[pskmail] Testing of faster modes

  • From: John Douyere <vk2eta@xxxxxxxxx>
  • To: pskmail@xxxxxxxxxxxxx
  • Date: Mon, 27 Feb 2012 15:04:53 +1100

Dear all,

Having camped in a non-mobile phone reception area for the last 12 days I
had a chance to test some of the faster modes I coded in Fldigi.

I tested the following under NVIS conditions: 400KM strait line, day and
night conditions, 100 watts in a vertical mobile antenna on client side,
G5RV and 50 watts on the server side:

3 x PSK125 (fits in a 500Hz bandwidth and is 50% faster than PSK250).
Result: from these first tests it seems less robust than PSK250 (more so
than expected when taking into account the wider bandwidth).

2 X PSK500R: I am very pleased with that one. Robust and fast (a little
faster than PSK500). Good resistance to NVIS conditions day and night.
1200Hz bandwidth.

3 x PSK500R: also very good although as expected a less sensitive and
robust than 2 x PSK500R. Gives a 55% speed advantage over PSK500. From past
experience I would say around PSK500 in robustness BUT at 1900Hz bandwidth.

I discovered a bug that I need to fix before I release these as the
odd-carrier modes can sometime go completely and stay out of sync: we send
all information twice but don't know where the first bit is in the sequence
of carriers. For even carrier modes this is not an issue of course as we
know the order. This was resolved for the PSKR modes but I have
re-introduced the issue somewhere!

So from these tests I would advance that for HF needs, the multi carrier
raw PSK modes (without FEC) are probably not going to be of much value, but
the PSKR modes will (which is consistent with usual solutions, so no
surprise there).

For FM links, on the other hand, I suspect the multi carrier raw PSK modes
will give good results.

I will now do more tests with the muti carrier PSK250R modes for the US
based Hams on HF bands.

Of interest also I suspect will be the 4PSK and maybe 8PSK modes that I
will test after that, but they will need a better FEC scheme.

I also did some test in portable with the end-fed 41M wire at approx 6
metres above ground (just thrown over tree branches) and the MFSK/THOR
modes: I was getting excellent results right down to 0.5Watts TX on 80M at
night (with plenty of thunderstorm activity around).

I have replaced my LIPO battery with a LI-ION (one of these 9800mAH "blue
bricks" on eBay) for safety and capacity advantage and it delivered many
hours of operation with the FT-817.

So this is definitely confirmed as my portable setup together with the
Android phone and mini Bluetooth audio interface.

All the best,

73, John

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