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Digital Speedometer for Police Vehicle Applications
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English
Abstract
Previously, a mechanically driven analog display speedometer was used for police vehicle applications. The speedometer required special processing to meet the tight accuracy requirements of ± 4.83 kph ( ± 3 mph) over a speed range of 32.2 kph (20 mph) to 160.9 kph (100 mph).
For the 1991 police vehicle, the speedometer accuracy requirements changed to ± 3.22 kph ( ± 2 mph) over the same range. This change, along with the speedometer design criteria, resulted in the change from a mechanically driven speedometer to a digital speedometer. This digital speedometer was packaged in an existing cluster design in a timely manner and for a minimal investment. Special design considerations included minimizing radiated emissions in the police band frequencies and allowing only the speedometer to be turned off during special nighttime driving conditions.
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Authors
Citation
Eldon, T., "Digital Speedometer for Police Vehicle Applications," SAE Technical Paper 930460, 1993, https://doi.org/10.4271/930460.Also In
References
- Speedometer and Tachometer Parts and Components, SAE Handbook 2 1992