Source: https://insight.rpxcorp.com/pat/US6614384B2
Timestamp: 2019-10-14 00:49:35
Document Index: 107851552

Matched Legal Cases: ['art 1508', 'art 1508', 'art 1508', 'art 1508', 'art 1508', 'art 1508', 'art 1508', 'arts 1508', 'art 1508', 'art 1508', 'art 1508', 'art 1508', 'art 1508', 'art 1508', 'art 1508', 'art 1508', 'art 1508', 'art 1508', 'art 1508', 'arts 1508', 'art 1508', 'art 1508', 'art 1508', 'art 1508', 'art 1508', 'art 1508', 'art 1508', 'art 1508', 'art 1508', 'art 1508']

Patent US 6,614,384 B2
US 20110084833A1
Impulse radio systems with multiple pulse types
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Radar intrusion detection system
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CONTROL DATA CANADA LIMITED A CORP. OF CANADA
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each of said plurality of receiving impulse radio units receives the impulse radio signal at and after a subsequent time and generates a second waveform which is a time domain representation of the received impulse radio signal that indicates an actual distortion of the transmitted impulse radio signal that was transmitted within the protection zone at and after the subsequent time, each receiving impulse radio unit further includes;
<FGREF>FIG. 1F</FGREF> graphically depicts the frequency plot of the Gaussian family of the Gaussian Pulse and the first, second, and third derivative.
<FGREF>FIG. 3</FGREF> illustrates the cross-correlation of two codes graphically as Coincidences vs. Time Offset;
<FGREF>FIGS. 4A-4E</FGREF> graphically illustrate five modulation techniques to include: Early-Late Modulation; One of Many Modulation; Flip Modulation; Quad Flip Modulation; and Vector Modulation;
<FGREF>FIG. 5A</FGREF> illustrates representative signals of an interfering signal, a coded received pulse train and a coded reference pulse train;
<FGREF>FIG. 5B</FGREF> depicts a typical geometrical configuration giving rise to multipath received signals;
<FGREF>FIG. 5C</FGREF> illustrates exemplary multipath signals in the time domain;
<FGREF>FIGS. 5D-5F</FGREF> illustrate a signal plot of various multipath environments.
<FGREF>FIG. 5G</FGREF> illustrates the Rayleigh fading curve associated with non-impulse radio transmissions in a multipath environment.
<FGREF>FIG. 5H</FGREF> illustrates a plurality of multipaths with a plurality of reflectors from a transmitter to a receiver.
<FGREF>FIG. 5I</FGREF> graphically represents signal strength as volts vs. time in a direct path and multipath environment.
<FGREF>FIG. 9</FGREF> illustrates an exemplary block diagram of an ultra-wideband scanning receiver that could be used in the present invention.
<FGREF>FIG. 10</FGREF> illustrates an exemplary block diagram of an ultra-wideband scanning transmitter that could be used in the present invention.
<FGREF>FIG. 11</FGREF> illustrates a diagram of the basic components of a first embodiment of the intrusion detection system in accordance with the present invention (see also FIG. 14).
<FGREF>FIG. 12</FGREF> illustrates a diagram of the basic components of a second embodiment of the intrusion detection system in accordance with the present invention (see also FIG. 17).
<FGREF>FIG. 13</FGREF> illustrates an example of a specially shaped protection zone associated with a third embodiment in accordance with the present invention (see also FIG. 20).
<FGREF>FIG. 14</FGREF> illustrates in greater detail a diagram of the basic components of the first embodiment of the intrusion detection system in accordance with the present invention.
<FGREF>FIGS. 15</FGREF>a-15b illustrate an exemplary first waveform and an exemplary second waveform that could be generated by a receiving impulse radio unit shown in FIG. 14.
<FGREF>FIG. 16</FGREF> illustrates a flowchart of the basic steps of a first embodiment of the preferred method in accordance with the present invention.
<FGREF>FIG. 17</FGREF> illustrates in greater detail a diagram of the basic components of a second embodiment of the intrusion detection system in accordance with the present invention.
<FGREF>FIGS. 18</FGREF>a-18b illustrate exemplary first waveforms and exemplary second waveforms that could be generated by three different receiving impulse radio units shown in FIG. 17.
<FGREF>FIGS. 19</FGREF>a-19b illustrates a flowchart of the basic steps of a second embodiment of the preferred method in accordance with the present invention.
<FGREF>FIG. 20</FGREF> illustrates in greater detail a diagram of the basic components of a third embodiment of the intrusion detection system in accordance with the present invention.
<FGREF>FIGS. 21</FGREF>a-21b illustrates a flowchart of the basic steps of a third embodiment of the preferred method in accordance with the present invention.
<FGREF>FIG. 22</FGREF> illustrates a diagram of the intrusion detection system incorporating one or more directive antennas.
For analysis purposes, it is convenient to model pulse waveforms in an ideal manner. For example, the transmitted waveform produced by supplying a step function into an ultra-wideband antenna may be modeled as a Gaussian monocycle. A Gaussian monocycle (normalized to a peak value of 1) may be described by: <CWU><MATH-US><MATHEMATICA></MATHEMATICA><MATHML><math><mrow><mrow><msub><mi>f</mi><mi>mono</mi></msub><mo>⁢;</mo><mrow><mo>(</mo><mi>t</mi><mo>)</mo></mrow></mrow><mo>=</mo><mrow><msqrt><mi>ⅇ;</mi></msqrt><mo>⁢;</mo><mrow><mo>(</mo><mfrac><mi>t</mi><mi>σ</mi></mfrac><mo>)</mo></mrow><mo>⁢;</mo><msup><mi>ⅇ;</mi><mfrac><mrow><mo>-</mo><msup><mi>t</mi><mn>2</mn></msup></mrow><mrow><mn>2</mn><mo>⁢;</mo><msup><mi>σ</mi><mn>2</mn></msup></mrow></mfrac></msup></mrow></mrow></math></MATHML><EMI></EMI></MATH-US></CWU>
The power special density of the Gaussian monocycle is shown in <FGREF>FIG. 1F</FGREF>, along with spectrums for the Gaussian pulse, triplet, and quadlet. The corresponding equation for the Gaussian monocycle is: <CWU><MATH-US><MATHEMATICA></MATHEMATICA><MATHML><math><mrow><mrow><msub><mi>F</mi><mi>mono</mi></msub><mo>⁢;</mo><mrow><mo>(</mo><mi>f</mi><mo>)</mo></mrow></mrow><mo>=</mo><mrow><msup><mrow><mo>(</mo><mrow><mn>2</mn><mo>⁢;</mo><mstyle><mtext> </mtext></mstyle><mo>⁢;</mo><mi>π</mi></mrow><mo>)</mo></mrow><mfrac><mn>3</mn><mn>2</mn></mfrac></msup><mo>⁢;</mo><mi>σ</mi><mo>⁢;</mo><mstyle><mtext> </mtext></mstyle><mo>⁢;</mo><mi>f</mi><mo>⁢;</mo><mstyle><mtext> </mtext></mstyle><mo>⁢;</mo><msup><mi>ⅇ;</mi><mrow><mrow><mo>-</mo><mn>2</mn></mrow><mo>⁢;</mo><msup><mrow><mo>(</mo><mrow><mi>π</mi><mo>⁢;</mo><mstyle><mtext> </mtext></mstyle><mo>⁢;</mo><mi>σ</mi><mo>⁢;</mo><mstyle><mtext> </mtext></mstyle><mo>⁢;</mo><mi>f</mi></mrow><mo>)</mo></mrow><mn>2</mn></msup></mrow></msup></mrow></mrow></math></MATHML><EMI></EMI></MATH-US></CWU>
The center frequency (f<HIL><SB>c</SB></HIL>), or frequency of peak spectral density, of the Gaussian monocycle is: <CWU><MATH-US><MATHEMATICA></MATHEMATICA><MATHML><math><mrow><msub><mi>f</mi><mi>c</mi></msub><mo>=</mo><mfrac><mn>1</mn><mrow><mn>2</mn><mo>⁢;</mo><mstyle><mtext> </mtext></mstyle><mo>⁢;</mo><mi>π</mi><mo>⁢;</mo><mstyle><mtext> </mtext></mstyle><mo>⁢;</mo><mi>σ</mi></mrow></mfrac></mrow></math></MATHML><EMI></EMI></MATH-US></CWU>
Impulse transmission systems may communicate one or more data bits with a single pulse; however, typically each data bit is communicated using a sequence of pulses, known as a pulse train. As described in detail in the following example system, the impulse radio transmitter produces and outputs a train of pulses for each bit of information. <FGREF>FIGS. 2A and 2B</FGREF> are illustrations of the output of a typical 10 megapulses per second (Mpps) system with uncoded, unmodulated pulses, each having a width of 0.5 nanoseconds (ns). <FGREF>FIG. 2A</FGREF> shows a time domain representation of the pulse train output. <FGREF>FIG. 2B</FGREF> illustrates that the result of the pulse train in the frequency domain is to produce a spectrum comprising a set of comb lines spaced at the frequency of the 10 Mpps pulse repetition rate. When the full spectrum is shown, as in <FGREF>FIG. 2C</FGREF>, the envelope of the comb line spectrum corresponds to the curve of the single Gaussian monocycle spectrum in FIG. 1F. For this simple uncoded case, the power of the pulse train is spread among roughly two hundred comb lines. Each comb line thus has a small fraction of the total power and presents much less of an interference problem to a receiver sharing the band. It can also be observed from <FGREF>FIG. 2A</FGREF> that impulse transmission systems typically have very low average duty cycles, resulting in average power lower than peak power. The duty cycle of the signal in <FGREF>FIG. 2A</FGREF> is 0.5%, based on a 0.5 ns pulse duration in a 100 ns interval.
The signal of an uncoded, unmodulated pulse train may be expressed: <CWU><MATH-US><MATHEMATICA></MATHEMATICA><MATHML><math><mrow><mrow><mi>s</mi><mo>⁢;</mo><mrow><mo>(</mo><mi>t</mi><mo>)</mo></mrow></mrow><mo>=</mo><mrow><msup><mrow><mo>(</mo><mrow><mo>-</mo><mn>1</mn></mrow><mo>)</mo></mrow><mi>f</mi></msup><mo>⁢;</mo><mi>a</mi><mo>⁢;</mo><mrow><munder><mo>∑;</mo><mi>j</mi></munder><mo>⁢;</mo><mrow><mi>ω</mi><mo>⁢;</mo><mrow><mo>(</mo><mrow><mrow><mi>ct</mi><mo>-</mo><msub><mi>jT</mi><mi>f</mi></msub></mrow><mo>,</mo><mi>b</mi></mrow><mo>)</mo></mrow></mrow></mrow></mrow></mrow></math></MATHML><EMI></EMI></MATH-US></CWU>
where j is the index of a pulse within a pulse train, (−1)<HIL><SP>f </SP></HIL>is polarity (+;/−), a is pulse amplitude, b is pulse type, c is pulse width, ω(t,b) is the normalized pulse waveform, and T<HIL><SB>f </SB></HIL>is pulse repetition time.
