| 摘要 |
468,505. Television. RADIOAKT.- GES. D. S. LOEWE. Jan. 6, 1936, No. 439. Convention date, Jan. 9, 1935. [Class 40 (iii)] Synchronizing impulses are separated by an amplitude filter which is rendered effective just before the arrival of a synchronizing impulse. The synchronizing impulses are produced by a suitable edging to the picture and are of the form shown in Fig. 2b at A. At the receiver, the received signal is de-modulated by a grid leak type detector 11 connected directly to an amplitude filter 14. The grid 23 is biassed from a source 28 and also from a deflecting electrode 25a of the cathode-ray tube. The filter 14 is thus arranged to be biassed to cut-off except when the deflecting potential applied to the electrode 25a reaches its maximum, i.e. at the end of each line. The synchronizing impulse then applied to the filter renders the cathode 15 negative with respect to the anode 19 (corresponding with the sudden drop tz in the synchronizing pulse) so that an impulse passes through the filter 14 to trip the deflecting oscillator. A grid 23<1> is similarly biassed to control the framing oscillation generator. |
