Satellite Blog @JE9PEL

Reference URL:
https://community.libre.space/t/isro-sslv-d3-2024-08-16-03-47-utc/11876/50

Little-endian order:
https://www.asahi-net.or.jp/~ei7m-wkt/numb1146.htm
https://www.ne.jp/asahi/hamradio/je9pel/stratsat.htm

1. Free login this site, https://chatgpt.com/ as Google account.

2. On the "Message ChatGPT" line at the bottom, simply paste in the ENTIRE instruction below:

   struct satellite_info {
    char call_sign[6];
    uint16_t frame_number;
    uint8_t message_type;
    uint8_t transmission_power;
    unsigned long satellite_unix_time;
    int16_t obc_temperature; 
    int16_t battery_temperature;
    int16_t external_temperature;
    int16_t base_plate_temperature;
    int16_t solar_panel_temperature;
    int16_t radiation;
    uint16_t bus_voltage; 
    int16_t bus_current; 
    uint16_t battery_maximum_capacity; 
    uint16_t battery_remaining_capacity; 
    uint16_t solar_bus_voltage;
    uint16_t solar_bus_current; 
    uint16_t boot_counter;
    uint8_t checksum; 
   };

3. … after that, paste in HEX decodes on the "Message ChatGPT" line at the bottom:

   53 52 30 53 41 54 FC 19 01 00 24 B4 C1 66 A4 00 E5 00 F6 FF 71 00 45 00 B8 01 23 10 DC FF 7A 0A 03 0C 2C 10 24 00 01 00 17

4. Watch the parsing of the data flow up the screen:

   53 52 30 53 41 54 -> "SR0SAT"

   Frame Number (uint16_t frame_number):
   FC 19 -> 0x19FC (hex) -> 6652 (decimal)

   Message Type (uint8_t message_type):
   01 -> 1
 
   Transmission Power (uint8_t transmission_power):
   00 -> 0 (100 mW)

   Satellite Unix Time (unsigned long satellite_unix_time):
   24 B4 C1 66 -> 0x66C1B424 (hex) -> 1724081700 (decimal)

   OBC Temperature (int16_t obc_temperature):
   A4 00 -> 0x00A4 (hex) -> 164 (divided by 10) ->  16.4°C

   Battery Temperature (int16_t battery_temperature):
   E5 00 -> 0x00E5 (hex) -> 229 (divided by 10) ->  22.9°C

   External Temperature (int16_t external_temperature):
   F6 FF -> 0xFFF6 (hex) -> -10 (divided by 10) -> -1.0°C

   Base Plate Temperature (int16_t base_plate_temperature):
   71 00 -> 0x0071 (hex) -> 113 (divided by 10) -> 11.3°C

   Solar Panel Temperature (int16_t solar_panel_temperature):
   45 00 -> 0x0045 (hex) -> 69 (divided by 10) -> 6.9°C

   Radiation (int16_t radiation):
   B8 01 -> 0x01B8 (hex) -> 440 (divided by 100) -> 4.4 µSv/h
 
   Bus Voltage (uint16_t bus_voltage):
   23 10 -> 0x1023 (hex) -> 4131 mV

   Bus Current (int16_t bus_current):
   DC FF -> 0xFFDC (hex) -> -36 (divided by 1000) -> -0.036 mA

   Battery Maximum Capacity (uint16_t battery_maximum_capacity):
   7A 0A -> 0x0A7A (hex) -> 2682 mAh
 
   Battery Remaining Capacity (uint16_t battery_remaining_capacity):
   03 0C -> 0x0C03 (hex) -> 3075 mAh

   Solar Bus Voltage (uint16_t solar_bus_voltage):
   2C 10 -> 0x102C (hex) -> 4140 (divided by 1000) -> 4.140 V

   Solar Bus Current (uint16_t solar_bus_current):
   24 00 -> 0x0024 (hex) -> 36 mA

   Boot Counter (uint16_t boot_counter):
   01 00 -> 0x0001 (hex) -> 1
 
   Checksum (uint8_t checksum):
   17 -> 23

   Summary of Decoded Data:
   Call Sign: SR0SAT
   Frame Number: 6652
   Message Type: 1
   Transmission Power: 100 mW
   Satellite Unix Time: 1724081700
   OBC Temperature: 16.4°C
   Battery Temperature: 22.9°C
   External Temperature: -1.0°C
   Base Plate Temperature: 11.3°C
   Solar Panel Temperature: 6.9°C
   Radiation: 4.4 µSv/h
   Bus Voltage: 4131 mV
   Bus Current: -0.036 mA
   Battery Maximum Capacity: 2682 mAh
   Battery Remaining Capacity: 3075 mAh
   Solar Bus Voltage: 4.140 V
   Solar Bus Current: 36 mA
   Boot Counter: 1
   Checksum: 23

Wrote by PY4ZBZ:
I discovered mistakes that the SR-0 DemoSAT's ChatGPT decoder always
makes: Unix time and Frame number are always decoded wrongly, as the
example shows for Unix Time. (certo=OK, errado=error)

The SatNOGS Dashboard decodes correctly,
as Unix time 5B FF CA 66 (little endian) is worth 66CAFF5B(hex)=
1724579675(dec)=2024-08-25 09:54:35 GMT (06:54:35 localtime=GMT-3):