The energy spectrum of a pulse train signal over a frequency bandwidth of interest may be determined by summing the phasors of the pulses at each frequency, using the following equation: <CWU><MATH-US><MATHEMATICA></MATHEMATICA><MATHML><math><mrow><mrow><mi>A</mi><mo>⁢;</mo><mrow><mo>(</mo><mi>ω</mi><mo>)</mo></mrow></mrow><mo>=</mo><mrow><mo>&LeftBracketingBar;</mo><mrow><munderover><mo>∑;</mo><mrow><mi>i</mi><mo>=</mo><mn>1</mn></mrow><mi>n</mi></munderover><mo>⁢;</mo><mstyle><mtext> </mtext></mstyle><mo>⁢;</mo><mfrac><msup><mi>ⅇ;</mi><mrow><mi>jΔ</mi><mo>⁢;</mo><mstyle><mtext> </mtext></mstyle><mo>⁢;</mo><mi>t</mi></mrow></msup><mi>n</mi></mfrac></mrow><mo>&RightBracketingBar;</mo></mrow></mrow></math></MATHML><EMI></EMI></MATH-US></CWU>
Specialized coding techniques can be employed to specify temporal and/or non-temporal pulse characteristics to produce a pulse train having certain spectral and/or correlation properties. For example, by employing a PN code to vary inter-pulse spacing, the energy in the comb lines presented in <FGREF>FIG. 2B</FGREF> can be distributed to other frequencies as depicted in <FGREF>FIG. 2D</FGREF>, thereby decreasing the peak spectral density within a bandwidth of interest. Note that the spectrum retains certain properties that depend on the specific (temporal) PN code used. Spectral properties can be similarly affected by using non-temporal coding (e.g., inverting certain pulses).
Coding provides a method of establishing independent communication channels. Specifically, families of codes can be designed such that the number of pulse coincidences between pulse trains produced by any two codes will be minimal. For example, <FGREF>FIG. 3</FGREF> depicts cross-correlation properties of two codes that have no more than four coincidences for any time offset. Generally, keeping the number of pulse collisions minimal represents a substantial attenuation of the unwanted signal.
The signal of a coded pulse train can be generally expressed by: <CWU><MATH-US><MATHEMATICA></MATHEMATICA><MATHML><math><mrow><mrow><msubsup><mi>S</mi><mi>tr</mi><mrow><mo>(</mo><mi>k</mi><mo>)</mo></mrow></msubsup><mo>⁢;</mo><mrow><mo>(</mo><mi>t</mi><mo>)</mo></mrow></mrow><mo>=</mo><mrow><munder><mo>∑;</mo><mi>j</mi></munder><mo>⁢;</mo><mrow><msup><mrow><mo>(</mo><mrow><mo>-</mo><mn>1</mn></mrow><mo>)</mo></mrow><msubsup><mi>f</mi><mi>j</mi><mrow><mo>(</mo><mi>k</mi><mo>)</mo></mrow></msubsup></msup><mo>⁢;</mo><msubsup><mi>a</mi><mi>j</mi><mrow><mo>(</mo><mi>k</mi><mo>)</mo></mrow></msubsup><mo>⁢;</mo><mrow><mi>ω</mi><mo>⁢;</mo><mrow><mo>(</mo><mrow><mrow><mrow><msubsup><mi>c</mi><mi>j</mi><mrow><mo>(</mo><mi>k</mi><mo>)</mo></mrow></msubsup><mo>⁢;</mo><mi>t</mi></mrow><mo>-</mo><msubsup><mi>T</mi><mi>j</mi><mrow><mo>(</mo><mi>k</mi><mo>)</mo></mrow></msubsup></mrow><mo>,</mo><msubsup><mi>b</mi><mi>j</mi><mrow><mo>(</mo><mi>k</mi><mo>)</mo></mrow></msubsup></mrow><mo>)</mo></mrow></mrow></mrow></mrow></mrow></math></MATHML><EMI></EMI></MATH-US></CWU>
where k is the index of a transmitter, j is the index of a pulse within its pulse train, (−1)f<HIL><SB>j</SB></HIL><HIL><SP>(k)</SP></HIL>, a<HIL><SB>j</SB></HIL><HIL><SP>(k)</SP></HIL>, b<HIL><SB>j</SB></HIL><HIL><SP>(k)</SP></HIL>, c<HIL><SB>j</SB></HIL><HIL><SP>(k)</SP></HIL>, and ω(t,b<HIL><SB>j</SB></HIL><HIL><SP>(k)</SP></HIL>) are the coded polarity, pulse amplitude, pulse type, pulse width, and normalized pulse waveform of the jth pulse of the kth transmitter, and T<HIL><SB>j</SB></HIL><HIL><SP>(k) </SP></HIL>is the coded time shift of the jth pulse of the kth transmitter. Note: When a given non-temporal characteristic does not vary (i.e., remains constant for all pulses), it becomes a constant in front of the summation sign.
A pulse train with conventional ‘early-late’ time-shift modulation can be expressed: <CWU><MATH-US><MATHEMATICA></MATHEMATICA><MATHML><math><mrow><mrow><msubsup><mi>S</mi><mi>tr</mi><mrow><mo>(</mo><mi>k</mi><mo>)</mo></mrow></msubsup><mo>⁢;</mo><mrow><mo>(</mo><mi>t</mi><mo>)</mo></mrow></mrow><mo>=</mo><mrow><munder><mo>∑;</mo><mi>j</mi></munder><mo>⁢;</mo><mrow><msup><mrow><mo>(</mo><mrow><mo>-</mo><mn>1</mn></mrow><mo>)</mo></mrow><msubsup><mi>f</mi><mi>j</mi><mrow><mo>(</mo><mi>k</mi><mo>)</mo></mrow></msubsup></msup><mo>⁢;</mo><msubsup><mi>a</mi><mi>j</mi><mrow><mo>(</mo><mi>k</mi><mo>)</mo></mrow></msubsup><mo>⁢;</mo><mrow><mi>ω</mi><mo>⁢;</mo><mrow><mo>(</mo><mrow><mrow><mrow><msubsup><mi>c</mi><mi>j</mi><mrow><mo>(</mo><mi>k</mi><mo>)</mo></mrow></msubsup><mo>⁢;</mo><mi>t</mi></mrow><mo>-</mo><mrow><msubsup><mi>T</mi><mi>j</mi><mrow><mo>(</mo><mi>k</mi><mo>)</mo></mrow></msubsup><mo>⁢;</mo><mi>δ</mi><mo>⁢;</mo><mstyle><mtext> </mtext></mstyle><mo>⁢;</mo><msubsup><mi>d</mi><mrow><mo>[</mo><mrow><mi>j</mi><mo>/</mo><msub><mi>N</mi><mi>s</mi></msub></mrow><mo>]</mo></mrow><mrow><mo>(</mo><mi>k</mi><mo>)</mo></mrow></msubsup></mrow></mrow><mo>,</mo><msubsup><mi>b</mi><mi>j</mi><mrow><mo>(</mo><mi>k</mi><mo>)</mo></mrow></msubsup></mrow><mo>)</mo></mrow></mrow></mrow></mrow></mrow></math></MATHML><EMI></EMI></MATH-US></CWU>
where k is the index of a transmitter, j is the index of a pulse within its pulse train, (−1)f<HIL><SB>j</SB></HIL><HIL><SP>(k)</SP></HIL>, a<HIL><SB>j</SB></HIL><HIL><SP>(k)</SP></HIL>, b<HIL><SB>j</SB></HIL><HIL><SP>(k)</SP></HIL>, c<HIL><SB>j</SB></HIL><HIL><SP>(k)</SP></HIL>, and ω(t, b<HIL><SB>j</SB></HIL><HIL><SP>(k)</SP></HIL>) are the coded polarity, pulse amplitude, pulse type, pulse width, and normalized pulse waveform of the jth pulse of the kth transmitter, T<HIL><SB>j</SB></HIL><HIL><SP>(k) </SP></HIL>is the coded time shift of the jth pulse of the kth transmitter, δ is the time shift added when the transmitted symbol is 1 (instead of 0), d<HIL><SP>(k) </SP></HIL>is the data (i.e., 0 or 1) transmitted by the kth transmitter, and N<HIL><SB>s </SB></HIL>is the number of pulses per symbol (e.g., bit). Similar expressions can be derived to accommodate other proposed forms of modulation.
An alternative form of time-shift modulation can be described as One-of-Many Position Modulation (OMPM). The OMPM approach, shown in <FGREF>FIG. 4B</FGREF>, involves shifting a pulse to one of N possible modulation positions about a nominal coded (or uncoded) time position in response to an information signal, where N represents the number of possible states. For example, if N were four (4), two data bits of information could be conveyed. For further details regarding OMPM, see “Apparatus, System and Method for One-of-Many Position Modulation in an Impulse Radio Communication System,” Attorney Docket No. 1659.0860000, filed Jun. 7, 2000, assigned to the assignee of the present invention, and incorporated herein by reference.
Besides providing channelization and energy smoothing, coding makes impulse radios highly resistant to interference by enabling discrimination between intended impulse transmissions and interfering transmissions. This property is desirable since impulse radio systems must share the energy spectrum with conventional radio systems and with other impulse radio systems. <FGREF>FIG. 5A</FGREF> illustrates the result of a narrow band sinusoidal interference signal 502 overlaying an impulse radio signal 504. At the impulse radio receiver, the input to the cross correlation would include the narrow band signal 502 and the received ultrawide-band impulse radio signal 504. The input is sampled by the cross correlator using a template signal 506 positioned in accordance with a code. Without coding, the cross correlation would sample the interfering signal 502 with such regularity that the interfering signals could cause interference to the impulse radio receiver. However, when the transmitted impulse signal is coded and the impulse radio receiver template signal 506 is synchronized using the identical code, the receiver samples the interfering signals non-uniformly. The samples from the interfering signal add incoherently, increasing roughly according to the square root of the number of samples integrated. The impulse radio signal samples, however, add coherently, increasing directly according to the number of samples integrated. Thus, integrating over many pulses overcomes the impact of interference.
