DE3520310C2 - Procedure for eliminating the ambiguity of distance as well as transmitter in a pulse Doppler radar device and receiver for performing this procedure - Google Patents

Description

The invention relates to a method for eliminating distance ambiguity in a pulse doppler radar device as well an apparatus for performing this method.

A special property of the radar systems is the Ent distance ambiguity. The distance ambiguity is caused by the fact that a radar can't differentiate between a goal in one Distance D and a target at a distance D modulo, where TR is the subsequent period or repetition  period of the radar system and C the speed of light is.

So the maximum clear distance is.

A second peculiarity that occurs with radar systems is the speed ambiguity. This particularity is caused by the fact that a radar system cannot distinguish between a target whose radial speed is V _R and a target whose radial speed is V _R modulo, where λ is the transmission wavelength. The Doppler frequency F _D is consequently measured up to a multiple of the repetition frequency F _R : F _D = f ′ _D + kF _R , where f ′ _{D is} the actual Doppler frequency and k is an integer.

The distance ambiguity and the speed Ambiguity are two interdependent parameters. For a given transmitter frequency, there is an increase the still clearly recorded range to a min change of the still clearly recorded speed area.

In certain applications, especially radar systems with medium or long range (D ≧ 100 km), the be used in air monitoring, it is not essential, the real distance without more to recognize clarity. With the usual broadcasting bands (L, S, X) leads the speed range from Aircraft to a range / Doppler ambiguity.

For practical and technical reasons (density and Fixed echo dynamics, phase stability error of the Channel, . . .) So far, the choice has always been striking the still clear distance range under buying  taking a speed ambiguity. The development However, technology has made it possible (use of solids pern in the transmitter, 3D antenna with low side peaks,. . .), to work in the area of distance ambiguity.

With a pulse Doppler known from FR 24 12 852 A1 Radar is used to resolve range ambiguities a sequence of pulse packets sent into multiple blocks different pulse repetition frequency are divided. Wuh The pulse train remains free for the duration of each pulse packet quenz constant. The transmission signal corresponds to a sequence of pulse blocks sent simultaneously. But this presupposes from the fact that as many transmitters and reception branches as at the same time pulse blocks to be sent must be available. The on Resolving the distance ambiguity also requires the combined processing of several consecutive Impulse packet sequences.

The invention has for its object a simpler Ver drive to resolve the ambiguity of distance, where the resolution of the ambiguity is already in one single pulse packet sequence is possible.

This object is achieved by the in claim 1 specified procedures solved. Advantageous further developments of the Procedures are specified in the subclaims.

In the method according to the invention, pulse packets with a repetition frequency f _R and a transmission frequency f are emitted, which are predetermined for each pulse packet. The impulse packets consist of parts that differ from one another by a phase law that is imposed on the transmission side and on the reception side that enables an apparent Doppler frequency to be obtained that is proportional to the ordinal number of the target that was acquired, whereby the term ordinal number means the number of the repetition sequence during which the goal first appeared.

The invention also provides a device for Implementation of this procedure created. The transmitter this device is essentially characterized in that it has a video signal generator and a phase shift operator for complex phases rotation through which the with each pulse desired phase rotation can be caused. Of the Receiver of the device is essentially characterized in that he has an assembly to correct the distance more contains clarity that has a phase operator, followed by a Doppler processing circuit which in turn is a circuit to fix the distance ambiguity follows.

Several embodiments of the invention result from the following description and from the drawing to which reference is made. In the drawing shows:

Fig. 1 is a general block diagram of ambiguity of a transmitter / receiver for implementing the method to eliminate the distance;

Fig. 2 is a block diagram of a circuit to correct the range ambiguity in accordance with a first embodiment; and

Fig. 3 is a circuit diagram of a circuit for eliminating the distance ambiguity according to a second embodiment.

The invention is applied to a radar system, the Operating data are such that the irradiation time for one point target Te is. In conventional operation without ambiguity the number of targets becomes illuminations by this radar system by the following Relationship determines:

The invention is particularly concerned with conventional ones Pulse radar systems as well as with Doppler radar systems and radar systems operating with pulse compression.

A radar system sends out pulse packets. This transmission principle consists in sending out pulse trains with the transmission frequency f and a repetition frequency f _R , which are determined for each pulse packet (the frequencies can be different for each packet).

