Fernsehempfaenger,申请号DE19671512437-传众专利搜索

Fernsehempfaenger

申请公布号：DE1512437(A1)

申请号：DE19671512437

申请日期：1967.01.12

申请公布日期：1969.03.27

申请人：

SINCLAIR RADIONICS LTD.

发明人：MARLES SINCLAIR,CLIVE

分类号：H03D1/22;H04N5/44;H04N5/455

主分类号：H03D1/22

摘要：1,129,241. Diplex radio signalling; transistor radio receiving circuits. SINCLAIR RADIONICS Ltd., and C. M. SINCLAIR. 14 Jan., 1966, No. 1947/66. Headings H3T and H4L. In a synchronous detector for a television receiver an oscillator and mixer circuit receiving a composite television signal input is adapted to be injection-locked to the vision carrier frequency, or to an integral multiple thereof, and is connected to a video amplifier. As described, signals received on an aerial 1 are applied, after amplification by an R.F. amplifier comprising a common-base connected transistor 22, to the emitter of a common-base connected transistor 24. A variable inductor 25 connected to the collector of the transistor 24 is ganged with the input tuning coil 18 of the R.F. amplifier and forms part of an oscillator circuit comprising also the collector to base capacitance of the transistor 24, a capacitor 26 shunting the emitter and collector of the transistor 24, and decoupling capacitors 30, 31. This oscillator locks in with the video carrier, and causes the transistor 24 to act as a synchronous detector, so that the output on a lead 34 includes detected video signals and also signals at the intercarrier frequency, that is, the difference between the frequencies of the audio and video carriers, which are modulated by the audio signals. The video signals are amplified by transistors 35, 36, 37, output being given on a lead 46. A tuned transformer 38 selects the intercarrier signal which is amplified at 41 and demodulated at 44. Audio signals are obtained on a lead 45. The combined mixer and oscillator, comprising the transistor 24, may be replaced by separate mixer and oscillator stages, and the R.F. amplifier, comprising the transistor 22, may be followed by a frequency conversion stage.