ITMI20062433A1 - PROCEDURE AND DEVICE FOR PROCESSING SIGNALS DURING THE DETERMINATION OF THE ANGLE BY MEANS OF MICROWAVE MOVEMENT SENSORS - Google Patents

Description

JAUMANN PATENT STUDY

by Jaumann P. & C. Sas

Via San Giovanni sul Muro, 13

20121 MILAN

Company: ROBERT BOSCH GMBH

Headquarters: S taparda (Germany)

DESCRIPTION

The present invention generally relates to a process and a signal processing device for determining the angle using microwaves. In particular, the present invention relates to a device for detecting an angle of incidence of an electromagnetic wave radiated by a transmitter towards a target, according to a primary diffusion direction. For the reception of the electromagnetic wave at least two receiving units are envisaged, which receive 1 <1> electromagnetic wave returned by the target and convert it into at least one intermediate frequency signal. Said intermediate frequency signal is transformed by means of a converter into at least a first and a second detection signal, evaluating an analyzer of said first and second detection signals in such a way as to obtain the angle of incidence of the electromagnetic wave. with respect to the primary diffusion direction of the transmitter, and therefore, an angular position of the target with respect to 11 ^

/

ww / w

primary diffusion direction of the transmitter.

State of the art

As shown for example in Fig. 1, motion sensors for detecting people or their movements have a combination of microwave sensors and PIR (passive infrared) sensors. In these cases the device with microwave sensors has a high frequency source, which normally delivers a 0 signal in continuous wave. The high frequency source is represented by an OSZ oscillator, which normally works in the GHz range. The high frequency 0 signal is conducted to a splitter A which generates on the one hand a transmission signal Tx and on the other sends to a mixer M a local oscillator 0 signal to mix a receive signal Rx. The reception signal Rx mixed with the signal of the local oscillator 0 is sent by the mixer M to an analyzer AE in the form of an intermediate frequency signal ZF, possibly with components in phase and in quadrature. The received signal Rx obtained as a function of the transmitted signal Tx can show a Doppler shift as a function of the movements to a target Z. In Fig. I the movements are represented by the velocity components v-anger.z-.aiee va iale · In addition, target Z absorbs an infrared IR beam by means of a PIR infrared sensor. The AE analyzer then also receives a corresponding PIR signal, and by a common process combines the signals received from the microwave components with those from the infrared part to output an AS alarm signal.

Microwave sensors are often made in such a way that they can take advantage of the Doppler effect. In the simplest case, these sensors are built with a high frequency source in continuous wave (CW, Continuous Wave), whose output signal is shared between a first antenna, the emitting antenna and the input of the local oscillator (LO In many cases it is possible to deactivate the source in continuous wave, so as to obtain periods of inactivity in the operation of the sensor. The signal of a second antenna, the so-called receiving antenna, is conducted to the signal input of the mixer. A corresponding doppler signal is available on the output of the mixer. The doppler frequency Af of the doppler signal to send back to the sensor system a signal emitted by a sensor system at rest towards a moving object is determined with the equation:

\ l = 2 v f / c

where c = speed of light, f = frequency of the transmission signal (usually 10 GHz) and v - speed of the target (a positive value in this case indicates a movement towards the sensor system, a negative value instead a departure from the system) . The target speed is usually between 0.1 and 3 m / s (0.36 to 10.8 km / h), which gives a Doppler frequency between 6.7 and 200 Hz. To recognize the direction of movement (towards the sensors or in the opposite direction) it is necessary to be able to detect the components in phase and in quadrature, known to those skilled in the art, of the mixed product. For this purpose, a so-called I / Q mixer is used, which makes it possible to use a "single sideband" signal processing from which the sign of the doppler frequency is extrapolated.

In the case of digitized analysis, a Fourier transformation occurs in a digital analyzer such that two signals are obtained according to the following relationships:

ST = Fourier transform of sr (t);

SQ = Fourier transform of s0 (t)

The components indicated in the previous equation Si or SQ represent the product of the reception signal s (t) mixed with the signals of the local oscillator for a phase difference of 90 °, here indicated as cos (cot) or sin (<ot) . The resulting single sideband spectrum is obtained from:

SCSB <=> Yes -j <■> SQ

In order to improve the performance of microwave motion sensors, the state of the art has proposed to provide a function based on known object detection methods, and possibly on the calculation of speed and distance, which also determines the angular positions of one or more objects. As disclosed in DE 10234 291 AI, several antennas are arranged on the receiving side for this purpose. However, this approach has the disadvantage of having to provide for each reception path a processing of the signals on the high and low frequency baseband. This, in particular for motion detectors installed on alarm systems, involves too high and inappropriate costs. Furthermore, DE 102 34 291 A1 proposes to arrange a switching between several receiving antennas, so as to make only one signal processing path necessary. EP 0987561 A2 describes a holographic switching project which provides for switching between several emitting and receiving antennas.

In Kederer, W .; Detlefsen, J .: Direction of arrival (DOA) determination based on monopulse concepts, 2000 Asia-Pacific Microwave Conference, 3-6 December 2000, pages 120-123, describes a procedure for determining the angle by means of multiple beam lobes or antenna elements in a receiving path, in which a transmitting antenna radiates the sensing field.

Advantages of the invention

The problem underlying the invention consists in providing a device for detecting an angle of incidence of an electromagnetic wave which avoids the disadvantages of the state of the art and allows an efficient and economical angle analysis.

