Patent GB-1279306-A (GB)
Title: Random access information retrieval system
IPC: G09B5/12
Filed: 1969-09-05
Abstract: 1279306 Computer-controlled audio-visual teaching systems AMPEX CORP 5 Sept 1969 [9 Sept 1968] 43971/69 Headings G4A G5G and G5R A selective retrieval information storage system has a random access store and is such that a plurality of users acting independently of each other can make simultaneous use of the system. The store contains recorded information such as lessons or teaching programs and when any of a plurality of students requires to use any of the recorded lessons or programs it is transmitted to an information receiving unit at a speed higher than the normal play-back speed, e.g. a 30-minute lesson would be transmitted in 15 seconds. Each student receives such lessons or programs at a station with facilities for playback at normal speed of the information received at the high speed. The system is computercontrolled and the recorded information may be audio alone or synchronized audio-video. In Fig. 1, a key-board 27 at each of a plurality of student carrels 26 is operable to introduce commands for particular items of information, such commands being directed to the information store, viz. a master memory bank 12, by way of the units 28, 18, 20 as indicated by the singleline-stemmed arrows interconnecting these units. The consequence is retrieval of that information in the manner indicated by the double-linestemmed arrows from the memory bank 12 by way of a switching unit 16 to whichever of a plurality of student buffers 14 corresponds to the commanding carrel. From here it is relayed, at normal speed, by way of a teacher's console 30 and switching unit 34 to the commanding student carrel for reproduction of audio information on head-phones 54 and of video information, if provided, on a screen 56. Figs. 2 and 3 (not shown) depict the equipment at one such carrel, which includes a microphone by which the student can either speak on to the tape on which his received lesson is recorded or can communicate with a teacher at the console 30. The console can include means for automatically logging the use made of the system by each student. The facility is also provided for information to be requested at a keyboard 27<SP>1</SP> in a unit 59 which can be loaded with a tape cassette on to which the requested information will be recorded at high speed. The cassette can then be removed for use at normal play-back speed on any suitable tape recorder. Telephoned requests for information can also be handled either automatically by way of the units 40, 38, 28 and thence as above described or by way of a verbal request to the console, which has its own keyboard for requesting information. Figs. 4 and 5 (not shown) depict modifications of the Fig. 1 system, but with the difference that whereas in Fig. 1 the audio and video sources are merely linked to a common computer, the Fig. 4 and 5 systems employ master memory banks in which the video information is stored along with the audio, either as a direct recording or as code signals which are conveyed to a student buffer along with related audio information, the code signals defining an address from which the relevant video information will be automatically relayed to the student carrel along with the audio information. Play-back of combined audio-video recordings can be effected by use of slow-scan television methods in the following manner. A set of still pictures, each illustrating an item of audio information, is video-recorded at slow scan rate and recorded on tape along with the audio information, the slow scan ensuring that the video recording will have much the same bandwidth as the audio. Audio and video signals may either be recorded on adjacent tracks or as respectively AM and FM signals on a single track. When the audio information is relayed at high speed, e.g. to a student buffer 14, the video information is also relayed. However, since subsequent playback of the audio at normal speed will also produce a slow-scan reproduction of the video, an intermediate step is necessary, employing a converter 62, Fig. 4 (not shown) whereby the received slow-scan video recording is converted into a form suitable for reproduction on a television screen at normal sweep speed. The converter accumulates incoming video information until a complete frame has been received and then re-records it in such manner that the frame will be played back several times in succession at the normal scan rate in the time in which one slow-scan frame could be played back.