HeidelSat Ground Station for GENSO Network - SRH Hochschule ...

HeidelSat Ground Station for GENSO Network
Achim Gottscheber
School of Engineering and Architecture
SRH University of Applied Sciences Heidelberg
Heidelberg, Germany
achim.gottscheber@fh-heidelberg.de
Abstract—First test results with the GENSO network are shown
in this paper. It also describes the architecture of the HeidelSat
ground station, that is connected to the GENSO network.
Keywords: GENSO, ground station, amateur radio
frequencies, CubeSat
I.INTRODUCTION
The International Telecommunication Union (ITU)[1] is an
agency of the United Nations which regulates information and
communication technology issues and coordinates the shared
global use of the radio spectrum. Amateur Radio participation
[2] in space research and communication is restricted to
certain frequencies. The usage of these frequencies is free of
charge, however, the operator of such frequencies needs to
have an amateur radio license. An amateur radio satellite
frequency allocation is done by the International Radio
Amateur Union (IARU)[3].
In 1999, a so called CubeSat[4] standard for pico satellite was
initiated by California Polytechnic State University and
Stanford University. It is recommended that such CubeSats
should be no longer in space that 25 years.
Therefore, only low earth orbits (LEO) [5] are of interest in
this respect. The time a Satellites needs to travel in an
LEO,around the earth is about 90 minutes, and it can be
continuously seen by a ground station for about 10 minutes or
less in one circle around the earth.
In order to have more often contact to a CubeSat in LEO, it is
desired to have a network of many ground stations that are
distributed around the earth in order to increase the average
reception time per day for CubeSats.
This was the reason to initiate a so-called GENSO[6] network
of ground stations in 2006, that can interact via a software
standard. A GENSO ground station is currently designed for
the 70cm and 2m amateur radio frequency band. However, it
is planned to extend this also to other frequency bands, e.g.
13cm band.
II.HEIDELSAT GROUND STATION
In 2006, a ground station for amateur radio frequencies (2m,
70cm, 23cm, 13cm) was started to be build, see picture 1.
Its name is HeidelSat and its call-sign is DN1FHH. The
ground station has three antennas, i.e. a parabolic antenna with
a diameter of 3,65m and two cross-yagi antennas. The
parabolic antenna has a multi feed for the 13cm, 23cm and
70cm band. The cross-yagi antennas are for the 70cm and 2m
band. So far, only the 2m and 70cm cross-yagi antennas are
Mathieu Chadelas
Opto-Electronic and Hyper-Frequencies
University of Montpellier 2
Montpellier, France
cyrain800@hotmail.com
used for the GENSO network. The parabolic antenna is used
to directly communicate with satellites using amateur radio
frequencies.
Picture 1 : HeidelSat ground station
II.1 MATHEMATICAL COORDINATES FOR THE MOVEMENT OF
THE ANTENNAS
Elevation and azimuth are measured with a rotary encoder
sensor to get the coordinates of the antennas, compare
picture 2.
1

Picture 2 : Coordinate system for elevation and azimuth
It is possible to move the antenna manually or via a satellite
tracking program or switch to predefined positions like the
parking position or maintenance positions. There are two
devices between the computer and the two rotors for
controlling the position of the antennas.
1) A unit counter[7]
2) A control unit
II. 2 HARDWARE FOR CONTROLLING THE ANTENNAS
The unit counter, in picture 3, and the control unit, in picture
4, are described in this section. A unit counter is used as a
sensor to set the position of the antennas. It has the function of
a dual counter and a rate meter.
Picture 3 : Unit counter
There are three rows on the left of the display shown in picture
3. In row one, there is letter A. In row two, there is letter B. In
row three, there is letter C. Each letter represent on counter.
Letter «A» is dedicated to the azimuth and letter «B» to the
elevation. The third counter is not used. Each counter needs an
upper and lower coordinate limit. The maximum precision is
0.5 degree. The counter communicates via RS232, having
9600baud.
A Control unit has been build to be able to switch
between four different operating modes.
Picture 4 : The control unit
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In the first mode, signals arrive from an analog remote control.
The second mode is for computer control, the third one is for
parking position, and the fourth for five different maintenance
operations.
The parking position is necessary for stormy weather
conditions.
II.3 LIGHTNING PROTECTION
To protect the ground station from lightning strokes, the
ground station is using three coaxial fuses. They are specified
for a certain bandwidth and impedance. This protection has
been implemented to increase the safety of the ground station.
In addition, four interconnected ground rods are placed near
by the antennas.
The primary purpose of the external ground rods system is to
disperse as much of the lightning energy as possible into the
earth before it might follow the feed line into the ground
station. The ground rods are visible in picture 1.
II.4 GROUND STATION SOFTWARE
A) SATELLITE RECEPTION SOFTWARE
Ham Radio Deluxe (HRD) is a CAT control program
providing computer control for commonly used transceivers
and receivers. HRD also includes mapping, satellite tracking
and the digital mode program Digital Master 780 (DM780).
