GNU Radio decoders for Amateur satellites.

gr-satellites is a GNU Radio out-of-tree module encompassing a collection of telemetry decoders that supports many different Amateur satellites. This open-source project started in 2015 with the goal of providing telemetry decoders for all the satellites that transmit on the Amateur radio bands. It supports most popular protocols, such as AX.25, the GOMspace NanoCom U482C and AX100 modems, an important part of the CCSDS stack, the AO-40 protocol used in the FUNcube satellites, and several ad-hoc protocols used in other satellites.

The decoders don't need a graphical interface to run, so they can be used in an embedded or remote computer. They are designed to run in real time and print the telemetry packets to the terminal as they are received. Optionally, the telemetry packets can be uploaded in real time to the SatNOGS database or any other telemetry server that implements the SiDS (Simple Downlink Sharing Convention) protocol.

It is also possible to use the decoder with a recording (audio WAV or IQ file), in case that the telemetry wasn't processed in real time. To do this, one has to know the time and date at which the recording was started and the recording has to be played back at normal speed. This allows the decoder to compute the correct timestamps for the packets when uploading them to the telemetry server. It also simplifies Doppler correction of the recording with Gpredict if the recording was not Doppler corrected.

There are currently three development branches of gr-satellites:

• maint-3.7 Compatible with GNU Radio 3.7 only. No future development will be done on this branch. Perhaps important changes, such as very popular satellites, will be backported from the maint-3.8 branch.

• maint-3.8 Compatible with GNU Radio 3.8 only. Future development is being doing in this branch, adding support to new satellites as they get launched. If contributing to gr-satellites, please send pull requests to maint-3.8 if in doubt.

• next Branch where a large refactor of gr-satellites bringing important changes is being done. Active development is happening, but there are still several months of until the next branch is fully usable.

Starting in 2020, master is set equal to maint-3.8 (before this, it was set equal to maint-3.7).

Regarding the numbered releases, the 1.x.y series is used for stable releases on the maint-3.7 branch (and so, releases supporting GNU Radio 3.7), the 2.x.y series is used for stable releases on the maint-3.8 (and so, releases supporting GNU Radio 3.8), and alpha releases are done on the next branch showcasing some of the latest developments.

First you need to install the dependencies (see below).

After this, gr-satellites must be installed as any other GNU Radio out-of-tree module. The producedure usually boils down to doing the following:

mkdir build
cd build
cmake ..
make
sudo make install
sudo ldconfig

Finally, you need to compile the hierarchical flowgraphs include in gr-satellites (see below).

gr-satellites v2 requires GNU Radio version 3.8.

Required dependencies:

• Phil Karn's KA9Q libfec. A fork that builds in modern linux systems can be found here.
• construct, at least version 2.9.
• requests.
• swig

The following GNUradio out-of-tree modules are only required for the decoder of one particular satellite. You may install only the ones you're interested in.

• beesat-sdr BEESAT and TECHNOSAT decoder and TNC. It is also used for D-STAR One.
• gr-lilacsat This only needs to be installed if you want to submit telemetry to HIT. A complete decoder which does not use gr-lilacsat is already included in gr-satellites.
• PW-Sat2 FramePayloadDecoder This only needs to be installed if you want to parse frames from PW-Sat2. See the instructions here.
• gr-equisat_decoder EQUiSat decoder blocks, telemetry parser, and submitter.

If you want to use any of the realtime image decoders, you also need to install feh.

Some of the decoders use hierarchichal flowgraphs. These are placed in the folder apps/hierarchical. The hierarchical flowgraphs must be compiled and installed before using any of the flowgraphs which include them.

To compile and install the hierarchical flowgraphs, the script compile_hierarchical.sh in the root folder can be used.

The signal is fed to the decoders using a UDP stream. The format used is the same that gqrx uses. Therefore, you can use gqrx to feed the signal to the decoders. You will have to set the proper frequency, mode and bandpass in gqrx for the satellite you want to receive. This is probably the easiest way to start using the decoders from gr-satellites. Gqrx supports Doppler correction with Gpredict.

Note: The exact frequency setting for optimal decoding may need to tuned to properly center the signal within the passband. This is especially true for SSB signals. One way to do this is by using this the Radio Control panel within Gpredict. This allows the user to make small adjustments while monitoring signals in the gqrx passband.