The method consists in choosing a range ambiguity factor P for this radar system which meets the criterion sought, which is given by the ratio between the desired detection range D and the ambiguity range D _A (P = integer).

By choosing an ambiguity factor P, i.e. H. if the acquisition extends over P repetition sequences is the number of target illuminations B2 = P.B1.  

The method on the transmission side is that a number I of pulses per pulse package is selected, which is equal to N ver increases by the ambiguity factor and multiplied with k, where k is an integer I = k, with I = k (N + P). The number k enables k parts to be N + P To form impulses.

Each package contains a first part, which consists of There are impulses for which the original phase is the same is a constant, as well as (k-1) parts, each consisting of N + P packets exist for which the origin phase quadratic multiple of the atomic number of the pulse is in the part under consideration.

In a first embodiment, k = 2 is chosen.

Different parts are used for the two parts of the pulse package Phase laws applied.

Each impulse comes with a different phase of origin sent. With is the phase term of an impulse with the index n, which is the atomic number a pulse in one of the two parts of the pulse packet designated.

A first part of the package contains the impulses, their Index is such that n = 0, 1,. . ., (N + P-1). These impulses are sent with the phase disappearing, so that the Phase term is:

A second part of the package includes the pulses, their Index n is such that:

n = N + P, N + P + 1,. . ., 2 (N + P) - 1.

These pulses are sent with a phase that is 2πm, where m is an integer and Q can be arbitrary and denotes the number of filters. So the phase term is:

Digital Doppler filtering can be done by calculation with direct processing of the complex video signal done, the operation on the N samples of the signal is expanded.

The Doppler measuring accuracy is then f _R / N = f _C ; in this case, one is content to use filters at a distance of Δf _D , which are centered on the values f _Di = if _R / N, i [O, N].

In this case, the phase shift Φ _{n of} the pulses of the second part of the pulse packet is

According to a preferred embodiment, a filter number Q is selected, Q being arbitrary (for example Q = 2N). The Doppler measurement accuracy is f _R / Q. The filters are based on the values f _i = if _R / Q, i [0; Q] centered. In the second part of the package, the phase shift Φ _{n is the} same.

The choice of a filter number Q instead of a number N enables it to improve the filtering so that the Pass filter curve the spectral density of the noise with which the signal is afflicted. Each filter has such a pass function H (f) that:

where X (f) is the amount of the discrete Fourier transform is the signal and Φ (f) is the spectral density of the Interference components (noise, clutter,...), Which with the Signal are mixed.

The phase of each pulse remains throughout Receive duration. The signal sent in the baseband can be written as follows:

Here x (t) is the signal in the baseband, which in the case of a radar system with pulse compression also as "long Pulse ". This signal is then in implemented several stages on the transmission frequency f.

Upon receipt, the delay of a destination to which the ordinal number p belongs and which has therefore appeared in the p + 1th repetition sequence, based on a destination with the ordinal number 0, is tp, so that tp = to + p T _R.

That in the course of the nth repetition sequence of a Part of the pulse packet from a single point-like target Atomic number p received signal is given by equation (1) given;

In it f _{D is} the normalized Doppler frequency, which is the ratio of the true Doppler frequency to the repetition frequency.

The term a _o x (t - t _o ) represents the amplitude of the received signal, where a _o corresponds to the attenuation and t _{o to} the pure delay, which depends on the distance between the target and the radar system.

The term represents the constant phase shift for any repetition order.

The term is the phase term of the target with the order number p. This term is with the transmitting phase law connected.

The term is the one dependent on the Doppler frequency Phase term (the Doppler component in the pulse is ver neglected).

At the receiving end, the procedure is the same Phase correction term based on the phase of the received Apply signals, no matter what atomic number belongs to it. This correction is done by the inverse Phase of the transmission signal is applied, ie if the phase of the transmitted signal was.

The equation of that received from the target of atomic number p So the signal is:

The Doppler frequency f _D remains unchanged for the pulses whose phase on the transmission side was set to 0 (nε [0; N + P]), regardless of the ordinal number of the target.

For the impulses whose phase on the transmission side 2 m nε [N + P; 2 (N + P)] has been set the signal after correction for a target of ordinal p following measure:

The term

is a pure phase shift, not of interest for the subsequent processing is while the term

reveals a frequency deviation, namely an apparent Doppler frequency f _DA . This frequency is written as follows:

modulo f _r , f _e is the transmission frequency.

