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Re: G3RUH Hardware Demod Mk II vs AO40RCV test



Hi All,

Along the lines of comparison between the G3RUH and the ao40rcv (v-0.3) modems.
I tried an experiment this morning that my help us get better at receiving the
AO-40 signal.  The two modems perform about equally well as far as I can tell.
However, they are both sensitive to sudden frequency changes caused by digital
auto tuning.  For the first part of this mornings pass I tuned manually.  My
receiver is an ICOM 275 which has 100 Hz steps.  So, I only tuned *between* data
blocks and let the receiver (doppler) drift while receiving data.  I got nearly
perfect copy.  Of course it was also the very best part of the orbit and I would
have had pretty good copy anyway.  I feel that the between block tuning improved
things a lot.

Moe Wheatley's ao40rcv.exe program has a new provision to do auto tuning via the
handshake lines of a serial port.  I believe it also has a provision to take
advantage of the tuning command timing.  As soon as I have time I will try using
it to tune my receiver.

73's de Rich @ WC8J

----

paul.willmott@omsl.bm wrote:

> http://www.qsl.net/ae4jy/ao40rcv.htm
>
> -----Original Message-----
> From: David Kent [mailto:dak@ioa.com]
> Sent: Monday, January 22, 2001 10:58 AM
> To: paul.willmott@omsl.bm
> Subject: Re: [amsat-bb] G3RUH Hardware Demod Mk II vs AO40RCV test
>
> Paul,
>
> sorry for the intrusion, but I'd be curious to know if the software
> demodulator referred to as AO40RCV is the "French demodulator" or another
> one ? If another where can it be obtained ?
>
> Regards,
>
> David Kent / k4uja
> dak@ioa.com
>
> ----- Original Message -----
> From: <paul.willmott@omsl.bm>
> To: <amsat-bb@AMSAT.Org>
> Sent: January 22, 2001 8:40 AM
> Subject: [amsat-bb] G3RUH Hardware Demod Mk II vs AO40RCV test
>
> > Hi All,
> >
> > This morning I ran both the AO40RCV software demodulator and my G3RUH
> > Hardware demodulator at the same time from the same audio source, .... the
> > hardware won by only 3 CRCC OK blocks!
> >
> > Total scores:
> > AO40RCV: 45 CRCC OK out of 115 received
> > G3RUH: 48 CRCC OK out of 121 received
> >
> > The usual post-perigee pass is good at start, then 2 MAs of spin mod, the
> > good again
> >
> > Both were neck and neck until the 2MAs pf spin mod, ... when the good
> > signals started again the G3RUH was back with CRCC OK, but AO40RCV didn't
> > get any, ... then I went to work so didn't get the end of the pass, ... so
> > this is not a totally conclusive test, ... I would expect DSP to work best
> > under noise conditions, ... like MA20 onwards! That test to come.
> >
> > I was unable to listen passed MA13 because I had to go to work, ... but
> > shows there is very little difference between top end hardware and Moe's
> > AO40RCV software solution.
> >
> > I will continue to test both side by side for a while to see if either one
> > can be optimized either by audio level, audio tone, method of staying on
> > frequency etc.
> >
> > If your software decoder doesn't write log files in the AMSAT Archive
> > format, then try out Moe's program as it is 100% compatible with archive,
> > and works great! You can find the download link on the telemetry page on
> > www.amsat.org
> >
> > Cheers
> > Paul, VP9MU
> >
> >
> > ----
> > Via the amsat-bb mailing list at AMSAT.ORG courtesy of AMSAT-NA.
> > To unsubscribe, send "unsubscribe amsat-bb" to Majordomo@amsat.org
> >
> ----
> Via the amsat-bb mailing list at AMSAT.ORG courtesy of AMSAT-NA.
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----
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