User's Manual

19 | Page
Proprietary and Confidential Revised 10-11-11
SXL1. Each message below describes the payload region of the satellite burst message. The
network protocol is removed from this description for clarity. Network operators utilizing the resulting
internet packets must refer to Globalstar documentation regarding Simplex Data Service use.
All on-air SXL1 messages follow the payload format depicted below. Because the satellite packet is
restricted to 9 bytes total, the message fields are used sparingly. The first byte of every on-air
message contains the message type identifier. The message type identifier is the least significant 2
bits of the first byte of data. The SXL1 may emit the following 4 types of on-air messages:
On-Air Message Type Definition
Message Type (5
LSbits of first byte)
Message Payload Content
11001011 (0xCB) Location Message (contains GPS location data)
11001111 (0xCF) Remote Message
11010011 (0xD3) Termination Message
11010111 (0xD7) Engineering Message
The least two significant bits are set to 0x11 with the upper six bits constrained to a range of 0x32 to
0x35 to avoid conflict with other satellite transmitters that use a similar on-air protocol.
The subsequent 8 bytes are encoded as described below depending on the message type. For data
fields that span multiple bytes, the parameters are sent most significant byte first, most significant bit
first in each byte.
Location Message Format
The SXL1 transmits location data using the Location Messaging format. The Location Message is
denoted as message type 0xCB and will follow the format:
Location Message Format
Byte Bits Description
0xCB = Message Type 8 Bit 7:0 = 0xCB = SXL1 Location message type:
Latitude / Longitude 48 Byte 1 = Latitude MSByte
Byte 2 = Latitude
Byte 3 = Latitude LSByte
Byte 4 = Longitude MSByte
Byte 5 = Longitude
Byte 6 = Longitude LSByte
(see section 2.3.1 and 2.3.2 for encoding method)
Status 16 Bit 2:0 = battery status
Bit 3 = 0 = standard interval report, 1= subsequent interval report
Bit 4 = alarm (0=no alarm, 1=alarm w/ cause defined)
Bit 8:5 = message cause (valid when Bit 4 = 1)
Bit 9 = 1= engine run-time data is in message cause field
Bit 10 = configuration change (toggles)
Bits 13:11 = message count (modulo 7 count)
Bit 14 = motion state, 0 = unit is stationary, 1 = unit in motion
Bit 15 = 0=3D GPS Fix found, 1=2D GPS Fix found
Message Type (Byte 1)
The SXL1 standard location message shows 0xCB in the first byte denoting a standard location
message.