Tag Archives: wspr

Post Field Day Report on K6HX Beacon Operations…

So, part of my incentive on working on my WSPR beacon was one of my coworkers decided to try to do some operating from the local Emeryville Marina, and I thought it might be nice to use the opportunity to try to pack up my WSPR setup and see if I could get some spots using solar/battery power.

I wrote up some of the early experimentation to get the beacon working, but as of then I hadn’t actually gotten on the air. To do that, I needed two things: an antenna and (to be a good RF citizen) a low pass filter to make sure that I wasn’t scattering horrible harmonics everywhere. While it was true that I was outputting a scant 10mw, I thought that being a good citizen was important.

I had some yellow T37-6 cores lying around from a previous bout of homebrew exploration, and dug out an article on constructing harmonic filters by the awesome (but sadly SK) George Dobs, G3RJV. I dug out some copper clad and wired up the filter using some islands that I punched out of scrap copper clad board. I am a total novice at this, so the board layout is terrible and stupid, and the leads are too long: in short, everything I did should be viewed with skepticism.

But as crappy as it is, it seemed to work. I snapped a quick picture of the output as it goes to my antenna, and the previously ugly triangle-ish wave now resembles a reasonable sine wave.

I must admit that I was somewhat befuddled by the Vrms as measured by my scope. The equation for output power suggests that power equals Vrms squared divided by the resistance. If we assume my antenna was a nominal 50 ohms (it’s not, but let’s pretend) then this would indicate an output power of nearly 70mw, which doesn’t really make sense. My antenna had only been “tuned” in the grossest sense, and probably had an SWR of around 2.5:1, which suggests that it’s characteristic impedance was probably a lot higher. For the purposes of WSPR, I configured my output power as 20mw, which I thought was probably still generous, but in the right ballpark. I made a note to myself to figure this out later.

I still needed an antenna. While cleaning my garage, I found a pair of 20m whip antennas and an MFJ 347 mini dipole mount. I mounted these on a small piece of conduit, and then built a quick stand to hold it up, consisting of a 5 gallon bucket, a small round of particle board that I had left over from another project, and four pieces of two by fours to act as feet. Here it is, setup on my back patio. Yes, I know that the antenna is mounted too low to be good or efficient. This entire project was designed to be a hack, and for maximum ease, not permanence.

I set it up and home and set it beaconing. I didn’t get the torrent of spots that I had gotten when I had used a similar setup with 5w of power (using my FT-817) but a few minutes later I did get a spot from KA7OEI from DN31, a distance of about 933 km.

Huzzah! Thought I. I was ready for field day. Mind you, the entire thing was still just a pile of breadboards constructed out of wire. I decided to use my Chinese charge controller and a 20w panel to drive it and to recharge a 7aH lead acid battery. I packed it all up and headed to Emeryville on Field Day.

I’d like to report success, but the fact is that once I got it set up, it was apparent to me (by a lack of blinking lights and LEDs) that it wasn’t working. I wasn’t sure what was wrong, but I had failed to bring my laptop so debugging it in the field seemed like it wasn’t going to happen. After a couple of hours, I decided to pack it in. Sad.

Setup, but disappointingly didn’t generate any RF or even a single spot.

The next day I unloaded it from the car and tested it out. The Arduino and the LCD unit seemed completely dead. I reflashed the code onto a new Arduino Nano, moved it all to a single breadboard, and reset it up in the backyard, and it has been beaconing on 20m, entirely powered by solar since then.

Since then, it has been spotted by 15 unique stations. By far and away the most reliable connection has been to KA7OEI-1, who has heard it 337 times in the last week. ND7M comes in next, with 118 spots. Distance records are pretty much evenly split between AI6VN/KH6 in Hawaii, and WD4ELG in North Carolina.

I made a small map which updates frequently, showing all the spots for the previous 24 hours. You can view that from my home webserver, at least until I get bored with it and take it down. I used the Python matplotlib to generate the maps, this one being an example.

I’ll probably try to get this up more or less permanently, and may add a small RF amplifier to boost its output to around 100mw. I will probably also shift to using an ESP8266 based module so that I can monitor and control the system via WiFi. I’ll update you when I get that going.

Hope you enjoyed.

On properly operating a WSPR station…

Anyone who is subscribed to the QRP-L has likely been subjected to a long string of complaints against WSPR in the past week or so. This began with a generic complaint against a “consistent carrier” on 7.040. This rapidly decayed into a long series of rants against WSPR. Since I’m rather more fond of WSPR than the average QRP-L member, I chose to defend WSPR’s place in the ham radio universe.

