help me for measure the speed of a car

[hosseinfeizy]

measure speed of car importance

Hi
I proposed an idea for my ultrasound project, ultrasound in cars.
please help me.

 

[saeed_pk]

Ultrasonics do not have long range so you have very narrow window of operation.
either you use Ultrasonic, laser or uWave
There are two methods.
One to measure doppler's shift and second is Equal time interval ranging.
in second method make a good range meter and calculate range for say every 100 ms make average and calculate the speed by v=d/t simple formula but remember in real practical environment this speed is not accurate due to presence of cosine error in your way of measurments

 

[hosseinfeizy]

would you please explain more about first method?

 

[hugo]

Hi
I proposed an idea for my ultrasound project, ultrasound in cars.
please help me.

This is a nice tutorial about building a digital speedometer using a GPS module :

https://www.sparkfun.com/commerce/tutorial_info.php?tutorials_id=123

 

[saeed_pk]

to use GPS is a good idea
when u use ultrasonic sensor in car and you are moving you must have an obstruction/ hurdle from which USonic has to reflect back.