Measurements to test the GPS receiver, antenna, and cabling

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Description: Customers have experienced sync issues and have asked how to test the GPS cable. Below is the process and measurements that are expected when troubleshooting the GPS sync problems.

How to Troubleshoot: From the GPS connector at the CMM use a volt meter to measure how many volts are coming from the GPS receiver. The expected measurement is 5 volts. Next, to measure the current between the CMM and the antenna make sure the antenna and GPS are using a common ground. Place a meter in series to test the center conducter of the cabling to the antenna. Here you should get a current measurement of about 26mA. If you are measuring more than 26mA then you will possibly have a short. If you measure a lot less than 26mA then you have cable loss or an open.

Work Around: First step would be to replace the ends of the cable and take the measurements again. If this does not change the values then the cable will need to be replaced.