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SPEED CAMERAS…. PRESENTED BY- P.SRI SWATI ROLL-0819431051 H.R.INSTITUTE OF TECHNOLOGY

Speed Cameras Ppt

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Page 1: Speed Cameras Ppt

SPEED CAMERAS….

PRESENTED BY-P.SRI SWATIROLL-0819431051H.R.INSTITUTE OF TECHNOLOGY

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Speed cameras introduced in west london in 1992. A high speed camera is a device used for recording

fast moving objects onto storage media. It uses either a charge-coupled device or CMOS

image sensor, recording 1000 frames per second into DRAM.

Speed camera uses the basic principle of doppler effect and RADAR technology.

Fastest high speed camera has the ability to take pictures at a speed of 200 million frames per second.

INTRODUCTION

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High-speed video cameras offer the advantages of ease of use, live picture set up, reusable recording media, and most Importantly, immediate playback capabilities.

Other applications include: machine diagnostics destructive testing paper manufacturing and converting, and a variety of impact, shock, and drop tests. production line trouble shooting

Why speed cameras?

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Speed camera uses the basic principle of Doppler Effect and RADAR principle.

BASIC PRINCIPLE

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Doppler effect

Sending a fixed frequency signal towards the car and then measuring the efficiencyOf returning signal can deduce the car’s speed.Here,fm= frequency of received signalFe= frequency of transmitted signalV= speed of vehicleα= angle between transmitted signal and path along which vehicle travels

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Radar (short for radio and ranging) works by transmitting a pulse of electromagnetic (EM) energy, also referred to as RF energy at a moving object. Using the Doppler principle the radar gun ‘listens’ to the change in pitch of the radio waves as they reflect off the moving vehicle and thus determines the speed. Similarly, when a train blows its whistle as it passes you – you can hear the change in pitch of the whistle, as the train moves past.

Radar principle

RADAR GUNS

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How it works?

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BLOCK DIAGRAM OF SPEED CAMERA

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DRAM is used for storage of images and data.

Stores each bit in separate capacitor.

Preferred over SRAM.

Advantage being its structural simplicity.

Basic elements in speed cameras

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It is an image sensor that converts optical image into electrical signals.

It is analog device. When light strikes the chip it is held as charge on each photo sensor.

Charges are converted to voltage one pixel at a time.

CCD (Charge- coupled device)

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Motoin of camera Using stepper motor

Motion of cameras is dependent on stepper motor, where camera moves in discrete steps.

Range of step angle- 0.75 to 90 degree.

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A normal motion picture is filmed and played back at 24 frames per second, while television uses 25 frames/s or 29.97 frames/s. High speed cameras can film up to a quarter of a million frames per second by running the film over a rotating prism or mirror instead of using a shutter, thus reducing the need for stopping and starting the film behind a shutter which would tear the film stock at such speeds. Using this technique one can stretch one second to more than ten minutes of playback time (super slow motion). The fastest cameras are generally in use in scientific research, military test and evaluation, and industry.

Frame rate

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The Red Light cameras in are supplied by Redflex, and Gatso (the RLC 36M-MC), first introduced in Queensland in December 1990.  The systems capture two successive 'scene' images. The first image records an infringing vehicle that is just about to enter the intersection during the red signal phase and shows the 'red' traffic signal phase. The second image provides photographic evidence that the vehicle continued into the intersection illegally. The systems then 'find' and 'zoom' the license plate area to give crisp, high-resolution, pixelation-free, license plate images that are easily read to maximize successful prosecutions.

Examples of speed camera

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Forces people to slow down and drive at a reasonable speed.

Can save lives, reduces average road speed.

Keps drivers in line.

Advantages of speed cameras

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A problem for high speed cameras is the needed exposure for the film, so one needs very bright light to be able to film at forty thousand frames per second sometimes leading to the subject of examination being destroyed because of the heat of the lighting.

Disadvantages of speed cameras

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APPLICATIONS

1. For sports analysis

eg. SVSi’s StreamView™ is a portable battery-powered camera designed for quick and easy set-up in the field that captures 640x480 (VGA) images at 200fps. The minimum shutter speed is 1/100,000 or 10-microsecond – fast enough for any sporting

event.

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Speed limit enforcement is the action taken by appropriately empowered authorities to check that road vehicles are complying with the speed limit in force on roads and highways.

Methods used include roadside speed traps set up and operated by the police and automated roadside 'speed camera' systems which may incorporate the use of an automatic number plate recognition system.

Traditionally the police would have used stopwatches to measure the time taken for a vehicle to cover a known distance, but more recently they have had speed guns and automated in-vehicle systems at their disposal.

2. Speed enforcement

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Errors related to speed cameras

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1.Moving Radar mistakes:

The Texas Department of Public Safety produced a comprehensive manual based on the Federal tests. It cautions operators, "...the radar does not generate 'false' readings. Anytime a reading appears, the radar has sensed a signal. The radar operator must be familiar with situations that can produce 'error' readings." If the operator does not detect the error, a ticket will be wrongfully issued.

Here are the radar "errors" detailed by the Texas manual:

How do Police Radar, Laser & Speed Cameras make mistakes?

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Even if the operator aims his antenna properly, radar is still subject to "look-past" error. This is caused by the radar looking past a small reflection in the foreground to read a larger reflection behind. This error is all the more insidious because poorly-trained operators assume it can't happen.  

Texas instructors warn, "It is a widely-held misconception that the reflected target signal received by the radar antenna will always be that of the closest vehicle to the antenna. There are times, due to traffic conditions, that the closest vehicle is not returning the strongest signal."  

The Texas instructors confirm this problem with radar, saying "It is not unfair to say that the reading you register could be a larger, better target three-quarters of a mile down the road."

2. LOOK PAST ERROR

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The radar beam travels in a straight line, neither bending around curves nor following the contour of hilly terrain. If the antenna is not properly positioned, it may seem to clock an approaching car when, in fact, it's clocking another car in the background.

3.Antenna Positioning Error

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  Now we would like to believe that enforcement cameras

are there for our on good and make our roads safer. In general speed camera are perceived to be good idea

because they protect innocent road users and pedestrians. The way in which the speed cameras are currently used is

not to make the driver slow down, obey the speed limit and make the road safe but to catch and penalize the transgressors who may otherwise have slowed down if they have seen as the cameras in advance .i.e. speed camera , as, currently deployed, are not so justifiable .  

These cameras were highly visible then no one would travel by them exceeding the speed limit and they would do their job. Used as they hidden away, they are penalized and contribute little to road safety directly only generating revenue to pay for their installation and maintenance.  

Conclusion

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THANK YOU