Laser beta lasermike LS8000-3 - Manual (Page 33)

LaserSpeed 8000-3 Instruction Handbook
Installing the System
Part No. 93463 / Drawing No. 0921-01561 Page 33 of 221 Revision A (Sep 2007)
Starting/Ending Length Correction
The Validation Time Limit feature is used because the Material Present signal
tells the gauge that material is indeed moving through the measurement zone.
If valid velocity measurements cannot be made, then a small amount of length
will not be accumulated which, in turn, will cause a length error. This may or
may not be a problem, depending on the velocity of the material when it
passes through the measurement volume during this time. The start-up
length-correction is executed to obtain a more accurate length reading. Each
measurement update is divided into small subintervals. When the Material
Present signal is received within an update period, the time it was received is
recorded with a subinterval clock. The length is calculated by using valid
velocity and integrating over the time measured with the subinterval clock. For
example, if the material speed is 10 meters per minute and material enters the
measurement volume in the middle of the 1-millisecond update period, the
subinterval time of 0.5ms is used to calculate length rather than the 1-
millisecond period. In this case, a 0.083 mm correction would be made. The
same type of correction is made when the material leaves the measurement
volume.
If problems are encountered during any of the installation steps, contact Beta
LaserMike for assistance.