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24 Cards in this Set

  • Front
  • Back
What are the 3 elements of a sine wave
amplitude
phase
frequency
What is a concentrator
a device that allows several terminal data sources to share a single DATA LINK ONE AT A TIME
What type of communication sytem would perform remote batch processing
Time sharing

pg. 1-10
In what device is the data buffer used to absorb the difference in data transfer speeds between the CPU and the telephone line
Communications controller


PAGE 2-7 & 2-8 READ
WHAT IS THE FORMULA FOR CENTER FREQUENCY
UPPER FREQUENCY + LOWER FREQUENCY/2

1100hz + 100hz/2

CENTER FREQUENCY = 600HZ
A modem transmits 3,000 bits per second. Each signal element represents three bits of binary information. What is the baud rate of the modem
1000bps
What are the Characteristics of a data communication system
1. Direct machine-to-machine communication
2. occurs through a common link
3. involves the movement of encoded information by means of an elctrical transmission
What are computer-to-computer Systems
Communication networks that allow separate computers to share common data
What type of information can not be transmitted across telephone lines
Digital signals
What are the key elements of a teleprocessing network
1. central computer
2. software
3. communications link
4. remote terminal equipment
Explain Store-and-Forward Message Switching Systems
A communications systems that enable message to be transmitted in a step-by-step method using switching computers

pg. 1-8
What are the classifications of communications systems
1. Information storage and retrieval
2. Computer-to-Computer
3. Store and Forward message switching
4. time sharing
What are the communication channels (link)offered by telephone companies
1. Narrow band
2. voice grade
3. wide band
What is real time
An event recorded or reported at the actual time it occurs
What is a Code System
A system of symbols and rules representing information. That has the following characteristics:
* common to both sender and receiver

*it is efficient, uses minimum energy to transmit maximum energy
Describe wide band channels
a combination of a number of voice facilites and range from 5khz to 5mhz. And are often leased for business use.



pg 2-25
What is a multiplexer
permits SERVERAL terminal data sources to share a SINGLE data link at the same time
What is an Information storage and retrieval systems
A computer based communications system consisting of a terminal that monitors or provides information to a common database via the telephone
Descsribe narrow-band channels
Narrow-band facilities are used primarily for teletype communications and carry up to 75 bits per second.
Describe voice-grade channels
Voice grade channels are the most common communications link and have a bandwidth for voice communications. and can transmit data from 300 t0 10,000 bits per second

pg 2-25
WHAT IS THE FORMULA FOR BAND WIDTH
3000HZ (upper frequency) - 300hz (lower frequency) = 2700 HZ

bandwidth = 2700hz
What are the elements of a communication system
1.message source
2. medium
3. sink
What are the characteristics of a Time-sharing communications systems
1. Uses Data communication for remote acces
2. Responds immediately to a remote user's inquiry
3. Services many users at the Same time
4. A REMOTE USER can introduce new programs
What is a modem
A device that impresses digital information onto a carrier frequency.
** also called a modulator/demodulator **