The invention relates to a method for controlling the electromagnetic compatibility of a radar sensor having at least one transmitter edge pulse signal. The invention also relates to a radar sensor and an associated platform.
A platform is a hardware entity used especially in the military field. A ship, an aircraft, a land vehicle, an earth ground station or a space station are examples of such platforms.
The platforms are equipped with radar detectors and airborne radar.
radar detectors have the function of receiving and detecting the radar signals while airborne radars emit radar signals.
In some situations, the radar detector receives pulses from airborne radar.
Indeed, the study of the pulse received by a detector radar from an edge of radar shows that the received pulse, a direct component and the reflected components.
The direct component is due to the propagation of the pulse transmitted between the radar antenna and that the radar sensor, according to the shortest path. The direct component therefore arrives at the radar warning receiver delayed from the transmitted pulse, but first in relation to others that are reflected.
The reflected components are due to reflections of the transmitted pulse on all material objects reflecting the environment. Different types of objects reflectors can be distinguished according to their proximity to actors (antenna board radar antenna and the radar sensor). In the order of increasing distance, the first type corresponds to the reflective surfaces of the supporting platform in visibility of actors (for example a ship superstructures, a barrel), the second type corresponds to the earth's surface (primarily the sea or earth to a certain extent) serving continuously to the radio horizon, and the third type corresponds to the particular reflecting surfaces of finite dimension bounded in the direction of propagation,
Thus, the presence of airborne radar thus interfere with the operation of the radar warning receiver, either via the direct component and the reflected components of the first, second or third type.
It is therefore desirable that the operation of radar detectors is compatible with the airborne radar. This problem is usually called electromagnetic compatibility (EMC abbreviated with the acronym).
For this, it is known to use effective mitigation throughout the reception frequency band of the radar detector. Such attenuation is, for example, performed by a PIN diode (English Positive Intrinsic Negative) then serving switch.
However, such a mitigation involves cutting all the reception during discomfort phases, which reduces the probability of intercept radar warning on the radar signals of interest.
There is therefore a need, in the context of a platform equipped with a radar sensor and at least one emitter edge pulse signals, a method for control of electromagnetic compatibility ente the radar warning receiver and each emitter edge that is more efficient.
the subphase comprising acquiring signals from the pulses emitted by the onboard transmitter considered and each corresponding to the edge component to obtain the detected pulse, and the acquisition of pulse characteristics measurements detected. The method comprises a subphase of calculation having the distribution of the detected pulses in classes with pulses where at least two features are of a common range of values, and selecting the class having a number of pulses greater than or equal to a threshold predetermined to give the selected classes and an elimination phase comprising the construction of a field of disposal, domain removal being the set of
According to particular embodiments, the method comprises one or more of the following features, (s) alone or according to all technically possible combinations:
- under-calculation phase is implemented twice, the distribution in the first implementation of the sub-phase calculation using raw features, the distribution in the second implementation of the sub-phase calculation using the second characteristic, the first and second characteristics and being distinct classes selected for the elimination phase being the classes selected for the first implementation of the calculation sub-stage and the selected classes in the second setting implementation of the sub-phase calculation.

- at each sub-phase calculation, the number of characteristics is less than 5.

- each sub-step of calculating comprises a group of classes by using a distance criterion between two classes.
- the radar detector comprises an attenuator, elimination is implemented by use of the attenuator preventing detection of pulses belonging to the field of disposal.
- the radar detector comprises a computer, the elimination being implemented by the computer by removing the detected pulses belonging to the field of disposal.

