TELECOMMUNICATIONS

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TELECOMMUNICATIONS

• Dr. Hugh Blanton
• ENTC 4307/ENTC 5307

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Solutions to Test 1
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1. Definitions

• RFImplies the frequencies where the wavelength,
  l, becomes equal or smaller than the physical
  components in the circuits.
• ContinuousA signal which can take an infinite
  number of different values between a minimum and
  a maximum.

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1. DiscreteA signal which can take only a finite
   number of different value.
2. WirelessA term used to describe
   telecommunications in which electromagnetic waves
   (rather than some form of wire) carry the signal
   over part or all of the communication path.

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1. RandomA rule that assigns one and only one
   numerical value to each sample point in a random
   experiment.
2. DeterministicA model where a set inputs always
   produce the same outputs.

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2. Complex Numbers
a. Express z1 and z2 in polar form.
b. Find z1 and z2 and calculate the
product z1 ? z2 and the
ratio z1 / z2 in polar form.
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3. RF
The presence of the transmission line can be
ignored when
a. l 0.1 m, f 1 GHz transmission line cannot
be ignored!
b. l 1 m, f 1.8 GHz transmission line cannot
be ignored!
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3. RF
c. l 0.01 m, f 0.9 GHz transmission
line cannot be ignored!
d. l 5 cm, f 5.4 GHz transmission line
cannot be ignored!
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4. Smith Chart
a. Reflection coefficient (G)
b. Standing wave ratio (SWR)
c. Input impedance (ZIN)
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4. Smith Chart
d. Input admittance (YIN)
e. Shortest line length
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4. Smith Chart
0.144l
0.494l
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5. Stub Tuning
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6. Uniform Distribution
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7. PDF
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8. Signal

• r(t) s(t) n(t)
• s(t) 5 cos(2p x 1000t ) 10cos (2p x 1100t)
• noise n(t) is white noise with power No 0.05
  watt/Hz
• passband between 990 Hz and 1100 Hz

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9. RC

• The output power spectral density is the input
  density multiplied by the square of the magnitude
  of the transfer function

Note the Fourier transform pair
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10. Ideal Filter