Radiant-panel radio stimulation device

Abstract

A stimulation device notably for testing radio reception devices is provided. It includes a signal generator delivering an amplitude-phase law for beam-forming purposes, transmitted in the form of a composite laser beam which illuminates a matrix of photodiodes of an emission subassembly with active modules separate from the generator, each wavelength of the beam carrying one of the signals defining the amplitude-phase law, intended for an active module. The device comprises means for measuring the orientation of the composite laser beam relative to the matrix of photodiodes of the emission subassembly and the distance traveled by the beam thereto, and correcting the phase law generated by the signal generator so as to neutralize the stray phase-shifts induced by these parameters on the signals transmitted to the emission subassembly.

Claims

1. A radiant panel radio stimulation device, for emitting a test signal to a reception antenna, said radiant panel radio stimulation device comprising a subassembly generating excitation electrical signals each having a phase corresponding to a desired phase law {Δφ.sub.n} and at least one emission subassembly configured to amplify and radiate said excitation electrical signals so as to emit a radio beam in a direction determined by said desired phase law {Δφ.sub.n}, the excitation electrical signals being transmitted by the subassembly generating excitation electrical signals to the at least one emission subassembly in the form of laser waves modulated by said excitation electrical signals and forming a composite laser beam directed toward a surface of a set of photodetectors incorporated in the at least one emission subassembly, wherein the subassembly generating excitation electrical signals and the at least one emission subassembly are arranged facing one another so that the composite laser beam is directed toward the surface of the set of photodetectors with an incidence (α, β) relative to a reference axis and travels a distance D between its point of emission M and a reference point O situated on the reference axis at the surface of the set of photodetectors, and wherein the radiant panel radio stimulation device comprises a correction system configured to measure the values α, β and D and deliver a corrected phase law {Δφ.sub.n′} that is substituted for the desired phase law {Δφ.sub.n}, the corrected phase law being defined in such a way that the radio beam produced from the excitation electrical signals generated by the subassembly generating excitation electrical signals is oriented in the direction determined by said desired phase law {Δφ.sub.n}.

2. The radiant panel radio stimulation device as claimed in claim 1, wherein the corrected phase law {Δφ.sub.n′} is determined from a calculation of a path-length difference δ.sub.n=D.sub.n′−D generated, at each of the photodetectors of the set of photodetectors, by an angle of incidence of the composite laser beam on the surface of the set of photodetectors of the at least one emission subassembly (42), Δφ.sub.n′ being defined by the relationship: ${\mathrm{\Delta \phi }}_n^{\prime }={\mathrm{\Delta \phi }}_n-2\pi \frac{f_s}{c}.Math.{\delta }_n;$ D.sub.n′ representing the distance between the point of emission M of the composite laser beam and a position P.sub.n of the photodetector considered, and f.sub.s is the frequency of the radio beam.

3. The radiant panel radio stimulation device as claimed in claim 2, wherein the set of photodetectors is formed of photodetectors and the photodetectors which form the set of photodetectors of the at least one emission subassembly are arranged in a plane (xOz) on which their positions P.sub.n are registered, in terms of polar coordinates, by a distance d.sub.n′ and an angle γ.sub.n′, the path-length difference δ.sub.n is defined, for each photodetector, by the following relationship: $\begin{array}{c}{\delta }_n=D_n^{\prime }-D\\ =D.Math.\left(\sqrt{1-2\left(\cos {\gamma }_n^{\prime }\cos \mathrm{\beta cos\alpha }+\sin {\gamma }_n^{\prime }\sin \beta \right)\left(\frac{d_n^{\prime }}{D}\right)+{\left(\frac{d_n^{\prime }}{D}\right)}^2}-1\right).\end{array}$

4. The radiant panel radio stimulation device as claimed in claim 3, wherein the values α, β and D are determined by considering a plurality of non-aligned points C.sub.n, situated on the surface of the set of photodetectors, and by determining a distance D.sub.n separating the point emission M of the composite laser beam from each of the points C.sub.n considered.

5. The radiant panel radio stimulation device as claimed in claim 4, wherein at least three non-aligned points are considered.

