tailieunhanh - Thông tin thiết kế mạch P7

THE TELEVISION RECEIVER In Chapter 6, the coding of video signals in a form suitable for transmission over a telecommunication channel was discussed. In this chapter, the techniques for decoding the signals and their presentation on a cathode ray tube will be examined. The television receiver is almost identical to the AM radio receiver in its use of the superheterodyne principle. There are a few differences in the details of the signal processing due to the greater complexity of the system. Figure shows a block diagram of a typical television receiver | Telecommunication Circuit Design Second Edition. Patrick D. van der Puije Copyright 2002 John Wiley Sons Inc. ISBNs 0-471-41542-1 Hardback 0-471-22153-8 Electronic 7 THE TELEVISION RECEIVER INTRODUCTION In Chapter 6 the coding of video signals in a form suitable for transmission over a telecommunication channel was discussed. In this chapter the techniques for decoding the signals and their presentation on a cathode ray tube will be examined. The television receiver is almost identical to the AM radio receiver in its use of the superheterodyne principle. There are a few differences in the details of the signal processing due to the greater complexity of the system. Figure shows a block diagram of a typical television receiver. The antenna picks up the electromagnetic radiation from the transmitter and feeds it to the radio-frequency amplifier. After amplification and filtering to attenuate other incoming signals from other transmitters the signal goes to the mixer where it is mixed with the output from the local oscillator. As before the local oscillator and the radio-frequency amplifier are tuned to track each other with a constant frequency difference equal to the intermediate frequency. The intermediate frequency for the television receiver is usually MHz. The signal is subjected to further filtering before it proceeds to the video demodulator for the recovery of the baseband information in the signal. The next stage is to separate the composite video signal into its three components namely the video proper the FM sound subcarrier and its sidebands and the vertical and horizontal control pulses. The video signal is amplified to the level required to drive the picture tube by the video amplifier and the vertical and horizontal control pulses are suitably conditioned and used in the deflection systems of the receiver to synchronize it to the transmitter - a condition that must be met for proper reproduction of the images sent. The FM signal is .