Noisy Router Investigation
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Re: Noisy Router Investigation
31-05-2013 11:30 AM
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Product Name: TG582n
Software Release: 8.4.4.I
Software Variant: AJ
Boot Loader Version: 1.0.5
Product Code: 3684778B
Board Name: DANT-T
Re: Noisy Router Investigation
31-05-2013 3:37 PM
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@Razer
What
Edit: to clarify for anyone else reading that wants to add the infomation.
There seems to be a few out there with 8.4.4.i which is a little bit of a mystery at the moment.
Re: Noisy Router Investigation
02-06-2013 3:30 AM
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Re: Noisy Router Investigation
02-06-2013 9:27 AM
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Re: Noisy Router Investigation
03-06-2013 2:30 AM
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Re: Noisy Router Investigation
03-06-2013 9:38 AM
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Re: Noisy Router Investigation
07-06-2013 11:25 AM
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We’ve been pondering the problem of noisy routers for some time trying to get to the bottom of the issue.
We had our supplier place one of our routers in a sound proof chamber and recorded the sound of it running with a wide acoustic range microphone. They found a tone spike at 4kHz which you can see in this plot of frequency vs. amplitude.
Only a handful of people are able to hear this noise without putting the router up to their ear, the noise is only a few dB above background levels so is very hard to hear for the majority of us. For the people that can hear it however it is very annoying!
Further investigation showed that the noise source is a component known as Inductor L14, this component is part of the 1.2V DC circuit. The noise from L14 is due to magnetostriction: the mechanic interaction between the inductor ferrite material and its electrical winding.
The noise has a frequency of 4Khz, if you’d like to hear this noise then watch this https://www.youtube.com/watch?v=lO9uRNrP8Mo video (turn your speakers down!)
We’ve identified a solution which is to introduce a capacitor to remove the 4Khz harmonic without any negative effects (this component is normally present in TG582n devices with the USB port).
The routers with USB ports are not affected because they already contain this extra component which stops this noise, this component is part of the dying gasp circuitry which is not present in the non-USB version. We’ll be making a change in our next manufacturing run which is scheduled for the end of June, these take a while to come from China so will begin shipping to customers later in the year.
If you can hear the noise then let us know, we have some of the quieter routers in the office with this extra component that we can send out.
Thanks,
Matt
Re: Noisy Router Investigation
07-06-2013 11:47 AM
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Re: Noisy Router Investigation
07-06-2013 12:00 PM
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Re: Noisy Router Investigation
07-06-2013 12:15 PM
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Appreciate you letting us all know the outcome.
At that frequency, I guess it's not just down to the age of people who could here it, and found it annoying.
Re: Noisy Router Investigation
07-06-2013 12:41 PM
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I was most intrigued by the "dying gasp circuitry" bit of your explanation.
Now that I understand what it means, I think it begs the question, why would it be missing from newer(?) revisions of the router? Or are these a model for cutting costs, hence stripped down to the bare essentials, which is understandable in the current financial climate?
Anyway, top marks for a top investigation and explanation
[Moderator's note by Dick (Strat) Link
Fixed again - Pedro
Re: Noisy Router Investigation
07-06-2013 1:50 PM
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Re: Noisy Router Investigation
07-06-2013 1:59 PM
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Re: Noisy Router Investigation
07-06-2013 2:09 PM
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Re: Noisy Router Investigation
07-06-2013 9:44 PM
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Anyway, I'm STILL waiting for another bag to return the other two routers I still have.
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