Date: Wed, 29 Feb 2012 13:48:11

Author: --- Thomas J Bauer

Subject: Re: How to Measure Doppler Shift

Post:

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Jerry,

I do the doppler shift by recording a sound file .wav and do a Fourier
Transform on it.
The problem with trying to do it with an oscilloscope is the size of the
shift. If I can measure a difference of 0.1 div
on a 10.0 division scale that represents 1/100 (330 m/s) = 3 m/s.
So you need something moving fairly fast to easily measure it.
The frequency shift of a whistle spinning around in a circle is hard to
see.

Here is a link to the sonogram file I use in Matlab. It also has a
recording of a campus
police car traveling 57 MPH in a 45 while playing a 1kHz CD through his PA.
You could try down loading the sound file and use a microphone
and a digital oscilloscope to try and measure the shift

http://www.wellesley.edu/Physics/Tbauer/Car/

If you don't have Matlab and are interested in it. I could try making a
stand alone executable. I can't tell if it will work, because it needs a
runtime module
that won't work on a computer that has Matlab on it. All the computers I
have acces to have Matlab installed on them.

Tom
--
Tom Bauer
Sr Instructor Physics Laboratory
Wellesley College
Wellesley, MA 02481

On Wed, Feb 29, 2012 at 12:48 PM, Zani, Gerald wrote:

> Tapplers,
>
> How do you measure the Doppler shift on the oscilloscope?
>
> Does anyone do it with a beat between two identical sources, one
> stationary and one moving?
>
>
> Thanks,
> - Jerry
>
> --
> Gerald Zani
> Demonstration Manager
> Physics
> Brown University
> (401) 863-3964
>
>

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Content-Type: text/html; charset=ISO-8859-1
Content-Transfer-Encoding: quoted-printable

Jerry,
=A0
I do the doppler shift by recording a sound file .wav and do a Fourier=
Transform on it.
The problem with trying to do it with an oscilloscope is the size of t=
he shift. If I can measure a difference of 0.1 div
on a 10.0 division scale that represents 1/100 (330 m/s) =3D 3 m/s.
So you need something moving fairly fast to easily measure it.
The frequency shift of=A0a whistle spinning around in a circle is hard=
to see.
=A0
Here is a link to the sonogram file I use in Matlab. It also has a rec=
ording of a campus
police car traveling 57 MPH in a 45 while playing a 1kHz CD through hi=
s PA. You could try down loading the sound file and use a microphone=A0
and a digital oscilloscope to try and measure the shift
=A0
http://www.we=
llesley.edu/Physics/Tbauer/Car/
=A0
If you don't have Matlab and are interested in it.=A0I could try m=
aking a stand alone executable. I can't tell if it will work, because i=
t needs a runtime module
that won't work on a computer that has Matlab on it. All the compu=
ters I have acces to have Matlab installed on them.
=A0
Tom=A0
-- Tom BauerSr Instructor Physics LaboratoryWellesley Coll=
egeWellesley, MA 02481
On Wed, Feb 29, 2012 at 12:48 PM, Zani, Gerald <=
span dir=3D"ltr"> rown.edu> wrote:
Tapplers,How do you measure t=
he Doppler shift on the oscilloscope?Does anyone do it with a beat =
between two identical sources, one stationary and one moving?
Thanks,- Jerry-- =
Gerald ZaniDemonstration ManagerPhysicsBrown University=
(401) 863-3964


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