WSPRs and Wet Strings.

Amateur radio is a hobby that attracts the curious and, in general, well-educated.

It's also a hobby that attracts stubborn men, who prefer Donald Trump-esque fixed ideas, rather than open their minds to the complexity of life.

A good antenna?  Hardly.  Image: Wikicommons/Nevit Dilmen.

I often hear operators - and I'm afraid they are usually American - claim that, because WSPR signals can be heard by "any old wet string", the propagation and antenna tests we run are of no real-world significance, because we "would never get a QSO in other modes".

As soon as I hear this kind of thing, I know it's time to stop trying to contribute to anything like an informed debate.

Yesterday, the weakest spot I received was -33dB on WSPR, using 200mW.  That's about as low as WSPR can get. Of course, the question why that spot was -33dB can have many different answers.

It could be an operator with a very noisy environment.  He could have a rubbish receive antenna.  My signal could be very weak.  It could be a transient propagation enhancement.  It could be a high angle signal when the antenna favours low angle.  Lots of things it could be.

WSPR: it's not 'fake news', folks.  Image: Wikicommons/By Gage Skidmore from Peoria, AZ, USA.

Reasons aside, the claim remains that someone hearing a WSPR signal will not hear other modes.

This is all very odd, because JT65 is meant to reach down to about -24dB before reaching a 50% error rate, and JT9 down to about -26dB.  The fact that there is a certain error rate creeping in does not, of course, mean that we won't decode a weaker signal and, indeed, we all do receive weaker ones regularly.

The software in use also makes a difference.  JTDX, from practical experience, clearly decodes weak signals much more effectively than the original WSJT-X software.  One hardly ever sees multiple, overlaid decodes, often differing by 20dB or more, using WSJT-X, whereas they are rather common with JTDX.  Accordingly, JTDX can probably reach reliable decodes at a significantly weaker S/N than expected under the native software.

There are three things the stubborn old men fail to understand:

(1) Many modern weak signal QSO modes are entirely capable of hearing and decoding at the same approximate level, and therefore out to much the same DX distances, that the WSPR mode attains.  There is no drastic difference in each mode's capability by now.

(2) Many WSPR operators, pushed by the likes of WSPRlite transmitters, are now settling on QRPp outputs of 200mW or less.  This output level is usually much lower than the power operators will use for 'real QSO' modes like JT65 and JT9, where 5-10W is the norm.  As a result, if someone is hearing you with 200mW WSPR, there is little question they will hear you with 10W JT65A, even if we allow for the somewhat lesser sensitivity of the latter mode.  Even OLIVIA, which has a nominal sensitivity limit, probably exceeded in practice, of -14dB S/N.  This sometimes has the unnerving effect of having a near copy-perfect QSO when no signal is visible on-screen!

(3) One should spend a lot of time carefully experimenting, rather than adopting an opinion that has no basis in evidence.

So, if you hear that old 'wet string' thing again, just turn the other way.  No amount of evidence will sway the Trump-esque amongst us!