Reply by John O'Flaherty●January 11, 20092009-01-11
On Sun, 11 Jan 2009 10:41:35 -0600, Frnak McKenney
<frnak@far.from.the.madding.crowd.com> wrote:
>On Sat, 10 Jan 2009 16:26:27 -0600, John O'Flaherty <quiasmox@yeeha.com> wrote:
>> On Fri, 09 Jan 2009 19:24:36 -0700, Eric Jacobsen
>><eric.jacobsen@ieee.org> wrote:
>>>On Fri, 9 Jan 2009 10:28:44 -0800 (PST), Le Chaud Lapin
>>><jaibuduvin@gmail.com> wrote:
>>>>On Jan 9, 12:03�pm, Eric Jacobsen <eric.jacob...@ieee.org> wrote:
>>>>> On Fri, 09 Jan 2009 11:44:03 -0600, "briang2000"
>>>>> >We've got a safety-related application where we'd like to determine if a
>>>>> >shower is running in the bathroom. �Does anyone have any suggestions on how
>>>>> >that determination could be made by sound?
>--snip--
>>>My concern with a DSP approach
>>>would be false alarms from other
>>>"noisy" things like hairdryers, bath fans, shavers, electric
>>>toothbrush, etc., etc. Discriminating one type of "noise" from
>>>another reliably can be pretty tricky.
>>
>> Combining a flow sensor and acoustical approach, a piezo sensor
>> attached to the pipe feeding the shower head would give a better SNR,
>> and still wouldn't be mechanical or require re-plumbing. I just tried
>> an automotive mechanic's stethoscope on a kitchen water pipe, and it
>> gives quite a loud hissing when the water is running, and not much
>> other sound.
>> The spectrum would shift some with water temperature and flow rate,
>> but it's a really strong signal.
>> If you could make it low-power enough to work from a lithium battery,
>> and using a wireless scheme, it wouldn't require any wiring inside the
>> shower stall.
>
>I do have one concern with a directly-connected audio transducer.
>Ever tapped on a radiator pipe? I know that both water and (metal)
>pipes are excellent conductors of sound; how much of a problem will
>a house with two showers present?
>
>That is, how much of the sound from S1 running will be picked up by
>the transducer attached to S2? This is one case where an "air pickup"
>might be better than mechanical coupling.
>
>Anyone have any relevant experience?
I just acquired some by experiment. I used the mechanical stethoscope
I mentioned, and found that I couldn't hear any sound in the shower
pipe when running nearby taps or the toilet, which come from the same
source pipe. When listening to the shower pipe with the diverter valve
feeding the water away from the shower, the sound was audible, but
still much weaker than when the water was coming out of the shower
pipe.
The stethoscope is so constructed that it senses radial movement of
the pipe wall. You can hear a poorer version of the sound with a
screwdriver, with the handle end pressed into your ear, and the tip to
the pipe.
Why does the sound attenuate so much though there's a water/metal
path? Maybe it's weakened by dispersion, especially at higher
frequencies. Also, there isn't a continuous water path if the shower
is in fact turned off, and the speed of sound in copper is about three
times faster than in water, increasing dispersion. Finally, maybe the
sound propagated over distance through the pipe isn't such as to make
the pipe wall vibrate radially at higher frequencies.
--
John
Reply by Frnak McKenney●January 11, 20092009-01-11
On Sat, 10 Jan 2009 16:26:27 -0600, John O'Flaherty <quiasmox@yeeha.com> wrote:
> On Fri, 09 Jan 2009 19:24:36 -0700, Eric Jacobsen
><eric.jacobsen@ieee.org> wrote:
>>On Fri, 9 Jan 2009 10:28:44 -0800 (PST), Le Chaud Lapin
>><jaibuduvin@gmail.com> wrote:
>>>On Jan 9, 12:03�pm, Eric Jacobsen <eric.jacob...@ieee.org> wrote:
>>>> On Fri, 09 Jan 2009 11:44:03 -0600, "briang2000"
>>>> >We've got a safety-related application where we'd like to determine if a
>>>> >shower is running in the bathroom. �Does anyone have any suggestions on how
>>>> >that determination could be made by sound?