- each transmitter edge is adapted to generate a synchronizing signal, learning and elimination phases being timed with the synchronization signal of each transmitter board.
- under-acquisition phase involves the formation and use of areas of acquisition.
- the distribution is implemented using a histogram.
the characteristics comprising at least the date of arrival of the pulse in question and the carrier frequency of the pulse in question, the subphase having signals from the acquisition of the pulses transmitted by the onboard transmitter considered and each corresponding to the component edge, to obtain the detected pulse, and the acquisition characteristics detected pulses measures. The method comprises a subphase of calculation having the distribution of the detected pulses in classes with pulses where at least two features are of a common range of values, and selecting the class having a number of pulses greater than or equal to a threshold predetermined to obtain the selected clusters, and a phase of

The description also relates to a platform equipped with a radar detector as described above.
Other features and advantages of the invention will become apparent from reading the following description of the invention embodiments, given by way of example only with reference to the drawings, which are:
- Figures 1-8 are diagrammatic representations of signals to a first case;

- Figures 9 to 16 are diagrammatic representations of signals to a second case;
- Figures 17 to 24, schematic representations of signals for a third case;
- Figure 25 is a diagrammatic representation of an exemplary own radar detector to implement a method for control of electromagnetic compatibility between receptors pulse signal and edge pulse signal transmitters, and
- Figures 26 to 32, functional schematic diagrams of an exemplary implementation of the control method in several distinct stages.
There is provided a platform comprising a plurality of pulse signals of transmitters edge 2 and at least one radar sensor 4.
Before detailing the components of the radar sensor 4, there is described the disturbing environment wherein work is brought to the radar warning receiver 4 with reference to Figures 1 to 24.
Figure 1 shows the envelope of the transmitted pulses designated ie, these pulses are recurrent.
2 shows the envelope of the received signal s by a radar detector 4 as a result of the emission of the pulse ie.

Figures 3 to 6 represent the envelopes of the four physical components forming the signal received s.

3 shows the envelope of the direct component, the direct component being designated by scd.

4 shows the envelope of the component reflected by the supporting platform elements. Such a component is called reflected component edge.

The reflected component edge is designated by reference numeral CRSB.

5 shows the envelope of the component reflected by the earth's surface. Such a component is called clutter. The clutter is designated by the sign of serf reference.

6 shows the envelope of the reflected component on the outer individual items. Because of the similarity with the radar echoes, the reflected component on the outer isolated objects is designated by the sign of scre reference.

In Figure 6, for example, only two echoes are shown.

7 shows a synchronization signal of an airborne radar issued by itself. The synchronization signal is designated by the sign of SRBE reference.

In the example shown, the SRBE synchronization signal temporally overlaps the transmitted pulse ie. Therefore, a first time interval τ 1 and a second time interval τ 2 can be defined.

The leading edge of SRBE synchronization signal is ahead of a first time interval τ 1 with respect to the start time of the transmitted pulse ie.

The trailing edge of SRBE synchronizing signal is delayed by a second time interval τ 2 with respect to the end time of the transmitted pulse ie.

8 shows a signal corresponding to SRBE synchronization signal which arrives at the radar detector 4 after being propagated in a transmission cable. The incoming signal is designated by the sign of srb reference.

The transmitted signal SRB is delayed by a third time interval τ 3 relative to SRBE synchronization signal.

The fourth time interval τ 4 is defined as the time delay between the beginning of the received signal s and the leading edge of SRBE synchronization signal.

It should be noted that the difference between the fourth and third time intervals τ 4 - τ 3 corresponds to notice that the leading edge of the signal transmitted srb supply in relation to the actual discomfort, it is appropriate that this notice is sufficiently large and positive for it can be used (typically at least several hundreds of nanoseconds).

A fifth time interval τ 5 is defined as the time interval between the leading edge of SRBE synchronization signal and arrival date, the later of pulses reflected by the edge type CRSB.

A sixth time interval τ 6 corresponds to the time interval between the leading edge of SRBE synchronizing signal and the passage of serf clutter in a non-disruptive power.

It is also defined a seventh time interval τ 7 and an eighth time interval τ 8 respectively corresponding to the starting times and end times of the first echo with respect to the leading edge of the synchronization signal SRBE. The ninth and tenth time intervals τ 9 and τ 10 correspond to the same time to the second echo.

