Ocean Instruments SoundTrap ST400 User manual

SoundTrap ST400 User Guide
September 2021

1 About this guide ..............................................................................................................................4
2 Quick start guide .............................................................................................................................5
2.1 Opening and closing the housing.....................................................................................5
2.2 Batteries...........................................................................................................................6
2.3 Memory............................................................................................................................7
2.4 Install the SoundTrap host on your PC.............................................................................8
2.5 Connect SoundTrap to your PC........................................................................................8
2.6 Check SoundTrap Status ................................................................................................10
2.7 Configure the deployment.............................................................................................10
2.8 Begin recording using the IR Remote Control................................................................12
2.9 Data Offload...................................................................................................................13
3 More details ..................................................................................................................................14
3.1 Data Files........................................................................................................................14
3.2 Calculation of deployment endurance...........................................................................15
3.3 Clock details ...................................................................................................................15
3.4 Deployment hardware ...................................................................................................16
3.5 Software updates...........................................................................................................16
3.6 MSP firmware updates...................................................................................................17
3.7 Troubleshooting.............................................................................................................17
3.8 Calibration......................................................................................................................19
4 Appendices....................................................................................................................................20
4.1 SoundTrap HF Click Detector (ST400HF Only)................................................................20

4.1.1 Click detector..........................................................................................................21
4.1.2 Snippet extractor....................................................................................................21
4.1.3 User parameters.....................................................................................................22
4.1.4 Output File formats ................................................................................................23
4.1.5 Click Detector Caveats and Cautions......................................................................24

1About this guide
This guide begins with a ‘Quick start’ section to help you get going with your new SoundTrap, including
software installation and basic deployment instructions. This is followed by several sections containing
more detailed information around operation, deployment, maintenance and troubleshooting. It is
highly recommended you read the entire guide to ensure you have a good understanding of the
instrument and how to get the most from its capabilities.

2Quick start guide
2.1 Opening and closing the housing
Before opening an underwater housing always check for flooding by shaking and listening for
water sloshing around inside. If flooding is suspected, then be aware that the housing may be
pressurised and therefore hazardous. Carefully relieve any by wring the housing in a towel and
opening at arm’s length.
Opening the housing:
•Dry the with a towel so housing is completely dry before opening.
•Hold recorder with the hydrophone facing downward to ensure any remaining water won’t
run down into the housing.
•Twist the housing anticlockwise to release the lock.
•Gentry pull the chassis from its housing.
Closing the housing:
•Carefully check the O’rings. Any nicks or scratches indicate they must be replaced.
•Lubricate O’rings with silicone grease.
•Check O’rings are properly seated and absolutely free of stray hair/grit etc
•Insert the chassis in the housing.
•Lock the housing closed by turning the chassis clockwise until end of travel.
•Where heavy fouling is likely to occur, we recommend sealing the gap by means of a couple
of turns of insulation tape (figure 2).
•Replacement O’Rings should be type 48x3 N70 (Nitrile)
The O’ring checks are critically important to avoid damage. Any detritus or damage to the O’rings
may result in the housing being flooded which will almost certainly destroy the electronics.

2.2 Batteries
BATTERY WARNING. Lithium ion batteries may explode or burn due to improper use. Careful
attention should be paid to your battery suppliers safety recommendations.
The SoundTrap ST400 is powered by 2 Panasonic NCR18650B (flat top) lithium-ion batteries. These
are loaded individually, meaning you can use one or two batteries. However we recommend loading
both batteries to provide a level of redundancy.
We strongly recommend only using Panasonic NCR18650B (flat top) batteries. These are commonly
available and all testing and advertised battery endurances assume use of NCR18650B batteries.
Performance of other brands is unknown. Untested brands may leak acid, potentially causing
damage to the electronics. Source the batteries from reputable suppliers to avoid inferior
counterfeits.
Be careful to ensure correct battery polarity as indicated by the diagram in the battery
compartment. Once loaded, double check each battery’s polarity.
18650 batteries are generally supplied in a partially charged state and should be recharged prior to
first use. Recharging requires a good quality lithium-ion battery charger such as the XTAR VC4 or
similar.
When not in use, batteries should always be removed from the recorder and stored in a fireproof
container. If the batteries are not to be used for a long period (more than a month) they should
ideally be stored in a half-charged state in order to maintain future performance.