This object is achieved, according to 1 <1> invention, cor. a detection device having the features of claim 1.

Furthermore, the object is achieved with a process indicated in claim 8.

Further embodiments of the invention can be seen from the sub-claims.

A substantial concept of the invention consists in designing an analyzer of the detection signals divided into a device for determining the possible angles of incidence of the electromagnetic wave with respect to the primary diffusion direction of the transmitter and in a device for selecting the angle of correct incidence among those possible of the electromagnetic wave with respect to the primary diffusion direction of the transmitter. In particular, in the microwave motion sensor, it is advisable to provide a separation, based on the "digital" formation of the beam, between the definitions of the angle based on its value and the differentiation between right and left.

In accordance with the process according to the invention, it is convenient to first determine two possible angle values starting from the digitized signals of the baseband in the time interval. In follow or U Z U J 3 / U D / A

at the same time, a left / right differentiation is made in the frequency range. In particular, the advantage of the method according to the invention consists in making it unnecessary to accurately determine the angle in the frequency range, since a "coarse" Fourier transformation, with few scanning values, is sufficient. The number of scan values is advantageously between just 2 and 64.

Furthermore, it is very advantageous that the method according to the invention requires little memory space and allows for short-duration calculation cycles of the angle. Such short cycles are achieved due to the short scan duration and low complexity calculations. Conveniently, therefore, the determination of the angle is in general more insensitive to disturbances, as the point of arrival can be made plausible by means of several cycles before the alarm is triggered.

The device according to the invention for detecting an angle of incidence of an electromagnetic wave substantially has:

a) a transmitter for radiating an electromagnetic wave towards a target in a primary diffusion direction;

b) at least two receiving units for receiving the electromagnetic wave returned by the target and for converting the received electromagnetic wave into at least one intermediate frequency signal;

c) a converter for converting at least one intermediate frequency signal into at least first and second detection signals; And

d) an analyzer for evaluating the first and second detection signals so as to be able to obtain the angle of incidence of the electromagnetic wave with respect to the primary diffusion direction of the transmitter, and therefore an angular position of the target with respect to the primary diffusion direction transmitter. The analyzer also has a device for determining the possible angles of incidence of the electromagnetic wave with respect to the primary diffusion direction of the transmitter by means of the first and second detection signals, and a device for selecting the angle of incidence of the electromagnetic wave corrected among those possible with respect to the primary diffusion direction of the transmitter by means of the first and second detection signals.

Furthermore, the method according to the invention for detecting an angle of incidence of an electromagnetic wave substantially has the following steps:

a) irradiation of an electromagnetic wave by a transmitter, in a primary diffusion direction, towards a target;

b) reception of the electromagnetic wave returned by the target by at least two receiving units; c) transformation of the received electromagnetic wave into at least one intermediate frequency signal by means of the at least two receiving units; d) transformation of the intermediate frequency signal into at least a first and a second detection signal by means of a converter, e

and} evaluation, by means of an analyzer, of the first and second detection signals so as to obtain the angle of incidence of the electromagnetic wave with respect to the primary diffusion direction of the transmitter, and therefore an angular position of the target with respect to the diffusion direction primary of the transmitter, including evaluation by analyzer:

el) the determination of the possible angles of incidence of the electromagnetic wave with respect to the primary diffusion direction of the transmitter, starting from the first and second detection signals, by means of an angle determination device, and

e2) choice of a correct angle of incidence among those possible of the electromagnetic wave with respect to the primary diffusion direction of the transmitter, starting from the first and second detection signals, by means of a selector.

The sub-claims present advantageous embodiments and improvements of the object of the invention.

According to a preferred embodiment of the present invention, the device for determining the angle has a beam forming device which generates sum and difference signals in the form of a beam, starting from the first and second detection signals. Preferably the beam-shaped signals are conducted to the vaile processing devices in the angle determination device.

IT2039 / 06 / B

According to a further preferred embodiment of the present invention, the beam-shaped signals are conducted both to the angle determination device 300 and to the selector 400. Conveniently, the device for forming the beam is contained in the analyzer, such as separate and identifiable form.

According to a further preferred embodiment of the present invention the transmitters for the irradiation of the electromagnetic wave in the primary diffusion direction and the at least two units for the reception of the electromagnetic wave returned by the target and for the conversion of the received electromagnetic wave into at least one intermediate frequency signal are designed for continuous wave operation. According to a further preferred embodiment of the present invention it is advantageous to design the transmitter and the at least two receiving units for pulse or modulation operation.

According to a further preferred embodiment of the present invention, the device for detecting an angle of incidence IT2039 / 06 / B

of the electromagnetic wave has at least two transmitters for the irradiation of at least two electromagnetic waves in a common primary diffusion direction, and a unit for the reception of the electromagnetic waves returned by the target and for the conversion of the electromagnetic waves received into at least one signal at intermediate frequency.

According to a further preferred embodiment of the present invention, the device for detecting an angle of incidence of the electromagnetic wave has at least two transmitters for the irradiation of at least two electromagnetic waves in a common primary diffusion direction and at least two units for the reception of the electromagnetic waves returned by the target and for the conversion of the electromagnetic waves received into at least one intermediate frequency signal.

Furthermore, it is advantageous that the determination of the possible angular positions of the target with respect to the primary diffusion direction of the transmitter on the basis of the first and second detection signals takes place by means of the angle determination device IT2039 / Q6 / B

in the time interval.

