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The Doppler Effect......
#11
RE: The Doppler Effect......
(May 4, 2021 at 8:47 am)onlinebiker Wrote: No.

Doppler effect is obsevable only from an observer' s point of view.

That is - the audio frequency of the moving object (like a train coming towards you) in reality is constant - but APPEARS to the observer as ascending in frequency.


The same can be observed by a moving observer and a stationary source of sound.


Trust me - I KNOW Doppler effect.

I was taught it back in 1981 when I was a Coast Guard Radioman - and SARSAT went on line. SARSAT uses Doppler shift - observing an EPIRB on the ground and by measuring the intensity of the doppler shift can calculate two possible positions of the EPIRB transmitter on either side of the satellite' s polar track....

You are correct, but so am I.  I never said anything that contradicts your explanation.  Frequency is dependent on observer.  The source frequency remains constant, but frequency of detection depends on the relative speeds of the source and observer, and its relation to the speed of sound.

Trust me - I KNOW Doppler effect.

I am a physicist.
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#12
RE: The Doppler Effect......
Go back and read what you wrote.


You said the frequency IS.

not the frequency APPEARS to the observer to change.

See the problem?
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#13
RE: The Doppler Effect......
(May 4, 2021 at 8:51 am)The Grand Nudger Wrote: Without making your head explode - imagine an ambulance is emitting a wave.  The wave itself is uniform in all directions.  The ambulance, however, is moving toward you - and so the point of emanation for the wave is piling up on itself, making the waves ahead tighter, and making the waves behind looser.

Just like if I walked toward you making waves in a pool.  If I push a ball down into the water every second while stationary, you'll see the uniform wave.  If I push the ball down every second while moving forward a foot every second, you'll see the leading edge pile up and the trailing edge spread out.

I think I got it. It really is about proximity. The closer the wave gets to something, the more jammed up it becomes. Correct me if I am wrong, but would it be wrong to equate that to a ocean wave building up and gettign bigger closer to the shore?
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#14
RE: The Doppler Effect......
(May 4, 2021 at 8:47 am)onlinebiker Wrote:
(May 3, 2021 at 5:40 pm)HappySkeptic Wrote: When a sound source is moving toward you, its frequency or pitch is higher (think soprano instead of bass).

When a sound source is moving away from you, its frequency (or pitch) is lower.

You also get a higher volume when a sound source is close to you.  If someone hits a bell right in front of you, its louder than if it is down the street.

The two effects together explain the sound of a fire engine coming toward you and going away.

No.

Doppler effect is obsevable only from an observer' s point of view.

That is - the audio frequency of the moving object (like a train coming towards you) in reality is constant - but APPEARS to the observer as ascending in frequency.


The same can be observed by a moving observer and a stationary source of sound.


Trust me - I KNOW Doppler effect.

I was taught it back in 1981 when I was a Coast Guard Radioman - and SARSAT went on line. SARSAT uses Doppler shift - observing an EPIRB on the ground and by measuring the intensity of the doppler shift can calculate two possible positions of the EPIRB transmitter on either side of the satellite' s polar track....

radio waves do not propagate by interaction within any medium.  so there is no unique frame with which to describe frequency of radio wave.  each observer is his own frame of reference.   sound wave are different,  it propagates by means of a medium. interaction between particles of the medium defines the audio wave.  So the medium forms a special frame of reference for audiowaves.  When measured against that special frame, audiowaves emitted by an object moving with respect to the medium of its propagation definitely has a different frequency and amplitude depending on the direction of propagation.
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#15
RE: The Doppler Effect......
@Brian37

It would be entirely wrong. Those waves only seem to get bigger....in reality, they get smaller*..but our wave isn't getting any bigger or smaller.

If I'm standing still emitting a pulse every second, you'll see a 1 second gap between troughs and peaks - but if I'm moving, it's the one second gap plus whatever speed I'm moving at determining the distance between troughs and peaks. The faster I move, toward you, the shorter the distance between peaks - away from you, further. The peaks are both when, and where, I emit. The troughs are the spaces in between.

The doppler effect.

Stationary /-\-/-\
Towards /\/\
Away /--\--/--\

*because the wave is being constricted to less and less space as the shelf rises, and in light of submarine features. The biggest waves imply a sharp rise in the floor - diverting force upward. That's why shallow water with a shipping trench is so reliable. Still, you lose force pushing against bottom and water will only go so far above level per unit of force behind it - hence, the actual wave is smaller - just more focused.
I am the Infantry. I am my country’s strength in war, her deterrent in peace. I am the heart of the fight… wherever, whenever. I carry America’s faith and honor against her enemies. I am the Queen of Battle. I am what my country expects me to be, the best trained Soldier in the world. In the race for victory, I am swift, determined, and courageous, armed with a fierce will to win. Never will I fail my country’s trust. Always I fight on…through the foe, to the objective, to triumph overall. If necessary, I will fight to my death. By my steadfast courage, I have won more than 200 years of freedom. I yield not to weakness, to hunger, to cowardice, to fatigue, to superior odds, For I am mentally tough, physically strong, and morally straight. I forsake not, my country, my mission, my comrades, my sacred duty. I am relentless. I am always there, now and forever. I AM THE INFANTRY! FOLLOW ME!
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#16
RE: The Doppler Effect......


