Abstract:
A selective intrusion detection system includes a Doppler transceiver configured and adapted to receive Doppler return signals indicative of moving targets present in a surveillance space. A processor is operatively connected to the Doppler transceiver to convert Doppler return signals into spectrograms and to determine whether any given spectrogram is indicative of presence of a human or another moving target, like a domestic pet. An alarm is operatively connected to the processor, wherein the processor and alarm are configured to provide an alert in the event the processor determines any given spectrogram is indicative of a human, and to forego providing an alert in the event the processor determines any given spectrogram is indicative of another moving target only.

Description:
RELATED APPLICATIONS 
       [0001]    This application claims the benefit of and priority to U.S. Provisional Patent Application No. 61/915,868 filed Dec. 13, 2013, the contents of which are incorporated herein by reference in their entirety 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention is directed to the field of intrusion detection and alarm systems, and more particularly, to a novel selective intrusion detection system. The selectivity is aimed towards the capability of distinguishing humans from other moving targets that will be used in a variety of fields related to security systems. 
       BACKGROUND OF THE INVENTION 
       [0003]    The concept of intrusion detection systems is well known in the art such as U.S. Pat. No. 6,239,736. However such systems do not contain any selectivity means as disclosed in U.S. Pat. No. 6,239,736. Therefore in many applications, such systems according to the prior art, will be prone to unwanted alarms from for example animals, geo-seismic activities, environmental disturbances (street traffic, water running through pipes, swaying trees, ceiling fans, oscillating fans, air conditioning systems, and the like), that may be moving in or near the surveillance space. For example, for indoor residential settings, pets are a major source of unwanted alarm triggers. In such applications, it is desired to have an alert provided upon the presence of a human intruder, and to forego an alert upon the presence of pets and other moving targets. 
         [0004]    Prior attempts have been made to distinguish the human presence from the presence of other moving targets, but with limited success. Current technologies for monitoring, such as video cameras or microphone arrays, typically involve sensors with high spatial resolution. Such sensors are relatively complex and unreliable as they may require a human in the process loop to watch the signal in real time and manually enter the decision about the signal analyses of the operators observation, that is, whether the signal from such sensor originates from a human or from another moving target. Moreover, video surveillance will present privacy concerns, especially in residential and office surveillance systems. 
         [0005]    There is a need in the art for intrusion detection systems with advanced selectivity in creating an alarm whilst detecting a human intruder, and foregoing an alarm whilst detecting other moving targets autonomously, without the need of a human decision. The present disclosure provides a solution for the functional selective intrusion detection system need and advances the state of the art by providing reliable, robust, and autonomous decision making. 
       SUMMARY OF THE INVENTION 
       [0006]    An intrusion detection system is provided that includes, inter alia, a radar transceiver configured and adapted to receive radar signals indicative of moving targets present in a surveillance space. A processor is operatively connected to the radar transceiver to convert the radar signals into spectrograms and to determine whether any given spectrogram is indicative of presence of a human or another moving target in the surveillance space. An alarm indicator is operatively connected to the processor and is configured to provide an alert in the event the processor determines any given spectrogram is indicative of a human, and to forego providing an alert in the event the processor determines any given spectrogram is indicative only of other moving targets. 
         [0007]    In certain embodiments, the processor is configured and adapted to determine whether any given spectrogram is indicative of a human based on a set of predetermined factors. The set of predetermined factors can include one or more of distribution of maximum Doppler power spectral density, frequency bin of the torso Doppler, frequency bin of the leg Doppler, frequency bins of the −6 dB torso Doppler points, the upper point, the lower point, average power generated by the legs, average of the frequencies with the power higher than a predetermined threshold, Q-factor, and higher order factors. 
         [0008]    In another aspect, the processor can be configured and adapted to determine whether any given spectrogram is indicative of a human based on a predetermined algorithm that calculates an indicator for a human or for other moving targets. For example, if the indicator is defined on a scale from 0.0 to 1.0, with 0.0 being indicative of a other moving targets, and 1.0 being indicative of a human, the processor and alarm can be configured to provide an alert if the indicator has a value greater than about 0.5. In another aspect, the processor can be configured and adapted to convert radar signals into spectrograms using a set of modules including one or more of windowing, overlapping, short-time Fourier transform, clipping, binning, noise elimination, logarithmic conversion, amplitude correction, time grouping, whitening by means of horizontal and vertical bar-removal, vertical smoothing, and horizontal smoothing. 
