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Offline Ncartmell

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  • Poulton-Le-Fylde, Lancashire. UK
Noise Cancelling
« on: July 10, 2017, 12:34:55 PM »
Hello,

I was talking with my friend about the TCB and adding sound, he was not very enthusiastic as he said the motor/gearbox noise almost drowned out the tank sounds.

I then had a thought, why not add noise cancelling to the sound card.

Since the card has not gone for manufacture yet I thought a modification could be done.

My idea,

Add a micro-phone to the board so this can pick up the motor/gearbox noise.

Put a 180° phase shift on the signal (invert).

Amplify the signal and add it the output.

Programming options,

Enable noise cancelling, level adjustment and output with and without tank noise (gives user ability to adjust cancelling without tank sounds).

Regards

Neil

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Offline LukeZ

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Re: Noise Cancelling
« Reply #1 on: July 11, 2017, 04:13:11 PM »
I've been very surprised and impressed at some of the out-of-the-box ideas people have had already. This is a very creative one.

I am not an audio engineer but what little knowledge I have tells me this is not likely to work given various realities and constraints we'd be dealing with, however it would definitely make for an interesting and educational experiment regardless of the outcome.

The board as it exists now could already accommodate a microphone input, all 5 of the RC channels are connected to analog inputs on the Teensy so we could just re-purpose one of those, at least for testing. Then you have to pick a mic (Adafruit, Sparkfun have convenient ones and there is an interesting design over on the Teensy forums), and write a bunch of code.

I will add this to the list of things to explore, I probably won't get far with it myself but it would be a good project for someone who likes to tinker, once (if) these boards become available.

Keep up the creative thinking!
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Offline Ncartmell

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  • Poulton-Le-Fylde, Lancashire. UK
Re: Noise Cancelling
« Reply #2 on: July 12, 2017, 02:28:42 AM »
Hello Luke,
The theory for cancelling is good, however in reality you can only manage about 80%. It takes a finite time to receive the noise, invert, amplify and then send to the speaker so I would guess the best phase shift would be about 190°. This would provide an extremely good reduction in gearbox and motor noise.
Unfortunately I am absolutely useless when it comes to software.
If it proved successful this would, in my estimation, be huge plus point for your sound module as I do not believe anyone provides this feature.

I was going to order ESC and Sound boards, however as I said software is the issue.

Regards

Neil

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Offline johnnyvd

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Re: Noise Cancelling
« Reply #3 on: July 13, 2017, 04:42:00 AM »
You could also look into the following:

  • lower rpm 540 size motors (8500 rpm)
  • decoupling the gear boxes from the chassis
  • soundproofing the gearboxes
  • sound dampening the lower and upper hull etc.

Noise cancellation would be very difficult to obtain because the hull etc. will act as the speaker membrane and noise cancellation itselves only acts through the actual speaker..

Dampening and soundproofing the hull with high inertia material directly to the hull would work (contact noise) especially together with foam filling (air conducted sounds).

Decoupling the gearboxes from the chassis is not wanted most of the time because of the stifness we need for the drive components. This would probably be counter productive..
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