--snip--
>>My concern with a DSP approach
>>would be false alarms from other
>>"noisy" things like hairdryers, bath fans, shavers, electric
>>toothbrush, etc., etc. Discriminating one type of "noise" from
>>another reliably can be pretty tricky.
>
> Combining a flow sensor and acoustical approach, a piezo sensor
> attached to the pipe feeding the shower head would give a better SNR,
> and still wouldn't be mechanical or require re-plumbing. I just tried
> an automotive mechanic's stethoscope on a kitchen water pipe, and it
> gives quite a loud hissing when the water is running, and not much
> other sound.
> The spectrum would shift some with water temperature and flow rate,
> but it's a really strong signal.
> If you could make it low-power enough to work from a lithium battery,
> and using a wireless scheme, it wouldn't require any wiring inside the
> shower stall.
I do have one concern with a directly-connected audio transducer.
Ever tapped on a radiator pipe? I know that both water and (metal)
pipes are excellent conductors of sound; how much of a problem will
a house with two showers present?
That is, how much of the sound from S1 running will be picked up by
the transducer attached to S2? This is one case where an "air pickup"
might be better than mechanical coupling.
Anyone have any relevant experience?
Frank McKenney
--
�The most exciting phrase to hear in science, the one that
heralds new discoveries, is not �Eureka!� (I found it!)
but �"That's funny..."� -- Isaac Asimov
--
Frank McKenney, McKenney Associates
Richmond, Virginia / (804) 320-4887
Munged E-mail: frank uscore mckenney ayut mined spring dawt cahm (y'all)
Reply by John O'Flaherty●January 10, 20092009-01-10
On Fri, 09 Jan 2009 19:24:36 -0700, Eric Jacobsen
<eric.jacobsen@ieee.org> wrote:
>On Fri, 9 Jan 2009 10:28:44 -0800 (PST), Le Chaud Lapin
><jaibuduvin@gmail.com> wrote:
>
>>On Jan 9, 12:03�pm, Eric Jacobsen <eric.jacob...@ieee.org> wrote:
>>> On Fri, 09 Jan 2009 11:44:03 -0600, "briang2000"
>>> >We've got a safety-related application where we'd like to determine if a
>>> >shower is running in the bathroom. �Does anyone have any suggestions on how
>>> >that determination could be made by sound? � Might a shower have a specific
>>> >white noise characteristic that could be identified as unique from music
>>> >playing, toilet flushing, talking, etc.?
>>>
>>> Is there a reason this has to be done via audio processing? � �A flow
>>> meter on the head or even just a water detector at the floor might be
>>> more reliable.
>>
>>Interesting application.
>>
>>Audio might be more convenient. One can imagine using a wall-wart with
>>integrated Wi-Fi transceiver that sends an alarm over Internet when
>>shower is running. Might even have small, directional camera built-
>>in. ;)
>>
>>This is certainly feasible. At a given flow rate, the white noise will
>>likely be stationary, and will have certain characteristics, among
>>them being power spectral density, using which you can apply several
>>techniques (matched filter/MMSE/etc).
>>
>>I would be surprised if you did not have almost immediate success
>>since the NNR ("noise"-to-noise) ratio is large. You might build-in
>>self-training feauture so that module determines empirically what
>>"shower on" is versus "shower off" with push of button on module.
>>
>>Typical 16MHz DSP should be more than enough since application is
>>pseudo-real-time.
>>
>>-Le Chaud Lapin-
>
>My concern with a DSP approach would be false alarms from other
>"noisy" things like hairdryers, bath fans, shavers, electric
>toothbrush, etc., etc. Discriminating one type of "noise" from
>another reliably can be pretty tricky.
Combining a flow sensor and acoustical approach, a piezo sensor
attached to the pipe feeding the shower head would give a better SNR,
and still wouldn't be mechanical or require re-plumbing. I just tried
an automotive mechanic's stethoscope on a kitchen water pipe, and it
gives quite a loud hissing when the water is running, and not much
other sound.
The spectrum would shift some with water temperature and flow rate,
but it's a really strong signal.
If you could make it low-power enough to work from a lithium battery,
and using a wireless scheme, it wouldn't require any wiring inside the
shower stall.
--
John
Reply by Jerry Avins●January 10, 20092009-01-10
kennheinrich@sympatico.ca wrote:
> On Jan 10, 11:58 am, Randy Yates <ya...@ieee.org> wrote:
>> dbd <d...@ieee.org> writes:
>>> On Jan 10, 6:12 am, kennheinr...@sympatico.ca wrote:
>>>> ...
