Digital and Analog

1. Digital and Analog • Analog • involves continuous method of signal recognition • similar to line on continuum • signal changes shape and degrades in quality when transferred from one place to another • Digital • responds to discrete on-off impulses • in essence many samples of analog signal, written down in set order • bits of information transfer with little loss of quality • Compression • numbers that appear second time in same part of digital signal do not need to be recopied • allows more information to be packed into less space

2. Radio Production • Microphones • omnidirectional – pick up sound from all directions • cardioid – pick up mainly from one direction • Music and sound effects • compact discs (CDs) • digital audio tape (DAT) • MiniDiscs (MDs) • computer hard drives • Audio board • allows volumes to be mixed and adjusted • mixed sound sent from board to transmitter • News reporters • usually need only microphone, sound recorder, and cellular phone • can record and take material back to station, or transmit over phone

3. Television Production • TV studio and cameras • windowless soundproof room with sets • grid – holds and positions lights overhead • camera consists of viewfinder, lens, and electronic system • CCDs (charge-coupled devices) – light-sensitive chips that change image gathered by lens into electronic form • Control room • computer graphics generator • audio board – mixes sound inputs • switcher – selects and mixes video inputs • take – quick change from one picture to another • dissolve – slow change of pictures • fade – transition between picture and black • key – laying one picture on top of another • VCRs and servers play back material on monitors • Single-camera style – one or two people on news crew

4. Film Production • Shooting techniques • single-camera shoot – one camera shoots same scene over and over from various angles • shooting on location – eliminates need to build set, but lacks control of studio • Editing • computer editing nonlinear – any shot can be placed anywhere on final product and moved easily • if movie is shot on film, it is transferred to video for editing, then copied back to film or used as reference to cut original film negative

5. The Electromagnetic Spectrum • Frequencies • measured in hertz – one cycle per second • human ear capable of hearing 16 – 16,000 Hz • kilohertz (kHz) = one thousand hertz; megahertz (MHz) = one million hertz; gigahertz (GHz) = one billion hertz • Radio waves • 30 kHz – 300 GHz • capable of carrying sound and pictures • below infrared rays, light waves, ultraviolet rays, X rays, gamma rays, and cosmic rays on electromagnetic spectrum • non-media uses – garage door openers, burglar alarms, secret reconnaissance functions • after World War II, FCC allocated TV frequencies into very high frequency (VHF) and ultra-high frequency (UHF)

6. Terrestrial Radio Broadcasting • Definitions • “terrestrial” radio waves travel only short distances in atmosphere • cell phones, cordless phones, AM and FM radio • Modulation • at transmitter, radio energy is modulated – superimposed on carrier wave that represents station’s frequency • amplitude modulation (AM), 535 – 1705 kHz • height of carrier wave varied to fit sound wave characteristics • more subject to static, since it appears at top and bottom of wave cycle • can travel great distances since it is lower on spectrum; travels enormous distances at night, when waves bounce back to earth from ionosphere • frequency modulation (FM), 88 – 108 MHz • frequency of carrier wave varied • frequency closer to that of light, making its signals line of sight, easily blocked by objects • stations have greater bandwidth – can produce higher fidelity and are adaptable to stereo • independent signals can be multiplexed on FM signal and broadcast to special receivers

7. Terrestrial Television Broadcasting • Bandwidths • analog TV station uses 600 times more bandwidth than AM station • digital signal can be compressed to smaller bandwidth • digital HDTV uses just as much bandwidth as analog because of added lines and wider screen aspect ratio • Channels • placed at various points in spectrum • breaks between VHF Channels 4 and 5 and Channels 6 and 7 • two adjacent over-air channels cannot be used unless break comes between them • UHF Channels 14 to 69 – digital stations will occupy this spectrum space in future • Multiplexing • teletext and closed captioning broadcast along with regular station signal • multiplexing easier on digital channels, will increase in the future • Microwave • higher frequency than radio or TV, travels about 30 miles • used to transmit signals from studios to transmitters and news trucks to stations

8. Satellites • Satellite operation • transponders – hold audio, video, and data information • C-band – 4-6 GHz, carries most cable programming • Ku-band – 11-14 GHz, transmits DBS • synchronous satellites – orbit synchronized with speed of earth’s rotation • satellite casts footprint over section of the world from 22,300 miles away • History of satellite broadcasting • AT&T launched Telstar I, 1962 • HBO placed pay service on RCA’s Satcom I, 1976 • local TV stations began satellite news gathering (SNG) • direct broadcast satellite (DBS), mid-1990s • digital audio radio service (DARS), 2001 • satellite-based radio delivered directly to automobiles • uses pulse code modulation – encodes sound in digital form • international media affected by satellites

9. Wire Transmission • Wire uses • low-tech video-on-demand in hotels • phone calls and email messages • cable TV and SMATV • Cable TV • head end – services placed on wire and buried or hung on telephone poles • since wires are physically connected, cable can be interactive • not subject to same interference as broadcast TV • Types of wires • copper twisted-pair – longtime standard in telephone industry • coaxial cable – used by cable TV when systems first built • fiber optics – digital information carried through glass strand on light produced by laser diodes

10. Pick Up and Carry • Bicycling – physical transport of program or movie from one place to another • Some public access programs – tapes carried to several different cable TV systems • Videos, DVDs, and CD-ROMs reach consumers through shipping to wholesale houses or retail stores • Film industry • thousands of prints of films made for physical distribution • international openings staggered so other countries can use old prints from U.S.

11. Exhibition • Movie theaters • projector pulls frames through light that shines through lens • sound usually rides beside picture frames and is sent to multiple speakers • Radios – have grown smaller • TV sets • electron gun at back of picture tube sends electrons to phosphor screen • supplemental audio program (SAP) – viewer can choose between two separate audio tracks, usually English and Spanish • remote controls • projection TV – allows screen display to become larger with conventional picture tube • liquid crystal display (LCD) – played role in developing both larger and smaller TV sets