U-Link TRx User Guide
Ref.
09-03-V1.0
p
4
A dual color light indicates the stae of the U-Link TRX :
•
Green when the data are received, and red when data are transmitted. Green light indicating data reception, shall
represent the activity on the serial link of the receiver, and the red light indicating data emission, shall represent RF
activity at the output of the transmitter.
•
Given that data are transmitted in a burst mode (every second), as a result the light shall flash at 1 second periodicity
or more if repeater mode is activated (2 seconds). Corresponding marking of the light shall indicate “TX-RX”.
Framing Modes
U-Link TRx proposes two modes of transmission described below.
Transparent Mode
In transparent mode, data transmitted on serial link are “rough” data without frame coding.
DSNP Mode
Data sent to the serial link must be the following:
Type Content
Length
Synchronization
block
Start of text
ASCII Character STX
1 char
Type of message
“C”,”P”,”R”,”T”,”X” char
1 char
Address
Station number in BCD
1 char
Length of message
Length of the message
1 or 2 char(s)
Cadence
Periodicity of the message in seconds
1 char
Message
Content of the message
N char
Checksum
Checksum
Sum of all the bytes of the message
2 char
End of text
ASCII Character ETX
1 char
For RTCM (type R) messages, the synchronization block and checksum is not transmitted to the GPS rover. Only the RTCM
message (content of the message) is sent to the GPS rover.
ON
ON
1 2
TX-RX
Green light
indicating data
reception
ON
ON
1 2
TX-RX
Red light
indicating data
emission
