Video intro to receiving HF with Software Defined Radio

[VK2FUNK]

@ VK2DAG:

Lots of connections

So you have your USRP (or FunCube or RTL2832U/DVB or..) plugged into a windoze box running HDSDR with the "EXT IO" running BorIP so that your Linux box running GNU-Radio can access the data (audio?) from HDSDR. Is this right?

Yes, this is correct. GNU Radio can get the data from HDSDR. BUT! All the devices I use also have native support in GNU Radio, so you can skip HDSDR/Windows altogether. Sometimes I use one, other times both - just depends on what's going on.

Now I don't have a USRP (or FunCube or RTL2832U/DVB or..) I have a SDR-IQ and some SoftRocks (with 192 KHz card). So the only way I can play with GNU-Radio is connected the SDR-IQ to the linux laptop or access SDR recording across my network. Is this right?

IIRC SDR-IQ uses USB, but I'm not sure what it looks like to the computer (an audio card? or a custom interface?). SoftRocks are also USB now? The trick is that any 'SDR' that is in fact a quadrature receiver (that outputs analog signals to be received by a sound card, or combined in a single unit with integrated audio codec like the FUNcube Dongle) can be used with GNU Radio, because you can just use an Audio Source block and take each channel as I and Q respectively. Tuning the radio is the tricky bit in that instance (since you need to know how to 'talk' to it, e.g. FUNcube appears as an HID deice you can send special commands to). I'm honestly not sure what sort of support there is for that hardware in GNU Radio (e.g. if streaming/control is more complex), so other people might have to weigh in here... I've only seen them used with mostly closed-source Windows apps.

Need to get me one of them cheap TV tuner things now

Yeah they're alright for the price! $20-$30!

BTW: It got a mention on Hack a Day! http://hackaday.com/2012/03/30/working- ... uner-card/

[VK2DDS]

Your video made it to the Slashdot front page, nice one!

[VK2LK]

APCO25 decoder?

Yep. I worked on that project with a bunch of other guys around 4 years ago. We managed to crack their rather flaky encryption implementation (DES-OFB and ADP) as well.

Check the project out at http://op25.osmocom.org

Cheers,
Matt

[VK2FUNK]

Your video made it to the Slashdot front page, nice one!

Thank you! Although I think perhaps they may have meant to put up either of the follow two (instead of the one they did, which doesn't specifically deal with the cheap SDR dongle):

http://www.youtube.com/watch?v=Z0hEquzLsWU (Windows)
http://www.youtube.com/watch?v=FUQd9HOVTk8 (GNU Radio)

[VK2FUNK]

Where do ya get other sinks, sources etc from? And how do I get to see them, once I have them, in Radio Companion?

A good place to look around is CGRAN: http://www.cgran.org
It's also a good idea to search the GNU Radio Discussion mailing list: http://www.gnu.org/software/gnuradio/mailinglists.html

They will only turn up on GRC if there exists a GRC Block definition for them. There's a lot out there that unfortunately is not yet easily accessible in GRC.

So are there windows drivers for the USPR?

Yeah, it requires a generic USB driver called 'libusb', which is what my Windows plugin uses. Ettus Research has released their 'UHD' software that then talks to the USRP via libusb.

When I installed your ExtIO_USRP stuff I notice I now have another choice for a device when I start HDSDR. Will you be adding the DVB dongle thing drivers for it?

Yes, it actually already supports it, as well as the FUNcube Dongle and network streaming from the BorIP server (and then sending the raw samples to GNU Radio via UDP). See the table here: http://wiki.spench.net/wiki/USRP_Interfaces#Help

One of those DVB things working at 64 MHz is going to be the bee knee's for looking at the IF of FT-817. Makes for a nice compact portable setup, and with 3 MHz coverage that's heaps more then the 192 KHz I have been using.

Just keep in mind that the DVB stick is a cheap option (you get what you pay for!). It's only 8-bits (lower dynamic range), and there are various impediments that prevent it from being a 'true' SDR receiver (I think there are still mysterious stages in the signal chain that need to be switch off, but no public datasheets). Plus I'm not familiar with IF taps to modern HF transceivers, but obviously you need to check the available bandwidth after filtering from the previous mixer stage.

I am still finding my away around Ubuntu. Not being used to using a GUI in linux and I am pushing the limits of the old laptop I installed it all on. Still got to get my head around the workings of the different blocks and connecting them together.

If you can, I recommend upgrading as SDR/DSP is quite CPU intensive. And there are lots of pretty graphics too that you can generate in realtime if you have sufficent grunt. Also consider Mint Linux if you end up installing a Linux distro again elsewhere.