2.5. SIGMA AUDIO
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2.5 Sigma Audio
The Ludlum Model 3014 has the standard "click" audio that is widely used by radiation in-
struments; however, it also has a Sigma Audio mode that can be enabled to change the audio
sound. This mode is useful for scintillation detectors because their high count rate makes
the "click" audio less useful.
In the sigma audio mode, the instrument measures the background radiation for eight sec-
onds on power-up, and then automatically sets a low threshold alarm rate above the back-
ground rate. Then the instrument will produce a beep any time that the instrument "sees"
more than this threshold value. The user doesn’t need to watch the display to find a small
increase over background; the user may just listen for multiple beeps. Thus, the unit has
an audio alarm that, on power-up, adjusts to just above the current background level and
provides a sensitive audio indication to the user.
Note that this audio alarm can also work in conjunction with the fixed alarm, i.e. the user
can have both a floating audio alarm (resulting in audio beeps) based on the background
level, and a fixed tone audio and a steady ALARM icon when a predetermined fixed alarm
level is exceeded.
2.6 Detector Failure Diagnostic
Note that the Model 3014 has its own diagnostic tests to ensure that the detector is function-
ing correctly. The Model 3014 can detect when the radiation detector is malfunctioning and
will flash the display to indicate a fault.
2.6.1 Detector Loss of Count
If the detector stops detecting radiation for a settable number of seconds, the Model 3014
will flash a zero reading for the currently selected units. This indication is common if the
unit is powered up without a detector connected. If this indication is observed with a con-
nected detector, remove the unit from service and have it evaluated by a qualified repair and
calibration technician.
Figure 2.6: Detector Loss of Count Display (Display Will Flash)
March 2021