With this method, the Doppler frequency for the impulses that form the second part of an impulse packet, shifted by a frequency proportional to Is an atomic number.

In order to obtain the apparent Doppler frequency f _DA and the Doppler frequency f _D , Doppler processing is carried out, which is the same for both parts of the pulse packet. This processing consists of the following:

• - the P initial pulses are removed for each pulse packet;
• - Doppler processing is performed, which is applied to N pulses of the first part and the second part of the packet. Q filters are formed, each of which has a different maximum i / Q f _r .

Shifting the Doppler frequency by causes the apparent Doppler frequency f _{DA to be} in a different filter than f _D , and m is a large enough integer to shift the frequency f _DA by an integer number of filters to a filter outside of that Filter lies in which there can be a signal that originates from a target and leads to a Doppler frequency f _D. Information present in a filter i, where i can be between 0 and Q-1, is thus found in a filter i ′ = (i-2mp) modulo Q.

X _{i, 1} denotes the discrete Fourier transform of the received signal over N pulses of the first considered pulse packet part. In detail follows

X _0.1 . . . X _N-1.1 ; iε [0; Q].

X _1,2 denotes those filters that make it possible to process the discrete Fourier transform via the N pulses of the second pulse packet part. X _0.2 results in detail. . . X _N-1.2 .

After filtering, the amount is calculated for each filter; X _{i, 1} is the amount for X _{i, 1} and Y _{i, 2 is} the amount for X _{i, 2} , ie:

Y _{i, 1} = | X _{i, 1} |

Y _{i, 2} = | X _{i, 2} |

The method for eliminating the distance ambiguity then consists in applying a shift of 2mp to the discrete Fourier transform of the pulses of the second pulse packet part for each atomic number p (p = 0, 1... P-1); Z _{i, p} is the amount of the Fourier transform after displacement:

Then the sum Σi, p and the difference Δi, p in absolute value from filter to filter between the two discrete Fourier transforms for each atomic number p educated:

Σ _{i, p} = Y _{i, 1} + Z _{i, p}

and

Δ _{i, p} = Y _{i, 1} - Z _{i, p}

A first detection threshold value SΣ, which guarantees a false alarm probability Pf _a , which corresponds to the usual criteria, and a second detection threshold value SΔ, which ensures a high false alarm probability compared to conventional criteria, are now defined.

In a first case, if Σ _{i, p} <SΣ, it is assumed that a detection DΣ _{i, p took place} after the first threshold value, otherwise no detection has taken place. In a second case, if Δ _{i, p} <SΔ, it is assumed that a detection DΔ _{i, p was made} after the second threshold.

The extraction criterion for a target is obtained if in the first case registration and in the second case no registration took place.

It is decided that a target of atomic number p for a filter i is present if the following condition is satisfied:

The method described enables the distance Fix ambiguity if only one goal is present in the removal window. With strong sturgeon echoes for the first atomic number, in particular fixed echoes, can the danger of the useful echo being covered by the sturgeon echo can be eliminated by dividing the pulse package into three parts is divided.

In this case there will be a number of pulses (k = 3), I = 3 (N = P) sent per pulse packet. A first one Part contains the pulses for which nε [0, N + P], a second part contains those impulses for which nε [(N + P), 2 (N + P)], and a third part those for which nε [2 (N + P), 3 (N + P)].  

The ambiguous distance processing In the same way, speed consists of a certain Send the phase law on each of the three parts of each pulse packet to use on the side, which makes it possible on the receiving side will get a shift in Doppler frequency which depends on the ordinal number of the target.

The use of three pulse packet parts makes it possible to frame the Doppler frequency f _D by two apparent Doppler frequencies f _DA and f ' _DA , the frequencies f _DA and f' _DA resulting from a shift in the frequency f _D by a value which is proportional to Atomic number D of the target is.

The pulses are used to frame the Doppler frequency of the first part with such a phase term  framed that:

A phase term applies to the impulses of the second part  = 1, and the impulses of the third part Phase term that:

The phase of each pulse is throughout Keep sending duration.

That in the course of the nth pulse of a pulse packet part of a single point target of the atomic number p received Signal is given by equation (1).  

The receiving process consists of the same phases correction terms regardless of the ordinal number of the target turn

So there will be a correction term for the first part each pulse packet, a term on the third part of each Pulse packets applied.