The average output signal-to-noise ratio of the impulse radio may be calculated for randomly selected time-hopping codes as a function of the number of active users, N<HIL><SB>u</SB></HIL>, as: <CWU><MATH-US><MATHEMATICA></MATHEMATICA><MATHML><math><mrow><mrow><msub><mi>SNR</mi><mi>out</mi></msub><mo>⁢;</mo><mrow><mo>(</mo><msub><mi>N</mi><mi>u</mi></msub><mo>)</mo></mrow></mrow><mo>=</mo><mfrac><msup><mrow><mo>(</mo><mrow><msub><mi>N</mi><mi>s</mi></msub><mo>⁢;</mo><msub><mi>A</mi><mn>1</mn></msub><mo>⁢;</mo><msub><mi>m</mi><mi>p</mi></msub></mrow><mo>)</mo></mrow><mn>2</mn></msup><mrow><msubsup><mi>σ</mi><mi>rec</mi><mn>2</mn></msubsup><mo>+</mo><mrow><msub><mi>N</mi><mi>s</mi></msub><mo>⁢;</mo><msubsup><mi>σ</mi><mi>a</mi><mn>2</mn></msubsup><mo>⁢;</mo><mrow><munderover><mo>∑;</mo><mrow><mi>k</mi><mo>=</mo><mn>2</mn></mrow><msub><mi>N</mi><mi>u</mi></msub></munderover><mo>⁢;</mo><mstyle><mtext> </mtext></mstyle><mo>⁢;</mo><msubsup><mi>A</mi><mi>k</mi><mn>2</mn></msubsup></mrow></mrow></mrow></mfrac></mrow></math></MATHML><EMI></EMI></MATH-US></CWU>
where N<HIL><SB>s </SB></HIL>is the number of pulses integrated per bit of information, A<HIL><SB>k </SB></HIL>models the attenuation of transmitter k's signal over the propagation path to the receiver, and σ<HIL><SB>rec</SB></HIL><HIL><SP>2 </SP></HIL>is the variance of the receiver noise component at the pulse train integrator output. The monocycle waveform-dependent parameters m<HIL><SB>p </SB></HIL>and σ<HIL><SB>a</SB></HIL><HIL><SP>2 </SP></HIL>are given by <CWU><MATH-US><MATHEMATICA></MATHEMATICA><MATHML><math><mtable><mtr><mtd><mrow><msub><mi>m</mi><mi>p</mi></msub><mo>=</mo><mstyle><mtext> </mtext></mstyle><mo>⁢;</mo><mrow><msubsup><mo>∫;</mo><mrow><mo>-</mo><mi>∞</mi></mrow><mi>∞</mi></msubsup><mo>⁢;</mo><mrow><mrow><mrow><mi>ω</mi><mo>⁡;</mo><mrow><mo>(</mo><mi>t</mi><mo>)</mo></mrow></mrow><mo>⁡;</mo><mrow><mo>[</mo><mrow><mrow><mi>ω</mi><mo>⁡;</mo><mrow><mo>(</mo><mi>t</mi><mo>)</mo></mrow></mrow><mo>-</mo><mrow><mi>ω</mi><mo>⁡;</mo><mrow><mo>(</mo><mrow><mi>t</mi><mo>-</mo><mi>δ</mi></mrow><mo>)</mo></mrow></mrow></mrow><mo>]</mo></mrow></mrow><mo>⁢;</mo><mstyle><mtext> </mtext></mstyle><mo>⁢;</mo><mrow><mo>ⅆ;</mo><mi>t</mi></mrow></mrow></mrow></mrow></mtd></mtr><mtr><mtd><mrow><mstyle><mtext> </mtext></mstyle><mo>⁢;</mo><mi>and</mi></mrow></mtd></mtr><mtr><mtd><mrow><mrow><msubsup><mi>σ</mi><mi>a</mi><mn>2</mn></msubsup><mo>=</mo><mstyle><mtext> </mtext></mstyle><mo>⁢;</mo><mrow><msubsup><mi>T</mi><mi>f</mi><mrow><mo>-</mo><mn>1</mn></mrow></msubsup><mo>⁢;</mo><mrow><msubsup><mo>∫;</mo><mrow><mo>-</mo><mi>∞</mi></mrow><mi>∞</mi></msubsup><mo>⁢;</mo><mrow><msup><mrow><mo>[</mo><mrow><msubsup><mo>∫;</mo><mrow><mo>-</mo><mi>∞</mi></mrow><mi>∞</mi></msubsup><mo>⁢;</mo><mrow><mrow><mi>ω</mi><mo>⁡;</mo><mrow><mo>(</mo><mrow><mi>t</mi><mo>-</mo><mi>s</mi></mrow><mo>)</mo></mrow></mrow><mo>⁢;</mo><mrow><mi>υ</mi><mo>⁡;</mo><mrow><mo>(</mo><mi>t</mi><mo>)</mo></mrow></mrow><mo>⁢;</mo><mstyle><mtext> </mtext></mstyle><mo>⁢;</mo><mrow><mo>ⅆ;</mo><mi>t</mi></mrow></mrow></mrow><mo>]</mo></mrow><mn>2</mn></msup><mo>⁢;</mo><mstyle><mtext> </mtext></mstyle><mo>⁢;</mo><mrow><mo>ⅆ;</mo><mi>s</mi></mrow></mrow></mrow></mrow></mrow><mo>,</mo></mrow></mtd></mtr></mtable></math></MATHML><EMI></EMI></MATH-US></CWU>
where ω(t) is the monocycle waveform, u(t)=;ω(t)−ω(t−δ) is the template signal waveform, δ is the time shift between the monocycle waveform and the template signal waveform, T<HIL><SB>f </SB></HIL>is the pulse repetition time, and s is signal.
Impulse radios, however, can be substantially resistant to multipath effects. Impulses arriving from delayed multipath reflections typically arrive outside of the correlation time and, thus, may be ignored. This process is described in detail with reference to <FGREF>FIGS. 5B and 5C</FGREF>. <FGREF>FIG. 5B</FGREF> illustrates a typical multipath situation, such as in a building, where there are many reflectors 504B, 505B. In this figure, a transmitter 506B transmits a signal that propagates along three paths, the direct path 501B, path 1502B, and path 2503B, to a receiver 508B, where the multiple reflected signals are combined at the antenna. The direct path 501B, representing the straight-line distance between the transmitter and receiver, is the shortest. Path 1502B represents a multipath reflection with a distance very close to that of the direct path. Path 2503B represents a multipath reflection with a much longer distance. Also shown are elliptical (or, in space, ellipsoidal) traces that represent other possible locations for reflectors that would produce paths having the same distance and thus the same time delay.
<FGREF>FIG. 5C</FGREF> illustrates the received composite pulse waveform resulting from the three propagation paths 501B, 502B, and 503B shown in FIG. 5B. In this figure, the direct path signal 501B is shown as the first pulse signal received. The path 1 and path 2 signals 502B, 503B comprise the remaining multipath signals, or multipath response, as illustrated. The direct path signal is the reference signal and represents the shortest propagation time. The path 1 signal is delayed slightly and overlaps and enhances the signal strength at this delay value. The path 2 signal is delayed sufficiently that the waveform is completely separated from the direct path signal. Note that the reflected waves are reversed in polarity. If the correlator template signal is positioned such that it will sample the direct path signal, the path 2 signal will not be sampled and thus will produce no response. However, it can be seen that the path 1 signal has an effect on the reception of the direct path signal since a portion of it would also be sampled by the template signal. Generally, multipath signals delayed less than one quarter wave (one quarter wave is about 1.5 inches, or 3.5 cm at 2 GHz center frequency) may attenuate the direct path signal. This region is equivalent to the first Fresnel zone in narrow band systems. Impulse radio, however, has no further nulls in the higher Fresnel zones. This ability to avoid the highly variable attenuation from multipath gives impulse radio significant performance advantages.
<FGREF>FIGS. 5D</FGREF>, 5E, and 5F represent the received signal from a TM-UWB transmitter in three different multipath environments. These figures are approximations of typical signal plots. <FGREF>FIG. 5D</FGREF> illustrates the received signal in a very low multipath environment. This may occur in a building where the receiver antenna is in the middle of a room and is a relatively short, distance, for example, one meter, from the transmitter. This may also represent signals received from a larger distance, such as 100 meters, in an open field where there are no objects to produce reflections. In this situation, the predominant pulse is the first received pulse and the multipath reflections are too weak to be significant. <FGREF>FIG. 5E</FGREF> illustrates an intermediate multipath environment. This approximates the response from one room to the next in a building. The amplitude of the direct path signal is less than in FIG. 5D and several reflected signals are of significant amplitude. <FGREF>FIG. 5F</FGREF> approximates the response in a severe multipath environment such as propagation through many rooms, from corner to corner in a building, within a metal cargo hold of a ship, within a metal truck trailer, or within an intermodal shipping container. In this scenario, the main path signal is weaker than in FIG. 5E. In this situation, the direct path signal power is small relative to the total signal power from the reflections.
Where the system of <FGREF>FIG. 5B</FGREF> is a narrow band system and the delays are small relative to the data bit time, the received signal is a sum of a large number of sine waves of random amplitude and phase. In the idealized limit, the resulting envelope amplitude has been shown to follow a Rayleigh probability distribution as follows: <CWU><MATH-US><MATHEMATICA></MATHEMATICA><MATHML><math><mrow><mrow><mi>p</mi><mo>⁢;</mo><mrow><mo>(</mo><mi>r</mi><mo>)</mo></mrow></mrow><mo>=</mo><mrow><mfrac><mi>r</mi><msup><mi>σ</mi><mn>2</mn></msup></mfrac><mo>⁢;</mo><mrow><mi>exp</mi><mo>⁢;</mo><mrow><mo>(</mo><mfrac><mrow><mo>-</mo><msup><mi>r</mi><mn>2</mn></msup></mrow><mrow><mn>2</mn><mo>⁢;</mo><mstyle><mtext> </mtext></mstyle><mo>⁢;</mo><msup><mi>σ</mi><mn>2</mn></msup></mrow></mfrac><mo>)</mo></mrow></mrow></mrow></mrow></math></MATHML><EMI></EMI></MATH-US></CWU>
where r is the envelope amplitude of the combined multipath signals, and σ(2)<HIL><SP>1/2 </SP></HIL>is the RMS power of the combined multipath signals. The Rayleigh distribution curve in <FGREF>FIG. 5G</FGREF> shows that 10% of the time, the signal is more than 10 dB attenuated. This suggests that 10 dB fade margin is needed to provide 90% link availability. Values of fade margin from 10 to 40 dB have been suggested for various narrow band systems, depending on the required reliability. This characteristic has been the subject of much research and can be partially improved by such techniques as antenna and frequency diversity, but these techniques result in additional complexity and cost.
In a high multipath environment such as inside homes, offices, warehouses, automobiles, trailers, shipping containers, or outside in an urban canyon or other situations where the propagation is such that the received signal is primarily scattered energy, impulse radio systems can avoid the Rayleigh fading mechanism that limits performance of narrow band systems, as illustrated in <FGREF>FIGS. 5H and 5I</FGREF>. <FGREF>FIG. 5H</FGREF> depicts an impulse radio system in a high multipath environment 500H consisting of a transmitter 506H and a receiver 508H. A transmitted signal follows a direct path 501H and reflects off reflectors 503H via multiple paths 502H. <FGREF>FIG. 5I</FGREF> illustrates the combined signal received by the receiver 508H over time with the vertical axis being signal strength in volts and the horizontal axis representing time in nanoseconds. The direct path 501H results in the direct path signal 502I while the multiple paths 502H result in multipath signals 504I. In the same manner described earlier for <FGREF>FIGS. 5B and 5C</FGREF>, the direct path signal 502I is sampled, while the multipath signals 504I are not, resulting in Rayleigh fading avoidance.
A pulse generator 622 uses the modulated, coded timing signal 618 as a trigger signal to generate output pulses. The output pulses are provided to a transmit antenna 624 via a transmission line 626 coupled thereto. The output pulses are converted into propagating electromagnetic pulses by the transmit antenna 624. The electromagnetic pulses are called the emitted signal, and propagate to an impulse radio receiver 702, such as shown in <FGREF>FIG. 7</FGREF>, through a propagation medium. In a preferred embodiment, the emitted signal is wide-band or ultrawide-band, approaching a monocycle pulse as in FIG. 1B. However, the emitted signal may be spectrally modified by filtering of the pulses, which may cause them to have more zero crossings (more cycles) in the time domain, requiring the radio receiver to use a similar waveform as the template signal for efficient conversion.
