How Is Doppler Frequency Calculated for a Mobile Receiver?

[jerin_007]

Homework Statement

For a mobile receiver operating at a frequency of 900MHz and moving at 100Km/hr.

Homework Equations

Find Doppler frequency.

The Attempt at a Solution

 

[tiny-tim]

Welcome to PF!

Hi jerin_007! Welcome to PF!

Show us what you've tried, and where you're stuck, and then we'll know how to help!

 

[jerin_007]

Its just a single formula.. I need to know that.

 

[tiny-tim]

ok …

then what equations has your professor given you on the subject (or what equations does your book give you)?

and which of those equations do you think will work in this case?

 

[jerin_007]

If that so.. i could have found it.. All i know is how to find doppler spread.. But doppler frequency i can't think of and it isn't there in the book.

 

[Mark44]

You obviously have access to a computer with an internet connection. Search for Doppler shift or Doppler effect, and see what you find.

 

[phycud]

This looks like a simple doppler shift problem:

you should state which direction of motion the moblie phone is in, this determines whether the the phone is redshifting or blueshifting, so that we know what formulas to use.

i'm going to guess you're dropping the mobile phone down something, which means redshifting.

Which should be (correct me if I'm wrong): f1 = f(C1/(C1+Vs))

Where C1 = Speed of sound (343 ms-1)
f = is the original frequency (900hz)
Vs = the speed of the source (mobile phone 100km/hr)
f1 = new frequency

The phone is redshifting therefore the frequency will be less, i'll let you work the rest out.

quite interesting too, i have an exam question similar to this that is very soon.

 

[jerin_007]

Thanks phycud...