CHAPTER 3 Flashcards
Data must be transformed to __________ signals to be transmitted.
electromagnetic
Data can be ________ or _________.
analog or digital
Analog data take __________
values.
Digital data take _________ values.
continous and discrete
Signals can be analog or digital. Analog signals can have an _______ number of values in a range; digital , signals can have only a ___________ number of values.
infinite, limited
in data communications, we commonly use _______and ________ signals
periodic analog signals and nonperiodic digital signals.
________and ________ are the inverse of each other.
Frequency and period
_______________ is the rate of change with respect to time
Frequency
_____________describes the position of the waveform relative to time O.
Phase
A complete sine wave in the time domain can be represented by ____________
one single spike in the frequency domain.
A single-frequency sine wave is not useful in data communications; we need to send a composite signal, a signal made of many simple sine waves.
true or false
TRUE
According to Fourier analysis, any composite signal is a combination of simple sine waves with different ________, __________ and _________
frequencies, amplitudes, and phases.
The bandwidth of a composite signal is the difference between__________and __________
the highest and the lowest frequencies contained in that signal.
_________ is a composite analog signal with an infinite bandwidth.
A digital signal
Baseband transmission of a digital signal that preserves the shape of the digital signal is possible only if we have a low-pass channel with an infinite or very wide bandwidth.
true or false
true
If the available channel is a bandpass channel, we cannot send a digital signal directly to the channel; we need to convert the digital signal to an analog signal before transmission.
true or false
true
For a noiseless channel, the Nyquist bit rate formula defines the theoretical maxi- mum bit rate. For a noisy channel, we need to use the Shannon capacity to find the maximum bit rate.
true or false
true
_________, ___________ and _________ can impair a signal.
Attenuation, distortion, and noise
____________ is the loss of a signal’s energy due to the resistance of the medium.
Attenuation
_________________ is the alteration of a signal due to the differing propagation speeds of each of the frequencies that make up a signal.
Distortion
___________ is the external energy that corrupts a signal.
Noise
______________ defines the number of bits that can fill the link.
The bandwidth-delay product
_____________ defines how long it takes for an entire message to completely arrive at the destination from the time the first bit is sent out from the source.
The latency or delay
We can say that latency is made of four components: _________, ___________, ___________ and ____________
propagation time, transmission time, queuing time and processing delay.
_________ is a measure of how fast we can actually send data through a network.
throughput