According to a further preferred embodiment of the present invention, the choice of a correct angular position of the target among those possible with respect to the primary diffusion direction of the transmitter on the basis of the first and second detection signals takes place by means of the selector in the frequency range .

To establish the primary diffusion direction it is advantageous to use a maximum value of one magnitude of the beam-shaped sum signal. Furthermore, to establish the primary scattering direction, a minimum value of one magnitude of the beam-shaped difference signal generated by the difference between the first and second detection signals can be used.

A phase shift of the beam-shaped difference signal can also be used to establish the primary diffusion direction. It is convenient for the phase shift of the beam-shaped difference signal to be 1S0 <C>. According to a further embodiment of the present invention, in the selector the angular position of the target correct between nyuj s / u o / D

those possible with respect to the primary diffusion direction of the transmitter are selected on the basis of the beam-shaped signals defined starting from the first and second detection signals.

Drawings

The drawings show the embodiments of the invention described in greater detail below.

The drawings show:

Fig. 1 a detection device for a target with a combination of microwave sensor and passive infrared sensor according to the state of the art;

Fig. 2 block diagram of a connection arrangement for an electromagnetic wave angle detection device with analog signal evaluation, to illustrate the principles of the present invention; Fig. 3 (a) the power of a reception signal as a function of a direction angle, with sum and difference signals shown on a diagram; Fig. 3 (b) the phase of a reception signal as a function of a direction angle for a sum and a difference signal according to Fig. 3 (a); 1U LM 3 / UO / D

Fig. 4 (a) a block diagram of an angle of incidence sensing device with digital beam forming and separate mixers for each receiving path, to illustrate the principles of the present invention;

Fig. 4 (b) the arrangement illustrated in Fig. 4 (a), where the separate mixers for each receiving path are replaced by a switch between the receiving antennas, to illustrate the principles of the present invention; Fig. 5 a block diagram of a device according to the invention for detecting an angle of incidence of an electromagnetic wave with digital processing and two receiving paths with I / Q mixers;

Fig. 6 an overall block diagram of the detection device according to the invention according to a preferred embodiment of the present invention; And

Fig. 7 an overall block diagram according to a further embodiment of the present invention.

In the figures, identical reference numerals identify identical components or phases

1 Ί

similar from a functional point of view.

Description of the examples of realization

Fig. 2 shows a general block diagram illustrating the operation of the present invention. In order to be able to analyze the angle of a received microwave signal, at least two antenna elements are usually used. Fig. 2, to clarify the principles of the present invention, shows an evaluation of the analog type signal. A splitter A conducts a signal from oscillator 0 to a mixer M in the two paths of the receiving signal and to a transmitting antenna 108. The signal returned by a target (not shown in Fig. 2), i.e. an electromagnetic wave, affects the receiving units 101a, 101b at a certain angle.

The receiving units 101a, 101b each have a receiving antenna 109a or 109b. The reception signals E1 or E2 are routed to a coupler preferably embodied as a 180 ° coupler. The sum signals S or difference D are mixed in the mixers M with the local oscillator signal 0 to generate corresponding intermediate frequency signals ZF, which are further iT ^ ojy / oe / B

processed in a device not shown. In the analog beam formation illustrated in Fig. 2, a number of lobes are generated by means of an antenna assembly with a beam forming element. The beam forming element is realized for example as a coupler, Rotman lens, Butler or Blass matrix and has several inputs which correspond to the lobes of the beam. The lobes of the beam are designed to have different azimuth directions and to allow an overlap of the adjacent lobes. In the overlap area of the lobes it is possible to determine the azimuth angular position of a target based on the amplitude or power ratios of the signals of adjacent lobes. Furthermore, it is also possible to evaluate the phases of the signals or carry out a combined analysis of amplitudes (or powers) and phases.

In addition, for example, the signals can be represented, with their relative values and phases, in the form of complex numbers (phasors) and lead to a complex functional adaptation of the relationship between the azimuth angle and the quotient of the complex reception signal.

In principle, using procedure IT2039 / 06 / B

single pulse, it is possible to carry out a particularly simple determination of the angle. In this case, two antenna elements are used approximately half wavelength apart in free space, through which two beam lobes are created by measuring and summing the signals of the antenna elements in phase (sum lobes) or in counterphase (difference lobes). Such sum or difference signals, which derive from the sum or difference lobes, can be generated with the help of the K coupler. It is also possible to switch between the output signals of the coupler to save a mixer path and baseband. . However, what has just been illustrated has the disadvantage that the coupler and any switch would cause further losses in the receiving path, which would reduce its sensitivity and range.

It should be noted that in a development of a high frequency front end of a microwave device for the detection of an angle of incidence of an electromagnetic wave, more than two antenna elements can also be used with frequency transposition and evaluation. reception signals for detecting the azimuth angular position of a target. The phase difference Δφ between the signals of the antenna elements that occurs due to the incidence delay of the electromagnetic wave as a function of the azimuth angle Θ is used in any case for the evaluation of the angle.

