Monday, June 11, 2012

The SDR Chronicles (#1: Installation)

Many months ago, I decided to add an SDR (Software-Defined Radio) to my array.  After this, I spent altogether too long agonizing between the venerable Perseus and the new Excalibur Pro.

Both of these are DDC (Digital Down-Converter) radios.  Essentially, an untuned RF front end goes to an A/D converter, and is down-converted by a mathematical algorithm for output over a standard USB 2.0 cable.  What used to be the IF strip, where the real action in a superheterodyne receiver goes on, is now done by software.  What used to be the detector stage is now a digital demodulator, making waveform changes a snap. Finally, the result goes to the computer sound card for D/A conversion into audio for the computer's speakers.

The Perseus is an established product, a bit old, but with a large and dedicated user base which shares many great things that various smart people have learned to do with it.  The slightly more expensive Excalibur Pro was vapor until about a year ago, and its userbase is tiny by comparison, but anyone who ever tried it said it was a darn good radio.

Finally, I went with the Excalibur Pro.  I think it's the broadcast audio that finally tipped the scale, though obviously nothing using computer audio will ever match the soul stirring roar of the R-390 through a good stereo system.  Still, it is clean and non-fatiguing, which is more than I can say for most of the better radios used by utility DXers.

My nice new radio arrived last Friday, and was summarily unpacked. It's a neat looking little metal box, covered in a futuristic looking material that looks pretty indestructible.  The antenna downlead, snap-in USB connector (supplied), and DC power connection are on one end, which is considered the back.  Extra points to WinRadio for using a linear power supply rather than a wall wart.

The front has a main power button and a minimalist blue LED.  Once you power up,  the LED blinks in a fair semblance of Morse code to show the radio's state of readiness.  "S" means you're connected and waiting for the software to start.  A somewhat elongated "A" means you're good to go.

Installation is just a matter of following steps.  Install the software, cable up the radio, turn it on and let Windows find it.  Let it install the driver, then connect your antenna through the BNC-SMA adapter supplied, and light up the software.

At this point, there should be spectrums dancing and audio happening.  The box was factory set to 10 MHz WWV.  I should have had time.  Time with latency, but time.

Nothing.  No dancing spectrums, no audio, no nothing.  An hour or so of various troubleshooting steps got nowhere.  ????

I was damned if I'd send my nice new box back to Grove before trying it on another computer.  And so I did.  Same process, exactly, except that when WinRadio's app was started, the radio gave a little relay click and WWV lit up the screen and speakers.

At last, I had found time.

The radio was connected back to the big computer, a 6-core 3.2 GHz liquid-cooled production machine with the horsepower to do some serious radio processing.  This beast was going to be its friend, one way or another.  For whatever reason, this time it was.  The radio gave the same little relay click, and everything's worked great since.

Computers.  Can't live without 'em, can't live with 'em.

(To be continued.)