Difference between revisions of "S14: Spectrum Analyzer for Audio Frequency Signals"
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== Design & Implementation == | == Design & Implementation == | ||
| − | The | + | === Introduction === |
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| + | A Spectrum analyzer is used in measuring the magnitude of an input signal versus a frequency for a certain frequency range of an instrument. The primary use of a Spectrum analyzer is to measure power of spectrum of unknown or known signals. An input signal that a spectrum analyzer measure is electrical, however, signals like acoustic pressure or optical waves can also be measured by use of an appropriate transducer. | ||
| + | |||
| + | By analyzing the spectra of electrical signals, dominant frequency, power, distortion, harmonics, bandwidth, and other spectral components of a signal can be observed that are not easily detectable in time domain waveforms. These parameters are useful in the characterization of electronic devices, such as wireless transmitters. | ||
| + | |||
| + | The display of a spectrum analyzer has frequency on the horizontal axis and the amplitude displayed on the vertical axis. To the casual observer, a spectrum analyzer looks like an oscilloscope and, in fact, some lab instruments can function either as an oscilloscope or a spectrum analyzer. | ||
| + | |||
| + | Spectrum analysis can be used at audio frequencies to analyse the harmonics of an audio signal. A typical application is to measure the distortion of a nominally sinewave signal; a very-low-distortion sinewave is used as the input to equipment under test, and a spectrum analyser can examine the output, which will have added distortion products, and determine the percentage distortion at each harmonic of the fundamental. Such analysers were at one time described as "wave analysers". Analysis can be carried out by a general-purpose digital computer with a sound card selected for suitable performance[11] and appropriate software. Instead of using a low-distortion sinewave, the input can be subtracted from the output, attenuated and phase-corrected, to give only the added distortion and noise, which can be analysed.[12] | ||
| + | |||
| + | An alternative technique, total harmonic distortion measurement, cancels out the fundamental with a notch filter and measures the total remaining signal, which is total harmonic distortion plus noise; it does not give the harmonic-by-harmonic detail of an analyser. | ||
=== Hardware Design === | === Hardware Design === | ||
Discuss your hardware design here. Show detailed schematics, and the interface here | Discuss your hardware design here. Show detailed schematics, and the interface here | ||
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| − | |||
=== Hardware Interface === | === Hardware Interface === | ||
Revision as of 08:12, 22 May 2014
Contents
Grading Criteria
- How well is Software & Hardware Design described?
- How well can this report be used to reproduce this project?
- Code Quality
- Overall Report Quality:
- Software Block Diagrams
- Hardware Block Diagrams
- Schematic Quality
- Quality of technical challenges and solutions adopted.
Spectrum Analyzer for Audio Frequency Signals
Abstract
We plan to build a Spectrum Analyzer for Audio Frequency signals. Our device is able to display frequencies in audio of up to 4 kHz, which covers the most of the of the frequency range of typical music. The main inspiration for our project was applications of Music visualizers which are seen in many softwares like Windows Media Player.
Objectives & Introduction
The main objective of our project was to display the audio input given to the mic through an LED display. The range of frequency was kept to 4K Hz as it covers most of the frequency range for a typical musical instrument. The LED matrix will be able to display change in the audio signal correspondingly.
The scope of the project was divided into 3 main parts :
- ADC interfacing with the audio input through mic.
- Performing FFT calculations on the LPC1758 board and communication of the same to LED matrix.
- Interfacing of the 16 X 32 LED matrix with LPC1758 board
Team Members & Responsibilities
- Anand Dumbre
- ADC interfacing, LED Interfacing
- Chinmay Vaidya
- Fast Fourier Transform calculations, Hardware.
- Kevin Beadle
- LED interfacing
Schedule
Show a simple table or figures that show your scheduled as planned before you started working on the project. Then in another table column, write down the actual schedule so that readers can see the planned vs. actual goals. The point of the schedule is for readers to assess how to pace themselves if they are doing a similar project.
| Week# | Date | Planned Task | Actual Task |
|---|---|---|---|
| 1 | 03/13/14 | Order & receive parts. | Ordered the parts.late by 1 week as parts were not available |
| 2 | 03/20/14 | Interface microphone/LED strip to SJ One board. | Obtained the parts. Started work on Microphone and LED. |
| 3 | 03/27/14 | Design band pass filter to reduce noise. | Done |
| 4 | 04/03/14 | Analyze audio signals with Matlab using FFT. | The waveforms were not coming out properly. FFT code was working alright |
| 5 | 04/10/14 | Write code to process audio signal on SJ One board. | FFT code working fine. |
| 6 | 04/17/14 | Write algorithm to output audio signal to LED strip. | ADC and FFT output coming out properly |
| 7 | 04/24/14 | Test algorithm using different audio sources. | Tested using various Youtube audio. Still working on porting of LED strip. |
| 8 | 05/01/14 | Finalize project firmware. | |
| 9 | 05/08/14 | Finalize project demonstration. | |
| 10 | 05/13/14 | Finalize project report. |
Parts List & Cost
Give a simple list of the cost of your project broken down by components. Do not write long stories here.
