SDR - Conspiscuous by its absence

[W1GUH]

Software Defined Radio

It was a hot topic over on another board 2-3 (maybe 4) years ago, but I just realized I haven't seen it at all here. Thought there might be a separate forum for it, but didn't find it with a quick look.

When I was looking at it, it looked like it'd be a whale of a lot of fun to play with. It seemed like you could play with parameters...bandwidth, skirt slope, all that stuf to your heart's content.

Anyone doing it? Is it all it is (or was) cracked up to be?

[K3VR]

Lots of us are using homebrew and commercial SDR equipment. I have a 756 ProII that's used a nice bedside receiver ever since I got my SDR.

Flex Radio (http://www.flex-radio.com/) has more information. The FLEX-5000™ is One of the Highest Performing HF+6m Amateur Radio Transceivers Available at Any Price with 2 kHz Spacing, Two-Tone 3rd Order Dynamic Range of ~100 dB (ARRL test method).

Flex also makes a military version for SUNAIR (http://support.flex-radio.com/Downloads.aspx?id=199).

There will be forums at Dayton. There is a mailing list available at the site above. Here is the development group for the High Performance SDR open source design project (http://hpsdr.org/).

Here's an ARRL article (http://www.arrl.org/tis/info/sdr.html) on SDR. Any specific questions?

[N2RJ]

I've been playing around with the SoftRock (http://groups.yahoo.com/groups/SoftRock40) SDR receivers and transceivers.

If you're on CW or PSK31 on 40m or 30m I can give you a demo.

[AG3Y]

Here is the URL for the softrock group :

http://groups.yahoo.com/group/softrock40/

Lots of good information on that neat little rig ! 73, Jim

[wy6k]

I second the comments made above about the Flex 5000. You will love the filter shape and the control over the filters that you have with the Flex and you will love the spectrum scope. Also quite popular is the transmit audio flexibility (read "width"). It takes a while to get onto "visual tuning" with the mouse and keyboard. I also got the optional "knob", the outboard USB tuning knob and find the combo of the mouse and the knob to be very handy.

I would add that the SDR-IQ is a very interesting SDR. It is only a receiver, not a transceiver. But it is very interesting, fun, and useful. It is much "lighter" than the Flex 5000 running PowerSDR software - meaning the software puts less load on the cpu. As a result, it is less fussy and is not prone to crashes and hangs. I don't think it has ever hung on me. It's only $400, so is lower risk as an entry point to SDR-dom than is a Flex. FWIW, I "like" the SDR-IQ better than the Flex, whatever that means.

Mike

[WA9SVD]

I don't deliberatrely search the airwaves for SDR's, but a couple of weeks ago, I heard a fellow in NY State using one (A Flex) in a roundtable discussion. It sounded fine; no way to tell it was any different than any other radio. A really strong signal, but so were others from the area; peopagation was good on 20 that day.
The radios ARE out there, but radios such as the FLEX are a bit pricey, and often the high-priced radios are bought by the contesters, not necessarily the experimenters.

[AG3Y]

I was going to post this in "Computers and Software" but since I couldn't find my old thread, and since it is somewhat appropriate to the subject, here goes:

I asked about using a program called "loop.dll" with the softrock board, a soundcard, and two different software modules, "Rocky" and "MultiPSK". MultiPSK is supposed to support loop.dll, but I cannot get it to do what I think it should do for anything!

Well, I bit the bullet, ( about a $35.00 bullet, not too bad ) and went ahead and bought a second soundcard and slipped it into my computer. Here are the results.

Lets call the new soundcard "A" or the default card, and the sound that is built into the motherboard "B", the secondary soundcard.

By feeding the output of my receiver into "A", and then feeding the "wave" output of "A", (which is actually the output of a SDR program such as "Rocky") to the second soundcard ( "B" )'s INPUT, I can then use a program such as MultiPSK to demodulate the audio stream. In essence, I am using "A" as an audio Digital Signal Processor ( DSP ) and "B" to decode the audio, just as if it were being fed by a very selective, modern DSP receiver!

