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Spectrum Analyzer Using FRDM KL25Z
Transcript of Spectrum Analyzer Using FRDM KL25Z
It's hard to quantify the distortion by looking at a good sine wave output from a function generator on an oscilloscope.
Another example is noise analysis. Looking at an amplifier's output noise on an oscilloscope basically measures just the total noise amplitude.
On a spectrum analyzer, the noise as a function of frequency is displayed.
In simple terms, an analog filter was used to isolate frequencies of interests, thereby tuning the filters and repeating the measurements, a reasonable spectrum could be obtained.
ARM Cortex M0+ (KL25Z)
OLED display (128x64) - 3V
Electret microphone - 20Hz – 20KHz, 500mA
Proposed Architecture for
SPECTRUM ANALYZER USING FRDM KL25Z
"An audio spectrum analyzer that displays a real-time histogram-style visualization of the frequency spectrum of an audio input signal on a TV screen."
Task Breakdown with Specific Time Duration
Key Areas !!
Fast Fourier transform
Pradeep Ravindran – 7248881
Karthi Mathialagan - 7190212
Praveen Kumar - 7308078
Nithin Kumar - 7316984
Difficulties we faced
This project aims to measure the amplitude of an input signal (an audio signal) versus frequency.
Data visualization Present information intuitively
Testing data based on sample part.
Codewarrior 10.6v (Eclipse)
IC regulators - 20 Input Vol(max), 4.3V
IC transmitter and receivers - 3.6V, Full duplex
Op-amp - 1.8V, 80mA
Resistors - 2.2k
Potentiometer - 50komhs, 0.5W, +/- 10%
Fast recovery diode - 1.3V, 150ns, 1A
Ceramic capacitors - 0.1µF, 50V
Aluminum capacitors - 220µF, 10V
FAST FOURIER TRANSFORM
PING PONG BUFFERS
Calculates Discrete Fourier transform and its inverse
Breaks the signals into two halves
A linear combination of modulated rectangular window
FFT measurements are subject to errors called leakage.
It usually occurs when FFT is computed from a block of data i.e. not periodic
Hanning windows comparatively has good frequency resolution and spectral leakage.
Most frequently used for random excitations.
Cadence Capture CIS Lite
PCB Editor Lite
PCB fabrication - 120$
SMT components - 78$
Total - 200$ (Approx.)
Graphic drivers ( OLED )
Sampling rate is slower compared to other Cortex boards.
ARM CORTEX MO+
( Codes DSP library to enable Fast Fourier
PCB Editor Lite
Future Scope & Applications
FFT can be replaced with wavelets - Gives higher efficiency
For higher end audio based anomaly measurements of faults in motor and generators.
Military applications - voice recognition
Ping pong Buffers
Few Snaps !!
Technical Knowledge Gained
How to use CMSIS DSP library files of M0+
PCB designing using ORCAD CADENCE
Eli Huges ( Defense & Space Consultant ,
Penn State University )
Mohammad Hossein Askari Hemmat MAsc.
Submitted to- Prof.Otmane Ait Mohamed
Referred articles :
TEXAS INSTRUMENTS SINGLE SUPPLY OPAMP DESIGN
INCIPIENT FAULT DETECTION OF BEARINGS USING WAVELET TRANSFORM TECHNIQUE