, and then from there, the contact is much like any other hand radio contact. You might exchange niceties, or you might exchange weather information, or whatever, but it's usually brief because there's just a small window of time to talk.
And with some practice, you'll get the hang of it. Now, I hope that my description was useful. That's a lot to take in, and it really helps to see it happen.
There are a lot of videos on the internet for how to do this, and there are great explanations on paper for how to do this.
I'll provide a few resources here, so these will all be in the show notes, but I'll run through them quickly. There's the Amset Status page at amsetnet.org slash status.
And if you do happen to receive these satellites at all, especially if you happen to make a contact with them, please go log that on the Amset Status page.
That page is only updated by people who have gone out and received the signal, and it's a highly useful tool for me and other amateurs for us to know whether or not number one, the repeater on that particular satellite is active, and number two if anybody's heard any activity on it.
So please update that page if you see it. If you hear one of those birds, rather. Now, once you are on that page, you'll notice that several of the satellites' names are actually links, and they provide information to the satellites for things like transmit and receive frequencies, Doppler, Shift, and so on and so forth.
Amset also has an intro and tips page, which I'll link in the show notes. There's also Amset UK for people across the pond, which is at amset-uk.org.
WorkSat.com is a very useful resource, and their intro PDF is super nice. The problem with WorkSat is it's really scattered. It's not necessarily designed so much as it's information overload.
So if you go to WorkSat, take a look at their introductory PDF, and then once you start working some satellites, you can decode more of their information.
eham.net has a satellite forum rather, but it's not very useful. People don't talk there often. I find that I use it for new satellite announcements and announcements of trouble with satellites, and also for occasionally international space station schedules.
The hash hash ham radio channel on free note is very useful, and the people are generally friendly. Amset does provide capillary and elements, and I will provide a link to those files, so it's kept rather.
And then two mailing lists that I find very useful are the Amset BB, which is the General Discussion Amset List, and the Amset ANS, and the Amset News Service, which is a weekly publication with satellite information.
So once again, I hope that that wasn't too confusing. If you have any questions, feel free to reach out, and I hope that you try to go out and work satellites, and if you are not an amateur radio operator, once again, I would encourage you to go get your ticket.
It's relatively easy to get the technician class, and there is so much that you can do with it. So with that, I'll go ahead and say 73. Thank you for listening. I can public radio. Until next time.
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