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Synchronized Strobe for Video Camera Jeff Baskett & Jason Zubo Project Advisor: Dr. Irwin Contents of Presentation Project Summary Standards Project Description Parts List Schedule of Tasks Project Summary

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Synchronized strobe for video camera l.jpg

Synchronized Strobe for Video Camera

Jeff Baskett & Jason Zubo

Project Advisor: Dr. Irwin


Contents of presentation l.jpg
Contents of Presentation

  • Project Summary

  • Standards

  • Project Description

  • Parts List

  • Schedule of Tasks


Project summary l.jpg
Project Summary

  • We are designing a circuit to control a DMX512 strobe that will be synchronized with the shutter on a video camera.

  • Based on the shutter speed of the camera, we plan to fire a strobe during each frame to freeze high-speed motion preventing any blurring effects.

  • The only inputs into the system will be the video synchronized signal from the camera and the intensity of the light read by the sensor.

  • The outputs will be the intensity of the light from the strobe.

  • The recorded image will be analyzed to determine the effectiveness of the system.



Slide5 l.jpg

Block Diagram

Timing signal and 250K clock

Timing Circuitry

DMX

Interface

Viewed image

Intensity

Adjustment

Synchronized

Signal

Power

Compensation

Strobe

Video Recorder

Light input

Light

Sensor

Image

Reflected Light

Video input (reflected light)


Block diagram l.jpg
Block Diagram

Timing signal and 250K clock

Timing Circuitry

DMX

Interface

Viewed image

Intensity

Adjustment

Synchronized

Signal

Power

Compensation

Strobe

Video Recorder

Light input

Light

Sensor

Image

Reflected Light

Video input (reflected light)


Video camera l.jpg
Video Camera

  • Sony XC-75 CCD Black and White Video Camera Module

    • We will have to determine from where in the camera we will get the shutter signal

    • The input to the camera will be the reflected light from the image


Slide8 l.jpg

Block Diagram

Timing signal and 250K clock

Timing Circuitry

DMX

Interface

Viewed image

Intensity

Adjustment

Synchronized

Signal

Power

Compensation

Strobe

Video Recorder

Light input

Light

Sensor

Image

Reflected Light

Video input (reflected light)


Timing circuitry l.jpg
Timing Circuitry

  • Delay Circuitry to insure strobe fires during time when shutter is open.

    • This delay will be calculated and implemented with an RC circuit

  • 250 KHz clock signal

    • This will be used to shift the bits of data to the strobe at the necessary 250 Kbaud rate as specified by DMX

    • This will be implemented using a 555 timer


Slide10 l.jpg

Block Diagram

Timing signal and 250K clock

Timing Circuitry

DMX

Interface

Viewed image

Intensity

Adjustment

Synchronized

Signal

Power

Compensation

Strobe

Video Recorder

Light input

Light

Sensor

Image

Reflected Light

Video input (reflected light)


Sensor l.jpg
Sensor

  • We will be using a photodiode to sense the light output from the strobe

  • Circuit design for converting photodiode output to useable levels has yet to be explored


Slide12 l.jpg

Block Diagram

Timing signal and 250K clock

Timing Circuitry

DMX

Interface

Viewed image

Intensity

Adjustment

Synchronized

Signal

Power

Compensation

Strobe

Video Recorder

Light input

Light

Sensor

Image

Reflected Light

Video input (reflected light)


Power compensation l.jpg
Power Compensation

  • Window Detector

    • This will determine the need to increase or decrease the intensity of the strobe

    • The measured value of intensity from the sensor is the input and will be compared to ideal intensity levels which will be determined experimentally

    • The output will be a signal denoting the need to increase or decrease the intensity


Slide14 l.jpg

Block Diagram

Timing signal and 250K clock

Timing Circuitry

DMX

Interface

Viewed image

Intensity

Adjustment

Synchronized

Signal

Power

Compensation

Strobe

Video Recorder

Light input

Light

Sensor

Image

Reflected Light

Video input (reflected light)


