Sunday, January 22, 2012
Propeller takes to the air
Today I have been playing around with MEPT beacon code on my Gadget Gangster Parallax Propeller board. First I wandered over to Jeff, KO7M's blog and borrowed his WSPR beacon code.
WSPR was the thing I originally wanted to try when I decided to get the Gadget Gangster: I hadn't even heard of OPERA at that time. But I was unsure whether I would be able to generate the FSK frequencies WSPR uses: four tones separated by about 1.48Hz. Jeff decided to shoot as near as he could and programmed for a 2Hz separation of tones, and found that the signal was decoded by K1JT's WSPR program. So no problem!
I measured the RF output from the Propeller board and it was somewhere in the region of 25 to 40mW, depending on which measurement method you believe. I also looked at the output using my oscilloscope.
It wasn't a pure sine wave, there's obviously some harmonic content there, but it was not as bad as I feared it might be. As I would be using my MFJ magnetic loop on 30m, which has a very narrow bandwidth, I decided not to bother with a low pass filter for the sake of these initial trials. I watched the seconds tick over on my shack radio-controlled clock, started the beacon and was soon rewarded by several WSPR spots!
Because WSPR is a time-synchronous mode I had to start the beacon when the seconds ticked over to 00. This brought to light a problem Jeff had already observed: the Propeller drifts. The drift seems to be worst during the first few minutes of operation, so leaving the beacon running so it can reach a stable temperature would appear to be the solution. However that is not so easy when you have to power it on at an exact time. I will need to look in to implementing a real-time clock for WSPR, unless I want to interface a GPS receiver to the Propeller - which is certainly possible and something else I hope to try as I'd like to have a go at making an APRS tracker.
An advantage of the OPERA mode is that it is not time synchronous so I can leave the beacon running in that mode with an arbitrary delay between transmissions. My first OPERA transmission also produced several spots, including reports from fellow bloggers PC4T and G4NKX.
I can also generate Morse and QRSS beacons using the Propeller chip. There is still a lot to do to reach my goal of a multimode, frequency-agile beacon, including adding a PA and some switchable bandpass filters. But so far this project has turned out to be easier than I thought it would.
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| Gadget Gangster in use as a 25mW WSPR/Opera beacon |
WSPR was the thing I originally wanted to try when I decided to get the Gadget Gangster: I hadn't even heard of OPERA at that time. But I was unsure whether I would be able to generate the FSK frequencies WSPR uses: four tones separated by about 1.48Hz. Jeff decided to shoot as near as he could and programmed for a 2Hz separation of tones, and found that the signal was decoded by K1JT's WSPR program. So no problem!
I measured the RF output from the Propeller board and it was somewhere in the region of 25 to 40mW, depending on which measurement method you believe. I also looked at the output using my oscilloscope.
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| Output waveform from Parallax Propeller on 80m |
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| WSPR spots for 25mW Propeller beacon |
An advantage of the OPERA mode is that it is not time synchronous so I can leave the beacon running in that mode with an arbitrary delay between transmissions. My first OPERA transmission also produced several spots, including reports from fellow bloggers PC4T and G4NKX.
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| OPERA spots for 25mW Propeller beacon |
Labels: Construction, OPERA, Propeller, WSPR
Friday, January 20, 2012
Four metres
There are a number of things I'd like to do radio-wise this year. One of them is to get equipped for SSB on four metres.
I have spent quite a lot over the last two or three years on 2m SSB and have very few contacts to show for it. My QTH in the Cockermouth Black Hole seems to be prevented by the Lake District mountains from receiving good signals from other English stations by normal propagation. I don't even experience much in the way of tropo openings here. The only real 2m DX I have worked are a handful of Sporadic-E (Es) contacts into Spain and Portugal. One thing I have learned is that 144MHz Es, which is a pretty rare thing in any case, is considerably rarer the further north you get. I was ill and recovering from my brain operation during the peak of the Es season last year but as far as I can tell from DX Sherlock no Sporadic-E openings on 2m reached this far north during 2011 so I didn't actually miss anything.
Six metres is another matter. I have made lots of contacts on the Magic Band even though my 6m antenna is just the addition of two quarter-wave wire elements to my multi-band attic dipole. Four metres won't be open as often as Six but it should sustain Sporadic-E propagation a lot more often than Two does. And now that many European countries have granted their amateurs 4m allocations I think there could be a good chance of working some summertime DX.
