1. Neha Nehru Shadab Ambat
BEACON & TELEMETRY
Neha Nehru
Shadab Ambat

2. Objective
Periodically send current status information of the satellite to the ground station
Send satellite telemetry information upon user request

3. Requirements Beacon Data packet must be APRS compatible Telemetry
Must be sent periodically.
Telemetry
Must be KCOM encoded before transmission.
Data should be sent only upon user request.

4. Data Packets Beacon (34 bytes)- Digital Values Sequence Number
Byte No.
Data
Unit/Label 1
Data type identifier T 2 3 6
Sequence Number
Hash
Sequence No.
Delimiter # , 7 10
Analog Values
Solar Cell voltage mV 11 14
Solar Cell Current mA 15 18
Battery Voltage 19 22
Battery Temp.
mdegC 23 26
Processor Temp. 27
Digital Values
Solar Cell Channel 2
Digital Values(1/0)
1-true
0-false 28
Solar Cell Channel 1 29
Solar Cell Channel 0 30
Audio File Played 31
Picture Taken 32
Autonomously Executed Commands 33
Battery Charger On 34
Battery Heater On

5. Data Packets Telemetry Packet 1 (42 bytes)- Hard State Data
Byte No.
Data
Unit/Label 1 3 5
Hard State Data
Solar Cell Vtg 1
Solar Cell Vtg 2
Solar Cell
Vtg 3 mV 7 9 11
Solar Cell Vtg 4
Solar Cell Vtg 5
Vtg 6 13 15 17
Current 1
Current 2
Current3 mA 19 21 23
Current 5
Current 6
Bus Vtg1 25 27 29
Bus Vtg2
Bus
Current2 31 33 35
Soft State Data
Rx VHF packets
Sent UHF Packets
DTMF
Command Rx 37 39
Rx S-band Packets
Sent S-band Packets

6. Battery Heater Duty Cycle No. of Autonomously Executed Commands
Data Packets
Telemetry Packet 2 (40 bytes)-
Byte No.
Data
Unit/Label 1 3 5
Hard State Data
Solar Cell Temp 1
Solar Cell Temp 2
Solar Cell
Temp 3
mDeg C
mDegC 7 9 11
Solar Cell Temp 4
Solar Cell Temp 5
Temp 6 13 15 17
Sec Battery
Voltage
Sec Battery
Temp
Charger Current mV mA 19 21
Camera Temp
VHF Current 23 25
UHF Current
Processor Temp 27 29 31
Soft State Data
Audio Files Played
CW Beacons Sent
Digibeacons Sent 33 35 37
Seconds Passed
Pictures Taken
Battery Heater Duty Cycle 39
No. of Autonomously Executed Commands

7. Design

8. Code
Beacon
Input array structure consists of 5 Analog values and an 8-bit Digital value
Functions/Macros
void BeaconTask(void); // Beacon Task
TRY_BCN_PERIOD(unsigned char* period /* Minutes */, unsigned char bcn_interval /* OSTicks */);
Waits for a beacon period. Period automatically set to new value if command received from Command_Parse
send_tx_bcn(unsigned char *data, unsigned char num_bytes);
Sends packet to Packet_Tx for transmission
void toAsciiDigit(unsigned int value, ubyte *packet_index;
Takes the desired value that is to be converted to ASCII (sequence number/analog values/digital values) and the beacon packet index as arguments
Extracts each digit and converts it to ASCII.
Each value is converted to ASCII
Delimiters (,) are added to distinguish different fields
Sequence nos. incremented for each packet
Sends final APRS encoded packet to Packet_Tx for transmission

9. Code Telemetry Defined by 2 packet types Functions/Macros
void TelemetryTask(void); // Telemetry Task
GET_TLM_CMD(unsigned char* cmd, unsigned char* data, unsigned char* num_bytes);
Waits until TELEMETRY_REQUEST command received from Command_Parse
*data specifies the packet type (Packet1 or Packet2)
send_tx_raw( unsigned char cmd, unsigned char* data, unsigned char num_bytes );
Sends raw unencoded packet to Packet_Tx for KCOM encoding and transmission

10. Code Array Manager Functions/Macros
Allows other tasks to read/write values from the Beacon and Telemetry memory array
Functions/Macros
ubyte SetBcnArray(ubyte field, ubyte arg, ubyte value);
Sets specified field in the memory array to value
arg used to supply additional information (channel no., bit position etc.)
ubyte GetBcnArray (ubyte *bcn_ptr, ubyte field, ubyte bcn_arg);
Gets value corresponding to the specified field
Stores the value to *bcn_ptr
ubyte SetTlmArray (ubyte field, ubyte tlm_arg, uint16 value);
Similar to SetBcnArray except value is a 2 byte unsigned int
ubyte GetTlmArray (uint16 *tlm_ptr, ubyte field, ubyte tlm_arg);
Similar to GetBcnArray except tlm_ptr is an unsigned int instead of a ubyte

11. Testing Packet format and com link tested
Debugging mainly done using the library function kysat_printf to compare the packet formats to the required one

12. Goals in Progress Status Goals Achieved
Beacon packet format and com link between Beacon and Packet_TX functioning.
Com link between Telemetry and Packet_TX tested and working.
Com link between Command_Parse and Telemetry tested and working.
Goals in Progress
Functions for the Array Manager nearly complete(untested)
RTCGetTime function and TRY_BCN_PERIOD still to be tested.