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Step Global |
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Brand: Racelogic
An important factor of GPS testing is that of receiver sensitivity. The main areas of test are acquisition sensitivity and tracking sensitivity. Typically, the RF power level received by an antenna on the ground will be between -125 dBm and -150 dBm depending on environmental factors.
To generate very low RF power levels in this range, it is required to use external passive attenuators to reduce the LabSat output. In this way, the signal level is reduced to the required range with minimal added noise. Actual values of attenuation should be determined by the user to suit the equipment under test but as a guide, two in-line 20 dB attenuators (40 dB total) will give an RF power range of around -113 to -144 dBm.
Although a user-recorded RF signal can be used for testing in this way, the recommended method is to use a computer-generated simulation file created using the SatGen software. This is because the SatGen created file will contain a "pure" GPS signal with constant signal to noise ratio.
A user-recorded scenario will contain additional noise that was present during recording and will also have constantly changing signal to noise levels which make comparison difficult.
