辅导案例-2A

  • May 15, 2020

EGB342-Telecommunications and Signal ProcessingAssignment 2A (20%)Released: Friday, 30th AugustDue: Sunday 22nd September, 11:59pm (Week 9)Individual AssignmentYour previous FM radio design has been a great success, servicing the needs of the entire island.Natalie was very pleased. Fraser island residents have additionally identified the need to beable to communicate this important emergency information back to the mainland. A cablewas laid along the sea floor, providing a means for this communication to occur. After thiscable was laid a number of engineers performed final tests on the communications channel, andfound out that the assumption of an ideal channel is not true. Signals received at both ends areattenuated and noisy. It is important that you implement appropriate receivers to overcomethis noise, so that vital information can be communicated to and from the mainland.Figure 1: Cable Landing at Tuman Bay, Philippines. [Ref: www.wired.com]The aim of this task is to gain an understanding of baseband modulation and matched filtersin digital communication. In particular, the detection of transmitted symbols at the receiver,and the process of transmitter-receiver synchronisation. This consists of two parts. In Part 1,you will modulate a given message using baseband signalling, to be transmitted to mainland.You will implement and demonstrate the operation of matched filtering for symbol detection.In Part 2, you will use a matched filter to synchronise the signal and detect a message with anunknown synchronisation offset.This is an individual task. All students must submit individual and original work. De-tailed instructions on report format and submission guidelines are provided at the end of thisdocument. All solutions must be implemented in MATLAB unless instructed otherwise.*Reminder* Read the entire document before attempting the questions1Work-space PreparationDownload the following files to be used in Assignment 2A from Blackboard and place theminto one working directory.1. Matlab script EGB342 A2A Template.m2. Matlab script GenerateAssignment2AData.m3. Matlab protected script DataGen.pOpen GenerateAssignment2AData.m with MATLAB and read its instructions. Insert yourstudent number into the script and generate your signals for this assignment. [Note: KeepEbN0 = 7 dB for now. You will change this in value in Part 2.7.]. The generated data willbe stored inside the file ‘A2AData.mat’. Contents of the A2AData.mat file will not be requireduntil Part 2.Part 1 – Testing the performance of the cableThe aim in Part 1 of the assignment is to gain an understanding into the baseband modulationand the use of matched filters to detect symbols in the presence of noise. The signal parametershave been selected based on the data rate and the power requirements for the transmission.Binary antipodal signalling will be used to transmit data. The following equation describes thesignal shape that has been selected for the initial testing of the cable.S1(t) ={A(1− |t|/t0) V, |t| < t00 otherwise(1)where t0 = 500 ns and A = 2.5. Assume that the waveform S1(t) represents the binary digit‘1’ and that binary digit ‘0’ is represented by waveform S0(t) = −S1(t).1. Derive and plot the magnitude spectrum of the above pulse shape. (Hint: Use theconvolutional property of the Fourier Transform of a rectangular function to find themagnitude spectrum of the above pulse.)2. Calculate the average energy of the modulation schemes that utilises this pulse shape.3. Draw a diagram to show the transmitted waveform for input bit sequence, [0, 1, 1, 0].4. Create the signal waveforms S1 = S1(t) and S0 = S0(t), representing digit ‘1’ and digit‘0’ respectively. Use 100 data points (NumPts) for each symbol, and plot these signals.Both axes must have appropriate units and must be clearly labelled.1.5 Find the average energy of the modulation scheme using the S1 and S0 generated aboveand compare with the theoretical value calculated in Part 1.2. Comment on the observa-tions.1.6 Write a MATLAB code to modulate your name and ID number (e.g. ‘First Name MiddleName Surname 1234567’) to be transmitted to the mainland using the above modulationscheme. Consider this as your initial test message. Use the 7-bit ASCII table given atthe end of this document to convert text to binary data. [useful MATLAB functions:double, de2bi, reshape.]21.7 Plot the spectrum of the baseband modulated signal generated in Part 1.6, and findthe null-to-null bandwidth required to transmit the emergency text messages. Comparethis spectrum with the theoretical spectrum calculated in Part 1.1 and comment on theobservations. Comment of the bandwidth required to transmit speech