Overview
The stabilized or in-motion antenna provides a monitoring SOTM (Satellite-
On-the-Move) platform. Gilat SkyEdgeII modem (VSAT) provides highly
reliable network communication means. This document proposes that these
early mentioned systems generate two-channel interfacing loosely based on
the NMEA 0183 data protocol. The interfacing occurs via RS232 serial port at
9600-N-8-1 baud without any authentication or encryption in the link. To
enable interfacing, it is not required to log in to the SkyEdgeII system (none
security settings are implemented within it).
This document describes the command - response sequence between the
antenna and Gilat SkyEdgeII modem (VSAT).
Generic Antenna Protocol Format
All data in the Generic Antenna protocol are transmitted in the form of
messages. Only printable ASCII characters and CR (carriage return) and LF
(line feed) are allowed. Each message starts with a "$" sign and ends with
<CR><LF>.
The general format of a sentence is: $ttsss,d1,d2,....<CR><LF>.
The first two characters "tt", following the "$", are the talker identifiers. The
next three characters "sss" are the message identifiers. The "sss" characters
are followed by a number of data fields (separated by commas), mandatory
checksum, and terminated by carriage return and line feed. The data fields
are uniquely defined for each message type.
A message may contain up to 80 characters, the "$" and CR/LF signs. If data
for a field are not available, the field is omitted, but the delimiting commas
still appear, with no space between them.
The checksum field consists of a "*" sign and two hex digits representing the
exclusive OR (XOR) of all characters in-between, but not including the "$"
and "*" signs.
