Beacon Format

Scroll down past the first table for an example of data received.

Ex-Alta 1’s beacon is a standard Cubesat Space Protocol frame, running in mode 2 of the second generation Gomspace radio, named AX100.

The first 4 bytes of the beacon are the attached sync marker for the AX100. Next is 4 bytes of CSP header as described here:

https://en.wikipedia.org/wiki/Cubesat_Space_Protocol

The rest of the beacon is power supply data and error correction trailers for RS-232.

The following table contains the beacon format for Ex-Alta 1. For most of the entries, no math is required. The units are listed in the Data column.

Name Type Bit Offset Data
Vboost[0] uint16_t 0 Boost converter voltage in mV
Vboost[1] uint16_t 16 Boost converter voltage in mV
Vboost[2] uint16_t 32 Boost converter voltage in mV
vbatt uint16_t 48 Battery voltage in mV
Curin[0] uint16_t 64 PV current in mA
Curin[1] uint16_t 80 PV current in mA
Curin[2] uint16_t 96 PV current in mA
cursun uint16_t 112 Total sun input current to battery in mA
cursys uint16_t 128 Total current out of battery in mA
reserved uint16_t 144 N/A
Curout[0] uint16_t 160 ADCS current in mA
Curout[1] uint16_t 176 Payload current in mA
Curout[2] uint16_t 192 Radio current in mA
Curout[3] uint16_t 208 ADCS current in mA
Curout[4] uint16_t 224 GPS current in mA
Curout[5] uint16_t 240 OBC current in mA
Output[0] uint8_t 256 Status of output
Output[1] uint8_t 264 Status of output
Output[2] uint8_t 272 Status of output
Output[3] uint8_t 280 Status of output
Output[4] uint8_t 288 Status of output
Output[5] uint8_t 296 Status of output
Output[6] uint8_t 304 Status of output
Output[7] uint8_t 312 Status of output
output_on_delta[0] uint16_t 320 Switch power on delay in s
output_on_delta[1] uint16_t 336 Switch power on delay in s
output_on_delta[2] uint16_t 352 Switch power on delay in s
output_on_delta[3] uint16_t 368 Switch power on delay in s
output_on_delta[4] uint16_t 384 Switch power on delay in s
output_on_delta[5] uint16_t 400 Switch power on delay in s
output_on_delta[6] uint16_t 416 Switch power on delay in s
output_on_delta[7] uint16_t 432 Switch power on delay in s
output_off_delta[0] uint16_t 448 Switch power off delay in s
output_off_delta[1] uint16_t 464 Switch power off delay in s
output_off_delta[2] uint16_t 480 Switch power off delay in s
output_off_delta[3] uint16_t 496 Switch power off delay in s
output_off_delta[4] uint16_t 512 Switch power off delay in s
output_off_delta[5] uint16_t 528 Switch power off delay in s
output_off_delta[6] uint16_t 544 Switch power off delay in s
output_off_delta[7] uint16_t 560 Switch power off delay in s
Latchup[0] uint16_t 576 Number of latchup resets on switch
Latchup[1] uint16_t 592 Number of latchup resets on switch
Latchup[2] uint16_t 608 Number of latchup resets on switch
Latchup[3] uint16_t 624 Number of latchup resets on switch
Latchup[4] uint16_t 640 Number of latchup resets on switch
Latchup[5] uint16_t 656 Number of latchup resets on switch
wdt_i2c_time_left uint32_t 672 Time left for I2C Watchdog timeout in s
wdt_gnd_time_left uint32_t 704 Time left for Ground Watchdog timeout in s
wdt_csp_pings_left[0] uint8_t 736 Pings left on CSP watchdog before reboot
wdt_csp_pings_left[1] uint8_t 744 Pings left on CSP watchdog before reboot
counter_wdt_i2c uint32_t 752 Number of reboots from I2C Watchdog
counter_wdt_gnd uint32_t 784 Number of reboots from Ground Watchdog
counter_wdt_csp[0] uint32_t 816 Number of reboots on CSP Watchdog
counter_wdt_csp[1] uint32_t 848 Number of reboots on CSP Watchdog
counter_boot uint32_t 880 Boot counter of EPS board
Temp[0] int16_t 912 Board temperature in C (Converter 1)
Temp[1] int16_t 928 Board temperature in C (Outputs)
Temp[2] int16_t 944 Board temperature in C (Converter 3)
Temp[3] int16_t 960 Board temperature in C (Middle of Board)
Temp[4] int16_t 976 Battery temperature in C (Cells 1 and 2)
Temp[5] int16_t 992 Battery temperature in C (Cells 3 and 4)
bootcause uint8_t 1008 Cause of boot
battmode uint8_t 1016 Battery mode (1-4 from empty to full)
pptmode uint8_t 1024 PPT mode (1 is MPPT, 2 is Fixed)
reserved uint16_t 1032 N/A
satellite_mode uint8_t 1048 Satellite in science mode (1) or safe mode (0)
comm_temp int16_t 1056 Radio temperature in C*10
Callsign[0] uint8_t 1064 O (ascii 0x4F)
Callsign[1] uint8_t 1072 N (ascii 0x4E)
Callsign[2] uint8_t 1080 0 (ascii 0x30)
Callsign[3] uint8_t 1088 3 (ascii 0x33)
Callsign[4] uint8_t 1096 C (ascii 0x43)
Callsign[5] uint8_t 1104 A (ascii 0x41)

