UNT RTVF 1310 - Chapter 3 Notes 2013 Part 1 (9 pages)

Previewing pages 1, 2, 3 of 9 page document View the full content.
View Full Document

Chapter 3 Notes 2013 Part 1



Previewing pages 1, 2, 3 of actual document.

View the full content.
View Full Document
View Full Document

Chapter 3 Notes 2013 Part 1

129 views


Pages:
9
School:
University of North Texas
Course:
Rtvf 1310 - Persp on Brdcst Tech
Unformatted text preview:

Chapter 3 Audio and Video Technology Basic principles Basic Principle of Media Technology Facsimile Technology All modes of mass communication based on this process of copying Fidelity a way to describe how faithfully a facsimile represents the original High Fidelity is reproduction that closely approximates the original signal Radio waves can be used to transmit facsimiles of pictures and sounds Transduction Transduction the process of changing one form of energy into another form For example Capturing sound of a bird chirping using a microphone involves the transduction of sound waves into electricity In the case of image light into electronic current Transmitting the sound and image of the chirping bird involves transducing the electrical energy into electromagnetic energy Digital The Good the Bad and the Ugly Digital signals are subject to less noise interference than analog signals Compression making larger video and audio files smaller Pro Digital files can be more easily manipulated Con Digital files can be more easily copied and distributed illegally Two basic concepts that are involved in the process of transduction Oscillation and wave form Oscillation Oscillation a basic concept of audio and video signal processing Examples Vibration of air produced by speech and other sources make sound vibration of light frequencies make up all the images we see Electromagnetic waves used for transmission of radio TV satellite are also oscillate The rate of oscillation of a radio sound or light wave defines its frequency Wave form Waves may be described in terms of frequency and amplitude Frequency is the number of waves that pass a given point in a given time Frequency is usually measured in hertz Hz The higher the frequency the shorter the wavelength Amplitude is the height or depth of the wave from its normal position Frequency Response How well a radio reproduces a range of audio frequencies is an example of describing its frequency response How faithfully television represents the original image is thought of in terms of picture resolution CDs can reproduce the entire range of audio frequencies that the human ear can hear 20 to 20 000 Hz AM stations cannot reproduce all the frequencies the human ear is capable of hearing FM radio comes much closer etc The FCC determines a station s bandwidth when it determines what frequencies that stations can use bandwidth impacts info capacity and thus sound and picture quality Signal generation recording transmission Signal Generation and Recording Mechanical and Digital Technologies For example sound signals are generated by two main transduction processes Mechanical microphones phonograph records and tape recorders Electronic CDs DVDs and computer files Digital Recording Technology Sound and images that has been transduced into electrical current are sent to a device that converts them into a series of samples Once in digital form they are coded and stored ELECTROMAGNETIC SPECTRUM Upper end of the spectrum includes visible light which ranges from red to violet Above violet ultra violet Below red infrared Radio Bands in the Electromagnetic Spectrum Low Navigation signals Very Low VL Time signals long range military comm Medium Frequency MF 107 AM channels air and marine radio High Frequency HF International Shortwave CB and Ham radio Very High Frequency VHF FM radio and TV channels 2 13 Ultra High Frequency UHF UHF Most DTV channels police radio radar and weather satellites Super High Frequency SHF Ku and C band satellites Microwave transmission air navigation Extremely High Frequency EHF special military communications Spectrum Management Spectrum management the process of defining and keeping track of what frequencies will be assigned and licensed for special purposes Allocated for specific purposes by the ITU International Telecommunications Union Allotted to countries Assigned by each country s licensing organization e g FCC The process known as transduction is used at several points to accomplish modulation of the carrier frequency Radio AM Broadcast Service Assignment Method Frequency Search Band MF Medium Frequency 535 1705 kHz Channel Width 10 kHz 1075 1085 1080 kHz AM Continued Operate on 60 clear 41 regional or 6 local channels Min Max Power 250 50 kw Stations are designated as class A highest power 10 to 50kw B 5 to 25 kw C regional 500 to 5000w local 250 to 1 000w FM Broadcast Service Assignment Method FCC Assignment Table Part 73 FCC Rules Regs Band VHF Very High Frequency 88 108 mHz Channel Width 200 kHz 97 1 mHz 97 0 97 2 SCS Subsidiary Communications Service Mulitplexing Stereo HD FM Radio Classified as A up to 3kw HAAT max 300 ft B up to 50kw HAAT max 500 ft C 100kw max HAAT 2 000 ft Low Power FM up to 100w HAAT max 100 Min Max Power 100 w 100 kw HD Radio Does it stand for anything FCC approved iBiquity s HD radio technology in 2003 HD radio technology was developed and is owned by iBiquity Digital Corporation In band on channel IBOC IBOC signals use the same AM or FM bandwidth as the station s analog signal in band digital information is contained within the station s signal on channel Advantages of HD radio over analog radio Higher quality sound Multicasting Auxiliary information artist name of song weather news traffic Improved reception Current analog signals will remain HD Radio is FREE HD radio receiver is needed to pick up digital portion of signal Industry projects that radio will go all digital once technology matures Currently 1 500 radio station broadcasting in HD IBOC uses COFDM Coded Orthogonal Frequency Division Multiplexing to multiplex a digital stream on to the FM or AM carrier Satellite Radio Digital audio radio service DARS satellite delivered direct to home or car DARS is a form of DAB In 1992 FCC allocated space in S band 2 3 GHz of frequency spectrum for nationwide broadcasting of DARS In 1997 FCC auctioned two segments in the S band spectrum for DARS THE WINNERS XM began service in November 2001 SIRIUS launched service in July 2002 Merged 2008 Television Television Classifications VHF television Channels 2 thru 13 UHF television Channels 14 thru 83 UHF channel assignments include new digital television channels DTV Each television channel occupies 6 Mhz of bandwidth How does Television Work Depends on two characteristics of the human eye Persistence of vision Trichromatic nature of vision Persistence of Vision Film uses this by presenting the viewer with 24 single images per second Prior to DTV


View Full Document

Access the best Study Guides, Lecture Notes and Practice Exams

Loading Unlocking...
Login

Join to view Chapter 3 Notes 2013 Part 1 and access 3M+ class-specific study document.

or
We will never post anything without your permission.
Don't have an account?
Sign Up

Join to view Chapter 3 Notes 2013 Part 1 and access 3M+ class-specific study document.

or

By creating an account you agree to our Privacy Policy and Terms Of Use

Already a member?