The apparent Doppler frequency for a target of atomic number p due to the impulses of the first part of the pulse package:

The apparent Doppler frequency for a target of atomic number p due to the impulses of the third part of the impulse package:

The Doppler frequency is determined by the second part of the Impulse package not changed.

Then the same Doppler processing for the three pulse packet parts performed as for a two-part Pulse package was described above.

The shift in the Doppler frequency around cause the frequencies f ' _DA and f _{DA to} be in the two filters on one or the other side of the filter in which the frequency f _D lies (shift by 2mp filter).

X _{i, 1} , X _{i, 2} , X _{i, 3} denote the discrete Fourier transform of the first, second and third part of a pulse packet, which are processed by filters with index i.

After filtering, the amount of the signals extracted from each filter is calculated; the amounts of X _{i, 1} , X _{i, 2} , X _{i, 3} are denoted by Y _{i, 1} and Y _{i, 2} and Y _{i, 3} , respectively. The method for eliminating the ambiguity in the distance then consists in performing a shift of -2mp for the first Fourier transform and + 2mp for the third Fourier transform.

Let Z _{i, p} be the amount of the Fourier transform after the shift by -2mp; W _{i, p} is the amount for the shift by + 2mp.

The sum Σ _{i, p} and difference Δ _{i, p} , in absolute value, are then formed from filter to filter between the discrete Fourier transforms in pairs:

Σ _{i, p} = Y _{i, 1} + Z _{i, p} and Σ _{i, p} = Y _{i, 2} + W _{i, p}

Δ _{i, p} = Y _{i, 2} + Z _{i, p} and Δ _{i, p} = Y _{i, 2} + W _{i, p}

A first sum detection threshold value is then defined for both cases, which is denoted by SΣ and ensures a false alarm probability P _fa , which is low compared to the usual criteria; Furthermore, a difference detection threshold value SΔ is set for both cases, which ensures a false alarm probability that is large compared to the usual criteria.

In both cases it is assumed that a sum detection DΣ _{i, p} or dΣ _{i, p} has taken place after the first threshold value if Σ _{i, p} <SΔ; otherwise no registration was made. In both cases it is further assumed that a difference detection DΔ _{i, p} or dΔ _{i, p was carried out} after the second threshold if Δ _{i, p} <SΔ; otherwise no registration was made.

The extraction subcriterion for a target is in receive both cases when in the first case an entry and in the second case, no detection took place Has.

It is then decided that a target of the atomic number p for a filter i, if:

D = D _{i, p} Ud _{i, p}

In Fig. 1, the general block diagram of a transmitter / receiver according to the inven tion is shown.

The receiver 1 has a video signal generator for a video signal x (t), which is illustrated by a block 2 . A rotary operator 1 enables the complex phase rotation desired for each pulse. The frequency of the signal is then converted and amplified in conventional circuits, which are illustrated by a block 4 . The signal is then fed to the antenna 5 via a duplexer 6 .

According to a particular embodiment, the transmitter 1 is suitable for delivering the pulses in packets, that is to say as a result of pulses of the given frequency f and with the repetition frequency f _R which is given for each pulse sequence. The N + P first impulses are delivered with a constant phase of origin and thus form the first part in each two-part package. The N + P further impulses are with the phase

delivered and form the second part of the package.  

Another embodiment is that the transmitter 1 is suitable for delivering the pulses in packets. The delivery of the two parts (in this embodiment) takes place practically simultaneously. For this purpose, every pulse with the phase

immediately afterwards to the impulse of the same atomic number and of given constant phase. To receive between to be able to distinguish between the impulses becomes the signal on the transmission side in the baseband with a pseudo orthogonal Code encoded. Under such a pseudo-orthogonal Such a code is understood that for a Signal x (t) of a pulse of the first part of the packet in the baseband and a signal x (t) of the pulse equal Atomic number from the second part of the package in the basic tied these two signals to obey the following relationship:

Here T is the duration of an impulse.

The receiver 7 comprises a group of amplifier and frequency conversion circuits of a conventional type and an amplitude-phase detector 9 , followed by a processing module 10 for eliminating the distance ambiguity. This ambiguity correction module 10 includes a rotation operator 11 to perform an inverse rotation to the transmission-side rotation, followed by a Doppler processing circuit 12 for obtaining the Doppler frequency. This circuit 12 is followed by circuits for eliminating the ambiguity in distance for the ordinal numbers p = 0, 2. . . P-1 that allow the acquisition decision criteria to be applied. A time base 14 controls transmit and receive operations.

