EE567-Project2

EE567-Project2 - EE 567 Matlab Project#2 Due Date Wednesday...

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EE 567 Matlab Project #2 Due Date: Wednesday, November 18 @ 5:00p in Box #9 near EEB 104 Problem: In this project, you will build onto the digital communication system in Project 1. In the first part, you will investigate the effect frequency offset on BER at various SNRs. You will generate results for BPSK waveform. Again, the symbol rate T s = 1 Hz, so one symbol per second. The sampling rate (fs) is 8 times the symbol rate and use SQRC filters. The main tasks for this assignment are: PART1: (1) For perfect timing, you will add a frequency offset to the received signal and determine performance in the presence of AWGN for SNR values of 20, 10, 5, 0 dB. The idea is to sweep the frequency range from 0 to f MAX which is the frequency at which BER is at or near 50%. Perform this task in small frequency increments and plot the BER versus frequency offset. You should have a single plot with four curves, one for each E b /N 0 . PART2: (1) In this part you will investigate the effect of an power amplifier on the signal quality. You will run your signals through a 900 MHz power amplifier from Maxim (the specification is included). Assume that the amplifier is used just before the receiver filter in your simulation setup for project 1. You will note that in the spec is a curve that describes output power versus input power. There are three curves for different temperatures. Use the 25 °C curve. For this task, you will perform the following: a. Derive an equation that describes the P in -P out relationship in dBm. You should use a third-order polynomial for this task over the range [-20, 5] dBm on the input. b. Generate a noise-free BPSK signal and run it through the power amplifier for the specified drive levels. You may consider saturation to be at 0 dBm. Then, you need to generate signals at -10, 0, 3, 5 and 10 dB IBO. IBO stands for input back-off and describes the drive level relative to saturation. Thus 3 dB IBO means the average input power is -3 dBm. Also, note that -10 dB IBO stands for +10 dBm average input power. c. For the specified power levels, plot the power spectral density for each. There must be one figure per page. Note the number of bits may be small for this task since there is no noise. You probably need only 1000-2000 to ensure all symbol sequences are seen. (2) You will quantify the SNR penalty resulting from the nonlinearity of the amplifier on a BPSK signal. Using the model you have developed for the amplifier in (1), send the output of the amplifier to the receiver filter and perform the regular detection BER simulation to find BER vs. E b N o .
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a. For the given five IBO levels generate the BER vs. E b N o curves for 50,000 bits. You should have a single plot with five curves, one for each IBO, along with the theoretical BER curve (sixth) for comparison. b. What’s the SNR penalty for each IBO at a BER of 10 -3 ? Comment on your results.
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This note was uploaded on 09/26/2011 for the course EE 567 taught by Professor Weber during the Fall '07 term at USC.

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EE567-Project2 - EE 567 Matlab Project#2 Due Date Wednesday...

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