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Comment by b1r6 | Hacker News Reader

I do indeed have my license. Only a Tech but even that level gets you access to the VHF/UHF birds.

Are you saying we shouldn't expect a military satellite to have some semblance of simple authentication?

It sounds like what they built was literally a simple repeater. If that's the case, they shouldn't have a problem with this "unauthorized use," because by design, there is no such thing.

(The preceding assumes the pirate is licensed to transmit in the 1.25m band that the article noted as the uplink.)

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Look, they're bent pipes because it's faster, cheaper and more scalable. If you do authentication, you need the satellite to process and validate each packet before repeating it. That means that suddenly you need a processor - a beefy one, to handle so many signals at once and understand the modulation, and you have a delay between receiving and sending. You also have new failure modes to worry about, new components that can fail, protocol lock-in, maintenance, etc.

Bent pipes are perfect. Not everything needs to be overengineered to hell. A handful of pirates aren't a big enough deal to boil the ocean with a DSP. And assuming that the signal is Manchester-coded, you can defeat the pirates in future models with a simple analog filter to remove their noise.

I now see what you're saying. I guess it's just funny that I could defeat military comms by simply leaving my mic open and bumping the dial to the right frequency...

It sounds like back in the day what I described above wasn't an issue.

You got it. When these birds were thought up, that was state of the art. Two years ago a dude I'm elmering told me he heard brazilians when he was tuning around with his sdr toy, so maybe they are still doing it today.

The uplink freqs are not any that are licensed for any amateur use, these flights are operating between 250-350 MHz.

Edit: look what I found http://mt-milcom.blogspot.com/p/alphabravocharlie-frequency-...

Ahhh very interesting! It's so funny to think I could hit military comms just by tuning up a bit on my modded rig... Not that I will, because that's dumb. Makes sense given the age of the stuff!

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