Communications: electrical – Condition responsive indicating system – Specific condition
Reexamination Certificate
1999-01-28
2001-03-27
Swann, Glen (Department: 2736)
Communications: electrical
Condition responsive indicating system
Specific condition
C340S554000, C342S021000, C342S028000, C342S160000
Reexamination Certificate
active
06208248
ABSTRACT:
REFERENCES
U.S. Patents Documents
a. U.S. Pat. No. 3,728,632 April 1973 Gerald F. Ross Transmission and Reception System for Generating and Receiving Base-band Pulse Signals Without Distortion
b. U.S. Pat. No. 3,735,395 May 1973 Gerald F. Ross Base-band Short Range Pre-collision Sensor for activation of Vehicle Safety Apparatus
c. U.S. Pat. No. 3,739,392 June 1973 Gerald F. Ross, Kenneth W. Robbins Base-band Radiation and Reception System
d. U.S. Pat. No. 3,772,697 November 1973 Gerald F. Ross Base-band Pulse Object Sensor System
e. U.S. Pat. No. 3,755,696 August 1973 A. M. Nicolson, Robert Brophy Detector Having a Constant False Alarm Rate and Method for Providing Same
f. U.S. Pat. No. 3,858,205 December 1974 Gerald F. Ross Baseband Precollision Sensor with Time-domain Gating for Preventing False Alarms
g. U.S. Pat. No. 3,858,204 December 1974 Kenneth W. Robbins Closed Loop Gain Control Tunnel-Diode Base-band Object Detector
h. U.S. Pat. No. 3,983,422 September 1976 A. M. Nicolson, Richard M. Mara Detector Having a Constant False Alarm Rate
i. U.S. Pat. No. 5,216,695 June 1993 G. F. Ross, R. M. Mara, K. W. Robbins U.S. Pat. No. 5,307,079 (a divisional) Short Pulse Microwave Source with a High PRF and Low Power Drain
Publications
j. C. L. Bennett, G. F. Ross Time Domain Applications and its Applications Invited Paper, Proceedings of the IEEE, Vol. 66, No. 3. pp. 299-318.
k. Edmond Miller, Editor, Time-Domain Measurements in Electromagnetics, Van Nostrand Reinhold, New York, 1986
l. H. Bertoni, L. Carin, L. Felson, Ultra Wide-band Short Pulse Electromagnetics, Plenum Press, New York 1993
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to the field of short-range radar sensors on land and water used to protect assets against unwarranted intruders and terrorists.
2. Description of Prior Art
There is a continual requirement to protect a given perimeter over wide angles from approaching intruders. This is often to protect military assets but also can be used for home and industry as well. Intruders may take the form of walkers or crawlers or runners or even vehicles. For shipboard application, intruders may approach a docked ship in a harbor under a variety of sea state conditions. Sensors currently used to provide perimeter detection employ a narrow microwave beam breaker system similar to a photoelectric device. The microwave beam breaker is subject to high levels of false alarms especially under varying weather conditions; the photoelectric system is, generally, limited in range. Both the photo-electric and microwave beam sensors cannot look beyond, for example, a fence; an alarm is sounded only when the beam barrier is crossed.
Ultrasonic sensors provide an ability to look out beyond the fence or barrier. Their range, however, is limited to less than 100 feet. Some sonic sensors have ranges beyond 100 feet, but cannot resolve multiple targets. Optical cameras, coupled with infrared night-vision and motion-sensing capabilities, can only view narrow azimuths, and are currently very expensive to implement. Radar sensors, as described in references j and k, appear to have the best properties for establishing wide-angle coverage over a perimeter over hundreds of feet in front of a fence or barrier without clutter while establishing a sufficient resolution to detect human and vehicle targets. However they are subject to false detections because of clutter.
In uncluttered areas, CW-Doppler, FM-CW and Ultra-Wideband (UWB) short-pulse radar sensors have been used to detect and resolve walking and crawling human targets over ranges measured in hundreds of feet. The limits on detecting crawling targets depend on the height and frequency of the radar sensor because of likely signal cancellation due to ground bounce. Besides being a very low radar cross-section target, the radar response from a crawler close to the ground is especially sensitive to ground bounce cancellation. This is because the differential path lengths between the direct and ground bounce signals are very small. It can be shown that the differential path length, &Dgr;, between the direct wave and that of the ground bounce signal is given by: &Dgr;=2hH/r, where h is the height above ground of the crawler (e.g., 1 foot), H is the height of the radar antenna above the ground, and r is the distance to the crawler. It can be seen that for distances as close as 150 feet, and a radar height of 10 feet, the differential path length before cancellation begins is only &Dgr;=20/150 feet or 0.133 feet. And since the speed of light travels one foot in 1 nanosecond, this translates to a time delay difference of but 133 picoseconds. If the ground is wet, the reflection coefficient can be as high as 0.8. For these reasons, it can be shown that a short pulse UWB radar with a chosen nominal center frequency whose period is four times 133 ps or less will permit detection of crawlers within the first quarter cycle before cancellation begins. This is described in references c and d.
A prime problem is to somehow accommodate, automatically, the varying amounts of ground or sea clutter present within the radar field of view, and still achieve detection while maintaining a high probability of detection and a low probability of false alarm. The subject invention addresses and solves these issues.
OBJECTS AND ADVANTAGES
An object of the subject invention is to detect walking, crawling, running human targets and vehicles in cluttered areas with a high reliability and a low false alarm rate.
It is another object of the invention to detect these targets in cluttered areas over broad angles.
It is yet another object that the invention operate under all weather conditions.
It is still another object that the invention detect small boats approaching the stem of a ship when docked in harbor or at anchor even during rough weather.
It is yet another object that the invention detect unmanned aerial vehicles or hang gliders in a terrorist attack.
It is still another object of the invention to have increased range against airborne targets.
It is yet another object that the cost of the invention be minimal.
It is still another object of the invention that installation take a minimum of time, be in a waterproof container and have virtually no front panel controls.
It is yet another object of the invention to operate for extended periods of time without requiring human intervention in the absence of primary power.
It is still another object of the invention to provide a local and remote alarm signal.
It is yet another object of the invention to provide a covert radio link to transmit an alarm and reset the sensor.
Still further objects and advantages will become apparent from a consideration of the ensuing description and accompanying drawings.
REFERENCES:
patent: 3728632 (1973-04-01), Ross
patent: 3735398 (1973-05-01), Ross
patent: 3739392 (1973-06-01), Ross et al.
patent: 3755696 (1973-08-01), Nicolsen et al.
patent: 3772697 (1973-11-01), Ross
patent: 3858204 (1974-12-01), Robbins et al.
patent: 3858205 (1974-12-01), Ross
patent: 3983422 (1976-09-01), Nicolsen et al.
patent: 4083049 (1978-04-01), Mattern et al.
patent: 5216695 (1993-06-01), Ross et al.
Anro Engineering, Inc.
Grayson George
Swann Glen
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