The plan depends on my finding space in my attic antenna farm for a 4m antenna. One of the first home improvements Olga and I will make this year is to replace the central heating boiler and we're advised that the most efficient types available now heat the water on demand and don't need a header tank or pipes in the loft. I'm a bit apprehensive about letting workmen loose in the attic when I'm not sure whether I'm capable of moving around safely up there to check my antennas are OK and repair any damage. But getting rid of the tank and copper pipes will make a bit more space for the antennas and hopefully allow me to mount a 4m Moxon on the rotator where the 2m one currently is.
I will also need a radio for 4m SSB. I guess I'm looking at getting a Spectrum Communications transverter for this. Probably a ready built one as I'm not really sure I can manage to assemble that complex a kit any more. I wonder if anyone has successfully modified an Elecraft XV50 for 70MHz?
I have spent quite a lot over the last two or three years on 2m SSB and have very few contacts to show for it. My QTH in the Cockermouth Black Hole seems to be prevented by the Lake District mountains from receiving good signals from other English stations by normal propagation. I don't even experience much in the way of tropo openings here. The only real 2m DX I have worked are a handful of Sporadic-E (Es) contacts into Spain and Portugal. One thing I have learned is that 144MHz Es, which is a pretty rare thing in any case, is considerably rarer the further north you get. I was ill and recovering from my brain operation during the peak of the Es season last year but as far as I can tell from DX Sherlock no Sporadic-E openings on 2m reached this far north during 2011 so I didn't actually miss anything.
Six metres is another matter. I have made lots of contacts on the Magic Band even though my 6m antenna is just the addition of two quarter-wave wire elements to my multi-band attic dipole. Four metres won't be open as often as Six but it should sustain Sporadic-E propagation a lot more often than Two does. And now that many European countries have granted their amateurs 4m allocations I think there could be a good chance of working some summertime DX.
The plan depends on my finding space in my attic antenna farm for a 4m antenna. One of the first home improvements Olga and I will make this year is to replace the central heating boiler and we're advised that the most efficient types available now heat the water on demand and don't need a header tank or pipes in the loft. I'm a bit apprehensive about letting workmen loose in the attic when I'm not sure whether I'm capable of moving around safely up there to check my antennas are OK and repair any damage. But getting rid of the tank and copper pipes will make a bit more space for the antennas and hopefully allow me to mount a 4m Moxon on the rotator where the 2m one currently is.
I will also need a radio for 4m SSB. I guess I'm looking at getting a Spectrum Communications transverter for this. Probably a ready built one as I'm not really sure I can manage to assemble that complex a kit any more. I wonder if anyone has successfully modified an Elecraft XV50 for 70MHz?
Labels: Sporadic-E, VHF
Wednesday, January 18, 2012
Hacked!
I looked at the G4ILO's Shack website this morning and with a sinking heart saw this:
It appeared that my site had been hacked and an image inserted that said KZ.AM/STOP SOPA. (It was bigger than my screen so I couldn't capture all of it.)
Upon further investigation it appears that the site toplisted.net has become defunct and an image from amateurradio.toplisted.net has been replaced by the one shown in the screen grab. So solving the problem turned out to be a simple matter of removing the links to toplisted.net. Big sigh of relief!
I don't know whether the hacked image contained any other payload. I wonder how many other ham radio sites are affected?
Because of things like this, running a website is a hassle compared to the blog which is maintained and updated free of charge by the blog host such as Blogger. I'd prefer to just concern myself with the content of the site not the technical aspects.
It may be time to review the future of the website, especially considering that some of the software it contains (such as VOAProp) is gradually being made obsolete by changes to the Windows OS and third-party data files.
It appeared that my site had been hacked and an image inserted that said KZ.AM/STOP SOPA. (It was bigger than my screen so I couldn't capture all of it.)
Upon further investigation it appears that the site toplisted.net has become defunct and an image from amateurradio.toplisted.net has been replaced by the one shown in the screen grab. So solving the problem turned out to be a simple matter of removing the links to toplisted.net. Big sigh of relief!
I don't know whether the hacked image contained any other payload. I wonder how many other ham radio sites are affected?
Because of things like this, running a website is a hassle compared to the blog which is maintained and updated free of charge by the blog host such as Blogger. I'd prefer to just concern myself with the content of the site not the technical aspects.
