Episode: 136
Title: HPR0136: Intercepting Satellite Transmissions
Source: https://hub.hackerpublicradio.org/ccdn.php?filename=/eps/hpr0136/hpr0136.mp3
Transcribed: 2025-10-07 12:16:14

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Hello, I'm Drakenews. It is 2 in the morning and you are listening to Hacker Public Radio.
We've got to keep our voices down because we're outside in the park and are rather populated
housing community and they have security and I'm standing out here with a laptop
and large pieces of radio equipment and stuff so we need to be quiet so do not attract attention.
We're going to be intercepting photos from satellites so doesn't it sound cool?
The NOAA is 17, it's about to pass over, it's two something, it should be here in a couple minutes.
And what that is is that's a lower orbiting weather satellite that constantly transmits photos down kind of what you see on the
news and we're going to go ahead and snag the pictures as best we can from that.
Now NOAA is the NOAA, is the National Oceanic and atmosphere administration.
I think it's a US only, a pretty certain and they have two satellites in orbit, two types rather.
Geo stationery, which is what you see on the news, the large ones that can update the fast and digital
and kind of the older ones which are the polar orbiting ones and they're called Leo's low earth orbiting satellites.
So there are three active Leo's and this one is the NOAA 17.
I can also grab the NOAA 15 and the NOAA 18 but at the NOAA 17 it's coming up.
These satellites operate on 137 megahertz and transmit with about five watts in about 800 to 3000 kilometers in the air.
Five watts doesn't carry very far.
The biggest problem we have though with taking up on these satellites is that they're using 300 kilohertz bandwidth because they transmit a lot of information.
And I'm using a radio scanner that cannot pick up a bandwidth that wide so we're not getting as much information.
And that's going to be a problem that most people are going to have when they try to do this.
So what you're going to do is you're going to need a radio receiver.
I'm using a scanner from RadioShack.
It's a piece of crap from like the 80s but it does a great job because you don't need a lot of receiving power.
You just need a decent thing.
You can actually take a cheap FM radio just like a standard radio and just tune it up because 100 to 7 megahertz isn't that far from the typical FM spectrum.
It's like 100 in some megahertz.
You need to kind of have a lot of technical knowledge that go in modified FM radio.
But if you're really cheap and you have a lot of time, you can find instructions.
It's not that hard.
You also need an antenna.
No, you know, the organization actually uses quadrifillo helix antennas, which is considered like, you know, the holy grail of antennas for this purpose.
But I'm using a disco antenna right now that was made for like 800 megahertz but it was made for only made so it's going to work just fine for this.
I've also heard that a linen wand, a linen plan, how are you say it?
The antenna works great and it was easy to make, I've heard.
And I was using a dieboard antenna early just to play around.
And that barely worked in the style I just directly above me.
So I would recommend, you know, you make the antenna.
That's just these specifications.
But I'm going to use this one.
I think it's going to work.
You also need a computer to do the actual image processing.
I'm using a laptop right now.
It's, you know, it's like a dual-core machine.
It's so overpowered for doing this.
But if you have like an old, like a penny immuno machine lying around,
you can set up a dedicated station because you can do this with Linux Windows or I think you can back now.
And, you know, just have a station that sits there all day and receives your own satellite images, if you really didn't do the idea.
You also need a good sound card because what we're doing is we're taking the audio from the receiver, which in my case is a scanner.
And processing that and creating an image from it.
So I'd recommend getting a USB sound card because it wins external and away from all the computer parts.
There's a lot less electronic noise and you want to keep noise up because noise is going directly relate to it for an image in this case.
Actually, though, the USB sound card that I have has more noise on it than the sound card in my laptop.
So I'm just using the one built into my laptop.
You also need a piece of software.
There's tons of software that we're doing because we do this like a decade ago.
It's very popular. It's not as popular now, but it's all the salads are digital.
But we can still pick up these ones.
I'm using what's called APT decoder and APT stands for automatic picture transmission, which is what the lowest satellites prefer to when they're sending images down.
These runs on Windows.
And I'm going to go ahead and open that.
Just as a moment, I need to set up my scanner.
Because we're picking up on the node 17, we're going to set this to the correct frequency.
So go ahead and monitor.
Now, if you're using a radio scanner, you want to make sure that you turn this grouch all the way down to off.
So that you just get a whole bunch of white noise coming out.
Because you don't want to, the signal's going to be very weak all the time.
You don't want the scanner clipping that off or anything.
I'm going to go ahead and bring up a APT decoder.
Now, there's some software things that you need to do because you want to get it set up just right.
Now, I'm not going to include all the software setup that you need to do because no one's going to listen to this and take notes.
So I whisper, you know, software details.
But if you want to go to my blog at drakenewis.com, you just find the post on satellite imaging.
It's probably the most recent one depending on when you listen to this.
I'll have all these software instructions in there.
It's not that many, but you just want to get set up with your location and make it out of process and out of recording things.
Okay.
I also have this new voice here.
So you can actually hear what's going on.
Let's go ahead and get an update in just a couple of moments.
All right. So what's going to happen to satellite is going to be coming into range.
That's been very fainted first.
And then it's going to even here like this take talk or the siren tone depending on where you are.
And the computer, because it was my location, it knows where the satellite is.
It's going to automatically start recording the tones.
It's not that, yeah.
And because my configuration is going to also automatically start processing the image.
I'm going to edit this part a lot because the pen has this going to be like eight minutes and you don't want to submit eight minutes of siren noises.
But here we go.
Now recording from 017.
All right.
So what it just did is it opened the screen.
I can now see lines going across like scan lines as it decodes the information.
It's very grainy right now.
It's going to sharpen up in a little bit.
So it's pretty loud.
I'm going to jump straight to that part.
I'm going to raise the volume so that you can hear what the satellite sounds like.
Okay. This noise.
This is the noise of the actual satellite out of your room talking over.
But when you're really getting a good image, you're going to be hearing this take talk noise.
Very distinctive take talk noise.
Otherwise, we're just going to hear this kind of tracking noise.
Say something.
Actually, if you don't have the ability to do this, go to my website and look at the waveforms that I have.
But it makes kind of a cool pattern just because all the signals and you can see the different noise and things.
It's kind of cool.
017.
Now we're sitting.
Has to meet a boss of signal in two minutes in 49 seconds.
All right.
The satellite's moving away and we're kind of losing the signal now.
Now we got a pretty decent picture.
I'm going to go ahead and put this up on my website.
What you see in the image is mostly black and green.
You know, it starts getting greener and brighter and brighter.
And you start seeing an image with lines going through.
And you get pretty clear image for a while.
And then it drops away.
It's more noise picks up.
So I'm not using the most ideal antenna.
But also if you go into the settings and I'll have notes on this.
You can do things like look at the space craft type and look at the path analyzer and path analyzer.
It's going to connect the asthma and elevation to the level of noise that you have.
And you can see kind of this cool graph.
I love graphs.
How much noise you're getting when you can tune your antenna and stuff.
You want to make it a really great hobby in this.
There's plenty to do here for relatively low cost.
As long as you want to dedicate a tiny boat in your equipment and stuff.
So do you have any questions or comments?
Especially contact me if you have a like if you've gotten your own pictures.
Because I just love kind of geeking out and walking this pictures and stuff.
So if you manage to do this on your own.
Some of your results will think I'll post them online if you want to.
But I'm breaking news at gmail.com or my blog has comments that no one ever uses.
Because I never check them.
And all right.
It's fate to the.
Yeah.
That's real.
Thank you for listening to H.P.R.
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