The ARISS S Band
Beacon/Transponder Project
S Band Beacon
• There is a new S Band beacon and
transponder being planned for the ISS-Ham
station. This device is intended to serve as a
beacon for the Ham TV Digital Ham TV system
and also provide the capability of serving as
an FM transponder. This unit will be capable
of serving as an L Band to S band repeater as
well as allowing re transmitting of audio from
other sources onboard the ISS.
Why Do we need this system?
• We need to eventually replace the Ericsson
system with a newer and more powerful
transmitter. The Ericsson only puts out about 5 w
power and that has made the ISS Ham school
contacts more difficult and relegated to the more
sophisticated ground stations. Current plans are
to replace it with a Kenwood D710 mobile
transceiver. This radio needs 13.8 VDC at about
12 amps. The only power supply capable of
providing that power that is currently onboard ISS
is in the Russian module and is not available in
the Columbus module.
Why Do we need this system? Cont.
• The DATV system that was delivered to the ISS in
August 2013 transmits on 2.4 GHz only when the DATV
system is active. When it is running it is transmitting a
digital signal which can only be received with a DVBS
satellite receiver. That signal is difficult to track.
• With the S Band beacon transmitting at the same time
on a different antenna at 2.40015 GHz with a CW
signal, a separate simple receiver can receive the signal
and easily aid in verifying that the ground antenna
systems is tracking the ISS. This will greatly enhance
the probability of success of the DATV project.
Why Do we need this system? Cont.
• The S Band Beacon /Transponder presents the
opportunity to add the capability to include
the ability to transmit the audio signals from
other sources. There are several sources
envisioned for this transmission. The audio
signal from another receiver such as the
Ericsson transceiver, the VC-H1 SSTV system
that is already onboard, or even an L Band
Why Do we need this system? Cont.
• The antennas that are on board the Columbus
module are designed to be dual band. In other
words they can be used to both transmit on S
Band and receive on L Band simultaneously.
We intend to take advantage of that feature
by adding an L Band receiver module that will
provide an audio signal to the S Band
transmitter for re transmitting.
• That will provide an FM transponder function.
What are the tasks that are necessary
to accomplish this?
• The team to develop this system consists of
the ARISS team and Kaiser Italia. The ARISS
team consists of members (Volunteers) from
AMSAT-NA and European ARISS members
from Belgium, UK, Germany, AMSAT IT, AMSAT
France and others yet to be determined.
The Duplexer will be built by AMSAT NA by
George Presley K4RSV.
A proof of concept prototype has been built by George and tests
indicate more than 40 dB separation is easily achieved.
L Band Receiver
The L Band receiver is being designed by David Bowman G0MRF.
Here is the layout he has developed for the L Band receiver.
Block diagram of the S Band
• The S Band beacon and transponder consists
of several components.
• The L/S Band Duplexer, The L Band receiver,
and the Multifunction module.
• The Multifunction module will be built by
Kaiser Italia under contract to ESA.
The Multufunction Module
• The Multifunction module provides several
services .
• The S Band transmitter
• The 13.6 VDC power supply, and the 6.0 VDC
power supply.
• The NTSC Video generator, the CW and
telemetry encoder And the Audio processor
and multi-Power outlets
Modes of Operation
• Current plans call for the system to have several modes
of operation.
• The default mode when powered up will be the CW
Beacon mode. In that mode the system will
continuously transmit a CW beacon that will include
the station call sign and some telemetry such as
temperature or pressure.
• The Second mode will consist of an FM transponder
mode. In this mode the system will send out an S band
FM modulated signal with one of any of three audio
sources selected by the ISS crew.
Preliminary Specifications
• Frequencies: S Band down 2.40015 GHz
L band up 1.2634 GHZ
UHF and VHF uplink depends on the
receiver frequency setting.
• Power output
CW Beacon mode 100mw.
FM Transponder mode 3 w .
Overall Columbus Module Ham Station diagram
What it means for the future
• We will have a ham signal on S band coming down from the
• This will provide a capability to conduct educational and
ham activities on a mostly continuous basis.
• The S Band Beacon/Transponder can be configured in
several ways.
VHF up S Band down,
UHF up and S band down or
L Band up and S Band down.
This can be very exciting for both the Ham and the
Educational community.

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