>>>>>>> On Fri, 09 Jan 2009 11:44:03 -0600, "briang2000"
>>>>>>>> We've got a safety-related application where we'd like to determine if a
>>>>>>>> shower is running in the bathroom. Does anyone have any suggestions on how
>>>>>>>> that determination could be made by sound? Might a shower have a specific
>>>>>>>> white noise characteristic that could be identified as unique from music
>>>>>>>> playing, toilet flushing, talking, etc.?
>>> .>
>>> .> While most of the readers of this group will immediately start
>>> .> thinking acoustics, spectral properties and bandwidths, I like the
>>> .> simple approaches like flow meters.
>>> .> ...
>>> .> - Kenn
>>> In this thread, the OP has asked for an acoustic implementation of a
>>> solution. The OP hasn't shared with us what the problem is, yet. Of
>>> course, that makes it impossible to tell if any particular
>>> implementation would actually be a solution.
>> Amen, brother!
>>
>> I know that, many times, a poster had a poor system design in mind and
>> thus there was an easier/more efficient/more elegant way to skin the
>> cat. However, in my opinion, there is too much second-guessing that
>> occurs immediately in which people here assume the poster is an
>> idiot.
>>
>> There is a world of difference between "a flow meter would be better"
>> versus "have you considered a completely different approach such as a
>> flow meter" - one assumes the poster is an idiot and one does not.
>> --
>> % Randy Yates % "Midnight, on the water...
>> %% Fuquay-Varina, NC % I saw... the ocean's daughter."
>> %%% 919-577-9882 % 'Can't Get It Out Of My Head'
>> %%%% <ya...@ieee.org> % *El Dorado*, Electric Light Orchestrahttp://www.digitalsignallabs.com
>
> Good point. I clearly missed the OP's stated requirement in the first
> post. But I know I've been guilty of allowing myself to be seduced by
> a "neat" or fancy theoretical solution to a problem, and spending way
> too much time and effort making it work, and then realizing I should
> have just done the obvious :-) The trick, I suppose, is to realize
> those times when the obvious solution is the wrong one!
Like rotary position encoders on the valve handles?
Jerry
--
Engineering is the art of making what you want from things you can get.
�����������������������������������������������������������������������
Reply by ●January 10, 20092009-01-10
On Jan 10, 11:58�am, Randy Yates <ya...@ieee.org> wrote:
> dbd <d...@ieee.org> writes:
> > On Jan 10, 6:12 am, kennheinr...@sympatico.ca wrote:
> >>...
>
> >> > >> On Fri, 09 Jan 2009 11:44:03 -0600, "briang2000"
> >> > >> >We've got a safety-related application where we'd like to determine if a
> >> > >> >shower is running in the bathroom. �Does anyone have any suggestions on how
> >> > >> >that determination could be made by sound? � Might a shower have a specific
> >> > >> >white noise characteristic that could be identified as unique from music
> >> > >> >playing, toilet flushing, talking, etc.?
>
> > .>
> > .> While most of the readers of this group will immediately start
> > .> thinking acoustics, spectral properties and bandwidths, I like the
> > .> simple approaches like flow meters.
> > .> ...
> > .> �- Kenn
>
> > In this thread, the OP has asked for an acoustic implementation of a
> > solution. The OP hasn't shared with us what the problem is, yet. Of
> > course, that makes it impossible to tell if any particular
> > implementation would actually be a solution.
>
> Amen, brother!
>
> I know that, many times, a poster had a poor system design in mind and
> thus there was an easier/more efficient/more elegant way to skin the
> cat. However, in my opinion, there is too much second-guessing that
> occurs immediately in which people here assume the poster is an
> idiot.
>
> There is a world of difference between "a flow meter would be better"
> versus "have you considered a completely different approach such as a
> flow meter" - one assumes the poster is an idiot and one does not.
> --
> % �Randy Yates � � � � � � � � �% "Midnight, on the water...
> %% Fuquay-Varina, NC � � � � � �% �I saw... �the ocean's daughter."
