User's Manual

SECTION 4: FACTORY TEST PROCEDURE
M64450G25-FCCRpt.doc Page 39
The next plot is the same as before but now the scope is in the peak detect acquisition mode. After the
mobile radio detects a step response in the RSSI (caused by a down-link transmission), the mobile radio's
microcontroller waits an amount of time equal to the programmed value of the "carrier detect delay time"
then instructs the modem to look for frame sync. When the microcontroller instructs the modem to look for
frame sync, it asserts the modem's CS line (active low). In this plot, the modem's CS line can be seen to
transition low approximately 3 milliseconds after the base station's transmitter has come up to full power.
The recovered modulation should be centered at approximately 2.5 VDC and should have the amplitude
of approximately 800 mV peal-to-peak as indicated in the plot above.