1. ICON College of Technology and Management
Course: BTEC HND in Electrical and Electronics
Engineering (Communications)
Unit: 35, Radio Communication Engineering, Session: Feb 2011
Course work, Word limit: 3000.
A broadcast company enrols you as a consultant to design an audio broadcast system covering
greater London. This broadcast system will enable a user to select between twenty frequency
multiplexed music and chat show discussion channels, where each channel delivers up to 10KHz of
high quality audio. The broadcast transmitter is placed in central London, and your plan and
design must include: A detailed consideration of modulation schemes based on preassigned
spectral allocations purchased, design of a superhetrodyne receiver, geographic planning for
repeating stations considering path loss, and finally, a critique and recommendation of the
transmission parameters for the system. In this context, address the following:
Q1. (a) Briefly describe how a radio wave may propagate over land and in the Earth’s Atmosphere
highlighting clearly the causes and effects of each method of propagation. Focus strongly
on how the atmosphere and earth curvature affect ground and sky wave propagation.
(b) Explain that the loss in free space is a function of distance and frequency by deriving the
associated equation from first principles. Convert the final equation into dB and sketch a
diagram (graph) showing the attenuation versus distance in free space.
(c) Let a terrestrial radio communication link be described by a two ray propagation model.
Find a linear model of the form Pr(dB) = Pr(dB) + KdB - 10νlog10(d) that will describe the
propagation characteristics past the critical distance. The parameters of the link are: Path
loss exponent = ν, Transmitter power = 1W, carrier frequency = 423MHz, height of
transmitter antenna = 20m, height of receiver antenna = 2m. Let the reflection coefficient
over smooth ground be equal to 1. Note, KdB in this case is a constant that describes the
received power at a distance = critical distance. Following this model, complete the
following:
(i) Calculate the SNR at the critical distance if we assume the antennas are isotropic. If
the antennas are isotropic, assume an antenna noise temperature of 270K. Compare
this SNR to the case where the transmitter and receiver antennas have a gain of
10dB. Assume in the case of the receiver antenna that a prominent sidelobe
pointing to ground exist causes the antenna noise temperature to increase to 330K.
Note, the bandwidth = 10KHz for one audio channel. Other Parameters are:
Boltzmann’s constant, k = 1.38×10-23
J/K, Low Noise Amplifier Noise Figure =
-2dB, Mixing Circuit Noise figure = -10dB, and Filter Noise Figure = -8dB.
(ii) As part of the investigation, it would be useful to estimate where, close to the
transmitter, does free space path loss dominate (i.e. distance regions where the
reflected ray makes negligible contribution to the signal power). If you make the
assumption that ground reflection is negligible when the reflected path contributes
less than 10% towards the total signal power, calculate the distance from the
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2. transmitter such that this communication assumption is accurate. Assume a
perfectly flat earth.
(d) Evaluate the effect of ionized layers in the ionosphere on high frequency sky wave
propagation in the range of 3 MHz to 30 MHz and indicate if a sky wave will be a factor
in the system design using the preassigned frequencies.
Q2. (a) Explain the necessity of modulation in the case of a radio system? Illustrate the process of
amplitude modulation and double-sideband suppressed carrier amplitude modulation using
a sinusoidal signal. Describe how amplitude modulation differs from frequency and phase
modulation?
(b) Explain the process of designing single sideband with suppressed carrier amplitude
modulation technique using balanced modulators and 900
phase shift circuits. Indicate
how a Hilbert transform technique can be used in single sideband modulation.
Q3. Explain the working principles (with the aid of block diagrams) of:
(a) Amplitude modulated transmitters.
(b) Frequency modulated transmitters.
(c) Carefully describe the differences in system performance between AM and FM in terms of
bandwidth, transmit power, tolerance to interference, and noise immunity.
(d) The company intend to bid on an auction for a paired spectrum of 412MHz – 414MHz and
422MHz – 424MHz as licensed by OFCOM. To lend validity to the bid, you must describe
how you intend to meet the out of band spectral emission requirements and what coverage
would a single transmitter be able to yield given the transmitter power requirements. The
details of the auction are given in the URL:
http://www.ofcom.org.uk/radiocomms/spectrumawards/completedawards/award_412
/documents/im/.
Sketch a diagram showing how you would allocate the channels and frequencies, including
guard bands to meet specific out of band emissions. What will be the transmit power of the
system?
Q4. (a) Evaluate the performance of a superheterodyne receiver compared to a TRF receiver.
Draw the block diagram of a superheterodyne receiver and describe its principle of
operation.
