| 摘要 |
A method and apparatus of determining the alcohol content of the breath of a test person comprising, measuring the alcohol content of the breath to produce an alcohol content signal, measuring the change in the alcohol content signal, measuring a flow of the breath of the test person, and indicating the alcohol content using the alcohol content signal only when the change in the signal per unit time is below a preselected change value and the flow is above a preselected flow value and where the flow has not dropped below the predetermined flow value since it first reached the predetermined flow value. The change in the signal is determined by the change in the signal per unit time, times the inverse of the instantaneous value for the signal. When the change in the signal satisfies the requirement, a control signal is fed to an AND gate. When the flow value is reached, a second control signal is supplied to the AND gate through a first flip-flop circuit which is connected to a second flip-flop circuit so that no signal is applied to the AND gate if the flow value has dropped below the preselected flow value after it first reached the preselected flow value.
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