Figs. 3 (a) and 3 (b) show a strength of the receive signal 114 or a phase of the receive signal 115 as a function of a direction angle (azimuth angle) 113. The sum signal 305a in turn derives from the lobes of the sum beam, while the difference signal 305b derives from the lobes of the difference beam. In the example of embodiment illustrated in Fig. 3, the characteristic curve of the beam of two "patch" elements half wavelength apart in free space was obtained from an analytical model, hitting the elements with identical amplitude and phase (lobes of the beam sum) and with the same amplitude, but in counterphase (difference beam lobes). In the phase trend of the difference lobe, with passage to zero power, a phase shift of 180 ° occurs (with an angle of 0 ° (azimuth angle equal to zero)).

The angle at which the target returns the electromagnetic wave radiated by the emitting antenna 108 (see Fig. 2) in the direction of the receiving antenna 109a, 109b (see Fig. 2) is obtained from the relationship between the signals of the beam lobes of sum and difference, observing the phase of the difference lobe with respect to that of the sum lobe. In the formation of the so-called "digital" beam, the signals, and in this case especially the phase differences, of the individual elements or groups of antenna elements are processed and analyzed separately, as shown in Fig. 5. Contrary to the arrangement of Fig. 2, in this case the mixing procedures in the receiving units 101a or 101b are completely distinct from each other, so that the intermediate frequency signals can be obtained separately. The device illustrated in Fig. 5 for detecting an angle of incidence of an electromagnetic wave consists of a transmitter 1C2 and two receiving units 10a, 101b. The transmitter has a transmitting antenna 108 on which a transmission signal 106 is transmitted. The transmission signal 106 is received by an oscillator 103, the oscillator signal being conducted by means of a divider 110 to the transmitting antenna 108 and to the two units receivers 101a, 101b.

It should be noted that, although not illustrated in the figures, more than two receiving units can be used for the reception of the electromagnetic wave and for the analysis of an angle of incidence of the electromagnetic wave. Furthermore, it is possible that the device for detecting an angle of incidence of the electromagnetic wave has at least two transmitters 102 for the irradiation of at least two electromagnetic waves in a common primary diffusion direction, being in this case only a receiving unit 101a arranged upon reception of the electromagnetic wave returned by the target and for the conversion of the received electromagnetic wave into at least one intermediate frequency signal. The transmitters are alternatively connected to the oscillator signal splitter, for example by means of a switch.

Furthermore, it is possible that the device for detecting an angle of incidence of the electromagnetic wave has a combination of 11ZUJ3 / UO / ϋ

at least two transmitters 102 for the irradiation of at least two electromagnetic waves in a common primary diffusion direction and at least two units for the reception of the electromagnetic waves returned by the target and for the conversion of the electromagnetic waves received into at least one intermediate frequency signal.

Fig. 4 (a) shows a device according to the invention provided with a transmitter 102 and two receiving units 101a, 101b. A signal from the oscillator 104 is conducted to the divider 110 and thus acts as a transmission signal 106, conducted to the transmitting antenna 108, and as a signal from the local oscillator, conducted to the mixers 11a, 11b. The signals picked up by the receiving antennas 11a, 109b are conducted to the mixers 11a or 11b in the form of reception signals 107a or 107b. An intermediate frequency signal 112a, 112b emitted by the mixers after mixing is then conducted to a converter described below with reference to Figs. 6 and 7.

Fig. 43⁄4ο) shows a detection device which corresponds in its substantial components to that of Fig. 4 (a), except that the two mixers llla, lllb are replaced by a single mixer 111 which emits a single signal at intermediate frequency 112. In order to further process the reception signals 107a, 107b of the two receiving units 10a, 101b, picked up by the two receiving antennas 109a, 109b, a switch U is set up which alternately activates the signals of one of the two receiving units 101a , 101b on the mixer.

Fig. 5 shows in greater detail the arrangement represented in Fig. 4 (a), since mixers I / Q llla, lllb or lllc, llld are shown in the arrangement of Fig. 5. To divert the I / Q signals, in order to generate an I signal, the signal of the oscillator 104 is mixed directly with the receive signal 107a, 107b in a mixer lllb or llld, while a signal Q SQ is obtained by mixing the signal of the oscillator 104, which has a phase shift generated in a delay unit 105a or 105b, with the reception signal 107a, 107b. Certain output signals of the first and second receiving unit 10a or 10lb are then available for analysis in a converter 200 (described below with reference to Figs. 6 and 7) the output signals Su, SQio Si2, SQ2-Di the following explains how the transceiver device 100 illustrated in Fig. 5 interact with the other modules of the device according to the invention for detecting an angle of incidence of an electromagnetic wave, that is a converter 200, a device for determining the angle 300, an analyzer 500 and a beam forming device 600 (see Figs. 6 and 7 below).

The advantage of the so-called "digital" beam formation consists in requiring a less bulky construction form. Furthermore, the digital beam formation, in the analysis phase, proves to be substantially more flexible and powerful, in particular in principle, by employing an appropriately increased number of antenna elements or receiving devices, there are possibilities for a multi-objective resolution, or more lenses in a range of celi with high resolution procedure. The distinguishability of targets in multi-objective configurations, in an exclusively analog beam formation, is 1 limited to the width of the lobes, i.e. in principle, 1 1V U J 3 / U D / Ì3

with the formation of the analog beam, within the angle it is impossible to distinguish the adjacent objectives, whose distance is less than the width of a beam lobe, with consequent disadvantages.

To avoid ambiguity, the distance between the antenna elements must be within half the wavelength in free space (comparable to the greater curvature in antenna assemblies or light grids).

