3809067 is referenced by 12 patents and cites 5 patents.

An anti-evasion system is disclosed for breath alcohol testers including a sound transducer and filter network that distinguishes between the presence and absence of human modulation of the breath sample (such as humming) and prevents a gas sample not obtained in conjunction with such modulation from indicating a 'pass'.

Title
Modulation responsive anti-evasion system for breath testers
Application Number
05/260,603
Publication Number
3809067
Application Date
June 7, 1972
Publication Date
May 7, 1974
Inventor
Hoppesch Joseph P
Agent
Banner Donald W
Assignee
Borg Warner Corporation
IPC
A61b 05/00
A61B 05/18
A61B 05/16
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