Quantum and Evolution Series Installation and Operating Handbook
7-79
Options:
Set location
Select this mode if you want the modem to automatically calculate the
satellite round trip delay using coordinates that you enter for the modem
and satellite positions.
Set delay
Select this mode to enter fixed minimum and maximum satellite round trip
delay times.
Use GPS
This mode allows mobile Paired Carrier operation (for example, on ships)
allowing travel anywhere in the world without having to change location or
satellite delay information for Paired Carrier. Paired Carrier operation is
seamless regardless of changes in position. It assumes that there is a GPS
source attached to the modem via RS232. When this mode is selected, the
modem remote serial control port is configured into RS232 mode at 4800
baud. The modem will poll the serial port on a regular basis for the latest
GPS position and use this in the Paired Carrier control process. The
modem automatically selects two commonly used GPS protocols, namely,
GGA (GPS Fix Data) and GLL (Geographic position Latitude/Longtitude),
and will support whichever is available. It uses the GPS information to
calculate the minimum and maximum delays to satellite and updates these
if they need to change from their existing values.
Factory
default:
Set location
Description:
Allows the selection of the method for determining the satellite round trip
delay. This can be entered as a time delay or can be automatically
calculated from location information. It can also be calculated
automatically using information provided by a GPS system attached to
the modem (in this case it is still necessary to enter a position for the
satellite via the
Edit-Rx-Carrier-Advanced-PCMA
Location screens).
The delay is required in order for the
Paired Carrier
signal processing
algorithm to find a best match for its stored copy of the outgoing
transmitted signal with the composite return signal, in order to subtract
the unwanted near signal leaving just the far carrier. For the fastest
possible acquisition time, once Paired Carrier is working, it is
recommended that the actual measured satellite delay shown on the
Status-PCMA
screen is used (-/+0.5ms) to set the minimum and
maximum satellite delays.
Edit-Rx-Carrier-Advanced-PCMA Location Screens
When the
Round trip delay
method for
Paired Carrier
is set to
Location
then the following
screens are displayed in sequence.