2.3 Memory
The SoundTrap ST400 series have capacity for up to 4 microSD cards.
Important things to note about memory:
1. You should only use the recommended memory cards –Samsung Evo MicroSD (up to
512GB). Counterfeits of these cards exist, so only source from reputable suppliers. Using
other card types or counterfeits may result in performance issues such as increased power
consumption, sampling gaps or unreliable recording.
2. The cards are used in the sequence 4->3->2->1 where 1 is the top-most card. Any full or
missing cards will be skipped.
3. It is critical that each card is formatted prior to each deployment. This can only be done in
the SoundTrap recorder using the ‘Delete All Files’ option. This must be done for each card
individually.
4. SoundTrap uses a custom file system to maximise performance and reliability. This means
the cards can only be read with the ‘SoundTrap Card Reader’ application supplied with the
SoundTrap Host software. When inserting the memory cards into a PC you may receive a
message like “Drive is not formatted, do you want to format it now?”. Agreeing to this will
result in loss of data. Instead select ‘No thanks’ and run the SoundTrap card reader
software.

2.4 Install the SoundTrap host on your PC
To start using your SoundTrap you’ll need to install the SoundTrap Host software.
For correct operation of your ST400 it is critical to use SoundTrap Host version 4.0.0 or
later.
•Pre-installation Notes:
oThe SoundTrap host software supports Windows 7, 8 & 10 (32 or 64 bit versions).
oDo not connect the SoundTrap to your computer until you have completed the
SoundTrap host software installation.
oThe installation will be smoother if you’re logged into windows as an administrator.
•Visit www.OceanInstruments.co.nz/downloads/ to download the software.
•Download and run the installer.
•Once the install completes, run the SoundTrap Host application.
2.5 Connect SoundTrap to your PC
•Connect the SoundTrap using the USB cable provided.
•The drivers will take a couple of minutes to install. Once complete you should see your
SoundTrap appear in the ‘Device List’ on the left, as shown in figure 3.
•Select your SoundTrap by clicking its label on the left.

Figure 1 - The Device List

2.6 Check SoundTrap Status
Note the ‘Status’ panel on the right (Figure 4). Carefully review the state of memory and
batteries in the right-hand pane, checking that all batteries show 100% charge and all
memory show 0% used.
Figure 2 –Deploy Control
2.7 Configure the deployment
•Select the ‘Deploy’ tab as shown in figure 4.
•Configure the deployment parameters as follows:
oThe ‘Recording Starts’ section determines when recording will begin. Recording can
begin immediately on disconnection of the USB cable, at a pre-determined date and
time, or manually using the IR remote control. Note that the remote can always be
used to override the other options.

oThe ‘Recording Schedule’ section provides selection of continuous or periodic
recording. For continuous recording simply leave the ‘Periodic Recording’ option
unchecked.
oOptions available in the ‘Audio Options’ will vary according to your device’s
capabilities. Options include the following:
▪Channel Selection selects which channels to record on.
▪Sample Rate should be set based on the frequency band of interest and
data rate considerations. A 96 kHz sampling rate is often a good choice for
general environmental noise measurements. Contact OI support if unsure.
▪Preamp Gain should usually be set to ‘High’. This will result in a maximum
SPL before clipping of approximately 175 dB re 1 uPa. The ‘Low’ setting
should be used for very noisy environments such as in the vicinity of pile
driving. The low setting increases the maximum SPL to around 187 dB, but
comes at the cost of lower sensitivity.
▪High pass filter. This should usually be turned off. This only used in
very high energy sites or when towing a SoundTrap behind a boat. Turning
this on reduces sensitivity in the band 0 to 600 Hz, while leaving higher
frequencies unaffected.
oDetector –see HF Click Detector section below.
•Click the deploy button which will save the settings and you’re ready to go. If you change
your mind about something, just re-select the instrument from the ‘Device List’.
•The instruments internal clock is synchronised to your PC when you click the deploy button.
Note that the recorders clock requires at least one battery to be installed to keep time
once the USB is disconnected.

