Vidbildstelevisionssystem med utvidgad skärpa användande ett flertal s ignalöverföringskanaler

摘要

A system for transmitting and receiving signals representing a high-definition television (HDTV) image is disclosed. The signals are sent over two conventional 6 MHz NTSC channels. A first signal, the main signal, is developed by encoding circuitry (112) from HDTV source signals to be compatible with existing NTSC receivers (122) in that it produces a display on those receivers which is not significantly distorted. The main signal includes psycho-physically hidden video information which may be used by an extended definition receiver (128) to produce a widescreen image having a higher level of detail than a conventional video image. A second signal, the auxiliary signal (AUX), is developed at the transmitter by decoding the main signal (140) and subtracting the decoded main signal from the original HDTV source signals. The auxiliary signal, which includes frequency components from 0 Hz to 20 MHz is split into three bands, A (0 Hz-6 MHz), B (6 MHz-12 MHz) and C (12 MHz-18 MHz). Bands B and C are frequency converted to occupy the 0 Hz-6 MHz band and are time division multiplexed on a line by line basis. The combined B and C bands are then time division multiplexed with the A band on a frame by frame basis for still images. For moving images, only the A band is sent. The receiver (136) decodes the main signal, and, using a motion signal sent with the main signal, decodes the auxiliary signal. The decoded main and auxiliary signals are combined to reproduce the HDTV image.