TDA7705 Weak signal processing
Doc ID 15938 Rev 9 33/42
5 Weak signal processing
All the parameters in this section refer to the programmability of the DSP part of the device.
The typical values are those set by default parameters (start-up without parametric change
from main µP); the max and the min values refer to the programmability range. The values
are referred to the typical application (Figure 16: Example of FM tuned (narrow-band)
application / SPI control). Wherever the possible values are a discrete set, all the possible
programmable values are displayed.
5.1 FM IF-processing
5.1.1 Dynamic channel selection filter (DISS)
5.1.2 Soft mute
Table 26. Dynamic channel selection filter (DISS)
(discrete set)
Symbol Parameter Test condition Min Typ Max Units
DISS BW
IF filter #6
response: - 3dB
- ±150 - kHz
IF filter #5 - ±110 - kHz
IF filter #4 - ±80 - kHz
IF filter #3 - ±60 - kHz
IF filter #2 - ±45 - kHz
IF filter #1 - ±35 - kHz
IF filter #0 - ±25 - kHz
Table 27. Soft mute
(continuous set)
Symbol Parameter Test condition Min Typ Max Units
SMsp Start point vs. field strength
audio atten = 1 dB
read “FM_softmute”
no adjacent channel present
0 6 20 dBµV
SMep End point vs. field strength
audio atten = SMd + 1 dB
read “FM_softmute”
no adjacent channel present
-6 -6 10 dBµV
SMd Depth - -30 -15 0 dB
SMtauatt
Field strength LPF cut-off
frequency for soft mute
activation
- 0.1 100 4000 Hz
SMtaurel
Field strength LPF cut-off
frequency for soft mute
release
- 0.1 1 4000 Hz