         [0009]    In certain embodiments, the intrusion detection system also includes a selectivity mode switch which alters the sensitivity of the processor in distinguishing between the presence of a human or another moving target. In certain embodiments, the intrusion system also includes range controlled radar technology operatively connected to the radar transceiver to adjust the surveillance space. 
         [0010]    In certain embodiments, the intrusion detection system also includes a smart diagnostic system operatively connected to the processer to store spectrograms and corresponding user input for human/other moving target determinations to a database and to update determination processes of the processor based on the database. The smart detection system can use a plurality of basic features, such as Doppler strength, support vector machine (SVM) value, and human/other moving target identifiers to functionally save events for diagnostic purposes and continuously improve the performance using ground truth provided by a user or other sensor. In some embodiments, the intrusion detection system further includes communication means operatively connected to the processer to send spectrograms to an up-stream server to enable detailed selectivity processing further up-stream and to alleviate complexity and current consumption constraints down-stream. 
         [0011]    A method of detecting intrusion is also provided, including the steps of converting a radar signal received from a surveillance space into a spectrogram. The method also includes analyzing the spectrogram to determine if any moving targets indicated in the spectrogram are human or other moving targets. 
         [0012]    In certain embodiments, the step of analyzing the spectrogram includes extracting predetermined factors from the spectrogram and calculating an identifier for determining if any moving targets indicated in the spectrogram are human or other moving targets based on applying a predetermined algorithm to the predetermined factors. The method can further include the step of providing an alert for a given identifier value. The predetermined factors set can be indicative of variables in radar spectrograms of humans and other moving targets. The predetermined factors can also include variables that represent motion dynamics and biometric characteristics that distinguish humans and other moving targets. The predetermined factors can also be robust to noise. Test data has shown that accuracy of the system is maintained with an additional three decibels of Gaussian noise 
         [0013]    An embodiment of the selective intrusion detection system is provided that includes, inter alia, a Radar, Sonar or Lidar transceiver configured and adapted to receive Doppler return signals indicative of moving targets present in a surveillance space. A processor is operatively connected to the Doppler transceiver to convert the Doppler return signals into spectrograms and to determine whether any given spectrogram is indicative of presence of a human, or other moving targets moving throughout the surveillance space. The selectivity comprises means to create an alarm indication as a result of genuine intruder motion being present in the surveillance space and forego an alarm in cases of other moving targets (such as domestic pets; cats, dogs, birds, parrot), environmental disturbances (such as greenery, moving trees, weather, rodents, vermin, life stock), IBS (Intrinsic Building Signals, such as air conditioning units, fans, oscillating fans, ceiling fans, fluorescent lighting, geo-seismic activities, or water running through pipes), EMI (electromagnetic interferences, such as RFI radio frequency interference and ESD electrostatic discharges), as well as fluorescent light influence and the like. 
         [0014]    In certain embodiments, the selective intrusion detection system also includes a selectivity mode switch for adapting the selectivity of the processor in order to match the security and financial risk as needed to the application at hand. 
         [0015]    An embodiment of the intrusion alarm system for detecting the presence of a moving target in the presence of interfering phenomena includes a Doppler transceiver for transmitting signals into a surveillance zone; means for reception of Doppler signals returned from said surveillance zone; means for providing a spectrogram; and means for scene analysis of the spectrogram in order to determine respective origins of Doppler targets for providing reliable intrusion security and forgoing privacy issues. The Doppler transceiver can be a radar transceiver, a sonar transceiver, a Lidar transceiver, a range-gated-radar transceiver, or the like. 
         [0016]    An embodiment of the intrusion alarm system for detecting the presence of a moving target in the presence of interfering phenomena includes a Doppler transceiver for transmitting signals into a surveillance zone; means for reception of Doppler signals returned from said surveillance zone; means to provide a spectrogram; means for Doppler signal conditioning; means for scene analysis from momentary spectrogram data; means to evaluate aggregated data; and means to provide statistical analysis. The means for reception of Doppler signals, the means to provide a spectrogram, the means for Doppler signal conditioning, the means for scene analysis, the means to evaluate aggregated data, and the means to provide statistical analysis are all operatively connected to a support-vector-machine that is loaded with a learning kernel trained with real-truths of a multitude of cases, followed by a hierarchical decision making, in order to provide an alert in the case of human target presence in the surveillance zone and to forego an alert in the event of other moving targets and interference phenomenon. The Doppler transceiver can be a radar transceiver, a sonar transceiver, a Lidar transceiver, a range-gated-radar transceiver, or the like. 