6. The radiant panel radio stimulation device as claimed in claim 5, wherein the points C.sub.n are registered in the plane (xOz) by their distance d.sub.n to the reference point O and by an angle γ.sub.n between an axis linking the point C.sub.n considered to the point O and the reference axis, D, α and β are given by the following relationships: $D=\frac{\sqrt{\frac{d_2{d}_3\left(D_1^2-d_1^2\right)\left[\cos {\gamma }_2\sin \left({\gamma }_1-{\gamma }_3\right)-\cos {\gamma }_3\sin \left({\gamma }_1-{\gamma }_2\right)\right]}{d_3\left(d_2\cos {\gamma }_2-d_1\cos {\gamma }_1\right)\sin \left({\gamma }_1-{\gamma }_3\right)-d_2\left(d_3\cos {\gamma }_3-d_1\cos {\gamma }_1\right)\sin \left({\gamma }_1-{\gamma }_2\right)}+}}{\frac{d_1\cos {\gamma }_1\left[d_2\left(D_3^2-d_3^2\right)\sin \left({\gamma }_1-{\gamma }_2\right)-d_3\left(D_2^2-d_2^2\right)\sin \left({\gamma }_1-{\gamma }_3\right)\right]}{d_3\left(d_2\cos {\gamma }_2-d_1\cos {\gamma }_1\right)\sin \left({\gamma }_1-{\gamma }_3\right)-d_2\left(d_3\cos {\gamma }_3-d_1\cos {\gamma }_1\right)\sin \left({\gamma }_1-{\gamma }_2\right)};}$ $\beta =\mathrm{Arcsin}\frac{\left(d_1^2+D^2-D_1^2\right)d_2\cos {\gamma }_2-\left(d_2^2+D^2-D_2^2\right)d_1\cos {\gamma }_1}{2d_1{d}_{2}D\sin \left({\gamma }_1-{\gamma }_2\right)}\mathrm{and}$ $\alpha =\mathrm{Arc}\cos \frac{\frac{d_1^2+D^2-D_1^2}{2d_{1}D}-\sin {\gamma }_1\sin \beta }{\cos {\gamma }_1\cos \beta }.$

7. The radiant panel radio stimulation device as claimed in claim 4, wherein the distance D.sub.n is measured by laser rangefinding.

8. The radiant panel radio stimulation device as claimed in claim 4, wherein the distance D.sub.n is measured by using the composite laser beam produced by the subassembly generating excitation electrical signals.

9. The radiant panel radio stimulation device as claimed in claim 1, wherein the set of photodetectors consists of a matrix of photodiodes each associated with an optical filter configured to allow the exposure of a photodiode considered of the matrix of photodiodes only to one of the laser waves modulated by said excitation electrical signals and forming the composite laser beam.

10. The radiant panel radio stimulation device as claimed in claim 1, further comprising an electrical signal generator subassembly and at least two emission subassemblies, an aimed optic being configured to direct the composite laser beam alternately to one or more of the emission subassemblies, the correction system being configured to deliver, at each moment, the corrected phase law {Δφ.sub.n′} corresponding to the emission subassembly to which the composite laser beam is directed at the moment considered.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The features and advantages of the invention will be better appreciated from the following description, a description which is based on the attached figures which present:

(2) FIG. 1, a schematic illustration of the structure of a first type of radiant panel radio stimulation device known from the prior art;

(3) FIG. 2, a schematic illustration of the structure of a second type of radiant panel radio stimulation device known from the prior art;

(4) FIG. 3, a schematic illustration of the structure of a third type of radiant panel radio stimulation device known from the prior art;

(5) FIG. 4, a schematic illustration of the structure of an exemplary embodiment of the radiant panel radio stimulation device according to the invention;

(6) FIGS. 5 to 7, illustrations that highlight the technical problem posed in the context of the invention and the nature of the solution provided by the invention;

(7) FIG. 8, a schematic illustration of the structure of a particular embodiment of the device according to the invention.

(8) It should be noted that, for the attached figures, a functional or structural element that is the same preferably bears one and the same reference symbol.

DETAILED DESCRIPTION

(9) FIG. 4 schematically presents, by way of nonlimiting example, the structure of a radiant panel radio stimulation device implementing the invention.

(10) Such a device comprises two physically separate subassemblies:

(11) a first subassembly 41 comprising an electrical signal generator 411 producing electrical signals 412 phase-shifted relative to one another in accordance with a given phase law, the phase law applied corresponding to the direction in which it is wanted to orient the emission of the test radio signal;

(12) a second emission subassembly 42 comprising beam-forming radiant panels, consisting of a certain number of emission modules 421 configured to each radiate one of the electrical signals generated.

