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Maximum Dead Time Calculator

"Dead time" is the length of time any additional hits on a sensor are ignored after a valid strike.  It may be used to filter out extra signals from air pulse echoes or cars crossing the sensor at an angle.  But dead time cannot be set too long.  Otherwise, good strikes will also be ignored.

The TimeMark system allows you to adjust the dead time either before you record your study (in the counter) or afterwards (software dead time).  Using the software dead time is usually preferred because you can adjust it without affecting the original data.  Strikes that occur during the counter dead time are not saved and cannot be recovered.

This calculator tells you how long you can set the dead time without losing any real axle strikes.  It assumes there is only one lane of traffic.  If a tube crosses two or more lanes, a second vehicle could strike the sensor at any time after the first one.

Measurement System
Shortest distance between any two axles  inches
Maximum vehicle speed  mph
Dead time should be less than49 ms

Warning sign Warning!  Counter dead time is an advanced setting.
If it is set incorrectly, data will be permanently lost.  Properly securing your tubes to the roadway and using the software dead time are usually better options for improving the quality of your data.  Before changing the dead time in your counter, please contact TimeMark Technical Support.

Notes:
  • The software dead time only works with time stamped event data.  For Lambda or Delta I, II, and III counters, this means the file must have been recorded in Raw or Raw Data mode.  TimeMark Betas only record in axle volume mode, so the software dead time has no effect on those files.
  • If you connect to an older counter with VIAS 1.x, the counter dead time is in ticks, not milliseconds.  To get the dead time setting for those counters, divide the maximum dead time calculated above by the conversion factor for the model—
     * Delta III, Gamma, Beta, or Lambda:  3.66
     * Delta I or Delta II:  1.22
    VIAS 2 shows counter dead time in both milliseconds and ticks (when applicable).

Technical Support

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