signals (digital).1.8 The given message signal need to be transmitted to two separate locations on mainland.Location A and B are 15 km and 25 km away from the Fraser Island transmission station.Cable loss is 4 dB/km. Assuming single sided noise power spectral density to be N0 =10−13 W/Hz, calculate signal-to-noise ratio (SNR) at the destinations. SNR can becalculated using the following expression -SNRdB =(EbN0)dB+ 10 log10(2)− 10 log10(NumPts) (2)where EbN0is the energy-per-bit to noise-density ratio, and NumPts is the number ofsamples per symbol.1.9 Generate and plot these noisy signals received at locations A and B and comment onyour results. Note that if the total cable loss is L, the signal power at the receiver can becalculated using -PRx =PTxLor PRx(dBW ) = PTx(dBW )− L(dB)where PTx and PRx are transmitted and received power respectively.1.10 Illustrate and describe the block diagram for the detection of antipodal binary data us-ing the matched filter implementation. Your diagram can be hand drawn, or computergenerated. How can the transmitted symbol be determined based on the matched filteroutput? Why is it important to know the starting location of the first symbol?This diagram must be done by you, and not cut-and-pasted.1.11 Create and plot the impulse response hopt(t) of the optimum receiver filter matched todetect symbol S1. Describe how you can detect both S1 and S0 using the single matchedfilter matched to S1.1.12 Filter the clean and noisy messages generated in Part 1.4 using the filter() commandand the impulse response of the matched filter, hopt(t), to find the filtered signals.1.13 Plot and compare the three filtered messages. Comment on the similarities and differencesof the matched filter output for the clean and noisy input signals.1.14 Decode the output and display the received text messages. Estimate the number of biterrors and the bit-error probability in each case. Comment on the output for the cleanand noisy received signals. [Useful MATLAB functions: char, bi2de, reshape.]1.15 Compare the bandwidth of the given pulse shape with that of standard pulse shapes(Rectangular, Nyquist, Raised Cosine) and comment on the observations. [Hint: Referto Nyquist criterion for zero inter symbol interference.]3Part 2 – Decoding emergency messages at the receiverYou are now ready to tackle the main task. You are required to detect a message, based on anoisy received signal which is provided to you.Upon receiving a signal, the receiver does not know where the transmitted symbol sequencebegins, thus a preamble is inserted prior to the symbol sequence. The preamble can be regardedas a specific long symbol of shape and duration known to both the transmitter and receiver.Once the receiver detects this preamble, it then knows that the unknown transmitted sequencewill follow.An optimum receiver filter, matched to the known preamble, can be used to detect thepreamble in a similar manner to detecting the particular symbol that follows the preamble.Each student has been given a different preamble based on their student number. The preambleand its corresponding time vector are stored in variables preamble and t preamble respectively.Variables called ‘rx’ and ‘t signal’ would also be loaded into your workspace upon loadingA2AData.mat. These are the noise-corrupted message and its corresponding time domain vec-tor, respectively.Check that you still have these in your workspace, and reload A2AData.mat if necessary.A 7-bit ASCII character is represented in binary, using the bit symbols S1 and S0. Thesymbol definitions are the same as in Part 1. The transmitted ASCII can be any of the 94printable characters. A preamble has been inserted prior to the 7 bits for synchronisation. Thedata has gone through an Additive White Gaussian Noise (AWGN) channel with a randomdelay.The received signal has the following structure, and is corrupted by noise:Random DelayPreamble(1000)7-bit symbols(variable length)Trailing Space(variable length)2.1 Find the impulse response hpre(t) of the optimum receiver filter to detect your preamble.Plot your preamble and hpre(t).2.2 Identify, and state, the start of the message symbol stream using the matched filter for thepreamble hpre(t). Remove the preamble and random delay from the start of the receivedsignal to leave only the message. These tasks are to be performed using MATLAB. Plotthe signal representing the noisy message sequence.2.3 Design the impulse response(s) needed for the matched filter. Filter the received signalrx using the filter() command. Plot the output.42.4 Implement a function (MF receiver) for the matched filter receiver. The function headeris to conform to the following syntax.