Radio stuff, mostly

[altivo]

Started the day off by playing with getting the computer interfaced to the radio so I can experiment with sound card DSP for digital modes, instead of using my old standalone controller interface from AEA. That was at 5 am, but I managed to avoid making weird noises until about 6:15, when I thought Gary was already up. Apparently he'd just gotten up to go to the bathroom and then went back to bed, so he was awakened by the odd beeps, boops, and assorted hollow whistling warbles. Oops.

Had to work this morning, got home at 1 pm and now the long weekend begins, yay. We decided to go out for lunch (just Boston Market, nothing spectacular) because he wanted to go to an office supply store for some stuff. After we got home from that I went back to work on the computer and radio interfacing while he went off to choir and church. Got it going in receive mode shortly thereafter.

I'm amazed at how much the software control has advanced while I was idling the last couple of years. Using a USB interface to the transceiver, I have complete control of all its features from the computer, including much easier access to several hundred configuration options. The PSK31 software itself is able to copy and display multiple stations at once.

PSK has a very narrow bandwidth. Signals fit in a space only 200Hz wide on the dial. That means that you can have as many as 15 or more perfectly readable signals in the passband of the receiver at once. Today's fast processor and DSP can sort them out and read all of them, scrolling the text across your screen in parallel ribbons. Quite amazing, and a far step from when I was doing packet radio on an Amiga back in the 80s.

My antenna appears to be in decent shape still. There are zero sunspots at the moment I think, so propagation is at its lowest, but I easily copied signals from South, Central, and North America, as well as a few Europeans and a Russian somewhere on an ocean-going vessel out in the Atlantic.

Gotta get the transmit levels adjusted so nothing overloads, and then I'll be on the air again. Certainly before the weekend's out...

Cleared up today and we had sun all day. It's cold, though. C'mon, it's mid-April almost. We should be getting over this freezing nights and chilly days stuff. Even the daffodils looked cold, trying to close themselves back up. Did just small stuff at work this morning, and now a long weekend. Not that I'll be relaxing a lot, too many things that need to get done. Dull stuff, like ironing and housecleaning. A newsletter to get out and a writing project to finish. Oh well, at least the cold is finally losing its grip on my insides.

Comments

[corelog.livejournal.com]

Soudns very cool! :D

[altivo.livejournal.com]

Actually, yes, it literally sounds cool. Morse code, RTTY, and PSK31 are quite musical. Morse I'm sure you've heard before. RTTY uses frequency shift keying between two pitches 170 Hz apart to represent the mark and space of ASCII or BAUDOT code, and has a peculiar and very recognizable "deedle-deedle" sound. PSK31, though, is really strange. It uses phase shifts to represent the ones, and no shift to represent the zeroes in a digital code that can display the same characters as ASCII. The phase shifting makes it sound like someone whistling little warbly notes at the other end of a long hollow tube or hose.

The really amazing thing about PSK31 is that the computer picks out and manages to read signals that you can't hear at all. Often they are so faint that you can barely see a wavy line on the spectrum display.

[octatonic.livejournal.com]

I'd be grumbly if I was Gary but I don't get lots
of consistant sleep. XD

Don't knock Boston Markets, its better than other fast food places.

I'm intriqued about your description of your interface
between your radio and your machine. I can't do it because
my radio is a lil' Yacht Boy but it still sounds interesting.

[altivo.livejournal.com]

I thought it was a bit heavy on the salt, and the seasonings otherwise were a bit "off" but it was OK. The place was deserted except for us, which made us wonder just how well they really are doing.

As for the PSK31 mode, try this page for more information. It really does work, even though it sounds like something they made up for StarTrek. ;p

[cabcat.livejournal.com]

I didn't know you were headphone jockey :) Were you ever a ham radio dude?

[altivo.livejournal.com]

I am. I've had a license for 25 years now.

[cabcat.livejournal.com]

*peeks out your window and sees a big antenna array* Hmmm so I see :)

[altivo.livejournal.com]

Well, actually, you'll have to hunt for the antennas. The big one is about 40 meters long but it's up in the canopy of the oak trees where only the birds notice it. You almost have to be told where to look before you can see it.

[cabcat.livejournal.com]

Don't the squirrels get into them?

[altivo.livejournal.com]

They haven't yet. That wire has been up there for six years now.

[cabcat.livejournal.com]

They're probably stealing your signal ;)

[hrrunka]

Yeah, the Sun's been very quiet recently. I had my H-alpha scope at work early in the week, and resorted to comments like "If there were any sunspots then you'd see..." ;)

A computer engineer colleague of mine is getting into software-defined radio, though I think the kit of surface-mount bits he bought at the end of last year may have been a bit more than he'd bargained for.

[altivo.livejournal.com]

Yeah, you have to be into melting solder big time to get a kick out of doing surface mount stuff. I'm not equipped for it here, and not enthused about the investment it would take to be able to do it right.

Software defined radio is an interesting concept, but I'm not quite ready for it. I'll settle for creating customized signals by fooling the ordinary sideband transmitter into producing them.

[hrrunka]

I just boggle at the things folks manage to do with ham radio... :)