The Doppler Radar due to its uses are most popular in measuring the velocity of the moving object. To understand this concept we need to understand first what is doppler effect. The Doppler effect is the logic given by the Scientist Christian Andreas Doppler from Austria in 1842 which states that the speed of an object can be calculate on the change in frequency received from the destination object. He explains further that there may be following situations of two objects.
Before describing the different situations of two objects I want to clarify here that the Source here is the object from which the Microwave signals are sent and the observer is sitting in the source and destination is the object for which we want to calculate the speed.
1. The source is stationery and Destination is moving.
Two Probability of this Scenario:-
A. The Destination is moving towards the source.
B. The destination is moving away from the source.
2. The source is moving and the destination is stationery
Same two probability:-
A. The Source is moving towards the Destination.
B. The Source is moving away from the Destination.
3. The Source and destination both are moving:-
Again the sub-situations of this Scenario:-
A. The source and the destination are moving in same direction.
(i) The Source and destination are moving in same velocity.
(ii) The source and destination are moving in different velocity.
B. The Source and the destination are moving in opposite directions.
(i) The Source and destination are moving in same velocity.
(i) The Source and destination are moving in same velocity.
(ii) The source and destination are moving in different velocity.
For the easy explanation of the these complex scenarios we consider the examples of train here all the possible scenarios can be covered but aside to the above mentioned scenarios the calculations are based on the below formulas and the base of calculation of speed of Doppler Effect is the change in the frequency which is happening to due to lateral motion of the objects.
I am giving below a sample calculation of the Doppler effects for a source and destination in motion:-
If the Source and destination approaching each other the frequency heard by the Destination (f’) is
f’=f(v+vo)/(v-vs)
If they are moving away from each other
f’=f(v-vo/v+vs)
Where,
v=speed of wave
vo=speed of destination
vs=speed of source
f=frequency at source
f’=frequency observed by destination
Now coming back to the Doppler radar these Radars have multiple usage these are used in navigational aid of ships and Aircraft as well as the Speed Guns of Police which calculates the speed of the speed violators.
These days the Police is also using the video-graphic calculation of the speedsters as it firstly calculates the over speed of the violators also works as evidence to be produced in front of the authority for action against the culprit. This camera calculates the speed based on the speed of object moving from one frame to another frame of the camera lens and hence is a better option as it eradicates the chances of deviation in calculation due to environmental disturbances.
Tele-Columnist!