It is also possible to use the frontend streamers from gr-frontends. These allow to stream data by UDP from different SDR hardware without using a GUI SDR program. It remains to perform Doppler correction with Gpredict. There are also frontend streamers to use a conventional receiver connected via soundcard and recordings (audio WAV and IQ).

Each satellite has its own decoder in the apps/ folder. You can open the .grc file with gnuradio-companion and edit the parameters (they are on the upper part of the flowgraph). You can also generate and run the corresponding .py script and specify the parameters on the command line. Use the -h flag to get help on how to specify the parameters. The decoder will printing each telemetry packet in the terminal as soon as it receives it.

• sat_1kuns_pf 1KUNS-PF, which transmits 1k2 or 9k6 GMSK telemetry in the 70cm band. It uses the GomSpace NanoCom AX100 transceiver in ASM+Golay mode. This uses a CCSDS scrambler and a (255,223) Reed-Solomon code. You must use FM mode to receive this satellite (437.300 MHz). 1KUNS-PF transmits JPEG images from an onboard camera. This decoder includes an image decoder which shows the images in real time using feh.
• sat_3cat_1 3CAT-1, which transmits 9k6 GFSK telemetry in the 70cm band. It uses a Texas Intruments CC1101 transceiver with a PN9 scrambler, and a (255,223) Reed-Solomon code from the rscode library. You must use FM mode to receive this satellite (437.250MHz).
• sat_3cat2 3CAT-2 (inactive), which transmits 9k6 AX.25 BPSK telemetry in the 2m band. You must use wide SSB mode to receive this satellite.
• aausat_4 AAUSAT-4, which transmits 2k4 or 9k6 GFSK telemetry in the 70cm band. It uses the CSP protocol and FEC with an r=1/2, k=7 convolutional code and a (255,223) Reed-Solomon code. You must use FM mode to receive this satellite (437.425MHz).
• aisat AISAT, which transmits 4k8 AF GMSK telemetry in the 70cm band. It uses a NanoCom U482C transceiver with the CSP protocol and FEC with a (255,223) Reed-Solomon code. It also uses a CCSDS scrambler. There is no telemetry parser yet, as the beacon format is unknown. This satellite has an AIS receiver on board. You must use FM mode to receive this satellite.
• aistechsat2 AISTECHSAT-2, which transmits 4k8 or 9k6 GMSK telemetry in the 70cm band. It uses the GomSpace NanoCom AX100 transceiver in ASM+Golay mode. This uses a CCSDS scrambler and a (255,223) Reed-Solomon code. You must use FM mode to receive this satellite (436.730MHz).
• aistechsat3 AISTECHSAT-3, which transmits 4k8 or 9k6 GMSK telemetry in the 70cm band. It uses the GomSpace NanoCom AX100 transceiver in ASM+Golay mode. This uses a CCSDS scrambler and a (255,223) Reed-Solomon code. The telemetry format is documented but a telemetry decoder has not been implemented yet. You must use FM mode to receive this satellite (436.730MHz).
• amgu_1 AmGU-1, which transmits 4k8 FSK telemetry in the 70cm band. It uses the Mobitex protocol, which includes FEC with a (12,8,3) linear code and CRC-16CCITT for error detection. The decoder requires the beesat-sdr OOT module. You must use FM mode to receive this satellite (436.250MHz).
• ao40_uncoded AO-40 (inactive), which transmitted 400bps BPSK telemetry in several bands. This decoder is for the uncoded telemetry, which did not use any forward error correction. The specifications of the telemetry can be found in this document. AO-40 is no longer functional, but it is of high historic interest. You must use SSB mode to receive this satellite.
• ao73 AO-73 (FUNcube), which transmits 1k2 BPSK telemetry in the 2m band. It uses the AO-40 FEC protocol, which includes block interleaving, an r=1/2, k=7 convolutional code, CCSDS scrambling and two interleaved (160,128) Reed-Solomon codes. You must use SSB mode to receive this satellite (145.935MHz).
• astrocast, astrocast_old, astrocast_9k6 Astrocast 0.1, which transmits 1k2 FSK telemetry in the 70cm band. It uses the FX.25 protocol with a (255,223) CCSDS Reed-Solomon code. The astrocast_old decoder is for the protocol variant used until 2019-02-13, which wast not completely compatible with AX.25. The astrocast_9k6 decoder is for the 9k6 FSK protocol used for data download. This uses five interleaved (255,223) CCSDS Reed-Solomon codewords following the CCSDS standard. You must use FM mode to receive this satellite (437.150MHz).
• at03 QB50 AT03 (PEGASUS), which transmits 9k6 GFSK telemetry in the 70cm band. It uses the TT-64 protocol, which includes a CRC16-ARC and FEC with a (64,48) Reed-Solomon code. Reed-Solomon decoding is done with the rscode library. You must use FM mode to receive this satellite (436.670MHz).
