7.2 Antenna Unit
7-23
7.2.7 Turning operation
1. Automatic tuning operation
The automatic tuning operation includes full search and small search. In these automatic
tuning operations, a start command sent from the SPU board is executed on the RFC
board to control tuning voltage of the MIC. After searching is complete, tracking
operation starts to find the maximum tuning point at all times. Changing tuning voltage
changes local frequency in the MIC. The maximum point of tuning is where the output
frequency of the MIC is converted to the IF frequency of 60 MHz.
A start command, manual setting values, tuning indicator signal (TUNE IND), and MIC
monitor signal (D-MONI signal) presented in a self-test are sent and received using
serial data between the SPU board and RFC board.
Fig. 7.2.17 Schematic Diagram of TUNE Control
The tuning value obtained in full search and small search is saved at U27 (SRAM) of
the RFC board. Searching is performed based on TUNE IND signals.
Fig. 7.2.18 TUNE Control
32V
Time
Time
Tune Volt
Pulse wide
LP LP M3 M2 M1 S2 S1
TUNE Initialize Tracking
Tracking
stop
ST-BY
Tx
Tracking Tracking
Small
search
Small
search
1V
3V
5V
5V
TUNE IND
Changing
Pulse wide
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