- #1
jerin_007
- 7
- 0
Homework Statement
For a mobile receiver operating at a frequency of 900MHz and moving at 100Km/hr.
Homework Equations
Find Doppler frequency.
How Is Doppler Frequency Calculated for a Mobile Receiver?
In summary, the conversation is about finding the Doppler frequency for a mobile receiver operating at 900MHz while moving at 100km/hr. The person asking for help is unsure of which equation to use and is directed to search for information on the Doppler shift or effect. The solution is suggested to be a simple Doppler shift problem with the direction of motion determining whether the phone is redshifting or blueshifting. The equation f1 = f(C1/(C1+Vs)) is recommended for finding the new frequency, with C1 being the speed of sound, f being the original frequency, Vs being the speed of the source, and f1 being the new frequency.
For a mobile receiver operating at a frequency of 900MHz and moving at 100Km/hr.
Find Doppler frequency.
- #2
tiny-tim
Science Advisor
Homework Helper
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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!
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!
- #3
jerin_007
- 7
- 0
Its just a single formula.. I need to know that.
- #4
tiny-tim
Science Advisor
Homework Helper
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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?
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?
- #5
jerin_007
- 7
- 0
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.
- #6
Mark44
Mentor
- 37,770
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You obviously have access to a computer with an internet connection. Search for Doppler shift or Doppler effect, and see what you find.
- #7
phycud
- 1
- 0
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.
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.
- #8
jerin_007
- 7
- 0
Thanks phycud...
FAQ: How Is Doppler Frequency Calculated for a Mobile Receiver?
1. What is Doppler frequency?
Doppler frequency is the change in frequency of a wave due to the relative motion between the source of the wave and the observer. It is named after Austrian physicist Christian Doppler, who first described the phenomenon in 1842.
2. How is Doppler frequency calculated?
Doppler frequency can be calculated using the formula: fD = f0 (v ± vr) / (v ± vs), where fD is the Doppler frequency, f0 is the original frequency, v is the speed of the wave, vr is the relative velocity of the receiver, and vs is the relative velocity of the source.
3. What factors affect Doppler frequency?
The factors that affect Doppler frequency include the speed of the wave, the relative velocities of the source and observer, and the angle at which the wave is approaching the observer.
4. How is Doppler frequency used in real life?
Doppler frequency is used in various applications, including radar systems, medical imaging, and astronomy. In radar systems, it is used to determine the speed and direction of moving objects. In medical imaging, it is used to detect blood flow and diagnose cardiovascular diseases. In astronomy, it is used to study the motion of celestial objects.
5. What is the relationship between Doppler frequency and wavelength?
The relationship between Doppler frequency and wavelength is inverse. This means that as the frequency increases, the wavelength decreases, and vice versa. This is known as the Doppler effect and is observed in various wave phenomena, such as sound waves and electromagnetic waves.
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