• athenoxat-1 ATHENOXAT-1, which transmits 4k8 AF GMSK telemetry in the 70cm band. It uses a NanoCom U482C transceiver, with the CSP protocol and FEC with a (255,223) Reed-Solomon code. It also uses a CCSDS scrambler. There is no telemetry parser yet, as the beacon format is unknown. This satellite is on a low inclination orbit, so it can only be received near the equator. You must use FM mode to receive this satellite (437.485MHz).
• atl_1 ATL-1, which transmits 1.25k, 2.5k, 5k or 12.5k FSK telemetry in the 70cm band. It uses the AO-40 FEC protocol, which includes block interleaving, an r=1/2, k=7 convolutional code, CCSDS scrambling and two interleaved (160,128) Reed-Solomon codes. You must use FM mode to receive this satellite (437.175MHz).
• au02 QB50 AU02 (UNSW-EC0), which transmits 4k8 AF GMSK telemetry in the 70cm band. It uses a NanoCom U482C transceiver, with the CSP protocol and FEC with an r=1/2, k=7 convolutional code and a (255,223) Reed-Solomon code. It also uses a CCSDS scrambler. You must use FM mode to receive this satellite (436.525MHz).
• au03 QB50 AU03 (i-INSPIRE II), which transmits 4k8 AF GMSK telemetry in the 70cm band. It uses a NanoCom U482C transceiver, with the CSP protocol and FEC with an r=1/2, k=7 convolutional code and a (255,223) Reed-Solomon code. It also uses a CCSDS scrambler. You must use FM mode to receive this satellite (436.330MHz).
• beesat BEESAT-1,-2,-4 and -9 and TECHNOSAT, which transmit 4k8 FSK telemetry in the 70cm band. They use the Mobitex-NX protocol, which includes FEC with a (12,8,3) linear code and CRC-16CCITT for error detection. The decoder requires the beesat-sdr OOT module. You must use FM mode to receive these satellites (435.950MHz).
• by701 BY70-1 (inactive), which transmits 9k6 BPSK telemetry in the 70cm band. It uses FEC with an r=1/2, k=7 convolutional code and a (255,223) Reed-Solomon code (the same as the LilacSat-2 9k6 BPSK telemetry). You must use wide SSB mode to receive this satellite. It has an optical camera on board and it transmits JPEG images together with the telemetry. by701 includes a complete telemetry decoder and image receive software. This satellite launched on 28 December 2016 into a 520x220km orbit. The perigee is too low because of a problem in the launch. BY70-1 reentered on 18 February 2017. You must use wide SSB mode to receive this satellite.
• ca03 QB50 CA03 (Ex-Alta 1), which transmits 4k8 GFSK telemetry in the 70cm band. Occasionaly it has been seen to transmit in 9k6. It uses the CSP protocol and FEC with a (255,223) Reed-Solomon code. It also uses a G3RUH scrambler. The transceiver is the GomSpace NanoCom AX100, the same transceiver used in GOMX-3. You must use FM mode to receive this satellite (436.705MHz).
• cz02 QB50 CZ02 (VZLUSAT-1), which transmits 4k8 AF GMSK telemetry in the 70cm band. It uses a NanoCom U482C transceiver, with the CSP protocol and a (255,223) Reed-Solomon code. It also uses a CCSDS scrambler. You must use FM mode to receive this satellite (437.240MHz).
• delphini1 Delphini-1, which transmits 4k8 GMSK telemetry in the 70cm band. It uses the GomSpace NanoCom AX100 transceiver in ASM+Golay mode. This uses a CCSDS scrambler and a (255,223) Reed-Solomon code. You must use FM mode to receive this satellite (437.500MHz).
• dsat D-SAT (inactive), which transmits 4k8 AF GMSK telemetry in the 70cm band. It uses a NanoCom U482C transceiver with the CSP protocol and FEC with a (255,223) Reed-Solomon code. It also uses a CCSDS scrambler. This receiver supports sending frames to the D-SAT groundstation software, which decodes telemetry. See this post for detailed instructions. D-SAT transmits JPEG images from an onboard camera. This decoder includes an image decoder which shows the images in real time using feh.
• dstar_one D-STAR One, which transmits 4k8 FSK telemetry in the 70cm band. It uses the Mobitex protocol, which includes FEC with a (12,8,3) linear code and CRC-16CCITT for error detection. The decoder requires the beesat-sdr OOT module. You must use FM mode to receive this satellite (435.700MHz).
• duchifat_3 DUCHIFAT-3, which transmits 9k6 AX.25 BPSK telemetry in the 70cm band. It uses a G3RUH scrambler. You must use wide SSB mode to receive this satellite (436.400MHz).
• entrysat EntrySat, which transmits 9k6 AX.25 BPSK telemetry in the 70cm band. It uses a G3RUH scrambler. You must use wide SSB mode to receive this satellite (436.950MHz).
