Service Manual

GSM-205-323
RF overview and RF test function
31st Oct 01
Technical Description: Horizon macro indoor
68P02902W07-B
CONTROLLED INTRODUCTION
Tech. 5–7
Description of
RF test modes
The following description should be read in conjunction with Figure 5-1.
NOTE
The RF test capability described requires software load
GSR5 or later.
The loopback test hardware picks up an attenuated signal by coupled link from
the normal CTU transmit signal.
The signal is mixed down to the receive band for testing the Rx functionality of
the SURF and CTU. Power to the loopback circuitry is automatically turned off
when the radio is in normal operation.
SURF test mode
The loopback signal is injected into the antenna receive path of the SURF by
coupled link. This tests the complete SURF and CTU Rx system path.
Test of CTU Rx circuitry
The loopback signal is injected directly internally into the Rx input of the CTU.
This tests the receive portion of the CTU.
VSWR test mode
The test signal, at Rx frequency, is injected into the antenna port through
coupled link on the SURF. Reflected power is monitored by the receive system
to calculate VSWR. Detection of a high VSWR may indicate the presence of a
cable or antenna fault.