[RTTY] ARRL.org Vote - We Need to Become More Pro-active

[Kok Chen]

<w7ti@dslextreme.com> wrote:

> Don's comments are right on, as usual.  I would love to experiment with
> PSK31 in a high power, narrow bandwidth configuration, but to do that in
> the existing segment would bring down the wrath of everyone there.

I don't think you have to run a kilowatt.  You just need to be
3 dB above the other guys.  Considering most of them run a dipole,
Bill just needs to use 10 watts to be loud.  Hee hee.

I often run 80 watts.  If you keep the signal clean, I think you
will be OK.  I try and keep the ALC somewhat lower than recommended
by the rig's manual.  One of these days, I will actually take time
to sweep the spectrum with another receiver to find the optimal ALC
point for my rig.

<rant>
The main problem with running power is that these $#%#* (just a
little short from calling them idiots) QRP guys don't understand
the finite dynamic range of A/D converters.  A very loud signal
could AGC the receiver to the point the small signal is drowned
out in the IMD of the A/D converter in their DSP, even if the loud
PSK signal is perfectly clean.

It is their own bloody fault for not using narrow filters, opting
instead for the armchair-like operation of clicking on barn
door-wide waterfalls.

Most of the PSK implementations I have seen also make use of table
lookup 16-bit FIR filters with integer coefficients.  A loud signal
will render a small signal completely useless through one of these
FIR filters.  Again, it is not the fault of the fellow using high
power, it is the fault of the implementation of the PSK demodulator.

Depending upon the DSP to do all the filtering is a fallacy.  Until
A/D converters have 120 to 140 dB of dynamic range, and algorithms
are run with 32 bits of arithmetic, you will always need a good
analog filter in front of the DSP.
</rant>

All that fuming aside... PSK is a nice mode until you encounter
flutter.  Flutter that still allows you to print FSK painlessly
can cause no print on PSK.  Phase gets all messed up.

There are lots of new comers in PSK31, and they are not afraid to
experiment.  About a month ago, I answered a CQ from an HL station.
Turned out it was his first ever PSK QSO.  So, I sent him a direct
QSL card to commemorate the event, and received a reply in the mail
yesterday.  This chap is no new ham.  He was in fact at one time
a division director at the KARL.

I would also not be very surprised if many PSK31 ops are ones who
live where it is not practical to run power, or even a visible antenna.
As such, it is giving more people the chance of getting on the air,
and in a digital mode at that.

It is also good that the myth that "CW can get through when other
modes don't" is now more universally rejected.  Those of us who'd
studied OOK versus PSK/FSK knew that all along. (I am still against
the use of spread spectrum on the HF bands, however.  But if others
do it, I will too; it will get through when PSK31 can't, HI)

73
Chen, W7AY