Appendix C - Product Signal Tracking Menu - Loma IQ2 User Manual

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Appendices
Appendix C – Product signal tracking menu
This facility allows the detector to automatically adjust the working threshold between two
pre-set limits to enable the sensitivity of the detector to be optimised in situations where the
product signal drifts up and down with the change in product effect.
For instance, for a frozen product the product effect is very small when the product has just
come out of the freezer allowing a low working threshold level to be used giving a high
sensitivity to metal contaminants. However, if the line stops for any reason then the product
could thaw slightly, or if the product were not fully frozen, a significant product signal
increase would result. In this event the working threshold will have to be raised to allow the
product to be passed, without false rejection. Raising the working threshold to allow softer
product to pass without false rejection will reduce the sensitivity to metal contamination, i.e.
larger pieces of metal will now be detected. If the product becomes hard frozen whilst the
raised working threshold is still set the sensitivity to metal contamination will remain reduced
because the working threshold is higher than it now needs to be.
Tracking works by recording the product signal for each pack. From the values read the
working threshold continuously trends upward or downward between an upper and a lower
limit. The rate and amount by which the working threshold changes together with limits
between which it operates are controlled by user entered parameters.
It must be understood that this type of system may allow metal contamination that would
otherwise be detected when the product is fully frozen, to be accepted if product softening
has forced the working threshold to rise.
Operating conditions
The Tracking limits menu is only available if Tracker has been set to ON in the User
options menu. For this option to be available, a photo-eye must be fitted for product
registration purposes.
Tracking is product relative, ie the function can be turned on or off for each of the 100
product memories each memory can contain unique settings.
Tracker initialisation will occur whenever:
• The detector is powered on.
• The running product is changed.
• The Tracking limits parameters are changed.
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