Technology of Q 2500 colour TV set

Technology of Q 2500 colour TV set4 Signal boardMounted on the signal board, which is linkedto the basic board via connectors, are all thenecessary building blocks for device control,interface switching, video, audio and videotextprocessing.These are:- The device control with computer circuit,operating software and the EAROM for thestoring of system data and customer specificcalibration values.- Production of system cycle frequency necessaryfor a digital design.- The digital IC’s necessary for picture signalprocessing.- The video/deflection processor for the productionand synchronization of controlpulses.- Digital audio processing for analogue transferredinformation and NICAM decoding.- The teletext decoder, integrated into theSDA 6000, with page memory, in which upto 3000 text pages, according to design,can be saved and which also generates theOSD for the user control.- The signal and interface selection by correspondingIC’s controllable via the I²C bus.- Optional IC’s for video processing, picturein picture.4.1 Device controlFull device control is implemented by a Siemens16 bit processor (SDA 6000) togetherwith Loewe operating software. The teletextfunction is also integrated into the SDA 6000.A standalone teletext processor is thereforenot necessary.All processes in the digital signal preparation,in the tuners and interface selection arechecked and controlled via a microcomputerintegrated into the SDA 6000. The processoris also known as the CCU (Central ControlUnit).It also supports the operating, tuning andstorage system on the frequency synthesisprinciple. Without the DVB module there are220 programme storage locations, and withthe DVB board there are 1470. The programmelocations are available for TV andalso for radio operation. The total number ofstored programs must not exceed 220 (1470).For the AV inputs six additional places arereserved.Operating software is held in an externalEPROM. For the storage of c.r.t. and systemspecific data there is an EAROM for devicecontrol. The latter also contains programmelocation information.All three modules, CCU, EPROM and EAROMare mounted on the signal board.The remote maintenance sensor permits controlof possible device functions. The chassistuning is also carried out by remote maintenance.For this, the sensor IC generates a serial dataword for each command that is transferred tothe receiver with a delay. This signal is demodulatedby the IR receiver and prepared insuch a way that it can be sent directly to theCCU as an RSIG signal.The CCU detects the local operating commandson a line by the different voltage levels.Document Q 2500 60 © Loewe ProCollege