Runs 3.7 GnuRadio along with a whole slew of tools and antennas to boot. I even put the guy who runs the Wall of Sheep... on the Wall of Sheep. He was running a Logitech clone dongle. Pwned.
My device is GPL3 and on https://gitlab.com/crankylinuxuser/siginttablet . It costs around $150 to build.
I don't have a HackRF but I managed to get the "Hello World" flow, i.e., listen to FM broadcast radio going nicely with a cheap RTL-SDR by following lesson 1, but changing the sample rate.
The version of GNU Radio in the Ubuntu apt-get repos for 18.04 is fairly recent but the GQRX project has a PPA which includes GNU Radio which will hopefully be updated more frequently.
With default Ubuntu I had problems with the WX slider not moving. I didn't realize that WX widgets are old and the advice is to use QT. WX is removed in this latest version.
FWIW, I've since switched to Kubuntu on the same hardware and all widgets work well including WX but I have followed advice and now use QT.
The sound sink seems to work better if you bypass PulseAudio. Give the sink a device name, probably hw.
I'm eagerly waiting for one of these that I preordered. https://airspy.com/airspy-hf-discovery/ I don't have it yet so I can't swear by it but every report from those who have one seems to be very good if you want a general purpose receiver. It covers 0.5 kHz (yes 500 Hz) to 31 MHz and 60 to 260 MHz so not as wide as some but ... I'm mostly interested in HF so plenty wide enough for me.
Also, if you do get a license, register it to a PO box.
On PO Boxes, I don't think it does much to thwart a person looking for your address. It's one single barrier, but anyone can find anyone's legal mailing address via whitepages/public record using only a name and location.
A $10 ham license opens up a significant amount of bandwidth, and power up to 1500W.
I'd grab an RTL-SDR, a thumb drive with Pentoo, and then you can play around in the live environment very easily.
This dude https://www-users.cs.york.ac.uk/~fisher/modem/ wrote V.32 soft modem stack for SGI Indy back in 1996
I remember reading back in the day in hacker zines about magic police modem tapping boxes, but no idea how would that work in the age of echo cancellation.
Which would be the easiest way, unsure if you could do it purly in GNU Radio as not that up upon it, though software modems been around for a while, and more optimised code for the task. Historically the earliest software modems date back to the 90's.
Firstly, it's not a new idea. Folks use JS8call (formerly FT8call). It's quite sophisticated and can work even below the noise floor. Folks have even gotten it to work in pretty ridiculous conditions. It has comically low bandwidth but works at comically low power.
That said, the only place I think this would be "clandestine" is in urban environments where there is a lot of reflection. Modern electronics and antennas get the benefit of very high fidelity simulation, so finding a signal with professional gear (especially if it's cutting edge and understands modern maps) is pretty wild. I saw a demo of a very expensive system that used Google Earth as its UX a few years ago, and it could do some amazing things.
Even in cluttered environments with low power transmitters, it still isn't very secretive. Amateur radio does this thing called "fox hunting" where they use a variety of handheld elements to quickly track down low power signals. Some of these contests get pretty technical, with the target transmitter being highly directional on some axis and deliberately casting false reflections, and lately they're entirely solar/lifepo4 so they're power constrainted.
But folks with a bit of training and practice can find them really quick.
If you want to be clandestine, then actually what you want to do is overlay your network over existing networks so that your traffic is difficult to isolate from a computationally infeasible flood.
Depending on how creative one was about the locations and operation times of the transmitter, I'd expect it'd be pretty difficult to find.
What about a transmitter temporarily sent aloft on a balloon, model rocket, or drone, then making its brief high-bandwidth transmission and then parachuting or landing, being retrieved by its operator who then disappears until the next transmission from another location?
It might even be disposable, and potentially either deliberately sink itself in to an ocean or other difficult to access place, and/or self-destruct to make recovery and forensics more difficult.
This isnt true. High data rate requires large channel size, which is certainly more commonly found in >1GHz portions of radio spectrum that require line of sight. But, a 10MHz channel is just as fast at 400MHz as it is a 4GHz. HDTV doesnt require line of sight to gets tens of megabits on VHF/UHF channels.
And even worse than the answer to that (nowhere) is that in the USA the data rate limit is actually in terms of symbol rate, not bandwidth used, to a mere 300 baud for the bands that have regular non-line of sight propagation.
I never implied you could? Its certainly possible in VHF/UHF, though (for licencees).
> And even worse than the answer to that (nowhere) is that in the USA the data rate limit is actually in terms of symbol rate, not bandwidth used
Sure, but those limits only apply for HF and longer-wavelength frequencies. You're welcome to do 256QAM in the microwave range, for example.
>You're welcome to do 256QAM in the microwave range, for example.
Which gets back to line of sight propagation (tropo is not common) and everything I said in my first post.
I've tried the home to car omnidirectional link thing on 902-928 MHz. All that matters is line of sight. I tried a 25w bidirectional amp (ham general license) and that didn't help. I tried bringing the ubiquiti transceivers w/broadband hamnet firmware all the way down to QPSK modulation and the narrowest channel I could. I even tried using narrowband 56k telemetry dongles. I customed designed and built my own microstrip based filters for the front ends.
The only thing that really helps, and it's not enough, is height above terrain. When I go park my car on the hills outside of town megabits are possible. But the slightest hill or valley losing LOS kills it.
I haven’t used GNU radio in maybe a year, so I don’t know what this release brings.
I am currious to hear about how CPU intensive are the 2 versions, wxgui vs Qt.
If you like it and want to take things further, buy a limesdr mini or bladerf or something. By then you'll feel constrained by the rtlsdr and know better what you want.
As a non-licensed radio operator you can get a cheap USB connected receiver and use GNU radio to receive, demodulate and decode all sorts of signals.
It's fun to learn about how to decode certain signals. You start with a simple AM demodulator to listen to music stations and before you know it you're tracking airplanes and hacking keyfobs.
It's a really powerful and cool way to explore the EM spectrum around you right now.
Another interesting use can be reading your electric meter (and the ones of your neighbors), using GNU Radio or https://github.com/bemasher/rtlamr .
Another one, is reading TPMS from your car wheels (or cars that are passing by): https://www.rtl-sdr.com/receiving-decoding-tire-pressure-mon... , https://github.com/jboone/tpms
I just want a GUI tool which lets me take data streams, mix them, add them, run a function over them, preview them as a scope, power spectrum or IQ chart, play them through a speaker, decode them as mpeg, GPS signals, or anything else.
It seems GNU radio offers all that, but is so fiendishly hard to use it's easier just to write code in C to process my data as I want and plot it with matplotlib.
And for hacking car key fobs.
I used bladeRF last.