         [0017]    In certain embodiments, the spectrogram output signal can be de-noised by nullification of unneeded noise-columns, and/or whitened by reduction of deterministic signals. A plurality of momentary characteristic values of scene-analysis can be calculated and recorded from the spectrogram. The characteristic values can include one or more of the following: tracking a torso velocity of the target, an upper −6 dB point of a torso velocity signal, a lower −6 dB point of a torso velocity signal, tracking a leg velocity of the target, a difference of frequency indices of upper and lower −6 dB points of a torso velocity signal, power generated from a torso signal, an average power generated from a leg signal, an average power per Short Time Fourier Transform, an average power of frequencies between upper and lower −6 dB points of a torso velocity, an average of frequency indices with power over 20 dB with reference to an average background noise, a frequency index at 85% of a cumulative sum of a signal amplitude per Short Time Fourier Transform, a −6 dB Q-factor of power generated from a torso signal. The characteristic values can be recorded over a three-second period of time. 
         [0018]    According to certain embodiments, a plurality of aggregated values can be calculated from the characteristic values. The aggregated values can relate to at least one of the following average torso power, leg periodicity, torso periodicity, phasing between leg and torso periodicity, a ratio between a maximum frequency of leg velocity tracking and an average frequency of torso velocity tracking, a mean of a power spectrum profile, standard deviation of a power spectrum profile, an upper −6 dB point of torso velocity signal periodicity, a lower −6 dB point of torso velocity signal periodicity, phasing between torso periodicity and an upper −6 dB point of torso velocity signal periodicity, phasing between torso periodicity and a lower −6 dB point of torso velocity signal periodicity, phasing between an upper −6 dB point of torso velocity signal periodicity and a lower −6 dB point of torso velocity signal periodicity, a ratio between average torso energy and average leg energy, a standard deviation of a Fast Fourier Transform of torso velocity tracking, a standard deviation of a Fast Fourier Transform of leg velocity tracking. 
         [0019]    A plurality of statistical values can be calculated from the characteristic values. The statistical values can relate to at least one of a mean, a standard deviation, a modal value, a minimum value, a maximum value, and a median value. The statistical values can be selected through at least one of correlations and mutual information, to optimize system selectivity and robustness to noise while minimizing computational cost. The aggregated values and statistical values can provide a decision about an origin of the target by means of a pre-educated support-vector machine. The support vector machine can include local kernel components to separate islands of different classes of events and global kernel components that extend over a whole domain of events, wherein an optimization of parameters of the support vector machine for optimal selectivity is performed by an accelerated random search. Data output from the support vector machine can be passed through hierarchical decision making. 
         [0020]    In certain embodiments, the intrusion alarm system further includes a plurality of settings to adjust a selectivity function. The settings can be optimized for a security application, for a security risk of an installation at hand, for a detection priority need of an installation at hand, or the like. In certain embodiments, learning kernels are re-trained in order to alternate and blend the decision making, to provide an optimum detection solution for an application at hand, and to accommodate needs of security installers and users. A database holding real-truth events can be extended to continuously improve hierarchal decision making. 
         [0021]    In certain embodiments, the intrusion alarm system can further include a recorder to capture and store events. The recorder can rank stored events and record additional events by overwriting lower-ranked events. Ranking of stored events can be based on momentary spectrogram data, aggregated spectrogram data, statistical spectrogram data, hierarchical decision values, a decision indicator, or the like. The recorded events can improve the knowledge base for kernel training. The means for Doppler signal conditioning can be configured so a sensor complexity is decimated at the sensor and increased further upstream in a security chain. The sensor can provide early detection of a possible event by calculation of a Doppler signal standard deviation. The Doppler signal can be digitized, and in such embodiments, the digitized Doppler signal content is compressed, which can be summed to enable forward error correction. The intrusion alarm system can further include a communication protocol. The communication protocol can be energy efficient and/or spectral efficient. 
         [0022]    These and other features of the systems and methods of the subject disclosure will become more readily apparent to those skilled in the art from the following detailed description of the preferred embodiments taken in conjunction with the drawings and tables. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0023]    So that those skilled in the art to which the subject disclosure appertains will readily understand how to make and use the devices of the subject disclosure without undue experimentation, preferred embodiments thereof will be described in detail herein below with reference to certain figures. 
