[amsat-bb] A suggestion for Experimenter's Wednesdays on (PSAT?)

Robert Bruninga bruninga at usna.edu
Fri Dec 15 14:50:42 UTC 2017

An Experiment I would like to see done is experimental DATA and RTTY modes
on PSAT's PSK31 Linear transponder.  I rarely hear anyone using PSK31 and so
it is quite available.  It has a linear receiver for any modulation going up
on 28.120 MHz and then the demodulated audio comes down on FM on UHF 435.350

But the uplink is SHARED with terrestrial RTTY and DATA modes (though very
rarely are there signals there)...

The only catch is that there does need to be at least one PSK31 signal in
the passband to cause the transponder to come up.  But once up, it is a
clean bent pipe for all the rest of the 3 KHz bandwidth.

I read Part 97.307(f)4 and 309(a) as saying any digital mode that is less
than 1 Khz FSK or under 1200 baud symbol rate can be used?

One other catch. (my fault)... It Recycles every 20 seconds.  Which means
the carrier will drop for a few seconds as the processor is reset and then
it waits for the 31 Hz detect to come up again.  So time your exchanges in
the 20 second repeating windows...


-----Original Message-----
From: AMSAT-BB [ On Behalf Of E.Mike McCardel
Subject: Re: [amsat-bb] A suggestion for Experimenter's Wednesdays on AO-91

It seems to me that the limiting factor for using LEO satellites as an
Emergency Response of any scale, would the short amount of time of a given
pass and the limited number of usable passes a day over an area needing the
response. I’m not sure experimentation would find ways around this
limitation. But of course experimentation is just that.

Perhaps we need to get out of the box for how Experimenter’s Wednesdays
work. What modes can we adapt? Can we incorporate an educational initiative,
similar to ISS school contacts? Remote control APRS messaging as Mark
Spencer demonstrated with MAREA? I know these seem like we are limiting
contacts to just a few people, but they can reach hundreds of students and
introduce satellite and radio enthusiasm to another generation of school
children and millennial.


EMike McCardel, AA8EM
Rotating Editor AMSAT News Service
Sent from my iPhone

> On Dec 15, 2017, at 1:26 AM, Mac A. Cody <maccody at att.net> wrote:
> I'm embarrassed to say that I've never done anything personally with
> NBEMS.  What I knowabout it isfrom a presentation at my radio club.
> We have had a group that was experimenting with NBEMS on the club
> repeater.  Don't know whether they are still doing it, though.  They
> weren't using any special interface between radios and computers -
> speaker output to microphone input in both directions.  I'd like to
> try NBEMS on the FM birds simply as a way of experimenting with using LEO
> birds for emergency response.
> As you mentioned, there is a lot of sites out there describing how to
> use NBEMS using Fldigi/Flmsg.  I have not seen anything specific, yet,
> regarding to using NBEMS over a satellite.  I'm sure that there are
> attendant challenges and opportunities doing so.
> Doppler shift and signal quality will be the main challenges. MT65
> appears to be the modulation scheme of choice.  Full duplex operation
> would be helpful, as you could monitor your own signal to verify its
> quality and how well the message got through.
> I'll have to investigate further.
> Mac Cody - AE5PH
>> On 12/14/2017 11:38 PM, Scott wrote:
>> I've always been curious about NBEMS as well, Mac.
>> There is a fair amount of info on the subject online, but could you point
>> me to any particular orientation how-to that might be geared to someone
>> using it in a more informal setting such as how we might use it via an FM
>> satellite?
>> -Scott,  K4KDR
>> -----Original Message----- From: Patrick STODDARD (WD9EWK/VA7EWK)
>> Sent: Friday, December 15, 2017 12:29 AM
>> Subject: Re: [amsat-bb]  Experimenter's Wednesdays on >> AO-91
>> Now that's a good idea. Otherwise, Wednesdays on AO-85 could be
>> called SSTV Wednesdays, if that's the extent of "Experimenter's
>> Wednesdays" for that satellite. I would be inclined to try NBEMS,
>> something I've never used.
>> Patrick WD9EWK/VA7EWK

>>> On Thursday, December 14, 2017, Mac A. Cody <maccody at att.net> wrote:
>>> If, as you stated, SSTV has run its course, maybe Experimenter's
>>> Wednesdays on AO-85 could be changed to experiment with EMCOMM using
>>> NBEMS, thereby keeping AO-91 as free as possible.  Once that has run
>>> its course, then move on to another experiment. That would keep
>>> things fresh.  I think a report on each experiment would be an
>>> interesting series of articles in the AMSAT Journal.  I think
>>> continuous experimentation is a good thing!
>>> Mac Cody - AE5PH

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