In an embodiment in which the pulse packets are part for part are sent out on the receiving end Differentiation between the parts in particular by means of P initial or initiation impulses. In one execution with impulses of the parts delivered practically simultaneously A pulse packet distinguishes between the parts using pseudo-orthogonal coding. At this Embodiment are the discarded received ones Pulses for two in phase. The capture can therefore according to the sum and difference formation steps respectively.

FIG. 2 shows a first embodiment of a circuit 10 for eliminating the ambiguity. This imple mentation form enables the use of the imple mentation form, in which it is assumed that each pulse packet consists of two parts. The known phase rotation operator 11 is not shown.

The circuit 10 includes the Doppler processing circuit 12 , which in turn has a first operator 15 in this particular embodiment, which acts on the first part of each pulse packet. The operator 15 consists, for example, of Q double filters, whose pass function H (f) is the same

where the amount of the Fourier transform of the signal and Φ (f) is the spectral density of the interference signals. The output signal of a filter i among the Q filters is designated X _{i, 1} .

A second operator 16 enables the processing of the second part of the salvo. It also consists of Q Doppler filters. The output signal of a filter i among the Q filters is designated X _{i, 2} .

The operators 15 and 16 are followed by detectors 17 , 18 , which obtain the amounts X _{i, 1} and Y _{i, 2 of} the signals X _{i, 1} and X _{i, 2} .

For the sake of simplicity, only a single circuit 13 for eliminating the distance ambiguity is shown. This circuit enables the ambiguity to be eliminated for a target of the given atomic number p. There are as many circuits of this type as possible atomic numbers, ie P (p = 0, 1,... P-1). This circuit includes a translation circuit 19 and an extraction circuit 14 .

The shift is effected by the translation circuit 19 , which shifts the signal Y _{i, 2} , which represents the apparent Doppler frequency of a target detected during a p + 1-th repetition sequence, by a value of 2mp. The output signal of the translation circuit 19 is designated Z _{i, p} .

The extraction circuit 14 enables the decision criteria for the detection to be applied and contains a summer 20 and a subtractor 21 . The summer 20 forms the sum of the output signals of the detector 17 and the translation circuit 19 , that is to say Y _{i, 1} and Z _{i, p} , for emitting a sum signal Σ _{i, p} . The subtractor 21 forms the difference between these same signals in order to obtain a difference signal Δ _{i, p} .

A comparator 22 and a comparator 23 are connected to the output of the summer 20 or subtractor 21 . The comparator 22 receives the signal Σ _{i, p} and a threshold signal SΣ in order to compare the sum signal with this threshold signal and to emit a detection signal DΣ _{i, p} in this sum signal.

The comparator 23 receives the signal D _{i, p} and a threshold signal SΔ in order to compare this difference signal with this threshold signal _and to output a detection signal DΔ _{i, p} on this difference channel. At the output of the comparator 23 , an inverter 24 inverts the signal DΔ _{i, p} and outputs the inverted signal.

An AND gate circuit 25 receives the signals DΣ _{i, p} and and decides on the detection or non-detection, depending on the state of the output signal D _{i, p} .

FIG. 3 shows a second embodiment of the range ambiguity correction circuit 10 which is suitable for carrying out the embodiment in which it is assumed that each pulse packet consists of three parts.

The same elements have the same reference numerals.

A third channel has been added to the first embodiment to process the pulses of the third part. A third operator 26 acts on the third part of the pulse packet. In this embodiment, the operator consists of Q Doppler filters with the pass curves H (f). The output signal is designated X _{i, 3} . The amount Y _{i, 3 of} the signal X _{i, 3 is} obtained by a detector 27 .

As in the first embodiment, only a single circuit 13 for eliminating the ambiguity was shown, which relates to the removal of the ambiguity for a given ordinal number p. The circuit further comprises a translation circuit 19 and an extraction circuit 14 . The translation circuit 19 comprises two converters 29 , 30 , and the extraction circuit 14 contains two extraction modules 20 to 25 and 40 to 45 . The detector 27 is followed by the converter 29 , which shifts the signal Y _{i, 3} by a value + 2mp. The detector 17 is followed by the converter 30 , which shifts the signal Y _{i, 1} by a value -2mp. The converters 29 and 30 emit the signals W _{i, p} and Z _{i, p} .

