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I'm using a towed array (with two hydrophones and 200m cable) to detect Cetaceans.

We bought from MARINE-ECOSOL. The hydrophone type is Magrec HP03, the DAQ is SAIL DAQ system.

enter image description here

Normally the sounds should be loud, but it was very weak that I need to gain almost 30 dB to hear the sounds. (All sounds, including shipping noise and background noise...etc.)

I used to do research at same time with another towed array which has same hydrophone and cable, althought we used different sound card, the result should be similar. But my towed array still weak more.

When I use headphone to do real-time monitoring, I couldn't hear anything without gain.(can hear a little bit when the hydrophone were very close to the ship)

I think I didn't turn on the preamplifier, but I don't know how to set it in the PAMGuard.

I tried to change the setting in DAQ, but it's still weak when I analyze the wav. file in MATLab. enter image description here

My hydrophones are Magrec HP03, and the array setting is as shown below. enter image description here

I'm newbie in PAMGuard & towed array, and English is not my native language. (I try my best to express questions)

Thank you! I'd appreciate any help.

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  • $\begingroup$ Hello Ruby, welcome to Stack Exchange! Can you edit your question to add more information. (1) You say 'normally sounds are loud'- do you mean normally with this specific towed array/hydrophones? (2) Are you monitoring in real time at sea? Or are you looking at data collected previously? If looking at older data, was it normal loudness when collected? (3) are both channels quiet? (4) what types of hydrophones are you using? (5) is the ship noise the same 'loudness' as 'normal'? Or is it also surprisingly quiet? Can you give more details? Maybe this information will help. $\endgroup$
    – Shannon
    Commented Oct 16, 2023 at 20:32
  • $\begingroup$ Hello, I edit my question and add some information. (1)The shipping noise should be loud when hydrophone close to the ship, but it still weak whenever real-time or check data after. (2) We monitoring in real time at sea. (3) Yes, but one of hydrophone always carry more electric noise. (4) Magrec HP03 (5) All sounds are quiet. $\endgroup$
    – Ruby Wang
    Commented Oct 17, 2023 at 6:46

1 Answer 1

Reset to default
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You have to set the gain in the Magrec HP/27ST (Topeside amplifier filter unit)

In your case set the HP/27ST to a gain of 30 dB.

Caveat: I'm not a Magrec HP03 user but looked up the Web site.

As side note: The preamplifier is typically within the array (to drive the cable) and cannot be changed. However, there is always a programmable gain amplifier (PGA) that can boost the signal before Analog-Digital conversion.

Further, PAMGuard is after Analog-Digital conversion, so it does not change pre-amp and PGA, but it needs these numbers for calibration purpose.

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  • $\begingroup$ I'll try it! Thank you! $\endgroup$
    – Ruby Wang
    Commented Oct 17, 2023 at 9:38
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    $\begingroup$ @RubyWang Did this work? $\endgroup$
    – Shannon
    Commented Oct 18, 2023 at 15:51
  • $\begingroup$ yes, it works. Thank you :) $\endgroup$
    – Ruby Wang
    Commented Oct 30, 2023 at 6:16
  • $\begingroup$ @RubyWang, So you can accept the answer? If so, please do it. $\endgroup$
    – WMXZ
    Commented Oct 30, 2023 at 6:44

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