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WorksheetsDigital Communications
Total questions: 20
Worksheet time: 55mins
Law gives the relationship between time, information capacity, and bandwidth.
I = ktB
C = 2B log2M
C = B log2(1 + S/N)
SR = 2fmax
Ignoring noise, the _________________________ theorem gives the maximum rate of data transmission for a given bandwidth.
I = ktB
C = 2B log2M
C = B log2(1 + S/N)
SR = 2fmax
The ____________________ limit gives the maximum rate of data transmission for a given bandwidth and a given signal-to-noise ratio.
I = ktB
C = 2B log2M
C = B log2(1 + S/N)
SR = 2fmax
The ____________________ Rate is the minimum sampling rate for converting analog signals to digital format.
I = ktB
C = 2B log2M
C = B log2(1 + S/N)
SR = 2fmax
Natural Sampling does not use:
a sample-and-hold circuit
true binary numbers
a fixed sample rate
an analog-to-digital converter
The immediate result of sampling is:
a sample alias
PAM
PCM
PDM
Foldover distortion is caused by:
noise
too many samples per second
too few samples per second
all of the above
Which is true about aliasing and foldover distortion?
They are two types of sampling error.
You can have one or the other, but not both.
Aliasing is a technique to prevent foldover distortion.
They are the same thing.
Quantizing noise (quantization noise):
decreases as the sample rate increases
decreases as the sample rate decreases
decreases as the bits per sample increases
decreases as the bits per sample decreases
The dynamic range of a system is the ratio of:
the strongest transmittable signal to the weakest discernible signal
the maximum rate of conversion to the minimum rate of conversion
the maximum bits per sample to the minimum bits per sample
none of the above
Companding is used to:
compress the range of base-band frequencies
reduce dynamic range at higher bit-rates
preserve dynamic range while keeping bit-rate low
maximize the useable bandwidth in digital transmission
In North America, companding uses:
the Logarithmic Law
the A Law
the α Law (alpha law)
the µ Law (mu law)
In Europe, companding uses:
the Logarithmic Law
the A Law
the α Law (alpha law)
the µ Law (mu law)
____________________ modulation is the most commonly used digital modulation scheme.
Pulse Code
Pulse Width
Pulse Amplitude
Pulse Delta
Adaptive delta modulation can transmit PCM-quality voice at about ____________________ the bit rate of PCM.
half
2 times
3 times
4 times
lA PCM system has the following parameters: a maximum analog input frequency of 4 KHz, a maximum decoded voltage at the receiver of + 2.55 Vp, and a minimum dynamic range of 46 db. Determine the following; minimum sample rate, minimum no. of bits used in the PCM code, resolution and quantization error.
(a)
Determine the number of bits required for
a binary code to represent 110 different possibilities. Also determine the coding efficiency.
(a)
Use Hartley's Law to find how much time it would take to send 100,000 bits over a channel with a bandwidth of 2,000 hertz and a channel constant of k = 10.
(a)
Use the Shannon-Hartley theorem to find the bandwidth required to send 12,000 bits per second if the number of levels transmitted is 8.
(a)
What is the Shannon Limit of a channel that has a bandwidth of 4000 hertz and a signal-to-noise ratio of 15?
(a)
