Circuit Lake

Electronic Project and Circuit Collection

Audio Spectrum Analyzer

01/05/2010 Category: Audio, PIC, Project


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. A Digital, real-time Audio Frequency 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 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 in real time. The circuit is based on a dsPIC30F6012A, which is chosen for a feature set which matches the requirements of 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 antialiasing filtering and gain are also used in the analog section of the circuit. The project designed by George Adamidis.

Here is the Project Features:

  • It is a low-cost circuit and can be embedded in any audio device.
  • It uses a simple, low cost 20×20 LED display
  • It supports four display modes (“0-Climbing-Bars”, “1-Bars”, “2-Climbing-Bars+Rain”, “3-Bars+Peaks”)
  • It provides a very good frequency and amplitude resolution (0.431 octaves from 31 to 15000Hz and 1.3 db from 0 to –28db.
  • Can be powered from a single 5V power supply.
  • Offers simultaneous monitoring of the entire audio signal band in real time.
  • Uses a single processor both for DSP and display controlling (there is no need for a separate display controller).

Audio Spectrum Analyzer
Download Project Documentation (zip)