Author Topic: Dissecting the XM 9 20 MSI T - MEGA xducer ...  (Read 1509 times)

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Offline rnvinc

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Dissecting the XM 9 20 MSI T - MEGA xducer ...
« on: October 14, 2018, 06:09:04 PM »
Interesting stuff  ...





























Rickie
« Last Edit: October 14, 2018, 06:12:41 PM by rnvinc »


Offline Rickard

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Re: Dissecting the XM 9 20 MSI T - MEGA xducer ...
« Reply #1 on: October 23, 2018, 02:19:35 PM »
I agree, interesting! The images contain all data needed for calculating beam forms.  :) This design looks much better than the older models. I dissected several of the old transducers and most of them were defective in some way. For example, all of the sidescan piezos were more or less displaced. This doesn't seem to be a risk with the new XM 9 20 MSI T Mega. I admire the screws... I have wondered how they managed to get 455, 800 and 1200 kHz from the same ducer. The solution is two parallell sidescan arrays, one for 455/800 kHz and a very thin one for 1200 kHz. The piezos are rather short, just 110 mm, but I think this is optimal for short distance scanning at 1200 kHz. At 455/800 kHz the array should be longer, at least 200 mm.

Rickard

Offline rnvinc

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Re: Dissecting the XM 9 20 MSI T - MEGA xducer ...
« Reply #2 on: October 23, 2018, 06:19:47 PM »
I agree, interesting! The images contain all data needed for calculating beam forms.  :) This design looks much better than the older models. I dissected several of the old transducers and most of them were defective in some way. For example, all of the sidescan piezos were more or less displaced. This doesn't seem to be a risk with the new XM 9 20 MSI T Mega. I admire the screws... I have wondered how they managed to get 455, 800 and 1200 kHz from the same ducer. The solution is two parallell sidescan arrays, one for 455/800 kHz and a very thin one for 1200 kHz. The piezos are rather short, just 110 mm, but I think this is optimal for short distance scanning at 1200 kHz. At 455/800 kHz the array should be longer, at least 200 mm.

Rickard

This is great Rickard  ... My goal was hoping you would be willing to draw beam forms from the pictures provided  ...

Please let me know if I can get any other measurements for you  ...
-----

I'm also going to draw up some indications of material softness/hardness used in different areas of the internals of the housings so hopefully you can give insight on why certain materials in certain places inside the housing is used  ...

I will post the image soon  ...

Thanks Rickard  ... You're the best!!

Rickie
« Last Edit: October 23, 2018, 06:27:09 PM by rnvinc »

Offline Whistler

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Re: Dissecting the XM 9 20 MSI T - MEGA xducer ...
« Reply #3 on: October 24, 2018, 06:49:43 AM »
I love you guys.  Keep the gory technical details coming.  I'm eagerly anticipating.

Offline rnvinc

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Re: Dissecting the XM 9 20 MSI T - MEGA xducer ...
« Reply #4 on: October 24, 2018, 07:33:55 AM »


Rickie
« Last Edit: October 24, 2018, 07:37:20 AM by rnvinc »

Offline Rickard

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Re: Dissecting the XM 9 20 MSI T - MEGA xducer ...
« Reply #5 on: October 24, 2018, 12:17:25 PM »
Hi Rickie,
With reference to the numbers in your image:

#1. I think this is sealing between the upper and lower housing parts.
#2. Transducer housing.
#3. Fill that needs to be hard to make the transducer tough.
#4. Lighter fill to avoid making the transducer unnecessarily heavy. I see no other function. The foam cavity may be a disadvantage when using the transducer with a towfish at depth. Foam is compressible and the transducer can change form.
#5. Wires connected to SI and DI piezos and probably shield.
#6. Fixture plus shield for SI and DI piezos.
#7. Sound insulation.
#8. Fill that allows sound to pass.

Rickard
« Last Edit: October 24, 2018, 12:38:59 PM by Rickard »

Offline Whistler

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Re: Dissecting the XM 9 20 MSI T - MEGA xducer ...
« Reply #6 on: October 24, 2018, 12:31:50 PM »
"Rubber type material"...Possibly silicone gasket?

Offline Rickard

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Re: Dissecting the XM 9 20 MSI T - MEGA xducer ...
« Reply #7 on: October 31, 2018, 09:34:21 AM »
I made some calculations on the Mega transducer. They are based on the central frequencies and are most valid for the non-chirp mode. With chirp the spectrum of frequencies is wider, but the results should be about the same.

