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3.25 GPS Receiver Test
The Conducted signal testing described below can be performed to analyze or root cause an issue
along the GPS RF subsystem, using a CW signal. The following tests are implemented in Factory
Test Mode (BERBUG Mode).
Test Setup
1. Set up the CW generator as follows: Frequency = 1575.42 MHz, Amplitude level = -80
dBm. Amplitude levels above -76 dBm will compress the Janus IC.
2. Remove the antenna and replace it with a 50 OHM coax. Power up the Unit Under Test
(UUT), and connect the CW generator to the UUT.
3. Using Hyper Terminal, GPS is turned on as follows:
BERBUG > gps on
4. Set the Spectrum Analyzer to Center Frequency = 1575.42 MHz, Span = 1 MHz,
Amplitude Reference Level = -50 dBm.
5. Use a High Impedance Probe to follow the signal flow along the GPS RF subsystem, block
by block.
Block Level Testing of Critical Stages
Below is a list of Critical Stages/Blocks, and their respective RF test points:
1. GPS (M500B10): GPS antenna port.
2. Sledgehammer IC (U600B10): IF frequency test pad.
DC Power Supply
When testing, it is advisable to utilize an external DC Power supply set at 4 Volts and a current
level of 2A. In BERBUG Mode, the UUT is expected to draw 60 mA to 65 mA at power up. By
entering "gps on" the UUT should draw 97 mA to 102 mA
6880401P59-O
TROUBLESHOOTING: GPS Receiver Test
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