SANOSAT-1 [NEPAL-PQ1] Communication Protocols

SanoSat-1 transmits in CW Morse, RTTY-FSK and GFSK schemes. Downlink can be done in all three schemes whereas the uplink can only be done in GFSK Modulation within the protocol defined below.

CW BEACON TRANSMISSION  

SanoSat-1 transmits CW Beacon with Call sign and the general health parameters of the satellite. It can also be used to detect the presence of the satellite, measure basic properties of the satellite such as strength, fading, Doppler speed, etc.

The satellite transmits temperature of the communication module in degree Celsius, temperature of the battery in degree Celsius, charging current in mA, battery voltage per 10mV and antenna deployment status.

Speed: 20WPM

The Transmission Protocol is as follows:

AM9NPQXXXYYYZZZ112?33

XXX: Temperature of the communication board.The length and the sign can be calculated from the residue.

YYY: Temperature of the Battery board.The length and the sign can be calculated from the residue.

ZZZ: Charging current in mA. The length can be calculated from the residue.

11: Battery voltage per 10 mV. i.e. 3.7V is represented by 37.

 2: Residue containing the length for battery temperature, current, signs for the temperatures, and the deployment status. The figure below describes the arrangement in residue.

?: Delimiter to separate data from NMEA checksum.

33: NMEA checksum calculated over XXXYYYZZZ112

Table 1 : CW Beacon Transmission Protocol

S.N. Type Length Data Type Value Remarks
1. Call Sign 6 ASCII AM9NPQ  
2. Temperature COM 2-3 INT   Calculate the Integer
3. Temperature Battery 2-3 INT   Calculate the Integer
3. Current mA 2-3 INT   Calculate the Integer
4. VBat /10 V 2 INT   Calculate the Integer
5. Residuals 2 HEX    
6. Delimiter 1 ASCII ?  
7. NMEA Checksum 2 HEX   Calculated over the data i.e. except the call sign

Example for CW Beacon Transmission: AM9NPQ373003506?37

S.N. Type Length Example
1. Call Sign 6 AM9NPQ
2. Temperature COM 2 37
3. Temperature Battery 2 30
3. Current mA 1 0
4. VBat /10 V 2 35
5. Residuals 2 06
6. Delimiter 1 ?
7. NMEA Checksum 2 37

RTTY-FSK TRANSMISSION

SanoSat-1 transmits Radio-Teletype FSK in ASCII-8 Mode. It transmits Call sign, battery temperature, charging current, battery voltage, no of resets, deployment status and the radiation intensity.

The settings for RTTY FSK reception are as follows:

Mode: ASCII-8

Speed: 45 Baud

Shift: 425 Hz

Separated by Commas

The transmission protocol is as follow:

CALL_SIGN, TBAT, ICHG, VBAT, NOR, DEP, RAD

CALL_SIGN: AM9NPQ

TBAT: Battery temperature in Celsius.

ICHG: Charging current in mA.

VBAT: Battery voltage in mV.

NOR: Number of resets.

DEP: Antenna deployment status.

RAD: Radiation intensity in uSv/hr.

Table 2 : RTTY FSK transmission protocol

S.N. Type Data Type Remarks
  Call Sign ASCII  
  Temperature BAT INT Degree Celcuis
  Current mA INT mA
  VBat mV INT mV
  No of Resets INT Calculate the Integer
  Deployment Status INT Deployed/Not Deployed
  Radiation Intensity INT uSv/hr

Example: AM9NPQ,12,230,392,123,1,10

S.N. Type Value Remarks
  Call Sign AM9NPQ  
  Temperature BAT 12 Degree Celcuis
  Current mA 230 mA
  VBat mV 392 mV
  No of Resets 123 Calculate the Integer
  Deployment Status 1 Deployed/Not Deployed
  Radiation Intensity 10 uSv/hr

GFSK Transmission

SanoSat-1 uses GFSK modulation scheme to transmit the telemetry and in digipeater mode.

The settings for the GFSK modulation scheme are as follows:

Deviation: 1 kHz

Speed: 500 bps

Si4463 Packet Protocol

CRC: CRC CCIT

The GFSK transmission uses Si446x’s default packet structure. Preamble and sync are always sent LSB first according to the Si446x’s packet format.

