ATR4255 datasheet(14/32 Pages) ATMEL

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ATR4255

4837A–AUDR–10/04

Deviation Sensor

The deviation sensor is active in AM and FM/WB mode and measures the modulation of

the signal. It is implemented as a peak detector of the lowpass-filtered MPX signal (see

Figure 7). The output voltage at pin 31 is proportional to the frequency deviation in

FM/WB or the modulation depth in AM respectively.

Figure 7. Deviation Sensor

Table 23. Search Stop Detector Measurement Time

Time Window for Stop Signal

Bit 78

Bit 77

Bit 76

Bit 75

Bit 74

Bit 73

× 3.1969 ms

.....

× 3.1969 ms

Table 24. Search Stop Window

Search Stop Window

Bit 87

Bit 86

Bit 85

±0.5 kHz

±1.1 kHz

±2.3 kHz

±4.8 kHz

±10 kHz

±20 kHz

±40 kHz

±80 kHz

Table 25. Signals Available at Digital Output Pin 21

Bit 88

Bit 92

INT (Pin 21)

00 (AM)

1 (FM/WB)

NOT MPINT

10 (AM)

NOT STOP

1 (FM/WB)

NOT (STOP AND NOT MPINT)

MPX

Pin 31

25k

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