College of Canberra Advanced Communications Topics

1695 days ago, 694 views
PowerPoint PPT Presentation
2. Review of Topics. 1 - Basic Concepts of Television Systems2 - Digital Video Sampling

Presentation Transcript

Slide 1

´╗┐College of Canberra Advanced Communications Topics Television Broadcasting into the Digital Era Lecture 1 Television History Analog TV Fundamentals by: Neil Pickford

Slide 2

Overview of Topics 1 - Basic Concepts of Television Systems 2 - Digital Video Sampling & Standards 3 - Digital Audio/Video Stream Compression 4 - Digital Modulation Systems 5 - Transmission System Error Protection 6 - Digital System Parameters, Planning and SI

Slide 3

Digital Media First media frameworks were simple Most media are changing over to computerized Computer stockpiling Music (LP-CD) Telecommunications Multimedia Internet Networking (TCPIP) Radio (DAB) Television (DTTB)

Slide 4

What is Television Images - Black and White Shades of Gray Color - Hue & Saturation Sound - Audio Information Data - Teletext & Other Data Synchronization - Specifies the Timing Transport System - Gets the Above to your TV

Slide 5

History - Ferdinand Braun - CRT 1890 Ferdinand Braun built up the Cathode Ray Tube. 1897 built up the Cathode Ray Oscillograph, the antecedent to the radar screen and the TV tube 1907 First utilization of cathode beam tube to create the fundamentals of TV pictures. He shared the Nobel Prize for material science in 1909 with Guglielmo Marconi for his commitments to the improvement of remote telecommunication.

Slide 6

John Logie Baird - Basic TV Oct 1923 John Logie Baird was the primary individual anyplace on the planet to show genuine TV as conspicuous pictures, momentary development and right degrees in light and shade. Examining was done mechanically with a Nipkow plate. The initial 30 line picture transmitted was a Maltese cross. 1927 he likewise exhibited video recording 1928 transoceanic TV 1937 the communicate of superior quality shading pictures 1941 stereoscopic TV in shading 1944 the multi-weapon shading TV tube, the precursor of the sort utilized as a part of most homes today.

Slide 7

Early Mechanical Approach to TV Mechanical Nipkow circles were utilized to filter the picture and reconstitute the picture at the beneficiary. PE cells were utilized to catch the picture. The issue was synchronizing the plates.

Slide 8

30 Line Mechanical TV

Slide 9

Electronic Television - Farnsworth In 1922 at Age 14 Philo Farnsworth had how to make Electronic Television conceivable. Sept. 7, 1927, Farnsworth painted a square of glass dark and scratched a straight line on the inside. The slide was dropped between the Image Dissector (the camera tube that Farnsworth had concocted before that year) and a hot, splendid, carbon circular segment light. On the beneficiary they saw the straight-line picture and after that, as the slide was turned 90 degrees, they saw it move. This was the main all-electronic TV picture ever transmitted.

Slide 10

Vladimir Zworykin - Iconoscope In 1923 Vladimir Zworykin of RCA made a patent application for a camera gadget, and by 1933 had built up a camera tube he called an Iconoscope . In spite of the fact that Zworykin presented his patent application first after numerous times of fight in court Farnsworth was recognized as the creator of electronic TV. Before the finish of 1923 he had additionally delivered a photo show tube, the "Kinescope"

Slide 11

Significant Television Inventions These innovations were the fundamental premise of the improvement of Television as we probably am aware it today

Slide 12

Aspect proportion 4:3 (12:9) 16:9 First TV presentations were Round Rectangular Rasters less demanding to Generate Television Developed a 4:3 Aspect Ratio Cinematic arrangements are substantially more extensive World now moving to 16:9 Aspect Ratio

Slide 13

Film Has been the most astounding Resolution stockpiling design. Different edge sizes utilized. 16mm, 35mm & 70mm Difficult to deliver, store, handle and show. Effortlessly corrupted because of pollution and scratches. For the most part recorded at 24 fps. For the most part showed at 72 fps (each casing 3x) to decrease glint Use a gadget called a Telecine to change over to TV positions

Slide 14

The Video Signal White Stripe Gray Background 700 mV Front Back Porch 0 mV - 300 mV Sync Pulse Black Stripe Sync Pulse First Television Pictures were Black & White Referred to as Luminance Video alludes to the direct base-band flag that contains the picture data

Slide 15

Video Timing Active Picture 52 us Line Blanking 12 us Sync 4.7 us 1 Line = 64 us SDTV 64 us for each line (15.625 kHz) 52 us Active Picture Area 12 us Blanking and Synchronization Two level adjust beat 300 mV beneath blanking

Slide 16

Frame Rate A Frame speaks to a total TV picture Our simple TV Frame comprises of 625 lines. A Frame is typically involved 2 Fields each containing 1/2 the photo data Our framework has a Frame rate of 25 Hz The Field rate is 50 Hz Pictures showed at 25 Hz display evident glint Interleaving the Fields decreases flash.

