STC SmartScanIS, User Manual

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14 January 2021, SmartScanIS User’s Guide for Union Pacific, EUD-2016026-00 Rev.2
Scanner mounts attach to the rail in a way that ensures that the scanners are:

Correctly aimed

Easily re-aimed, if necessary

Isolated from as much shock and vibration as possible

Electrically isolated from the rail
The scanner mounts can be installed on either rail, eliminating the need to maintain left-rail
and right-rail models. However, bearing scanner mounts and wheel scanner mounts are
different in design. They can't be directly interchanged. Nevertheless, they contain many
common parts, which mean that fewer spare parts need to be kept on hand.
Within each scanner is a pyrometer that measures the change in the amount of infrared
radiation emanating from the point at which it is aimed. As the amount of infrared radiation
increases, the output from the scanner increases proportionally. This increase is expressed
as a positive-analog voltage.
The scanner generates a signal as it is exposed to a passing heat source, such as heat from a
bearing or wheel. The ambient reference is obtained from the bottoms of the vehicles as they
pass over. The waveform of the heat signal is an electrical representation of the heat
generated by the passing bearing or wheel with respect to the ambient reference.
The heat signal travels from the scanner through the cable to the SmartScanIS enclosure. It
then passes through the Scanner Interface board to the System Interface board. Here, the
amplitude of the heat signal is scaled to represent an accurate representation of the
temperature. Next, the heat signal passes to the Processor board, where it is digitized for use
by STC's dynamic-scan-rate algorithms.
The dynamic-scan-rate algorithms assure collection of samples every 1/2 inch
(1.27 centimeters) of axle travel regardless of train speed. The heat signal waveform is
always sampled 48 times between the gating transducers. It makes no difference what speed
the train is going, as long as it is traveling from 7 to 90 mph (11.3 to 145 kph).
A benefit to using these algorithms is the creation of a digital filter within the firmware.
Sampling every 1/2 inch (1.27 centimeters) assures that no valid heat is missed, but timing the
sample rate creates relatively long periods when no samples are being taken at all. This
period acts as a filter for undesirable noise-induced signals. In other words, use of these
algorithms contributes to better detection of alarm conditions with fewer false readings.
To avoid errant heat readings caused by moisture on the pyrometer lenses, the scanners have
heaters built into them. The heaters are made active, for varying periods of time, when the
ambient temperature is 80°F (26.7°C) or less.