2.8 Begin recording using the IR Remote Control
You may use the remote control to start recording. The
recorder housing must be open to receive the signal from the
remote.
•Press ‘START’ to start recording.
•Press ‘STOP’ to stop recording.
•If you have set a recording to start recording at a
later time, the recorder will blink red to indicate it
is ‘armed’ and waiting.
•The ‘armed’ state is cancelled by pressing Stop key.
•Re-enable the armed state by pressing the ARM
button.
•You can verify recording has started by checking for slow blinking of the status (green)
indicator.

2.9 Data Offload
Once you’re done recording, reconnect your SoundTrap to your PC and select the Retrieve Tab, as
shown in figure 5.
Figure 3 –Retrieve Tab
•Each memory card can be selected using the drop down list.
•You will see a list of files on the selected memory card, including the file name (made from
the device serial number plus local date and time), date recorded, approximate size and
whether it has yet been downloaded to your computer’s hard drive.
•Download individual files by right clicking the file and selecting ‘download’.
•By default, all files will be downloaded to a ‘SoundTrap’ folder under My Documents. This
default location can be changed under the ‘Tools’ menu.
•Click the ‘Open Save Folder’ button to open the download folder location.
•To download all files, select all files using the shift key, then click the ‘Download’ button.
•To delete, click the ‘Delete All’ button. Files cannot be deleted individually.

•For faster download in the field, or to save disk space, un-check the ‘Decompress’ checkbox.
This will disable the decompression step of the offload process, meaning you will end up
with ‘sud‘ files only. These can be decompressed into wav files at a later time using the ‘File
Extraction’ option under the tools menu.
3More details
3.1 Data Files
Downloads produce several types of files:
o‘sud’ files which are the raw downloaded file. This is a compressed file and therefore
ideal for storing or sending of complete recordings. It can then be decompressed at
a later time into the following constituent file formats.
o‘wav’ files containing the audio. This is a Microsoft WAV format file that can be
opened by any media player, matlab, raven etc.
o‘xml’ files which contain metadata such as date recorded, gain setting, etc.
o‘csv’ files containing ancillary sensor data (e.g. temperature)
All file types follow the same naming convention consisting of the device serial number followed by
the date and time of the start of the recording in the format YYMMDDHHMMSS.
For duty cycled recording there will usually be one file per recording period. For continuous
recording a maximum file length of 1036800000 samples (2GB of wav) will determine the length of
the files. This equates to 1 hour recordings for a 288khz sample rate.
Where smaller than 2G files are desired for continuous recording it is recommended to set a duty
cycle with ‘zero off time’. For example, a duty cycle of 30 minutes every 30 minutes will result in
continuous 30 minutes files with no missing samples between files.

3.2 Calculation of deployment endurance
An excel spreadsheet is provided on Ocean Instruments website to help with the calculation of
deployment times for differing deployment parameters. The spreadsheet provides deployment
estimates, as well as identifying one of three possible deployment constraints: battery capacity,
memory capacity, or file count. While the first two are obvious, the file count constraint requires
explanation.
The file system used by SoundTrap currently has a minimum file size of 4 MB. When using periodic
recording, if the programmed ‘record for a period of’ period is very short, the resultant file may be
smaller than the minimum file size. This will result in inefficient usage of memory, and the
deployment may be artificially memory limited. For example, a SoundTrap ST400 has 256 GB of
memory; dividing this by the minimum file size of 4 MB gives a maximum of 64000 files.
This limitation becomes an issue when using low sample rates in combination with X3 compression.
By experimenting with the periodic recording parameters in the deployment spreadsheet it will
become clear how to best avoid this limitation.
3.3 Clock details
SoundTrap’s clock is synchronised to your PC whenever you click on the ‘deploy’ button, with an
accuracy of +/- 0.5s.
Internally the clock is maintained in UTC time. When files are offloaded to the PC file times are
converted to local time (using the PCs location settings) for population of the filenames. This means
that the dates and times in the filenames are always in the time zone of the PC that was used to
offload the files. This can be important where files are offloaded in a region other than that in which
they were recorded. Alternatively, filenames can be assigned UTC times by selecting the ‘Use UTC
time’ option under the tools menu.
Like most electronic devices, SoundTrap relies on a crystal oscillator for time keeping. The oscillator
used in the ST400 has an accuracy of +/- 5PPM, or +/- 0.44 seconds per day. The audio sample rate is
derived from the same oscillator, meaning the sample rate is subject to the same accuracy. The
oscillator will drift with temperature with this range. For more information on the clock accuracy
please see documentation for the oscillator - SiTime part SIT1552AC-JE-DCC-32.768D.
Sampling rate accuracy is also subject to occasional sampling gaps. The nature of SD flash memory
cards is such that occasional the memory card will fail to keep up with sampling, thereby resulting in