Table 3 represents the packet structure for both telemetry and digipeater packets.

Table 3 : GFSK packet structure

S.N. Type Size Value
  Preamble 4 bytes 4 bytes of alternating 0s and 1s (55 55 55 55) sent LSB first. (AA AA AA AA, if received as MSB first)
  Sync Word 2 Bytes 2D D4 send LSB first. (B4 2B, if received as MSB first)
  Message Length (Field 1) 1 Bytes Length Message including CRC1+Message+CRC2  (MSB first)
  CRC1 2 Bytes CRC of Message Length (MSB first)
  Header/Flag 4 Bytes 0xFFFF and 0x0000 (MSB first)
  Message 1 to 126 Bytes Data (MSB first)
  CRC2 2 Bytes Computed on Message length, 0xFFFF, 0x0000 and Data (MSB first)

CRC scheme = CRC CCIT with initial value 0xFFFF

1.   Message Breakdown for Telemetry (Packet Type=0001)

Message from Table 3 is further divided according to Table 4 for telemetry packets.

Table 4 : Message structure for Telemetry Packet

S.N. Type Size Value
  Call Sign 6 Bytes AM9NPQ
  Packet Type 2 Bytes 0x0001
  COM Temperature 2 Bytes  
  Charging Voltage mV 2 Bytes  
  Charging Current mA 2 Bytes  
  Battery Temperature 2 Bytes  
  Radiation uSv/hr 2 Bytes  
  No of Resets 2 Bytes  
  Antenna Deployment Status 1 Byte 0x00 or 0xFF
  Total 21  

Total No of Bytes including preamble, sync, message, header and CRC: 36

Total No of Bytes for Message in Telemetry Packet: 21

Example

S.N. Type Value (HEX) Value (Decimal /ASCII) Explanation
  Preamble AA AA AA AA   (55555555 sent LSB first)
  Sync B4 2B   (2DD4 sent LSB first)
  Length 19 25 (INT) Length of CRC1+Data+CRC2
  CRC 1 E8 62   CRC CCIT of 19 is 62E8
  Delimiter FF FF 00 00    
  Call Sign 41 4D 39 4E 50 51 AM9NPQ (ASCII) AM9NPQ
  Packet Type 01 00 1 (INT) Telemetry Packet (Decimal of 00 01)
  COM Temperature 20 00 32 (INT) Decimal of (00 20)
  Battery Voltage mV 54 01 340 (INT) Decimal of (01 54)
  Charging Current mA 40 01 320 (INT) Decimal of (01 40)
  Battery Temperature 1E 00 30 (INT) Decimal of (00 1E)
  Radiation Level uSv/hr 0c 00 12 (INT) Decimal of (00 0C)
  No of Resets 33 00 51 (INT) Decimal of (00 33)
  Antenna Deployment Status 01 1 (BOL) Decimal
  CRC 2 9B A0   CRC CCIT of 19FFFF0000414D394E5051010 02000540140011E000C00330001 is A0 9B

2.   Message Breakdown for Digipeater Packets (Packet Type=0001)

Message from Table 3 is further divided according to Table 5 for digipeater packets.

For digipeater packets,

Table 5 : Message structure for digipeater packets

S.N. Type Size Value
  Header 6 Bytes 4E 50 51 (NPQ in ASCII)
  Data 0-120 Bytes  
  Total 1-126 Bytes  

Total No of Bytes including preamble, sync, message, header and CRC: 16-141 Bytes

Total No of Bytes for Message in Telemetry Packet: 1-126 Bytes

Example

S.N. Type Value (HEX) Value (Decimal /ASCII) Explanation
  Preamble AA AA AA AA   (55555555 sent LSB first)
  Sync B4 2B   (2DD4 sent LSB first)
  Length 1B 27 (INT) Length of CRC1+Data+CRC2
  CRC 1 AA 42   CRC CCIT of 1B is 42AA
  Delimiter FF FF 00 00    
  Data 44 49 47 49 50 45 41 54 45 52 20 54 45 53 54 20 53 41 4E 4F 53 41 54 DIGIPEATER TEST SANOSAT  
  CRC 2 FC C8   CRC CCIT of 1BFFFF0000444947 49504541544552205445535420 53414E4F534154  is C8 FC

TIMING PERIOD

Updating Soon……

Leave a Reply