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Lightning Detector Design Competition

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Kelvin Ng

on 11 May 2013

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Transcript of Lightning Detector Design Competition

Median blur
Get the brightness of the changed part of the image
Brightness is higher than a certain level Lightning
Take the lightest changed point as reference
Calculate direction Team B
HKTA Tang Hin Memorial Secondary School Lightning Detector Design Competition Three algorithms
One will be implemented
Some are not implemented because of practical difficulties Algorithms Algorithms Implemented Using Only Coils and Amplifiers
Build several detectors
Each of them consists of a coil and an amplifier
Get the strength detected by each detector Ratio of two sides of the triangle
Calculate directions (and even positions) using trigonometry Inputting Data to a Computer Arduino Board Sound Card Not Implemented ~We have found that this algorithm is wrong~ Originally, we decided to: But... This is unachievable in Mathematics Detectors Ratio of the two sides The angle being calculated Using Coils, Amplifiers and a Webcam Use two coils and connect each to an amplifier
Intersect them at 90°
Connect them to amplifiers so that the signal will be larger
Find an angle from 0° to 90° by trigonometry
Don't know which quadrant the lightning is falling in
Find the quadrant with the webcam
Use the lightest point as the reference
Calculate the direction with the above data Advantages Theoretically, accurate direction can be got
Difficult to be disturbed
Only be disturbed by electronic devices
Not always exist
Usually, it is not disturbed by a sudden strong light, such as fireworks
Webcam images will be processed only when the coils indicate that there is a lightning
Background is subtracted, so a static strong light will not be regarded as a lightning Difficulties in Practical Situation Difficulties of using Webcam
Talk about it later
No direction can be detected
May be due to the reflection of EM wave ~So, we are unable to implement it~ Two intersect coils a b Top view Use a Coil, an Amplifier and a Webcam Connect the coil to an amplifier
Direct the webcam to the sky vertically
Stick a fisheye to the webcam so as to broaden the view of the webcam
Check for the direction with the webcam when the coil has received some pulses
Detect uncountable infinite many directions x y View of the Webcam Audio Cable Connect the coil to the left or right channel of the audio cable
Plug the audio cable to the audio input port of the computer Sound Card Advantage Get the 'audio' signal from the sound card
Set a threshold
Signal is larger than the threshold
regard it as a lightning Stable
No external device is needed
Need not care about low level stuff as audio libraries can be used Arduino Board Plug the coil to the analog input port
Write the signal ( to the voltage, an integer from 0 to 1023) to the serial port
The computer receives the signal from the serial port Plug the coil here Disadvantages Unstable
Wrong signal is received
Not suitable for long operation
Too hot Webcam
(with fisheye lens) Coil Programme Startup Running Retrieve Data Type ./main in the command line Lightning happened at <time>.
Direction: <direction> deg will show on standard output when a lightning occur Besides showing the data on standard output, data is also stored at
Photos are stored at
View the data directly
Through the webpage:
http://lightning.localdomain record/record.txt record/<time>.png Difficulties: Inputting Data to a Computer Two methods
One of them is used Members Chan Chak Hong
Chan Lok Hin
Ho Ho Man
Lai Siu Kei, Keith
Ng Kai Wing, Kelvin
Teacher: Wong Shun Tak Ways to Improve Use two detectors to locate the positions Position? We can locate the position! The End Amplifier? No amplifiers
No significant advantages
Not tuned correctly

We have made an amplifier: Some lightnings cannot be captured by the webcam
Blocked by buildings
Solution: Put on the high mountain
View is not large enough
Solution: Use an expensive fisheye lens which can provide a view of nearly 180°
Nothing has to be changed
EM wave detection does not sync with webcam image capturing
Frame rate of webcam is low
Useless for lowering sampling rate of EM wave detection
Solution: Use a camera with higher frame rate Image Processing Background subtraction
Dynamic background
Get the changed part 'Audio' Processing Threshold
Signal is larger than a certain level
Do image processing The coil is simply like that as an antenna coil Background Finger on Background Audio cable Coil Audio cable Fisheye lens Without fisheye lens With fisheye lens Lightest point 211°
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