Available online
Description
The programme looks at digital measurements in the areas of digital weighing machines, sampling analysis systems, and testing the acoustical properties of loudspeakers.
The programme looks at digital measurements in the areas of digital weighing machines, sampling analysis systems, and testing the acoustical properties of loudspeakers.
| Module code and title: | T283, Introductory electronics |
|---|---|
| Item code: | T283; 09 |
| First transmission date: | 06-09-1980 |
| Published: | 1980 |
| Rights Statement: | |
| Restrictions on use: | |
| Duration: | 00:23:08 |
| + Show more... | |
| Producer: | Ted Smith |
| Contributors: | Raymond Cooke; N. W. Heap; Glyn Martin |
| Publisher: | BBC Open University |
| Keyword(s): | Acoustics; KEF Electronics Maidstone; Loudspeakers; Measurement |
| Footage description: | Nick Heap with a set of butchers scales introduces the programme. Nick Heap examines the scales in detail. He shows that by using the conversion table on the scales, a digital price can be determined from an analogue weight reading. Heap briefly explains the difference between accuracy and resolution in this type of system. Next, with the aid of a balance type set of scales, Nick Heap demonstrates another analogue to digital conversion system. He points out the smallest incremental change which can be made with this balance and calls it the quantisation interval. This is a fundamental error which is introduced when converting analogue to digital signals. Nick Heap then uses a schematic diagram to discuss a possible design for a set of electronic digital scales. Using a digital storage oscilloscope, Nick Heap goes on to examine some problems in sampling sinusoidal waveforms. Then with the aid of a drawing board and mirror, he explains why the phenomenon of aliassing occurs and how this introduces sampling errors. Glyn Martin at KEF Electronics points to and explains briefly a stereo loudspeaker system. He stresses the need for the speakers on such a system to have matched frequency responses. Raymond Cooke, KEF Managing Director, explains why his company uses impulse testing to check the acoustical characteristics of the system. Nick Heap looks at the computer testing equipment at KEF Electronics. With it he demonstrates the basic principles of impulse testing. Raymond Cooke explains why the economics of impulse testing are so attractive for his company. Nick Heap demonstrates an impulse test on an actual speaker. He points out that by averaging many impulses together, noise can be virtually eliminated. Film shots of loudspeaker systems on the assembly line undergoing impulse testing. Commentary by Glen Martin explains what is happening. Raymond Cooke briefly explains how his company also uses computers for general quality control of speaker systems. Nick Heap ends the programme with a brief discussion on the use of computer graphics in speaker cabinet design. Shots of a computer generated animated diagram of a speaker cabinet. |
| Master spool number: | OU 3386 |
| Production number: | FOUT059W |
| Videofinder number: | 2644 |
| Available to public: | no |
