[amsat-bb] PSAT2 Future Operations

Paul Stoetzer n8hm at arrl.net
Tue Jun 25 22:58:53 UTC 2019


Two questions:

What is the SSTV modulation used?

When PSAT2 is transmitting SSTV, is the PSK31 downlink disabled or is
the FM audio bandwidth shared between PSK31 and SSTV?


Paul, N8HM

On Tue, Jun 25, 2019 at 6:55 PM Robert Bruninga via AMSAT-BB
<amsat-bb at amsat.org> wrote:
> PSAT Voltages look good.
> The PSK31/SSTV downlink appear to be working well on 435.350+/- Doppler,
> But you will only see SSTV during daylight passes (Now occuring in the
> Southern Hemisphere) where the Solar charge voltage is above threshold (6.8
> volts.  THen you should see SSTV images once every 4 minutes automatically
> while in the sun.
> Northern Hemisphere passes are presently occurring overnight and PSAT2 is
> in a 28 degree orbit and not seen at all by high northern latitudes and
> most of Europe :-(
> PSAT2 APRS digipeating will remain off indefinately while all these other
> NEW modes are working.  Do not TX any APRS packets on the uplink.
> DTMF Grid Uplinks-to-APRS/Voice will be enabled LATER.
> While waiting, spend the next day familiarizing yourself with the PSAT2
> APRStt touchtone mode. This mode will let you send DTMF Grid square reports
> which are translated to VOICE and to an APRS packet on the 145.825
> downlink. Be sure to prepare your radio with your pre-programmed DTMF grid
> report IN ADVANCE.  And learn how to send Touchtone from  your radio's DTMF
> memory. quickly!  It should take under 4 seconds.  Do not even think of
> sending it manually.
> Here is WA7MXZ's translator to calculate your onetime DTMF grid report:
> http://aprs.org/aprs_translator.htm
> See how it works in about the middle of the PSAT2 page:
> http://aprs.org/psat2.html
> A successful DTMF uplink will result in a Voice response and an APRS packet
> on the downlink for display on APRS radios.  Again, no APRS Uplink in this
> mode.
> This will be painful because of the 4 second uplink transmissions all
> colliding on the half-duplex uplink, so PLEASE only attempt your DTMF
> uplink once every 30 seconds or longer to give others a chance.  And of
> course NOT while PSAT2 is downlinking.
> We will advise when this mode is enabled.
> http://aprs.org/aprstt.html
> Bob, WB4APR
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