Setup For Correlation Recordings - Method 1; Setup For Correlation Recordings - Method 2 - FCS PCorr+ User Manual

Correlation requires that the loggers simultaneously record the sound from various
points along the pipeline. Since the correlation process is very sensitive to time
differences between the devices, the recording and the collection of the sound file must
occur within a day (before the clock of each device has drifted far from its original
accuracy).
For the greatest positional accuracy, use of specialist correlation equipment that
evaluates live audio is recommended, such as HWM's MicroCorr Touch Pro Correlator.
With PCorr+, results are improved when the recording is made and collected as soon as
possible after the scheduled recording is programmed. Always use a ground
microphone to confirm the leak location prior to commencing repair works, such as
HWM's DXMic ground microphone.
A scheduled sound recording needs to be programmed into each logger in the set. The
procedure required to ensure the logger clocks are aligned will vary according to the
application being used and also the model of patroller being used.
Note: The logger devices must have a patrol window available in order to be able to
collect the sound files. The files must be collected without a reset of the logger
(which disrupts the internal timekeeping of the device).
4.2.1 Setup for Correlation Recordings – Method 1
The USB Transceiver type of Patroller requires all loggers to be brought together (within
radio range) and programmed as a set. Similarly, the loggers need to be brought back
together as a set to download the audio. The time accuracy of each logger is checked by
the app following file download to confirm it is OK for correlation use. This includes
whether any of the devices have been reset since they were set up.
Whilst the sound recording is pending, some normal logger operations are suspended,
but will resume when the recording is completed. (See section 2.12.)
4.2.2 Setup for Correlation Recordings – Method 2
When the patroller being used to program the loggers has a high-accuracy time
reference within it (e.g. Patroller 4, when GPS sync is OK), the possibility exists to set the
clock within each of the loggers accurately, one at a time.
(i.e. There is no need to gather them together; dependant on software support of this).
12