Abstract: Television receivers are increasingly making use of digital signal processing. Present-day television receivers use a line-coupled clock system in this case, since this produces an orthogonal pixel array for signal processing on the picture screen. The disadvantage of such a clock grid resides in its problematical generation, in particular when video recorders are used as signal source. According to the invention, video signals are digitized and processed by means of a free-wheeling system clock made from a quartz oscillator. In order not to have to use large buffer memories, the vertical deflection is synchronized with the input signal, but the number of lines per field or frame is varied.

Abstract: For compatible transmission of a television picture having an aspect ratio of 16:9 within a 4:3 system, transmission is effected in the letterbox format in accordance with the PALplus system specification. The receiver reconstructs the original picture with the aid of vertical filters and is able, furthermore, to suppress crosstalk interference from the luminance signals in the chrominance signals. To further improve the picture quality, the picture is displayed at a frame frequency of 100 Hz. For this purpose, the picture supplied at 50 Hz with line interlacing must be converted to a frame frequency of 100 Hz. Known concepts for PALplus decoding and 100 Hz conversion carry out these processes separately and in doing so require a great deal of memory space.

Abstract: For many signal processing arrangements in TV receivers it is necessary to know the type of signal source. A plurality of parameters must be set depending on whether a standard-conforming source and hence a standard signal or a non-standard source (for example VCR) is involved. The circuit according to the invention is capable of making a statement in a TV receiver as to whether or not a source corresponding to the TV standard is present. For this purpose, the locking of the color subcarrier with the horizontal frequency is investigated and two different criteria (FSCFH, CCC) are utilized for the decision. The optimized setting of parameters in the receiver is possible with the aid of the decision made. Furthermore, the circuit provides, in the event of a standard signal, a highly stable sampling clock (fLL1) of the kind necessary, for example, for ColorPlus processing within the PALplus system.