When a phase analysis of the receive signals is used to determine the angle, which is particularly the case with digital beam formation, an I / Q mixer must be used to obtain a phase reference of the mixed signal with respect to the 1> local oscillator and then correctly determine the sign of a detected Doppler frequency. With the single sideband spectrum described above, a phase difference is obtained between two lines at doppler frequency according to the following relationship (1):

for lines S (Af) and '* (1)

feel a phase factor. The phase φ

of the parts that depend on the distance and the azimuth angular position. From a phase difference of the signals of two adjacent receiving antennas according to the relation (1) just indicated, it is possible to determine the angular position Θ based on the relation:

A \ φ

Θ = arcsin (2) a 2 ic

where at distance of the phase centers of the two receiving antennas.

If switching between the individual receiving antennas 109a, 109b, ... is used, the switching between the antenna elements must occur at such a speed that the phase portion in the distance varies only negligibly.

It is emphasized that the oscillator 103 illustrated in Fig. 5 (high frequency oscillator) in the simplest case is made as a continuous wave source (CW, Continuous Wave). Additionally, the high frequency oscillator 103 can be pulsed to reduce power consumption. Furthermore, it is possible to use the principle according to the invention on modulated detection systems (particularly pulsed or pulsed and doppler radar, or FSK modulated).

With reference to Fig. 5 and 6 the r: 7UJy / Ub / a is now described

detection principle of the device according to the invention. A signal 104 generated by the oscillator 103 is divided into a transmission signal and a signal of the local oscillator 106 or 104. The reception signals are mixed with the signal of the local oscillator 104 in I / Q llla-llld mixers.

The I / Q mixers can be made, for example, in such a way as to present a phase delay of 90 ° in the conduction of the signal of the local oscillator 104, or with delay units 105a, 105b. Furthermore, it is possible to provide for the use of a 90 ° hybrid device. The phase delay also, although Fig. 5 does not show it, can also be inserted in the receiving path (in Fig. 5 above the mixers llla-llld). The mixers 11a-11d themselves, in a preferred embodiment of the present invention, are made as push-pull mixers using for example 90 ° or 180 ° couplers. A particularly advantageous embodiment is represented by the monodiode mixer, which allows an economic saving compared to the mixers described above. When a moving target is within the detection range of the J.iZUJ? / UO / D

transceiver device, signal components with one or more doppler frequencies are present on the mixer outputs. The signal parts in the frequency range of the signal 104 generated by the oscillator 103, the higher mixed products and the resulting harmonics in the llla-llld mixers are suppressed by suitable high frequency decoupling and filtering on the mixer outputs (see below, Fig . 6).

The obtained baseband signals Su, SQi, Su, SQ;? Are filtered in the filtering units 202a-202d, realized as low-pass filters, after the corresponding signals have been amplified in amplifiers (optional) 201a-201d ( Fig. 6).

Finally, in the conversion units 203a-203d (A / D), with a scanning speed 204 the transformation of the analog signal into digital signals takes place, brought to the single conversion units 203a-203d. The signal paths S.ii and S52 have an adaptation unit 205a or 2G5b. Finally, or after a multiplication by (--i) in the adaptation units 205a, 205b, the signals emitted by the conversion units 203aIT2039 / 06 / B

203d are combined or added into the individual combination units 206a, 206b. In this regard, the signals corresponding to S: 1 and <S> Q1 are combined in unit 206a, while those corresponding to SI2 and Sc2 are combined in unit 2Q6b.

The combination units 206a or 206b, following the combining process, provide first or second detection signals 207a or 207b which will be further processed.

The first and second sense signals 207a, 207b are conducted to an analyzer 500.

With the low-pass filtering of the baseband signals, the presence of artifacts, or aliasing, is avoided. Furthermore, any signal frequencies typical of disturbances are suppressed. The scanning speed 204 is set as a constant time interval At and is determined by the highest Doppler frequency and the characteristic curve of the baseband filter (anti-aliasing filter). The scanning speed At is usually between 1 and 2.5 milliseconds {ms}, which corresponds to a scanning frequency between 400 and 1000 Hz. From this derives the resolution of the spectrum:

ni

11ZUU3 / UO / D

Δί = 1 / (Ν - At) (2a)

The duration of a scan derives from the required frequency resolution, showing the following table the typical resolutions in the range between 1 and 3 Hz:

IT2039 / 06 / B

In order to cover a range of standard distances between 0.5 and 25 m, the data must include a dynamic field with an amplitude equal to (25 / 0.5) <:> ≡ 2500. The scanned and digitized I and Q signals express signals of complex time / UU / LD

on the relative scanning moments Ti according to the following equation (3):

3⁄4 (ti) "Su (ti) <=> j-SQJ (t,)

The sign of the quadrature component is obtained from the phase of the signals I and Q. It changes for example when Q is defined in advance before I. Complex time signals of this type contain all the phase-frequency information, therefore in particular those on the positive sign or negative of the doppler frequency, i.e. on the direction of movement of the target with respect to the sensor.

Both the signals (at least two) coming from the at least two receiving units 10a-10lb, that is the first detection signal 207a and the second detection signal 207b, in a first embodiment of the present invention are led directly to a selector 400 which is located in the analyzer 500. The selector is described in detail below.

