By Israel Switzer, Switzer Engineering Services Limited
A system for delivering news and information to cable television subscribers using "digital frame grabbing" is being developed. The use of digital frame grabbing instead of video frame grabbing is rationalized in the light of present technology. Alpha-numeric information in digital form is transmitted repetitively at a very high data bit rate making use of the wide band capability of cable television channels. Information recycle rate is set according to the expected public demand for each particular class of information being handled. A subscriber controlled digital "frame grabber" compares the requested "page number" with the "page numbers" in the data stream in the cable. When the required digital page number is recognized the frame grabber reads the entire "page" into local memory where it is displayed on the subscriber's TV receiver through a local character generator. The cable transmission system acts like a long delay line memory being constantly refreshed by a computer at the "head-end" and being scanned for desired information items by the subscriber's frame grabber. Access times contemplated range from an average one second up to times in the 10-20 second range.