<FGREF>FIGS. 8A-8C</FGREF> illustrate the cross correlation process and the correlation function. <FGREF>FIG. 8A</FGREF> shows the waveform of a template signal. <FGREF>FIG. 8B</FGREF> shows the waveform of a received impulse radio signal at a set of several possible time offsets. <FGREF>FIG. 8C</FGREF> represents the output of the cross correlator for each of the time offsets of FIG. 8B. For any given pulse received, there is a corresponding point that is applicable on this graph. This is the point corresponding to the time offset of the template signal used to receive that pulse. Further examples and details of precision timing can be found described in U.S. Pat. No. 5,677,927, and commonly owned co-pending application application Ser. No. 09/146,524, now U.S. Pat. No. 6,304,623, filed Sep. 3, 1998, titled “Precision Timing Generator System and Method,” both of which are incorporated herein by reference.
Referring to <FGREF>FIGS. 9-22</FGREF>, there are disclosed three embodiments of exemplary intrusion detection systems 1100, 1100′ and 1100″ and preferred methods 1600, 1600′ and 1600″ in accordance with the present invention.
Generally, in the first embodiment, the intrusion detection system 1100 and method 1600 utilize impulse radio technology to detect when an intruder 1102 has entered a protection zone 1104 (see FIGS. 11 and 14-16). In the second embodiment, the intrusion detection system 1100′ and method 1600′ can utilize impulse radio technology to determine a location of the intruder 1102′ within the protection zone 1104′ and also track the movement of the intruder 1102′ within the protection zone 1104′ (see FIGS. 12 and 17-19). In the third embodiment, the intrusion detection system 1100″ and method 1600″ utilize impulse radio technology to create a specially shaped protection zone 1104″ before trying to detect when and where the intruder 1102″ has penetrated and moved within the protection zone 1104″ (see FIGS. 13 and 20-21). Each of the three embodiments are briefly described below with respect to <FGREF>FIGS. 9-13</FGREF> prior to describing each embodiment in greater detail with respect to <FGREF>FIGS. 14-21</FGREF>.
<FGREF>FIGS. 9-10</FGREF>, illustrate exemplary block diagrams of the UWB scanning receiver 900 and its companion the UWB transmitter 1000. Time Domain Corporation has developed the UWB scanning receiver 900 that implements time-modulated ultra-wideband (TM-UWB) technology and utilizes short Gaussian monocycle pulses at relatively high pulse repetition frequencies (PRF). The pulse durations are less than 1 ns with a PRF exceeding 1 MHz. The interval between pulses is not fixed but is time coded using sequences of psuedo-random numbers. See, Withington, Reinhardt, and Stanley, “Preliminary Results of an Ultra-Wideband (Impulse) Scanning Receiver”, Paper S38P3, Milcom 1999, Atlantic City, N.J., November 1999 which is incorporated herein.
Referring to <FGREF>FIG. 11</FGREF>, there is illustrated a diagram of the basic components of the first embodiment of the intrusion detection system 1100. Basically, the intrusion detection system 1000 includes the UWB scanning receiver 900 and the UWB transmitter 1000 which together function as a bistatic radar to facilitate target detection. The introduction of any new object such as an intruder 1102 having an appreciable RCS into the environment alters the multipath structure of the protection zone 1104 and distorts the received scan waveform. The presence of the intruder 1102 is now detectable in the subtraction of successive scans; any significant change in a portion of this difference reveals the range of the intruder 1102 with respect to the placement of the UWB scanning receiver 900. Knowing the distance from the UWB transmitter 1000 to the UWB scanning receiver 900 and knowing the relative time delay of the target response in the scanned waveform, the position of the intruder 1102 is known to lie somewhere on an ellipse whose foci are the UWB transmitter 1000 and the UWB receiver 900. As illustrated, the intruder 1102 is located in one of two possible locations.
Empirical data has shown that for successive scans of an environment in which no intruder 1102 is present, limitations of the UWB scanning receiver 900 such as timer drift and small amplitude variations prevent successive scans from having perfect subtraction. This creates a certain clutter threshold in the subtracted waveform. The limitations of the UWB scanning receiver 900 require that the intruder 1102 introduced to the environment must reflect a return to the receive antenna 911 that is distinguishable from clutter. Effective filters and relevant thresholding techniques are used to combat this drift. Again, more details about the first embodiment of the intrusion detection system 1100 and various scanned waveforms are described below with respect to <FGREF>FIGS. 14-16</FGREF>.
Referring to <FGREF>FIG. 12</FGREF>, there is illustrated a block diagram of the basic components of the second embodiment of the intrusion detection system 1100′. The intrusion detection system 1100′ extends the functionality of the intrusion detection system 1100 by implementing multiple UWB scanning receivers 900′ (three shown) which can interact with the UWB transmitter 1000′ to triangulate the current position of the intruder 1102′. Coordinating the measured target ranges of multiple UWB scanning receivers 900′ can allow for precise positioning of the intruder 1102′ via an intersection of the ranging ellipses of known distance of the intruder 1102′ from each transmitter-receiver pair. This triangulation of the intruder 1102′ is graphically shown in FIG. 12.
Referring to <FGREF>FIG. 14</FGREF>, there is a diagram illustrating the first embodiment of the intrusion detection system 1100 in accordance with the present invention. The intrusion detection system 1100 includes a transmitting impulse radio unit 1000 (described above as the UWB transmitter 1000) and a receiving impulse radio unit 900 (described above as the UWB scanning receiver 900). The transmitting impulse radio unit 1000 transmits an impulse radio signal 1402 having a known pseudorandom sequence of pulses that look like a series of Gaussian waveforms (see FIG. 1).
Initially, the impulse radio signal 1402 is transmitted within and through a protection zone 1104 that does not have an intruder 1102. The receiving impulse radio unit 900 receives the impulse radio signal 1402 and generates a first waveform 1502 (an exemplary first waveform is shown in <FGREF>FIG. 15</FGREF>a). The first waveform 1502 is a time domain representation of the actual distortion of the transmitted Gaussian waveform after being filtered by the environment around the transmitting impulse radio unit 1000 and the receiving impulse radio unit 900. In other words, the first waveform 1502 corresponds to the received impulse shape of the impulse radio signal 1402 that is received by the receiving impulse radio unit 900 when there is no intruder 1102 located in the protection zone 1104.
After the generation of the first waveform 1502, the receiving impulse radio unit 900 receives at a subsequent time “t<HIL><SB>s</SB></HIL>” the impulse radio signal 1402 having a known pseudorandom sequence of pulses that are similar to the pulses initially transmitted by the transmitting impulse radio unit 1000 during the generation of the first waveform 1502. However at this time, the impulse radio signal 1402 is transmitted within and through a protection zone 1104 that does have an intruder 1102. In particular, the receiving impulse radio unit 900 receives the impulse radio signal 1402 that passed over a direct path 1404 between the transmitting impulse radio unit 1000 and the receiving impulse radio unit 900. The presence of the intruder 1102 causes the receiving impulse radio unit 900 to also receive the impulse radio signal 1402 that passed over an indirect path 1406 between the transmitting impulse radio unit 1000 and the receiving impulse radio unit 900. The receiving impulse radio unit 900 receives both of these impulse radio signals 1402 in addition to other reflected impulse radio signals 1402 (not shown) over time and generates a second waveform 1504 (an exemplary second waveform 1504 is shown in <FGREF>FIG. 15</FGREF>b). The second waveform 1504 is a time domain representation of the actual distortion of the transmitted Gaussian waveforms after being bounced of the intruder 1102 and filtered by the environment around the transmitting impulse radio unit 1000 and the receiving impulse radio unit 900. In other words, the second waveform 1504 corresponds to the received impulse shapes of the impulse radio signals 1402 that are received by the receiving impulse radio unit 900 when the intruder 1102 is located in the protection zone 1104.
The receiving impulse radio unit 900 includes a processor 1408 that compares the first waveform 1502 and the second waveform 1504 to determine whether there is a change between the first waveform 1502 and the second waveform 1504 caused by an intruder 1102 entering the protection zone 1104. To illustrate this change between waveforms reference is made to <FGREF>FIGS. 15</FGREF>a and 15b, where there are illustrated two exemplary waveforms 1502 and 1504 that could be generated by the receiving impulse radio unit 900. The first waveform 1502 has an initial wavefront 1503 representative of the first received impulse radio pulses of the impulse radio signal 1402. Likewise, the second waveform 1504 generated after the first waveform 1502 has an initial wavefront 1506 representative of the first received impulse radio pulse of the subsequently received impulse radio signal 1402. In addition, the second waveform 1504 has a multipath reflection part 1508 caused by the intruder 1102 that was absent in the first waveform 1502 but present in the second waveform 1504. This multipath reflection part 1508 is caused by the reception of the impulse radio signal 1402 that bounced off the intruder 1102 and passed over the indirect path 1406 between the transmitting impulse radio unit 1000 and the receiving impulse radio unit 900. The distance “d” between the intruder 1102 and the receiving impulse radio unit 900 can be calculated knowing the elapsed time “t” between the initial wavefront 1506 and the multipath reflection part 1508 of the second waveform 1504. Once the distance “d” is calculated, the intruder 1102 could be in one of many places indicated by the ellipse shown in <FGREF>FIG. 14</FGREF> (shown are two possible positions of the intruder 1102).
Referring to <FGREF>FIG. 16</FGREF>, there is a flowchart illustrating the basic steps of a first embodiment of the preferred method 1600 of the present invention. Beginning at step 1602, the transmitting impulse radio unit 1000 operates to transmit the impulse radio signal 1402. At this time, the impulse radio signal 1402 is made up of impulse radio pulses that are transmitted within and through a protection zone 1104 that does not have an intruder 1102. A more detailed discussion about the transmitting impulse radio unit 1000 has been provided above with respect to FIG. 10.
At step 1604, the receiving impulse radio unit 900 operates to receive the impulse radio signal 1402 and generate the first waveform 1502. Again, the receiving impulse radio unit 900 receives the impulse radio signal 1402 and generates a first waveform 1502 (see <FGREF>FIG. 15</FGREF>a) that is a time domain representation of the actual distortion of the transmitted Gaussian waveform after being filtered by the environment around the transmitting impulse radio unit 1000 and the receiving impulse radio unit 900. In other words, the first waveform 1502 corresponds to the received impulse shape of the impulse radio signal 1402 that is received by the receiving impulse radio unit 900 when there is no intruder 1102 located in the protection zone 1104. A more detailed discussion about the receiving impulse radio unit 1000 has been provided above with respect to FIG. 9.
At step 1606 and at a subsequent time with respect to steps 1602 and 1604, the receiving impulse radio unit 900 operates to receive the impulse radio signal 1402 and generate the second waveform 1504. In the present example, the second waveform 1504 (see <FGREF>FIG. 15</FGREF>b) illustrates what the impulse radio signals 1402 received by the receiving impulse radio unit 900 looks like in the time domain with an intruder 1102 located in the protection zone 1104. In other words, the second waveform 1504 corresponds to the received impulse shape of the impulse radio signals 1402 that are received by the receiving impulse radio unit 900 over the direct path 1404 and the indirect path 1406 when the intruder 1102 is located in the protection zone 1104.