           [0024]      FIG. 1  is a schematic diagram depicting the preferred embodiment in its application showing a surveillance space with a human and other moving targets; 
           [0025]      FIG. 2  is a schematic block diagram of an embodiment; 
           [0026]      FIG. 3  is an explanatory graphical presentation of First Order Time Features; 
           [0027]      FIG. 4  is a hierarchical decision making graph with multiple time scales; 
       
    
    
       [0028]    TABLE 1 is a list of First Order Time Features; 
         [0029]    TABLE 2 is a list of Second Order Time Features; 
         [0030]    TABLE 3 is a list of functionalities of the selectivity mode switch; 
         [0031]    TABLE 4 is a list of optimization methods; and 
         [0032]    TABLE 5 is a list of alternatives for the SVM decision making algorithm. 
       DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0033]    Reference will now be made to the drawings wherein like reference numerals identify similar structural features or aspects of the subject disclosure. For purposes of explanation and illustration, and not limitation, a schematic diagram of an exemplary embodiment of a system for selective intrusion detection in accordance with the disclosure is shown in  FIG. 1  and is designated by reference character  10 . Other embodiments of systems and methods for detecting intrusions in accordance with the disclosure, or aspects thereof, are provided in  FIG. 2 , as will be described. 
         [0034]    Referring to  FIG. 1 , there is shown the preferred embodiment of the present disclosure for a selective intrusion detection system  10 . The intrusion detection system  10  monitors a surveillance space  5 . The surveillance space  5  shows moving targets—e.g. a tree  12 , a heavy street traffic area including EMI, RFI, ESD and the like  13 , a ceiling fan  14 , a cat  15 , a dog  16 , and a human  20 . The intrusion detection system  10  receives Doppler return signals  8  indicative of moving targets  12 ,  13 ,  14 ,  15 ,  16 ,  20  present in and in the vicinity of the surveillance space  5 , determines whether any signals are indicative of the presence of a human  20  or of another moving target  12 ,  13 ,  14 ,  15 ,  16 , and provides an alert in the event a human  20  is indicated, and foregoes providing an alert in the event that other moving targets  12 ,  13 ,  14 ,  15 ,  16  are detected. The selectivity mode switch (ref. Table 3) influences the way the system behavior blends, to provide or forego an alarm in mixed events when a human  20  as well as other moving targets  12 ,  13 ,  14 ,  15 ,  16  are detected. 
         [0035]    Referring to  FIG. 2 , an explanatory schematic block diagram of an embodiment of the selective intrusion detection system is depicted. A Doppler front-end  21  including a sensitivity range setting  22  is operative in the surveillance area and its Doppler return signal from the moving targets present in the surveillance area is processed. At first a buffer  23  is used in order to provide sufficient windowing samples, for example Hanning-windowing, for the spectrogram generator  24  to operate. After completion of the spectral analysis, unneeded noise-columns as well as unwanted deterministic intrinsic building signals, RFI, and the like are removed by de-noising and whitening algorithms  25 . Subsequently First Order Time Features  26  are calculated according to Table 1. The outcome of these First Order Time Features  26  is stored in a 3-second buffer  27 . From this 3-second buffer  27 , Second Order Time Features  28  are calculated according to Table 2. Furthermore statistical values  29  determined from the First Order Time Features  26  are calculated from the content of the 3-second buffer  27 . All results from Second Order Time Features  28  calculations as well as the results from the statistical calculations  29  are incident to the Support Vector Machine  30 , Mode-setting  31  influences the SVM Support Vector Machine decision threshold, residing in the SVM kernel, in order to adapt to the needed security and financial risk, according to Table 3, to suit the security application at hand. Mode-setting  31  may even select different pre-calculated SVM Kernels, since these Kernels contain all parameters needed for wanted real-truth decision making. Alternatives for the SVM decision making algorithm are shown in Table 5. Furthermore the output module  32  will alarm as a conclusion of hierarchical decision making. 