dropped samples. When this occurs, an entry will be written to the log (xml) files in the format
“sampling gap X us at sample Y”. There is an experimental option under the Tools menu ‘Zero Fill
Dropouts’. This function will attempt to fill any sampling gaps with a series of zeros. This may be
useful where more precise sampling timing is required.
3.4 Deployment hardware
The anchoring scheme used is very dependent on the goals of the data collection in combination
with the deployment environment. Thankfully SoundTraps are more easily deployed than traditional
acoustic recorders due to their small size. A SoundTrap ST400’s weight in water is approximately 0.2
kg.
Most often the hydrophone is located near the sea floor, using an anchored line. This involves
running a line between a heavy anchor weight and either a surface or sub-surface float. A sub-
surface float is often best, as it is less affected by weather/swell and is less likely to be tampered
with. The SoundTrap should be attached to the line a couple of meters off the bottom. Two grooves
around the housing provide attachment points for cable ties. This bottom cable tie should pass
through the associated hole so it cannot slip off.
Avoid using the hydrophone cage as an attachment point. This is too close to the hydrophone and
may introduce unwanted noise into the recordings.
Be mindful that a taut line combined with strong currents may result in ‘cable strum’ which may
disrupt your recordings. In this case a rigid frame may be more appropriate.
Ensure there are no metal objects in close proximity (3cm) to the SoundTrap eg using metal brackets
or wire rope. Doing so may lead to galvanic corrosion of the instrument housing.
Don’t mount your SoundTrap so close to the sea floor that it may become covered in sand or mud.
This may also lead to corrosion and corrosion instrument housing.
3.5 Software updates
New software releases will be made available via the Ocean Instruments website. You may which to
subscribe to our email list in order to receive notification of these updates. The update procedure is

generally straightforward –simply install the new software over top of the existing, by running the
msi file and following the usual Windows software install prompts.
The software updates will typically include updates to both the windows software as well as the
device firmware. The updating of the device firmware is an automatic process that occurs when
pressing the ‘deploy’ button.
3.6 MSP firmware updates
From time to time a software release may include an update to the ‘MSP’ firmware. This is a special
section of the device firmware that changes infrequently. In the rare event that an MSP update is
required, the user will be advised during the deploy procedure and will be asked to hold the ‘reset
switch’. This is a security feature that ensures the MSP
firmware cannot be unintentionally modified. The reset
switch is somewhat hidden - it is located adjacent #3
memory card slot and is activated by inserting a pin through
a small hole in the electronics cover.
When asked to ‘press reset’ you must hold down the reset
switch. Once the switch is held down you can click the OK
button (may require second person!) as per the software
instructions. You will then be asked to release the reset switch. This done, the MSP firmware update
will proceed and complete within a few seconds. If presented with the error message “MSP Erase
failed”, it is likely that the pressing of the reset button was interrupted –please try again.
3.7 Troubleshooting
First port of call when experiencing problems is to check that you are using the most up to date
software. Oftentimes small issues are most easily resolved by updating the software –please try this
first. The latest software can be downloaded from here:
www.OceanInstruments.co.nz/downloads/
Problem: SoundTrap doesn’t appear in device list when plugged into computer
Figure 4 - Location of reset switch