At step 1608, the processor 1408 within the receiving impulse radio unit 900 operates to compare the first waveform 1502 and the second waveform 1504 to determine whether there is a change between the first waveform 1502 and the second waveform 1504 caused by an intruder 1102 entering the protection zone 1104. In the present example, there is a change between the first waveform 1502 and the second waveform 1504 because an intruder 1102 was not present when the first waveform 1502 was generated but the intruder 1102 was present when the second waveform 1504 was generated by the receiving impulse radio unit 900 (see <FGREF>FIGS. 15</FGREF>a-15b). This change is noticeable due to the presence of the multipath reflection part 1508 caused by the intruder 1102. Of course, the receiving impulse radio unit 900 may generate many second waveforms in which there is no difference or very little difference with a first waveform because an intruder 1102 was not present. If an intruder 1102 is not present in the protection zone 1104 then the method 1600 returns to and repeats steps 1606 and 1608 until an intruder 1102 is determined to be present in the protection zone 1104.
At step 1610, if the intruder 1102 is determined to be in the protection zone 1104, the processor 1408 could then calculate the difference “d” between the direct path between the transmitter 1000 and receiver 900 and the indirect path 1402 by knowing the elapsed time “t” between the initial wavefront 1506 and the multipath reflection part 1508 of the second waveform 1504 (see <FGREF>FIG. 15</FGREF>b). For instance, the distance “d” can be calculated to be 0.984 feet for each nanosecond in the elapsed time “t” between the initial wavefront 1506 and the multipath reflection part 1508 of the second waveform 1504 (see <FGREF>FIG. 15</FGREF>b). In this embodiment, the intruder 1102 could be in one of many places indicated by the ellipse shown in <FGREF>FIG. 14</FGREF> (shown are two possible positions of the intruder 1102). Reference is made to the second embodiment of the intrusion detection system 1100′ which can determine the real location of the intruder 1102.
Referring to <FGREF>FIG. 17</FGREF>, there is a diagram illustrating a second embodiment of the intrusion detection system 1100 in accordance with the present invention. The second embodiment of the intrusion detection system 1000 is illustrated using prime referenced numbers. Basically, the intrusion detection system 1000′ is the same as the first embodiment except that at least three receiving impulse radio units 900a′, 900b′ and 900c′ are used to enable a current position of the intruder 1102′ to be triangulated and determined within the protection zone 1104′. Each of the three receiving impulse radio units 900a′, 900b′ and 900c′ operate in a similar manner as the receiving impulse radio unit 900 of the first embodiment.
The intrusion detection system 1100′ includes a transmitting impulse radio unit 1000′ and at least three receiving impulse radio units 900a′, 900b′ and 900c′. The transmitting impulse radio unit 1000′ transmits an impulse radio signal 1402′ having a known pseudorandom sequence of pulses that look like a series of Gaussian waveforms (see FIG. 1). Initially, the impulse radio signal 1402′ is transmitted within and through a protection zone 1104′ that does not have an intruder 1102′.
Each receiving impulse radio unit 900a′, 900b′ and 900c′ respectively receives the first impulse radio signal 1402′ and generates a first waveform 1502a′, 1502b′ and 1502c′ (see <FGREF>FIG. 18</FGREF>a). The first waveform 1502a′, 1502b′ and 1502c′ is a time domain representation of the actual distortion of the transmitted Gaussian waveform after being filtered by the environment around the transmitting impulse radio unit 1000′ and each receiving impulse radio unit 900a′, 900b′ and 900c′. In other words, each first waveform 1502a′, 1502b′ and 1502c′ corresponds to the received impulse shape of the impulse radio signal 1402′ that is received by the receiving impulse radio units 900a′, 900b′ and 900c′ when there is no intruder 1102′ located in the protection zone 1104′.
After the generation of the first waveforms 1502a′, 1502b′and 1502c′, each receiving impulse radio unit 900a′, 900b′ and 900c′ receives at a subsequent time “t<HIL><SB>s</SB></HIL>” the impulse radio signal 1402′ having a known pseudorandom sequence of pulses that are similar to the pulses initially transmitted by the transmitting impulse radio unit 1000′ during the generation of the first waveforms 1502a′, 1502b′ and 1502c′. However at this time, the impulse radio signal 1402′ is transmitted within and through a protection zone 1104′ that does have an intruder 1102′.
In particular, each receiving impulse radio unit 900a′, 900b′ and 900c′ respectively receives the impulse radio signal 1402′ that passed over a direct path 1404a′, 1404b′ and 1404c′ between the transmitting impulse radio unit 1000′ and the receiving impulse radio units 900a′, 900b′ and 900c′. The presence of the intruder 1102′ causes each receiving impulse radio unit 900a′, 900b′ and 900c′ to also respectively receive the impulse radio signal 1402′ that passed over an indirect path 1406a′, 1406b′ and 1406c′ between the transmitting impulse radio unit 1000′ and the receiving impulse radio units 900a′, 900b′ and 900c′. Each receiving impulse radio unit 900a′, 900b′ and 900c′ receives both of these impulse radio signals 1402′ in addition to other reflected impulse radio signals 1402′ (not shown) over time and generates a second waveform 1504a′, 1504b′ and 1504c′ (see <FGREF>FIG. 18</FGREF>b). Each second waveform 1504a′, 1504b′ and 1504c′ is a time domain representation of the actual distortion of the transmitted Gaussian waveforms after being bounced of the intruder 1102′ and filtered by the environment around the transmitting impulse radio unit 1000′ and the receiving impulse radio units 900a′, 900b′ and 900c′. In other words, the second waveforms 1504a′, 1504b′ and 1504′ each correspond to the received impulse shapes of the impulse radio signals 1402′ that are received by each receiving impulse radio unit 900a′, 900b′ and 900c′ when the intruder 1102′ is located in the protection zone 1104′.
Each of the receiving impulse radio units 900a′, 900b′ and 900c′ includes a processor 1408′ that respectively compares the first waveform 1502a′, 1502b′ and 1502c′ and the second waveform 1504a′, 1504b′ and 1504c′ to determine whether there is a change between the first waveform 1502a′, 1502b′ and 1502c′ and the second waveform 1504a′, 1504b′ and 1504c′ caused by an intruder 1102′ entering the protection zone 1104′. To illustrate this change between waveforms reference is made to <FGREF>FIGS. 18</FGREF>a and 18b, where there are respectively illustrated exemplary first waveforms 1502a′, 1502b′, 1502c′ and exemplary second waveforms 1504a′, 1504b′ and 1504c′ that could be generated by the receiving impulse radio units 900a′, 900b′ and 900c′. For instance, the receiving impulse radio unit 900a′ would generate the first waveform 1502a′ and the second waveform 1504a′. Each first waveform 1502a′, 1502b′ and 1502c′ has an initial wavefront 1503a′, 1503b′ and 1503c′ representative of the first received impulse radio pulses of the impulse radio signal 1402′. Likewise, each second waveform 1504a′, 1504b′ and 1504c′ has an initial wavefront 1506a′, 1506b′ and 1506c′ representative of the first received impulse radio pulses in the subsequently received impulse radio signal 1402′. In addition, the second waveforms 1504a′, 1504b′ and 1504c′ each have a multipath reflection part 1508a′, 1508b′ and 1508c′ caused by the intruder 1102′ that was absent in the first waveforms 1502a′, 1502b′ and 1502c′ but present in the second waveforms 1504a′, 1504b′ and 1504c′. These multipath reflection parts 1508a′, 1508b′ and 1508c′ are caused by the reception of the impulse radio signals 1402′ that bounced off the intruder 1102′ and passed over the indirect path 1406a′, 1406b′ and 1406c′ between the transmitting impulse radio unit 1000 and the receiving impulse radio units 900a′, 900b′ and 900c′. The distances “d1”, “d2” and “d3” which are the differences between the direct paths 1402′ and indirect paths 1406a′, 1406b′ and 1406c′ can be calculated knowing the elapsed time “t1”, “t2” and “t3” between the initial wavefront 1506a′, 1506b′ and 1506c′ and the multipath reflection part 1508a′, 1508b′ and 1508c′ of the second waveforms 1504a′, 1504b′ and 1504c′.
Again it should be understood that there may be many items (e.g., walls, trees, furniture . . . ) within the protection zone 1104′ that could cause a multipath reflection part in the first waveform 1502a′, 1502b′ and 1502c′ and the second waveform 1504a′, 1504b′ and 1504c′ but it is the difference between the two waveforms that indicates the presence of one or more intruders 1102′. Moreover, it should be noted that the shape of the protection zone 1104′ in this embodiment is basically arbitrary as compared to the specially designed shape of the protection zone 1104″ the third embodiment.
After calculating the distances “d1”, “d2” and “d3” which are the differences between the direct paths 1402′ and indirect paths 1406a′, 1406b′ and 1406c′, each receiving impulse radio unit 900a′, 900b′ and 900c′ and transmitting unit 1000′ forwards their calculated distance “d1”, “d2” or “d3” to the transmitting impulse radio unit 1000′. Thereafter, the transmitting impulse radio unit 1000′ has a processor 1802′ that use the distances “d1”, “d2” and “d3”, and the known positions of the receiving impulse radio units 900a′, 900b′ and 900c′ to calculate the location of the intruder 1102′ within the protection zone 1104′. Again, the position of intruder 1102′ can be determined by the processor 1802′ using a numerical algorithm such as Newton-Raphson method or some other techniques. Once the position and coordinates of the intruder 1102′ are determined, various filtering techniques (e.g., Kalman filter) can be used by the intrusion detection system 1100′ to track the movement of the intruder 1102′ within the protection zone 1104′.
It should be understood that two receiving impulse radio units 900a′ and 900b′ could be used to calculate the position of the intruder 1102′ within the protection zone 1104′. This is possible in the situation where one of the three receiving impulse radio units 900a′, 900b′ or 900c′ can be eliminated if a part of the protection zone 1104′ is not required to be scanned and as such true triangulation of the position of the intruder 1102′ need not be performed.
Referring to <FGREF>FIGS. 19</FGREF>a-19b, there is a flowchart illustrating the basic steps of a second embodiment of the preferred method 1600′ of the present invention. Beginning at step 1902, the transmitting impulse radio unit 1000′ operates to transmit the impulse radio signal 1402′. At this time, the impulse radio signal 1402′ is made up of impulse radio pulses that are transmitted within and through a protection zone 1104′ that does not have an intruder 1102′.
At step 1904, the first receiving impulse radio unit 900a′ operates to receive the impulse radio signal 1402′ and generate the first waveform 1502a′. Again, the first receiving impulse radio unit 900a′ receives the impulse radio signal 1402′ and generates a first waveform 1502a′ (see <FGREF>FIG. 18</FGREF>a) that is a time domain representation of the actual distortion of the transmitted Gaussian waveform after being filtered by the environment around the transmitting impulse radio unit 1000′ and the receiving impulse radio units 900a′, 900b′ and 900c′. At this time, the first waveform 1502a′ corresponds to the received impulse shape of the impulse radio signal 1402′ that is received by the first receiving impulse radio unit 900a′ when there is no intruder 1102′ located in the protection zone 1104′.