Figures 1 to 8 illustrate the case where the transmitted pulse is sufficiently short (Figure 1), there is no temporal overlap between the direct component sed (Figure 3) and the reflected component of CRSB edge (Figure 4) , so that the received signal s has two pulses at the start of induction (Figure 2).

Figures 9 to 24 illustrate the case where the conditions are such that there is this temporal overlap materialized by the hatched area. In such a case, the radar detector 4 receives the vector combination of the direct component sed and the reflected component edge CRSB. Generally, the resulting envelope s is linked to the amplitude-phase relationship between the two signals. Figures 9 to16 illustrate a situation of these two signals in phase and Figure 17-24 a situation in opposition. This is only a non-limiting example because, under these amplitude-phase relations are neither known nor controlled. In fact, in some cases, the casing has one or more successive pulses. Moreover, the situation is complicated even more if several components reflected edge.

An example of radar detector 4 is shown in Figure 25.

The radar detector 4 comprises two parts: a receiver 6 wave radar and a computer 8.

The receiver 6 comprises N channels.

N is an integer greater than or equal to 2 when the receiver 6 is adapted to implement the goniometry.

According to another embodiment, the receiver 6 has a single channel.

In Figure 1, only three channels are represented: the first way, the nth channel and the N-th track. The presence of the other channels is indicated by dotted lines.

Each channel includes an antenna 10 followed by an attenuator 1 1 1 1 being the attenuator followed by a receive chain 14.

Each antenna 10 is capable of receiving a radio signal and outputting an electrical signal to the attenuator 1 1 from the received radio signal.

The set of antennas 10 allows the direction finding signals received by the antennas.

The attenuator 1 1 comprises a set of signal attenuation elements.

The presence of the attenuator 1 1 makes it possible to ensure electromagnetic compatibility.

The attenuator 1 1 comprises at least one switch 12.

Switch 12 is able to pass a signal or not.

According to a particular example, the switch 12 is controlled PIN diode bias by the blanking signal and providing an attenuation of between 40-60 dB.

According to the example of Figure 25, the attenuator 1 includes 1 / insertion devices 13 of a notch filter in series, each corresponding to the rejection of a suitable frequency range vis-à-vis the airborne radar with an attenuation of the order of 30 to 60 dB.

Each receiving chain 14 is adapted to deliver a signal so that all the receiving channels 14 is suitable for delivering in parallel N signals.

The calculator 8 is, for example, a set of digital components.

Alternatively, the computer 8 is a computer program product, such as a software.

The calculator 8 is able to implement the steps of a control method of the electromagnetic compatibility of the receiver 6 with the pulse signal edge emitters 2.

The operation of the radar sensor 4 is now described with reference to Figures 26 to 32 which show a schematic view of the control method in several distinct stages.

For this, the computer 8 is broken down into modules, this breakdown showing the different functions that the computer 8 is able to implement.

The ECU 8 includes a characterization module 15 pulses, a characterization module development and characterization of the tracks 17 and a compatibility module 22 interposed between the two modules 15 and 17.

The characterization module pulse 15 is adapted to analyze the N signals that the receiver 6 is able to deliver.

The characterization module pulse 15 is adapted to characterize each detectable incident radar pulse.

Such characterization is implemented using at least one measured quantities of the pulse.

A magnitude characteristic is also referred to in the following (hence the term pulse characterized).

In one example, the variable is the arrival of the pulse t, which is the arrival time dating the leading edge of the pulse.

According to another example, the variable is the amplitude of the pulse A.

In yet another example, the magnitude is the width of the pulse LI.

According to another embodiment, the quantity is the carrier frequency of the pulse /.

In yet another embodiment, the magnitude is the intended intra-pulse modulation IMOP (English Intentional Modulation is Drawn) and possibly unintended PIU (English Unintentional Modulation is Drawn) generally designated by the modulation intra -impulsion MOP.

