Main transmission

The main transmission takes place when the satellite is actively commanded by the main ground station in Pilsen (Central Europe). Satellite use GomSpace Ax1OO transceiver. Complete decoding can be realized in GNURadio software. All blocks required to decode the satellite transmissions are implemented in the grsatellites project: https://github.com/daniestevez/gr-satellites

Carrier frequency and modulation: 437.325 MHz / GMSK
Symbol rate: 1200 Bd - 9600 Bd (default 4800 Bd)
Framing: GOMSpace AX.100 Mode 5 (ASM+Golay)
Synchronization word: 0xC9D08A7B
Scrambling and FEC: CCSDS, Reed-Solomon (223, 255)
Content: Arbitrary data from the on-board storage

You can use TLE data of ION SCV-004 in early phase of VZLUSAT-2 operation for antenna tracking and Doppler tuning:
1 50993U 22002K 22024.20354232 .00000809 00000+0 50240-4 0 9994
2 50993 97.5064 93.7030 0010438 195.1206 164.9714 15.12431191 1608
We will know own TLE during next few days after VZLUSAT-2 separation from ION SCV-004 adapter.

Beacon signal

If the satellite is out of range of the main ground station, the beacon frames are transmitted every 10 seconds (by default, it can be adjusted occasionally) with a delay of a few minutes after the last contact with the ground station.. Whole beacon structure and source file for decoding are defined in this document: https://www.pilsencube.zcu.cz/vzlusat2/vzlusat2_ham.pdf

Carrier frequency and modulation: 437.325 MHz / GMSK
Symbol rate: 1200 Bd - 9600 Bd (default 4800 Bd)
Content: Protocol header, callsign, OBC Timestamp, OBC Boot count, OBC Reset cause, EPS Battery voltage, EPS Solar current, EPS Current draw, EPS Battery temperature, Radio temperature (power amplifier), Radio total Tx packet count, Radio total Rx packet count

You can use TLE data of ION SCV-004 in early phase of VZLUSAT-2 operation for antenna tracking and Doppler tuning:
1 50993U 22002K 22024.20354232 .00000809 00000+0 50240-4 0 9994
2 50993 97.5064 93.7030 0010438 195.1206 164.9714 15.12431191 1608
We will know own TLE during next few days after VZLUSAT-2 separation from ION SCV-004 adapter.

Data dropper

Data dropper frames are transmitted on uplink command from the ground station or based on command stored inside on-board mission planner. Dropper is a software component facilitating unidirectional broadcast of data for any number of receiving stations. The data frames may contain arbitrary data from the on-board storage (as the main transmission), to be collected by amateur ground stations. Structure of dropped frames is defined in this document: https://www.pilsencube.zcu.cz/vzlusat2/vzlusat2_ham.pdf

SatNOGS support and other information

VZLUSAT-2 is fully supported in SatNOGS ground station network:
https://db.satnogs.org/satellite/DJWH-7860-9983-7310-6047
Also a public dashboard is available, constructed from beacon data:
https://dashboard.satnogs.org/d/L8ywE9oMz/vzlusat-2
The source set of two line elements (TLE) for antenna tracking, Doppler compensation and satellite pass prediction will be published as soon as it is known.