RadEye PRD-ER
DB-066 E
3-9
Iw/Tr/Ff 06.07.2015
count rate of the background ratemeter according to the fol-
lowing empirical equation:
T
T
Cnt
n
Cnt
As
/
80
1
+
⋅
⋅
+
=
where As1: Alarm threshold 1
Cnt:
Count rate of the background ratemeter
T:
4 s, Time of measurement sliding window
n:
sigma value set between 2 and 9
The alarm threshold As1 is next compared to a minimum
count rate to alarm value As(min).
Condition
Active alarm threshold 1
As1
≥
As(min)
As1
As1 < As(min)
As(min)
Recommended Sigma value and As(min) settings:
Sigma = 6 enables almost false alarm free searching in areas
with a fairly constant radiation background.
For general use, especially in an urban environment the setting
of a As(min) in the range of typically 20cps – 60cps is rec-
ommended to avoid false alarms from certain natural materi-
als
1
. The factory setting
2
for As(min) = 30 cps.
1
Frequently paving stone and plates made from granite contain sub-
stantial traces of Uranium and Thorium.
2
Please note that the value for As(min) can’t be changed in the
RadEye’s menu, but requires the RadEye a PC connection and the
software RadEye.EXE. As(min) is named in the software “Sigma
min Range [cps]”. Please refer also to chapter 6.4.3.