[recovered data] = MF receiver(noisy message, NumPts, h opt)The (MF receiver) function should perform the following operations.(a) Pass the noisy received signal through the matched filter and record the output.(b) Sample the output of the matched filter every symbol period. Keep in mind thateach symbol is NumPts data points long.(c) Determine the sequence of binary ‘1’ and binary ‘0’ (recovered data) estimatedfrom the sampled matched filter output.2.5 Pass the received signal, rx, through the MF receiver and decode the output and displaythe text message.2.6 Can you decode the message correctly? This message was created assuming an Eb/N0 of 7dB. Describe two methods that you can employ to reduce the bit errors at the destination.2.7 Record the received messages when the Eb/N0 = 0 dB and Eb/N0 = 10 dB respectively andcomment on the observations. You can do this by running the GenerateAssignmen2AData.mfile with different EbN0 [Change the Eb/N0 value on line 25] values and generating a newA2AData.mat file for each Eb/N0.Important: Answers to all the questions should be clearly recorded in the report. If yousubmit only a MATLAB code without a report you will get a fail grade.5ASCII Table010 000032 space010 000133 !010 001034 ”010 001135 #010 010036 $010 010137 %010 011038 &010 011139 ’010 100040 (010 100141 )010 101042 *010 101143 +010 110044 ,010 110145 -010 111046 .010 111147 /011 000048 0011 000149 1011 001050 2011 001151 3011 010052 4011 010153 5011 011054 6011 011155 7011 100056 8011 100157 9011 101058 :011 101159 ;011 110060 ¡011 110161 =011 111062 ¿011 111163 ?100 000064 @100 000165 A100 001066 B100 001167 C100 010068 D100 010169 E100 011070 F100 011171 G100 100072 H100 100173 I100 101074 J100 101175 K100 110076 L100 110177 M100 111078 N100 111179 O101 000080 P101 000181 Q101 001082 R101 001183 S101 010084 T101 010185 U101 011086 V101 011187 W101 100088 X101 100189 Y101 101090 Z101 101191 [101 110092 \101 110193 ]101 111094 ˆ101 111195110 000096 ‘110 000197 a110 001098 b110 001199 c110 0100100 d110 0101101 e110 0110102 f110 0111103 g110 1000104 h110 1001105 i110 1010106 j110 1011107 k110 1100108 l110 1101109 m110 1110110 n110 1111111 o111 0000112 p111 0001113 q111 0010114 r111 0011115 s111 0100116 t111 0101117 u111 0110118 v111 0111119 w111 1000120 x111 1001121 y111 1010122 z111 1011123 {111 1100124 —111 1101125 }111 1110126 ˜6Reflection (Mandatory)A reflection is to be written and appended to the end of your report. Include a short discussion(150 to 200 words) that addresses problems encountered, and things that you would have donedifferently. Identify what concepts this assignment has reinforced, and areas where you canimprove. This section is mandatory and the assignment is regarded as incomplete if absent.Academic Integrity Declaration (Mandatory)Each student must complete the ‘Academic Integrity Declaration’ online form using the pro-vided link on Blackboard. Marks will be withheld if this is not completed, or if thedeclaration is not agreed to.Interview (Mandatory if requested)Interviews will take place (at the discretion of the teaching team) to assess the conceptualunderstanding. This will be a casual discussion. These interviews are compulsory and gradesare withheld until they are completed. Marks may be deducted for poor demonstration ofcontent/assignment knowledge. These interviews will only be for selected individuals, and youwill be notified if you need to take part in an interview.Presentation StandardsThis assignment includes elements of written and coding assessment. You are expected to workindividually. Each student is expected to generate and submit one assignment report and oneset of MATLAB code. Marks are based on how easily and effectively ideas are articulated tothe reader.The teaching team has put together some things to consider -The Report ComponentAn outstanding report demonstrates knowledge and understanding of the subject area. Itcommunicates ideas clearly and logically with a combination of visual, mathematical and codeassets. It demonstrates insight about the underlying concepts and their implications withintelecommunications and signal analysis. Verbose responses, or correct information not articu-lated clearly, will attract deductions.Remember that you are writing to inform.Mathematical working shows a logical procedure (or justification) for the final solutions i.e. Allnon-trivial steps are included. It can be typed or handwritten but must be legible and easilyfollowed.Code snippets used in-text should only contain relevant lines of code and should rarely havemore than five lines in a snippet.7Present the report so that it can be understood without reference to the assignment brief. Anyfigures