[amsat-bb] PSAT PSK31 experimental software

Thu Jul 16 22:20:38 UTC 2015

What is the station equipment, antennas etc.
Joe WB9SBD
Sig
The Original Rolling Ball Clock
Idle Tyme
Idle-Tyme.com
http://www.idle-tyme.com
On 7/16/2015 2:57 PM, David W0DHB wrote:
> Andy
>
> Here is a recording of the 1930 pass of NO-84
> https://www.dropbox.com/s/2qtb5d2cm3ktrr0/FM%20435.359944MHz%20%5B12k%5D%207
> -16-2015%2019%2033%2052.wav?dl=0
>
> Bob KO6TZ and I had a successful QSO. My audio was set at 1500 Uplink
> frequency  of 28.119700 MHz .
>
> The signals seemed to be stable, decoding at my end (DM780 ) was not
> stellar, I'm running the recording through fldigi, MixW and Digipan to see
> if it's any better.
>
> Dave W0DHB
>
> -----Original Message-----
> From: AMSAT-BB [mailto:amsat-bb-bounces at amsat.org] On Behalf Of David W0DHB
> Sent: Thursday, July 16, 2015 8:41 AM
> To: 'aflowers at frontiernet.net'; amsat-bb at amsat.org
> Subject: Re: [amsat-bb] PSAT PSK31 experimental software
>
> Hey Andy
>
> The ability to select soundcard would be helpful. In my setup TX audio is
> fed by a virtual audio cable set to match the 48K sample rate that
> DopplerPSK is using.
> Folks using windows should set the recording device side of their soundcard
> to a 48K sample rate (it usually defaults to 44.1K).
>
> You are correct that the uplink frequency is high, I apply a -300 Hz
> calibration offset.
>
> Thanks for all your work on this.
>
> Dave W0DHB
>
> -----Original Message-----
> From: AMSAT-BB [mailto:amsat-bb-bounces at amsat.org] On Behalf Of
> aflowers at frontiernet.net
> Sent: Thursday, July 16, 2015 6:29 AM
> To: amsat-bb at amsat.org
> Subject: Re: [amsat-bb] PSAT PSK31 experimental software
>
> Bob, Dave;
> That's great.  I'm interested in how well it tracks when the satellite is at
> a very high elevation and the Doppler is >3 Hz/s.  I suspect the error is
> going to be mostly in the estimates of the orbital elements, but we'll see.
> I will try to join you on the pass when I can cobble together an uplink and
> a downlink in the same place--probably next week sometime after I get back
> from vacation.
>
> I think you should be able to share a sound device on most OS's, but I have
> not tried.  I assumed it would work on modern Windows OS's because of the
> hardware abstraction.  The program appears to run fine on OSX, but I have
> not tried running CocoaModem or some other software next to it.  Ultimately
> I could also add a demodulator to the program itself, but that will take
> some work....I know several hams have separate sound cards for radio stuff,
> so I may need to add a device selection option in case the system default
> (or whatever Java picks as the default) isn't what you want.
>
> The audio frequency displayed in DopplerPSK is the audio frequency being
> send to the radio, not what you should expect in the passband of your
> downlink receiver. The LO on PSAT is apparently a bit below 28120 KHz, so if
> your radio was tuned to 28120 USB (suppressed carrier frequency) you would
> expect to be a bit higher than 2000Hz in the FM passband:
>
> http://www.urel.feec.vutbr.cz/esl/files/Projects/PSAT/P%20sat%20transponder%
> 20WEB%20spec02.htm
>
> In general, if you want to be lower in the passband I would lower your
> transmitter RF frequency rather than the audio frequency going to the
> transmitter.  The reason being that if you have any non-linearity in the
> audio chain you don't end up transmitting a harmonic higher in the band that
> might bother someone else.  Of course, you can probably see if this is an
> issue or not since the satellite also serves as a crude signal analyzer :-)
> I chose 2000 Hz as a center since at maximum Doppler of around 700 Hz, the
> ~2700 Hz tone should go through the transmitter's IF filter without too much
> attenuation while keeping all the third harmonics and most of the time the
> second harmonic above the cutoff of a 3 KHz IF filter.  Every radio is a bit
> different, however.  You may find that the 1500Hz sweep in the program shows
> you all your passband ripple in your IF filter :-)
>
> Since it works, I'm more motivated to improve the ergonomics of the
> interface.  Much of that depends on the unique operating practices of
> satellite operation.
>
> Andy K0SM/2
>
>
>
>
>   On Thursday, July 16, 2015 12:31 AM, KO6TZ Bob <my.callsign at verizon.net>
> wrote:
>   
>
> The software worked great !!!  Produced a straight line on the waterfall for
> the down link.
>
> As expected, I was alone on the pass, so no opportunity for a contact.
>
> I was using digi-pan for the RX, my signal was at around 2200Hz..
> Probably an indication the oscillator in my radio is off a bit.  I think I
> will lower the frequency from 2000 to about 1600.  That will put my signal
> lower in the VF pass band.
>
> I like the program.  Had good copy.
>
> THANKS.....
>
>
> BOB  KO6TZ
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> _______________________________________________
> Sent via AMSAT-BB at amsat.org. AMSAT-NA makes this open forum available
> to all interested persons worldwide without requiring membership. Opinions expressed
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