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mrgriscom | 5 months ago

SDR is amazing!

Here are some more things you can do with your RTL-SDR after the first 50:

Meteor weather satellite reception (Russian counterpart of the NOAA satellites, but digital, so higher res and in color)

Digital Radio Mondiale -- digital radio but for shortwave

Analog TV -- if you're in an area that still broadcasts this (unlikely), you can receive a black & white picture and closed captioning. If no OTA broadcasts remain, you can use the analog output of a VCR or DVD player

GPS -- rtlsdr is capable of decoding GPS, Galileo, and BeiDou! (Likely not GLONASS since each satellite uses a separate frequency, spreading the signal beyond the sdr's bandwidth)

Hidden secondary audio broadcasts inside FM radio (like the stereo audio hack, but using higher frequencies in the demodulated stream)

Brazilian outlaws and UHF pirates using open repeaters on US military satellites launched in the 70s

TEMPEST / "Van Eck phreaking" where you can remotely read a nearby screen due to leakage from the monitor or video cabling

Instrument landing system -- if you're near an airport you can tune to a runway's ILS frequency and see the signal change as you move from the left side of the runway to the right

Infrared remotes -- stick an IR photodiode in the antenna port and you can demodulate codes from remote controls

Passive radar -- Tune into a very narrowband signal like a VOR or ATSC pilot signal, set your decimation extremely high (i.e., trading bandwidth for dynamic range) and you can see nearby planes in the area from their doppler-shifted reflections of the main signal

discuss

order

matheusmoreira|5 months ago

> Brazilian outlaws and UHF pirates using open repeaters on US military satellites launched in the 70s

This is still happening? I'm sorry but that's hilarious!

https://www.wired.com/2009/04/fleetcom/

ajross|5 months ago

It's not like you can apply a software security patch to a 1970's hardware communication device in orbit. They're likely going to continue acting as open repeaters until their orbit decays and they fall.

747fulloftapes|5 months ago

The receiving IR remotes with an SDR by connecting an IR photodiode across the antenna input sounded like nonsense to me. I googled and could it be you meant people using the IR receiver feature of the RTLSDR's? It may still require connecting a photodiode, but to a different set of inputs.

https://medium.com/@rxseger/receiving-ir-signals-with-rtl-sd...

As to connecting a photodiode to the antenna input, I don't see how that would work, but that may well be due to my limited understanding and imagination.

Do you mean using the photodiode in a photovoltaic mode? Also, presumably you'd have to bypass the tuner and hook to the direct sampling pins on an RTLSDR? Even with direct sampling, wouldn't the 38kHz of IR remote modulation get filtered out by the DC blocking?

mrgriscom|5 months ago

A photodiode (BPV23NF iirc) connected straight to the dongle's SMA connector. Yes, I believe it would be operating in photovoltaic mode, where the incident IR light from the remote control will induce a small voltage. Yes, I had direct sampling mode turned on (but the rtl-sdr.com V3 can do this through the normal antenna port). I pointed the remote at the sensor (admittedly quite close) and saw a signal centered on 38 kHz in the waterfall, and was able to export the binary pulses.

jasonjayr|5 months ago

This video shows a Passive RF/Fiber connector that seems to work pretty reliably for broadcast tv.

https://www.youtube.com/watch?v=wIN7DVGBbKM

I imagine, provided the IR's frequency can be sampled by the SDR, it would look like fairly wide band bursts that could be decoded? Especially if you just treat the SDR as a ADC Oscilloscope

transpute|5 months ago

  remotely read a nearby screen
"Eavesdrop on HDMI from Unintended Electromagnetic Emanations with GNU Radio" (2024 paper), https://github.com/emidan19/deep-tempest

Displaying malicious image causes HDMI cable to emit LoRa packets, https://github.com/XieyangSun/TEMPEST-LoRa

  passive radar
"Build a passive radar with software-defined radio" (2022), https://hn.algolia.com/?query=passive%20radar

SEC-T 0x11 (2025) on evil maid defense, https://www.youtube.com/watch?v=ScwNIWzk4RQ

> Do you like feeling safe about leaving your expensive stuff in your hotel room? Have you ever had anything stolen out of your room, or discovered someone has gained access to your room while you weren't there? .. what about .. other rooms? Maybe not EXACTLY a hotel room? I've presented on securing hotel rooms in the past, but adding home assistant, zwave devices, co2 sensors and millimeter wave radar it's become a whole new game

  SDR is amazing!
Video tutorial series with book references, https://gallicchio.github.io/learnSDR/:

> We use the GNURadio software along with RTL-SDR and ADALM-PLUTO hardware to explore the world of digital communication. We build up to a simple QPSK modem and rudimentary GPS reception.

LibreSDR firmware, https://github.com/F5OEO/tezuka_fw

> official [PlutoSDR] firmware updates are no longer focus on new features for SDR enthusiastic people.. tezuka.. aims to be Universal Zynq/AD9363 firmware builder for.. PlutoSDR, Pluto+, AntSDR (e200), LibreSDR