• equisat EQUiSat, which transmits 9k6 baud 4FSK telemetry in the 70cm band. It uses a double-interleaving encoding and a (255,223) Reed-Solomon code. The decoder requires the gr-equisat_decoder OOT module. You must use FM mode to receive this satellite (435.525MHz). For more info see brownspace.org/receiving-equisat, and see below for how to submit to the telemetry database.
• eseo ESEO, which transmits 9k6 or 4k8 GFSK telemetry in the 70cm band. It uses a custom protocol vaguely similar to AX.25 with some form of G3RUH scrambling and a (255,239) Reed-Solomon code. You must use FM mode to receive this satellite (437.000MHz).
• facsat_1, FACSAT-1, which transmits 9k6 GMSK telemetry in the 70cm band. It uses the GomSpace NanoCom AX100 transceiver in ASM+Golay mode. This uses a CCSDS scrambler and a (255,223) Reed-Solomon code. The telemetry format is unknown. You must use FM mode to receive this satellite (437.350MHz).
• floripasat_1, FloripaSat-1, which transmits 1k2 FSK telemetry in the 2m band (beacon) and 2k4 FSK telemetry in the 70cm band (downlink). It uses the NGHam protocol and AX.25, but the Reed-Solomon of NGHam and the complete AX.25 seem to be not correctly implemented. You must use FM mode to receive this satellite (145.900MHz for beacon and 436.1MHz for downlink).
• fmn1 FMN-1, which transmits 9k6 AX.25 BPSK telemetry in the 70cm band. It uses a G3RUH scrambler. You must use wide SSB mode to receive this satellite (435.350MHz).
• galassia GALASSIA, which transmits 4k8 AF GMSK telemetry in the 70cm band. It uses a NanoCom U482C transceiver with the the CSP protocol and FEC with a (255,223) Reed-Solomon code. It also uses a CCSDS scrambler. There is no telemetry parser yet, as the beacon format is unknown. This satellite is on a low inclination orbit, so it can only be received near the equator. You must use FM mode to receive this satellite.
• gomx_1 GOMX-1, which transmits 4k8 AF GMSK telemetry in the 70cm band. It uses a NanoCom U482C transceiver with the CSP protocol and FEC with a (255,223) Reed-Solomon code. It also uses a CCSDS scrambler. The beacons include information from ADS-B beacons transmitted by terrestrial aircraft. You must use FM mode to receive this satellite (437.255MHz).
• gomx_3 GOMX-3 (inactive), which transmits 19k2 GFSK telemetry in the 70cm band. It uses the CSP protocol and FEC with a (255,223) Reed-Solomon code. It also uses a G3RUH scrambler. The beacons include information from ADS-B beacons transmitted by terrestrial aircraft. GOMX-3 reentered on 18 October 2016. You must use FM mode to receive this satellite.
• gr01 QB50 GR01 (DUTHSat) (inactive), which transmits 1k2 or 9k6 AX.25 BPSK telemetry in the 70cm band. It uses a G3RUH scrambler. For 1k2 telemetry you must use SSB mode, while for 9k6 telemetry you must use wide SSB mode.
• il01 QB50 IL01 (DUCHIFAT-2), which transmits 9k6 AX.25 BPSK telemetry in the 70cm band. It uses a G3RUH scrambler. You must use wide SSB mode to receive this satellite (437.740MHz).
• indus Mystery satellite transmitting on 435.080MHz using 1k2 FSK AX.25 and the callsign INDUSR-10 (see here).
• innosat_2, INNOSAT-2, which transmits 4k8 GMSK telemetry in the 70cm band. It uses the GomSpace NanoCom AX100 transceiver in ASM+Golay mode. This uses a CCSDS scrambler and a (255,223) Reed-Solomon code. You must use FM mode to receive this satellite (437.450MHz).
• itasat1 ITASAT 1, which transmits 1k2 AX.25 BPSK telemetry in the 2m band. You must use SSB mode to receive this satellite (145.860MHz).
• jy1sat JY1-Sat (FUNcube-6), which transmits 1k2 BPSK telemetry in the 2m band. It uses the AO-40 FEC protocol, which includes block interleaving, an r=1/2, k=7 convolutional code, CCSDS scrambling and two interleaved (160,128) Reed-Solomon codes. Decoding SSDV images is supported. See this post. You must use SSB mode to receive this satellite (145.840MHz).
• k2sat_image K2SAT, which transmits images using QPSK in the 13cm band. See this post.
• kr01 QB50 KR01 (LINK) (inactive), which transmits 9k6 AX.25 BPSK telemetry in the 70cm band. It uses a G3RUH scrambler. Currently it transmits 1k2 telemetry (safe mode perhaps), so you must use SSB mode to receive this satellite.
• ks_1q KS-1Q (inactive), which transmits 20k FSK telemetry in the 70cm band. It uses KISS framed CSP packets and FEC with an r=1/2, k=7 convolutional code and a (255,223) Reed-Solomon code (the protocol is very similar to LilacSat-2). It also uses a CCSDS scrambler. You must use FM mode to receive this satellite.
• lilacsat1 LilacSat-1 (inactive), which transmits 9k6 BPSK telemetry in the 70cm band. It uses FEC with an r=1/2, k=7 convolutional code an interleaved telemetry and Codec2 digital voice. It has an optical camera on board and it transmits JPEG images together with the telemetry. LilacSat-1 reentered in March 2019. You must use wide SSB mode to receive this satellite.