Slide 17

Flicker and Judder Flicker and Judder are terms used to portray visual interferences between progressive fields of a showed picture. It influences both Film & TV. On the off chance that the refresh rate is too low, industriousness of vision can't give deception of consistent movement. Glint is brought on by: Slow refresh of movement Information Refresh rate of the Display gadget Phosphor industriousness Vs Motion Blur Judder more often than not comes about because of Aliasing between Sampling rates, Display rates and Scene movement

Slide 18

Interlace To lessen the apparent screen glimmer (25 Hz) on a TV, a strategy called "entwining" is utilized. Intertwining partitions every video outline into two fields; the principal field comprises of the odd output lines of the picture, and the second field of each edge comprises even sweep lines. Join was likewise used to diminish the prerequisite for video transfer speed. It is a type of Compression

Slide 19

Interlaced Vs Progressive Scan Interlaced pictures. - 1/2 the lines introduced each output 1,3,5,7,9,11,13...............623,625 field 1 2,4,6,8,10,12,14.............622,624 field 2 Because the fields are recorded at discrete circumstances this prompts to picture twitter & judder Progressive pictures - every one of the lines sent in the one sweep . 1,2,3,4,5,6,7,8................623,624,625 picture No twitter or judder. Be that as it may, double the data rate.

Slide 20

Progressive Scan Simplifies the addition and sifting of pictures Allows MPEG-2 pressure to work all the more effectively by handling complete pictures Direct preparing of continuously checked sources 24 outline/second dynamic film mode can be given. Helps video transformations with various: quantities of sweep lines quantities of tests per line fleeting inspecting (i.e., picture rate) Progressive Doubles Raw Data Requirement

Slide 21

Resolution The quantity of picture components settled on the show Resolution in TV is constrained by: Capture gadget Sampling Rate Transmission System/Bandwidth Display Device Dot Pitch, Phosphor Focus & Convergence Viewing separation/Display measure Human Eye Typical SDTV frameworks endeavor to exchange 720 pixels for each line

Slide 22

Color Equations for PAL For B&W just needed to transmit Luminance (Y) A Color Image has Red, Green & Blue Components which should be transmitted. We as of now have the Y flag. To stay good with Monochrome sets utilize Y, U & V to speak to the Full Color Picture Y = 0.299 R + 0.587 G + 0.114 B U = 0.564 (B - Y) V = 0.713 (R - Y) Color Difference Signals

Slide 23

A Compatible Color System Y V R G B U

Slide 24

Color Sub Carrier Color Sub-Carrier is included at 4.43361875 MHz Frequency chose to interleave shading data spectra with Luma range More effective utilization of range.

Slide 25

Adding Color to B&W Video A Color Reference Burst on Back Porch And IQ balanced Color Information First TV signs were just Luminance In 1975 we included PAL Color System

Slide 26

Amplitude Modulation

Slide 27

Television Modulation - AM TV utilizes Negative AM Modulation 100% 0% 100%

Slide 28

TV Modulation - AM Min 20% 100% 76% 20% 0% 20% 76% 100% Peak White 20% Black 76% Syncs 100%

Slide 29

TV Modulation - PAL AM 100% 76% 20% 0% 20% 76% 100% Headroom averts Color Over/Under Modulating

Slide 30

Frequency Modulation

Slide 31

Intercarrier Sound A FM subcarrier is added to the AM picture to convey the Audio data FM Deviation 50 kHz utilized with 50 us Emphasis PAL-B utilizes 5.5 MHz Sound subcarrier (L+R) - 10 dB wrt Vision for mono single bearer mode - 13 dB wrt Vision for Stereo & Dual mode second Sound subcarrier for Stereo (R) 5.7421875 MHz (242.1875 kHz above principle sound) - 20 dB wrt Vision transporter 54.7 kHz Subcarrier Pilot tone added to show: Stereo (117.5 Hz) or Dual mode (274.1 Hz)

Slide 32

FM Sound Emphasis dB Frequency (Hz)

Slide 33

TV Modulation - Sound 100% 76% 20% 0% 20% 76% 100% FM Sound Subcarriers Superimpose over the AM

Slide 34

NTSC National Television Systems Committee (NTSC) First overall Color framework Adopted (1966) Generally utilized as a part of 60 Hz nations Predominantly 525 line TV frameworks AM tweak of Luma & Syncs (4.2 MHz) U & V Chroma AM Quadrature Modulated (IQ) Chroma Subcarrier 3.579545 MHz FM or Digital subcarrier adjustment of Sound

Slide 35

SECAM Sequentiel Couleur Avec Memoire (SECAM) Developed by France before PAL 625 Line 50 Hz Color framework Uses AM regulation for Luminance & Sync Line successively sends U & V Chroma segments on exchange lines Receiver requires a 1H chroma postpone line Uses FM for Color subcarrier 4.43361875 MHz Uses FM for sound subcarrier

Slide 36

PAL Phase Alternation Line-rate (PAL) Color System Developed in Europe after NTSC & SECAM Generally connected with 50 Hz Countries Predominantly 625 Line framework AM balance of Luma & Syncs (5 MHz) U & V Chroma AM Quadrature Modulated with V (R-Y) segment reversed on interchange lines Chroma Subcarrier 4.43361875 MHz FM or Digit