Solution: Please try removing all memory cards and lithium batteries. Then disconnect and reconned
the USB cable. If this resolves the problem, try reloading each of the memory cards and batteries to
see which one is causing a problem.
Problem: Offload process reports errors and produces smaller than expected files.
Solution: This indicates errors with USB communication. Common causes include:
1. Using a external hard drive on the same set of ports - this can overload the USB controller.
2. Using a USB hub - try connecting directly to the computer
3. Using a low-quality laptop - try a better computer
Problem: IR Remote is not working.
Solution:
1. Check that it has a battery. These are not suppled due to shipping restrictions. Correct
battery type is the commonly available CR2032. Be sure to remove the plastic insulator
sheet before inserting the battery.
2. Ensure that you are pointing the remote directly at the recorders electronics module.

3.8 Calibration
Each SoundTrap is factory calibrated from new. The standard factory calibration consists of a piston
phone calibration at 250 Hz, performed for both low and high gain settings. The calibration data is
not shipped with the hydrophone, but instead made available online from the calibration page of
the Ocean Instruments website http://www.oceaninstruments.co.nz/
The calibration data is provided as an end-to-end value. This measure is provided for both high and
low gain settings, and represents the SPL that will result in a normalised (±1.0) wav file with a
fullscale signal ie 2.0 units peak to peak.
Note that in contrast to traditional hydrophone systems, with SoundTraps there is no need to be
concerned with sensitivity in voltage terms. Because SoundTraps integrate the recorder and
hydrophone in a single package, there is a fixed relationship between sound pressure and the
resultant wav file data, thereby simplifying calibration and eliminating the need for voltage
calculations.
Application of the calibration data varies depending on the software used. Descriptions follow for
some of the most commonly used software.
MATLAB
To convert wav data to units of uPa, simply scale by the end-to-end calibration value. Example code:
[y, Fs] = wavread(filename) ;
cal = 173.3;
cal = power (10, cal / 20);
y = y * cal;
% read wav data from file
% value from calibration sheet
% convert calibration from dB into ratio
% multiply wav data by calibration to convert to units of uPa
PAMGUARD
PAMGAURD expects calibration data in terms of gain and ADC range. To work around this, specify a
preamplifier gain of the calibration value * -1.0 (eg -176.0) and specify the Peak-Peak voltage range
as 2.0 V.

PAMGuide
PAMGuide provides several convenient calibration schemes. For SoundTrap data select the end-
toend calibration type and enter a system sensitivity of the calibration value * -1.0 (eg -176.0).
Audacity
Audacity reports SPL in units of dB re full scale. To scale SoundTrap data use the following:
Value in dB re 1 uPa = audacity value + end-to-end calibration –3dB;
For example, if the end-to-end value from the calibration sheet is 176.0 dB, and audacity reports a
level of -70 dB, the calibrated SPL is 103.0 dB re 1 uPa.
Calibration Tones
By default, a series of calibration tones will be audible at the beginning of each recording. These can
be used to check the calibration of the recording. After applying the calibration to a recording, the
SPL of the 1 kHz tone should be equal to the calibration tone level stated on the calibration sheet.
If the calibration tones are an annoyance, they can be disabled on the deploy tab. However, we
recommend keeping them enabled where possible as they provide a useful check of system
calibration and performance.
4Appendices
4.1 SoundTrap HF Click Detector (ST400HF Only)
The SoundTrap ‘HF Click’ Detector is a general purpose high frequency click detector followed by a
snippet extractor. The detector is designed to detect most odontocetes and is intended to be used
as a first pass, guiding you to times in your recordings with lots of transients. You would typically use
the detector with a low detection threshold so that it makes a lot of false detects but also detects
most genuine clicks (i.e., high sensitivity, low specificity). You then evaluate the reported detections
in Pamguard to reduce obvious false detects, to classify clicks into species groups, and to identify
bouts, as you would with a continuous wideband recording. The benefits of doing on-board click
detection are that you get much longer recording times from your SoundTrap and you can identify