SAIC Exploranium – GR-135 System Manual page: 19
6.3 NEUTRON ALARM
The system has a selectable Neutron Alarm Threshold (for settings see
Section 10.3). If this level is exceeded a distinctive audio warning tone
occurs and the display changes (fig 8).
This display will stay on the screen as long as the Neutron data is above the
threshold and for 5 seconds after the data drops below the alarm
threshold to ensure that the user can inspect the data adequately.
Fig. 8
6.4 SEARCH ALARM
If the ALARM LEVEL parameter (section 10.1) is set to a preset value and
the radiation field exceeds this value, a distinct audio beep will be heard and a
pop-up box will appear as shown in the figure. As the user moves away from
the source the audio and pop-up display will go away.
Fig. 9
6.5 SEARCH - AUDIO
In the SEARCH mode the radiation data from the high-sensitivity Sodium-Iodide (NaI) detector is
used to create an audio search capability thus permitting the user to have an “eyes-free”
operational mode. It is very difficult to scan a vehicle and inspect the display continuously.
The GR-135 scans the incoming data at a 20 TIMES a SECOND RATE – and converts the
radiation field into a mode that changes the frequency of the audio tone to reflect the radiation
field intensity. Various parameters are used (see section 10 for details) to adjust system
performance to suit the user. In the majority of cases the audio gives occasional “beeps” of low
intensity audio on normal background (this shows the user that the audio system is alive) but in
the presence of a real radioactive field the audio frequency changes rapidly. With this feature it
is very easy to scan back and forwards to readily locate the highest audio pitch which is the
maximum radiation intensity.
6.6 SEARCH MODE - DATA RECORDING
The data displayed during the SEARCH mode can be recorded in memory. Recording to memory is
implemented by menu selection in the SETUP - SEARCH menu (Section 9.1). When the “OUTPUT
TO” parameter is set to “MEM” and the SEARCH mode is started, the data is logged into memory at
the selected Sample Rate. The message SEARCH->MEM will be displayed at the top of the screen
during the SEARCH to indicate that the data is being saved to memory.
Data recording is terminated when the memory is full or the mode is stopped (ENTER). Every time
the SEARCH mode is stopped then started again, a new header is written so the data can be
retrieved later with the appropriate time information. Remember that all SEARCH data will be loaded
into memory until the data recording option is disabled in SETUP mode.
The data memory can record approximately 45,000 readings at the selected data rate. Thus, at a
one sample per second data rate, the memory will hold almost 12.5 hours of SEARCH+DOSE data.
Once the GR-135 memory is full the message MF (memory full) will be displayed at the top of the
screen and the user gets a 3-beep audio warning and the SEARCH>MEM label is removed.
NEUTRONS
DETECTED
WARNING
ALARM
ABOVE
LIMIT
WARNING!!
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