**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">

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

--e89a8ff1ce26074ece04ba1ec996--

From tap-l-owner@lists.ncsu.edu Wed Feb 29 14:13:42 2012

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