JT65/JT9 not impervious to false positives…
I haven’t had a lot of time to operate JT65/JT9, my preferred digital mode at the moment, but I often leave my receiver hooked up and monitoring the bands for reception reports. My wet-noodle of an antenna can usually pull in signals from about 40 different counties in the span of a week of monitoring. I usually leave it running on 40m during the night, and 20m during the day. Sometimes I’ll toss in 15m just to see what’s going on. Here’s a screengrab of the last 24 hours, for instance:
If you want, you can go to the PSKReporter website and enter my callsign K6HX (or any other) and get a live report. In this map, the blue dots are signals that I received on 40m, the yellow ones are 20m, and the brownish ones are for 15m. If you look at these regularly, and over time, you can begin to get some idea of how propagation works by frequency and by time of day.
But look at that map closely, in particularly in the area up above Scandanavia, you should see a single yellow mark well above the Artic circle. A little poking indicates that this was for the rather unusual callsign JW4BHO, which comes from Svalbard. I’d never seen a radio spot from there, which is always exciting. I looked up JW4BHO on the callsign database on QRZ.com, and I felt a bit sadder. His callsign wasn’t registered: not a good sign. I also did a db search on PSKReporter to see if anyone else had spotted him. No one else had. Rats.
One thing bothered me though: the callsign and the marked for the reception report matched. JT65/JT9 signals both encode the Maidenhead gridsquare to indicate the position of the transmitter. If this was just random noise, then how did the location and the callsign match? That seemed very unlikely by chance.
Luckily, I still had WSJT-X up, and could scroll back and look at the reception report:
Here you can see that WSJT-X reported a signal from JW4BHO to T07NAA from gridsquare OQ65, at a SNR of just -17. -17 isn’t a particularly weak signal, which surprised me a little, but the reception report is obviously bogus. T07 doesn’t even refer to a valid country. But somewhat oddly, the gridsquare OQ65 isn’t even the gridsquare marked on the map. For some reason, the PSKReporter website has decided to substitute a generic square marking the center of the country instead of using the actual gridsquare marked in the reception report. That seems odd to me.
And this isn’t the first time it happened to me, I’ve seen it a couple of times over the last month, including a fictious spot from Somalia.
Has anyone else had this problem?