A EYE FOR THE BLIND

A EYE FOR THE BLIND



Abstract
“The seeds of knowledge may be planted in solitude but must be cultivated in public”. Yes, we should use our knowledge and education for the needs of the people. We like to do something for thousands of our brethren at the loss of their eye sight. It would be a boon in the life of a blind, if there is a scientific invention that would be an apt substitute for his eye sight. This would surely cultivate self confidence and courage for a blind to face the world without the help of others. “There is no study that is not capable of delighting as after a little application to it”. Thus we are greatly delighted in applying our knowledge in creating an apt substitute for the visually handicapped.



Index Terms: RADAR, Microwave radar, Detectors, Doppler shift,
1.0 INTRODUCTION
Radar -- an acronym for RAdio Detection And Ranging -- was invented during World War II and was used to locate enemy planes and ships. The radar device emits a microwave signal and detects the arrival of the reflected signal. The microwave is reflected by objects such as aircraft, and the elapsed time between emission and return is a function of the distance of the object from the radar device. In addition, the speed and direction of a moving object can be determined by analyzing the shift in the frequency of the microwave signal (Doppler effect).
Electromagnetic waves radiated by radar, as well as sound waves, obey the Doppler principal, although electromagnetic waves travel at the speed of light and audio waves travel at the speed of sound. The Doppler effect is a frequency shift that results from relative motion between a frequency source and a listener. If both source and listener are not moving with respect to each other (although both may be moving at the same speed in the same direction), no Doppler shift will take place. If the source and listener are moving closer to each other, the listener will perceive a higher frequency -- the faster the source or receiver is approaching the higher the Doppler shift. If the source and listener are getting farther apart, the listener will perceive a lower frequency -- the faster the source or receiver is moving away the lower the frequency. The Doppler shift is directly proportional to speed between source and listener, frequency of the source, and the speed the wave travels (speed of light for electromagnetic waves).
2.0 HARDWARE USED
Microphone with headset.
Analog to digital and digital to analog converter.
Microwave radar.
Microcontroller.

2.1 Microphone with headset
A sophisticated microphone is used to receive voice commands from the user. The voice information is given to the user through the headset.

2.2 Analog-to-Digital & Digital-to-Analog converter
It’s used to convert the analog voice signals and store it in a digital form. It also converts the digital data stored to analog voice signals and given to the user through the headset.
2.3 Microcontroller
This device is used to recognize the digital voice signals and triggers the actions for the radar. It also sends signals to the user based on the values determined by the microwave radar.

2.4 Microwave Radar
This device is used to read any object, their speed and direction around it. The radar uses microwave signals that are sent and reflected back through which the objects speed and direction are determined.
3.0 HOW RADAR DETECTORS WORK
Think of a radar signal as a beam of light from a flashlight. When you shine a flashlight at an object, your eyes perceive the light reflected from the object. Now imagine yourself as the object being illuminated. You can see the light from the flashlight from a much farther distance than the person with the flashlight could ever hope to see you. That's because the beam loses energy over distance. So while the beam has enough energy to reach you, the reflected light doesn't have enough energy to travel all the way back to where it started.
Radar guns "see" a vehicle by transmitting a microwave pulse. Then they make use of the Doppler Effect: the frequency of the transmitted pulse is compared to the frequency of the reflection, and speed is calculated by using the difference between them.


Fig 1: Speed is calculated when a pulse is reflected to the RADAR transmitter.
That's the idea behind radar detectors. They look for radar "beams" and find them before they can return a strong enough reflection to "illuminate" you. Detectors use something called superheterodyne reception to accomplish this. Radar detectors are essentially microwave radio receivers that make noise or flash lights when they sense an incoming signal on specific frequencies. Superheterodyne reception allows detection of radar around curves or over hills, and it extends detection range straight ahead.
3.1 Moving-mode Radar Doppler
Moving-mode radar is slightly more complicated. The target echo frequency is shifted by the relative speed between the target and radar. Target relative speed (to radar) is the sum of target and user speed for opposite direction targets. For same-lane (direction) targets relative target speed is the difference between target and user speed.
Moving-mode radar depends on two measurements to derive target speed:
(1) GROUND ECHO -- measures user speed
(2) TARGET ECHO -- measures relative (to radar) target speed.
Ground echoes are Doppler shifted by the user velocity. The radar tracks the ground echo to determine user (radar) velocity. The radar uses user velocity and relative (to radar) target speed (target echo) to calculate actual target speed.
Moving Mode Spectrum
Opposite Direction Target

Target Relative Speed to Radar is Vrelative = Vp + Vt
Vt = Vrelative - Vp
Moving Mode Spectrum
Same Direction (lane) Target
Front Antenna

Target Relative Speed to Radar is Vrelative = Vp - Vt
Vt = Vp - Vrelative
Note that on-coming (opposite direction) targets have a negative speed (compared to same-lane targets). This type of radar can (if built-in) distinguish between same-lane targets and opposite direction targets.
BEAM SPREAD
laser or microwave
Beam Spread = 2 R tan ( Beamwidth / 2 )

Beamwidth = 3.5 mR = 0.201°

1.75 feet
0.53 meters
500 feet
152.4 meters

Beamwidth: 3.5 mR (0.201°)
Range: 500 feet (152.4 meters)
Beam Spread: 1.75 feet (0.53 meters)
4.0 BLOCK DIAGRAM

5.0 WORKING
The microphone receives the voice command from the user and gives it to the converter, the converter converts the Analog voice signal into digital. The microcontroller receives this digital signal and matches it with the stored commands, if any match occurs, say for example “cross road” is stored in the microcontroller. If the user speaks out “cross road”, there is the match between these digital voice signals, then the microcontroller triggers the microwave radar to detect the object’s speed and their direction. The information that is inferred from the radar is taken and using the simple logic
If distance>50mts and speed<3km
Play sound “Can Move”
Else
Play sound “Wait”
The sound that is stored in digital is converted to analog using the converter and it is given to the user through the headset.




6.0 CONCLUSION
We have created a model which would be a boon in the life of a blind. This scientific invention would surely cultivate self confidence and courage for a blind to face the world without the help of others.

REFERENCES

[1]www.policetrafficradar.com
[2]www.ieec.com
[3]www.crutchfielsadvisor.com
[4]www.bushnell.com