PD178016GC-051_15 Datasheet, PDF (45/96 Pages) Renesas Technology Corp – 8-BIT SINGLE-CHIP MICROCONTROLLER WITH BUILT-IN PRESCALER, PLL FREQUENCY SYNTHESIZER, AND IF COUNTER FOR AUTOMOTIVE FM/MW/LW RADIO APPLICATIONS

µPD178016GC-051
(c) AF reception disable time
This is the period during which the checking of a specific frequency during AF operation is disabled.
While the timer to be referenced is set, the frequency is not checked by the AF operation.
When the tunable frequency is changed (except during AF operation/B.S./EON operation), the AF reception
disable time for all frequencies is cleared.
(d) Setting AF reception disable time
(i) The disable time is set, as shown below, for that frequency at which the AF operation has failed for the
cause of the failure of the operation.
Cause
S • M reading
IF
PI once
PI two times
PI non-coincidence
Disable time
2 minutes
4 minutes
7 minutes
4 minutes
12 minutes
(ii) When the AF operation has been successful, the disable time is set as follows so that the original station
is not restored to the received frequency immediately after the AF operation has been successful.
Disable time
1 minute
(3) AF operation
• Flow of AF operation
<1> All signal meter readings for those frequencies having the same priority are measured.
<2> The measured signal meter readings are sorted starting from the greatest reading.
<3> IF and PI are checked, in this order, starting from the greatest signal meter reading.
When PI coincides, the AF operation is stopped.
<4> If an AF station is not found in <1> through <3>, <1> through <3> are repeated for a lower priority. Where
the priority is 1, however, when a frequency having priority 1 has been received, the signal meter reading,
IF, and PI are successively checked, in this order.
If it is judged that no station is detected, the next frequency is measured.
(a) Single-station AF operation
One station is received and checked by turning on/off mute once, to check the original station.
After the original station has been received for one second, mute is detected (five seconds after if mute is
not detected), and the next station is received and checked.
Example Where two stations have priority 1, three stations have priority 2, and two stations have priority
3 (see Figure 3-3)
<1> A station with priority 1 is received at I, and its signal meter reading, IF, and PI are checked, in this order.
<2> If an RDS station cannot be received in <1> above, the second station having priority 1 is received at
II, and its signal meter reading, IF, and PI are checked, in this order.
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