Ten years ago I proposed to my best friend.

She said no.

I had a black and white solid state Sony TV in my bedroom when I was growing up.

Aside from dialing into late night TV programmes my parents prohibited, there were two buttons that switched between VHF and UHF.

Toggling the UHF button allowed me to tune into police radio.

Being able to capture this via that TV felt close to magic, and I think probably went a long way to forming my associations between technology, mystery and discovery.

An article in TV Guide back in the 70s said you could tune in to tornados too. You'd dial it down below channel 2 (IIRC) and you could pick up EM static generated by a tornado within range.

I thought the same thing. But it does happen, my neighbors started dating and eventually married after meeting over ham radio.

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.

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

Hunting for Space Radio Pirates on the US Military Fleet Satcom Satellites[2023]

https://www.rtl-sdr.com/hunting-for-space-radio-pirates-on-t...

prisoners of gravity: a favorite from_my_youth

1) https://inv.nadeko.net/watch?v=-deHrvY2b08&list=PL08AD26AD9C...

2) https://inv.nadeko.net/search?q=prisoners+of+gravity

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.

I was joking about the billion dollar idea.

My actual "MVP" was some kind of automated neighborhood newsletter, that'd monitor emergency services radio traffic, and put together some kind of "here's what happened in your neighborhood" daily newsletter.

Maybe I could get it packaged in a hardware/software package that let anyone set one up in their neighborhood.

But I mostly got stuck in privacy concerns. I'm not sure it's a valuable public service to let people know that, for example, someone had a heart attack a few blocks over.

I did think about the scientific value of some kind of statistical database that process and recorded emergency services calls though. But mostly, my ideas for commercial and moral opportunities were half-baked at the point that I discovered citizen.

One of the technical challenges I came up against was finding transcription software that could semi-accurately transcribe UHF/VHF radio traffic. However, it looks like there's some progress that's been made there since I last checked: https://www.rtl-sdr.com/radiotransciptor-real-time-radio-spe...

> I encourage you to make a product even if something similar exists.

This is very good advice: we often give up on "great ideas" once we find that they have already been done.

But the vast majority of people we consider successful did not invent anything completely new, they just made a better kind of XYZ, sometimes not even that dramatically different. If you think about it, it's a much more logical path to success than expecting to be the next DaVinci.

That was the vibe I was getting when visiting the site, they seem to understand fear pretty well. Stay away for your own mental health :-)

About 24 years ago, I was working at Honeywell and they were pulling down data from the GOES satellites for use an a GA service. It required a giant satellite dish on the roof of the office building and a top-of-the-line (for the time) Pentium 4 for decoding.

Do not post affliliate links.

https://www.amazon.com/dp/B08HGQXC7C

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...

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.

Yes, that seems to be what mine is doing as my ecobee thermostat is able to read info about peak usage times from the mains. I didn't know about the latter part though, I never imagined electric companies were making a play for the internet (though it seems like an obvious thought in retrospect).

In the early 2000’s there were efforts to provide broadband over power lines (BPL). I think one of the biggest obstacles was the radio frequency interference it generated.

And its "last mile" friend of using the in-wall cable as Ethernet drops, too, e.g. https://www.tp-link.com/us/powerline/ (but I don't think it holds a candle to actually pulling cat 5 or 6, for clarity)

If it's low enough bitrate, wouldn't you be able to read that by putting an antenna or loop of wire near the mains? I assume they use a documented standard.

I believe the v5 is a Nooelec and is comparable to the RTL v3. The RTL v4 is the latest chip. They both have different strengths and weaknesses tho.

https://www.onesdr.com/rtl-sdr-vs-nesdr-which-one-should-i-b...

ive got ~15 deployed sensors/transmitters and I haven't touched a single one in 14 months since initial setup. its super reliable if you can get your receiver/antenna somewhere that works well.

WAY cheaper than the other options too.

I'm spoiled. One of my receivers is on a second story and has great line-of-sight to a bunch of houses and a parking lot (where I assume I get a lot of my TPMS "hits").

I concur, but for a different reason. This is repeating a narrative that was found to be a policy decision by hospitals in the US. That sentence isn't quite right but i don't have time to formulate it better.

The pocsag data, if this detailed, would have mentioned giving specific patients specific medicine that would then cause their O2 sat to drop. Since that isn't mentioned, either they forgot, or maybe there's an axe to grind.

