12
ambient background level or in slightly longer periods of time with an increasing
ambient background level. However, the instrument will automatically recalibrate
itself only if there are no alarms or abrupt background changes over the algorithm-
defined periods of time.
Bear in mind that false alarms (audible or light) are sporadic and are easily
distinguished from true alarm signals which tend to be continuous or increase as the
instrument moves closer to a radiation source.
When a radiation source is detected, the operator may locate it. To locate a
radiation source, hold the instrument at a distance 10 cm or closer from the scanned
object, the scan velocity should be 10 cm per second or slower. As the instrument
moves closer to the radiation source, the rate of alarm signals increase. When the
alarm signals reach the maximum rate pinpointing the source more closely is
impossible without updating the background. Keeping the same distance to the
scanned object press and hold the MODE button 12 or button 10 (Fig. 1) (if the
headphones is used), until “CAL” is displayed to start the calibration sequence. The
alarm threshold is automatically adjusted to the new baseline locating the source may
be resumed. It may be necessary to repeat this procedure several times until a
radiation source is located.
2.2.4 Settings
To enter this mode press and hold the MODE button 12 (Fig. 1) for more than
4 seconds. Shortly press the MODE button to select a parameter to be set:
−
check the preset or set a new value of coefficient n (number of meansquare
deviations). The setting rage of the coefficient n is from 1 to 9.9 in 0.1 steps;
−
check the status of the built-in audible alarm and/or headphones audible
alarm and change it (switch on/off), if this is enabled in the PC communication mode.
2.2.4.1 Setting the Coefficient n
To set the coefficient n press and hold the MODE button 12 (Fig. 1) for more
than 4 seconds to enter the Settings mode. The LCD will display “CAL” message and
then the preset value of coefficient n.