 

 

 

Latest beacon from Ex-Alta 1.  Last updated May 31, 2017.

Name Value Data
Vboost[0] 447 Boost converter voltage in mV
Vboost[1]  2366 Boost converter voltage in mV
Vboost[2]  426 Boost converter voltage in mV
vbatt 15964 Battery voltage in mV
Curin[0]  0 PV current in mA
Curin[1]  2 PV current in mA
Curin[2]  5 PV current in mA
cursun  5 Total sun input current to battery in mA
cursys  81 Total current out of battery in mA
reserved  0 N/A
Curout[0]  0 ADCS current in mA
Curout[1]  0 Payload current in mA
Curout[2]  58 Radio current in mA
Curout[3]  21 ADCS current in mA
Curout[4]  6 GPS current in mA
Curout[5]  135 OBC current in mA
Output[0]  1 Status of output
Output[1]  0 Status of output
Output[2]  1 Status of output
Output[3]  1 Status of output
Output[4]  0 Status of output
Output[5]  1 Status of output
Output[6]  0 Status of output
Output[7]  0 Status of output
output_on_delta[0]  0 Switch power on delay in s
output_on_delta[1]  0 Switch power on delay in s
output_on_delta[2]  0 Switch power on delay in s
output_on_delta[3]  0 Switch power on delay in s
output_on_delta[4]  0 Switch power on delay in s
output_on_delta[5]  0 Switch power on delay in s
output_on_delta[6]  0 Switch power on delay in s
output_on_delta[7]  0 Switch power on delay in s
output_off_delta[0]  0 Switch power off delay in s
output_off_delta[1]  0 Switch power off delay in s
output_off_delta[2]  0 Switch power off delay in s
output_off_delta[3]  0 Switch power off delay in s
output_off_delta[4]  0 Switch power off delay in s
output_off_delta[5]  0 Switch power off delay in s
output_off_delta[6]  0 Switch power off delay in s
output_off_delta[7]  0 Switch power off delay in s
Latchup[0]  0 Number of latchup resets on switch
Latchup[1]  0 Number of latchup resets on switch
Latchup[2]  0 Number of latchup resets on switch
Latchup[3]  0 Number of latchup resets on switch
Latchup[4]  0 Number of latchup resets on switch
Latchup[5]  0 Number of latchup resets on switch
wdt_i2c_time_left  7199 Time left for I2C Watchdog timeout in s
wdt_gnd_time_left  155645 Time left for Ground Watchdog timeout in s
wdt_csp_pings_left[0]  0 Pings left on CSP watchdog before reboot
wdt_csp_pings_left[1]  0 Pings left on CSP watchdog before reboot
counter_wdt_i2c  0 Number of reboots from I2C Watchdog
counter_wdt_gnd  0 Number of reboots from Ground Watchdog
counter_wdt_csp[0]  1 Number of reboots on CSP Watchdog
counter_wdt_csp[1]  1 Number of reboots on CSP Watchdog
counter_boot  1 Boot counter of EPS board
Temp[0]  32 Board temperature in C (Converter 1)
Temp[1]  25 Board temperature in C (Outputs)
Temp[2]  23 Board temperature in C (Converter 3)
Temp[3]  23 Board temperature in C (Middle of Board)
Temp[4]  18 Battery temperature in C (Cells 1 and 2)
Temp[5]  17 Battery temperature in C (Cells 3 and 4)
bootcause  7 Cause of boot
battmode  3 Battery mode (1-4 from empty to full)
pptmode  1 PPT mode (1 is MPPT, 2 is Fixed)
reserved  0 N/A
satellite_mode  1 Satellite in science mode (1) or safe mode (0)
comm_temp 24.6 Radio temperature C
Callsign[0] O O (ascii 0x4F)
Callsign[1] N N (ascii 0x4E)
Callsign[2] 0 0 (ascii 0x30)
Callsign[3] 3 3 (ascii 0x33)
Callsign[4] C C (ascii 0x43)
Callsign[5] A A (ascii 0x41)

 

 

 

Some of the first beacons sent were decoded by JA0CAW using an AX.25 decoder. Most of the packet is available from this despite the protocols being different.