The summer 20 and the subtractor 21 receive the signals Y _{i, 2} and Z _{i, p} . The circuits 22 to 25 ensure the same function as in the first embodiment.

The summer 20 and the subtractor 41 receive the signals Y _{i, 2} and W _{i, p} and output the signals Σ _{i, p} and Δ _{i, p ,} respectively. The comparators 42 and 43 receive these signals and compare them with the threshold values SΣ and SΔ; they emit the signals dΣ _{i, p} and dΔ _{i, p} , which make it possible to obtain a second criterion for partial detection. For this purpose, an inverter 24 inverts the signal dΔ _{i, p} to output a signal. An AND circuit 45 receives the signals dΣ _{i, p} and to deliver the signal d _{i, p} . An OR gate 50 receives the signals D _{i, p} and d _{i, p} to output the detection decision signal D.

The radar transmission / reception method thus it is possible to have a distance D To distinguish a goal from a goal that is defined in Ent distance is at least one in this way derive apparent Doppler frequency, which one Shift of the Doppler frequency corresponds to that per is proportional to the ordinal number of the target.

The Doppler processing allows it to be while the detection of a target of atomic number p the apparent Doppler frequency or apparent Doppler frequencies too gain that from the difference of the transmission side and receiving phase laws result and by Block-wise time shift of the echoes of the pth ordinal number against the echoes of atomic number 0 (where the ordinal number 0 is the first ordinal number in the usual way.

Claims (23)

