For radio amateurs
BDSat HAM info

Basic information for

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 [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]/li>
• 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 [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 [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 [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