This project is implemented with financial support from the state budget through the Ministry of Industry and Trade in TRIO program.
BDSAT project aims to support the radio amateur community with several HAM services and activities. Secondary goal is a verification of a prototype of pressure measuring equipment and to verify the functionality of this technology in open space conditions. The function of the measurement itself, its feasibility and suitability for use in satellites in space conditions will be verified. The second part of the technological experiment is to verify use of supercapacitors as a modern approach to energy storage in satellites.
BDSAT is a satellite built for radio amateurs. Creators and supporters of BDSat project have great passion for space radio amateur activities and are already involved in two radio amateur mission from the region, skCUBE and GRBAlpha. Both of them very successful and popular in the community.
BDSAT is the nanosatellite, so-called the Cubesat, sized 10x10x10 cm. Nanosatellite space technology is a major technological trend.
Despite their small size and weight, Cubesats are taking over some roles of the larger satellites as it is a low-cost option for developing and testing new technologies in space.
The BDSAT project is divided into two parts. First at all, it will test BD SENSORS pressure transmitters in open space conditions. These transmitters have to meet very demanding requirements both in terms of survival in harsh space conditions and in terms of maintaining accuracy and other technical parameters. The reliability of the technology is essential to the future space applications.
A base station for communication with the satellite will be located at the co-investigator CEITEC VUT, which will provide the command and data collection from the satellite.
The experiment also includes verifying the function of the supercapacitor bank. It is a powerful source for storing electricity for satellite systems. In the future, a supercapacitor bank can replace conventional battery power systems. The system will be charged with energy from solar panels during the flight phase facing the Sun. During the second phase of the flight without the power from the solar panels, the energy from this source will be discharged to an artificial load.
After launching the nanosatellite into an orbit, regular monitoring and data collection will take place to check the proper functioning of the pressure sensor and the supercapacitor´s bank, their temperature dependence, and degradation influenced by the time and radiation.
The supercapacitor’s bank will also be assessed for the ability to maintain energy in space. In addition to data from verification experiments, operational data of nanosatellite will be monitored.
Printed circuit boards for the Engineering model (EM) are currently being installed. On this model of the BDSAT cubesat, all the functionality of the proposed satellite concept will be tested. In this phase of development, we are able to detect possible errors before building your own satellite flying into the universe.
EM is built according to the same procedures as the resulting flight model (so-called Flight model – FM), but it is not intended to be launched into space. This model serves only as a training unit, which is used for testing, for example, the assembly of individual components into the final unit, the functionality of HW and many other things that are better to be tested just before launching an expensive flight model. It will also be very important to test the software of the on-board computer controlling and coordinating all satellite activity.
UHF Downlink frequency: 436.025 MHz +/- Doppler shift
VHF Downlink frequency: 145.850 MHz +/- Doppler shift
Modulation: GFSK, CW
Encoding: G3RUH 9k6 baud
Morse: 20 WPM
Protocols: AX.25, Morse
Transmitting power: 1W (30dBm)
Onboard antenna: Dipole
Antenna polarization: Linear
MYCALL [Your call sign]
UNPROTO CQ (or callsign)
Orbit: 500km SSOBDSat2-
1 11111U 23998A 23003.66285800 .00000000 00000-0 00000-0 0 00002
2 11111 97.6096 65.4602 0008334 174.7576 182.8383 15.11265846540003
1. AX.25 TRX beacon packet
2. AX.25 OBC beacon packet
3. AX.25 PSU beacon packet
4. AX.25 BDS Payload beacon packet
5. AX.25 message
6. CW data beacon
7. CW message beacon
8. Ground Station communication
Note: Examples from EM satellite model.
The transmission period is following:
OBC/PSU/BDS AX.25 beacon every 90s (UHF)
TRX UHF AX.25 beacon every 60s
TRX UHF AX.25 message every 300s
TRX VHF AX.25 beacon every 180s
TRX UHF Morse beacon every 180s
There are offsets applied between transmissions.
Example of decoded AX.25 TRX beacon packets
Data in AX.25 TRX beacon packet values are comma-separated.