The first and second sense signals 2C7a, 207ò are also routed to a device for 1U UJ ^ / UU / D

the determination of the angle 300 disposed in the analyzer 500. In the first example of preferred embodiment of the present invention the device for determining the angle 300 has a device for forming the beam 600 which allows to generate sum and difference signals 305a or 305b starting from the first and second detection signals 207a, 207b, illustrated with reference to Fig. 3. Said sum and difference signals 305a, 3G5b allow the detection of a single angle of incidence of an electromagnetic wave. With complex digitized time signals, beam formation advantageously takes place digitally, in the time interval. A particularly simple implementation is obtained by providing two receiving units 101a, 101b, so as to be able to generate the sum and the difference of the two derived signals with reference to equation i3).

It should be noted in this regard that, although the present description does not deal with the subject in detail, more than two receiving units 10a, IGlb can be provided, so as to be able to process more than two detection signals 207a, 2C / b in the analyzer 500 The sum and difference signals obtained with the previous equation 305a or 305b are calculated as indicated by the following equation (4):

From the complex time signals of the beam lobes obtained with equation (4) we proceed at this point to the generation of a value or the detection of a peak value, or another form of rectification, also generating an average time value . An efficient way to get the average value is to run the moving average by applying equation (5) below.

An average calculation performed with equation (5) requires extremely small memory capacity.

From the average values ma ,,:. Ie mDiFF, it is now possible to calculate two angular values. The calculation of the value and of the average according to equation (5) is carried out in the angle determination device 300 of the analyzer 500 by means of the value calculation unit 302a, 302b and the average calculation unit 303a, 303b, respectively. The sum signal 305a and the difference signal 305b obtained are then transmitted to a computing unit 304 from which the angle Θ is directly obtained, which corresponds to an angle of incidence of the electromagnetic wave returned by the target (azimuth angle).

To calculate the azimuth angle, the ratio m3UM / mDIFF is now generated and an interpolation of the measured characteristic curves is performed, that is the angular trend with respect to the ratio msra / mDiFF. Alternatively, it is also possible to insert the ratios mS [jM / mDIFF with the relative angular values in a table, interpolating the intermediate values. This allows to calculate the value of the azimuth angle, but not to determine its side (cf. Flg. 3 (a)), ie it is not possible to determine if the angle is to the right or to the left with respect to 0 °.

Antenna structure, manufacturing tolerances, phase and amplitude differences between signal paths, and so on, can result in asymmetry in the mSUM / mDIFF ratio as a function of the azimuth angle of the target. In this case the device for determining the angle 300, for a ratio mSuM / mDiFF, provides two possible azimuth angles with different values, to the right and to the left of a primary diffusion direction. The primary diffusion direction does not necessarily coincide with 0 °, however it is known for example thanks to calibration measurements.

The angle determination device 300 does not allow "left" and "right" to be identified. For this type of distinction the analyzer 500 also has a selector 400 which works in the frequency range.

The advantage of the moving time average calculated in the device for determining the angle 300, on the other hand, is constituted by lesser requirements in terms of memory and by the flexibility of adjusting the moment of calculation of the average. For example, the chosen averaging time may be greater than the standard scan intervals for a transformation of

39

Fourier, illustrated below with reference to the description of the selector 400. In this way the average can be calculated without taking into account short-term disturbances and faster effects, and the azimuth angle can be determined in a manner substantially insensitive to disturbances. Furthermore, the output signal of the moving average (Θ) should be continuously available, unlike for example the data obtained with the Fourier transform, which are always available at the end of a scanning interval.

What has been illustrated allows greater flexibility in processing the signals and the azimuth angles derived from them. A Fourier transformation performed by means of movable and superimposed scan windows has the clear disadvantage of increasing the memory requirement and processing time. When more than two beam lobes or more than two receiving units 101a, 101b are used, the lobe with the highest signal value must first be determined, thus detecting the adjacent lobe with the immediately lower average value. Between the two, in a similar way, yes

determines the angle. Also in this case ambiguities occur, i.e. there may be two angular values whose signal amplitudes in the two lobes are identical. The identification of the correct angle, similar to a right-left distinction in the sum / difference lobes, occurs on the basis of the phase difference, as described below. The selector 400, contained in the analyzer 500, presents for each signal point, i.e. the path for a signal coming from the receiving unit 101a and the path for a signal coming from the receiving unit 101b, i.e. the first and the second detection signal 207a or 207b, consecutively connected window units 401a or 401b and transformation unit 402a or 402b. As illustrated below, a differentiation unit 403 to which the signals emitted by the transformation units 402a or 4Q2b, transformed in the frequency range are conducted, then makes a right-left distinction R / L.

Real objects generate not only a thin doppler frequency line, but a broad spectrum of doppler frequency components (e.g. iTZUjy / υβ / Β

caused by running people moving their torso, arms and legs at different speeds). These different speeds are found in the single sideband Doppler spectrum. Significant frequency lines are identified, for example, with a search for maximum values above a certain threshold. The angle is determined for all frequency lines on the basis of the relations mentioned (2). When several objects with different velocities assume different angular positions it is possible to determine the angle for all the frequency components of the Doppler spectrum. Furthermore, it must be ensured that a line (in a frequency "Bin") of the doppler spectra of the baseband signals contains only the effects of the movement of an object, in order not to falsify the determination of the angle. through the phase difference according to the relation (2) indicated above it is sensitive to disturbances.For example, a running person can simultaneously generate positive and negative doppler frequencies, moving the body towards the miereonde sensor while an arm swings backwards. Therefore the resolution Δ £ of the transformation of ITZUjy / Ub / B

Fourier must be good enough.