> %%% 919-577-9882 � � � � � � � �% 'Can't Get It Out Of My Head'
> %%%% <ya...@ieee.org> � � � � � % *El Dorado*, Electric Light Orchestrahttp://www.digitalsignallabs.com
Good point. I clearly missed the OP's stated requirement in the first
post. But I know I've been guilty of allowing myself to be seduced by
a "neat" or fancy theoretical solution to a problem, and spending way
too much time and effort making it work, and then realizing I should
have just done the obvious :-) The trick, I suppose, is to realize
those times when the obvious solution is the wrong one!
- Kenn
Reply by ●January 10, 20092009-01-10
X-no-archive:
On Jan 10, 12:36�pm, Le Chaud Lapin <jaibudu...@gmail.com> wrote:
> On Jan 10, 10:58�am, Randy Yates <ya...@ieee.org> wrote:
>
> > Amen, brother!
>
> > I know that, many times, a poster had a poor system design in mind and
> > thus there was an easier/more efficient/more elegant way to skin the
> > cat. However, in my opinion, there is too much second-guessing that
> > occurs immediately in which people here assume the poster is an
> > idiot.
>
> > There is a world of difference between "a flow meter would be better"
> > versus "have you considered a completely different approach such as a
> > flow meter" - one assumes the poster is an idiot and one does not.
>
> Also, on the matter of simplicity, I would find it far easier to make
> a reliable wall-warted electronic device than a pipe-mounted electro-
> mechanical device.
>
> Right now, my toilet is making a funny noise constantly. I tried to
> fix it, and only made it worse.
>
> -Le Chaud Lapin-
you know, interesting you should mention that...for a simple looking
device, the workings in a toilet tank are really rather complex...
relying on the second order system nature of water flow... you know
the flapper valve is a bimodal device with hysteresis.. man Joe the
plumber should get more respect..
Mark
Reply by Le Chaud Lapin●January 10, 20092009-01-10
On Jan 10, 10:58�am, Randy Yates <ya...@ieee.org> wrote:
> Amen, brother!
>
> I know that, many times, a poster had a poor system design in mind and
> thus there was an easier/more efficient/more elegant way to skin the
> cat. However, in my opinion, there is too much second-guessing that
> occurs immediately in which people here assume the poster is an
> idiot.
>
> There is a world of difference between "a flow meter would be better"
> versus "have you considered a completely different approach such as a
> flow meter" - one assumes the poster is an idiot and one does not.
Also, on the matter of simplicity, I would find it far easier to make
a reliable wall-warted electronic device than a pipe-mounted electro-
mechanical device.
Right now, my toilet is making a funny noise constantly. I tried to
fix it, and only made it worse.
-Le Chaud Lapin-
Reply by Randy Yates●January 10, 20092009-01-10
dbd <dbd@ieee.org> writes:
> On Jan 10, 6:12 am, kennheinr...@sympatico.ca wrote:
>>...
>
>> > >> On Fri, 09 Jan 2009 11:44:03 -0600, "briang2000"
>> > >> >We've got a safety-related application where we'd like to determine if a
>> > >> >shower is running in the bathroom. Does anyone have any suggestions on how
>> > >> >that determination could be made by sound? Might a shower have a specific
>> > >> >white noise characteristic that could be identified as unique from music
>> > >> >playing, toilet flushing, talking, etc.?
>
> .>
> .> While most of the readers of this group will immediately start
> .> thinking acoustics, spectral properties and bandwidths, I like the
> .> simple approaches like flow meters.
> .> ...
> .> - Kenn
>
> In this thread, the OP has asked for an acoustic implementation of a
> solution. The OP hasn't shared with us what the problem is, yet. Of
> course, that makes it impossible to tell if any particular
> implementation would actually be a solution.
Amen, brother!
I know that, many times, a poster had a poor system design in mind and
thus there was an easier/more efficient/more elegant way to skin the
cat. However, in my opinion, there is too much second-guessing that
occurs immediately in which people here assume the poster is an
idiot.
There is a world of difference between "a flow meter would be better"
versus "have you considered a completely different approach such as a
flow meter" - one assumes the poster is an idiot and one does not.
--
% Randy Yates % "Midnight, on the water...
%% Fuquay-Varina, NC % I saw... the ocean's daughter."