1:Fm OK0BDT To CQ <UI R Pid=F0 Len=54> [14:00:38R] [AA] [+++++++]
1. Beacon identification [U – UHF, V – VHF]
2. Uptime since reset [s]
3. Uptime total [s]
4. Radio boot count
5. RF segment reset count
6. Radio MCU act. temperature [0.01°C]
7. RF chip act. temperature [0.01°C]
8. RF power amplifier act. temperature [0.01°C]
9. Digipeater forwarded message count
10. Last digipeater user sender’s callsign [ASCII, 6 spaces means nobody yet]
11. RX data packets (AX25 with CRC matched, includes CSP and digipeater packets)
12. TX data packets (includes CSP and digipeater packets)
13. Actual RSSI, ((value / 2) – 134) [dBm]
14. Value of RSSI when carrier detected – after preamble ((value / 2) – 134) [dBm]
Example of decoded AX.25 OBC beacon packet
OBC packet is a packet created by Eddie Onboard Computer including selected interesting values from
onboard BDSat-2 subsystems. Values are comma separated.
1:Fm OK0BDT To CQ <UI R Pid=F0 Len=63> [15:12:03R] [AA] [+++++++]
1. OBC – Packet identification
2. rst – Boot count
3. uptime – Uptime [s]
4. uptimeTot – Total uptime [s]
5. bat – Analog measured battery level [mV]
6. tempMCU – MCU temperature [0.01°C]
7. tempBRD – Board temperature [0.01°C]
8. tempS1 – Solar temperature [0.01°C]
9. tempS2 – Solar temperature [0.01°C]
10. tempS3 – Solar temperature [0.01°C]
11. tempS4 – Solar temperature [0.01°C]
12. tempS5 – Solar temperature [0.01°C]
13. freemem – Remaining storage space
Example of decoded AX.25 PSU beacon packet
PSU packet is created by the OBC. Values are comma separated.
1:Fm OK0BDT To CQ <UI R Pid=F0 Len=50> [15:12:18R] [AA] [+++++++]
1. PSU – Packet identification
2. rst – PSU reset number
3. uptime – Current uptime since last reset [s]
4. totalUptime – Total uptime cumulative [s]
5. bat – Battery voltage [mV]
6. tempSys – System temperature [0.01°C]
7. tempBat – Battery temperature [0.01°C]
8. curIn – Battery current in [mA]
9. curOut– Battery current out [mA]
10. chStat – Bit-Masked channel status *
11. sysState – System state **
12. gndWdt – Remaining ground watchdog timer [h]
* Bit 0 – Channel 0, 0/1 – Off/On (channels from 0 to 6)
** 1 – Okay, 2 – Power saving, 3 – Power critical
Example of decoded AX.25 BDS payload beacon packet
BDS payload packet is created by the OBC. Values are comma separated.
1:Fm OK0BDT To CQ <UI R Pid=F0 Len=94> [15:12:19R] [AA] [+++++++]
1. BDS – Packet identification
2. state – Payload state
3. progId – Payload program ID
4. hwState – Payload HW config mask (00 – off, 1x – E1 on, x1 – E2 on)
5. cron – Payload program running automatically
6. tmpC0 – temperature C0 [0.01°C]
7. tmpC1 – temperature C1 [0.01°C]
8. tmpE1t0 – temperature E1-0 [0.01°C]
9. tmpE1t1 – temperature E1-1 [0.01°C]
10. tmpE1t2 – temperature E1-2 [0.01°C]
11. tmpE1t3 – temperature E1-3 [0.01°C]
12. tmpE2t0 – temperature E2-0 [0.01°C]
13. tmpE2t1 – temperature E2-1 [0.01°C]
14. tmpE2t2 – temperature E2-2 [0.01°C]
15. tmpE2t3 – temperature E2-3 [0.01°C]
16. tmpEi0 – temperature Ei-0 [°C]
17. tmpEi1 – temperature Ei-1 [°C]
18. presEi0 – pressure Ei-0 [bar]
19. presEi1 – pressure Ei-1 [bar]
Example of decoded AX.25 message beacon packet
1:Fm OK0BDT To CQ <UI R Pid=F0 Len=83> [02:32:33R] [AA] [+++++++]
BDSAT AX.25 test message for radio amateurs: Hello Space!
Example of CW data beacon
Every CW beacon (no matter if data or message beacon) stars with „DE ok0bdt = “ and ends with „ar“.
de ok0bdt = u5433r126t29p30 ar
1. Total uptime [min]
2. Reset number
3. Temp MCU [°C]
4. Temp Radio PA [°C]
u5433 = Uptime 5433 minutes r126 = 126 resets of radio t29 = 29 degree of Celsius on DL radio MCU p30 =
30 degree of Celsius on DL radio PA
Example of CW message beacon
de ok0bds = morse test from earth ar