Sigma AM-255 Manuale Di Servizio

APPENDIX B.  GLOSSARY page21

 

 

Model AM-255 

Rolling Background:  This is the background accumulation method used in most of TSA’s 

instruments.  Background accumulation is done in ten separate buffers, each buffer represents 

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 a threshold, usually adjustable, that determines 

the highest signal level that will be accepted as a nuclear pulse by the system’s electronics.  Also 

see LLD.