The Sat Track program adds satellite tracking capabilities to
the Ham Radio Deluxe suite of programs. Its key features
include:
- Providing information about when satellites will be within
range.
- Controlling the transceivers, setting frequencies and
compensating for doppler shift.
- Controlling the rotators so that the antennas can track 17
satellites.
Picture 5 : HAM Radio Deluxe
Figure 3.4.1 HAM Radio Deluxe
HRD, shown in picture 5, is used to configure the transceiver
(ICOM IC-910H) for HeidelSat Ground Station, in respect to
At HeidelSat Ground Station, we use HRD to configure our transceiver (Icom 910H) to
GENSO.
be able to communicate with other ground stations with the use of HeidelSat call signal
(DN1FHH).
MixW, shown in picture 6, is a multi mode, multi functional
HRD is designed for Windows 2000 or higher (XP, Vista, 7), also Internet Explorer 6.0
(or software. higher) is required. It supports The installation the modes of this : program CW, BPSK31, is quite simple QPSK31,
but it requires at
least some of minimum computer specifications which are:
BPSK63 & 125, MFSK, RTTY, FSK31, Packet (HF and VHF
including TCP/IP over AX25), Pactor RX/TX (TX requires
� HRD: 500MHz CPU, 512MB RAM and 20MB of disk storage.
� DM780: 1GHz CPU, 1024MB RAM and 50MB storage (or more if using SSTV).
DM780 uses more resources than HRD when decoding many signals
simultaneously.
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3.4.2
MixW
MixW is a multi mode multi functional software which can be used in many features.
MixW supports many modes like CW, BPSK31, QPSK31, BPSK63 & 125, MFSK,
RTTY, FSK31, Packet (HF and VHF including TCP/IP over AX25), Pactor RX/TX (TX
TNC), Amtor (Sitor) TX/RX (No TNC needed), Hellschreiber,
requires TNC), Amtor (Sitor) TX/RX (No TNC needed), Hellschreiber, FAX (RX only),
FAX (RX only), SSTV, THROB, and MT63 [8][9]. In addition
SSTV, THROB, and MT63. In addition to these built-in modes, new modes can be
added to these to MixW built-in using a modes, facility called new "External modes mode can plugin be support". added to (Ref MixW 7)
using a facility called "External mode plugin support". MixW
MixW does does not not need require a TNC a TNC to operate. operate, The it only needs requirement a computer is that you with have a
computer running Windows 9x, ME, NT, 2000, or XP operating system, and a
compatible sound-card and one of the RigExpert USB
compatible soundcard and one of the RigExpert USB interfaces. And it also allows using
TCP/IP interfaces. connection It allows over AX.25 TCP/IP packet radio connection protocol. via AX.25 packet radio
protocol.
3.4.3
PAXON
Paxon is a software used in telemetry decoding that allows us to configure our TNC7
Multi and choose the proper modulation technique for communications. There is a wide
range of modulation techniques from which we can choose. For example, to use
9600bps Picture FSK 6 : KISS/SMACK MixW Software mode, all we have to do is to switch the TNC7multi to
position 9k6.
Figure 3.4.2 MixW Software
Paxon is a software used for telemetry decoding and allows to
[SRH Paxon University is a very of Applied suitable Science Packet Heidelberg Radio | Ludwig-Guttmann-Strasse terminal program which 6, 69123 is used Heidelberg] specially for
Windows, by using this program it’s very easy to communicate with other ground
station. configure our TNC7 Multi as well as to choose the proper
modulation technique for communications, compare picture 7.
At SRH Heidelberg we used this program with the need of TNC7 multi to communicate
with Paxon our backup is a very station suitable in Mannhiem. Packet Radio terminal program which
tuns on Windows XP.
Picture 7 : Paxon Software
Figure 3.4.3 Paxon Software
B) EASYSKY
EasySky [10] is an astronomy software that can also be used
[SRH University of Applied Science Heidelberg | Ludwig-Guttmann-Strasse 6, 69123 Heidelberg]
for satellite tracking. It has no connections to GENSO.
However, it can be used to automatically operate HeidelSat
ground station via a PC, compare picture 8.
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� EasySky
!" #$%&'(')*(+%,'-./
Before all manipulation, we have to guaranty that we are connect to the ERAC Telescope. In fact it is
going to command the dish in function of the spacecraft or planet position.
There are 3 softwares to organize this network correctly: We a
� Authentication Servers (A US)
This software is able to validate the
identity of instances of the GSS and
MCC, the following softwares. It allows
maintaining up-to-date lists of the
attributes and statuses of all GENSO
ground stations and spacecraft and
Picture distributing 8 : EasySky these lists to instances of the
GSS and MCC.
C) To GENSO sum up, this software serve the
project infrastructure with network data.
