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Inspect the O-rings for cracks, deformation, or flattening. They must be round and pliable. If they are square or stiff, replace them. Clean sealing surfaces, use only light silicone or O-ring grease, and avoid dirt or fibers.

If biofouling significantly overgrows the transducer, it has the potential to influence the receiver’s performance. Techniques such as anti-fouling paint or manual wash/scrub can be helpful, but more scientific backing in the area is required to guarantee the efficacy of such preventative measures.

Check O-rings and clean the unit before and after each deployment. Perform a functional test and visual inspection before redeployment. Full servicing is recommended if any damage or corrosion is observed.

The receiver uses Tadiran SL-2790 or TL-5937 lithium batteries. Typical battery life is up to 24 months, reduced to 18–21 months when using 2–3 frequencies.

Use protective gloves, glasses, and work in a ventilated area. Do not open the unit near people. Wrap the receiver in a towel and open slowly. If unsure, contact Thelma Biotel before proceeding.

This indicates internal pressure from possible battery damage. Handle the unit cautiously and follow battery safety procedures. The battery safety procedures can be found under Documents & downloads.

Hold the magnet to the magnet slot until the LED flashes blue, then remove the magnet. Bluetooth will stay active for 3 minutes.

Sleep mode is used to prevent unwanted detections between configuration and deployment. The receiver uses extremely low power in this mode and can remain in sleep mode for long periods with minimal impact on battery life.

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To put the receiver into sleep mode:

1. Hold a magnet to the magnet slot.

2. When the LED starts flashing, remove the magnet.

3. The LED will flash slowly 10 times.

4. Once the flashes stop and the LED turns solid, place the magnet back.

5. The LED will flash 3 × 2 times ("good-night" signal).

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To wake the receiver before deployment:

1. Hold a magnet to the magnet slot.

2. The LED will flash 3 × 3 times ("good-morning" signal).

3. Tap the transducer tip and confirm the LED blinks green – this means the receiver is actively listening.

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Always wake the receiver and verify it's listening before deployment.

The receiver always listens at a base frequency that must match your transmitters.

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• Single frequency: Listens only at the selected base frequency.

• Two frequencies: Listens at base + 2 kHz (e.g., 69 and 71 kHz).

• Three frequencies: Listens at base +2 and +4 kHz (e.g., 69, 71, and 73 kHz).

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Using multiple frequencies increases compatibility with more transmitters but reduces battery life:

• 2 frequencies → ~12.5% battery reduction

• 3 frequencies → ~25% battery reduction

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For custom frequency setups (not +2 or +4 kHz), contact us.

If the receiver doesn’t respond, try the following steps:

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1. Check if the receiver is in sleep mode

Tap the top of the receiver or place a magnet in the Bluetooth activation slot. If the LED flashes continuously, then slowly flashes 10 times before returning to continuous flashing, the receiver was in sleep mode. Remove the magnet after the flashing starts. If the magnet stays in place, the receiver may go back to sleep.

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2. Check battery orientation

Make sure the battery is inserted correctly. Incorrect placement will prevent the unit from powering up.

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3. Check battery voltage

Use a multimeter to measure the battery voltage if available. If not, try a different battery. If the receiver powers up with the new battery, the original may be depleted or faulty.

ComPort and LiveView are free to download. To receive the software:

1. Send an email to [email protected] or [email protected]

2. You will automatically receive an email with download links and installation instructions

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Once received, download the installation file(s) and follow the provided steps to install the software on your computer.

If you're unable to establish a Bluetooth connection between the TBR receiver and ComPort, consider the following:

• Bluetooth interference

Make sure Bluetooth is not active on multiple nearby devices, as this may cause connection problems.

• Receiver not in Bluetooth mode

The receiver must be manually activated with a magnet until the blue LED starts blinking. Without this step, it won’t be discoverable.

• Bluetooth not enabled on your computer

Verify that Bluetooth is turned on and functioning properly on your device.

• Driver or system issues

Some Bluetooth drivers or operating system settings may block the connection. Try restarting your computer or switching to a different device.

• Outdated ComPort version

Ensure you’re using the latest version of ComPort. If you’re unsure, contact Thelma Biotel for assistance.

Unknown IDs can appear due to several reasons:

• Signal collisions

When multiple transmitters ping at the same time, overlapping signals can result in false detections.

• High noise conditions

Environments with a lot of acoustic noise can interfere with decoding and increase the risk of invalid detections.

• Older protocols

Transmitters using older protocols are more prone to false detections because of a weaker checksum.

• Certain ID patterns

Some ID numbers are more likely to trigger false positives, especially those with many consecutive zeroes in binary format.

ACCELEROMETER_ALGORITHM: Thelma Biotel transmitters use the Activity algorithm, not Tailbeat. Tailbeat algorithms typically use only the axis most affected by tail movement, while Activity captures movement across all axes.