(b) Explain the importance of using a low noise amplifier at the front end of an RF receiver
and illustrate answer with practical examples.
(c) Describe the implementation process and demodulation of an amplitude modulated (AM)
audio signal and how we may form a transceiver based system for two way communication.
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3. Relevant Information
1. Submission deadlines
Initial Submission 05-05-2010
Feedback given 12-05-2010
Final Submission 19-05-2010
2. Outcome of the Units
Outcomes Assessment criteria for pass. To achieve
outcome, a learner must demonstrate:
Questions
reflecting the
Outcome
1. Investigate
amplitude and
angle
modulation.
• Analyze and describe amplitude modulation
(P1.1, M1.1, D1.1).
• Analyze and describe single sideband
amplitude modulation (P1.2, M1.2, D1.2).
• Analyze and Describe Angle Modulation
(P1.3, M1.3, D1.3).
Q2
2. Explain the
principle of
radiation and
propagation of
transverse
electromagnetic
wave.
• Explain the principles of Electromagnetic
Radiation (P2.1, M2.1, D2.1)
• Describe the Electromagnetic Spectrum in
terms of frequency and wavelength (P2.2,
M2.2, D2.2).
• Describe the structure and nature of the
ionosphere with reference to daily, seasonal
and long-term changes (P2.3, M2.3, D2.3).
• Explain the modes of propagation of radio
waves of different frequencies (P2.4, M2.4,
D2.4).
Q1
3. Investigate the
operation of a
radio transmitter.
• Explain the legal requirements for transmitter
operation (P3.1, M3.1, D3.1)
• Derive a system diagram for an amplitude
modulated transmitter and explain the
function of each stage (P3.2, M3.2, D3.2).
• Derive a system diagram for a frequency
modulated transmitter and explain the
function of each stage (P3.3, M3.3, D3.3).
Q1 and Q3
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4. 4. Investigate the
operation of radio
receiver.
• Draw a block diagram of an AM tuned radio
frequency receiver and explain its operation
(P4.1, M4.1, D4.1)
• Explain the principle of operation of the
super-heterodyne receiver (P4.2, M4.2, D4.2).
• Describe the necessary arrangements for
transceiver operation (P4.3, M4.3, D4.3).
Q4
3. Grading Criteria of this coursework (overall)
Pass Merit Distinction
a. All outcomes and
associated assessment
criteria have been met.
b. Reasonable concepts on
the subject covered by the
questions in the
coursework have been
demonstrated.
c. TCA (in the form of
Examination) has been
passed.
a. Pass requirement achieved.
b. Substantial concepts on the
subject matter covered by the
questions in the coursework have
been demonstrated.
c. Strategies to find appropriate
solutions to solve the problems in
the coursework have been
identified and applied.
d. Appropriate techniques such as
suitable decision making
statements, looping techniques,
have been selected and applied.
e. Appropriate findings have been
presented in the form of comments
in the main programming code and
also in the documentation section.
a. Pass and Merit Requirement achieved
and
b. First-rate concept of the subject
matter covered by the questions in the
coursework have been demonstrated.
c. Critical reflection to evaluate own
work and justify valid conclusions on the
basis of the results obtained in the case
of each of the problems in the
coursework is evident.
d. Autonomy/ independence in the form
of applying various programming
concepts in solving the problems in the
coursework has been demonstrated.
e. Creative thinking in the form of
applying innovative programming
approaches, analyzing and comparing
various approaches the results are
demonstrated.
4. Question related specific guidelines for Pass/Merit/Distinction
Pass
(P1, P2, P3, P4)
Merit
(M1, M2, M3, M4)
Distinction
(D1, D2, D3, D4)
Question (1) Answering questions
(a) and (d) well. Part
(c) should be
attempted where
student shows
awareness of legal
documentation
(particularly in the
channel allocation
Display a working
knowledge of analytical
techniques in radio
communication. Parts (a),
and (d) should be met with
good critique and level of
understanding – meeting
pass criteria. Part (b)
should be completed
Meeting the merit criteria and
doing creative analysis in the
case of Part (d). The student
must display analytic
knowledge of two ray
channels for Part (c) and
show understanding of legal
requirements beyond just
information gathering.
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5. part). It is highly
important; in order for
a Pass to be
awarded that Part (a)
and Part (d)
demonstrate
understanding and
technical awareness.
Diagrams and some
level of analysis are
highly important. In
Part (a), it is
expected student see
ground wave, sky
wave, and LOS
(Optical and Radio
horizon) as likely
candidates. Part (d)
should be creative
and original, copied
work or inappropriate
diagrams will be
referred to be
redone.
satisfactorily to meet Merit
criteria
Referencing must comply
with Harvard standards
and include peer reviewed
technical publications.
