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Dear Sirs.
We in the Moscow State Mining University elaborated spirometer-volumeter or intellectual sensor for spiroanaliser (bodypletizmograth). The device has unsurpassed characteristics: inertiales (300 or even more samples per second), sensitivity (transforming to velocity–1 sm/second or even less if necessary); dynamic range – up to 1000. The cross section of the breathing channel is completely free (You will see nothing in it). We've demonstrated the device to our medical experts and they evaluated it highly.
We'd like to cooperate with some company producing life supporting or diagnostics apparatus .
Sincerely, prof. S.Shkundin,
head of Electroengineering dept.
Acoustic spirometers
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Device for measuring lung capacity: an instrument for measuring the capacity of the lungs
Figure 1
Two samples of primary sensor laying on the mirror to demonstrate the inside channel free cross section
Figure 2
Four different primary sensors and two different electronics blocks, one of them admitting connection with the computer, another - with its own display.
Figure 3
The breathing process on computer display.
Theoretically calculated transition function of the spirosensor, when the input step of the velocity is applied not directly to the sensor, but to the input of air dynamics tube, in whish it is situated.
Experimental transition process:
Blue – the input signal.
Red – the output signal.
Fig 6 illustrates the error of measurements of breathing volume imitated by metrology syringe hand controlled (unstable regime). One hundred measurements.
Some comments to Your questions:
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The frequency of sampling 300Hz
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The time of one measurement ~ 0,8ms
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The filling frequency 80 MHz
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The error of velocity measurement:
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In the range 0,05M/s 20%
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0,1 M/s 10%
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1M/s 1%
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>1 M/s less then 1%
If the outside temperature changes by 10 degrees centigrade during 10 ms, the error does not change. Just the same with dependence upon the height . As far as all influences of outside conditions affect the sound velocity we give the experimental evaluation: the change of the sound velocity of 10m/s during 1ms causes the error increase- 0,1%.
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