User Manual

SECTION 2: FACTORY TEST PROCEDURE
IP4HPVGPS-MRFCCRpt.doc Page 16
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Uplink Hardware Timing Verification
Figure 2-1 below displays an oscilloscope plot of an uplink data message from the mobile to the base
station. Channel 1 is connected to the base station's RSSI (XXX-12), channel 2 is connected to the base
station's recovered modulation, and channel 3 is connected to the base station's modem chip select line.
The scopes acquisition mode is high-resolution.
Figure 2-1: Oscilloscope Plot of an Uplink Data Message
As seen in the above plot, the mobile radio's transmit carrier has ramped up to full power (channel 1) in
just a few milliseconds. The recovered modulation (channel 2) is stable by this time. There follows a few
milliseconds of quiet time followed by 12 milliseconds of symbol sync time.
The recovered modulation from a mobile radio should look identical to this plot. The recovered
modulation signal should be approximately 1.0 Volts peak-to-peak and should be centered at
approximately 2.5 VDC as is indicated in the figure above.