1. A method for eliminating the distance ambiguity in a pulse Doppler radar device, in which pulses are sent in pulse packets and a given pulse repetition frequency f _R and a given transmission frequency f are used for each pulse packet, characterized in that
On the transmission side, such a phase law is applied that each pulse packet has a first part for which the phase is equal to a constant and (k-1) parts (k integer) for which the phase is a quadratic multiple of the ordinal number of the pulse in the part under consideration, and
the inverse phase law is applied at the receiving end and then a Doppler processing is carried out in order to obtain those Doppler frequencies which result from the different transmitting-side phase laws which occur during the detection of a target which occurs in a repetition sequence of the atomic number p of apparent Doppler frequencies which correspond to a shift in the Doppler frequency of the target proportional to the atomic number p. 2. The method of claim 1, wherein N pulses per pulse packet are sent, characterized in that a Ambiguity factor P is selected and the number of Im pulses per pulse packet equal to the sum multiplied by k is composed of N and P. 3. The method according to claim 1 or 2, characterized in that k = 2 and each part of a pulse packet N + P pulses contains. 4. The method according to any one of claims 1 to 3, characterized in that the transmission side, the pulses of the first part of the pulse packet are such that the phase term is 1, the index n varies between 0 and N + P - 1, and that the pulses of the second part of the pulse packet are such that the phase term is the same where m is a predetermined integer and n varies between N + P and 2 (N + P) - 1, while Q is an integer. 5. The method according to any one of claims 1 to 4, characterized in that a Doppler processing is applied on the receiving side to the N pulses, which follow the P pulses for each pulse packet part to the Doppler frequency f _{D of} the target of the atomic number p and the apparent To determine frequency f _DA , where f _{DA is the} same, that for each ordinal number the amount of the signals is obtained, which are obtained by the Doppler processing, and that for each ordinal number a shift is applied to the amount of the signal of the second pulse packet part and then the acquisition decision criteria are applied to each ordinal number. 6. The method according to any one of claims 1 to 5, characterized ge indicates that the decision-making criteria at the receiving end for each atomic number consist in that on the one hand a Sum formation and on the other hand a difference formation between the amount of the signal caused by the Doppler processing  the first part of the pulse packet is obtained, and the shifted NEN amount of the signal caused by the Doppler processing of the second part of the pulse packet is obtained, that a comparison of the sum signal obtained with a first predetermined threshold is made and that a Comparison of the difference signal obtained with a second one predetermined threshold is made, the criterion for the extraction or confirmation of a target will hold if a detection according to the first threshold and non-detection takes place according to the second threshold has found. 7. The method according to claim 1 or 2, characterized in that k = 3 and that every part of a pulse packet N + P pulses contains. 8. The method according to any one of claims 1 or 2 or 7, characterized in that the transmitter side, the pulses of the first pulse packet part are such that the phase term is the same where m is an integer predetermined number and n varies between 0 and N + P - 1 such that the pulses of the second part of the pulse packet are such that the phase term is 1 and n between N + P and 2 (N + P ) -1 varies, and that the pulses of the third pulse packet part are such that the phase term is the same where n varies from 2 (N + P) to 3 (N + P) - 1. 9. The method according to any one of claims 1, 2, 7 or 8, characterized in that a Doppler processing is applied on the receiving side to the N pulses, which follow the P pulses for each part of the pulse packet to the Doppler frequency f _{D of} the target with the To determine atomic number p and the apparent frequencies f ' _DA and f _DA , where f' _DA = f ' _DA = f _D and f _DA = f _D , that for each atomic number the amount of signals is calculated, which by the Doppler processing is obtained, and that for each atomic number a shift in the amount of the signal of the first part and the third part is made, which is the same or the same, and then the acquisition decision criteria are applied for each atomic number. 10. The method according to any one of claims 1, 2, 7 to 9, characterized characterized in that the acquisition decision on the receiving side Application criteria for each atomic number are that one on the one hand a sum formation and on the other hand a difference formation between the amount of the Doppler processing signal is made for the three pulse packet parts and a ver equal to the sum signal obtained with a first agreed threshold and a comparison of the received Differential signal with a second predetermined threshold value to be performed, taking the criterion for extraction or confirmation of a target of atomic number p if a detection after the first threshold and a non-detection took place after the second threshold has that. 11. The method according to any one of claims 1 to 10, characterized characterized that the Doppler processing consists in that digital Doppler filtering is carried out. 12. The method according to any one of claims 1 to 11, characterized characterized in that the number Q is equal to the number of processing pulses N is. 13. An apparatus for performing the method according to one of claims 1 to 11, characterized in that a transmitter is provided which has a video signal generator ( 2 ), followed by a phase rotation operator ( 3 ) for performing complex phase rotations, which makes it possible to make the desired phase rotation for each pulse and which is followed by a conversion and amplifier circuit ( 4 ). 14. The apparatus according to claim 13, characterized in that the transmitter for delivering N + P first pulses with a constant phase and N + P further pulses with the same phase is trained. 15. The apparatus according to claim 13, characterized in that the transmitter is designed to deliver such pulse packets that the pulses are delivered in pairs, the first pulse having an original phase, which is the same is. 16. The apparatus according to claim 15, characterized in that the transmitter for emitting signals x (t) and y (t) from two such successive pulses in the baseband that they are pseudo are orthogonal. 17. Device for carrying out the method according to one of claims 1 to 12, characterized in that a receiver is provided which has a module ( 10 ) for eliminating the distance ambiguity, which comprises a phase rotation operator ( 11 ) for introducing complex phase rotations, which is followed by a Doppler processing circuit ( 12 ), the circuits ( 13 ) for eliminating the distance ambiguity for the atomic number p. 18. The apparatus according to claim 17, characterized in that the Doppler processing circuit ( 12 ) Q digital Doppler filter ( 15, 16, 26 ). 19. The apparatus of claim 17 or 18, characterized in that each circuit ( 13 ) for eliminating the distance ambiguity comprises a translation circuit ( 19 ), followed by an extraction circuit ( 14 ). 20. Device according to one of claims 17 to 19, characterized in that the translation circuit (19) includes at least a converter (19, 29, 30). 21. Device according to one of claims 17 to 20, characterized in that the extraction circuit ( 14 ) comprises at least one module which comprises an adder ( 20, 40 ) and a subtractor ( 21, 41 ), each of which has a comparator ( 22nd , 23 and 42, 43 ) respectively, one of the comparators ( 23, 43 ) being followed by an inverter ( 24, 44 ), while the other comparator ( 22, 42 ) and the inverter ( 24, 44 ) is followed by an AND Gate circuit ( 25, 45 ) follows. 22. The apparatus according to claim 21, characterized in that the extraction circuit ( 14 ) comprises two circuit modules ( 20 to 25 or 40 to 45 ) and that an OR gate circuit ( 50 ) follows the AND gate circuits ( 25, 45 ). 23. The device according to any one of claims 17 to 22, characterized characterized that he has as many circuits for rectification the distance ambiguity as ordinal numbers p can occur (p = 0, 1... P-1).