A Digital, real-time Audio Spectrum analyzer circuit for audio devices is presented in this project. This circuit aims to professionals or hobbyists who would like to embed it in an audio device or use it as a stand-alone unit. The Digital, real-time Audio Frequency Spectrum Analyzer can display the distribution of the audio signal energy to 20 specific frequency bands, using DSP technology. It uses fast Fourier transform (FFT) in order to monitor the entire audio signal band in real time. The obtained Fourier transform results are being processed by means of a bank of 20 parallel frequency filters and are being displayed in 20 bars on a simple 20 x 20 LED display. The unit supports four display-modes.
Spectrum analyzers are employed in most of the modern signal processing systems for measuring the distribution of signal energy in frequency. An audio spectrum analyzer is used for measurements in the audible frequency spectrum (from 0 to 20000 Hz) and can be a very powerful tool for keeping a studio well tuned. Many modern audio devices, such as amplifiers, audio-equalizers, audio mixers and PC-audio players contain a spectrum analyzer, which is used to display an audio frequency spectrogram (the frequency spectrum of the audio signal) on an LCD, CRT or LED display. The spectrogram not only offers a spectacular visual effect but also provides a quick way to inspect the audio performance during playback, recording or during any tonal adjustment (bass, treble, mid frequencies adjustment or adaptive equalization).
A Digital, real-time Audio Spectrum analyzer circuit for audio devices is presented in this project. This circuit is based on a dsPIC30F6012A, which is chosen for a feature set which matches to the requirements for this project. The DSP engine, the 12-bit A/D converter, the timer3 timer, 42 I/O ports and the large internal data memory of the dsPIC30F6012A are used in this project. A quad of dual MCP6022 op-amps for anti-aliasing filtering and gain are also used in the analog section of the circuit.
Digital signal processing, fast Fourier transform, frequency spectrum, Hamming window, real and complex vectors, frequency response, filter-bank, bar-graph, display frame and frame rate.
The Digital, real-time Audio Spectrum analyzer circuit for audio devices can be connected to any audio device. It accepts an analog audio signal as input. It digitizes and processes this audio signal using a DSP. It computes the distribution of the audio signal energy to 20 specific frequency bands and displays it on a 20×20 LED display. Everything is done in real time. Author: George Adamidis