(13) The subassembly 41 further comprises means 413, 414 and 415 that make it possible to perform the transmission of the electrical signals 412, on an optical carrier 43 modulated by said signals, to the subassembly 42.

(14) The subassembly 42 comprises, for its part, a set of means 422 for handling the reception of the composite laser beam 43 and the demodulation thereof, so as to restore the electrical signals carried by the light wave.

(15) The first subassembly 41 thus primarily comprises, conventionally:

(16) a electrical signal generator 411 producing N electrical signals 412: s.sub.0(t)=S.sub.0 cos(ωt+Δφ.sub.0), s.sub.1(t)=S.sub.1 cos(ωt+Δφ.sub.1), . . . , s.sub.N-1(t)=S.sub.N-1 cos(ωt+Δφ.sub.N-1), the structure of said signal generator being able to be analogous, for example, to one or other of those illustrated by FIG. 1 or 2;

(17) N laser sources of distinct wavelengths λ.sub.0, λ.sub.1, . . . , λ.sub.N-1;

(18) N optical modulators 413, each optical modulator allowing the amplitude modulation of a laser source of wavelength λ.sub.n by an input electrical signal S.sub.n cos(ωt+Δφ.sub.n); a multiplexer 415 making it possible to sum the N modulated laser signals 414 produced, carrying the amplitude-phase law, and form a composite laser signal 416;

(19) an aimed optic 417, for correctly radiating the composite laser signal 416, that is to say forming a composite laser beam 43, directing it and focusing it correctly to completely illuminate the light wave reception means 422 of the emission subassembly 42. In the example of FIG. 4, the means 422 consist of a planar matrix of photodiodes 423;

(20) electrical energy supply and utility circuits, not represented in FIG. 4.

(21) According to the invention, the first subassembly 41 further comprises a system for correcting the phase law applied to the signal generator 411, the system itself comprising:

(22) a measurement module 44 making it possible to determine the quantities D, α and β. D represents the distance between the aimed optic 417 and the matrix of photodiodes 422, and (α,β) represents the angular orientation of the axis of the composite laser beam 43 to a reference direction defined by the matrix of photodiodes 422;

(23) a correction module 45 whose role is to calculate a corrected amplitude-phase control law, intended to be applied to the signal generator 411, a law which is a function of the measurements of the quantities D, α and β performed by the measurement module 44.

(24) The principle of operation of this correction device is presented hereinbelow in the text.

(25) The emission subassembly 42, for its part, comprises:

(26) a matrix 422 of N photodiodes 423, each photodiode being equipped with an optical filter 424 centered on a wavelength λ.sub.n, allowing this wavelength to pass and not allowing the other wavelengths λ.sub.n′≠n forming the composite laser beam 43 to pass;

(27) N power amplifiers 425, each power amplifier receiving the electrical signal coming from a photodiode 423;

(28) N antennas 426 disposed in a network to form a beam at the frequency

(29) $f=\frac{\omega }{2\pi }$
from the electrical signals generated by the electrical signal generator 411, each antenna 426 being powered by the output of a power amplifier 425;

(30) electrical energy supply and utility circuits, not represented in FIG. 4.

(31) FIGS. 5 to 7 illustrate the principle of operation of the correction device with which the radiant panel radio stimulation device according to the invention is equipped.

(32) In the context of FIGS. 5 to 7, for the purposes of simplifying the illustration, the matrix of photodiodes 423 is represented in the form of a planar structure on which the photodiodes are distributed regularly in rows and columns.

(33) This disposition, which makes it easier to understand the invention, is used hereinbelow in the text to describe the principle of operation thereof. It should not however be considered as a limiting feature, any other arrangement of photodiodes making it possible to pick up all the components of the composite laser beam 43 being able to be implemented in the context of the invention.

(34) It should however be noted that, from a hardware point of view, the matrix of photodiodes 422 in principle has a certain size, due to the fact that it is necessary to space apart the photodiodes 423 for them to be able to be illuminated adequately by the composite laser beam 43.

(35) As FIG. 5 shows, the path D.sub.n′ of the composite laser beam from the point M on leaving the aimed optic 417 to a given photodiode situated at the point P.sub.n of the plane (xOz) of the matrix 422 depends on a reference distance D from the point M to a point O of the matrix of photodiodes taken as reference, the center of the matrix for example, and on the spatial angular orientation (α,β) of the reference direction OM relative to a reference direction of the matrix of photodiodes 422, the axis (Ox) for example.

