For fun, I’ve got my new RFSPACE SDR-IQ running on my laptop using Spectrum Lab and monitoring the 30m QRSS beacon subband. I enabled its HTTP server, and now have set up a little cronscript to copy its display to my webserver once a minute. You can see an example display below (showing KC7VHS, AA5CK and WA5DJJ) or you can click on the link below, and get the live version on QRSS.info
K6HX QRSS Grabber.
I’m not sure why the frequency display on the right is wrong. Anybody have any ideas? I probably have missed something in the configuration of Spectrum Lab, but it’s rather like operating the Space Shuttle…
Well, we are beginning to get some lightning in the area, so my radio is disconnected, but before I did so, I managed to hook Spectrum Lab up to my SDR-IQ radio, and got these two DFCW signals: KC7VHS and WA5DJJ.
Paul, M1CNK, has a very nice webpage that details his QRSS beacon, constructed as several different kits assembled as modules. Very cool.
Over on NT7S’s Ripples in the Ether blog, he presents a link to a project by Joachim, DL1GSJ, a very nifty little SDR designed to operate near the 30m QRSS watering hole frequncy. It uses pair of subharmonic mixers, whose operation I admit I don’t completely understand, but I’m bookmarking the circuit for later consumption.
de draaggolf ~~~~~: 30m Subharmonic I/Q-SDR Receiver.
A while go, I posted a link to AA5CK’s website and his use of the iduino as a QRSS keyer. He used a little oscillator/buffer from Nightfire Engineering along with a home brew, single transistor amplifier.
So, I ordered two. And built one. At $7, who could resist?
It works, but it obviously isn’t very pure. I’ll get some a snaphot of the oscilloscope output sometime, but it is obviously flat on the bottom of the cycle, with a rather sharp and triangle peak. The tone sounds very
harsh in a receiver. It very obviously needs some kind of output filter. It does appear to be very close on frequency, maybe only 5 hertz low. The peak-to-peak voltage swing into a 50 ohm load was very nearly 2 volts, meaning that the output power is somewhere around 14mw with the 9 volt battery I was using as a supply.
Overall, my “ugly construction” 40m oscillator with buffer that I cribbed from EMRFD seems much cleaner. I suspect that in part this is because the vakits.com oscillator doesn’t have a tuned buffer amplifier, but that’s just my intuition.
I’d like to boost the output power to around 100mw (or maybe even a bit more) (perhaps with a class C amp) and obviously add an output filter, and then get it on the air.
This morning I was scanning my WSPR logs and my MEPT screenshots for the night. It seemed to be pretty good. I had quite a number of spots into Australia overnight: both from VK6DI (who is nearing the end of his time in VK6 land, we hope to see you again back on the eastern side of Australia) and from a newcomer: VK2DAG. Checking back through my MEPT screenshots, I was hoping to get some nice shots from VK2ZAY, but he was pretty marginal, and there was very definitely some spreading in frequency. But I was pleased to find a few nice beacon messages from Eric, WY7USA, running at 500mw:
Addendum: A couple of hours later….
Alan, VA3STL posted a nice list of captures of his QRP beacon on his blog, including a link to a spot of him that he got from my grabber. I didn’t notice it then, but now that I’m back on 30m, I’m seeing it nicely at the moment:
Well, I’m not sure that the Softrock I put together is working entirely well. I’m beginning to believe that the transformer that I wound might be bad. My receiver seems a bit deaf, and also seems to have only about 20db or so of opposite side rejection (I’m getting images of signals on both sides of the center carrier frequency). I’m a bit stymied by the fact that I only have my macbook in a place where it can be used to decode the softrock, and the software for it is, well, to a first approximation, there isn’t any. I did a bit of hacking, and took a recording I made and extracted this Morse code recording, which I’ll archive here as the first that I ever got.
Morse via my Softrock
I’ll have to work on it some more in the future, but for now, I’m back to beaconing with my FT-817.
This morning, I have a particularly nice array of signals streaming across. First NM5DV at the top. He put a T-attenuator onto his Softrock transmitter, knocking his 1watt down to around 400mw. WA5DJJ is banging in again as usual (he’s on virtually the entire day). You can begin to see WB3ANQ’s snake, running in at 1.5watts at the moment, and then down at the bottom, W1BW’s flying W and of course my regular as rain Australian DX, VK6DI.
Addendum: WA0UWH has a similarly nice display this morning, including my own signal front and center:
Bill posted today about W3PM’s design for a dedicated WSPR beacon transciever. It’s very slick: basically a crystal oscillator that can be mixed with the signal from a PC sound card, then piped through a narrow crystal filter and through an amplifier chain into an antenna. Check out the PDF, it’s quite nice.
SolderSmoke Daily News: Homebrew WSPR from W3PM
WA0UWH announced that his awesome grabber was back in a new temporary location, fed by satellite internet. I had some difficulties getting images earlier in the day but it’s up now, and you can easily see my DFCW beacon, sending K6HX.
This morning I see that Dan, NM5DV has worked out his issues with this Softrock, and is now putting out a nice signal up above WA5DJJ. Yesterday, his signal made it briefly into Belgium alongside WA5DJJ: I’m wondering if anyone has been using Softrocks as beacon transmitters.
Down below, you can perhaps see hints of VK2ZAY as well as VK6DI. VK6DI will be shutting down operations from Western Australia soon and moving back to Eastern Australia. Too bad: I’ve really enjoyed these DX opportunities.
I’ve had the beacon off for a few days, but I think it’s time go get it back on. 10 minute repeat time.
Addendum: I was on IRC, and got a quick note from NM5DV indicating that he thought I had gone off frequency. Yep, I had bumped the knob on my radio while I was resetting the beacon (now operating near the top of the subband, around 10.140090). You can see that the 20hz shift was quite clear. 🙂
Alan, VK2ZAY apparently has changed his beacon to send MT Hellschrieber, in addition to his FSK CW.
If you look carefully, you can see VK2ZAY in letters. Very neat!
After more or less a full day where I made almost ever mistake possible (exaggerating) on gettin my Softrock Lite built (which it is, except for connectors, it’s ready for final testing), I put the grabber back up in receive mode. I didn’t bother to get the WSPR beacon back up for now, but that will return shortly. Scanning through backlog didn’t reveal too much of interest, except for a very brief 15 minute period where VE1VDM and W1BW were booming in. Here’s an exemplar:
I also noted that my frequency stability is vastly improved without the thermal cycling of transmit going on. Lines appear flat, nobody is wandering up and down, proving rather conclusively that it was me.