Rapiscan TSA TPM-903B Operation And Service Manual - 7.0 Glossary
TSA TPM903 Operations and Service Manual
Doc: # 5058 Rev. A
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7.0 GLOSSARY
ADC: Analog to Digital Converter is an integrated circuit that converts an analog signal into a
binary number than can be used by the microprocessor.
CPS: Counts Per Second
High Background Alarm/Fault: The condition that occurs if the counts exceed the programmed
high background level. This condition prevents further operation until the problem is corrected.
Normally set in CPS.
LCD: Liquid Crystal Display
LED: Light Emitting Diode
LLD: The Lower Level Discriminator provides an adjustable threshold that determines the
lowest signal level that will be accepted as a nuclear pulse by the system’s electronics. Some
systems have both upper and lower level discriminators that can be used to set a discriminator
window. The discriminator window can be used to effectively reduce the background counts, and
increase system sensitivity to certain isotopes.
Low Background Alarm or Low Background Fault: The condition that occurs if the counts
fall below the programmed low background level. This condition prevents further operation until
the problem is corrected. Usually set in CPS.
POST: Power On Self-Test
Rolling Background: This is the background accumulation method used in most of Rapiscan’s
instruments. Background accumulation is done in ten separate buffers, each buffer representing
1/10 of the total background time. As each buffer is filled, the background is updated. This
results in a background update at background time/10. Initial background accumulation requires
the full background time.
Standard Background: Standard background requires the full background time for the initial
background and updates.
ULD: The Upper Level Discriminator provides an adjustable threshold that determines the
highest signal level that will be accepted as a nuclear pulse by the system’s electronics. Some
systems do not have an ULD. Also see LLD.