ATR4258 Datasheet, PDF (18/38 Pages) ATMEL Corporation – AM/FM RECEIVER IC

Adjacent Channel
Sensor
The adjacent channel sensor is active in FM mode only and measures the field strength
outside the reception band.
Figure 8. Adjacent Channel Sensor
IF
SMeter
Pin 9 (Meter)
+
Pin 10 (ADJAC)
30 µA
MPINT and ADJAC Reset Bit 6 allows a resets of the multipath sensor and the adjacent channel sensor by con-
necting pin 10 and pin 40 internally to ground and so the external capacitors can be
discharged very quickly.
Multipath Sensor
Table 30. Multipath and Adjacent Channel Reset
MPINT and Adjacent Channel (Pin 10 and Pin 40)
Normal mode
Connection to ground
Bit 6
0
1
The multipath sensor is active in FM mode only and measures the disturbance due to
multipath reception. The multipath sensor detects drops in the field strength after the
integrated band filter by calculating the difference between an averaged maximum field
strength and the current field strength. The maximum depth of these drops is repre-
sented by the voltage of the peak detector at pin 40 (MULTIP). The level of this voltage
represents the degree of disturbance in the received signal.
Figure 9. Multipath Sensor
+
Pin 40
4k
18 ATR4258
4838A–AUDR–10/04