Hams, any opinions on hackrf?

[szatox]

I'm mildly interested in radio com, I've been occasionally looking at SDRs on the market and thinking about what I'd like to do about maybe joining the hobby, and I found this one device which _maybe_ would be a good start for me, but I'm not quite convinced and don't want to spend 500$ on a fancy paperweight, which is roughly what I'd need to cough up for the device and antenna.

So, hackrf.
+ wide frequency range, 1MHz - 6GHz.
- 8 bit ADC, I was surprised it can be this small and still work
- rx amp is said to be being easy to fry
- sold as a radio lab test equipment, it's unclear if it's only for legal reasons, or because it overall is a bad receiver with a very wide frequency range as its only redeeming quality

Does anyone here know this thing?
Would it make a scanner suitable for getting my feet wet? Is it sensitive enough to pick up signals form hams, weather broadcasts and so on?
Could I use it to snoop in on emcomms in case of disasters, or something like that? I mean, 500$ is 500$, would be nice if it had a second purpose besides being a new toy...
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[Banana]

I am still in the same situation and started with a simple USB SDR and some software. I've started (and still are) with https://www.rtl-sdr.com/rtl-sdr-quick-start-guide/

So far I do not regret it and it is a very good starting point to get the feet wet and get to know if any better products will be necessary. Because a good product alone does not make something good. And yes it works with linux. Haven't tested it with gentoo yet.
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[szatox]

That rtl doesn't go anywhere nearly as high into microwave spectrum, but man, I could get it so much cheaper it actually is a tempting suggestion.

What feats have pulled using this dongle?
I know I could google it, but there surely is a world of difference between anti-proffesionals (because money flows in the opposite direction) calling themselves amateurs and newcomers, so I can't really expect to get the results from brag stories born on the internet.
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[eccerr0r]

Question is what exactly do you want to monitor?

Most microwave stuff is encrypted, I doubt many people are using FM or SSB or something that's not digital/QAM/CDM/... on microwave frequencies. Most of that stuff is on cellphones and stuff and that's really short range, encrypted, and illegal to monitor. Yes there's some satellite but most of that's also encrypted.

Emergency comms are trending to P25 and encryption on that is part of the standard.

Or are you just planning to listen on the amateur bands? Or what's left on analog/unencrypted?

I was thinking about getting an rtl-sdr but really haven't found a good use statement for it. Sure I could monitor anything I wanted but not much I really want to hear these days... Only thing is perhaps monitoring my power meter transmitting updates, but not much else. Otherwise I'd probably at most use it for a waterfall display for HF perhaps.

What I do need to do is get CAT control working on my hf rig... put in the UART but it's not working :(
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[szatox]

> Question is what exactly do you want to monitor?
I don't know, I'm new to this business. I want to see what's on air.
Amateur bands sound good, meddling with wifi with its 40, 80 and 160 MHz wide channels is definitely out of the question; I'm not willing to pay the price of a rig big enough to capture this traffic (and regular wifi adapters are better suited for that job anyway), but bluetooth should be doable on pretty much any SDR reaching into 2.4 GHz band.
What else is there? Weather broadcasts? LoRa? Even if I'm unable to decode contents of some transmissions, I might still be able to figure out what kind of transmissions they are and maybe say something about the source.
Who knows, maybe hunting anomalies would be interesting. I won't know until I try.
The thing I liked about a radio scanner going up to 6GHz is that it should cover pretty much all frequencies with a practical use; I doubt there's anything going on in higher bands.

What's up with those encrypted emcomms? I saw some info about training camps for hams regarding participation, so it looked like it should be available for civilians too, even if you're required to get a license before you transmit anything. Or is it another case of different countries doing things differently?

