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4.2. LISTENING
While in LISTENING mode the unit continuously monitors the acoustic energy produced by the
pipeline as it waits for a pig passage to occur. The unit is configured to recognize the unique
sound signature produced by a pig as it passes the sensor. The unit uses the algorithm described
in section 4.4 DETECTION ALGORITHM to detect a pig passage.
While in LISTENING mode the display will be off and the LEDs above and below the display will
flash every five seconds to indicate that the unit is active. The relay and current loop outputs
will be in LISTENING state.
There are two things that may cause the display to change:
CONTROL BUTTON – If the control button is pressed the unit will enter the MENU system.
The menu system is described in section 4.5 SINGLE BUTTON MENU INTERFACE.
PIG APPROACH – If the unit detects a possible pig approaching
the sensor then the display will show a PIG APPROACH message
as shown. From this point the unit will continue running through
the detection algorithm until either the approach is cancelled, in
which case the display shall turn off, or it will signal pig detected
as per section 4.3 DETECTION.
4.3. DETECTION
When a pig is detected the display will show a PIG DETECTED
message including the time and date of the event as shown. The
LEDs above and below the display will flash every second and the
relay and current loop will be in the DETECTION state. The time
and date of the pig passage are stored in internal memory and
can be viewed later using the menu interface.
The unit will remain in the DETECTION state for the length of time defined by the OUTPUT DELAY
before returning to LISTENING mode. The OUTPUT DELAY can be bypassed by pressing the
CONTROL BUTTON.
OUTPUT DELAY – The OUTPUT DELAY controls how long the unit will signal an event for. Usually
it will be configured to give the pig enough time to get out of range of the sensor after it has
been detected to avoid re-trigger. When dealing with pig trains, the expected pig speed and
separation should be used to configure a suitable value for the OUTPUT DELAY such that the unit
will not detect the same pig twice but will enter LISTENING mode in time to detect the next pig.
LATCHED DETECTION – If the OUTPUT DELAY HH (hours) field
is set to 99 then when an EVENT occurs the unit will LATCH in
DETECTION mode showing the EVENT information and flashing
the LEDs every 1 second. To begin LISTENING again the CONTROL
BUTTON must be pressed or the detection reset using the serial
interface.
ID5001P_5001_B00
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