[time-nuts] ARRL FMT results

[James Maynard]

Rex wrote:

I didn't play in this game so I haven't been paying close attention to
the contest or results. In my skimming of the messages I think I am
hearing that several knowledgeable people came out with results close to
each other but offset from the "winning" results.

If I am correct in my assessment, seems like the ARRL should be made
aware that the process or the specification of the contest signal may be
lacking in some details.

What do you think was the issue? Was it a modulated carrier on SSB with
some residual rather than pure CW?

If there is some consensus of close mis-measured results in this group,
seems like the ARRL needs to be informed about it so exactly what the
signal is  is described or the contest is modified with a better pure CW
carrier in the future.

Am I right, or am I completely missing the point in some way?

-Rex

I think it is interesting that our measurements of the received W1AW 
signal in the 40-metre band differed by about 1 Hz from the ARRL 
measurement of the transmitted signal.  However, I would not necessarily 
attribute the difference to measurement errors at W1AW. The received 
frequency will differ from the transmitted frequency because of the 
changing path length as the signal is propagated via one or multiple 
reflections from a moving ionosphere.

Here on the west coast, my measurement of the received signal frequency 
differed from W1AW's measurement of the transmitted signal frequency by 
a mean of +1.4 Hz and a standard deviation of +/- 9.4 Hz.  For me, 
W1AW's signal was very weak - inaudible, visible only as a very smeared 
trace on a SpectrumLab waterfall display.  And, juding by the 
comparatively large standard deviation of my measurements, the received 
signal was *severely* affected by multipath and ionospheric doppler.

I would attribute the difference between our measurements of the 
received signal and W1AW's measurement of the transmitted signal, not to 
measurement errors on the part of the W1AW staff, but to corruption of 
the signal en-route from Connecticut to our respective locations.

I am puzzled as to why our measurements of the received 40-metre signal 
were consistently higher than W1Aw's measurement of the transmitted 
signal. I would have expected ionospheric doppler at that time of day to 
cause the received signal to be lower in frequency than the transmitted 
frequency, rather than higher.

But that may be a misunderstanding of just what was happening. It might 
be a combination of a rising ionosphering F-layer and a forming E-layer 
at a lower height. The forming E-layer would have an effect of 
decreasing the average path length (increasing received frequency), 
while the rising F-layer would have an effect of increasing the path 
length (lowering the received frequency) for that part of the signal 
that was received by the F-layer.

--
James Maynard, K7KK
Salem, Oregon, USA