Greetings, I am starting out with the GPS toolkit and RFSG combination via 5441 (AWG) + 5610 (RF Upconverter) combination.
I am running Labview 8.6.1, with Modulation and GPS toolkits installed.
I have two issues:
1. When I run the 'niGPS Streaming From File(5671).vi', I periodically get this error message: DAQmx Error -200617: Output generation was aborted by the reverse power protection circuitry of the device... When I let the device sit for an hour or two, the error message does not appear anymore when attempting to stream from a waveform file. Has anyone seen this error? What would cause this message? Could it be the SMA connections are a bit loose on the Upconverter output connector and upconverter is detecting this?
2. Once the first issue is bypassed, ususally by waiting for an hour or so to use the equipment, no GPS module can lock on to the signal. Per the app note at http://zone.ni.com/devzone/cda/tut/p/id/7189, under the heading "Setting up a GPS Measurement System", I have connected a DC block and 60 dB of attenuators on the output of the Upconverter.
When I choose a reference output amplitude value in the range from -60 to +0 dBm on the streaming from File vi, I see that in my NMEA 0183 GPGSV message that satellites are being detected by the DUT. The SNRs are on the order of 10 to 15 dBm for each satellite in the waveform, which should be enough based on outdoor experience reading GSV messages.
However, after hours of waiting, I get no 3d position fix despite the fact that the SNRs indicate that I should be able to form a position.
Why is the GPS simulator not working? I am using Almanac and Ephemeris files to create the waveform file from the links in the app note under the heading "Creating Simulated GPS Signals".
Is it necessary to use current almanac/ephemeris files? I am using almanac/ephemeris files from the same date, per the app note. Has anyone else found the the GPS toolkit to be this sensitive to configuration parameters, or has it been "toaster-like", and I am very unlucky?
