[PCR-1000] packet output

Thu, 30 Jan 2003 23:58:28 -0000

Hi Patrik,
I have seen this mod before and have always thought it a little dangerous
for questionable gain.  However, this discussion has left me with no moral
choice :) !!

I performed the mod (its not too tricky after all) and results are
interesting.  I havn't taken any "scientific" comparative measurements yet,
but it is obvious that the discriminator output is considerably better than
the speaker output, allowing WxSat to lock and decode at much lower signal
levels (ie worse noise).

I still don't really understand why the difference should be so great and I
would be grateful for any explanation.  I'm beginning to think that its not
so much about high frequency cutoff (which is obvious by listening to the
two outputs via computer), but more about phase delay and possibly _low_
frequency response - investigation tells me the NOAA siganls are not simply
FM modulated with 2400 baud data: the modulating siganl is itself AM
modulated with the telemetry data - and I reckon thats where the low freq
components are.  Anyone care to add to the theory or point me to a useful
website (putmeoutofmymisery.com ?).

Interestingly, I have tried the discriminator output with ACARS and results
seem to be worse than speaker o/p at first trial - less messages decoded,
although a fairly short test.

Further, can anyone with a pcr1000 tell me what speech sounds like from
their packet output - I need a sanity check on my mod.

Thanks again Patrik for getting me into this - I think there will  be much
to be gained in some areas.  If this mod represents the packet output on a
pcr1000 then I would strongly recommend that enthusiasts should use the
packet output for NOAA for a lower threshold.

Brian

----- Original Message -----
From: "Patrik Norqvist" <[email protected]>
To: <[email protected]>
Sent: Wednesday, January 29, 2003 10:09 PM
Subject: Re: [PCR-1000] packet output

> At 21:30 2003-01-29 +0000, Brian Winter wrote:
>
> >I have a PCR100 (ie with no packet output) currently dedicated to
satellite
> >stuff - time to experiment with that and possibly reconsider equipment
usage
> >I suppose.  I am particularly impressed at the report of horizon to
horizon
> >coverage.  Now that really would be worth having.
>
> This link may interest you:
>
> http://www.webdeals.net/100mod.htm
>
> Regards
>     /Patrik
>