Industrial reports and
Technical standards (IEEE,
ITU, 3GPP) are accepted
but websites, Lecture
Notes etc are not
permitted.
Question (2) Clearly answering all
parts of the questions
to meet a Pass.
Student must at least
demonstrate basic
understanding of AM
and FM for this to
meet Pass criteria.
Meeting the pass criteria
and possessing the ability
to clearly outline the
differences of amplitude
and angle modulation (FM
and PM).
Referencing must comply
with Harvard standards
and include peer reviewed
technical publications.
Industrial reports and
Technical standards (IEEE,
ITU, 3GPP) are accepted
but websites, Lecture
Notes etc are not permitted
Meeting the Merit criteria and
answering the question (b)
very well highlighting the role
of Phase shifter and
balanced modulators.
Analysis involving Hilbert
transform is necessary to get
Distinction,
Question (3) Drawing a clear
diagram of the AM
and FM modulated
transmitter and
explaining the
function of each
components. Part
(a) and Part (b) both
need reasonable
discussions and
justifications to
achieve pass. A
block diagram alone
with minimal
explanation will
cause assignment to
be referred for
resubmission.
Meeting the pass criteria
and describing the
significance of each of the
components and include
examples where possible.
Referencing must comply
with Harvard standards
and include peer reviewed
technical publications.
Industrial reports and
Technical standards (IEEE,
ITU, 3GPP) are accepted
but websites, Lecture
Notes etc are not permitted
Meeting the merit criteria and
doing creative analysis of
each of the components.
Include comparisons and
draw conclusions wherever
possible. To meet the
Distinction criteria, student
must demonstrate enough
knowledge to attempt Part (c)
to a good level.
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6. Question (4) Drawing a clear
diagram of a
superheterodyne
receiver and TRF
receiver for Part (a)
with reasonable
attempt at discussion
for this part of
assignment to be
considered for a
Pass.
Meeting pass criteria and
describing the significance
of each of the components
and include examples
where possible in Part (a).
A good attempt with
creative analysis and
discussion will be expected
in Part (c) in order to
achieve Merit.
Referencing must comply
with Harvard standards
and include peer reviewed
technical publications.
Industrial reports and
Technical standards (IEEE,
ITU, 3GPP) are accepted
but websites, Lecture
Notes etc are not permitted
Meeting the merit criteria and
doing creative analysis of the
function of each of the
components in Part (a) and
(c). A detailed critique and
analysis for Part (b) is
expected for student to
achieve Distinction.
5. Preparation guidelines of the Coursework Document
a. All coursework must be word processed.
b. Document margins must not be more than 2.54 cm (1 inch) or less than 1.9cm (3/4 inch).
c. Font size must be within the range of 10 point to 14 point including the headings and body text.
d. Standard and commonly used type face such as Times new Roman or Arial etc should be used.
e. All figures, graphs and tables must be numbered.
f. Material taken from external sources must be properly refereed using a standard method
g. Word limit must be strictly followed.
6. Plagiarism
Any act of plagiarism will be seriously dealt with according to the regulations. In this context the definition
and scope of plagiarism are presented below:
Plagiarism is presenting somebody else’s work as your own. It includes copying information directly from
the Web or books without referencing the material; submitting joint coursework as an individual effort;
copying another student’s coursework; stealing coursework from another student and submitting it as your
own work. Suspected plagiarism will be investigated and if found to have occurred will be dealt with
according to the college procedure. (For details on Plagiarism please see the student hand book)
7. Submission
a. All coursework must be submitted to the assigned person (to the Tutor) and a receipt must be obtained.
Under no circumstances other College staff accepts them.
b. The copy of the coursework submitted will not be returned to you after marking
c. Any computer files generated such as program code (software), graphic files that form part of the
coursework must be submitted on a floppy disc or CD together with the documentation.
d. The student must attach a copy of the question in between the cover page and the answer.
8. Good practice
a. Make backup of your work in different media (hard disk, floppy disk, memory stick etc) to avoid distress
for loss or damage of your original copy.
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7. b. Make an extra hardcopy of your work submitted for your own reference or later use
9. Extension and Late Submission
a. If you need an extension for a valid reason, you must request one using a coursework extension request
form available from the college. Please note that the lecturers do not have the authority to extend the
coursework deadlines and therefore do not ask them to award a coursework extension. The completed form
must be accompanied by evidence such as a medical certificate in the event of you being sick.
b. Late submission will be accepted and marked according to the college procedure. It is noted that late
submission may result in lower grade or rejection.
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