B Doppler effect on electromagnetic waves in a car

[abdossamad2003]

Is the doppler effect on electromagnetic waves receive by cell phone in fast car and so somebody talk with cell phone in fast car view this effect

 

[Motore]

Is the doppler effect visible to someone talking on a cell phone in a fast car?

Visible in the sense they will percieve a difference when talking on a phone in a fast car versus talking when standing on the streat? No.

 

[Ibix]

Is the doppler effect visible to someone talking on a cell phone in a fast car? The electromagnetic waves that the phone receives are affected by the doppler effect.

Ask the next police radar speed trap you see. They measure your speed by measuring the Doppler effect in radio waves bouncing off your car.

 

[Ibix]

...but you need sensitive apparatus to detect a frequency shift. Your red car won't look blue at highway speeds (although a friend claims to have seen a bumper sticker at CERN that said If this sticker appears blue you are driving too fast![/color]).

 

[vanhees71]

I'd not drive that fast! Travelling close to the speed of light relative to the cosmic microwave background shifts its typical frequency from the microwave region to $\gamma$ rays, which is not too healthy ;-).

 

[Baluncore]

Is the doppler effect on electromagnetic waves receive by cell phone in fast car and so somebody talk with cell phone in fast car view this effect

A car traveling at 60 mph ≈ 96 kph ≈ 27 m/s, while light travels at about 300 Mm/s. The Doppler effect could be one part in 300M / 27 ≈ 11 million. That is similar to the initial accuracy of the mobile phone frequency, before it locks onto the cell site. So Doppler frequency will not be important during acquisition, nor during the synchronous operation of the communications.

 

[tech99]

Radio waves received on a moving vehicle are subject to Doppler Shift and also to flutter caused by the combination of direct and reflected propagation paths. The radio system is designed to minimise problems caused by propagation effects. There are five generations of cell phones and each has its own scheme to allow operation on the move. We always need a median received signal which is adequately above thermal noise, say 20 dB, and we need a modulation scheme which is not too sensitive to incoming frequency. We may also use some form of diversity (frequency, time, position, two-path etc) and error correction. As cellphones are now digital, the path effects are not going to be directly audible other than poor quality and loss of service.