>>Interesting. But I didn't quite understand: What were those measurements for? Calibration of what?
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>Hilmar;
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>I hope this answers your question. Manufacturing requires adherence to International Standards, which are recognized and agreed upon by the countries involved. In the case of Metrology, you are required to measure any physical quantity or quality. It can be a basic physical measurement such as but not limited to resistance, time, length and frequency. Frequency for example was an area where we had an in house standard good to better than 2 parts in 10 –11(excuse the lack of superscript). Physically, we could measure accurately to within about a micron.
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>In the case of audio and video tape recorders; you want to ensure the ability to reproduce sounds accurately as far as level and frequency reproduction. These devices are used in professional recording environments and not what you or I would buy off the shelf for home use.
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>As an example an audio tape deck may have a speed of 15 ips (inches per second). If the motor does not track at the correct speed it will change the sound. By playing a calibration tape you record the frequency output to determine the speed of the system. These tapes also help to analyze other parameters to determine the quality of a tape deck (recorder).
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>If I did not answer your question please let me know. It is too easy to "get lost" and side tracked when I start discussing such topics.
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>Tom

Interesting again. Thanks, and yes, I think this answered my doubts.

Hilmar.