According to another example, the magnitude is the direction of arrival Θ. For example, the arrival direction is characterized by the azimuth, that is to say the angle of arrival in the local horizontal plane referenced to true north. Alternatively, the direction of arrival is also characterized by the site, that is to say the angle of arrival in the local vertical plane with respect to the local horizontal.

According to another example, the magnitude is the polarization of the carrier wave pol. According to a particular example, the characterization is implemented using a plurality of measurements of quantities of the pulse, each measurement being chosen from the preceding examples.

For the following, it is assumed that the selected values ​​are the date of arrival of the pulse t, the amplitude of the pulse A, the width of the pulse LI, the carrier frequency of the pulse / the intra-pulse modulation MOP and the arrival direction Θ.

In addition, for the rest, each pulse is designated by the sign of reference IC k . k being an integer, the index k corresponding to the k-th detected radar pulse.

For the / c-th pulse radar detected, these values are multiplied by an index k, where writing IC k = (t k , A k , LI k , f k , MOP k , e k ).

The compatibility module 22 is suitable for implementing the control method. The method uses the pulses characterized IC k also designated by the reference character 16 corresponding to the airborne radar, to optimize the use of the attenuator 1 and 1 in order to eliminate the flux IC { k } hardcore pulses corresponding to radar edge and transmitting a pulse stream characterized filtered LCF { k } as designated by reference numeral 23 in the development unit and characterization of 17 tracks.

For this, the compatibility module 22 includes a plurality of modules visible in Figure 27. These modules are a module 40 for storing predefined size, a module 50 for measuring date of arrival, a module 60 forming areas, a module 70 for comparing a pulse characterized with a domain, a module 80 for storing the pulses characterized recalibrated, a module 90 for calculating a module 100 for storing calculated values, a module 1 10 removing characterized and a pulse module 120 for developing blankings.

The pulse stream characterized IC { k } is processed by a development module and characterization of the tracks 17, the tracks 18 being objects synthesizing all the characteristics of the radar noticeable over time (recurrence, antenna radiation modulations various).

We will now detail with reference to Figures 27 to 32 the checkout process.

The method comprises two phases, namely a learning phase and a removal phase.

The two phases are clocked by different timing signals of airborne radar.

The learning phase is operable to acquire a precise characterization of the signals from the pulses emitted by the radar through the edge pulses characterized IC k to form areas of elimination to precisely control the elimination phase, the pulses characterized IC k being selected areas through acquisition.

The learning phase is implemented for each board radar.

The learning phase comprises three sub-steps of acquiring a first sub-stage of acquiring the edge component (mixture of the direct component scd and reflected component edge CRSB), a second subphase

acquisition of the reflected component of serf clutter and a third sub-stage of acquiring the reflected component on external objects scre isolated.

Each of the three sub-phases comprises a first pulse acquisition step characterized IC k and a second calculating step.

Figures 28-30 respectively correspond to the three sub-phases of acquisition. In each of the figures, appear the functions used in thick lines and payload decorated with an arrow to indicate the path, shaded to those used in the early stages of acquisition and full black to those used for the second calculation steps .

For each radar edge, each first acquisition step is clocked by the synchronizing signal from the onboard radar considered sr.
Each first acquiring step comprises measuring, training and comparison.
During measurement, it is measured arrival time t m i of the leading edge of the m-th pulse of SRBT synchronizing signal of the i-th on-board radar. Such measurement is implemented by the date of arrival measurement module 50, consistent with the arrival measured by the pulse characterization module 15 located upstream in the radar sensor 4, that is ie with the same origin, time resolution and measurement accuracy.
Upon formation, there is formed a capture range DA m i specific to each sub-phase, and for this m-th pulse of SRBT synchronizing signal of the i-th on-board radar. Training is implemented by the training module of 60 areas.
When comparing the pulses characterized IC k incident are compared to the domain acquisition DA m i . The comparison is implemented by the comparison module of a pulse characterized with field 70.