         [0036]    Referring to  FIG. 3 , the horizontal rhythmic lines show the time-evolution of the corresponding First Order Time Features torso velocity tracking  41 , upper −6 dB point of the torso velocity  42 , lower −6 dB point of the torso velocity  43 , and leg velocity tracking  44 . These features are a result of the spectrogram of the human body dynamics and biometric characteristics during movement. For a list of First Order Time Features, reference is made to Table 1. As shown in  FIG. 3 , the momentary average power generated by the leg  47  is calculated by these features. First the delta  45  is calculated between the upper and lower −6 dB points of the torso velocity. Then a sum  48  is taken of the upper −6 dB point of the torso velocity  42  and the delta  45 . Finally the average of the amplitudes over the range from the sum  48  up to and including the leg velocity tracking  44  is used to obtain the momentary average power generated by the leg  47 . 
         [0037]    From the teaching above it should be clear that time-feature analysis is designed to carry-out the human body dynamic analysis in order to track its rhythms and quirks, finding distinguishing factors of the nature (origin) of the target at hand. In electronics theory, Q-factor is conventionally calculated by using the −3 dB points; however, the −6 dB points were used for the set of predetermined factors to provide additional robustness to noise. 
         [0038]      FIG. 4  illustrates the hierarchical decision making where human decisions are available every 50-ms  901  and are combined by hierarchical decision making rules into robust decisions at each second  902 , based on the decision indicator in time  903 , and the decision threshold  905 . The one-second decisions  902  are further combined into 3-second decisions (not visible in  FIG. 4 ). The nonhuman decisions  904  are the result of other moving targets such as IBS Intrinsic Building Signals, EMI, RFI, ESD or pets and the like. These nonhuman decisions are taken at a lower level in the decision hierarchy, while the 50-ms decisions  901  are taken at a higher level and the one-second decisions  902  at an even higher level when an alarm may be triggered. 
         [0039]    The confidence level of the decision is low if the decision indicator  903  is close to the decision threshold  905 , in the undecided interval [0.4, 0.6]. The confidence is high if the decision indicator  903  is close to 1 for human or 0 for non-human. 
         [0040]    Selectivity Optimization 
         [0041]    A rich database with relevant Doppler signals from all events, as mentioned throughout this publication, has been logged, as well as labeled, with real truth analysis by and from experts. During the synthesis of the SVM kernels, regression methods where used to train the behavior of decision making to match this real-truth data as reported by experts. 
         [0042]    In order to boost robustness of the system behavior in adverse Doppler-input conditions, the selectivity of the embodiment has been further optimized by a plurality of methods as mentioned in Table 4. Many intruder attacks as well as quirky human and pet motions have been captured and trained in order to ascertain that the algorithms are living up to the expectations of the security installers and the “voice of their customers”, the users. 
         [0043]    Continuous Improvement of the System Behavior 
         [0044]    In order to continue improving the intrusion detection system of the present disclosure, the system has been be configured for real time learning by capturing events, adding the events to a database, and adjusting the algorithm. Several events will be stored in memory for diagnostic purposes. A ranking system for the events is based on: a) First as well as Second Order Time Features; b) hierarchical decision values; and c) human/other moving target identifier. When this buffer space is fully used, events will only be stored by overwriting a previously stored event. Since this action is destructive for the previously stored event, a smart decision will be taken. The criterion a), b) and c), already mentioned, is used to rank the priority of the events. The least useful event will be replaced with the new event. When needed the event will be read from the buffer and added to the learning database after real truth ranking by an expert. For example, events associated to missed detections or to false alarms are added to the learning database. By adding the most useful events in the learning database, the algorithm learning process yields more accurate results as time progresses, and is as a result thereby the driving continuous improvement of the selective intrusion detection system. 
         [0045]    Grid Computing 
         [0046]    To better leverage available resources, the down-stream (sensor level) processing should be kept to a minimum. Thus only low complexity indicators are used to identify a quiescent state or a possible threat. In the case where more detailed analysis is needed for a selective intrusion detection, the data will not be processed locally. Rather, the data will be communicated up-stream (control panel level or central station level) for decision making by using an efficient protocol. In such case the tasks for the sensor to be executed are: (1) early detection of a possible event, e.g. by calculation of the Doppler signal standard deviation (RMS-value); (2) Doppler signal digitization; (3) source compression to reduce redundant data; (4) forward error correction to maximize good throughput; and (5) handling the communication protocol. These remaining tasks will decimate complexity of the decision making algorithms and enable up-stream processing. Implementation can be either wired or wireless, so long as the communication method remains efficient, in terms of energy consumption per bit communicated [nano-Joule/bit] and in terms of spectral efficiency [(bits/s)/Hz]. To maintain an efficient communication method, interference with the radar, sonar and lidar operation should be avoided so as not to influence its Doppler output.