Fifty Things you can do with a Software Defined Radio

I just wanted to post that I can't find anything about it being forbidden, but there is actually a link in the post[1]. So basically the situation is:

Mit einer Funkanlage 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.

Which in English would read something like this:

With radio equipment you are only allowed to listen to, or take note of in some other way, those messages that are addressed to the operator of the equipment, those messages that are addressed to ham radio operators in general, those messages that are addressed to the general public or for an undefined group of people.

This is of course absolutely unenforceable, untraceable and generally ridicoulus, but it is what it is. Imagine your neighbours having very loud arguments (or very loud 'horizontal discussions') in a clairaudient flat, and then telling you that you cannot listen to it. And being correct legally ;)

[1] https://www.buzer.de/5_TTDSG.htm

I recall Finland had a rule that you can listen (how else would you hear the next message meant for you on maritime VHF), but you can't repeat things publicly or act on knowledge gained from that. Now, why would that be? Well, it's mostly to minimize sensationalist news reporting of people's accidents, misfortunes and such, whether maritime or over old school police radio (before it was encrypted). Discourage ambulance chasing, that sort of thing. It's just another part of the European attitude toward privacy.

There are also FCC regulations in the US that relate to receiving signals under certain circumstances: https://www.fcc.gov/consumers/guides/interception-and-divulg...

Reminds me of Germany in WW2 where citizens would get locked up or worse for listening to the BBC to get non-government approved news.

Do you happen to have a write-up of this? I'd be interested in building the same capability, although I doubt we have the same provider.

ADC sensitivity is influenced by quite a few things, some of them pretty unintuitive (e.g., some interference from unwanted signals in the RF passband can be a good thing if it provides a source of dithering that allows weaker signals to cross bit boundaries).

Bit depth is surprisingly far down the list in overall importance. To understand why, look up "FFT processing gain." Consider that sigma-delta converters are 1-bit ADCs, yet the S-D topology is used for many applications that require wide dynamic range.

What frequency is your gas meter transmitting at?

In this case what is a good SDR device that does TX?

The hackRF is a popular one. If you want to do anything at range, note that you'll need an RF amplifier and an antenna.

Also note that TX is heavily regulated, and you should get licenced before you start blasting.

Is there a very low bandwith equivalent of Internet via SDR?

There's open source software to build your own LTE tower using an SDR. That's not really low bandwidth, though...

Most of the SDRs are receive-only. The ones that do transmit have really low power. The LimeSDR is 10mW and most are in that range. That means need amplifier or two to make it usable.

Packet radio is done with amateur radio. There is both VHF/UHF ones that use normal radios, and 2.4GHz ones which usually use Wifi with dishes. There aren't BBSes because there isn't much point with Internet, and there isn't much point to Internet access when have mobile. Plus, it isn't allowed to provide non-amateur Internet access.

Have any links or sources for tutorials on getting into those several are intersting