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#17
RE: The Doppler Effect......
(May 4, 2021 at 1:49 pm)Ranjr Wrote:


Right. So it is all about proximity and relitivity. 

But to someone who isn't the engineer, who is going to precieve the sound as being the same, if you are the observer, ahead of that train coming toward's you, the soundwaves are going to compress and seem louder as the approach, and sound lower and lower the longer it passes you.
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#18
RE: The Doppler Effect......
No one will perceive the sound as being the same in that scenario. A person ahead, on, and behind all hear different things. A sound wave moves, and if the emitter moves as well, the leading edge of the wave is compressed and the trailing edge is enlongated. It's not about things being bigger or louder. Things are louder closer to you because they've lost less force in interaction between yourself and the emitter.

If there are barriers between yourself and the emitter - you won't hear anything at all...and the person behind will hear the same thing they would regardless of whether or not there are barriers between you and the emitter. Just expunge the idea of bigger and louder entirely out of your mind.
I am the Infantry. I am my country’s strength in war, her deterrent in peace. I am the heart of the fight… wherever, whenever. I carry America’s faith and honor against her enemies. I am the Queen of Battle. I am what my country expects me to be, the best trained Soldier in the world. In the race for victory, I am swift, determined, and courageous, armed with a fierce will to win. Never will I fail my country’s trust. Always I fight on…through the foe, to the objective, to triumph overall. If necessary, I will fight to my death. By my steadfast courage, I have won more than 200 years of freedom. I yield not to weakness, to hunger, to cowardice, to fatigue, to superior odds, For I am mentally tough, physically strong, and morally straight. I forsake not, my country, my mission, my comrades, my sacred duty. I am relentless. I am always there, now and forever. I AM THE INFANTRY! FOLLOW ME!
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#19
RE: The Doppler Effect......
(May 4, 2021 at 1:36 pm)Anomalocaris Wrote:
(May 4, 2021 at 8:47 am)onlinebiker Wrote: No.

Doppler effect is obsevable only from an observer' s point of view.

That is - the audio frequency of the moving object (like a train coming towards you) in reality is constant - but APPEARS to the observer as ascending in frequency.


The same can be observed by a moving observer and a stationary source of sound.


Trust me - I KNOW Doppler effect.

I was taught it back in 1981 when I was a Coast Guard Radioman - and SARSAT went on line. SARSAT uses Doppler shift - observing an EPIRB on the ground and by measuring the intensity of the doppler shift can calculate two possible positions of the EPIRB transmitter on either side of the satellite' s polar track....

radio waves do not propagate by interaction within any medium.  so there is no unique frame with which to describe frequency of radio wave.  each observer is his own frame of reference.   sound wave are different,  it propagates by means of a medium. interaction between particles of the medium defines the audio wave.  So the medium forms a special frame of reference for audiowaves.  When measured against that special frame, audiowaves emitted by an object moving with respect to the medium of its propagation definitely has a different frequency and amplitude depending on the direction of propagation.

Uh.... 

You don' t know about radio frequencies propagating in the ionosphere. It is what allows worldwide communication on HF and MF frequencies.
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#20
RE: The Doppler Effect......
The waves that deflect back to the ground and get picked up by receivers are only a part of the total wave, which doesn't require atmosphere as a medium.

One of the first things from earth that will wash over an alien world, is adolf hitler addressing the world at the munich olympics. Probably wont be enough left to make it intelligible, assuming that anyone is even listening, but there it is. Welcome to the universe.
I am the Infantry. I am my country’s strength in war, her deterrent in peace. I am the heart of the fight… wherever, whenever. I carry America’s faith and honor against her enemies. I am the Queen of Battle. I am what my country expects me to be, the best trained Soldier in the world. In the race for victory, I am swift, determined, and courageous, armed with a fierce will to win. Never will I fail my country’s trust. Always I fight on…through the foe, to the objective, to triumph overall. If necessary, I will fight to my death. By my steadfast courage, I have won more than 200 years of freedom. I yield not to weakness, to hunger, to cowardice, to fatigue, to superior odds, For I am mentally tough, physically strong, and morally straight. I forsake not, my country, my mission, my comrades, my sacred duty. I am relentless. I am always there, now and forever. I AM THE INFANTRY! FOLLOW ME!
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