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PR1_5001_A01 Page 6 of 8
4. While maintaining the separation between the PR1 unit and the test pinger, slowly adjust
the frequency control back and forth to find the setting which registers the highest signal
strength on the Signal Strength Meter. Turn down the sensitivity if the signal strength
reaches full scale. Confirm that a clear signal is being received and that the frequency and
pulse rate are as expected.
5. Turn the pinger OFF and ON multiple times and confirm that the received signal follows
this behaviour.
6. Connect the supplied earphone connector to the Earphone Jack on the PR1 faceplate.
Confirm that a “Chirp” can heard through the earpiece and that the pulse rate matches
that of the target pinger. The Volume Control Knob should be adjusted as required.
7. Providing all the steps above were completed successfully, the unit has now passed the
function test.
3.2. PR1 DEPLOYMENT AND OPERATING INSTRUCTIONS
Prior to deployment, the unit should be charged overnight to ensure that the batteries are at
fully capacity.
Ensure that a function test has been completed (see SECTION 3.1 above) prior to deployment.
This is to make sure that the unit is working correctly and to ensure that the operator is
acquainted with the operation of the device.
For best results, the supplied earphone should be connected and the audio signal used in
conjunction with the Signal Strength Meter to locate and identify signals.
As with all acoustic systems, ambient acoustic noise in the environment will have a significant
impact on the performance of the PR1 unit. Some of the most common sources of ambient
acoustic noise are vessel engines, water turbulence and rough weather.
Also be aware that there may be nearby acoustic sources unexpectedly transmitting at the
frequency of interest. These should be disabled if possible. For example, any acoustic beacons
on any ROVs must be disabled and any support vessels with dynamic positioning systems
should be disabled or configured to work outside of the frequency of interest if possible.
The typical procedure for locating an acoustic pinger is given below. This procedure assumes
that the operator knows the expected frequency and pulse rate of the target pinger.
1. Turn the unit on by rotating the Volume Control Knob clockwise. There should be a
noticeable click at the beginning of travel and the LCD in the centre of the front panel
should illuminate and display the current frequency setting. Continue rotating the
volume knob until it reaches its limit at which point the volume has been set to
maximum.
2. Adjust the receiver frequency setting using the Frequency Control Knob until the
frequency of the target pinger is displayed on the LCD Frequency Display. Note that
the bandwidth of the receiver is approximately 2kHz, so it will detect pingers
transmitting at frequencies within ±1kHz of the centre frequency displayed on the LCD.
However, the received signal strength will be greater when the centre frequency is set
to the same frequency as the source.
3. Adjust the receiver sensitivity control clockwise until a background noise level of
approximately 30% is registered on the Signal Strength Meter (this is typically the
optimum setting for identifying an acoustic signal). It will be extremely difficult to
detect a signal if the background noise is more than 70%. If the background noise is
more than 70% then the sensitivity should be reduced or the source of the excessive
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