COSC 85 | Finals | Lecture Flashcards
entities that convey meaning
data
electric or electromagnetic encoding of data
signals
refers to information that is continuous and take on continuous values
analog data
refers to information that has discrete states and take on discrete values
digital data
can have infinite number of values in a range
analog signal
can have only a limited number of values
digital signal
completes a pattern within a measurable time frame, called period, and repeats that pattern over subsequent identical periods
periodic signal
completion of one full pattern is called
cycle
changes without exhibiting a pattern or cycle that repeats over time
aperiodic signal
a sine wave, cannot be decomposed into simpler signals
simple periodic analog signal
composed of multiple sine waves
composite periodic analog signal
most fundamental form of periodic analog signal
sine wave
the absolute value of its highest intensity
amplitude or peak amplitude
peak amplitude is normally measured in
volts (v)
refers to the amount of time, in seconds, a signal need to complete 1 cycle
period
refers to the number of periods in 1 second
frequency
describes the position of waveform relative to time 0
phase or phase shift
another characteristic of a signal traveling through a transmission medium
wavelength
shows changes in signal amplitude with respect to time
time-domain plot
concerned with only the peak value and the frequency
frequency-domain plot
can be decomposed into a series of simple sine waves with discrete frequencies
periodic composite signal
can be decomposed into a combination of an infinite number of simple sine waves with continuous frequencies
non-periodic composite signal
the range of frequencies contained in a composite signal
bandwidth
the transmission of signals that vary discretely with time between two values of some physical quantity, on value representing binary 0 and 1
digital transmission
these data is assigned to one voltage level to binary 1 and another for binary 0
digital data, digital signal
these data such as video and voice are often digitized to be able to use digital transmission facilities
analog data, digital signal
the representation of digital information by a digital signal
digital-to-digital encoding
in this scheme, all the signal levels are either above or below the axis
unipolar
the voltage are on the both sides of the axis
polar
there are three voltage levels: positive, negative, and zero
bipolar
positive voltage defines bit 1 and zero voltage defines bit 0
unipolar encoding
the level of signal depends on the type of bit that it represents
non return to zero-level
Inversion of the voltage level that represents 1 bit
non return to zero-inverted
Signal changes between bits
return to zero
an encoding scheme in which signal changes at the middle of the bit interval but does not return to zero
biphase
this encoding scheme is a combination of RZ and NRZ-L
manchester
this encoding scheme is a combination of RZ and NRZ-I
differential manchester
a neutral zero voltage represents binary 0
alternate mark inversion
Bit 1 is encoded as zero voltage and the bit 0 is encoded as alternating positive and negative voltages
pseudoternary
a condition where the receiver’s information does not match with the sender’s information
error
in this error, only 1 bit in the data unit has been changed
single bit error
Data Unit is received with more than one bit in corrupted state
multiple bits error
2 or more bits in the data unit have changed
burst error
the detection of errors caused by noise or other impairments during transmission from the transmitter to receiver
error detection
the simplest technique and inexpensive to detect the errors
vertical redundancy check
a single bit error is detected by
vertical redundancy check
Organizes the original data in the form of a table or 2D Matrix
two-dimensional parity check
is generated at the sender’s side
checksum
it subdivides the data into equal segments of n bits each
checksum generator
appended to the end of data unit so that the resulting data unit becomes exactly divisible by a second, predetermined binary number
cyclic redundancy check