 

Name Decimal Converted Data
Vboost[0] ??? ??? Boost converter voltage in mV
Vboost[1] ???  ??? Boost converter voltage in mV
Vboost[2] ???  ??? Boost converter voltage in mV
vbatt ??? ??? Battery voltage in mV
Curin[0] ???  ??? PV current in mA
Curin[1] ???  ??? PV current in mA
Curin[2] 45  45 PV current in mA
cursun 83  83 Total sun input current to battery in mA
cursys 81  81 Total current out of battery in mA
reserved 0  0 N/A
Curout[0] 0  0 ADCS current in mA
Curout[1] 0  0 Payload current in mA
Curout[2] 58  58 Radio current in mA
Curout[3] 19  19 ADCS current in mA
Curout[4] 6  6 GPS current in mA
Curout[5] 124  124 OBC current in mA
Output[0] 1  1 Status of output
Output[1] 0  0 Status of output
Output[2] 1  1 Status of output
Output[3] 1  1 Status of output
Output[4] 0  0 Status of output
Output[5] 1  1 Status of output
Output[6] 0  0 Status of output
Output[7] 0  0 Status of output
output_on_delta[0] 0  0 Switch power on delay in s
output_on_delta[1] 0  0 Switch power on delay in s
output_on_delta[2] 0  0 Switch power on delay in s
output_on_delta[3] 0  0 Switch power on delay in s
output_on_delta[4] 0  0 Switch power on delay in s
output_on_delta[5] 0  0 Switch power on delay in s
output_on_delta[6] 0  0 Switch power on delay in s
output_on_delta[7] 0  0 Switch power on delay in s
output_off_delta[0] 0  0 Switch power off delay in s
output_off_delta[1] 0  0 Switch power off delay in s
output_off_delta[2] 0  0 Switch power off delay in s
output_off_delta[3] 0  0 Switch power off delay in s
output_off_delta[4] 0  0 Switch power off delay in s
output_off_delta[5] 0  0 Switch power off delay in s
output_off_delta[6] 0  0 Switch power off delay in s
output_off_delta[7] 0  0 Switch power off delay in s
Latchup[0] 0  0 Number of latchup resets on switch
Latchup[1] 0  0 Number of latchup resets on switch
Latchup[2] 0  0 Number of latchup resets on switch
Latchup[3] 0  0 Number of latchup resets on switch
Latchup[4] 0  0 Number of latchup resets on switch
Latchup[5] 0  0 Number of latchup resets on switch
wdt_i2c_time_left 7199  7199 Time left for I2C Watchdog timeout in s
wdt_gnd_time_left 157720  157720 Time left for Ground Watchdog timeout in s
wdt_csp_pings_left[0] 5  5 Pings left on CSP watchdog before reboot
wdt_csp_pings_left[1] 5  5 Pings left on CSP watchdog before reboot
counter_wdt_i2c 0  0 Number of reboots from I2C Watchdog
counter_wdt_gnd 0  0 Number of reboots from Ground Watchdog
counter_wdt_csp[0] 0  0 Number of reboots on CSP Watchdog
counter_wdt_csp[1] 0  0 Number of reboots on CSP Watchdog
counter_boot 1  1 Boot counter of EPS board
Temp[0] 32  32 Board temperature in C (Converter 1)
Temp[1] 34  34 Board temperature in C (Outputs)
Temp[2] 31  31 Board temperature in C (Converter 3)
Temp[3] 31  31 Board temperature in C (Middle of Board)
Temp[4] 28  28 Battery temperature in C (Cells 1 and 2)
Temp[5] 28  28 Battery temperature in C (Cells 3 and 4)
bootcause 7  7 Cause of boot
battmode 4  4 Battery mode (1-4 from empty to full)
pptmode 1  1 PPT mode (1 is MPPT, 2 is Fixed)
reserved 0  0 N/A
satellite_mode 1  1 Satellite in science mode (1) or safe mode (0)
comm_temp 18433 18.433 Radio temperature in C*10
Callsign[0] 79 O O (ascii 0x4F)
Callsign[1] 78 N N (ascii 0x4E)
Callsign[2] 48 0 0 (ascii 0x30)
Callsign[3] 51 3 3 (ascii 0x33)
Callsign[4] 67 C C (ascii 0x43)
Callsign[5] 65 A A (ascii 0x41)

Share AlbertaSat

Like AlbertaSat? Share our project on Facebook and Twitter!