Download a copy of Lab3 MA FIR.zip from the course shell onto the desktop of your computer
and unzip the project to the desktop. Double click on MA FIR.mcp to open the project with
CodeWarrior, and then load it into the Tower system. Compile, load, and run the program on the
Tower system before proceeding to the next step. This loads and runs the 9-point, moving
average filter using the input ADC and output DAC channels that you have just connected.
With the moving average filter program running on the Tower system, verify that the output shown
on Channel 1 of the oscilloscope is a sine wave and that the frequency is the same as the input
signal from the signal generator.
Open a new Excel spreadsheet, and create a data entry table similar to what is shown in Table 2.
Measure and record the filter output amplitude for the Vin = 2.0 Vpp at 10 Hz. Record this
measurement as the 0 Hz measurement due to filter restraints.
Without changing any other settings, increase the frequency to 50 Hz, and record this
measurement as the 50 Hz measurement.
Increase the frequency by 50 Hz to 100 Hz, measure and record the filter output amplitude for the
Vin = 2.0 Vpp at 100 Hz.

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Repeat the above steps for all frequencies listed in Table 2 increments of 50 Hz up to and
including 1,000 Hz.
9-Point, Moving Average
Filter Frequency Response
Linear
Vin = 2.0 Vpp
Freq (Hz)
Vout (p-p)
Note: 10 Hz used for 0 Hz
0
Measurement
50
100
150
200
250
300
350
400
450
500
550
600
650
700

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750
800
850
900
950
1,000
Table 2: Data Table for Moving Average Filter ResponseCopy and paste your moving average filter response Excel data table into the Week 3 Lab coverreport in the space provided.From the data recorded in the previous steps, create a graph of the 9-point, moving average filterlinear magnitude frequency response, similar to what was shown in Figure 3. Copy and paste thisgraph into the Week 3 Lab cover report. This graph will be used to answer several questions inthe cover report.Please note that because you have just measured a 9-point, moving average filter, that the graphwill be somewhat different than the 7-point, moving average filter shown in Figure 1. However, thefollowing calculations and frequency points are still accurate.The first zero gain (linear) frequency point occurs at 2π/M or F /M, where F is thesampling frequency of the system.The cutoff frequency, where the gain of the filter drops to 0.707 of its DC value, occurs atπ/M or 0.5F /M, again where F is the sampling frequency of the system.Answer the following questions in the Week 3 Lab cover report.Sallen-Key Low-Pass Filter Analysis QuestionsUsing the Vpp output at 1,000 Hz as your reference, and the fact that a second order, low-passfilter attenuates a frequency at the rate of -12 dB per octave, calculate the dB attenuation perdecade for the measurements indicated below.

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- Fall '15
- Digital Signal Processing, Low-pass filter, Finite impulse response, Electronic filter, Digital filter, Lab Overview