Vypočujte si vysielanie novej českej družice BDSat-2

SOSA

V poradí dvanásta česká družica vyštartovala do vesmíru v rámci misie Transporter 6 na palube rakety Falcon 9 z americkej Floridy 3. januára 2023. Jednalo sa vôbec o prvý vesmírny štart v novom roku.

Družica BDSat-2 je technologická misia, ktorá má za úlohu otestovať vo vesmíre nové technológie. Na palube sa nachádzajú tlakové senzory a banka superkapacitorov, ktorá by v budúcnosti mohla počas kozmických misií nahradiť v určitých konkrétnych prípadoch klasické akumulátory. Za projektom stojí firma BD SENSORS, s.r.o. a ďalší partneri, napríklad aj pôvodom slovenská firma Spacemanic, ktorá v súčasnosti pôsobí práve v Českej republike. Viac informácií o projekte a partneroch projektu sa dozviete na stránkach www.bdsat.cz

BDSat-2 vysiela na rádioamatérskych frekvenciách a záujemcovia môžu skúsiť zachytiť signály z tejto družice. Prinášame preto kompletné informácie o použitých frekvenciách a režimoch vysielania tejto novej družice.

Informácie pre rádioamatérov

  • Callsign: OK0BDT
  • 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

PACLEN 255
TXDELAY 15
MYCALL [Your call sign]
UNPROTO CQ (or callsign)

Orbital parameters / Preliminary TLE

Orbit: 550km SSO
TLE: https://db.satnogs.org/satellite/NJFB-9884-9643-7739-4519#data (bottom of the page)

Message types

  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] [+++++++]
U,90957,4149444,64,1,2080,2459,2437,0,,5,91170,89,105

Explanation:

  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] [+++++++]
OBC,25,95248,3483332,8308,1994,1994,nan,1906,1893,1881,1900,657

Explanation:

  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] [+++++++]
PSU,52,95625,4278000,8333,2346,1877,214,139,7f,1,0

Explanation:

  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] [+++++++]
BDS,-1,-1,11,0,1881,1900,1906,1906,1937,1925,1925,1931,1956,1937,16.55,7246481.00,1.007,16.000

Explanation:

  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

Explanation:

  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