ITT NOKIA 7181 PIP DIGIVISION BLACK - LINE / IFB-681 CHASSIS DIGI BE-2 PIP BLACKPLANIGON 5861 69 49 SOUND PROCESSING UNIT 5827 02 38

ITT NOKIA 7181 PIP DIGIVISION BLACK - LINE / IFB-681 CHASSIS DIGI BE-2 PIP BLACKPLANIGON 5861 69 49 SOUND PROCESSING UNIT Modular Parts. Digital Sound Modul: SEL Stereo Modul DIGI. B

Viewing of Digital Audio - Sound Processing: ADC 2310 (ITT ADC2310) and APU 2470 (ITT APU2470)

Stereo Modul DIGI. B Plug connectors ST 23 and ST 25 constitute the AF signal inputs for the TV I and TV ll signals coming from the RF module. Each of these signals is then passed (via 2 impedance converters and 1 notch filter for suppressing interference frequency components) to Pins 4 and 5 ofthe audio signal converter ADC 2310 E, IC 3101. The stereo pilot carrier is selectively decoupled from sound channel TV ll and fed separately to Pin 8 for recognition of the station operating mode. The digitized output signals are then available as pulse-rate- modulated signals PDM I and PDM ll at Pins 10 and 11. Digital signal processing is then performed completely in APU 2470, the audio processor IC 3201, to which of course all control functions controlled via the IM Bus belong. At IC outputs 22 and 23, the processed signals are outputted as pulse-width- modulated information, so that they can be reconverted into their original analog form by simple integration (RC element). The downstream lC’s TDA 2040 H (3401/3501) supply power amplification for feed to the loudspeakers. A second pair of analog outputs, Pins 19, 20 ofthe APU, followed by an integrated amplifier stage, IC 3301 , TDA 2822 M, serves for connection of earphones or a stereo system via cinch sockets. This output is likewise controllable, and also suitable for the listening to the alternative sound channel in dual-channel sound mode. Pins 21 and 24 at ADC 2310 E are available for coupling a second dual-channel analog sound source. The signals concerned come from the SCART socket (PPT), and in sets with picture-in-picture function are passed via the PIP decoder. In the opposite direction, the ADC 2310 E supplies at Pins 22 and 23 analog output signals to the SCART socket, e.g. as required for recording audio signals. All switch-over functions necessary in this area are executed inside the IC and controlled via the IM Bus. Detection of the station transmission mode (mono, stereo, dual-sound) is performed in the lC’s in exactly the same way as the corresponding switch-over to the operating mode being transmitted. A muting stage in each of the two audio channels (T 3401 and T 3501) provides an audio muting function by short- circuiting the signal input Pin 1 at the power output stage lC’s. This function can be controlled in two different ways: 1. Via ST 33 at the moment when the set is switched on, in order to suppress the switch-on click. 2. From Pin 16 of ADC 2310 E, e.g. for noise suppression, when no TV signal is being received. ln the first case, the L signal, which is passed as a switch-on signal from Pin 5 of the CCU via R 1505 to ST 33 of Stereo Module B, and thus via R 3511 to the base of T 3510, will switch the transistor to on-state and thus connect the muting line to 12 V. Since in this case the two switching transistors T 4301 and T 3501 also become conducting, the signal inputs to the audio output stages are then short-circuited. The second muting branch from Pin 16 of ADC 2310 E is software-controlled, and receives the switch-off information from the CCU via the IM Bus. The stereo module also houses the SCART socket (PPT).