elex test 1

• display system
• vertical system
• horizontal system
• trigger system

• beam finder
• focus
• intensity
• scale illumination
• trace rotation

• i cm intervals
• 8 vertical x 10 horizontal
• 1/5 minor divisions

• controls amplitude & appearance
• adjusts vertical position
• input coupling (AC/DC)
• vertical sensitivity
• volts/div
• Ch.2 Inversion
• Chop and Alt modes

• time aspect
• horizontal position
• sweep rate
• sec/div
• horizontal magnification
• delayed sweep

• trigger level and slope
• holdoff
• auto/normal trigger

• band pass filter: 430 - 750 THz
• lens/focus ~ lens
• aperture ~ pupil/iris
• film(CCD) ~ retina

• rods - light sensor
• cones - colour sensor
• central part most sensitive

ability to distinguish b/w adjacent points of about 1/40th of 1 degree

• distinct flicker - 5 Hz
• noticeable flicker - 25 Hz
• imperceptible flicker - 30 Hz

clear perception of objects, 15^o

• ratio b/w H and V dimensions
• NTSC (National Television System Committee) - 4:3
• HDTV - 16:9

• shades of light and dark
• scene motion reproduced as picture motion
• natural colour
• 3D displacement required

brain's response to one or more wavelengths of light being sensed

intensity of the light being observed

purity of the colour being observed

• hue: tint control
• saturation: colour control
• brightness: contrast & brightness controls

• red
• green
• blue

saturated red + green

saturated red + blue

saturated green + blue

saturated red + green + blue

0% red + green + blue

50% red + green + blue

Y = 0.299R + 0.587G + 0.144B

• cyan
• orange

17 MHz to 8 MHz

mix the R-Y and B-Y signals with a 3.58 MHz local oscillator to incerase the colour signal frequency so noise generated will be too high frequency to be noticed by the eye

• by-product of increasing the frequency, humps below and above the carrier signal frequency on the frequency spectrum
• generally suppressed otherwise would "beat" with the sound carrier to produce visible interference at 920 kHz

phasor produced by the R-Y and B-Y colour signals, transmitted with the luminance level (Y)

• luminance level (Y) + chrominance signal (C) transmitted
• 3.58 MHz phase shifted

• angular displacement: hue
• magnitude: degree of saturation

• I = orange
• -I = cyan
• Q = magenta
• -Q = green

made of steel, placed b/w electron guns & phosphor coated inner surface of picture tube to make a higher accelerating voltage (20-30 kV)

• w/in the horizontal blanking interval
• EAV (end of active video)
• SAC
• current line number
• 18-bit frame check sequence

signal is encoded as MPEG-2 in the studio

• monitor
• memory
• graphics adapter
• application program

can be used with a number of standards operating at different picture (vertical) frequencies

• # pixels/line
• # lines/frame
• speed the display technology can turn on/off the phosphor or LCD/plasma device
• scanning & retrace time of a line

• H freq
• --------
• V freq

• dot freq
• ---------
• H. freq

distance between adjacent pixels, in mm

dots per square inch, for printers

provide timing signals and refresh actions to constantly update the visual display device

• only allow CPU access during retrace
• use fast RAM
• use dual-port RAM
• CRT controller higher priority of access than CPU

• video graphics adapter
• IC system developed by IBM
• display up to 256 colours on screen at a time
• analog system

• new: 15 pin D connector
• old: 9 pin D connector

• digital visual interface
• allows digital monitors to be used with PCs

• make use of machine code mnemonics or
• use direct numerical coding in hex or
• enter assembly language code

80 columns 25 rows

• correction when the light strikes the sensor at an angle
• reading = treading if the light strikes the sensor at a perpendicular angle x cosine of the angle of incidence

• incandescent - brighter at sides than at base or the other end
• fluorescent - uniform radiation along the tube and no radiation from the ends

• correlated colour temperature (CCT)
• colour rendering index (CRI)
• source efficacy
• lamp lumen depreciation
• rated average life

• chromaticity of the source
• <3000K - appear orange-white, "feels" warm
• >4000K - appears blue-white, "feels" cold
• >5000K - daylight

degree of resultant colour-shift objects undergo when illuminated by the light source as compared with the colour of those same objects when illuminated by a reference source of comparable colour temperature

ratio of lumen/watt (light output per electrical power unit input)

• reduced light production due to aging
• caused by deterioration of phosphor, filament, cathode, or electrode

statistically determined estimate of average or median operational life

• A - arbitrary
• G - globular
• ER - eliptical reflector
• PS - pear shaped

• uses ballast to provide proper starting voltage and operating current
• base conducts electricity to the cathode (filament) to heat it up
• filament produces electron cloud & its heat vapourizes the Hg vapour inside the bulb
• Hg energized to a higher state, release photon when drops back to shell
• photons collide with phosphor on inside of bulb
• light emitted

• better control of gas discharge process
• greater efficiency
• longer life
• operate at 25-60kHz (compared to powerline freq)

• form of data compression
• same data value occurs in many consecutive data elements are stored as a single data value and count

transmitting the difference between each value and its predecessor, in place of the value itself

error b/w the actual signal & the binary result

• Digital Imaging and Communications in Medicine
• 1024 levels (10 bits)

• Tagged Image File Format
• very large files, mostly uncompressed
• can produce compressed lossless files with LZW algorithm

• Graphical Interchange Format
• 256 colours
• run-length encoding

• Bit Map Picture
• invented by Microsoft

• Joint Photographic Experts Group
• stores images in a 24 bit format
• allows variable degrees of compression

employs data structures of a binary tree to create smaller codes for common characters

• symbol: I
• unit: candela (cd)
• light intensity from a source in specific direction

• symbol:
• unit: lumen (lm)
• intensity of light from a source

• symbol: E
• unit: lux (lx, lumen per square meter)
• density of luminous flux on a surface
• luminous flux/area

• symbol: M
• unit: lumen per square meter (lm/m²)
• flux density leaving a surface

• symbol: L
• unit: candela per square meter (cd/m²)
• nrg reflected in a particular direction or passed through translucent material
• luminous intensity/(Acosa)

• symbol: Q
• unit: lumen-second (lm.s)
• luminous nrg emitted or received during a period of time from a source whose luminous flux output varies with time

• photoemissive: release of electrons from photosensitive surface when light hits that surface
• photoconductive (junction): alteration of semiconductor material by radiation so its conductance is increased; fast response but low sensitivity
• photoconductive (bulk): higher sensitivity than junction, slower response
• photoelectric: radiation alters semiconductor material and generates a small voltage; Si - 0.5V, Ge - 0.1V