GB893951A - Improvements relating to signal storage apparatus - Google Patents

Abstract

893,951. Radar. ELECTRIC & MUSICAL INDUSTRIES Ltd. July 11, 1958 [April 11, 1957], No. 11871/57. Class 40(7). [Also in Group XL(b)] Simultaneous type colour television signals are derived from sequential type signals by storing successive fields of the latter as a charge pattern on the charge storage electrode of a storage tube 2 coincidently with a biasing stimulus produced by a spot of light which also scans the target storage electrode so that during the second and subsequent field scans the signals derived from the tube consist of the difference between the signals stored during the scan considered and the signals stored during the preceding scanning field together with a constant signal due to the bias stimulus. Such output signals are then combined in adder 3 with the signals being stored during the scan considered the algebraic addition resulting in the production of the signals corresponding to those stored during the preceding scan together with the bias stimulus signal. The latter is removed by a level setting or D.C. stabilizing circuit and the remaining signals, i.e. those stored during the preceding field then occur simultaneously with the signals currently being stored. In the present embodiment the television signals supplied to terminal 1 consist of alternate fields comprising green component video signals and intervening fields comprising red component video signals together with a carrier component amplitude modulated by blue component signals. The green signals are then supplied to terminal 5 either directly from the input at terminal 1 or from the output of adder 3 via switch S1 which "changes-over" at field rate the red and blue signals being likewise simultaneously derived during each field scan and separated out by a L.P. filter 8 and a demodulator 9 on a frequency basis. Other embodiments are described in which the storage arrangement 4 is employed to convert sequential type colour television signals to simultaneous type signals in a system utilizing a colour pick-up tube of the type described in Specification 891,941 (Figs. 2 and 3 not shown) and to produce simultaneous type signals from signals derived from a three field sequential colour television camera (Fig. 4 not shown). The storage apparatus of the invention is stated to be also applicable to radar systems in which it is desired to eliminate components of a signal representing fixed objects. Instead of employing a light stimulus a double beam "reading-writing" tube may be employed one beam being used to "lay-down" the signals and the other to provide the necessary bias stimulus. The scanning of the storage tube(s) and of the connected tubes employed in the embodiments of Figs. 2-4 (not shown) is effected with "spot-wobble" to ensure discharge of the whole area during each field scan period. Specification 657,666 also is referred to.