The present invention solves this problem thanks to the division of the analyzer in an angle determination device 300 (described above) and in a selector 400, which must provide only a right-left distinction. In this way substantial advantages are obtained in that the selector 400 and therefore the analyzer 500 can be simplified overall.

The transformations from time interval to frequency interval to be performed in the transformation units 402a or 402b, Fourier transformations in the preferred embodiment example, can therefore be structured in a very simple way, so as to be able to perform the arithmetic functions of the transformation of Fourìer on low cost microcontrollers. This leads to simplifying and making the entire analyzer of the detection device according to the invention more economical. By means of the windowing units 401a or 401b upstream of the transformation units 4Ù2a or 402b it is thus possible to generate a section of the complex digitized time signal relatively short. In the simplest case, a rectangular window is used, i.e. only a time section of the signal is selected. In addition, other window functions can be used advantageously to suppress secondary maximum values in the spectrum (in the doppler frequency spectrum), e.g. windows of Hamming, Hanning, Kaiser, Tschebyscheff, etc.

The sections thus generated are finally subjected to a Fourier transformation in the transformation units 402a, 402b. The time section prepared by the upstream windowing units 401a, 401b is therefore so short that for example it is possible to process two complex time signals in a low-cost microcontroller. Classical orders of magnitude are for example equal to N = from 2 to 64 scan values. A resolution of all the doppler components in this way is impossible, because the frequency resolution Δί (see equation (2a)) is so coarse that within a frequency line of amplitude Δί there are in general doppler components of several parts. of the target. Advantageously, with the method according to the invention a detailed resolution of the doppler components in the spectrum IT ^ UJy / Ub / B

frequency is in any case superfluous, since the determination of the angle can be carried out in a separate device 300.

A representative frequency line for the target is determined in the output signals of the first and second receiving units 101a, 101b. For this purpose, you can choose, for example, the line with the greatest amplitude, or, for example, you can always choose the same representative frequency line for moving objects.

The right-left distinction is made on the basis of the phase difference between this frequency line in the signal spectra of the antenna elements. For this purpose it is necessary to determine only the sign of the phase difference, since this sign can be established in a sufficiently reliable way even with a resolution of a coarse frequency Δί (previous relation (2a)).

In the presence of more than two beam lobes, a distinction can be made between primary and secondary lobes on the basis of the phase difference. Furthermore, it is possible, again on the basis of the phase difference, to make a relatively imprecise estimate of the angle, for example IT2039 / 06 / B

according to equation (2). This can be used for a consistency check as regards the correspondence of the signals emitted by the device for determining the angle 300 and by the selector 400.

Fig. 7 describes a further example of embodiment according to the present invention. The components identical to those of Fig. 6 are marked with the same reference numbers and will not be illustrated in greater detail, in order to avoid descriptive redundancies. Contrary to the connection arrangement of Fig. 6, the device for forming the beam 600 is not part of the device for determining the angle 300, but is connected upstream of the device for determining the angle 300 and of the selector 400, as single separate and identifiable unit. Consequently, beam-shaped signals, i.e. the sum and difference signals 305a or 305b, are conducted to the selector. Therefore, there is the advantage that even in the presence of a reduced angular field, around: a value of 0 <a>, a phase difference of 180 ° is generated between positive and negative angles. This phase difference can be detected in 114UJ ^ / UU / O mode

extremely precise and reliable, as previously illustrated with reference to Fig. 3 (b).

In the arrangements shown in Figs. 6 and 7 the determination of the angle takes place in the time interval in a separate device 300, while the right-left distinction makes use of a separate selector 400 in the frequency interval.

As regards the traditional device, represented in Fig. 1, for detecting an angle of incidence of an electromagnetic wave, please refer to the introductory description.

Claims (3)