• lilacsat2 LilacSat-2, which transmits 9k6 BPSK, 4k8 GFSK and FM subaudio telemetry in the 70cm band. It uses FEC with an r=1/2, k=7 convolutional code and a (255,223) Reed-Solomon code. The decoders for this satellite are organized a bit different from the decoders for other satellites, because LilacSat-2 transmits in several different frequencies using several different modes. You can use lilacsat2 as a usual single-frequency single-mode decoder. You can use gqrx or one of the frontends from gr-frontends to feed an UDP audio stream to lilacsat2. However, you can decode only one frequency and mode using this method. You should tune to 437.200MHz in wide SSB mode to receive 9k6 BPSK telemetry, to 437.200MHz in FM mode to receive FM subaudio telemetry and to 437.225MHz in FM mode to receive 4k8 GFSK telemetry. lilacsat2 will recognise the telemetry format automatically. To receive all the frequencies and modes at the same time, you need to use an SDR receiver. The receivers lilacsat_fcdpp and lilacsat_rtlsdr can be used with a FUNcube Dongle Pro+ and an RTL-SDR respectively. These are complete receivers and decoders. They submit telemetry to the SatNOGS database and can use Doppler correction with Gpredict, in the same way as the frontends from gr-frontends. For lilacsat_fcdpp and lilacsat_rtlsdr, when using Doppler correction with Gpredict, you have to set 437.200MHz as the downlink frequency in Gpredict.
• lucky_7 Lucky-7, which transmits 4k8 GFSK telemetry in the 70cm band. It uses a SiLabs Si4463 transceiver with a PN9 scrambler and a CRC-16. You must use FM mode to receive this satellite (437.525MHz).
• lume1 LUME-1, which transmits 4k8 GMSK telemetry in the 70cm band. It uses the GomSpace NanoCom AX100 transceiver in ASM+Golay mode. This uses a CCSDS scrambler and a (255,223) Reed-Solomon code. You must use FM mode to receive this satellite (437.060MHz).
• luojia_1 Luojia-1, which transmits 4k8 GMSK telemetry in the 70cm band. It uses the GomSpace NanoCom AX100 transceiver in ASM+Golay mode. This uses a CCSDS scrambler and a (255,223) Reed-Solomon code. You must use FM mode to receive this satellite (437.250 MHz).
• mysat1 MYSAT 1, which transmits 1k2 or 9k6 AX.25 BPSK telemetry in the 70cm band. It uses a G3RUH scrambler. For 1k2 telemetry you must use SSB mode, while for 9k6 telemetry you must use wide SSB mode (435.77MHz).
• nayif1 Nayif-1 (FUNcube-5), which transmits 1k2 BPSK telemetry in the 2m band. It uses the AO-40 FEC protocol, which includes block interleaving, an r=1/2, k=7 convolutional code, CCSDS scrambling and two interleaved (160,128) Reed-Solomon codes. You must use SSB mode to receive this satellite (145.940MHz).
• nusat ÑuSat-1 and -2, which transmit 40k FSK telemetry in the 70cm band (ÑuSat-1 on 436.445, ÑuSat-2 on 437.455). They use FEC with a (64, 60) Reed-Solomon code and a CRC-8. Since a sample rate of 48kHz is too low to work with 40k FSK, the flowgraph is prepared to use an IQ recording at 192kHz. Depending on the characteristics of your IQ recording you may need to edit the flowgraph. The Reed-Solomon decoder is taken from the rscode library. A sample IQ recording is included in satellite-recordings.
• ops_sat OPS-SAT, which transmits 9k6 AX.25 telemetry in the 70cm band. It uses a G3RUH scrambler and the frames are encoded using a CCSDS Reed-Solomon code and a CCSDS scrambler. You must use FM mode to receive this satellite (437.200 MHz).
• picsat PicSat, which transmits 1k2 or 9k6 AX.25 BPSK telemetry in the 70cm band. It uses a G3RUH scrambler. For 1k2 telemetry you must use SSB mode, while for 9k6 telemetry you must use wide SSB mode (435.525MHz).
• pwsat2 PW-Sat2, which transmits 1k2, 2k4, 4k8 or 9k6 AX.25 BPSK telemetry in the 70cm band. It uses a G3RUH scrambler. Currently the decoder only supports 1k2 or 9k6, since it is not clear if the other baudrates will be ever used. Telemetry parsing is supported using the external PW-Sat2 software. See here for the instructions. Uploading to the PW-Sat2 Telemetry Server is also supported. See here for the instructions. For 1k2 telemetry you must use SSB mode, while for 9k6 telemetry you must use wide SSB mode (435.275MHz).
• qo100 QO-100 (Es'hail 2 AMSAT Phase 4-A), which transmits a 400baud BPSK beacon in the 3cm band. The beacon is relayed from the control centre in Qatar via a 13cm/3cm linear transponder on the satellite. The format of the telemetry is the same as that of the AO-40 beacon. Uncoded and FEC frames are sent alternatively. You must use SSB mode to receive this satellite (10489.800MHz).
