Testing GPS Antennas

[CDNTech]

I did a search and didn't find anything that appeared directly applicable. I am servicing mobile location reporting devices, a component of which is a power injection board feeding active antennas. This is nothing unusual, however I want or need to develop a reliable way to compare antennas and determine whether a particular antenna installation has problems, or if the problem arises elsewhere.

I read another thread discussing the inability of using a spectrum analyzer in this pursuit due to the GPS signal being so far below the noise. For individual dis-connectable components, I could use a VNA to measure loss/gain, however essentially there are only two components (ignoring interconnects): the antenna with built-in LNA and coax and the power injection circuit.

Can anyone provide a relatively inexpensive system for doing these measurements to create a pass/fail system to rule out the antenna system as a problem?

I was about to pull the trigger on a relatively inexpensive spectrum analyser, which *could* indicate if there were strong signals near the GPS frequency (cellular in particular) interfering, but that apparently (for the purposes of this discussion) would be its' only use.

Thanks!

 

[ernie]

Wouldn't it be possible to use a GPS receiver that outputs NMEA sentences and a simple program like VisualGPS to display signal levels? If you want pass/fail, you could write a simple BASIC program to read the applicable NMEA sentences, parse them and just print pass or fail after a few minutes of collecting signal strength data. Or am I totally misunderstanding your needs?