%%% 919-577-9882 % 'Can't Get It Out Of My Head'
%%%% <yates@ieee.org> % *El Dorado*, Electric Light Orchestra
http://www.digitalsignallabs.com
Reply by dbd●January 10, 20092009-01-10
On Jan 10, 6:12 am, kennheinr...@sympatico.ca wrote:
>...
> > >> On Fri, 09 Jan 2009 11:44:03 -0600, "briang2000"
> > >> >We've got a safety-related application where we'd like to determine if a
> > >> >shower is running in the bathroom. Does anyone have any suggestions on how
> > >> >that determination could be made by sound? Might a shower have a specific
> > >> >white noise characteristic that could be identified as unique from music
> > >> >playing, toilet flushing, talking, etc.?
.>
.> While most of the readers of this group will immediately start
.> thinking acoustics, spectral properties and bandwidths, I like the
.> simple approaches like flow meters.
.> ...
.> - Kenn
In this thread, the OP has asked for an acoustic implementation of a
solution. The OP hasn't shared with us what the problem is, yet. Of
course, that makes it impossible to tell if any particular
implementation would actually be a solution.
Dale B. Dalrymple
Reply by John●January 10, 20092009-01-10
On Jan 10, 9:12�am, kennheinr...@sympatico.ca wrote:
> On Jan 9, 9:24�pm, Eric Jacobsen <eric.jacob...@ieee.org> wrote:
>
>
>
> > On Fri, 9 Jan 2009 10:28:44 -0800 (PST), Le Chaud Lapin
>
> > <jaibudu...@gmail.com> wrote:
> > >On Jan 9, 12:03�pm, Eric Jacobsen <eric.jacob...@ieee.org> wrote:
> > >> On Fri, 09 Jan 2009 11:44:03 -0600, "briang2000"
> > >> >We've got a safety-related application where we'd like to determine if a
> > >> >shower is running in the bathroom. �Does anyone have any suggestions on how
> > >> >that determination could be made by sound? � Might a shower have a specific
> > >> >white noise characteristic that could be identified as unique from music
> > >> >playing, toilet flushing, talking, etc.?
>
> > >> Is there a reason this has to be done via audio processing? � �A flow
> > >> meter on the head or even just a water detector at the floor might be
> > >> more reliable.
>
> > >Interesting application.
>
> > >Audio might be more convenient. One can imagine using a wall-wart with
> > >integrated Wi-Fi transceiver that sends an alarm over Internet when
> > >shower is running. �Might even have small, directional camera built-
> > >in. ;)
>
> > >This is certainly feasible. At a given flow rate, the white noise will
> > >likely be stationary, and will have certain characteristics, among
> > >them being power spectral density, using which you can apply several
> > >techniques (matched filter/MMSE/etc).
>
> > >I would be surprised if you did not have almost immediate success
> > >since the NNR ("noise"-to-noise) ratio is large. You might build-in
> > >self-training feauture so that module determines empirically what
> > >"shower on" is versus "shower off" with push of button on module.
>
> > >Typical 16MHz DSP should be more than enough since application is
> > >pseudo-real-time.
>
> > >-Le Chaud Lapin-
>
> > My concern with a DSP approach would be false alarms from other
> > "noisy" things like hairdryers, bath fans, shavers, electric
> > toothbrush, etc., etc. � Discriminating one type of "noise" from
> > another reliably can be pretty tricky.
>
> > Eric Jacobsen
> > Minister of Algorithms
> > Abineau Communicationshttp://www.ericjacobsen.org
>
> > Blog:http://www.dsprelated.com/blogs-1/hf/Eric_Jacobsen.php
>
> While most of the readers of this group will immediately start
> thinking acoustics, spectral properties and bandwidths, I like the
> simple approaches like flow meters. �In my own house, the shower is
> the loudest appliance - what about a simple noise power threshold
> detector? If this is a custom install in a known environment this
> might be sufficient.
>
> Is this safety in the sense of electrical current? In that case, you
> would also need to detect trickles of water, which means the noise and
> spectrum changes considerably and actual, physical, liquid water
> sensors make more sense. Is this to detect if someone passes out in
> the shower and then if the shower runs for 20 minutes an alarm goes?
> In that case your loudness might be OK but still doesn't address the
> problem (someone passed out when the shower was off).
>
> �- Kenn
Temperature sensor on the pipe to the showerhead?
John