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Things you can do with a Software Defined Radio (2024)

(blinry.org)
940 points mihau | 11 comments | 16 Sep 25 14:35 UTC | HN request time: 1.449s | source | bottom
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megaloblasto ◴[16 Sep 25 15:09 UTC] No.45263373[source]▶
Sadly, you can't really get NOAA satellite images any more. NOAA-15 and 19 were decommissioned August 19, 2025, and NOAA 18 was decommissioned in June. It's my understanding that you'll need a much more powerful antenna to get images from the new satellites. Still, SDR is great fun. It's incredible to realize that all this information is stored in electromagnetic waves and passing through us all the time.
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1. egorfine ◴[16 Sep 25 15:18 UTC] No.45263485[source]▶
I wonder what does it entail to have a NOAA satellite decommissioned? Is it just turned off or is it directed to fall down into a designated area in the Pacific?
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2. megaloblasto ◴[16 Sep 25 15:20 UTC] No.45263500[source]▶
They will continue to orbit for about 150 years, slowly falling towards earth until the drag from the atmosphere burns them up.

"Like many older satellites, the POES satellites do not have thrusters to support a controlled reentry into Earth’s atmosphere at the end of their mission life. Instead, once passivated, they are safely powered down, placed in a non-operational state, and left in a stable orbit. Without onboard propulsion or significant atmospheric drag at their current altitude, NOAA estimates they will remain in orbit for roughly 150 years before gradually reentering the atmosphere and disintegrating."[1]

[1] https://www.nesdis.noaa.gov/news/legacy-orbit-noaa-decommiss...

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3. gmiller123456 ◴[16 Sep 25 15:40 UTC] No.45263759[source]▶
I depends on the orbit. The low Earth ones would usually be de-orbited and fall back to Earth. The geosychronous ones are usually just moved to a parking orbit out of the way to make room for more. If it's in a high but not very crowded orbit, they might just stop using it.
4. egorfine ◴[16 Sep 25 15:40 UTC] No.45263767[source]▶
It sucks they power it down
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5. jandrese ◴[16 Sep 25 16:23 UTC] No.45264354{3}[source]▶
Probably to recover the frequency for a newer satellite. The spectrum they transmit on is quite scarce.
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6. egorfine ◴[16 Sep 25 16:59 UTC] No.45264843{4}[source]▶
Makes total sense, thank you
7. pbhjpbhj ◴[16 Sep 25 17:34 UTC] No.45265261{4}[source]▶
How locked down are they? Should I expect to see a hacker conference talk "how i revived a weather satellite"?

Maybe once they're turned off they're irrecoverable?

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8. rajer ◴[16 Sep 25 19:08 UTC] No.45266513{5}[source]▶
It's not impossible

https://www.youtube.com/watch?v=HT2i7mFpFxM

9. sephamorr ◴[16 Sep 25 22:52 UTC] No.45269325{5}[source]▶
There have been numerous issues in the past with 'dead' satellites waking back up and activating transmitters again, generally making a mess of the spectrum. Some satellites have pyro-fuses on the power lines from the solar arrays that are fired during passivation to make absolutely sure that the sat doesn't ever recharge and wakeup.
10. immibis ◴[17 Sep 25 06:57 UTC] No.45272673{4}[source]▶
You have to have an antenna pointing at the satellite though. That's an additional layer of selectivity.
11. 747fulloftapes ◴[17 Sep 25 10:03 UTC] No.45273855{4}[source]▶
I agree they may want to reuse the spectrum, but I doubt it would be for a new satellite. At least not the stuff in the lower VHF band, around 137 MHz which is awfully close to the airband reservation used for VDL Mode 2 - around 135-137 MHz, IIRC. VDLM2 is in many ways a more modern ACARS.

They'd more likely use higher bands on newer satellites to get more throughput. The GOES birds transmit up around 1.7GHz, afaik and likely higher as well.