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

4. Beacon Data Packet (34 bytes)
Byte No
Data
Unit/Label
Bytes 1
Data type identifier T 2
Sequence
Number
Hash # 3
Sequence No. 6
Delimiter , 7
Analog
Values
Solar Cell Voltage mV 10 11
Solar Cell Current mA 14 15
Battery Voltage 18 19
Battery Temp.
DegC 22 23
Processor Temp. 26 27
Digital
Solar Cell Channel 2
Values(1/0)
1-true
0-false 8 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. Telemetry Data Packet 1 (42 bytes)
Byte No
Data
Unit/Label
Bytes 1
Hard State Data
Solar Cell Voltage 1 mV 2 3
Solar Cell Voltage 2 5
Solar Cell Voltage 3 7
Solar Cell Voltage 4 9
Solar Cell Voltage 5 11
Solar Cell Voltage 6 13
Solar Cell Current 1 mA 15
Solar Cell Current 2 17
Solar Cell Current 3 19
Solar Cell Current 5 21
Solar Cell Current 6 23
Bus Voltage 1 25
Bus Voltage 2 27
Bus Current 1 29
Bus Current 2 31
Soft State Data
Rx VHF packets 33
Sent UHF Packets 35
DTMF
Command Rx 38
Rx S-band Packets 41
Sent S-band Packets

6. Telemetry Data Packet 2 (40 bytes)
Byte No
Data
Unit/Label
Bytes 1
Hard State Data
Solar Cell Temp 1
DegC 2 3
Solar Cell Temp 2 5
Solar Cell Temp 3 7
Solar Cell Temp 4 9
Solar Cell Temp 5 11
Solar Cell Temp 6 13
Sec Battery
Voltage mV 15
Temp 17
Charger Current mA 19
Camera Temp 21
VHF Current 23
UHF Current 25
Processor temp 27
Soft State Data
Audio Files Played 29
CW Beacons Sent 31
Digibeacons Sent 33
Seconds Passed 35
Pictures Taken 37
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
Allows other tasks to read/write values from the Beacon and Telemetry memory arrays
Functions/Macros
ubyte SetBcnArray(ubyte field, ubyte *value);
Sets specified field to *value in Beacon memory array
Can either set individual fields in the buffer or the entire array in one function call using BLOCK_SET.
Returns UPDATE_NOERR if update successful else returns UPDATE_ERR
ubyte GetBcnArray (ubyte field, ubyte *bcn_ptr);
Gets the current value of the corresponding field from the Beacon memory buffer
Stores it to the address specified by the user (bcn_ptr)
Option of getting a single field or the entire memory array (BLOCK_TRANSFER)
Returns TRANSFER_NOERR on success else returns TRANSFER_ERR
ubyte SetTlmArray (ubyte field, int *value);
Similar to SetBcnArray except *value is a 2 byte integer. Used to set fields in global Telemetry buffer
ubyte GetTlmArray (ubyte field, int *tlm_ptr);
Telemetry counterpart of GetBcnArray. Difference - *tlm_ptr is an int instead of a ubyte

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

12. Future Goals 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.
Functions for the Array_Manager complete (untested)
Future Goals
RTCGetTime function from Cmd_Parse still needs to be tested.
Need to test if Array_Manager functions working correctly