• reaktor_hello_world Reaktor Hello World, which transmits 9k6 GFSK telemetry in the 70cm band. It uses a Texas Intruments CC1125 transceiver with a PN9 scrambler and a CRC-16. You must use FM mode to receive this satellite (437.775MHz).
• shaonian_xing Shaonian Xing (MXSat-1), which transmits 9k6 AX.25 BPSK telemetry in the 70cm band. It uses a G3RUH scrambler. You must use wide SSB mode to receive this satellite (436.375MHz).
• smog_p SMOG-P, which transmits 1.25k, 2.5k, 5k or 12.5k FSK telemetry in the 70cm band. It uses the AO-40 FEC protocol, which includes block interleaving, an r=1/2, k=7 convolutional code, CCSDS scrambling and two interleaved (160,128) Reed-Solomon codes. You must use FM mode to receive this satellite (437.150MHz).
• snet S-NET A,B,C,D, which transmit 1k2 AFSK telemetry in the 70cm band. They use a custom coding with BCH FEC and interleaving. You must use FM mode to receive these satellites (435.950MHz).
• sokrat Sokrat, which transmits 4k8 FSK telemetry in the 70cm band. It uses the Mobitex protocol, which includes FEC with a (12,8,3) linear code and CRC-16CCITT for error detection. The decoder requires the beesat-sdr OOT module. You must use FM mode to receive this satellite (436.000MHz).
• spooqy_1 SpooQy-1, which transmits 9k6 GMSK telemetry in the 70cm band. It uses the GomSpace NanoCom AX100 transceiver in ASM+Golay mode. This uses a CCSDS scrambler and a (255,223) Reed-Solomon code. The telemetry format is unknown. You must use FM mode to receive these satellites (436.200MHz).
• suomi_100 Suomi 100, which transmits 9k6 GMSK telemetry in the 70cm band. It uses the GomSpace NanoCom AX100 transceiver in ASM+Golay mode. This uses a CCSDS scrambler and a (255,223) Reed-Solomon code. You must use FM mode to receive this satellite (437.775MHz).
• swiatowid Światowid, which transmits 9k6 FSK image data in the 70cm band. It uses a custom protocol with a (58,48) Reed-Solomon code and a CRC-16CCITT. You must use FM mode to receive this satellite (435.500MHz). Światowid also transmits standard 1k2 AFSK AX.25 APRS in the same frequency. The APRS data can be received with the generic_1k2_afsk_ax25 decoder.
• tanusha3_pm TANUSHA-3, which transmits FM audio, 1k2 AX.25 AFSK telemetry and 1k2 audio frequency phase modulation AX.25 telemetry in the 70cm band. This decoder is for the phase modulation packets. For the AFSK packets you can use any regular packet decoder such as direwolf. You must use FM mode to receive this satellite (437.050MHz).
• taurus1 Taurus-1, which transmits 9k6 BPSK telemetry in the 70cm band. It uses FEC with an r=1/2, k=7 convolutional code an interleaved telemetry and Codec2 digital voice. You must use wide SSB mode to receive this satellite (435.840MHz).
• tw_1a, tw_1b, tw_1c TW-1A, TW-1B, TW-1C, which transmit 4k8 GFSK telemetry in the 70cm band. They use the CSP protocol and FEC with a (255,223) Reed-Solomon code. They also use a G3RUH scrambler. The transceiver is the GomSpace NanoCom AX100, the same transceiver used in GOMX-3. There is no beacon parser yet, as the beacon format is unknown. The only difference between the 3 receivers is that the NORAD ID is set for the correct satellite when doing telemetry submission. You must use FM mode to receive these satellites. TW-1A, TW-1C (435.645 MHz), TW-1B (437.645 MHz).
• ty_2, ty_4, ty_6 TY-2, TY 4-01, and TY-6, which transmit 9k6 GMSK telemetry in the 70cm band. They use the GomSpace NanoCom AX100 transceiver in ASM+Golay mode. This uses a CCSDS scrambler and a (255,223) Reed-Solomon code. The telemetry format is unknown. The only difference between the 2 receivers is that the NORAD ID is set for the correct satellite when doing telemetry submission. You must use FM mode to receive these satellites. TY-2 (435.350MHz), TY 4-01 (435.925MHz), TY-6 (436.100MHz).
• ua01 QB50 UA01 (PolyITAN-2-SAU), which transmits 9k6 AX.25 BPSK telemetry in the 70cm band. It uses a G3RUH scrambler and two stages of NRZI coding. You must use wide SSB mode to receive this satellite (436.600MHz).
• ukube1 UKube-1 (FUNcube-2), which transmits 1k2 BPSK telemetry in the 2m band. It uses the AO-40 FEC protocol, which includes block interleaving, an r=1/2, k=7 convolutional code, CCSDS scrambling and two interleaved (160,128) Reed-Solomon codes. You must use SSB mode to receive this satellite (145.915MHz).
• zhou_enlai Zhou Enlai, which transmits 9k6 AX.25 BPSK telemetry in the 70cm band. It uses a G3RUH scrambler. You must use wide SSB mode to receive this satellite (437.644MHz).