(36) Given the relative positioning of the subassemblies 41 and 42 forming the device according to the invention, the paths D.sub.n′ culminating at the set of photodiodes have lengths which are not strictly identical.

(37) These length differences are due, firstly, to the spatial angular orientation (α,β) of the composite laser beam 43, and, secondly, to the distance D which may not be sufficiently great relative to the size of the matrix of photodiodes for its contribution to the path length differences D.sub.n′ to be able to be disregarded.

(38) These path length differences D.sub.n′ are reflected by path-length differences δ.sub.n=D.sub.n′−D of different values for each photodiode 423. The result in a delay of the modulated laser signals which varies from one photodiode to the other depending on the position of the photodiode considered in the matrix 422.

(39) Consequently, they induce phase-shifts Δφ.sub.n[deg]1,2f.sub.[GHz].Math.δ.sub.n[mm] on the electrical signals detected by the matrix of photodiodes 422 which are added ultimately for each signal to the phase corresponding to the phase law created at the origin and emitted by the aimed optic 417.

(40) It should be noted that a simple numeric application makes it possible to confirm that these stray phase-shifts are not negligible.

(41) Thus, for example, for an electrical signal, of 10 GHz frequency, carried by the laser beam 43, a path length difference of 10 mm creates a phase-shift of 120°.

(42) Consequently, to obtain the desired phase law {Δφ.sub.n}, the function of the correction module 45 according to the invention is to generate the phase law {Δφ.sub.n} induced by the path-length differences δ.sub.n=D.sub.n′−D, from the measurements of D, α and β supplied by the measurement module 44 and to determine the phase law {Δφ.sub.n′}, equal to {Δφ.sub.n−Δφ.sub.n}, to be generated at the generator 411.

(43) Generally, the corrected phase law {Δφ.sub.n′}, is given by the relationship:

(44) $\begin{array}{cc}{\mathrm{\Delta \phi }}_n^{\prime }={\mathrm{\Delta \phi }}_n-2\pi \frac{f_s}{c}.Math.{\delta }_n& \left[001\right]\end{array}$

(45) In the particular case illustrated by FIGS. 5 to 7, the photodiodes responsible for detecting the composite laser beam are located placed in the plane (xOz) on which their positions P.sub.n are registered in terms of polar coordinates by the distance d.sub.n′ between the point P.sub.n and the reference point O and by the angle γ.sub.n′ that the segment OP.sub.n forms with the reference axis (Ox), as FIG. 6 illustrates.

(46) The path-length difference δ.sub.n is therefore given, in this case, by the following relationship:

(47) $\begin{array}{cc}\begin{array}{c}{\delta }_n=D_n^{\prime }-D\\ =D.Math.\left(\sqrt{1-2\left(\cos {\gamma }_n^{\prime }\cos \mathrm{\beta cos\alpha }+\sin {\gamma }_n^{\prime }\sin \beta \right)\left(\frac{d_n^{\prime }}{D}\right)+{\left(\frac{d_n^{\prime }}{D}\right)}^2}-1\right)\end{array}& \left[002\right]\end{array}$

(48) Consequently, for a desired phase law {Δφ.sub.n}, the corrected phase law {Δφ.sub.n′} to be emitted is given by the following relationship:

(49) $\left[003\right]{\mathrm{\Delta \phi }}_n^{\prime }={\mathrm{\Delta \phi }}_n-2\pi f_s\frac{D}{c}\left(\sqrt{1-2\left(\cos {\gamma }_n^{\prime }\cos \mathrm{\beta cos\alpha }+\sin {\gamma }_n^{\prime }\sin \beta \right)\left(\frac{d_n^{\prime }}{D}\right)+{\left(\frac{d_n^{\prime }}{D}\right)}^2}-1\right)$
in which D, α and β represent the unknowns.

(50) In order to have measurements of D, α and β, the measurement module 44 therefore performs, for at least three non-colinear points C.sub.1, C.sub.2 and C.sub.3 of the plane (xOz) of the matrix of photodiodes 422, the measurements of the distances D.sub.1, D.sub.2 and D.sub.3, separating these points from the point M of emission of the composite laser beam 43.