At step 1906, the second receiving impulse radio unit 900b′ operates to receive the impulse radio signal 1402′ and generate the first waveform 1502b′. Again, the second receiving impulse radio unit 900b′ receives the impulse radio signal 1402′ and generates a first waveform 1502b′ (see <FGREF>FIG. 18</FGREF>a) that is a time domain representation of the actual distortion of the transmitted Gaussian waveform after being filtered by the environment around the transmitting impulse radio unit 1000′ and the receiving impulse radio units 900a′, 900b′ and 900c′. At this time, the first waveform 1502b′ corresponds to the received impulse shape of the impulse radio signal 1402′ that is received by the second receiving impulse radio unit 900b′ when there is no intruder 1102′ located in the protection zone 1104′.
At step 1908, the third receiving impulse radio unit 900c′ operates to receive the impulse radio signal 1402′ and generate the first waveform 1502c′. Again, the third receiving impulse radio unit 900c′ receives the impulse radio signal 1402′ and generates a first waveform 1502c′ (see <FGREF>FIG. 18</FGREF>a) that is a time domain representation of the actual distortion of the transmitted Gaussian waveform after being filtered by the environment around the transmitting impulse radio unit 1000′ and the receiving impulse radio units 900a′, 900b′ and 900c′. At this time, the first waveform 1502c′ corresponds to the received impulse shape of the impulse radio signal 1402′ that is received by the third receiving impulse radio unit 900c′ when there is no intruder 1102′ located in the protection zone 1104′. It should be understood that steps 1904, 1906 and 1908 can take place in any order depending on the locations of the receiving impulse radio units 900a′, 900b′ and 900c′ with respect to the location of the transmitting impulse radio unit 1000′.
At step 1910 and at a subsequent time with respect to step 1904, the first receiving impulse radio unit 900a′ operates to receive the impulse radio signal 1402′ and generate the second waveform 1504a′. In the present example, the second waveform 1504a′ (see <FGREF>FIG. 18</FGREF>b) illustrates what the impulse radio signals 1402′ received by the first receiving impulse radio unit 900a′ looks like in the time domain with an intruder 1102′ located in the protection zone 1104′. In other words, the second waveform 1502a′ corresponds to the received impulse shape of the impulse radio signals 1402′ that are received by the first receiving impulse radio unit 900a′ over the direct path 1404a′ and the indirect path 1406a′ when the intruder 1102′ is located in the protection zone 1104′.
At step 1912 and at a subsequent time with respect to step 1908, the second receiving impulse radio unit 900b′ operates to receive the impulse radio signal 1402′ and generate the second waveform 1504b′. In the present example, the second waveform 1504b′ (see <FGREF>FIG. 18</FGREF>b) illustrates what the impulse radio signals 1402′ received by the second receiving impulse radio unit 900b′ looks like in the time domain with an intruder 1102′ located in the protection zone 1104′. In other words, the second waveform 1502b′ corresponds to the received impulse shape of the impulse radio signals 1402′ that are received by the second receiving impulse radio unit 900b′ over the direct path 1404b′ and the indirect path 1406b′ when the intruder 1102′ is located in the protection zone 1104′.
At step 1914 and at a subsequent time with respect to step 2008, the third receiving impulse radio unit 900c′ operates to receive the impulse radio signal 1402′ and generate the second waveform 1504c′. In the present example, the second waveform 1504c′ (see <FGREF>FIG. 18</FGREF>b) illustrates what the impulse radio signals 1402′ received by the third receiving impulse radio unit 900c′ looks like in the time domain with an intruder 1102′ located in the protection zone 1104′. In other words, the second waveform 1502c′ corresponds to the received impulse shape of the impulse radio signals 1402′ that are received by the third receiving impulse radio unit 900c′ over the direct path 1404c′ and the indirect path 1406c′ when the intruder 1102′ is located in the protection zone 1104′. It should be understood that steps 1910, 1912 and 1914 can take place in any order depending on the locations of the receiving impulse radio units 900a′, 900b′ and 900c′ with respect to the location of the transmitting impulse radio unit 1000′.
At step 1916, the processor 1408a′ within the first receiving impulse radio unit 900a′ operates to compare the first waveform 1502a′ and the second waveform 1504a′ to determine whether there is a change between the first waveform 1502a′ and the second waveform 1504a′ caused by an intruder 1102′ entering the protection zone 1104′. In the present example, there is a change between the first waveform 1502a′ and the second waveform 1504a′ because an intruder 1102′ was not present when the first waveform 1502a′ was generated but the intruder 1102′ was present when the second waveform 1504a′ was generated by the first receiving impulse radio unit 900a′ (see <FGREF>FIGS. 18</FGREF>a-18b). This change is noticeable due to the presence of the multipath reflection part 1508a′ caused by the intruder 1102′. Of course, the first receiving impulse radio unit 900a′ may generate many second waveforms at step 1910 in which there is no difference or very little difference with a first waveform because an intruder 1102′ was not present. If an intruder 1102′ is not present in the protection zone 1104′ then the method 1600′ returns to and repeats steps 1910 and 1916 until an intruder 1102′ is determined to be present in the protection zone 1104′.
At step 1918, if the intruder 1102′ is determined to be in the protection zone 1104′, the processor 1408a′ could then calculate the distance “d1” between direct and indirect paths by knowing the elapsed time “t1” between the initial wavefront 1506a′ and the multipath reflection part 1508a′ of the second waveform 1504a′ (see <FGREF>FIG. 18</FGREF>b). For instance, the distance “d1” can be calculated to be 0.984 feet for each nanosecond in the elapsed time “t1” between the initial wavefront 1506a′ and the multipath reflection part 1508a′ of the second waveform 1504a′(see <FGREF>FIG. 18</FGREF>b).
At step 1920, the processor 1408b′ within the second receiving impulse radio unit 900b′ operates to compare the first waveform 1502b′ and the second waveform 1504b′ to determine whether there is a change between the first waveform 1502b′ and the second waveform 1504b′ caused by an intruder 1102′ entering the protection zone 1104′. In the present example, there is a change between the first waveform 1502b′ and the second waveform 1504b′ because an intruder 1102′ was not present when the first waveform 1502b′ was generated but the intruder 1102′ was present when the second waveform 1504b′ was generated by the second receiving impulse radio unit 900b′ (see <FGREF>FIGS. 18</FGREF>a-18b). This change is noticeable due to the presence of the multipath reflection part 1508b′ caused by the intruder 1102′. Of course, the second receiving impulse radio unit 900b′ may generate many second waveforms at step 1912 in which there is no difference or very little difference with a first waveform because an intruder 1102′ was not present. If an intruder 1102′ is not present in the protection zone 1104′ then the method 1600′ returns to and repeats steps 1912 and 1920 until an intruder 1102′ is determined to be present in the protection zone 1104′.
At step 1922, if the intruder 1102′ is determined to be in the protection zone 1104′, the processor 1408b′ could then calculate the distance “d2” between direct and indirect paths by knowing the elapsed time “t2” between the initial wavefront 1506b′ and the multipath reflection part 1508b′ of the second waveform 1504b′ (see <FGREF>FIG. 18</FGREF>b). For instance, the distance “d2” can be calculated to be 0.984 feet for each nanosecond in the elapsed time “t2” between the initial wavefront 1506b′ and the multipath reflection part 1508b′ of the second waveform 1504b′ (see <FGREF>FIG. 18</FGREF>b).
At step 1924, the processor 1408c′ within the third receiving impulse radio unit 900c′ operates to compare the first waveform 1502c′ and the second waveform 1504c′ to determine whether there is a change between the first waveform 1502c′ and the second waveform 1504c′ caused by an intruder 1102′ entering the protection zone 1104′. In the present example, there is a change between the first waveform 1502c′ and the second waveform 1504c′ because an intruder 1102′ was not present when the first waveform 1502c′ was generated but the intruder 1102′ was present when the second waveform 1504c′ was generated by the third receiving impulse radio unit 900c′ (see <FGREF>FIGS. 18</FGREF>a-18b). This change is noticeable due to the presence of the multipath reflection part 1508c′ caused by the intruder 1102′. Of course, the third receiving impulse radio unit 900c′ may generate many second waveforms at step 1914 in which there is no difference or very little difference with a first waveform because an intruder 1102′ was not present. If an intruder 1102′ is not present in the protection zone 1104′ then the method 1600′ returns to and repeats steps 1914 and 1924 until an intruder 1102′ is determined to be present in the protection zone 1104′.
At step 1926, if the intruder 1102′ is determined to be in the protection zone 1104′, the processor 1408c′ could then calculate the distance “d3” between direct and indirect paths by knowing the elapsed time “t3” between the initial wavefront 1506c′ and the multipath reflection part 1508c′ of the second waveform 1504c′ (see <FGREF>FIG. 18</FGREF>b). For instance, the distance “d3” can be calculated to be 0.984 feet for each nanosecond in the elapsed time “t3” between the initial wavefront 1506c′ and the multipath reflection part 1508c′ of the second waveform 1504c′ (see <FGREF>FIG. 18</FGREF>b).
At step 1928, after calculating the distances “d1”, “d2” and “d3” between each receiving impulse radio unit 900a′, 900b′ and 900c′ and the intruder 1102′, each receiving impulse radio unit 900a′, 900b′ and 900c′ forwards their calculated distance “d1”, “d2” or “d3” to the transmitting impulse radio unit 1000′.
At step 1930, the transmitting impulse radio unit 1000′ has a processor 1802′ that use the distances “d1”, “d2” and “d3” and the known positions of the receiving impulse radio units 900a′, 900b′ and 900c′ to calculate the location of the intruder 1102′ within the protection zone 1104′. Again, the position of intruder 1102′ can be determined by the processor 1802′ using a numerical algorithm such as Newton-Raphson method or some other techniques.
Referring to <FGREF>FIG. 20</FGREF>, there is a diagram illustrating a third embodiment of the intrusion detection system 1100 in accordance with the present invention. The third embodiment of the intrusion detection system 1100 is illustrated using double prime referenced numbers. Basically, the intrusion detection system 1100″ is similar to the second embodiment except that prior to detecting any intruders 1102″ the intrusion detection system 1100″ can utilize a test subject 2002″ and impulse radio technology to design the shape of the protection zone 1104″. In other words, the intrusion detection system 1100″ enables the creation of an unusually shaped protection zone 1104c″ instead of using the arbitrary shapes associated with the protection zones 1104 and 1104′ of the first two embodiments. Prior to arming the intrusion detection system 1100′, the system can be put into a “learning mode”. During the “learning mode”, the test subject 2002″ traverses the perimeter 2204″ of the protection zone 1104c″ to be protected and the intrusion detection system 1100″ would track the test subject 2002″ and build a two and possibly three-dimensional representation of the shape of the protection zone 1104c″.The intrusion detection system 1100″ can track the test subject 2002″ in the same manner the intrusion detection system 1100′ would track an intruder 1104′ in the second embodiment.
Like the second embodiment, the intrusion detection system 1100″ includes a transmitting impulse radio unit 1000″ and at least three receiving impulse radio units 900a″, 900b″ and 900c″. The transmitting impulse radio unit 1000″ transmits an impulse radio signal 1402″ having a known pseudorandom sequence of pulses that look like a series of Gaussian waveforms (see FIG. 1). Initially, the impulse radio signal 1402″ is transmitted within and through an area including the protection zone 1104c″ that does not have an intruder 1102″.
