Use Your PC Sound Card as a Test Instrument

A friend of mine recently sent me a press release touting free software that would turn your PC’s sound card into a function generator. As it turns out, the press release was somewhat misleading–as they often are. The software is really only free to use for 30 days, and then you have to pay $25 to obtain a registration key. That got me thinking that there must be some software out there that’s really free, so I did a Google search for “pc sound card function generator.”

One of the links it came up with was a page listing electronics related software from an online encyclopedia. That page has links to a function generator program that’s really free by Dr. He Lingsong of Huazhong University of Science and Technology. According to the page:

“Digital Signal Generator is a virtual signal gerenator that use sound card or LabView compatible A/D card to outport signal. It can produces white noise signal, sine wave, square wave, trigon wave, beat wave, sweep sine wave and a signal defined by a windows WAV file. It is free and easy to use.”

It doesn’t do pink noise–whatever that is–like the first program, but it does do a swept sine wave, which I’d guess is more useful than pink noise, anyway. The page also has a couple of links to free programs that provide oscillator functions.

Other useful Google results include:

Update 9/23/04:
Brad, AA1IP sent me a link to the Amateur Radio Soundblaster Software Collection. As Brad notes, it looks like it’s all in German, but page down and you’ll find English. It’s a great collection of programs that do ham related tasks using the sound card, including SSTV, RTTY, fax, and audio frequency analysis.

What caught my eye was several links to voice keyers. Call me lazy, but now that I’ve started using SSB a little, I’d love to have a voice keyer to call CQ for me.

Update 9/24/04:
Brad just now e-mailed me a link to .WAV Audio to EPROM by Harry Lythall – SM0VPO. This is the voice equivalent of the simple CW keyers I wrote about earlier. According to Harry,

“You will be able to record two seconds of decent quality AF on a 2764 EPROM, with a 4KHz sample rate….” A 27128 should thus hold 4 seconds, a 27256 8 seconds, a 27512 16 seconds, and a 271024 (or whatever their omenclature is) will hold 32 seconds.”

I haven’t timed a CQ, but you should be able to get away with a 27512, which you can get at Digikey for less than two bucks.

Brad notes, “Harry includes playback logic, too– essentially, you set up a couple of counters and crank the EPROM’s addresses.” The circuit even includes an 9-bit D/A converter that uses a transistor, some resistors, and a couple of gates. VERY COOL!

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