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CP-520/520A/520F Service Manual
DTV R&D Europe
45
intercarrier and an external second SIF(2NDSIFEXT), e.g. an intercarrier coming from a PIP
frontend. In other applications a 10.7MHz radio IF or satellite FM may be connected to this input.
The selected SSIF passes some anti alias filtering, is amplified in an AGC amplifier (SSIF AGC)
and is then converted from analogue to digital (SSIF ADC).
The audio signal out of the AM demodulator is connected to the analogue crossbar at the video
processor. All other inputs to this multiplexer/audio switch come from external, either from a PIP
frontend or SCART/CINCH(AUDINx) or the DAC output signals from the digital controller. The
audio AD converters are digitising the audio signals foreseen for further digital processing. One
stereo output (AUDOUTS) is available for connections to SCART/CINCH sockets.
The sound part on the digital controller consists of the demodulator/decoder(DEMDEC), a digital
input crossbar, the digital audio processing for the loudspeaker and DAC channels, the I2S
processing and interfacing, a digital output crossbar as well as the DA conversion.
An auxiliary audio control (volume control, AUX audio contr.) is available on the video processor.
Here it is applied to the headphone channel.
The part of the concept located in the digital controller will be described in the next chapters.
5.4.2 Functional Overview Of the digital controller sound part
The digital controller sound part consists of the SSIFADC, audio ADCs, DEMDEC HW, the sound
DSP core, audio DACs and I2S interface hardware as shown in fig below. The DEMDEC part of
the Sound DSP is used for the decoder and partly demodulator tasks. The AUDIO part provides
the sound features, from the level adjust unit up to the output crossbar. Audio DACs and I2S
hardware are converting the processed signals to analogue or digital audio.
The SSIF signal is applied to the SSIF ADC for conversion and is then fed to the DEMDEC
hardware processing mainly for demodulation but also some decoding tasks. Remaining