User's Manual

SECTION 4: FACTORY TEST PROCEDURE
M64700G25-FCCRpt.doc Page 34
The plot shown in the figure below 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 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 an amplitude
of approximately 800 mV peal-to-peak as indicated in the plot above.