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Honored ContributorAppropriate ADC for educational project?
Hello folks!
I'm a student of 'Network Systems and Data Communications' department in Greece and am doing my final project/dissertation right now in Leiria, Portugal at Electrical Engineering department. Because the subject is kind of complex, I'm going to introduce to you only the part on which I'd like to set my specific question. I want to implement a small device/circuit which will be inputted some analog voice commands from a normal electret mic. Till now I'm not clear about what pre-amp/op-amp I should use, but I believe I'll figure this out. The implemented circuit will be interfaced onto a Pluto-II (Cyclone-I) FPGA board, probably SPI/i2c will fit the best. I've read a lot about ADC's appropriate for voice/audio systems, and I suggest that an Σ-Δ (sigma-delta) ADC will be good for me, in combination of a simple low-pass anti-aliasing filter consisting of a resistor and a capacitor in parallel before the ADC. Actually, regarding the Σ-Δ ADC I still have no clear image if it is a linear or logarithmic ADC, cause as far as I know, it should be a logarithmic one for audio sampling, isn't it? Considering a specific topic of your forum and obvious knowledge you people got, I thought that maybe you could suggest to me any appropriate market ADC for my purpose. Thank you! Sincerely, David32 Replies
Altera_ForumTry ADS1202 It works great and is small.
Greetings to Leiria, from a Portuguese living in Germany.- Altera_Forum
Nonlinear coded AD/DA has been used in early days of digital voice processing (e.g. with the µ-law codec), but it's long gone. SD ADC are linear by it's operation principle, also any kind of digital signal processing (e.g. decimation, filtering, FFT) is based on linear coding. If huge dynamic is involved in an application, it may use dynamical gain switching and a respective floating point data representation. But it's surely not required for voice processing. I would assume, that a resolution of 10 or 12 Bit is sufficient for your purpose.