The horizontal one-way beam width at -3 dB is:
1.48 degrees at 455 kHz.
0.84 degrees at 800 kHz.
0.56 degrees at 1200 kHz.
The vertical beam forms are shown in the figure. At 455 kHz there is no null in the beam. At 800 and 1200 kHz there is a null almost straight beneath the transducer. A null is a sector with weak signal. The result appear as darker areas in the image of the seafloor.
ila_rendered
« Last Edit: October 31, 2018, 05:35:55 PM by Rickard »

Offline Whistler

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Re: Dissecting the XM 9 20 MSI T - MEGA xducer ...
« Reply #8 on: October 31, 2018, 01:38:13 PM »
Very interesting.  And I have witnessed that null, first hand, on my boat.  at which times I was running a Lowarance HDS 12 Gen2 touch at 455KHz while simultaneously running a Helix 12 Mega G2N at 1.2MHz.  That explains the things I could see on the Lowrance and could not see on the Helix.
« Last Edit: November 01, 2018, 12:36:50 PM by Whistler »

Offline rnvinc

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Re: Dissecting the XM 9 20 MSI T - MEGA xducer ...
« Reply #9 on: October 31, 2018, 05:12:31 PM »
Great work Rickard  ... !!

Very cool  ...!!!

Rickie

Offline abraquelebout

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Re: Dissecting the XM 9 20 MSI T - MEGA xducer ...
« Reply #10 on: November 04, 2018, 02:59:45 AM »
It's interesting, as any one know the wiring of this ducer ?
I test a 100 m extension câble, good result. there'is 10 wire...if whe do 2 wire for an élement 2 left, 2 right for all piezzo  and 2 for T°....the ground sem's not comun except for 200 and T°

Offline rnvinc

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Re: Dissecting the XM 9 20 MSI T - MEGA xducer ...
« Reply #11 on: November 04, 2018, 06:05:05 AM »
It's interesting, as any one know the wiring of this ducer ?
I test a 100 m extension câble, good result. there'is 10 wire...if whe do 2 wire for an élement 2 left, 2 right for all piezzo  and 2 for T°....the ground sem's not comun except for 200 and T°

I can get the wire color code and pinout for the XM 9 20 MSI T (which is the HELIX MEGA xducer I dissected in this thread)  ...

Your question seems to inquire about the XM 14 20 MSI T  ...??

Rickie
« Last Edit: November 04, 2018, 06:07:34 AM by rnvinc »

Offline abraquelebout

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Re: Dissecting the XM 9 20 MSI T - MEGA xducer ...
« Reply #12 on: November 04, 2018, 07:48:19 AM »
Yes it's this ducer, i make 8 wire extension, it work but i wonder fore colours of wire
if you can read them it's cool
thanks

Offline rnvinc

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Re: Dissecting the XM 9 20 MSI T - MEGA xducer ...
« Reply #13 on: November 06, 2018, 01:30:18 AM »


Rickie

Offline abraquelebout

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Re: Dissecting the XM 9 20 MSI T - MEGA xducer ...
« Reply #14 on: November 06, 2018, 10:08:42 AM »
Nice and thank's
if i understand, they make a comun ground as they done for ancient system.
there is only two wire for array, one + and -
if whe chose 1275 khz, all the arrays received this, the 1,6 and 3,8 mm piezzo ?

Offline sfw1960

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Re: Dissecting the XM 9 20 MSI T - MEGA xducer ...
« Reply #15 on: November 10, 2018, 09:06:44 PM »
Because of fancy terms like inductive reactance, capacitive reactance and resistance - a resonant circuit acts as a magnet to certain things it is designed for - in short two peizo elements can be hooked to the same wires, but the one that is closely tuned to the resonant frequency  has more "attraction" and  "pulls" the energy into it's path of least resistance, so the Mega SI frequency will "feed" into the 1.6MM elements with ease and it doesn't even "see" the element that isn't tuned to pickup on that "path" near as easily....

Hope that makes sense - as explaining technology isn't always the easiest thing to do unless you're familiar with the terminology or theory.

HTH~
Robert

Offline abraquelebout

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Re: Dissecting the XM 9 20 MSI T - MEGA xducer ...
« Reply #16 on: November 11, 2018, 03:23:41 AM »
sure, i'm not in my élément with this subject but i learn
thank's 8)


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