IT2039 / 06 / B Claims 1. Device for detecting an angle of incidence of an electromagnetic wave, golden of: a) a transmitter (102) for radiating an electromagnetic wave towards a target, according to a primary diffusion direction; b) at least two receiving units (101a, 101b) to receive the electromagnetic wave returned by the target and convert it into at least one intermediate frequency signal (112a, 112b); c) a converter (200) for transforming at least one intermediate frequency signal (112a, 112b) into at least first and second detection signals (207a, 207b); And d) an analyzer (500) to evaluate the first and second detection signals (207a, 207b), so as to obtain the angle of incidence of the electromagnetic wave with respect to the primary diffusion direction of the transmitter (102) and, therefore , an angular position of the target relative to the primary spread direction of the transmitter (102), characterized by the fact that the i500j analyzer has: c) ur. device for determining the possible angles of incidence (300) of the electromagnetic wave with respect to the primary diffusion direction of the transmitter (102) by means of the first and second detection signals (207a, 207b); And f) a selector (400) of the correct angle of incidence of the electromagnetic wave, among those possible, with respect to the primary diffusion direction of the transmitter (102) by means of the first and second detection signals (207a, 207b). 2. Device according to claim 1, characterized by the fact that the angle determination device (300) has a beam forming device (600) which generates sum (305a) and difference (305b) signals in beam form, starting from the first and second detection signals ( 207a, 207b). 3. Device according to claim 1, characterized by the fact that the analyzer (500) is provided with a beam forming device (600) which generates sum (305a) and difference (305b) signals in beam form, starting from the first and second detection signals (207a, 207b) ), such that 1 sudoerti 43 iTituy / ub / B signals in beam form (305a, 305b} can be conducted both to the angle determination device (300) and to the selector (400). 4. Device according to claim 1, characterized by the fact that the transmitter (102) for the irradiation of the electromagnetic wave in the primary diffusion direction and the at least two receiving units (101a, 101b) which receive the electromagnetic wave returned by the target and convert it into at least one intermediate frequency signal (112a , 112b) are designed for continuous wave (CW) operation. 5. Device according to claim 1, characterized by the fact that the transmitter (102) for the irradiation of the electromagnetic wave in the primary diffusion direction and the at least two receiving units (101a, 101b) which receive the electromagnetic wave returned by the target and _a convert into at least one intermediate frequency signal (112a , 112b) are designed for pulse or modulation operation. 6. Device according to claim 1, nvuj <y> / ub / ΰ characterized by the fact that the detector for determining an angle of incidence of the electromagnetic wave has a) at least two transmitters (102) for the irradiation of at least two electromagnetic waves in a common primary diffusion direction; And b) a receiving unit (101a) which receives the electromagnetic wave returned by the target and converts it into at least one intermediate frequency signal (112a, 112b). 7. Device according to claim 1, characterized in that the detector for determining an angle of incidence of the electromagnetic wave has at least two transmitters (102) for the irradiation of at least two electromagnetic waves in a common primary diffusion direction and at least two receiving units (101a, 101b) which receive the electromagnetic waves returned by the target and convert them into at least one intermediate frequency signal (112a, 112b). 3. Procedure for determining an angle of incidence of an electromagnetic wave, which consists of the following steps: IT2Ui9 / Ub / B a) irradiation, by means of a transmitter (102), of an electromagnetic wave towards a target, according to a primary diffusion direction; b) reception, by means of two receiving units {101a, 101b), of the electromagnetic wave returned by the target; c) conversion, by means of at least two receiving units (101a, 101b), of the received electromagnetic wave into at least one intermediate frequency signal (112a, 112b); d) transformation, by means of a converter (200), of at least one intermediate frequency signal (112a, 112b) into at least a first and a second detection signal (207a, 207b); And e) evaluation, by means of an analyzer (500), of the first and second detection signals (207a, 207b), so as to obtain the angle of incidence of the electromagnetic wave with respect to the primary diffusion direction of the transmitter (102); and , therefore, an angular position of the target with respect to the primary diffusion direction of the transmitter (102), characterized in that the evaluation step e) has the following steps; el) definition of the possible angles of incidence IT2039 / 06 / B of the electromagnetic wave with respect to the primary diffusion direction of the transmitter (102), starting from the first and second detection signals (207a, 207b), by means of a device for determination of the angle (300); And e2) selection of a correct angle of incidence of the electromagnetic wave among those possible with respect to the primary diffusion direction of the transmitter (102), starting from the first and second detection signals (207a, 207b), by means of a selector (400) . 9. Process according to claim 8, characterized by the following further steps: a) formation of sum (305a) and difference (305b) signals, starting from the first and second detection signals (207a, 207b), to obtain signals in beam shape by a beam forming device (600) provided in the analyzer (500); And b) conduction of the signals in the form of a beam (305a, 305b) both to the angle determination device (300) and to the selector (400). 10. Process according to claim 3, characterized in that a definition of the possible angular positions XT2039 / 06 / B to the direction of the target with respect of the transmitter (102), primary diffusion starting from the first and second detection signals (207a, 203⁄4>, by means of a device for determining the angle <(> 300 <)>, in the time interval. Method according to claim 8, characterized by the fact that the choice of an angular position of the target correct, among those possible, with respect to <i> a primary diffusion direction of the transmitter (102), starting from the first and second signals detection (207a, 207b), by means of a selector (400), is performed in the frequency range. 12. Process according to claim 9, characterized in that to determine the direction of diffusion primary, a maximum value of one is used magnitude of the beam-shaped sum signal (305a). 13. Process according to claim 9, characterized in that to determine the primary diffusion direction, a minimum value of a magnitude of the difference signal (3G5b; a n rrra :> 3 I T Z U J S / U b / t5 of beam. 14. Process according to claim 9, characterized in that A phase shift of the beam-shaped difference signal (305b) is used to determine the primary scattering direction. 15. Process according to claim 14, characterized in that the phase shift of the beam-shaped difference signal (305b), for determining the primary diffusion direction, is 130 degrees. 16. Process according to claim 9, characterized in that in the selector (400) the correct angular position of the target, among those possible, with respect to the primary diffusion direction of the transmitter (102) is selected on the basis of the beam-shaped signals (305a, 305b}. 17. Process according to claim 10, characterized in that a definition of the possible angular positions of the targets with respect to the primary diffusion direction of the transmitter detection (207a, 207b), by means of the device for the determination of the angle (300) comprises a straightening or a detection of a value of peak. 18. Method according to claim 17, characterized by the fact that a definition of the possible angular positions of the target with respect to the direction of primary diffusion of the transmitter (102), a starting from the first and second signal of detection (207a, 207b), by means of the device for determining the angle (300), includes a moving average that adds up a value medium, detected in one detection cycle previous, and one or more signal values detected subsequently with the use of factors of individual weighting. The Agent (Paolo Jaumann)