or code referenced within the code should be no more than one page turn away. Avoidthe use of “see appendix” and “refer to .m file”. Document flow and coherence is to be priori-tised. Reports that are difficult to navigate are marked poorly in this criteria.Write the report assuming that the reader only knows concepts from 1st yearengineering and does not have access to your .m file/s.Include a title page that states the unit name, unit code, assignment number, your name andstudent number. Do not include a table of contents, list of figures, nor a list oftables. Convert the report to the PDF file format before submission. This ensures documenttypesetting is preserved across different computers running different operating systems.The Code ComponentThe submitted code needs to be executable (in MATLAB R2016b or later) and without run-time error. If an error is encountered at execution, your assignment will only be marked untilthe error. No error correction will be made to make your code ‘run’. Coding for this assignmentshould remain within one (provided) file (unless otherwise explicitly instructed). Only includea separate .m file if absolutely necessary.Code should be fully commented to describe intent. Comments should contain enough informa-tion to understand the process without referring to the report. Quality comments encapsulateyour understanding of the topic.* You may use the code provided in the weekly tutorials to check your solutions, however youare expected to generate your own code for your assignment. Submitting supplied .p code asyour own work constitutes academic misconduct and will be considered a run-time error. *8Submission ChecklistSubmission deadline is on the Sunday 22nd September 2019, 11:59 pm. This will be ahard deadline and late submission penalties will apply. As per QUT policy, late assignmentsreceive 0 marks. The report, in PDF format, submitted to Turnitin via the Blackboard link A .zip file, submitted directly to QUT Blackboard via the provided link, that contains -• EGB342 A2A Template.m with your name and ID• A2AData.mat [Generated for Eb/N0 = 7dB]• Functions that are written as a result of explicit assignment instruction• Any other MATLAB scripts you have developed Submissions have been re-downloaded from submission portals and run as-is to confirmsuccessful upload. Online Academic Integrity Declaration from is completed.Submission FAQ⇒ You do not need to assign your submission with a special name. Blackboard assignsunique IDs to all submissions. The submission link is accessible through:EGB342 19se2 → Assessment → Assignment 2A → Assignment 2A: Submis-sion.⇒ You may submit as many times as you like before the deadline. New submissions overwriteold submissions. Only the latest submission is recorded and marked. Upload in-progressversions so there is something to mark if your final submission is late.⇒ All documents can be reviewed after submission and thus it is your responsibility to verifythat the uploaded documents are not corrupt. Corrupt files are treated as incompleteassignments.⇒ Be aware that the electronic time stamp is placed only after all files have uploaded.Blackboard may experience high traffic or your connection may fail unexpectedly. Beginyour final upload at least an hour before the deadline.HardshipIf you experience a hardship which affects your ability to complete, or contribute to, thisassignment, please contact the teaching team as soon as it occurs.QUT also offers counselling services if required.9EGB342 Assignment 2A: Individual Criteria Standards 7+ 7 6 5 4 3 2/1 CR1 - 50% weighting Theoretical understanding Key Milestones - Baseband modulation - Noise and attenuation - Signal detection using Matched Filters - Spectral Analysis - Symbol Synchronisation Demonstrates understanding of the mathematical concepts underpinning this assignment beyond the expected ‘7’ level. Explanations and justifications are unambiguous, accurate and logical. Graphical and mathematical tools are used masterfully to convey knowledge of all topics. Uses appropriate terminology. Has no conceptual errors, but one minor technical/numerical error may exist. Discusses all required concepts and shows evidence of further research. Demonstrates in-depth understanding of the fundamental concepts in this assignment. Explanations and justifications are generally clear, accurate and logical. Graphical and mathematical tools are used fittingly to convey knowledge of all topics. Uses appropriate terminology. Has no conceptual errors, but one minor technical/numerical error may exist. Discusses all required concepts. Demonstrates strong understanding of the fundamental concepts in this assignment. Explanations