Regarding legality, I'd rather focus on technical stuff here, like setting expectations for the signals I might be able to find and receive and what are those devices capable of (if you have any experience with them), since what's legal varies from country to country and needs to be sorted out locally anyway.
Fortunately I don't have to obey USA's legislation. Unfortunately, politicians here are just as good at wasting paper.
Did you know in my country it's technically illegal to own a hammer? It is a weight on a stick, which makes it legally a weapon, and if the weight is wider than the stick, it must be registered and you need a permission to own and use it. I mean, nobody will bother stopping you in a hardware store, but according to the weapons law it is _technically_ illegal.
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[Ralphred]

[Banana]

Here are two ready to use images for raspberry which include a lot of software to tinker with. It should give you an idea what software is available

https://github.com/luigifcruz/pisdr-image
https://github.com/dslotter/HamPi
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[lars_the_bear]

[szatox]

> First thing, learn how to turn an "old car radio" in to your own "personal, one mile radius" pirate radio station*.
Some boys want to be astronauts, some want to be be astronomers. It is a good path to take, I'm just not quite sure I want start with with jumping all the way to the other side, especially since there is a thing I need completed before I can give my full attention to building something else from scraps.

> Here are two ready to use images for raspberry which include a lot of software to tinker with. It should give you an idea what software is available
Thanks, sounds good, I happen to have a spare Pi4, kinda wanted to turn it into a NAS, but this may actually be a better use for it.

> The problem I have with it is that all the signal processing is very CPU-intensive, and my computer overheats. So, other than running some sample applications, I haven't done a lot with it. Works fine under Linux, though, with GNU Radio and others.

How did it fare in terms of sensitivity and selectivity for example? Or did you just plug it in, saw that it talks to the computer and went back to a more specialized rig?
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[lars_the_bear]

[eccerr0r]

The encryption on a lot of police/fire/etc. communication is mainly to prevent interference over making sure data isn't intercepted. Some of this emergency communication that happens over encrypted radio is also simulcast over the internet to prove that they aren't doing it for hiding communication versus ensuring interference free (mainly to prevent tricking first responders of fake emergencies.)

That is not to say amateur bands are still being used for emcom, after all ARES is all that along with the usual public service uses of amateur radio. And in the USA pretty much you're allowed to listen all you want, just don't decrypt if you're not the intended target of the communication (and of course no encryption on amateur bands.)

There are other things that may be interesting. A lot of weather satellites transmit their imagery unencrypted and you can receive the photos directly without waiting for it to show up on local news. But that doesn't show up in the microwave frequencies, it's like slow scan TV where it takes a while to receive a frame. (note that this differs from radar imagery which needs to be computed from on ground transmitters and you probably can't generate an image directly.)

This also differs from the USA NWS broadcasts that happen over FM. These are audio broadcasts and nothing special about them. Similar to the time transmitters like WWV.

The other aspect of (amateur) radio is that the expectation that you'll be transmitting. If all you're doing is listening, that's not really amateur radio... and transmitting is regulated mainly to prevent tragedy of the commons.
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[szatox]

> To be fair, the RTL-SDR was about one fiftieth the price of my Icom. It blows my mind that it works at all. It certainly works better than the price would suggest.
Good to know. It is a vague answer, but it does work as a gauge.
Yeah, it blows my mind that an 8 bit adc is enough to pick any signal at all. Makes me wonder at what frequency do they sample that signal to make up for low spacial(?) resolution.

> The other aspect of (amateur) radio is that the expectation that you'll be transmitting. If all you're doing is listening, that's not really amateur radio... and transmitting is regulated mainly to prevent tragedy of the commons.
Yeah, I get that part. I might make it the second stop.
Thanks for details explanation of the other things, that should make a decent starting point
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[zen_desu]

I got a RTL-SDR just to dig deeper into LoRa stuff. I have a variety of LoRa transceivers from different manufacturers and of different specs and wanted to see if I could setup a radio to sniff stuff for more debugging.

I was never able to get anything to actually decode the LoRa broadcasts, but I was able to see them.

