Technology of Q 2500 colour TV set

Technology of Q 2500 colour TV set5.2.6 Audio base band processorIn the DFP there is a pre-amplifier for all threedigital VF signal pairs; Nicam A/B, FM 1/2 andScart L/R. The adjustment of the pre-amplifierfor each VF input pair is independent and isdetermined by the software. This means thatfor further processing nearly the same digitalVF level is available.For the FM 1/2 and Nicam A/B signal pairs thepre-amplifier is followed by the necessary deemphasis.The FM 1/2 VF signal pair is fedonward to the FM matrix. For an FM stereotransmission the stereo L and R signals arere-constituted from the L+R/2 signal of FM 1and the R signal of FM 2 in the FM matrix.The FM matrix is controlled by SDA 6000 viathe I²C bus according to the selected operatingmode - stereo or mono. In the followingchannel selection, after the selected operatingmode, the selected VF signal is switched tothe VF output branches in the MSP, which arecontrolled independently of one another, forloudspeaker, headphones and interface selection.MonoAudio Base Processor (DFP)Loudspeaker branchScart / LScart / RFM 1FM 2DeemphasisMatrixChannel selectionMatrixMatrixBassTrebleLoudnessbase widthHeadphones branchVolumeBalance2xD/ABeeper2xD/ALRLRNicam / ANicam / BDeemphasisMatrixInterface out.2xD/ALR5.2.7 Loudspeaker branchAfter channel selection the two VF channelsare led to the digital filter and control stages,which are all controlled from the CCU via theI²C bus. As the processing for both channelsis identical, the following description will dealwith one channel only.louder than deeper or higher frequencies. Thefilter coefficient necessary for the reduction isdetermined and is applied in varying strengthsto the signal, depending on the volume.5.2.8 LoudnessThe signal comes from the matrix and is fedinitially to a filter with which an ‘as heard’loudspeaker control (Loudness) is implemented.Depending on the loudspeaker settingfrequencies around 1 kHz are reduced, asfor same sound pressure the human earsenses these frequencies as being a lot5.2.9 Sound settingThe sound control stage consists of two separatefilters for the height and bass settings.The control range for the two filters is +12 dB.Document Q 2500 115 © Loewe ProCollege