I do not add specific decoders to gr-satellites for satellites using standard AFSK or FSK AX.25 packet radio, since there are many satellites using these modes and there are already very good decoders for packet radio such as direwolf. However, in case someone finds it useful, I have added generic_4k8_fsk_ax25, generic_9k6_fsk_ax25 and generic_19k2_fsk_ax25 generic decoders for 4k8, 9k6 and 19k2 FSK AX.25 packet radio. Additionally, there is generic_1k2_afsk_ax25 for 1k2 AFSK AX.25 packet radio. Note that the performance of the AFSK decoder may not be optimal due to improvable aspects in the signal processing (designing a good AGC is a challenge, for instance).

Descriptions for these blocks have been added in CCSDS_README.md file.

To sumbit telemetry to the SatNOGS database (or another SiDS telemetry server), you have to specify your callsign and coordinates. The callsign is specified using the --callsign parameter and the latitude and longitude are specified using the --latitude and --longitude parameters if you are using the .py script. If you are using the .grc file with gnuradio-companion, you can set these parameters by editing the boxes on the upper part of the flowgraph.

The format for the latitude and longitude is of the form 00.00000 or -00.00000. The - means South (for latitude) or West (for longitude).

If you want to submit telemetry from a recording, you have to specify the UTC date and time when the recording was started. This allows the decoder to compute the proper timestamp for the packets. The format is YYYY-MM-DD HH:MM:SS and it is specified using --recstart if using the .py script or with the parameter box on the upper part of the flowgrah if using the .grc file with gnuradio-companion.

