Comm 240 Exam 1

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Antennas (Radiators): Electrical conductors with Alternating Current; Most efficient when height=radio wavelength being broadcast
Netword Cloud: shows the connections of all the different hosts
Doodle: Meeting collaborative figures out available times for meeting other members
Frequency [Radio Wave]: the rate of alternating current (slow or fast)
Penetration: best measure to how many households have access to a given technology; percent of marketplace use
AM Radio: 3 Parts: Carrier Wave; Adjacent Sidebands (USB/LSB are directly proportional to range of frequencies); Bandwidth
Compression: removes redundancy in signals and saves bandwidth with increased capacity
Wave Propogation: positive and negative aspects of a wave act as its poles. as each wave is emitted, it repels/propels the preceding wave before it causing radio wave transmission
3 layers of technology: Hardware, Software, Content
FM radio Stations are classified by: power and height from the ground
Direct Waves: Higher Frequency (VHF, UHF, SHF, EHF); Towers are less expensive; Prone to interference when line of sight is blocked
picture quality: determined by resolution and amount of colors allowed in picture (bits)
Social Information Processing Theory: people make adoption decisions and other evaluations of technologies based upon objective characteristics of the technology
Binary Digits: Bits, count but skip all numbers without 1 or 0 in it. 1, 10, 11, 100, 101, 110, 111....
AdobeFlash: a popular tool for adding clientside animation and interactivity to webpages -more control than Javascript; -supports unique application and graphic formats (makes manipulation of graphical objects easier but text harder)
Pulse Code Modulation (PCM): a common audio encoding method that demonstrates a 3 step analog to digital conversion process
Diffraction: Waves bending
Uses and Gratifications Theory: explores the uses and benefits of technology
Power [Radio Wave]: the amount of electric current put into the radio wave (a little or a lot) - amplitude
Internet radio relies on: Internet Protocol (IP) HTTP is not necessary for simply audio
Frequency Modulation (FM): carrier changes from high to low frequency based upon wave length/freq
FM Radio Spectrum: channels are 20 kHz wide... 20x wider than AM; use guardbands to protect from interference; simplexing/multiplexing
FM Radio: 1933 Armstrong modulated frequency which produces a clear sound
SHF, EHF: needs line of sight; parabolic dish used to focus incoming radio waves onto antenna in the middle
Representing a Picture: draw a grid of rectangles over an image to create pixels
Motivating Factors: provide an incentive for the adoption of new technology
Innovators: buy new technology while very expensive
Satellite Radio: broadcast from space; crystal clear or not there; monthly subscription
Radio/TV: grew together to reach almost 100% penetration. no displacement.
Lossy Compression: represent bitstrings that are only slightly different with a single so that info is lost (e.g. JPEG)
Google Docs: stores documents online (like a microsoft office on the internet)
Java: a sophisticated platform independent programming language -most programs are computer specific (extremely flexible but slow/hard to program)
Motion Pictures: Thomas Edison (Late 19th Century)....10 year gaps between technological discoveries=sounds, color, widescreen, 3D, IMAX, digital
resolution: how fine the grid is.... smaller squares gives the illusion of continuity
Binary Codes: represents quantized signal level
Problems with AM: very inefficient (alot of wasted power with LSB); poor sound quality (low bandwidth/lots of static)
Sound Recordings: Phonautograph (Late 19th Century), Edison's phonograph, Records, CDs, MP3
Software: instructions guiding the operation of the hardware
Carrier: dictates where on the electromagnetic spectrum wave is going
Peer to Peer (P2P): each host acts as a client in some exchanges and a server in others (ex IM, limewire)
Sky Waves (Skip Waves): Medium Frequency; Daytime/Nighttime Differences; Go through Ionosphere during day (very effective) but skips and causes interference at night
Sales Figures: not a reliable way of comparing how many people actually use technology (ex varying prices)
Anti-Aliasing Images: Use color to make up for missing resolutions (makes for a smoother appearance)
Digitization: the process of converting a continuous analog signal into a binary digital signal of 0s and 1s
Frequency Influence on Wave Propagation: long wavelength=wave follows curvation of Earth's surface; short wavelength=wave travels in a straight line and ignores Earth's curvation
VHF, UHF: line of sight helps, but not required; antenna places on roof, hill, supporting tower and doesnt need to be as tall
HDTV: standard built on top of digital broadcasting technology (DTV) with higher definition and sound
Network: computers exchanging information with one another
World Wide Web: a system of interlinked hypertext documents (one type of content transported over the internet)
LF, MF, HF Antennas: does NOT need a line of sight to transmit; almost always use all steel towers, typically 1/4 height of wavelength
S shaped Curve for Adoption of Innovation: innovators, major adopters, laggards
Aliasing: false frequencies in the reconstructed signal as a result of undersampling
Digital Signal: discrete wave that is either on or off -rectangular waveform-
3 Measures for Measuring Media Access and Consumption: Sales Figures, Number of Units Sold, Penetration
3 types of radio waves: ground, direct, sky/skip
Content: messages communicated through or mediated by the lower layers
Sociotechnical System: communication systems are largely defined by societal factors: laws, technical standards, social conventions, individual skills
Bandwidth: range of frequencies used by a signal. more bandwidth=better sound quality
Quantized Signal: has a fixed number of levels
Enabling Factors: often focus on new technical capabilities, but social factors as well
AM Radio Stations are classified by: power
Digital Audio Recording: converting from analog to a digital signal
Ground Waves: Lower Frequency (LF, MF, HF); Hug Earth's Surface; Most stable type of wave; Low interference; Large expensive towers; Best conditions for travel distance: lower freq, higher power, wetter ground
