ARGOS (ARTIC R2) Satellite Communication Guide

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Contributors: PaulZC
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ARGOS Message Formats

The table below summarizes the properties of each ARGOS message format as supported by the ARTIC R2:

Message FormatModeData Rate

(bits/sec) #

Min Length

(bits) *

Max Length

(bits) *

Notes
A2ARGOS-240052276
A3ARGOS-340052276
ZEARGOS-34002828
A3 HDARGOS-34800604636HD = High Data rate
A4 HDARGOS-448009924960HD = High Data rate
A4 MDARGOS-41200480960MD = Medium Data rate
A4 VLDARGOS-42002884VLD = Very Low Data rate

# The data bit rate quoted in the table is the bit rate before convolutional encoding (where used)

* The message lengths quoted in the table include the 28-bit Platform ID but exclude the message length identifier or any required tail bits. The ARTIC R2 always calculates and transmits the FEC for A3 HD and the FCS for A4 HD/MD. The quoted maximum message lengths exclude the FEC/FCS.

The ARGOS-4 VLD mode is exciting since the uplink can use much lower transmit power (100mW or even less) compared to the other modes. The message are short, including only the 28-bit Platform ID, or the Platform ID plus 56 bits of user data. However, 56-bits is enough to encode GNSS position (latitude and longitude) to 4 decimal places and accurate to ±5.55m at the equator.

ARGOS-3 ZE and ARGOS-4 VLD (Short) messages contain only the 28-bit Platform ID. ARGOS is still able to calculate the position of the transmitter using Doppler location.

If you want to dig further into the message formats and encoding schemes, they are defined in the CNES Physical Layer Requirements:

Message FormatCNES Physical Layer Requirements
A2AS3-SP-516-2098-CNES
A3 + ZEAS3-SP-516-274-CNES
A3 HDAS3-SP-516-273-CNES
A4 HD/MDA4-SS-TER-SP-0078-CNES
A4 VLDA4-SS-TER-SP-0079-CNES

Don't Panic! Our ARGOS ARTIC R2 Arduino Library does all of the message encoding for you!