Globalstar Product Management – Technical Support

Mobile Position Determination in Globalstar

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Globalstar must determine the location of a phone/modem in order to provide optimum service.  The location is determined using the method described below.

Mobile Position Determination (MPD):

The Globalstar System calculates the location of a phone (or modem) using a technique called Mobile Position Determination (MPD).  The MPD algorithm combines time, angle and distance information from the satellite signals to determine geographic position in latitude and longitude (DMS).  There are many variables that affect the accuracy of MPD.  Some of these are the number of satellites serving the call, the distance between the user and the satellites, and the positions of the satellites in the sky.

MPD Accuracy:

It should be understood that MPD does not posses the inherent accuracy of the GPS (Global Positioning System). Most modern GPS receivers track 12 satellites at one time and derive very accurate position location. Since the Globalstar user terminal does not have GPS capability and is capable of tracking a maximum of three (3) Globalstar satellites at any given time, the accuracy of MPD is considerably lower than GPS accuracy.

How to Display Location:

Position location data is provided on all Globalstar handheld phones, car kits, fixed phones and modems.

.     Handheld Phones  — GSP-1700 and GSP-1600, whether stand-alone or in a carkit:

  1. If you have a Globalstar GSP-1700 or GSP-1600 phone, simply press “MENU” “4”, “3”.  If the position information is not yet available, press “UPDATE”.  The screen will then provide the latitude and longitude.
  2. Please note that you must have a call in process for this location information to be updated.
  3. To get up-to-the-moment position information, you must press “UPDATE”.  You can press “UPDATE” multiple times during a call.
  4. Pressing the “DOWN ARROW” or “#” key will display the estimated MPD calculation accuracy, and also the time and date that the location information was obtained.

.     Data Interface on all Globalstar Phones and Modems:

If you are using the data interface to your phone or modem, you can obtain the Globalstar MPD location coordinates and location accuracy estimate by issuing the AT command, AT$QCPLS.

Written by Joseph Crowley

June 8, 2017 at 12:08 am

Posted in Position Location

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