The ground station network GENSO is using a ground station
software standard which allows each ground station to
communicate with non-local spacecraft and share the data
with the spacecraft controllers via internet.
Now we can follow the sun, we need just to click on the sun picture to display the command and
characteristic window:
The GENSO authentication server (AUS) connects ground
stations and mission control centers via a hybrid peer-to-peer
network. It controls the different GENSO ground stations and
is located on one specific maintenance server in Europe.
HeidelSat is
�
controlled
!"#$%&'()*)+#%'(,"-,"'.!((/'
by a Ground Station Server (GSS) and
has also a Mission Control Client (MCC) as an interface
between the GENSO network and satellite communications.
The GSS allows us to automatically track and establish
downlink connections with all compatible participating
spacecraft, compare picture 9.
Picture 9 : Ground station server (GSS)
The MCC is shown in picture 10.
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Picture 10 : Mission control client (MCC)
After finishing all the requirements and installations for the GENZO software Before in our all manipulation, we have to guaranty that we are connect to the ERAC Telescope. In
ground station at SRH Heidelberg, we realized it works perfectly fine instead going of to the command the dish in function of the spacecraft or planet position.
rotor, because it’s a handmade rotor and it doesn’t match with rotor of Genso network
therefore, the rotor software now under constructing and it needs a couple weeks to be
configured and works according to what we are expecting.
[SRH University of Applied Science Heidelberg | Ludwig-Guttmann-Strasse 6, 69123 Heidelberg]
Picture 11 : HeidelSat GENSO hardware schematic
The physical installation, shown in picture 11, allows to
integrate HeidelSat ground station into the GENSO network.
D) DRIVER FOR THE HEIDELSAT ROTATOR
In oder to integrate the HeidelSat ground station into the
GENSO network, it was necessary to write a software driver
for the rotors. All the other GENSO software could be
directly used without modifications.
III. CALIBRATION
With the help of EasySky software, the exact position
of the sun at a given time is exactly known. Like it is shown in
picture 12 and 13, the parabolic antenna is manually pointed
towards the sun, such that the sun shines into the center of a
piece of paper.
On this white paper a black cross indicates the center of the
parabolic dish. When both (shadow and cross) are aligned, the
EasySky software shows the coordinates of the antenna. The
sensors attached to the rotators needs to be configured to the
correct values.
Picture 12 : Sun alignment calibration
� EasySky
Picture 13 : Sun alignment schematic
������
If the calibration is not perfect, it is possible to refine the
position by using the «sun sound». An azimuth scanning
shows where the sound is loudest. Then the same needs to be
done for the elevation. The new coordinates results in a nearly
perfect calibration which suffices for our application.
IV. TRACKING EXAMPLE
Now we can follow the sun, we need just to click on the sun picture to display the command
characteristic window:
IV.1 WITH EASYSKY
Picture 14 : Tracking of satellites with EasySky
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To track space objects, it’s necessary to enter updated Keppler
data, e.g. from the NORAD data base into EasySky.
The PC will then automatically send steering signals to the
rotators and the transceiver can directly communicate with the
the selected space object, compare picture 14.
IV.2 WITH GENSO
Picture 15 : Tracking of satellites with GENSO
Similar to the EasySky software, the GENSO software can be
used to track space objects. However, the GENSO mode
allows also others mission control centers to use HeidelSat
ground station remotely.
V. CONCLUSION
The HeidelSat ground station[11] can be use for the
GENSO network to communicate with satellites that use
amateur radio frequencies in the 2m and the 70cm band. Also
it can be used as an independent ground station in the 2m,
70cm, 23cm and 13cm bands by using EasySky to track
satellites.
VI. REFERENCES
[1] ITU Handbook on satellite communications,international
After finishing all the requirements and installations for the GENZO software in our
groundTelecommunications station at SRH Heidelberg, Union,Wiley,2002
we realized it works perfectly fine instead of the
rotor, because it’s a handmade rotor and it doesn’t match with rotor of Genso network
[2] http://www.amsat.org
therefore, the rotor software now under constructing and it needs a couple weeks to be
configured [3] http://www.iaru.org/satellite
and works according to what we are expecting.
[4] http://www.GENSO.org/
[5] Dennis Roddy, Satellite Commmunications, mcGraw-Hill
professional,2006
[SRH University of Applied Science Heidelberg | Ludwig-Guttmann-Strasse 6, 69123 Heidelberg]
[6] http://www.genso.org
[7] http://www.redlion.net/products/digitalandanalog/
counters/batch/unit counter.html
[8] Bruce Elbert, Introduction to Satellite Communication,
Artech House Publishers; 3 edition, 2008
[9] Mark J. Wilson, The ARRL Operating Manual For Radio
Amateurs,Amer Radio Relay League, 2008
[10] http://www.EasySky.de/eng/
[11] http://www.fh-heidelberg.de/satellit
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