Vemco VR100 - VR100 GPS Functionality

VEMCO – VR100 Manual 28 May 2018 68
6.8 GPS
The GPS (Global Positioning System) works by coordinating position information from multiple satellites. It
needs to see three satellites to get a good position fix. Once it sees even one satellite, it can download an
almanac from that satellite to get an idea of where to expect other satellites to be located, and therefore get its
three satellites faster.
On the VR100 receiver screen, when the GPS is locked and getting position fixes then the longitude and
latitude will be displayed on the second line of the main menu, in decimal degrees:
XX.XXXXXA XXX.XXXXXB
where X is a digit (0-9), A is N (North) or S (South), and B is E (East) or W (West).
When the VR100 is not locked, the GPS message displayed will be one of those listed in the table below.
The status of the GPS is updated every 5 seconds.
GPS Status Messages
Display
Meaning
Getting Fix
GPS is searching for satellites. The GPS must see at least 3
satellites for a minimum of 15 seconds to begin giving position
fixes.
High PDOP
GPS sees at least 3 satellites, but cannot get a fix because satellite
PDOP is too high. This indicates the satellites in view are not
positioned well enough to provide a reliable fix.
Rcvr Fault
GPS Antenna is broken; report to VEMCO for instructions
IMPORTANT
The VR100 internal GPS is designed to provide accurate time sync data for the system clock and GPS
coordinates for the purpose of marking approximate position whenever a VEMCO transmitter is detected
within acoustic range (up to 2 km distance). The VR100 GPS was not intended to provide precise
tracking positions or as a navigation aid designed to assist in planning routes. The VR100 GPS is not to
be used for any applications in which the reliability or accuracy could result in a situation of personal
injury.
For optimal GPS operation ensure that you are using the latest version of VR100 firmware version
(check the website for update).
To check firmware version, select: Config  2 System  6 Version  MCORE
We recommend that you use a WAAS enabled handheld GPS receiver along with the VR100.
The Global Positioning System (GPS) is operated by the U.S. Government, which is solely responsible
for the accuracy and maintenance of the GPS network. The accuracy of position fixes can be affected by
the periodic adjustments to GPS satellites made by the U.S. government and are subject to change in
accordance with the Department of Defence civil GPS user policy and the Federal Radio navigation Plan.
Accuracy can also be affected by poor satellite geometry and obstructions, like buildings and large trees,
and boat canopies.