But amidst the general complaints, there are a few points which they make which we should all take to heart. First of all, in the United States we are not allowed to operate automatic beacon transmitters below 10m. This means that you have to be in control of the station, and operate it in a manner consistent with Part 97 regulations. I’m not sure what that really means in the context of this mode, but I suspect that it means that running your beacon all night while you sleep isn’t actually legal, as fun (or useful, I would argue) as it might be to see those spots from New Zealand that occur at 4:30AM local time when you wake up and have your coffee. I believe that all hams should endeavor to operate their stations in accordance to regulations, so I think that we as WSPR operators should be at the control point of our stations when transmitting WSPR. I also think that this point of legality isn’t adequately emphasized in existing documentation, so new users of the mode may be unaware of this issue, so it would be great if we had a more prominent notice on WSJT’s site, and on wsprnet.org.

Beyond simple legality though, I’ve seen that the QRP-ers have some basis for being irritated beyond the mere legality of this operation. In the last 24 hours, I’ve logged one particular station who has operated at 100w output power, and for quite a while, was transmitting about 50% of all slots, including many back to back slots. This resulted in spots with a SNR of +5 over distances of 12000km. This isn’t a WSPR, it’s a rock concert. I think its good to keep WSPR at QRP levels or ideally QRPP levels. And let’s keep our transmit percentage down to 20% or less. As WSPR has become more popular (and it has become much more so even in the last few months, with dozens of stations on 40m and 30m) we’ll need to reduce the time we spend transmitting to mitigate collisions.

And let’s be especially careful around 40m, okay? 7.040Mhz isn’t the best choice of frequency, frankly. Lots of old time rock bound QRPers still claim it as their own, and while nobody owns a frequency, we should be courteous to all hams.

Listening to WSPR activity

Over the past few days, I finally got a windows box up and running so I could run the official WSPR executable from WSJT. In the short time I’ve been listening, I’ve gotten quite a few spots from stations who haven’t been able to hear me. I made a quick map of all the sites I’ve heard:

Stations I've heard using WSPR

Stations I've heard using WSPR

I’ve deleted a couple of bogus spots that also got “decoded”, both of which were stations which were in the middle of the ocean, and which no one else heard before.

Apologies to all those who have been using my grabber, I will soon return it to operation by tapping audio and feeding it to both setups in the near future.

Aircraft reflection? Or something else?

This duplicates a posting I made on the wsprnet.org website.

Aircraft reflection? Or something else? | WSPRnet
On Saturday, Jan 10th, I had my transmit-only beacon that I wrote sending both a visual MEPT indicator (the MV that you can see in the attached image) and the WSPR beacon, and tried out a simple program that simultaneously records, and later makes an FFT display of that portion of the band.

It seems to work!

I’m curious though about the brighter of the wspr messages visible here, which seems to have a shadow which arcs down to meet it. Is this the result of an aircraft reflection? There are some fairly close stations here (such as NN6RF) which conceivably could be reflecting off aircraft landing at Oakland airport, but I’m surprised that the signal level could be so high on the 30m band. I believe that such reflections can only occur if the source is reasonably close to the aircraft, correct?

aircraft

I see a couple of other, similar traces in the 2 hour recording I did, which you can peruse here.

K6HX beaconing on 30m with WSPR/MEPT

Okay, I hadn’t been doing any WSPR beacon operations since before Thanksgiving (which was also before my new callsign) and I was kind of bored today, so I dug out my power supply, tuner and interface and set my computer beaconing again on 30m. It’s a combination beacon: using WSPR above 10.140100, and a visual “MV” written as part of a sawtooth in the visual MEPT portion of the band (between 10.140000 and 10.140100 Mhz). Output power is about 4 watts, split between both signals.

I’d be interested in any reception reports.

Addendum: Click this link to examine the reception reports I’m getting via the automated WSPR logging.

Addendum2:

Today, on Jan 2, I got a reception report from W1BW, and I could faintly see my “MV” appearing on his grabber:

MV on the W1BW grabber

You can see his “flying W” very strongly, and if you stare really close (click on the smaller image) you can see my MV which looks like part of a sawtooth around 23:22 (and other places).

Addendum2: Alan, VA3STL in Ontario also noticed my signal on the 2nd. Here is his screen grab, showing both my MV and my MEPT signal.

va3stl