For ~$30 a RTL SDR is a great toy at the least and is essentially plug and play on Gentoo, you just need to get something like sdrpp.
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[szatox]

Thanks for your comments everyone, in the end I decided to go ahead and get the rtl-sdr dongle with a set of antennas suggested by the store.
While I'm waiting for delivery, what kernel modules should I ensure are available? The official howto seems to only mention stuff that must be blacklisted.

zen_desu, I see there is gr-lora_sdr in guru overlay.
Also, some time ago I stumbled over this experimental lora transmitter implemented completely in software. https://www.cnx-software.com/2024/03/28/lolra-project-transmitting-lora-packet-without-radio-using-ch32v003-esp8266-or-esp32-s2-mcu/ Actually using it is probably not a good idea, but it is an interesting piece (with really bad security implication for basically any processor with access to sensitive data)
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[zen_desu]

[eccerr0r]

Encryption be the death of amateur radio.

Fortunately LoRa isn't amateur radio. While interesting, it's not really that interesting, it seems end user/end use focused rather than learning about radio. Alas seems the prepper club is interested in LoRa just due to it being turnkey infrastructure-less and you can even run encryption over it unlike amateur radio, which is likewise infrastructure-less.

Kind of makes the amateur hacked wifi-based mesh networks obsolete because LoRa doesn't need an amateur license to use?
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[szatox]

> Encryption be the death of amateur radio.
What do you mean by that? I know encryption is not allowed on those bands, but that alone doesn't seem enough to spell doom.

Anyway, I've been playing with that rtl and trying different things for a few days.
Hooked up js8call to sdrpp (via netcat and pw-cat because it's audio sink is just smart enough NOT to work with pipewire directly, so had to use network instead), and I see quite some activity in 40m band, but here's something that really puzzles me: js8call picks up fragments of messages which seem completely drowned by the noise to me (SNR up to -28db), but at the same time it misses quite a lot of much stronger signals which look and sound just like js8call messages.
What am I likely to have screwed up? My time is synchronized with ntp; automatic time drift mode kinda helps sometimes, but not as much as I'd expect if it was an issue with a clock.
Also, turned down output volume in sdrpp quite a bit, since js8call's gauge was stuck in the red. I didn't think it's possible to overdrive a virtual wire carrying PCM numbers, but here we are.
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[eccerr0r]

If data is encrypted over amateur radio, then commercial use could use the bandwidth and claim plausible deniability that they were using it for amateur use, leaving no more bandwidth left for amateurs to play with and learn - which was the intent of amateur radio.

hmm. it's possible that the waterfall might look like valid data but it actually isn't? Not sure. Have not tried js8call, but used wsjt-x ft8 but using an actual transceiver with limited bandwidth. And yes it's possible to overdrive, if all the samples are 255 or 65535 it would show up as red and very strong signal, but odd harmonics were introduced with the railing and data is lost.
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[szatox]

> If data is encrypted over amateur radio, then commercial use could use the bandwidth and claim plausible deniability that they were using it for amateur use
And then sue you for talking over them? That would be funny. Can companies even apply for ham licenses?
I don't know power dynamics there, but I always though the licenses exist mostly to keep the amateurs off of the commercial (and military) bands rather than the other way around. Are bands infested with civilians doing random things really that attractive to businesses which need relatively large volumes of data reliably delivered in a timely manner?

> it's possible that the waterfall might look like valid data but it actually isn't
It is possible, but not very likely in context of the bits I did decode: Several fragments of messages with understandable words, with most parts visible on waterfall but not received. A contact from a single sender participating in a ham contest, when there were like 10 other people on the same channel, who also went silent at about the same time. Stuff like that.

> yes it's possible to overdrive, if all the samples are 255 or 65535
Sure, having a bunch of those in a row would certainly indicate the signal got clipped, and I wouldn't be surprised seeing something like that after a conversion to analogue and back to digital, but the noise I have here was just generated in already digital format, and it sounds like proper static with occasional "dripping" of ft8.
Weird. I have a hard time imagining what could go wrong in this particular scenario. Even resampling the stream shouldn't make the ripples that much louder.

BTW, wsjt-x in portage is disabled by date. I tried to launch it, but it wasn't important enough for me to look for a newer version or patch the test out. There are more than enough other things to play with in the meantime
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