and justifications are generally accurate and logical. Graphical and mathematical tools are used satisfactorily to convey knowledge of all topics. Uses appropriate terminology. Has no conceptual errors, but minor technical/numerical errors exist. Discusses all required concepts. Demonstrates sound understanding of the fundamental concepts in this assignment. Explanations and justifications are generally accurate and logical. Graphical and mathematical tools are used satisfactorily to convey knowledge of most topics. Uses appropriate key terminology. One minor conceptual error and no more than two technical/numerical errors may exist. Discusses all key concepts. Demonstrates rudimentary understanding of the fundamental concepts in this assignment. Explanations and justifications are generally accurate and logical but are sometimes unclear. Graphical and mathematical tools are used adequately to convey knowledge of most topics. Uses appropriate key terminology. Only minor conceptual, technical or numerical errors exist. Discusses most key concepts. Conceptual understanding is not demonstrated explicitly OR Major conceptual error OR Discussion does not demonstrate understanding of the expected ‘4’ level. Incorrect interpretation/s of underlying concepts i.e. Multiple major conceptual errors. Does not recognise basic errors when discussing generated diagrams. CR2 - 20% weighting Effective written communication Key Milestones - Informative - Easy to read - Clearly explained core ideas - Reflection demonstrates intended learning outcomes Professional format, insightful, core technical ideas are clearly, accurately and succinctly conveyed. The report is very easy to read, and has been written to inform. Only relevant code included in snippets. Figures demonstrate intended point excellently. Referencing is present, and has been done correctly (IEEE). Reflection shows all learning outcomes were reached. Professional format, core technical ideas are clearly and accurately conveyed. The report is easy to read, and has been written to inform. Mostly relevant code included in snippets. Figures demonstrate intended point very well. Reflection shows all learning outcomes were reached. Professional format, technical ideas are clearly conveyed, one minor inaccuracy. The report is informative and easy to read. Mostly relevant code included in snippets. Figures demonstrate intended point well. Reflection shows most learning outcomes were reached. Report format is adequate but missing some coherence in its structure. The report is difficult to read in one or two sections. Consistently irrelevant code included in snippets. Figures demonstrate intended point satisfactorily. Reflection shows some learning outcomes were reached. Report format is missing several critical explanations. The report is difficult to read in several parts. Large amounts of irrelevant code included. Figures demonstrate intended points adequately. Little evidence of reflective thinking. Report formatting was attempted. Contains little, or vague, discussion and lacks cohesion. Largely a code and figure dump. No evidence of reflective thinking. The report has little or no structure. No evidence of reflective thinking. CR3 - 30% weighting Application using Coding Key Milestones – For a 7 in this criteria, all milestones must be satisfactorily reached; For a 6, most must be satisfactorily reached, and so on. • Correct individual-question outputs as per solution-script options Code appears to give correct outputs if widely-varying solutions are possible • Code is optimised (i.e. makes use of vectorisation where appropriate)• Comments are effectively used to describe the code• No runtime errors• Uses functions that are within the scope of the assignment • Code achieves desired output/s on completionLarge sections of code incomplete OR Multiple runtime errors For moderation of overall marks: At the discretion of the teaching team, your group may be selected to attend an interview if the teaching team require clarification about how the group arrived at their solutions, or how individuals contributed to the overall solution. If selected, you will be notified and given details of the location and time of the interview. Oral interview Demonstrated knowledge is consistent with submitted report and code. No moderation of marks. Demonstrates knowledge noticeably below the standard of the submitted report and code. Individual marks may be moderated down up to 20%. Demonstrates knowledge significantly below the standard of the submitted report and code OR Does not attend interview. Individual marks may be moderated down up to 100%. 1

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