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Understanding Bandwidth and Noise
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Understanding Bandwidth and Noise
Understanding Bandwidth and Noise
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1
Question
What is bandwidth?
Answer
The difference between the highest and lowest frequencies contained in the information or allowed to pass through a channel.
2
Question
What are the requirements for bandwidth?
Answer
It must be large enough to pass all significant information frequencies and equal to or greater than the bandwidth of the information.
3
Question
What is Information Theory?
Answer
A theoretical study of the efficient use of bandwidth to propagate information through electronic communications systems.
4
Question
What is Information Capacity?
Answer
A measure of how much information can be propagated through a communications system, a function of bandwidth and transmission time, and represents the number of independent symbols that can be carried through a system in a given unit of time.
5
Question
What is a Binary Digit or bit?
Answer
The most basic digital symbol used to represent information.
6
Question
What is bit rate?
Answer
The number of bits transmitted during one second, expressed in bits per second (bps).
7
Question
What is electrical noise?
Answer
Any undesirable electrical energy that falls within the passband of the signal.
8
Question
What are the two general categories of noise?
Answer
Correlated (related to the signal) and uncorrelated (present whether there is a signal or not).
9
Question
What are the results of noise?
Answer
Hiss in loudspeakers, snow/confetti on TV CRTs, and bit errors in digital transmission.
10
Question
What is uncorrelated noise?
Answer
Present regardless of whether there is a signal present or not.
11
Question
What are the two categories of uncorrelated noise?
Answer
External and internal noise.
12
Question
What is external noise?
Answer
Noise that is generated outside the system. The three primary sources are atmospheric, extraterrestrial, and man-made.
13
Question
What is atmospheric noise?
Answer
A naturally occurring electrical disturbance that originates within the Earth's atmosphere; commonly called static electricity.
14
Question
What is extraterrestrial noise?
Answer
Electrical signals that originate from outside Earth's atmosphere; sometimes called deep space noise.
15
Question
What are the two categories of extraterrestrial noise?
Answer
Solar and cosmic.
16
Question
What is Solar Noise?
Answer
Noise generated directly.
17
Question
What causes solar noise?
Answer
Sunspot activity and solar flare-ups.
18
Question
What is another name for cosmic noise?
Answer
Black body noise.
19
Question
Give examples of man-made noise.
Answer
Commutators in motors/generators, automobile ignitions, fluorescent lights.
20
Question
What are the three primary kinds of internally generated noise?
Answer
Shot, transit time, and thermal.
21
Question
What is thermal noise associated with?
Answer
The rapid and random movement of electrons within a conductor due to thermal agitation.
22
Question
Across what spectrum is thermal noise uniformly distributed?
Answer
The entire electromagnetic spectrum.
23
Question
List alternative names for thermal noise.
Answer
Johnson noise, thermal agitation noise, agitation noise, and white noise.
24
Question
What causes shot noise?
Answer
The random arrival of carriers at the output element of an electronic device.
25
Question
What is another name for shot noise?
Answer
Transistor noise.
26
Question
What causes transit time noise?
Answer
Any modification to a stream of carriers as they pass from the input to the output of a device produces an irregular, random variation.
27
Question
What is partition noise?
Answer
Occurs whenever current has to divide between two or more electrodes and results from the fluctuations in the division.
28
Question
What is another name for flicker noise?
Answer
1/f noise, pink noise.
29
Question
To what is thermal noise proportional?
Answer
The product of the bandwidth and temperature.
30
Question
What is the formula for noise power?
Answer
N = kTB (where N is noise power in watts, B is bandwidth in Hertz, k is Boltzmann's constant, and T is absolute temperature in Kelvin)