| 摘要 |
A system for converting a broad-band picture signal into a narrow-band signal or converting a narrow-band picture signal into a broad-band signal comprising a first memory means which has a capacity of storing a picture signal corresponding to one frame and can record and reproduce a broad-band picture signal at the same speed as the transmitted speed, and a second memory means which has a capacity of storing a picture signal corresponding to one scanning line and is such that writing speed and reading speed can be freely varied. In broad-to-narrow conversion, a broad-band picture signal corresponding to one frame is stored in the first memory means and is read out repeatedly from the first memory means at a speed equal to the speed with which a picture signal is commonly transmitted, and individual line signals appearing from the first memory means are successively written in the second memory means at a suitable time interval and are read out from the second memory means at a low speed corresponding to the desired frequency band. In narrow-to-broad conversion, individual line signals of a broad-to-narrow converted picture signal are successively written in the second memory means at a low speed and are read out therefrom at a high speed to be written in the first memory means, and after the signal corresponding to one frame is written in the first memory means according to the order of the scanning lines, this signal is read out from the first memory means to provide a broad-band picture signal. A plurality of second memory means may be provided so as to improve the efficiency in respect of time of transfer of the signal from the first to the second memory means or from the second to the first memory means and to reduce the period of time occupied by the broad-to-narrow converted frame signal.
|
