<p>As stated above, two separate Soundtrap 4300 units had incomplete signals. One had little to no signal only on channel 1 and the other on channel 1 &amp; 2.</p>
<p>After bench testing with other hydrophone arrays it was confirmed that this was a hardware issue with the recorder itself and could only be resolved by sending it in to Ocean Instruments for repair. After repair, the instruments are working as expected.</p>

CC BY-SA 4.0
2024-08-12T20:20:55.537Z
2024-08-12T20:20:55.537Z
Kourtney Burger
<p>A quick answer concerning decimation:</p>
<p>according to matlab : &quot;Decimation factor, specified as a positive integer. For better results when r is greater than 13, divide r into smaller factors and call decimate several times.&quot;</p>
<p>So, I would suggest to try to decimate 4 times each decimation by a factor of 8, to see if result improves.</p>
<p>Reason, why high decimation factors are problematic is the required anti-aliasing filter: in the case of OP, the LP cutoff frequency is 1/32 = 0.031, which is very low and may result into a weird filters responses, as Triton does not specify a filter order.</p>

CC BY-SA 4.0
2023-06-10T14:33:29.967Z
2023-06-10T14:52:20.630Z
2023-06-10T14:52:20.630Z
WMXZ
<p>We have collected 2 channeled recordings from two different ST4300 units, and more recently we have noticed that the signal in CH1 looks really weak. This has occurred in most but not all new deployments. We know the signal is there because if we make an LTSA from the recordings we can see dolphins and ship noise, albeit very faint. What we don’t understand is that when we decimate the recordings to 12kHz from 384kHz we get a very odd banding pattern in the signal. It almost looks like the signal is cutting in and out.</p>
<p><strong>Has anyone experienced this faint signal and banding before with a SoundTrap 4300 model? We aren’t sure why this is happening.</strong></p>
<p><a href="https://i.sstatic.net/6bZI1.png" rel="noreferrer"><img src="https://i.sstatic.net/6bZI1.png" alt="Both channel waveforms and spectrogram, showing faint signal on CH1" /></a>
<em><strong>Both channel waveforms and spectrograms, showing faint signal on CH1</strong></em></p>
<p><a href="https://i.sstatic.net/hvnWU.png" rel="noreferrer"><img src="https://i.sstatic.net/hvnWU.png" alt="enter image description here" /></a>
<em><strong>Banding in 12kHz decimated wav files</strong></em></p>

CC BY-SA 4.0
2023-06-08T18:29:48.653Z
Can you tell us, how you decimate?
WMXZ
CC BY-SA 4.0
2023-06-08T19:28:27.873Z
We decimated using the Triton package in MATLAB
Kourtney Burger
CC BY-SA 4.0
2023-06-09T05:29:31.563Z
Sorry, but which  function call, how many steps, what decimation factors? It is difficult with the given information to help.
WMXZ
CC BY-SA 4.0
2023-06-09T19:56:13.040Z
@WMXZ the lab uses SIO's Triton 2020 to decimate using the "decimate all wav files in a folder" option from the menu drop down. We decimate by a factor of 32. We don't get to chose the step size as it is built into the code from what I believe. We have used this function on over 50 deployments with out a prior issue so I don't think it is related to the software?
Cory Hom-Weaver
CC BY-SA 4.0
2023-11-20T10:31:40.430Z
This looks like a weak connection to me. Have you tested this on shore with different hydrophones in different ports? I feel like your decimation is weird because your signal isn't complete for its sample rate.
etgriffiths
<recording><soundtrap><hydrophone><equipment><hardware>
SoundTrap 4300 CH1 Faint Signal & Banding
# SoundTrap 4300 CH1 Faint Signal & Banding

(Asked by: username_0 on 2023-06-08)

We have collected 2 channeled recordings from two different ST4300 units, and more recently we have noticed that the signal in CH1 looks really weak. This has occurred in most but not all new deployments. We know the signal is there because if we make an LTSA from the recordings we can see dolphins and ship noise, albeit very faint. What we don’t understand is that when we decimate the recordings to 12kHz from 384kHz we get a very odd banding pattern in the signal. It almost looks like the signal is cutting in and out.

**Has anyone experienced this faint signal and banding before with a SoundTrap 4300 model? We aren’t sure why this is happening.**

[![Both channel waveforms and spectrogram, showing faint signal on CH1](https://i.sstatic.net/6bZI1.png)](https://i.sstatic.net/6bZI1.png)
***Both channel waveforms and spectrograms, showing faint signal on CH1***

[![enter image description here](https://i.sstatic.net/hvnWU.png)](https://i.sstatic.net/hvnWU.png)
***Banding in 12kHz decimated wav files***

**Tags:** recording, soundtrap, hydrophone, equipment, hardware

> **Comments:**
> **username_1**: Can you tell us, how you decimate?  
> **username_0**: We decimated using the Triton package in MATLAB  
> **username_1**: Sorry, but which  function call, how many steps, what decimation factors? It is difficult with the given information to help.  
> **username_2**: @username_1 the lab uses SIO's Triton 2020 to decimate using the "decimate all wav files in a folder" option from the menu drop down. We decimate by a factor of 32. We don't get to chose the step size as it is built into the code from what I believe. We have used this function on over 50 deployments with out a prior issue so I don't think it is related to the software?  
> **username_3**: This looks like a weak connection to me. Have you tested this on shore with different hydrophones in different ports? I feel like your decimation is weird because your signal isn't complete for its sample rate.  

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## 2 answers

### Answer by username_0 on 2024-08-12. Score: 1 | Accepted answer

As stated above, two separate Soundtrap 4300 units had incomplete signals. One had little to no signal only on channel 1 and the other on channel 1 & 2.

After bench testing with other hydrophone arrays it was confirmed that this was a hardware issue with the recorder itself and could only be resolved by sending it in to Ocean Instruments for repair. After repair, the instruments are working as expected.


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### Answer by username_1 on 2023-06-10. Score: 0

A quick answer concerning decimation:

according to matlab : "Decimation factor, specified as a positive integer. For better results when r is greater than 13, divide r into smaller factors and call decimate several times."

So, I would suggest to try to decimate 4 times each decimation by a factor of 8, to see if result improves.

Reason, why high decimation factors are problematic is the required anti-aliasing filter: in the case of OP, the LP cutoff frequency is 1/32 = 0.031, which is very low and may result into a weird filters responses, as Triton does not specify a filter order.


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