PSAT2 Successfully Launched

This is a summary from ANS-181:

PSAT Successfully Launched on Falcon Heavy STP-2

PSAT2 was successfully Launched at 0630Z on June 25, 2019 on the
Falcon Heavy STP-2 mission into a 28 degree elliptical orbit with
apogee at 860 km and perigee at 300 km. The 28 degree inclination
makes it difficult to work it over most of Europe but the
significant difference in apogee and perigee can make a 15 degree or
so elevation difference on the horizon. When apogee circulates to
be over the northern hemisphere,then more northern stations can
work it. When Perigee is over the
northern hemisphere, it can only be seen in Spain and Italy latitudes
in Europe, and only mid latitudes in the USA.

This changing apogee dynamic will move earlier each day and two weeks
later, will have reversed, and so forth on a monthly cycle or so.
Another interesting thing about the orbit is that it is almost time
synchronous; meaning that a pass will occur almost the same time
every day (though five minutes earlier). But then an earlier orbit
will appear an hour and a half earlier every other day. This makes
it very easy to do mobile/portable operations without any computer
once you hear one pass.

Operating Modes
PSAT2 consists of a number of exciting and unique Amateur Radio
Communications transponders:

  • First is a newer PSK31 29 MHz uplink/UHF FM downlink from Brno
    University following on to the original on PSAT.
  • Second is a Brno SSTV camera that dowlinks in the same UHF FM
    waterfall as the PSK31 users.
  • Third is a DTMF grid square uplink and voice/APRS downlink for
    grid position reporting.
  • Fourth is DTMF Text messaging (APRStt).
  • Fifth is APRS text messages up and voice down.
  • Sixth is a conventional APRS digipeater that will join a number of
    sister APRS Amateur Satellite transponders.

Currently the HF/UHF PSK31 and SSTV modes are enabled and open to
users. But the VHF modes have not been enabled for users and users are
requested to keep the uplink clear during on-orbit testing.

PSAT2 is designed for maximum orbit life compared to other similar
sized cubesats because it is flying with the maxzimum allowable mass.
Almost a kilogram of lead ballast about 2cm x 8cm x 8cm located in the center of the cubesat constitutes almost HALF the satellite’s mass to give it
a high ballistic coefficient to last longer on orbit.

One of the most interesting and unique features of PSAT2 is the new
APRStt (Touchtone) DTMF/voice transponder which lets everyone do APRS
using any radio with DTMF keypad, not just those with APRS radios.
There have been several iterations of the APRStt system in APRS over
the years since 2001, but this application will be new in space and
will help introduce everyone to this unique alternate APRS
capability for use with ANY radio.

Operating Frequencies

  • APRS Up/Down: 145.825 1200 baud APRS (like ISS, PSAT, AISAT-1)
  • DTMF Uplink: 145.980 MHz (Voice confirmation down on 145.825 MHz)
  • PSK31 Downlink: 435.350 MHz ± 5 kHz FM (300 mw)
  • PSK31 Uplink: 29.4815 MHz PSK31 SSB (25 W and omni vertical

PSAT2 Digipeater Aliases
To join the existing APRS satellites on orbit and operate as a
seamless constellation, PSAT2 supports the same APRSAT and ARISS
generic aliases as the original PCSAT (NO44) PSAT and the packet
system on the ISS so that users do not have to change any
parameters when using any of these three APRS transponders.

Complete PSAT-2 information is available at:

The PSAT2 User Manual is available for download at:

[ANS thanks Bob Bruninga, WB4APR for the above information.]


Webmaster and member of the AMSAT-SM steering group.

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