Strobe l.jpg
Strobe

  • Snapshot DMX/D

    • Requires differential input of DMX512 signal

    • Will operate in DMX mode where intensity is the first byte of data received, duration is second, and the rate is set by DMX refresh


Slide16 l.jpg

Block Diagram

Timing signal and 250K clock

Timing Circuitry

DMX

Interface

Viewed image

Intensity

Adjustment

Synchronized

Signal

Power

Compensation

Strobe

Video Recorder

Light input

Light

Sensor

Image

Reflected Light

Video input (reflected light)


Dmx interface l.jpg
DMX Interface

  • Increment or decrement strobe intensity based on output from power compensation circuitry.

  • Use preset duration value (found experimentally) to maximize strobe effectiveness.

  • Output appropriate DMX signals to strobe using 250Kbaud timing clock.


Dmx interface18 l.jpg
DMX Interface

  • The rate is determined by DMX refresh

    • The strobe will fire at the end of a packet of data

  • Sample packet of data

Duration Data

Break - 88us

Intensity Data

Mark after break - 8 us

Idle line

Stop Bits for data

Start bit for data

Start code - 44us


Dmx interface19 l.jpg
DMX Interface

Power Compensation

Output

Stop

Bits

Duration

Presets

Intensity

Counter

Start

Bits

64-bit Shift Register

RS-485

Interface

64-bit

Counter

Differential DMX-512

output to strobe

250 KBaud clock


Slide20 l.jpg

DMX Interface

Power Compensation

Output

Stop

Bits

Duration

Presets

Intensity

Counter

Start

Bits

64-bit Shift Register

RS-485

Interface

64-bit

Counter

Differential DMX-512

output to strobe

250 KBaud clock


Slide21 l.jpg

DMX Interface

Power Compensation

Output

Stop

Bits

Duration

Presets

Intensity

Counter

Start

Bits

64-bit Shift Register

RS-485

Interface

64-bit

Counter

Differential DMX-512

output to strobe

250 KBaud clock


Slide22 l.jpg

DMX Interface

Power Compensation

Output

Stop

Bits

Duration

Presets

Intensity

Counter

Start

Bits

64-bit Shift Register

RS-485

Interface

64-bit

Counter

Differential DMX-512

output to strobe

250 KBaud clock


Slide23 l.jpg

DMX Interface

Power Compensation

Output

Stop

Bits

Duration

Presets

Intensity

Counter

Start

Bits

64-bit Shift Register

RS-485

Interface

64-bit

Counter

Differential DMX-512

output to strobe

250 KBaud clock


Slide24 l.jpg

DMX Interface

Power Compensation

Output

Stop

Bits

Duration

Presets

Intensity

Counter

Start

Bits

64-bit Shift Register

RS-485

Interface

64-bit

Counter

Differential DMX-512

output to strobe

250 KBaud clock


Tradeoffs l.jpg
Tradeoffs

  • Large shift register and counter would be difficult to implement and control.

  • Microprocessor is capable of controlling timing of data as well as transmission of data.

  • Window detector output will interface directly with a microprocessor without A/D conversion, thus eliminating round off error.

  • Software will make the project easy for future students to modify or add features.


Microprocessor l.jpg
Microprocessor

  • Interrupt driven timing control of data to follow DMX 512 standards

  • Will output serial data to RS-485 interface as shift register would


Parts list l.jpg
Parts List

  • Strobe - Snap Shot DMX/D

  • Video Camera - Sony XC-75 (in stock)

  • RS-485 Interface - MAX1480C

  • Sensor - EG&G Vactec PhotoDiode (in stock)

  • EMAC Evaluation Board (in stock)

  • Sensor amplification-AD823 dual precision, 16MHz, operational amplifier. LM741 dual in-line operational amplifier. (in stock)


Schedule of tasks l.jpg
Schedule of Tasks

  • Finish project by Student Expo

  • Other than that, we’re not sure how long things will take.


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