(51) Consequently, if these points C.sub.n are registered in the plane (xOz) by the distance d.sub.n and the angle γ.sub.n, as FIG. 7 illustrates, it is demonstrated that D, α and β are given by the following relationships:

(52) $\begin{array}{cc}D=\frac{\sqrt{\frac{d_2{d}_3\left(D_1^2-d_1^2\right)\left[\cos {\gamma }_2\sin \left({\gamma }_1-{\gamma }_3\right)-\cos {\gamma }_3\sin \left({\gamma }_1-{\gamma }_2\right)\right]}{d_3\left(d_2\cos {\gamma }_2-d_1\cos {\gamma }_1\right)\sin \left({\gamma }_1-{\gamma }_3\right)-d_2\left(d_3\cos {\gamma }_3-d_1\cos {\gamma }_1\right)\sin \left({\gamma }_1-{\gamma }_2\right)}+}}{\frac{d_1\cos {\gamma }_1\left[d_2\left(D_3^2-d_3^2\right)\sin \left({\gamma }_1-{\gamma }_2\right)-d_3\left(D_2^2-d_2^2\right)\sin \left({\gamma }_1-{\gamma }_3\right)\right]}{d_3\left(d_2\cos {\gamma }_2-d_1\cos {\gamma }_1\right)\sin \left({\gamma }_1-{\gamma }_3\right)-d_2\left(d_3\cos {\gamma }_3-d_1\cos {\gamma }_1\right)\sin \left({\gamma }_1-{\gamma }_2\right)};}& \left[004\right]\end{array}$$\begin{array}{cc}\beta =\mathrm{Arcsin}\frac{\left(d_1^2+D^2-D_1^2\right)d_2\cos {\gamma }_2-\left(d_2^2+D^2-D_2^2\right)d_1\cos {\gamma }_1}{2d_1{d}_{2}D\sin \left({\gamma }_1-{\gamma }_2\right)}& \left[005\right]\end{array}$$\begin{array}{cc}\alpha =\mathrm{Arc}\cos \frac{\frac{d_1^2+D^2-D_1^2}{2d_{1}D}-\sin {\gamma }_1\sin \beta }{\cos {\gamma }_1\cos \beta }& \left[006\right]\end{array}$

(53) According to the invention, the distances D.sub.n can thus be measured by any appropriate measurement means known from the state of the art, such as, for example, laser rangefinding measurement means such as the laser distance meters sold on the market and having accuracies of the order of a millimeter.

(54) However, in a preferred embodiment of the invention, the measurements are performed by means of the composite laser beam 43, which advantageously makes it possible not to have particular equipment to produce the measurement module 44.

(55) From a hardware point of view, it should be noted that the points C.sub.n chosen to measure the distances D.sub.n can coincide with points P.sub.n on which photodiodes are positioned. Indeed, the matrix of photodiodes is provided at the points P.sub.n with filters each allowing one of the wavelengths λ.sub.n to pass.

(56) Now, these filters can advantageously be catadioptric reflectors for wavelengths different from λ.sub.n′≠n such that it is still possible to use the composite laser beam to perform the measurements of the D.sub.n.

(57) It should be noted that, because the device according to the invention comprises two completely separate subassemblies and the transmission of the phase law generated by the signal generator subassembly 41 is transmitted to the emission subassembly 42 by means of a composite laser beam aimed toward the latter using an aiming optic 417, the theoretical structure of the invention as illustrated by FIG. 4 can be extended to structures implementing two or more emission subassemblies arranged facing the signal generator subassembly 42.

(58) Indeed, the aimed optic 417 of the signal generator 41 can be configured to direct a composite laser beam with an orientation from one panel to the other sequentially, the amplitude-phase law carried by the laser beam 43 being able to be different.

(59) Thus, one and the same optical carrier amplitude-phase law signal generator 41 can control several emission subassemblies 42 to make them radiate different signals in different directions according to an appropriate sequencing, the phase laws associated with each of the emission subassemblies being the subject of a particular correction by the correction system of the device.

(60) FIG. 8 offers a schematic representation of a radiant panel radio stimulation device according to the invention comprising two emission subassemblies 42a and 42b.

(61) It should be noted that, contrary to what might be thought from the functional schematic representation of FIG. 4, the matrix of photodiodes with filters 422 does not, in the context of the present invention, occupy any particular position with respect to the emission modules 421. In particular, the matrix of photodiodes 422 is not necessarily placed on the face of the structure formed by the emission modules 421 opposite the radiating face thereof. The relative positioning of the matrix of photodiodes and of the emission modules is more generally linked to the constraints relating to the application considered.