Nevertheless, having grabbed pocsag in my area i don't remember seeing much PII, mostly room numbers, if anything.

You could perhaps compare notes with the author of [0] who did manage to achieve multilateration with rtl-sdrs using TDoA.

[0] https://jenda.hrach.eu/

I want to experiment with stationary receivers around the perimeter of my property. It would be fun to document and pinpoint every RF source on my land, but I'd settle for being able to reliably find my dog.

I always forget that the US still has bandwidth caps.. something which has never really existed where I live for fixed broadband.

Warning: My German legalese isn't very good and this is not legal advice. I unfortunately know very little about how the German court system works and where to look up stuff.

The law[1] is worded like this:

> (1) Mit einer Funkanlage (§ 3 Absatz 1 Nummer 1 des Funkanlagengesetzes) dürfen nur solche Nachrichten abgehört oder in vergleichbarer Weise zur Kenntnis genommen werden, die für den Betreiber der Funkanlage, für Funkamateure im Sinne des § 2 Nummer 1 des Amateurfunkgesetzes, für die Allgemeinheit oder für einen unbestimmten Personenkreis bestimmt sind.

The law basically says that you may only listen to (or take note of in comparable way[2]) messages that are:

1. For you, the operator

2. For amateur radio operators according to the Amateurfunkgesetz

3. For the general public

4. For an indeterminate group of persons (I think that's an accurate translation?)

For me, a big question regarding aviation and marine traffic monitoring is what "unbestimmten Personenkreis"/"indeterminate group of persons" actually means. Since "die Allgemeinheit"/"the general public" is listed separately, I'd assume it's a distinct group from that, and to me the previous commenter's "meant for any member of the public who happens to be flying a plane nearby" sounds like it could fit that description. I'd argue, for example, that police radio is for a "determinate" group of persons, police officers and dispatchers working for the government, whereas aviation and maritime traffic is an "indeterminate" group of people, people working for all sorts of airlines, shipping companies, recreational pilots/boaters, who happen to be around the same area.

If anyone has any links to cases where this law was tried in relation to aviation or maritime communications, please share them, I have been struggling to figure out where to look for this stuff, on top of that, the law was also renamed or moved around, which makes it extra confusing.

[1] https://dejure.org/gesetze/TDDDG/5.html

[2] Might be related to this weird ruling, where a judge in a case about some ADS-B receiver decided that it was ok because rendering the position of aircraft wasn't "listening to" (as in, literally hearing) the traffic: https://openjur.de/u/130555.html - This decision is probably moot now, due the addition of "take note of in comparable way". The judge briefly mentions that actually listening to the traffic could be violating the law, but I am not sure if this point was ever properly litigated.

I cant speak to 2G networks, but 5G (and 4G) are amazingly simple to get started using OpenAirInterface. With a USRP B210 I had a 5G network running from a bare Ubuntu install in under 30 minutes. I used a smartphone and some cheap (blank, user-writable) SIM cards to connect and test it.

Gabe just quit his dayjob to go full-time on SaveItForParts, so hopefully we'll be seeing even more cool stuff in the near future. Me personally, I'm hoping for a collab between him and Jeff. They've had some interaction already (Jeff donated Gabe a spare computer he had lying around) so maybe... That would be epic if it did happen.

My impression is that gnuradio is fine for prototyping/poc, but has issues in its design when you try and run production workloads with more complex workflows (ie, writing custom Mac layers/ workflows that involve heavy feedback, etc. you end up having to do a a lot of hacking around with the message passing infrastructure).

That being said last I used it extensively was v3 so maybe v4 is better. Did they get rid of thread per block and allow you to have a single thread service a sub signal chain? I remember that the number of context switches between threads, and balancing latency vs buffer sizes was a pain in the rear.

Is there anything like this that can go down to 15 MHz or lower? including transmit and several analog modes of modulation USB LSB NFM WFM AM CW at least

for anyone reading this actually interested, just FYI an improved model "HackRF Pro" is due for release in the next month or so, is backwards-compatible, and is what will come in at that $400 price tag.

years ago, there used to be a very abundant market for used or chinese clone HackRF One units, but i haven't been able to find any these days.

Yeah I dont know any SDR above 6GHZ but also other than mmwave 5G I also dont know much radio that is above 6Ghz in general

Looks cool, except it uses USB2 which seems limiting in view of bandwidth.

Why not, if you want to address all those frequencies you need the highest capability, so GHz range not MHz range.