| |
IMPORT > ANS 27.10.24 02:13l 68 Lines 3708 Bytes #121 (0) @ AMSAT
BID : ANS301.4
Read: GUEST
Subj: CatSat Commissioning is Near
Path: IW8PGT<IZ3LSV<DB0ERF<DK0WUE<DK0WUE<VK5RSV<K7EK<KA1VSC<WG3K
Sent: 241027/0109Z 9554@WG3K.#SMD.MD.USA.NOAM LinBPQ6.0.24
CatSat, a 6U cubesat, was blasted into orbit on July 4, 2024. After some
delay, the microwave transponder should be available soon.
The concept was presented at the AMSAT annual symposium on two successive
years. The design has not changed significantly since then. See
https://catsat.arizona.edu for current info.
The project was run by the University of Arizona students with major
support by Rincon Research Corp. (onboard DSP and HF electronics) and
FreeFall Aerospace (patch, HF whip, and high-gain 10 GHz. inflatable
antenna.) The spacecraft bus was supplied by Gomspace.
Something strange happened during launch or satellite deployment, and the
satellite is believed to be damaged by an unknown mechanism. The UHF
command and control antenna appears not to have deployed and the main
spacecraft computer reboots an irregular pattern. The student team has done
an excellent job of keeping the spacecraft under control while
troubleshooting the problems, but this has slowed the commissioning process.
CatSat with inflated spherical microwave antenna *[ArtistâÖs rendering:
University of Arizona]*
*SATELLITE MODES OF PARTICULAR INTEREST TO HAMS*
1. The HF experiment (also known as the WSPR experiment) captures the
entire HF band by sampling it with a 50 MHz analog to digital converter.
Digital processing in an FPGA creates up to four sub-bands which are stored
in CatSat memory. The tuned frequency and bandwidth of these four receivers
will likely be changed from time to time on a schedule to be determined.
Then the captured pre-detection data will be stored in CatSatâÖs AstroSDR
memory until it can be dumped to our 6.1 meter dish in Tucson. There the
sub-band data streams will be extracted and placed on the internet where
interested hams will have access. The intent is to provide an opportunity
for hams to experiment with ionospheric propagation as viewed by a
satellite without having to actually build a ground station. If they work
HF stations using FT-8 or WSPR when the satellite is active they will be
able to use the internet to access what the satellite was hearing. They may
even discover some novel propagation mechanism.
2. At the start of each data capture 32k samples of I-Q data will be
captured at 50 MHz sample rate. These data can be Fourier transformed to
create a spectral power plot of the entire HF band at that location.
3. The 10 GHz downlink modulation is DVB-S2. At the time of planning the
downlink, there was a lot of AMSAT interest in using DVB-S2 as a downlink
modulation for proposed high orbit birds. That drove our decision.
Receiving this link will be a challenge for most stations, unless the
inflatable antenna experiment is successful and we point that antenna at
your location.
4. 5.663 GHz to 10.47 GHz transponder with 200 kHz Bandwidth. During
design review of CatSat it was realized that there was space for an
additional 5 GHz patch antenna on the spacecraft. The AstroSDR could
receive 5.663 GHz and translate it to the IF input of the 10.47 GHz
transceiver. So a 200 KHz linear transponding mode was added. It is one of
the first ham satellites to use these microwave bands.
PHOTO OF CATSAT SPECTRUM Oct 20, 2024 at Tech Park
10 GHz Patch used for transmitting generally pointed towards ground station.
6.1 meter AzArray dish for receiving
Max elevation 29 degrees
LCP on left screen
RCP on right screen
2 MHz/div and 10 dB per division
Comment: Transmitting 2 MSymbols/per second of DVB-S2 Dummy Frames
Strong stable signal smoothly varying with time peaking about 20 dB SNR in
2 MHz band.
[ANS thanks Mike Parker, KT7D for the above information]
Read previous mail | Read next mail
| |