Each receiving impulse radio unit 900a″, 900b″ and 900c″ receives the first impulse radio signal 1402″ and generates a first waveform 1502a″, 1502b″ and 1502c″ (similar to the first waveforms 1502a′, 1502b′ and 1502c′ shown in <FGREF>FIG. 18</FGREF>a). Each of the first waveforms 1502a″, 1502b″ and 1502c″ is a time domain representation of the actual distortion of the transmitted Gaussian waveform after being filtered by the environment around the transmitting impulse radio unit 1000″ and each receiving impulse radio unit 900a″, 900b″ and 900c″. In other words, each first waveform 1502a″, 1502b″ and 1502c″ corresponds to the received impulse shape of the impulse radio signal 1402″ that is received by each receiving impulse radio unit 900a″, 900b″ and 900c″ when there is no intruder 1102″ located in or near the protection zone 1104c″.
After the generation of the first waveforms 1502a″, 1502b″ and 1502c″, each receiving impulse radio unit 900a″, 900b″ and 900c″ receives at a subsequent time “t<HIL><SB>s</SB></HIL>” the impulse radio signal 1402″ having a known pseudorandom sequence of pulses that are similar to the pulses initially transmitted by the transmitting impulse radio unit 1000″ during the generation of the first waveforms 1502a″, 1502b″ and 1502c″. However at this time, the impulse radio signal 1402″ is transmitted within and through a protection zone 1104c″ that does have an intruder 1102″ in or near it.
In particular, each receiving impulse radio unit 900a″, 900b″ and 900c″ respectively receives the impulse radio signal 1402″ that passed over a direct path 1404a″, 1404b″ and 1404c″ between the transmitting impulse radio unit 1000″ and the receiving impulse radio unit 900a″, 900b″ and 900c″. The presence of the intruder 1102″ causes each receiving impulse radio unit 900a″, 900b″ and 900c″ to also respectively receive the impulse radio signal 1402″ that passed over an indirect path 1406a″, 1406b″ and 1406c″ from the transmitting impulse radio unit 1000″ to the receiving impulse radio unit 900a″, 900b″ and 900c″. Each receiving impulse radio unit 900a″, 900b″ and 900c″ receives both of these impulse radio signals 1402″ in addition to other reflected impulse radio signals 1402″ (not shown) over time and generates a second waveform 1504a″, 1504b″ and 1504c″ (similar to the second waveforms 1504a′, 1504b′ and 1504c′ shown in <FGREF>FIG. 18</FGREF>b). Each second waveform 1504a″, 1504b″ and 1504c″ is a time domain representation of the actual distortion of the transmitted Gaussian waveforms after being bounced of the intruder 1102″ and filtered by the environment around the transmitting impulse radio unit 1000″ and the receiving impulse radio units 900a″, 900b″ and 900c″. In other words, the second waveforms 1504a″, 1504b″ and 1504c″ each correspond to the received impulse shapes of the impulse radio signals 1402″ that are received by each receiving impulse radio unit 900a″, 900b″ and 900c″ when the intruder 1102″ is located in or near the protection zone 1104c″. A determination as to whether the intruder 1104″ is actually inside the specially shaped protection zone 1104c″ is made later by the processor 1802″ associated with the transmitting impulse radio unit 1000″.
Each of the receiving impulse radio units 900a″, 900b″ and 900c″ includes a processor 1408″ that compares the first waveform 1502a″, 1502b″ and 1502c″ and the second waveform 1504a″, 1504b″ and 1504c″ to determine whether there is a change between the first waveform 1502a″, 1502b″ and 1502c″ and the second waveform 1504a″, 1504b″ and 1504c″ caused by an intruder 1102″ entering or coming near the protection zone 1104c″. Like the first waveforms 1502a′, 1502b′ and 1502c′ and the second waveforms 1504a′, 1504b′ and 1504c′ shown in <FGREF>FIGS. 19</FGREF>a and 19b, each first waveform 1502a″, 1502b″ and 1502c″ has an initial wavefront 1503a″, 1503b″ and 1503c″ representative of the first received impulse radio pulses of the impulse radio signal 1402″. Likewise, each second waveform 1504a″, 1504b″ and 1504c″ has an initial wavefront 1506a″, 1506b″ and 1506c″ representative of the first received impulse radio pulses in the subsequently received impulse radio signal 1402″. In addition, the second waveforms 1504a″, 1504b″ and 1504c″ each have a multipath reflection part 1508a″, 1508b″ and 1508c″ caused by the intruder 1102″ that was absent in the first waveforms 1502a″, 1502b″ and 1502c″ but present in the second waveforms 1504a″, 1504b″ and 1504c″. These multipath reflection parts 1508a″, 1508b″ and 1508c″ are caused by the reception of the impulse radio signals 1402″ that bounced off the intruder 1102″ and passed over the indirect path 1406a″, 1406b″ and 1406c″ between the transmitting impulse radio unit 1000″ and the receiving impulse radio units 900a″, 900b″ and 900c″. The distances “d1”, “d2” and “d3” between direct and indirect paths can be calculated knowing the elapsed time “t1”, “t2” and “t3” between the initial wavefront 1506a″, 1506b″ and 1506c″ of the second waveforms 1504a″, 1504b″ and 1504c″ and the multipath reflection part 1508a″, 1508b″ and 1508c″. Again, a determination as to whether the intruder 1104″ is actually inside the specially shaped protection zone 1104c″ is made later by the processor 1802″ associated with the transmitting impulse radio unit 1000″.
It should be understood that there may be many items (e.g., walls, trees, furniture . . . ) within or near the protection zone 1104c″ that could cause a multipath reflection part in the first waveform 1502a″, 1502b″ and 1502c″ and the second waveforms 1504a″, 1504b″ and 1504c″ but it is the difference between the two waveforms that indicates the presence of one or more intruders 1102″.
After calculating the distances “d1”, “d2” and “d3” between direct and indirect paths, each receiving impulse radio unit 900a″, 900b″ and 900c″ forwards their calculated distance “d1”, “d2” or “d3” to the transmitting impulse radio unit 1000″. Thereafter, the transmitting impulse radio unit 1000″ has a processor 1802″ that use the distances “d1”, “d2” and “d3” and the known positions of the receiving impulse radio units 900a″, 900b″ and 900c″ to calculate the location within or near the protection zone 1104c″ of the intruder 1102″.
To do determine whether the intruder 1102″ is actually within the protection zone 1104c″ (as shown) or just near the protection zone 1104c″, the processor 1802″ would determine the location of the intruder 1102″ and then compare this location to the two and possibly three-dimensional representation of the shape of the protection zone 1104c″. Again, the position of intruder 1102″ can be determined by the processor 1802″ using a numerical algorithm such as Newton-Raphson method or some other techniques. Once the position and coordinates of the intruder 1102″ are determined, various filtering techniques (e.g., Kalman filter) can be used by the intrusion detection system 1100″ to track the movement of the intruder 1102″ within the protection zone 1104c″.
Referring to <FGREF>FIGS. 21</FGREF>a-21b, there is a flowchart illustrating the basic steps of a third embodiment of the preferred method 1600″ of the present invention. Beginning at step 2101, prior to arming the intrusion detection system 1100″, the system is put into a “learning mode”. During the “learning mode”, the test subject 2002″ traverses the perimeter 2204″ of the protection zone 1104c″ to be protected and the intrusion detection system 1100″ would track the test subject 2002″ and build a two and possibly three-dimensional representation of the shape of the protection zone 1104c″. The intrusion detection system 1100″ can track the test subject 2002″ in the same manner the intrusion detection system 1100′ would track an intruder 1104′ in the second embodiment.
At step 2102, after creating the shape of the protection zone 1104c″, the transmitting impulse radio unit 1000″ operates to transmit the impulse radio signal 1402″. At this time, the impulse radio signal 1402″ is made up of impulse radio pulses that are transmitted within and through a protection zone 1104c″ that does not have an intruder 1102″.
At step 2104, the first receiving impulse radio unit 900a″ operates to receive the impulse radio signal 1402″ and generate the first waveform 1502a″. Again, the first receiving impulse radio unit 900a″ receives the impulse radio signal 1402″ and generates a first waveform 1502a″ (e.g., see first waveform 1502a′ in <FGREF>FIG. 19</FGREF>a) that is a time domain representation of the actual distortion of the transmitted Gaussian waveform after being filtered by the environment around the transmitting impulse radio unit 1000″ and the receiving impulse radio units 900a″, 900b″ and 900c″. At this time, the first waveform 1502a″ corresponds to the received impulse shape of the impulse radio signal 1402″ that is received by the first receiving impulse radio unit 900a″ when there is no intruder 1102″ located in or near the protection zone 1104c″.
At step 2106, the second receiving impulse radio unit 900b″ operates to receive the impulse radio signal 1402″ and generate the first waveform 1502b″. Again, the second receiving impulse radio unit 900b″ receives the impulse radio signal 1402″ and generates a first waveform 1502b″ (e.g., see first waveform 1502b′ in <FGREF>FIG. 18</FGREF>a) that is a time domain representation of the actual distortion of the transmitted Gaussian waveform after being filtered by the environment around the transmitting impulse radio unit 1000″ and the receiving impulse radio units 900a″, 900b″ and 900c″. At this time, the first waveform 1502b″ corresponds to the received impulse shape of the impulse radio signal 1402″ that is received by the second receiving impulse radio unit 900b″ when there is no intruder 1102″ located in or near the protection zone 1104c″.
At step 2108, the third receiving impulse radio unit 900c″ operates to receive the impulse radio signal 1402″ and generate the first waveform 1502c″. Again, the third receiving impulse radio unit 900c″ receives the impulse radio signal 1402″ and generates a first waveform 1502c″ (e.g., see first waveform 1502c′ in <FGREF>FIG. 18</FGREF>a) that is a time domain representation of the actual distortion of the transmitted Gaussian waveform after being filtered by the environment around the transmitting impulse radio unit 1000″ and the receiving impulse radio units 900a″, 900b″ and 900c″. At this time, the first waveform 1502c″ corresponds to the received impulse shape of the impulse radio signal 1402″ that is received by the third receiving impulse radio unit 900c″ when there is no intruder 1102″ located in or near the protection zone 1104c″. It should be understood that steps 2104, 2106 and 2108 can take place in any order depending on the locations of the receiving impulse radio units 900a″, 900b″ and 900c″ with respect to the location of the transmitting impulse radio unit 1000″.
At step 2110 and at a subsequent time with respect to step 2304, the first receiving impulse radio unit 900a″ operates to receive the impulse radio signal 1402″ and generate the second waveform 1504a″. In the present example, the second waveform 1504a″ (e.g., see second waveform 1504a′ in <FGREF>FIG. 18</FGREF>b) illustrates what the impulse radio signals 1402″ received by the first receiving impulse radio unit 900a″ looks like in the time domain with an intruder 1102″ located in or near the protection zone 1104c″. In other words, the second waveform 1502a″ corresponds to the received impulse shape of the impulse radio signals 1402″ that are received by the first receiving impulse radio unit 900a″ over the direct path 1404a″ and the indirect path 1406a″ when the intruder 1102″ is located in or near the protection zone 1104c″. A determination as to whether the intruder 1104″ is actually inside the specially shaped protection zone 1104c″ is made later at step 2030 by the processor 1802″ associated with the transmitting impulse radio unit 1000″.
