Here's a brief update for those who may not be active on the VHF bands
or otherwise following the development of QRA64 and MSK144.
QRA64A QSOs are being made nightly on 160 m, of all places; and QRA64
activity on 2m EME is becoming significant, especially on weekends.
Last Friday evening I pointed my 4-yagi array at the Moon and called CQ
on 144.118. The moon had already set in EU, but in quick succession I
worked K5DOG, K1SCE, K2ZJ, K9SLQ, and KK6FAH, all in less than an hour.
On Saturday evening I started CQing a bit earlier and worked K9SLQ,
EA3CYQ, G4URT, SM4GCC, K0TPP, KF8MY, SP8NR, K8MRI, AA5IT, and KD7UO.
This in less than 2 hours, with time out for dinner in the middle.
There are some pretty small stations in this group, e.g., a few hundred
watts and two yagis. As expected from our simulation measurements,
QRA64 is decoding signals down to about S/N = -28 dB.
So QRA64 is working well! At present the decoder is made to concentrate
on one signal at a time. It does not yet have some of the nice features
of JT65, developed over some 14 years, that allow decoding of many
signals in the same passband, automatic suppression of birdies, dealing
effectively with drifting and overlapping signals, etc. But these
things will be built in, over time, as we gain more experience with
QRA64 signals.
The biggest boost to use of QRA64 for EME on 2m and higher bands will
probably occur when I find time to build a QRA64 decoder into MAP65.
That big project has not been started, yet; but over the weekend I did
save a handful of MAP65's *.tf2 files to be used for this purpose.
Big thanks once again, to Nico, IV3NWV, for his pioneering work on QRA64!
Meanwhile, MSK144 is quickly becoming *the* mode for meteor scatter,
at least in NA and EU. At most times there are now 50 to 100 stations
sending 50 MHz MSK144 "spots" to PSKReporter site, revealing plenty of
activity throughout these regions. Unlike FSK441 (the older standard
mode for meteor scatter), MSK144 uses strong error correction and
JT65-like messages. Messages are displayed in complete form or not at
all, and false decodes are rare. Last week we introduced an "SWL"
feature that allows decoding of MSK144 "Sh" (short) messages directed to
someone other than yourself. Sh messages are intended for use on 144
MHz and higher frequencies, where pings are much shorter than on 6m.
Steve, K9AN, deserves most of the credit for design and implementation
of MSK144.
Finally, I will mention a new "FreqCal" mode being implemented in
WSJT-X. This mode is designed to achieve frequency calibration of your
radio in a semi-automated way, producing accurate values for the
constants "Intercept" and "Slope" on the WSJT-X *settings ->
Frequencies* tab. These tools make it possible to "know where you are"
to +/- 1 Hz accuracy, or better, and to measure the frequency of other
signals to similar accuracy. Instructions for use of the FreqCal mode
will be forthcoming soon.
-- 73, Joe, K1JT
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