Patents Assigned to Rabbit Systems, Inc.
  • Patent number: 4991145
    Abstract: A detector and alarm is provided for monitoring air pressure variations in a monitored space, which variations correspond to an intrusion. An infra-sonic detector includes a microphone or the like and a low pass filter to retain only low frequency infra-sonic signals or a bandpass filter to retain a particular range of frequencies between approximately 5 Hz and 12 Hz. The instantaneous infra-sonic signals are compared against a variable reference signal, which is a voltage lagging or delayed variant of the instantaneous signals. In this manner the detector is self adjusting for slow variations in the instantaneous signals but responds immediately to rapid variations to trigger an alarm. In one embodiment the detector only senses negative going air pressure changes to trigger an alarm in order to minimize the incidence of false alarms.
    Type: Grant
    Filed: June 2, 1989
    Date of Patent: February 5, 1991
    Assignee: Rabbit Systems, Inc.
    Inventors: Steven G. Goldstein, James E. Randall, Joseph A. Dattilo, Gary E. Vanyek
  • Patent number: 4890265
    Abstract: A detector and alarm is provided for monitoring air pressure variations in a monitored space, which variations correspond to an intrusion. An infra-sonic detector includes a microphone or the like and a low pass filter to retain only low frequency infra-sonic signals. The instantaneous infra-sonic signals are compared against a variable reference signal, which is a voltage lagging or delayed variant of the instantaneous signals. In this manner the detector is self adjusting for slow variations in the instantaneous signals but responds immediately to rapid variations to trigger an alarm.
    Type: Grant
    Filed: August 3, 1988
    Date of Patent: December 26, 1989
    Assignee: Rabbit Systems, Inc.
    Inventor: Steven G. Goldstein