[IRCA] Don't forget your best het locater, the sound card

["Don Moman" <ve6jy@xxxxxxxx>]

Nick's comments below prompted me to remind myself just how useful the sound
card (in your computer) can be in all of this detective work.....


>
> > saunter, don't rush,  over to your receiver....1314 has been slowly
> > gathering strength over the last hour, now (0230UT) a generally good
> > carrier.   1215 showing signs occasionally, and just the merest wisps on
> > 1134, 1422 and 1575....in fact, wishful thinking type carriers on
several
> > other frequencies in the splash...
> >
> > Still, promising.  Don't go to bed just yet.
> >
> > best wishes,
> >
> > Nick
> >
>


I was hearing so many hets tonite that I had to find some of my old "Foreign
Broadcast Activity Charts"  and annotate them  (Nick and others, now that
brings back memories..... Cardinal Divide, Pembina Forks, 7 Mile Flats etc).

One hates to waste a "lot" of time in chasing hets especially if you're
missing the few that have turned into audio while you're trying to decide if
that was really a het or not.  This is what works best for me - I just set
the fast SSB tuning step to 9 khz and make sure the radio is started 1 khz
off of the standard 9k split.  The radio here is the ICOM 756PROIII, and I
normally just use the slow rate of 10 hz, but momentarily pushing the TS
button puts you into fast - which is now set to 9khz steps.   If I tune up
from the bottom of the band I'd use USB and start 1 khz low.  This produces
a 1khz beat note that is readily viewed using your computers sound card and
any one of a number of free audio spectrum analyzer programs out there.  I
happen to like Spectran by IK2PHD and IK2CZL. A small download, just use
google to find it.

You can use any offset you like, just that 1 khz is an nice even number for
the next step.

The steady 1 khz het will be easily visible in many cases even when covered
by splash.  If your sound card (and radio) are accurately calibrated you can
measure the stations carrier frequency easily to at least 1 hz resolution,
and without ANY test equipment.  We do cheat a bit and use the tones that
WWV transmits in case you were wondering.  Just tune in the 500 khz tone  -
first in AM to verify your sound cards accuracy, then in SSB to determine
how far your radio is off.  Then either calibrate your radio or do the
necessary math....  My old sound card (5 yrs old with a slow PII-400
computer) is around 0.1 hz off or less.  And the ICOM can be calibrated to
about 1 hz before the control gets too finicky.

Another neat feature is the ability to see multiple carriers. For example,
855 had 3 carriers, 1 dominant and 2 much weaker 20 minutes ago, now there
is only 2.  If we had a database of precise carrier frequencies we could
even make an educated guess to who generated them.  This could be equally
useful on domestic channels too.

A quick scan - every 9 khz split - of the band was completed in around 5
minutes, which included making notes. No TA was of audio level now, but 44
channels were easily noted as having hets.  1314 had the best with a carrier
rising about 20db above the noise.

73 Don
VE6JY

Don Moman, near Edmonton Alberta CANADA
ICOM 756PROIII,  beverages

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