We are working on a project which involves in capturing signals traveling through a rail line. Unfortunately in our country, we have lots of joint in between rail tracks. So the signal gets attenuated and becomes very hard to capture using normal devices like microphones and accelerometers. Could anyone please tell us of good (actually very good) sound capturing devices?
Electronic – Ultra High sensitive sound capturing sensors
microphonesensorsound
Related Solutions
A Piezoelectric sensor is enough for the detection of a kick.
http://en.wikipedia.org/wiki/Piezoelectric_sensor
They are cheap, easy to attach to a shoe and you can even use it as a buzzer to produce the sound.
This simple circuit will help you:
http://www.discovercircuits.com/DJ-Circuits/motionalarm2.htm
You can use a capacitive touch sensor for this sort of thing -- no pressing of any buttons is required.
You need to create 3 things for this to work:
- A sensor PCB which has two metal pads. Mount this inside each of your wooden pieces near the surface. When the user's finger gets close enough, it changes the capacitance between the pads. See this application note for some tips on how to design the sensor.
- A sensor IC wired to these two metal pads which senses the changes in capacitance. Something like the AD7147 could work as the measurement chip.
- A controller of some sort to communicate with the sensor IC and light up the appropriate LEDs.
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Best Answer
If the sound isn't there you can't capture it. Any microphone can be made as sensitive as you want with amplification. What you are really asking for is good signal to noise ratio, not sensitivity.
Look for small microphones that can be attached directly to the track and otherwise have a low inherent noise floor. For good signal to noise ratio, the analog amplifying circuit becomes important too. You want to carefully filter any power supply going near this circuit, shield it from capacitively picking up other signals, filter out RF to keep the frequencies to the range the electronics can handle as intended, use guard traces, etc. Be extra extra careful in the first amplification stage, which will probably have a voltage gain of around 30. After that, the signal will be higher level and lower impedance, and much less susceptible to noise.
As for the best microphone, I'm not up on which technologies inherently provide the best signal to noise ratio. Look thru some datasheets and possibly build a few with circuits to measure the noise floor.
Look carefully at the frequency spectrum of your expected signal. There might be opportunity to filter out large ranges of what the microphone can pick up, thereby eliminating up front noise with that out of band frequency content.