Factory test is a GLL operational mode for production hardware testing.
The factory test is capable of detecting:
There are two different factory test modes:
To conduct the factory tracking test the signal simulator must be configured to generate the satellite signal at the center frequency. There are two configurations, one is GPS only and other is GNSS (GPS+GLONASS). A GLCT entry, like the example entry below, creates the Factory Test Request. The user should edit the PRN and FCN parameters appropriately. For reliable results, the signal is expected to initially be in the range of -125dBm to -142dBm with the frequency offset in the range of -2 ppm to +2 ppm. Once the signal is found in the specified range, the power level can be reduced to perform an tracking test at lower signal levels.
GPS
<job id="Factory_GPS_Track_Test"> <task id="test" repeat="1"> <startup IgnoreOsc="true" IgnoreRomAlm="true" IgnoreRamAlm="true" IgnorePosition="true" IgnoreNav="true" IgnoreTime="true" /> <req_ftest Prn="1" FactoryTestItems="GL_FACT_TEST_WER" FactoryTestMode="GL_FACT_TEST_CONT" AveragingIntervalSec="10" DurationSec="120" /> </task> </job>
GNSS (GPS+GLONASS)
Here the "FCN" number corresponds to a particular GLONASS satellite frequency, which can be found in the table below.
The GPS signal at the specified PRN must be present.
<job id="Factory_GNSS_Track_Test"> <task id="test" repeat="1"> <startup IgnoreOsc="true" IgnoreRomAlm="true" IgnoreRamAlm="true" IgnorePosition="true" IgnoreNav="true" IgnoreTime="true" /> <req_ftest Prn="1" Fcn="0" FactoryTestItems="GL_FACT_TEST_WER" FactoryTestMode="GL_FACT_TEST_CONT" AveragingIntervalSec="10" DurationSec="120" /> </task> </job>
To conduct the factory CW test, the signal simulator must be configured to generate the signal for one GPS satellite or one GLONASS satellite respectively: For GPS the signal should be at +200 kHz offset relative to center frequency i.e., L1+200 kHz = 1575.62 MHz. For GLONASS the signal should be at FCN0(= 1602 MHz) frequency.
An example factory CW test configuration entry for the GLCT is shown below.
GPS
<job id="Factory_GPS_CW_Test"> <task id="test" repeat="1"> <startup IgnoreOsc="true" IgnoreRomAlm="true" IgnoreRamAlm="true" IgnorePosition="true" IgnoreNav="true" IgnoreTime="true" /> <req_ftest FactoryTestItems="GL_FACT_TEST_CW" FactoryTestMode="GL_FACT_TEST_ONCE" AveragingIntervalSec="10" DurationSec="60" /> </task> </job>
GLONASS
Here the "FCN" number corresponds to a particular GLONASS satellite frequency, which is FCN=0 for CW test.
<job id="Factory_GLONASS_CW_Test"> <task id="test" repeat="1"> <startup IgnoreOsc="true" IgnoreRomAlm="true" IgnoreRamAlm="true" IgnorePosition="true" IgnoreNav="true" IgnoreTime="true" /> <req_ftest Fcn="0" FactoryTestItems="GL_FACT_TEST_CW" FactoryTestMode="GL_FACT_TEST_ONCE" AveragingIntervalSec="10" DurationSec="60" /> </task> </job>
The req_ftest element should have the following attributes specified:
FCN Frequency(MHz) -7 1598.0625 -6 1598.625 -5 1599.1875 -4 1599.75 -3 1600.3125 -2 1600.875 -1 1601.4375 0 1602.0 1 1602.5625 2 1603.125 3 1603.6875 4 1604.25 5 1604.8125 6 1605.375
If you don't use the GLCT your application must create the GlRequest object using the GlRequest::MakeFactTestReq() method.
The output of the factory test is provided through the $PGLOR,3,FTS - Factory Test Status NMEA message.