It may be time to review the future of the website, especially considering that some of the software it contains (such as VOAProp) is gradually being made obsolete by changes to the Windows OS and third-party data files.
Tuesday, January 17, 2012
Simple keyer complete
At last, I finally got the QRP keyer using KD1JV's Simple Keyer Chip boxed and working.
As usual, nothing went according to plan. There must be some relative to Murphy's Law that states for any homebrew project the case will be just too small for comfort. A related rule is the one which guarantees that after you have drilled the case, the position of one of the switches or sockets will be in just the place where it fouls one of the components.
After my first attempt at getting it into the box the keyer was dead as a dodo. This turned out to be because I had forgotten to break one of the tracks on the Veroboard.
After the second attempt the keyer responded to the function button but there was no keying. That turned out to be because one of the connecting wires had broken at just the point where it was soldered. With my eyes as they currently are that took a while to spot.
When I had resoldered the connection and put the board into the case for a third time I noticed that another connecting wire was hanging on by one strand of copper. Lesson: don't use hookup wire from China, it is made from inferior grade copper.
This had taken me a day, so I decided to put the project aside until I felt calmer. The next day I re-made all the connections using new wire, put the board into the case one last time and it actually worked! But Murphy had one last laugh: Now I couldn't find the four screws for the Hammond case I was using. We searched everywhere. Fortunately my parts box had another Hammond case which sacrificed its screws for the benefit of the keyer. Later, Olga and I managed to find suitable replacements in the local DIY emporium so the other case won't be wasted.
This Simple Keyer is just what I need for the simple QRP rigs that only work with a straight key. The code speed is easily adjustable and there are two memories, one of which can be repeated as a beacon. I don't need more sophistication than that for QRP work.
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| The completed keyer |
After my first attempt at getting it into the box the keyer was dead as a dodo. This turned out to be because I had forgotten to break one of the tracks on the Veroboard.
After the second attempt the keyer responded to the function button but there was no keying. That turned out to be because one of the connecting wires had broken at just the point where it was soldered. With my eyes as they currently are that took a while to spot.
When I had resoldered the connection and put the board into the case for a third time I noticed that another connecting wire was hanging on by one strand of copper. Lesson: don't use hookup wire from China, it is made from inferior grade copper.
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| View from the front |
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| View from the back |
This Simple Keyer is just what I need for the simple QRP rigs that only work with a straight key. The code speed is easily adjustable and there are two memories, one of which can be repeated as a beacon. I don't need more sophistication than that for QRP work.
Labels: Construction, CW, Morse
Sunday, January 15, 2012
Propeller does WSPR
Through Eldon, WA0UWH I have discovered another blog to add to the blogroll: that of Jeff, KO7M. Jeff is interested in a lot of the same things I have been (including light aviation: an ambition of mine when I was in my 20s but which I could never afford to take up.) But what really piqued my interest was that he has just got a Parallax Propeller to generate a WSPR signal.
This is one of the things I was interested in trying. But I never got further than wondering how to implement the fractional frequency shifts of the WSPR signal, which uses 4 tones shifted by just under 1.5Hz from each other. Jeff has apparently found that a 2Hz shift is good enough to be decoded, allowing WSPR to be sent using the integer frequencies the Propeller chip can easily generate.
Once I have finished the Tiny Keyer project and can get back to the Propeller I will be trying this myself. My ambition at the moment is to make a multi-band multi-mode (OPERA, WSPR and perhaps QRSS as well) standalone beacon with an LCD panel to enable me to choose the band and mode. We'll see how far I get, but having two other people working on the same ideas should certainly make the task easier!
This is one of the things I was interested in trying. But I never got further than wondering how to implement the fractional frequency shifts of the WSPR signal, which uses 4 tones shifted by just under 1.5Hz from each other. Jeff has apparently found that a 2Hz shift is good enough to be decoded, allowing WSPR to be sent using the integer frequencies the Propeller chip can easily generate.
Once I have finished the Tiny Keyer project and can get back to the Propeller I will be trying this myself. My ambition at the moment is to make a multi-band multi-mode (OPERA, WSPR and perhaps QRSS as well) standalone beacon with an LCD panel to enable me to choose the band and mode. We'll see how far I get, but having two other people working on the same ideas should certainly make the task easier!
Labels: Construction, Microcontrollers, OPERA, Propeller, QRSS, WSPR
