WSPR problems at 28 MHz...

WSPR - Weak Signal Propagation Reporter. I have been monitoring the WSPR frequency on 28 MHz recently as the conditions have been really good and there are now a good number of stations mostly from the northern half of Europe transmitting on the band.

There are a few important issues that you must be aware of when you transmit a signal on WSPR.

1. Timing... Regardless of the band, your time on your PC must be spot on. I've seen examples where people are transmitting tens of seconds too late!  This is an example of people just letting their WSPR transmitters on without checking if it is working ok.

WSPR transmission outside the two minute window marked by the Green lines

2. Frequency... On the lower bands like say 80m or 40m, transmitters drift a lot less. On 10m, the frequency accuracy and drift becomes a bigger issue.

This is an example from the WSJT-X waterfall of someone way off frequency....

This WSPR frequency on 10 metres is 28.1246 MHz and the band is just 200 Hz wide i.e. audio frequencies of 1400 to 1600 Hz.

As you can see from the screenshot above, someone was about 230 Hz too low and no-one is ever going to decode them.

3) Drift... For the two minute WSPR transmission, the signal shouldn't drift by more than 4 Hz.

This image above shows the frequency of the WSPR signals plotted against time. The signals in the top half of the image show normal WSPR signals which are two minutes in duration. As can be seen, they are nice and straight.

In the lower part of the image, there is an example of a drifting WSPR signal. Over the two minutes, it drifts in the region of 15 Hz, way too much to be ever decoded.

If you're on WSPR on 28 MHz and you're not being heard then look at your time, frequency and drift.