US3828336A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Intrusion alarm system with improved air turbulence compensation
Assignee: MASSA DONALD P COHASSET
•
Filing: 1973-07-12
•
Granted: 1974-08-06
•
Expires: 1993-07-12
Abstract
Abstract This ultrasonic intrusion alarm system responds to the Doppler shift caused by moving intruders. Instantaneous changes in amplitude are detected by peak detectors. The detected signals are filtered to reduce the sensitivity to low frequency air turbulence.
Inventors
- 👤 D Massa
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 06:24
CPC Classifications
G; G08; G08B; G08B13/00; G08B13/16; G08B13/1609; G08B13/1618; G08B13/1627
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
190 words
In an intrusion alarm system, means for radiating a signal at a predetermined frequency into a space, means for receiving the signal as it is reflected from objects within the space, the received signal having a frequency differing from that of the radiated signal by amounts corresponding to the rates of movement of said objects, demodulation means for producing a difference signal having a frequency spectrum corresponding to the differences in the frequencies of the radiateD and received signal, filter means connected for filtering the difference signal and passing only a selected band of frequencies lying within the upper portion of the frequency spectrum of the difference signal, signal processing means connected to the output of said filter, said signal processing means characterized in that its output contains an AC signal corresponding approximately to the envelope of the variation in the peak amplitudes of the AC signal which appears at the output of said filter, a high pass filter connected to the output of said signal processing means, and signal detection means for recognizing the presence of a signal when it appears at the output of said high pass filter.
Claim 2
Dependent Claim
190 words
In an intrusion alarm system, means for radiating a signal at a predetermined frequency into a space, means for receiving the signal as it is reflected from objects within the space, the received signal having a frequency differing from that of the radiated signal by amounts corresponding to the rates of movement of said objects, demodulation means for producing a difference signal having a frequency spectrum corresponding to the differences in the frequencies of the radiateD and received signal, filter means connected for filtering the difference signal and passing only a selected band of frequencies lying within the upper portion of the frequency spectrum of the difference signal, signal processing means connected to the output of said filter, said signal processing means characterized in that its output contains an AC signal corresponding approximately to the envelope of the variation in the peak amplitudes of the AC signal which appears at the output of said filter, a high pass filter connected to the output of said signal processing means, and signal detection means for recognizing the presence of a signal when it appears at the output of said high pass filter.
Claim 3
Dependent Claim
78 words
The invention in claim 1 characterized in that said radiated signal is ultrasonic and said predetermined frequency lies within the approximate range 18 - 50 kHz, said filter means is a band pass filter whose pass band is centered at a frequency which lies within the upper broad peak response range of the moving target Doppler spectrum, said signal processing means includes a peak detector, and said high pass filter has a cut-off frequency greater than 5 Hz.
Claim 4
Dependent Claim
29 words
The invention in claim 2 characterized in that said demodulation means includes means for combining a signal corresponding to the frequency of the radiated signal with the received signal.
Claim 5
Dependent Claim
27 words
The invention in claim 2 characterized in that said high pass filter has a cut-off frequency which lies within the approximate range 10 Hz - 30 Hz.
Claim 6
Dependent Claim
26 words
The invention in claim 2 characterized in that said band pass filter has a pass band centered within the approximate range 20 Hz - 80 Hz.
Claim 7
Dependent Claim
15 words
The invention in claim 2 characterized in that said signal processing means includes an integrator.
Claim 8
Dependent Claim
23 words
The invention in claim 2 and an alarm circuit operated by the output of said signal processing means when an output signal appears.
Claim 9
Dependent Claim
23 words
The invention in claim 6 and an alarm circuit operated by the output of said signal processing means when an output signal appears.
Claim 10
Dependent Claim
137 words
An ultrasonic intruder alarm comprising an ultrasonic signal oscillator, ultrasonic transmitting transducer means capable of radiating acoustic energy throughout a space to be insonified connected to said oscillator, ultrasonic receiving transducer means capable of receiving said radiated energy as it reflects from objects within the insonified space, an amplifier connected to said receiving transducer means, demodulation means, the amplifier output signal connected to said demodulator, the output from said demodulation means connected to a band pass filter, a first peak detector connected to the output of said band pass filter, a high pass filter connected to the output of said first peak detector, a second peak detector connected to the output of said high pass filter and an alarm circuit which is activated by the output signal from said second peak detector whenever an output signal appears.
Claim 11
Dependent Claim
137 words
An ultrasonic intruder alarm comprising an ultrasonic signal oscillator, ultrasonic transmitting transducer means capable of radiating acoustic energy throughout a space to be insonified connected to said oscillator, ultrasonic receiving transducer means capable of receiving said radiated energy as it reflects from objects within the insonified space, an amplifier connected to said receiving transducer means, demodulation means, the amplifier output signal connected to said demodulator, the output from said demodulation means connected to a band pass filter, a first peak detector connected to the output of said band pass filter, a high pass filter connected to the output of said first peak detector, a second peak detector connected to the output of said high pass filter and an alarm circuit which is activated by the output signal from said second peak detector whenever an output signal appears.
Claim 12
Dependent Claim
29 words
The invention in claim 9 characterized in that said demodulation means includes means for combining a signal corresponding to the frequency of the radiated signal with the received signal.
Claim 13
Dependent Claim
36 words
The invention in claim 9 characterized in that an integrator is included in the output circuit of said second peak detector for preventing transient signals from passing from said second peak detector to said alarm circuit.
Claim 14
Dependent Claim
65 words
The invention in claim 9 characterized in that the frequency of the ultrasonic signal generated by said oscillator lies within the approximate range 18 kHz - 50 kHz, said band pass filter is centered at a frequency within the approximate range 20 Hz - 80 Hz, said high pass filter has a cut-off frequency which lies within the approximate range 10 Hz - 30 Hz.
Claim 15
Dependent Claim
36 words
The invention in claim 12 characterized in that an integrator is included in the output circuit of said second peak detector for preventing transient signals from passing from said second peak detector to said alarm circuit.
References Cited (Backward Citations)
US2623931A
Cited
US2767393A
Cited
US2769972A
Cited
US2782405A
Cited
US3383678A
Cited
US3662371A
Cited
US3638210A
Cited
US3665443A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-08-05 | 1978-02-04 | 1978-08-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-08-05 | 1982-02-04 | 1982-08-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-08-05 | 1986-02-04 | 1986-08-06 | $7700.00 | Window Closed / Lapsed |