ACCELEROMETER_SAMPLES_PER_SECOND:

– RMS: 5 Hz

– ODBA: 25 Hz

These specifications are available in the sensor-data-sheets.pdf document, found under the Downloads section on the transmitter product page.

Yes, Thelma Biotel transmitters and receivers are designed to perform reliably in both fresh water and salt water environments. Their robust construction and advanced signal processing ensure strong performance across a wide range of aquatic conditions.

Keep transmitters in the refrigerator when storing to preserve the batterylife as much as possible.

We think it’s important to keep the data in ComPort in it’s original form so that the scientist is always in full control of any changes made to the data. All filtering and adjustment of the data must be done with other tools for analysis, such as R or other software.

Thelma Biotel have made digital receivers for over 10 years. Both the TBR 700 and the TBR 800 family are digital. This has allowed us to make receivers with long batterylife (2 years), large detection storage capacity (up to 3 million detections).

A digital acoustic receiver converts sound energy from transmitters into electrical voltage, analyses the frequency and amplitude through an integrated processor, and stores the results as detections based on established signal protocols. Alternatively, it identifies the signal as background noise if it does not match the established signal protocols.

Digital receiver:

1. Sound energy from the transmitters passes through the transducer in the receiver.

2. This generates an electrical voltage with frequency and amplitude based on the sound signal.

3. The signal is sent to the TBR processor, where mathematical calculations are performed for frequency and amplitude.

4. The result is compared to the signal protocol rules.

5. If it matches, it is stored as transmitter detections; otherwise, it is recorded as background noise.

Regarding the time correction, the TBR 800 uses what is marketed as the world’s most precise clock circuit. It can have clock drift of a maximum of 6,5 seconds per month, but will often be less than this. To be able to correct the clock drift, it’s necessary that the computer used for configuration and download is online and have an internet-adjusted clock. The clock drift in computers will be much greater than in the TBR unit, because the computer can rely on the adjustment through the internet.

If you have provided for configuration and TBR offload from a computer that was online when the operations were performed, then you can use the clock drift that is stated in the ComPort log when connecting the TBR. A linear correction based on the specified clock drift will be sufficient in most cases. A more frequent offload and sync of the TBR clock to a computer with internet access will reduce the drift compared to leaving the receiver in the field for two years without controll of the clock. In two years the clock could drift approximately 2,5 minutes, worst case.

Basic setup:

1. Start two transmitters with magnet and roll them into ducktape (with serial number facing outwards). Attach this to a rope so they won’t fall off during range test.

2. Start up and set out a receiver in a location where it is easily retrieved. Mark the location on your GPS.

3. Move boat to X m away from receiver location, hold the rope with the connected transmitters well under water, wait for transmitter to have transmitted twice. Repeat this step at X and X m away from the receiver.

4. Pick up reiceiver and download data. In ComPort you will be able to view graphs and get an overview of the range in the area.

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When you want to use more than one than one transmitter in the water simultaneously during range testing:

As long as you are looking at the SNR values of the detections, not just the amount of detections coming in, you are good with using more than one transmitter in the water.

If you are only looking at amount of detections, or percentage of transmits detected, and you have several sources of pulse signals in the water at the same time, you will never get 100% of your transmits detected, as some will be lost due to collisions. It is hard to keep track of this as you might have transmitters from other studies or other similar sources of pulse sound in the water while you are doing your range tests. That is also a reason why we propose to use SNR as it is more objective. The level of background noise present when doing the range-tests is also important to include in the presentation of results. If you have high noise, you will have short ranges and low detection success. SNR, signal to noise ratio, while being more objective than detection percentage, is dependent on the background noise. If there is a high background noise, the signal to noise ratio will be lower at the same distance than if the background noise levels where lower. It is just a measure of high high over the noise "carpet" that the signals stand out. Think of signals as flowers standing on a field. If they grass is low (noise) they stand out tall. When the grass is taller, the same height flowers doesn't stand out as tall and are less visible.

Traditionally, and what you mostly find in literature, range tests have been done with VR2 type equipment. Or when done with ours, the figures have been made to match. With VR2 you get no noise levels and no SNR levels, so that is what you have. But a proper range test with more accurate equipment like the TBR, should include SNR and a notion of the average background noise during the tests.

• Transmitters in many sizes, specialized in small sensor technology for acoustic telemetry
• Receievers designed for a variety of study setups and aquatic environments
• Software for data transfer and visualisation of data
• Other services: PinPoint analysis for 2D or 3D positioning

Thelma Biotel develops acoustic transmitters and receivers used to track and monitor fish and other aquatic animals in both freshwater and saltwater. Their products are widely used in research, management, and environmental monitoring worldwide.