Telephone: Alexander Graham Bell (Late 19th Century).... wireless msgs, mobile radio phone for Detroit police cars, cellphones, displacement of landlines
Digital Radio: less bandwidth and less compression; multiple audio streams on a single station with no interference but low quality when signal is weak
Limiting Factors: opposite to enabling factors that constrain communication... can be technical or social
Sampling: occurs at regular intervals (digital isnt choppy because of large sampling per second)
Domain Name System (DNS): handles IP address look ups
Compression Drawbacks: over compression can cause reduction of quality and aliasing in audio and video
Yammer: sharing files across a secure company network
Modulation: allows transmission of information using waves by altering characteristics of a periodic carrier signal to enable it to carry information
Why convert to digital?: 1. no static 2. transmission errors can be fixed 3. compression requires less bandwidth 4. enhanced security encryption
Inhibiting Factors: opposite of motivating, these provide a disincentive for buying new technology (too expensive)
Digital Audio Playback: converting back to original analog signal (bit string to soundwave via digital to analog converter and speakers)
Audion: 1906 invented by Lee de Forest- Early Radio... allowed for signal amplification but was still difficult to hear
Radio Frequency Spectrum: Managed by the FCC - LF, MF, HF, VHF, UHF, SHF, EHF
Encryption: "Lock" digital data automatically using a secret key (e.g. Rotation Cipher = Rot n)
Convergence: refers to the unification of diverse communication technologies (integration of mass media, telephone and computers)
Javascript: a simple language for providing client-side web page interactivity (can do complex things but is not as flexible)
Laggards: those who do not purchase new technologies until it is completely necessary
Music Sales: consistently rose until late 1990s due to illegal downloading/file sharing
Internet: a heterogenous mix of computer networks that speak a common language and agree to help deliver messages for each other
Digital TV: FCC transition Februrary 17, 2009
TCP/IP: the common language for transporting messages across the internet
History of Technology: telephone, motion pictures, sound recordings, radio, television, computers, video games
Bits can be: recorded and transmitted
Motion Picture Representation: a sequence of images
Client-Server: hosts in an exchange have different responsibilities -client display results; -servers return results (search engine, email)
Amplitude Modulation (AM): varies the amplitude or power of a signal while frequency of carrier is left untouched
URL: a text based addressing system linked to IP address
HTTP: a language built on top of TCP/IP that is used to deliver web content (send/receive webpages)
Analog Signal: continuous wave that vary in amplitude and rate -curvilinear waveform-
Wavelength: distance a wave travels in one period; inversely proportional to frequency
Radio Data Systems (RDS): allows compatible radio to display metadata (song titles, station call letters) and transmits with FM stations using multiplexing
Federal Communication Commission (FCC): They allocate which technologies and which companies can broadcast on which wavelengths
Modulating Wave: message that you want to send
Pixel: each picture cell is represented with a bitstring that codes the colors of that cell
Etherpad: collaboration editing tool
IP Address: a unique 32 bit number for every computer on the internet
Protocol: a set of rules stating how communication can take place between computers and electronic documents
Factors for the AM to FM Radio Move: 1. better sound quality 2. decreasing availability of AM channels 3. FCC restricted many AM stations from simulcasting their signals on FM to open up more of the spectrum for FM
Electromagnetic Spectrum: ranges from 1 Hz to infinite.... only small lower freq section can be used for communication transmission
Evite: Online party list and RSVPs
Original Signal: has continuous amplitudes
Magnetic part to Electromagnetic energy: AC creates radiation
Host: computer connected to other computers by a network
Hardware: the physical equipment
getdropbox: access/share files between computers
# of Units Sold: better measure than sales figures but can also over inflate usage (radio in a house vs. radios actually used)
Lossless Compression: eliminate long strings of identical bits or bit that do not change between frames
Properties of Radio Waves: Power, Frequency. Independent of one another.
CODECs: Coder and Decoder: software used to convert digital back to analog for playback (must use same standards as recording)
The FCC Mandate: FCC est. by Comm Act of 1934 assign radio station frequencies that do not interfere with each other
Electromagnetic waves can be: recorded and transmitted
Alternating Current: electric current that repeatedly and regularly alternates
The AM Dial: carrier waves occur at 10kHz intervals from 540kHz to 1600kHz
Major Adopters: very rapid uptake with lower price (the average American)
Google Calendar: Online calendar with daily events
Oversampling: extra samples add no new information (sounds the same) but the file is bigger than need be
ASCII: stand way of representing text characters with number or bits (series of letters can be represented as collection of adjacent bitstrings)
Movie Theater Attendance: steadily increased until 1950 with advent of television
Analog Audio Recording: Converting one analog signal into another (soundwave to electromagnetic wave via microphone)
Critical Mass Theory: value of technology goes up with number of users (ex. being first to use facebook is not so great... more users have greater value for each user.)
Undersampling: important variation in audio signal between samples... causes aliasing
Hertz (Hz): Frequency measurement; the number of complete wave cycles in a second. kHz=cycles per thousandth of a second
HTML: a text based language used to describe webpages (hypertext markup language)
Regenerative Circuit: 1913 Edwin Armstrong invented this radio amplifier so home radios could be heard across a room
Analog Audio Playback: Converting back to original analog signal (EM Wave to soundwave via speaker)
Displacement: when one technology replaces a previous one
Network Speed Depends on....: Speed of connection to the internet and speed of messages on the internet

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