The beauty of this setup is that you can use ANY program that supports soundcard digital protocols, in conjunction with your favorite SDR setup, and if there is any audio coming from the radio that is outside the passband set by the SDR , it is NOT heard or detected by the digital decoding program! Currently, Rocky only supports PSK31, RTTY and SSB, if I remember correctly, and only shows one line of decoded text. But there is no limitation if two soundcards are used, one for the SDR/DSP, and the other for the demodulating of the data stream!

Standard audio can be fed to the setup too, with just a slight change in the setup. If you would like to learn more, give me a PM or we can talk about it here.

73, Jim

[KA4DPO]

Pretty clever for an old guy Jim, can you do SSTV with it?

[N2RJ]

Actually if you used PowerSDR, it integrates with the virtual audio card (VAC) pretty well.

Only problem is that powerSDR is very CPU hungry. On my P4 2GHz (yeah, old machine, circa 2002) it crawls if I go above 48kHz sampling rate. We're getting new computers anyway (I have my eye on a mac pro) but for now that cramps my experiments a little.

However, I like the simplicity of Rocky, but I don't like that the source code is not available. But anyway it's still a great piece of software... written in delphi, but I won't hold that against Alex. ;)

I'm actually thinking this may be easier in Linux where you can create a sound device that is simply a pipe from the SDR software decoding the baseband signal. I've yet to try it though. Maybe one day when I have some spare time.

[AG3Y]

A resounding YES !

I just experimented by looping the output of Soundcard #1 into the input of Soundcard #2 . I used two instances of EasyPAL on the same machine ( a 3.5 Ghz Gateway ) and achieved a signal/noise ratio of in excess of 52 db with that program's quality monitor. The waterfall and waveform display was textbook flat ! This test was performed using DRM Mode B and 2.5khz bandwidth .

So if I can do that with this machine, I ought to be able to do just about any kind of digital application that would be called for on the HF bands, and probably VHF/UHF high speed modes, as well !

BTW, soundcard "A" is the new Soundblaster Audigy 24/96 card, and soundcard "B" is the onboard Realtec HD chipset .

Thought you might be interested !

73, Jim

[KD7TCS]

Anyone doing it? Is it all it is (or was) cracked up to be?

Ask Ten Tec, I've heard they sold a radio or two in the past few years. :D

[wy6k]

Ask Ten Tec, I've heard they sold a radio or two in the past few years. :D

Why do you mention Ten Tec in this context?

Thanks,
Mike WY6K

[n4bfd]

I got sucked into the SDR thing and ended up getting a SDR1000 to play with. Before I was using a TS-830 and a FT-857D... either of which I hardly turn on now.

Several years ago I built a dual core AMD Opteron based computer and it is running PowerSDR and a FA-66 at 196khz without a hiccup at low buffer rates.
I enjoy it tremendously, and have gotten good audio reports on transmit. The built in RX and TX EQ is nice. I am using a cheap condenser mic (MXL V67) jacked straight into the external sound card, the FA-66 is nice in that it provides 48v for condenser mics.

Anyway, I love the interface, and it is nice to have the brick wall filters, and the receive is just excellent. I use it with a surround sound system and it fills the room with ham radio goodness. :)

I like running the digital modes mostly though, and for that it is nice as well, the waterfall is the cleanest I have ever seen on any program I use, clicking on the pass band skirts and dragging them over to just cradle a signal in the pile just takes a couple of seconds. They are brick walls, anything a few hertz outside the passband is just not heard nor does it affect the AGC.

The panadapter is addictive, I love parking on in the middle of a band... seeing a signal, clicking on it... and hearing the station that just literally keyed up, no vfoing up and down the band to get to something. Just click and BAM you are there. It has helped be get a few DX stations before the pileups start.

Used SDR1000s are a great buy for the money, not much you can get out there for 1000 plus or minus a bit that will give you this much fun in ham radio. My father came over to check it out one night.. and ended up buying a used SDR1000 the next day. There are also a couple of locals here that have gotten the 1000 and 5000 recently so it has been fun hearing what everyone has learned... it has become a big topic on the 2 meter repeater here in town.

[W1GUH]

Sure appreciate all the info...it only makes me want to get into it more. Got one "small" problem, tho', and that's my HF hostile QTH. I'm working on that, as time allows, and hope to get a receiving situation that would make SDR possible for me. This is strong incentive.

Thanks, again.