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Topic: Real Time Audio Processing (Read 4064 times) previous topic - next topic

zkhan

#60
Mar 11, 2019, 05:36 am Last Edit: Mar 11, 2019, 05:58 am by zkhan
Thank you! Also, because the audrino has a 16 MHZ processor it limits sampling rate. For example if the MHZ was higher it would increase the sampling rate. Furthermore, avr takes 13 conversion cycles, similarity , if the cycles took less steps you can increase the sampling rate. Is that correct?


Moreover, what other limitations does the audrino have in terms of an audio system as I made. For example, some constraints perhaps?

Grumpy_Mike

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because the audrino has a 16 MHZ processor it limits sampling rate.
The limit on a Uno is because of the maximum speed of the A/D, this is way below what ever limits are imposed by the clock speed. The A/D can be made to go faster with no loss of quality but if it is made to go too fast the sample becomes increasing noisy.

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Furthermore, avr takes 13 conversion cycles, similarity , if the cycles took less steps you can increase the sampling rate. Is that correct?
Yes, the type of A/D converter used is known as a successive approximation type. Other types exists some that use fewer cycles and others that use less. The type known as a flash converter is fastest requiring only one cycle and is used for video but these are expensive and most are restricted to just 8 bits.

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Moreover, what other limitations does the audrino have in terms of an audio system as I made
Lack of RAM limits sample buffer sizes to just fractions of a second.

Happy conclusion - I assume this is for your report.

zkhan

I am asking because maybe another micro controller will be better for this type of job for example like the Arduino Due or the ras pi mcu.

Grumpy_Mike

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example like the Arduino Due or the ras pi mcu.
Due yes, Raspberry Pi no as it is not a real time operating system so doing audio requires I2S drivers and external sound card.

zkhan

Ohh okay. Thank you. I had one quick question, so previously we were talking about the circuit to take the input of the 3.5 analog signal to the audrino. I understand the op amp however i didn't fully understand the purpose of the two resistors and the capacitor. Any help, i believe that in was in the previously page. Thank you.

Grumpy_Mike

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however i didn't fully understand the purpose of the two resistors and the capacitor.
It is to bias the audio signal to the mid point of the D.C. range of the A/D converter in the Arduino.

An audio signal is AC, it has positive and negitave peaks. The Arduino can not handle negitave voltages so you have to bias or shift up the D.C. value to half the supply rail with resistors. Then to stop the output device shorting out this bias you couple into this with a capacitor. This is called AC coupling, but just means connected with a seriese capacitor.

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