WE CLAIMS

1. - A method of controlling the electromagnetic compatibility of a radar warning receiver (4) with at least one edge emitter (2) of pulse signals, the radar warning receiver (4) and each transmitter of edge (2) of the same platform, by removal of the edge component in the signals received by the radar warning receiver (4), the edge component corresponding to the mixture of the direct component and the reflected component edge, the method comprising:
- a learning phase comprising, for each transmitter board (2):
- a sub-phase acquisition to obtain detected pulses, each pulse being characterized by features, the characteristics comprising at least the date of arrival of the pulse in question and the carrier frequency of the pulse in question, under the - phase comprising:
- acquisition of signals from the pulses emitted by the on-board transmitter (2) in question and each corresponding to the edge component, to obtain the detected pulses, and
- acquiring the pulses detected characteristics measurements,
- a sub-step of calculating comprising:
- the distribution of the detected pulses in classes with pulses where at least two features are of a common range of values, and
- selection of classes having a number of pulses greater than or equal to a predetermined threshold for the selected classes, and
- an elimination phase comprising:
- the construction of a field of elimination, a field of elimination being the set of pulses detected by the radar warning receiver (4) belonging to the selected class, and
- elimination in the signals received by the radar warning receiver (4) of pulses belonging to the field of disposal.
2. - The method of claim 1, wherein the sub-step of calculating is carried out twice, the distribution in the first implementation of the sub-phase computation using the first characteristics, the distribution at the second implementation of the sub-phase computation using second characteristics, the first and second characteristics and being distinct classes selected for the elimination phase being the classes selected for the first implementation of the sub phase calculation and the selected classes in the second implementation of the sub phase calculation.
3. A process according to claim 1 or 2, wherein, in each sub-step of calculating the number of characteristics is less than 5.
4. A process according to any one of claims 1 to 3, wherein, each sub-step of calculating comprises a group of classes by using a distance criterion between two classes.
5. - Method according to any one of claims 1 to 4, wherein the radar warning receiver (4) comprises an attenuator (1 1), the elimination is implemented by use of the attenuator (1 1) preventing detection of pulses belonging to the field of disposal.
6. - Process according to any one of claims 1 to 4, wherein the radar sensor (4) comprises a computer (8), the removal being carried out by the computer (8) by removal of the detected pulses belonging to the field of disposal.
7. - Method according to any one of claims 1 to 6, wherein each transmitter board (2) is adapted to produce a synchronizing signal, learning and elimination phases being clocked with the signal synchronizing each transmitter board (2).
8. - Process according to any one of claims 1 to 7, wherein the sub-acquisition phase involves the formation and use of domain acquisition.
9. - Radar detector (4) comprising a receiver (6) of electromagnetic waves and a computer (8), the radar warning receiver (4) being configured to implement a method for controlling the electromagnetic compatibility of the detector radars (4) with at least one transmitter of edge pulse signals, the radar sensor (4) and each transmitter board of the same platform, by removal of the edge component in the signals received by the detector radars, the edge component corresponding to the mixture of the direct component and the reflected component edge, the method comprising:
- a learning phase comprising, for each transmitter board:
- a sub-phase acquisition to obtain detected pulses, each pulse being characterized by features, the characteristics comprising at least the date of arrival of the pulse in question and the carrier frequency of the pulse in question, under the - phase comprising:
- acquisition of signals from the pulses emitted by the onboard transmitter considered and each corresponding to the edge component, to obtain the detected pulses, and
- acquiring the pulses detected characteristics measurements,
- a sub-step of calculating comprising:
- the distribution of the detected pulses in classes with pulses where at least two features are of a common range of values, and
- selection of classes having a number of pulses greater than or equal to a predetermined threshold for the selected classes, and
- an elimination phase comprising:
- the construction of a field of elimination, a field of elimination being the set of pulses detected by the radar warning receiver (4) belonging to the selected class, and
- elimination in the signals received by the radar warning receiver (4) of pulses belonging to the field of disposal.
10.- platform equipped with a radar warning receiver (4) according to claim 9.