It is also very important that the decoder and the recording streamer are started simultaneously. This can be achieved by something like

gr-frontends/wav_48kHz.py -f recording.wav & \
gr-satellites/sat_3cat2.py --recstart="2016-01-01 00:00" --callsign=N0CALL --latitude=0.000 --longitude=0.000

There are many satellites that use standard packet radio AX.25 and can be received with any software TNC such as Direwolf. gr-satellites includes kiss_submitter to perform telemetry submission when using a software TNC.

kiss_submitter connects to the software TNC as a KISS TCP client. The frames received by the software TNC will be submitted by kiss_submitter. To use kiss_submitter, you must specify your callsign and coordinates as when submitting telemetry using any of the decoders. You also need to specify the NORAD ID of the satellite you are receiving. This can be done by setting using --norad if using the .py script or with the parameter if using the .grc file. It is very important that you set the NORAD ID correctly. You can search the NORAD ID in celestrak.

You must start the software TNC first and the run the .py script or the .grc file for kiss_submitter.

The flowgraphs for the different FUNcube satellites/payloads also support submitting telemetry to the FUNcube server. To use this, you need to obtain the "Site Id" (your username) and "Auth code" from your account on the FUNcube server. These parameters can then be indicated by using the --site-id and --auth-code if using the .py script or by editing the boxes in the lower right part of the flowgraph if using the .grc file.

It is also possible to use the flowgraphs in gr-satellites to submit telemetry to the Harbin Institute of Technology servers using proxy_publish.py in gr-lilacsat/examples/proxy_publish. To enable this, you must open the flowgraphs in gnuradio-companion and enable the "Socket PDU" block (usually on the lower right corner of the flowgraph). This block is disabled by default because when it is enabled the flowgraph won't run unless proxy_publish.py is running. Also see this information about how to set the proper ports in proxy_publish.py.

To submit telemetry to the BME server you first need to register an account there. Then modify the "BME Telemetry Forwarder" in the GRC flowgraph to include your username and password.

The EQUiSat flowgraph also supports submitting telemetry to the Brown Space Engineering data server. To use this, you need to obtain an API key from the server. This can be done simply with the following command:

    curl -s -X POST http://api.brownspace.org/equisat/generate-key

The API key returned from this can then be specified using the --api-key parameter if using the .py script or by editing the box in the upper middle part of the flowgraph if using the .grc file.

You can also specify similar submit metadata as the SatNOGS submitter (above), such as your callsign and location. See python equisat.py --help for all the options.

Some modes (9k6 BPSK, for instance) need to be received using SSB mode, but the bandwidth of the signal is larger than the usual 3kHz bandwidth of a conventional SSB receiver. Therefore, an SDR receiver or a heavily modified conventional SSB receiver is needed (a 9k6 BPKS signal is about 15kHz wide).

The decoders for satellites using these kind of wide SSB signals expect the signal to be centred at an audio frequency of 12kHz. This means that you have to dial in USB mode to a frequency 12kHz lower than the nominal frequency of the satellite (+/- Doppler). If your SDR program allows this (gqrx does), the best idea is to set an SSB audio filter from 0Hz to 24kHz and then tune the signal in the middle of the passband. Alternatively, you can use the --bfo parameter if using the .py file or edit the corresponding parameter in the .grc file to use a frequency different from 12kHz.

If you are using the wide SSB receivers from gr-frontends you don't need to do anything special, as these receivers already dial in USB mode to a frequency 12kHz than the nominal and use a 24kHz wide audio filter.

We are all used to the two SSB modes: USB (which is sideband-preserving) and LSB (which is sideband-inverting). When receiving FM (or FSK), there is the same concept. An FM receiver can be sideband-preserving or sideband-inverting. This makes no difference when receiving analog FM (both sound the same) or AX.25 (which uses a differential protocol).

However, some satellites which use FSK (AAUSAT-4 and GOMX-3, for instance) need a sideband-preserving FM receiver. If your receiver is sideband-inverting, you can use set --invert=-1 while running the .py file or edit the corresponding parameter in the .grc file to invert the signal again in the decoder and recover the original signal with the correct sidebands.

To run the decoder and save the output to a file, it is possible to do something like

python2 -u aausat_4.py | tee /tmp/aausat4.log

This will both print the beacons in real time and also save all the output to the text file /tmp/aausat4.log.