TDA7406 Datasheet, PDF (42/64 Pages) STMicroelectronics – Car radio signal processor

Functional description of the multipath-detector
TDA7406
10 Functional description of the multipath-detector
Using the Multipath-Detector the audible effects of a multipath condition can be minimized.
A multipath-condition is detected by rectifying the spectrum around 19kHz in the
fieldstrength signal. An external capacitor is used to define the attack- and decay-times for
the Stereoblend (see block diagram, fig. 32). Due to the very small charge currents this
capacitor should be a low leakage current type (e.g ceramic). Using this configuration an
adaptation to the user's requirement is possible without effecting the “normal” fieldstrength
input (LEVEL) for the stereodecoder. This application is given in fig. 28. Another (internal)
time constant is used to control the Highcut through the multipath detector
Selecting the “internal influence” in the configuration byte the Stereo-Blend and/or the
Highcut is automatically invoked during a multipath condition according to the voltage
appearing at the MP_OUT-pin.
Figure 30. Block diagram of the Multipath-Detector
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