At step 2112 and at a subsequent time with respect to step 2308, the second receiving impulse radio unit 900b″ operates to receive the impulse radio signal 1402″ and generate the second waveform 1504b″. In the present example, the second waveform 1504b″ (e.g., see second waveform 1504b′ in <FGREF>FIG. 18</FGREF>b) illustrates what the impulse radio signals 1402″ received by the second receiving impulse radio unit 900b″ looks like in the time domain with an intruder 1102″ located in or near the protection zone 1104c″. In other words, the second waveform 1502b″ corresponds to the received impulse shape of the impulse radio signals 1402″ that are received by the second receiving impulse radio unit 900b″ over the direct path 1404b″ and the indirect path 1406b″ when the intruder 1102″ is located in or near the protection zone 1104c″. Again, a determination as to whether the intruder 1104″ is actually inside the specially shaped protection zone 1104c″ is made later at step 2130 by the processor 1802″ associated with the transmitting impulse radio unit 1000″.
At step 2114 and at a subsequent time with respect to step 2108, the third receiving impulse radio unit 900c″ operates to receive the impulse radio signal 1402″ and generate the second waveform 1504c″. In the present example, the second waveform 1504c″ (e.g., see second waveform 1504c′ in <FGREF>FIG. 18</FGREF>b) illustrates what the impulse radio signals 1402″ received by the third receiving impulse radio unit 900c″ looks like in the time domain with an intruder 1102″ located in or near the protection zone 1104c″ . In other words, the second waveform 1502c″ corresponds to the received impulse shape of the impulse radio signals 1402″ that are received by the third receiving impulse radio unit 900c″ over the direct path 1404c″ and the indirect path 1406c″ when the intruder 1102″ is located in or near the protection zone 1104c″. Again, a determination as to whether the intruder 1104″ is actually inside the specially shaped protection zone 1104c″ is made later at step 2030 by the processor 1802″ associated with the transmitting impulse radio unit 1000″. It should be understood that steps 2110, 2112 and 2114 can take place in any order depending on the locations of the receiving impulse radio units 900a″, 900b″ and 900c″ with respect to the location of the transmitting impulse radio unit 1000″.
At step 2116, the processor 1408a″ within the first receiving impulse radio unit 900a″ operates to compare the first waveform 1502a″ and the second waveform 1504a″ to determine whether there is a change between the first waveform 1502a″ and the second waveform 1504a″ caused by an intruder 1102″ coming near or entering the protection zone 1104c″. In the present example, there is a change between the first waveform 1502a″ and the second waveform 1504a″ because an intruder 1102″ was not present when the first waveform 1502a″ was generated but the intruder 1102″ was present when the second waveform 1504a″ was generated by the first receiving impulse radio unit 900a″ (e.g., see first waveform 1502a′ and second waveform 1504a′ in <FGREF>FIGS. 18</FGREF>a-18b). This change is noticeable due to the presence of the multipath reflection part 1508a″ caused by the intruder 1102″. Of course, the first receiving impulse radio unit 900a″ may generate many second waveforms at step 2110 in which there is no difference or very little difference with a first waveform because an intruder 1102″ was not present. If an intruder 1102″ is not within or near the protection zone 1104c″ then the method 1600″ returns to and repeats steps 2110 and 2116 until an intruder 1102″ is determined to be within or near the protection zone 1104c″.
At step 2118, if the intruder 1102″ is determined to be within or near the protection zone 1104c″, the processor 1408a″ could then calculate the distance “d1” between direct and indirect paths by knowing the elapsed time “t1” between the initial wavefront 1506a″ and the multipath reflection part 1508a″ of the second waveform 1504a″ (e.g., see second waveform 1504a′ in <FGREF>FIG. 18</FGREF>b). For instance, the distance “d1” can be calculated to be 0.984 feet for each nanosecond in the elapsed time “t1” between the initial wavefront 1506a″ and the multipath reflection part 1508a″ of the second waveform 1504a″ (e.g., see second waveform 1504a′ in <FGREF>FIG. 18</FGREF>b). Again, a determination as to whether the intruder 1104″ is actually inside the specially shaped protection zone 1104c″ is made later at step 2130 by the processor 1802″ associated with the transmitting impulse radio unit 1000″.
At step 2120, the processor 1408b″ within the second receiving impulse radio unit 900b″ operates to compare the first waveform 1502b″ and the second waveform 1504b″ to determine whether there is a change between the first waveform 1502b″ and the second waveform 1504b″ caused by an intruder 1102″ coming near or entering the protection zone 1104c″. In the present example, there is a change between the first waveform 1502b″ and the second waveform 1504b″ because an intruder 1102″ was not present when the first waveform 1502b″ was generated but the intruder 1102″ was present when the second waveform 1504b″ was generated by the second receiving impulse radio unit 900b″ (e.g., see first waveform 1502b′ and second waveform 1504b′ in <FGREF>FIGS. 18</FGREF>a-18b). This change is noticeable due to the presence of the multipath reflection part 1508b″ caused by the intruder 1102″. Of course, the second receiving impulse radio unit 900b″ may generate many second waveforms at step 2112 in which there is no difference or very little difference with a first waveform because an intruder 1102″ was not present. If an intruder 1102″ is not within or near the protection zone 1104c″ then the method 1600″ returns to and repeats steps 2112 and 2120 until an intruder 1102″ is determined to be within or near the protection zone 1104c″.
At step 2122, if the intruder 1102″ is determined to be within or near the protection zone 1104c″, the processor 1408b″ could then calculate the distance “d2” between direct and indirect paths by knowing the elapsed time “t2”, between the initial wavefront 1506b″ and the multipath reflection part 1508b″ of the second waveform 1504b″ (e.g., see second waveform 1504b′ in <FGREF>FIG. 18</FGREF>b). For instance, the distance “d2” can be calculated to be 0.984 feet for each nanosecond in the elapsed time “t2” between the initial wavefront 1506b″ and the multipath reflection part 1508b″ of the second waveform 1504b″ (e.g., see second waveform 1504b′ in <FGREF>FIG. 18</FGREF>b). Again, a determination as to whether the intruder 1104″ is actually inside the specially shaped protection zone 1104c″ is made later at step 2030 by the processor 1802″ associated with the transmitting impulse radio unit 1000″.
At step 2124, the processor 1408c″ within the third receiving impulse radio unit 900c″ operates to compare the first waveform 1502c″ and the second waveform 1504c″ to determine whether there is a change between the first waveform 1502c″ and the second waveform 1504c″ caused by an intruder 1102″ coming near or entering the protection zone 1104c″. In the present example, there is a change between the first waveform 1502c″ and the second waveform 1504c″ because an intruder 1102″ was not present when the first waveform 1502c″ was generated but the intruder 1102″ was present when the second waveform 1504c″ was generated by the third receiving impulse radio unit 900c″ (e.g., see first waveform 1502c′ and second waveform 1504c′ in <FGREF>FIGS. 18</FGREF>a-18b). This change is noticeable due to the presence of the multipath reflection part 1508c″ caused by the intruder 1102″. Of course, the third receiving impulse radio unit 900c″ may generate many second waveforms at step 2314 in which there is no difference or very little difference with a first waveform because an intruder 1102″ was not present. If an intruder 1102″ is not within or near the protection zone 1104c″ then the method 1600″ returns to and repeats steps 2114 and 2124 until an intruder 1102″ is determined to be within or near the protection zone 1104c″.
At step 2126, if the intruder 1102″ is determined to be within or near the protection zone 1104c″, the processor 1408c″ could then calculate the distance “d3” between direct and indirect paths by knowing the elapsed time “t3” between the initial wavefront 1506c″ and the multipath reflection part 1508c″ of the second waveform 1504c″ (e.g., see second waveform 1504c′ in <FGREF>FIG. 18</FGREF>b). For instance, the distance “d3” can be calculated to be 0.984 feet for each nanosecond in the elapsed time “t3” between the initial wavefront 1506c″ and the multipath reflection part 1508c″ of the second waveform 1504c″ (e.g., see second waveform 1504c′ in <FGREF>FIG. 18</FGREF>b). Again, a determination as to whether the intruder 1104″ is actually inside the specially shaped protection zone 1104c″ is made later at step 2030 by the processor 1802″ associated with the transmitting impulse radio unit 1000″.
At step 2128, after calculating the distances “d1”, “d2” and “d3” between direct and indirect paths, each receiving impulse radio unit 900a″, 900b″ and 900c″ forwards their calculated distance “d1”, “d2” or “d3” to the transmitting impulse radio unit 1000″.
At step 2130, the transmitting impulse radio unit 1000″ has a processor 1802″ that use the distances “d1”, “d2” and “d3” and the known positions of the receiving impulse radio units 900a″, 900b″ and 900c″ to calculate the location of the intruder 1102″ within or near the protection zone 1104c″. To determine whether the intruder 1102′ is actually within the protection zone 1104c″ or just near the protection zone 1104c″, the processor 1802″ would determine the location of the intruder 1102″ and then compare this location to the two and possibly three-dimensional representation of the shape of the protection zone 1104c″. Again, the position of intruder 1102″ can be determined by the processor 1802″ using a numerical algorithm such as Newton-Raphson method or some other techniques.
At step 2132, once the position and coordinates of the intruder 1102″ are determined at step 2130, then various filtering techniques (e.g., Kalman filter) can be used by the intrusion detection system 1100″ to track the movement of the intruder 1102″ within the protection zone 1104c″.
At step 2134, the intrusion detection system 1100″ sounds an alarm and/or informs remote security personnel when there is an intruder 1102″ located within (or near) the protection zone 1104c″. For extra security, the intrusion detection system 1100″ can use impulse radio technology to alert the remote security personnel.
Referring to <FGREF>FIG. 22</FGREF>, there is illustrated a diagram of the intrusion detection system 1100, 1100′ and 1100″ that uses one or more directive antennas 2202. As shown, the transmitting impulse radio unit 1000, 1000′ and 1000″ (only one shown) can use the directive antenna 2202 (only one shown) to transmit the impulse radio signal in a predetermined direction such that radar is sensitive in a particular area 2204 (see solid line) and not sensitive in another area 2206 (see dashed line). In particular, the intrusion detection system 1100, 1100′ and 1100″ that uses an directive antenna 2202 can make the radar sensitive in a particular area 2204 to detect a person 2208 or a dangerous animal 2210 that is not supposed to be located in that area 2204 and at the same time the directive antenna 2202 does not make the radar sensitive in another area 2206 in which the dangerous animal 2210 is suppose to be located. It should be understood that the directive antenna 2202 can take many different forms including, for example, a 180° directive antenna and a 90° directive antenna. Moreover, it should also be understood that a directional antenna 2202 could be placed at the receiving impulse radio unit 900, 900′ and 900″ or at both the receiving and transmitting impulse radio units.
Hall, David J., Yano, Scott M., Schantz, Hans G.
US 20020130807A1
342/27, 342/28, 342/52, 342/53, 342/54, 342/55, 342/56, 342/57, 342/58, 342/59, 342/73, 342/89, 342/90, 342/118, 342/134, 342/135-146, 342/175, 342/195, 342/21, 342/450-458, 342/461-465, 342/125-133, 375/130-153
G08B 13/187 : by interference of a radiat...