| Component Name | Quantity | Cost per Item | Total Cost |
|---|---|---|---|
| Audio Amplifier Board | 1 | 25 | 25 |
| LPC1758 Board | 2 | 70 | 140 |
| LED Matrix (16 X 32) | 1 | 35 | 35 |
| Wires | 50 | 0.5 | 25 |
| 10 | 05/13/14 | Finalize project report. |
Design & Implementation
Introduction
A Spectrum analyzer is used in measuring the magnitude of an input signal versus a frequency for a certain frequency range of an instrument. The primary use of a Spectrum analyzer is to measure power of spectrum of unknown or known signals. An input signal that a spectrum analyzer measure is electrical, however, signals like acoustic pressure or optical waves can also be measured by use of an appropriate transducer.
By analyzing the spectra of electrical signals, dominant frequency, power, distortion, harmonics, bandwidth, and other spectral components of a signal can be observed that are not easily detectable in time domain waveforms. These parameters are useful in the characterization of electronic devices, such as wireless transmitters.
The display of a spectrum analyzer has frequency on the horizontal axis and the amplitude displayed on the vertical axis. To the casual observer, a spectrum analyzer looks like an oscilloscope and, in fact, some lab instruments can function either as an oscilloscope or a spectrum analyzer.
Spectrum analysis can be used at audio frequencies to analyse the harmonics of an audio signal. A typical application is to measure the distortion of a nominally sinewave signal; a very-low-distortion sinewave is used as the input to equipment under test, and a spectrum analyser can examine the output, which will have added distortion products, and determine the percentage distortion at each harmonic of the fundamental. Such analysers were at one time described as "wave analysers". Analysis can be carried out by a general-purpose digital computer with a sound card selected for suitable performance[11] and appropriate software. Instead of using a low-distortion sinewave, the input can be subtracted from the output, attenuated and phase-corrected, to give only the added distortion and noise, which can be analysed.[12]
An alternative technique, total harmonic distortion measurement, cancels out the fundamental with a notch filter and measures the total remaining signal, which is total harmonic distortion plus noise; it does not give the harmonic-by-harmonic detail of an analyser.
Hardware Design
Discuss your hardware design here. Show detailed schematics, and the interface here
Hardware Interface
In this section, you can describe how your hardware communicates, such as which BUSes used. You can discuss your driver implementation here, such that the Software Design section is isolated to talk about high level workings rather than inner working of your project.
Software Design
Show your software design. For example, if you are designing an MP3 Player, show the tasks that you are using, and what they are doing at a high level. Do not show the details of the code. For example, do not show exact code, but you may show psuedocode and fragments of code. Keep in mind that you are showing DESIGN of your software, not the inner workings of it.
Implementation
This section includes implementation, but again, not the details, just the high level. For example, you can list the steps it takes to communicate over a sensor, or the steps needed to write a page of memory onto SPI Flash. You can include sub-sections for each of your component implementation.
Testing & Technical Challenges
Describe the challenges of your project. What advise would you give yourself or someone else if your project can be started from scratch again? Make a smooth transition to testing section and described what it took to test your project.
Include sub-sections that list out a problem and solution, such as:
My Issue #1
The main issue was obtaining correct parts for the audio amplifier board and LED strip. The gain of amplifier needed to correct for required frequency. Also, the parts were not available on Websites. Resolution: checked the forums on the websites to obtain more information about the boards. Placed an order for deliver when available on the Adafruit and Sparkfun.
My Issue #2
We required the timer1 for ADC. However, the timer1 was configured for the I2C bus. Hence, we changed the I2C bus ports to timer2 and used the timer1 for ADC
My Issue #3
Adafruit Led strip had a library for Arduino. We need to port it to LPC in order to get our LED strip working.However, there are timing issues as the clock frequencies are not same for both. Issue is not resolved yet.
Conclusion
Conclude your project here. You can recap your testing and problems. You should address the "so what" part here to indicate what you ultimately learnt from this project. How has this project increased your knowledge?
Project Video
Upload a video of your project and post the link here.
Project Source Code
Send me your zipped source code and I will upload this to SourceForge and link it for you.
References
Acknowledgement
Any acknowledgement that you may wish to provide can be included here.
References Used
List any references used in project.
Appendix
You can list the references you used.
