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S2 Mic Questions — Parallax Forums

S2 Mic Questions

william chanwilliam chan Posts: 1,326
edited 2011-04-05 09:47 in Robotics
Hi,

1. Why S2 Mic uses a pre-amp whereas the Prop Demo Board does not need a pre-amp?
Does this mean the the S2's microphone is more sensitive than the demo board's mic?

2. What does "envelop detector" mean?
Does it mean that it can detect the loudness of a sound?

3. Can the Propeller on the S2 be made to perform a "software low pass filter" to only measure the loudness of low frequencies like 100Hz and below?

Comments

  • Phil Pilgrim (PhiPi)Phil Pilgrim (PhiPi) Posts: 23,514
    edited 2011-04-05 09:47
    1. The pre-amp is on the back PCB with the mic in order to provide a lower-impedance signal source that can drive the cable to the main PCB. Without it, the weak microphone signal might get clobbered with electrical noise on its way to the other PCB. The pre-amp also provides some analog filtering.

    2. The envelope detector program can detect the loudness of a sound.

    3. Using FIR or IIR filters in PASM, the Propeller is capable of low-pass filtering an audio source.

    BTW, the microphone is useful only when the motors are not running, due to the audible whine and gearbox noise they produce.

    -Phil
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