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Network+2009
Signaling Methods
28
Computer Networking
Professional
03/03/2010

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Term
Analog Signal
Definition
Carries information in the form of a continuous wave. In networking analog signals are most often generated by electrical current
Term
Waveform
Definition
The size, shape and other characteristics that describe the analog signal and information it carries
Term
Sine Waves
Definition
A smoothly oscillating curve that is the result of calculating the sine of the angles between zero and 360 degrees and plotting the results
Term
Amplitude
Definition
The height(or depth) of the wave from the midpoint between the top and the bottom of the waveform
Term
Cycle
Definition
One complete oscillation of an analog signal
Term
Frequency
Definition
The number of complete cycles per second in the wave, measured in hertz
Term
1 Hz is equal to ?
Definition
One cycle per second
Term
Phase
Definition
A description of where a wave's cycle begins in relationship to a fixed point
Term
Wavelength
Definition
The distance between to successive peaks in wave form
Term
Digital Signal
Definition
Has only two values a binary 1=on and a binary 0=off
Term
A bit is equal to?
Definition
a single binary 1 or 0
Term
A Crumb is equal to ?
Definition
Two Bits
Term
A Nibble is equal to ?
Definition
Four Bits
Term
A Byte is equal to ?
Definition
8 Bits
Term
Modulation
Definition
A high frequency oscillating signal is used as a base, or carrier, for information. Then a lower frequency data signal is superimposed over the carrier waveform.
Term
Demodulation
Definition
When the signal reaches its destination, the receiver decodes the signal, removing the data from the carrier
Term
Codec
Definition
Is software or hardware that codes and decodes data to and from analog format.
Term
What is DAC?
Definition
Digital to Analog Conversion
Term
What is ADC?
Definition
Analog to Digital Conversion
Term
Synchronous Communications
Definition
A byte is sent in a standardized time interval where the receiver assumes that one byte is transmitted every interval.The devices must start and stop their reckoning of these intervals at the same time
Term
Asynchronous Communications
Definition
Special start and stop bit patterns are inserted between a byte of data. By watching for these patterns the receiver can distinguish between the bytes of data
Term
Are Digital Transmissions Modulated?
Definition
No they are not modulated over a carrier. Data is converted into a digital waveform using "on-off keying," or "Manchester Encoding"
Term
On-Off Keying
Definition
Is a digital transmission encoding scheme in which a change in voltage from one state to another within a predetermined interval is symbolized by a 1. No voltage change is symbolized by a 0. The sender must syncronize its clock with the sender by watching for the 1's
Term
Manchester Encoding
Definition
Is a way to overcoming the limitations of on-off keying. It represents the transition from positive to ground with a 0 and from negative to positive voltage IN THE MIDDLE OF THE BIT PERIOD it designate a 1
Term
Serial Data Transmission
Definition
Bits are transmitted ONE PER CLOCK CYCLE over a single tranmission medium
Term
Parallel Transmission
Definition
Multiple bits are transmitted over multiple transmission lines. Multiple bits even multiple bytes are transmitted per clock cycle
Term
Baseband Transmission
Definition
DIGITAL SIGNALS are sent via a DC pulse over a single UNMULTIPLEXED signal channel(Uses TDM)
Term
Broadband Transmission
Definition
ANALOG SIGNALS are used to send data over a transmission medium using a portion of the bandwidth. Signals are wave of electromagnetic or optical energy.(Uses FDM)
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