U.S. patent application number 14/192066 was filed with the patent office on 2015-04-02 for radar proximity fuse and processing method of an echo radar signal for the acquisition of distance information between a target and a doppler radar.
The applicant listed for this patent is MBDA ITALIA S.p.A.. Invention is credited to Riccardo Carradori, Carlo Conti, Massimo Guerrera, Andrea Izzi, Fausto Petrullo.
Application Number | 20150091748 14/192066 |
Document ID | / |
Family ID | 48485342 |
Filed Date | 2015-04-02 |
United States Patent
Application |
20150091748 |
Kind Code |
A1 |
Conti; Carlo ; et
al. |
April 2, 2015 |
RADAR PROXIMITY FUSE AND PROCESSING METHOD OF AN ECHO RADAR SIGNAL
FOR THE ACQUISITION OF DISTANCE INFORMATION BETWEEN A TARGET AND A
DOPPLER RADAR
Abstract
Radar proximity fuse (1) adapted to receive an echo radar signal
(s_rx) produced by the reflection on a target (T) of a transmitted
radar signal (s_tx), the transmitted signal (s_tx) comprising a
sequence of M impulses coded with a phase code (p_cd). The radar
proximity fuse (1) comprising: a radiofrequency analog receiving
front end (15) for receiving the echo radar signal (s_rx), adapted
to provide in output a baseband signal starting from the echo radar
signal (s_rx) received; an analog to digital converter (12)
positioned at the output of the analog receiving front end (15)
adapted to sample the baseband signal to obtain in output a
sequence of digital samples (d_rx); a digital processing block (20)
comprising a plurality of digital processing channels (C1, C2, . .
. CN) each associated to a respective range gate and each adapted
to receive in input said sequence of digital samples (d_rx).
Inventors: |
Conti; Carlo; (Rome, IT)
; Petrullo; Fausto; (Rome, IT) ; Guerrera;
Massimo; (Rome, IT) ; Izzi; Andrea; (Rome,
IT) ; Carradori; Riccardo; (Rome, IT) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
MBDA ITALIA S.p.A. |
Rome |
|
IT |
|
|
Family ID: |
48485342 |
Appl. No.: |
14/192066 |
Filed: |
February 27, 2014 |
Current U.S.
Class: |
342/68 |
Current CPC
Class: |
G01S 13/26 20130101;
F42C 13/042 20130101 |
Class at
Publication: |
342/68 |
International
Class: |
F42C 13/04 20060101
F42C013/04 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 28, 2013 |
IT |
RM2013A000120 |
Claims
1. Radar proximity fuse (1) adapted for receiving a radar echo
signal (s_rx) produced by the reflection on a target (T) of a
transmitted radar signal (s_tx), the transmitted signal (s_tx)
comprising a sequence of M pulses coded with a phase code (p_cd),
the radar proximity fuse (1) comprising: a phase code generator (4)
adapted to provide said phase code (p_cd); a radiofrequency analog
receiving front end (15) for receiving the radar echo signal
(s_rx), adapted to provide in output a baseband signal starting
from the received radar echo signal (s_rx); an analog to digital
converter (12) placed at the output of the analog receiving front
end (15) adapted for sampling the baseband signal to obtain in
output a sequence of digital samples (d_rx); a digital processing
block (20) comprising a plurality of digital processing channels
(C1, C2, . . . CN) configured to operate in parallel and each
associated to a respective observation distance and each adapted
for receiving in input said sequence of digital samples (d_rx);
wherein each digital processing channel (C1, C2, . . . CN)
comprises: a delay block (21) adapted for producing a replica of
the phase code (p_cd) delayed with a respective time delay (d1, . .
. , dN) corresponding to a respective observation distance between
the fuse (1) and the target (T); a digital multiplier (22) adapted
for multiplying the sequence of digital samples with digital
samples of said delayed replica to produce in output a phase
decoded sequence of digital samples; a digital information
extraction block (23) adapted for processing the phase decoded
sequence of digital samples to extract information correlated to
the distance between the target (T) and the digital fuse (1).
2. Radar proximity fuse (1) according to claim 1, wherein the phase
code (p_cd) is dynamically programmable during the operation of
said fuse (1).
3. Radar proximity fuse (1) according to claim 1, wherein said
respective time delay (d1, . . . , dN) is dynamically programmable
during the operation of said fuse (1).
4. Radar proximity fuse (1) according to claim 1, wherein each
digital processing channel (C1, . . . CN) comprises an extraction
block of distance information (23) comprising a sum block (30)
configured to obtain in output a sequence of samples in which each
sample is obtained, by means of a digital evaluation operation of a
moving sum or a moving average, from a number K of samples of the
respective phase decoded sequence of digital samples, in which K is
an integer which represents the number of samples acquired by the
analog to digital converter (12) for said sequence of M pulses of
the radar echo signal (s_rx).
5. Radar proximity fuse (1) according to claim 4, in which in the Z
transform domain the sum block (30) is configured as a cascade
between a perfect integrator and a mobile observation window of
length equal to K samples.
6. Radar proximity fuse (1) according to claim 5, wherein said
distance information extraction block (23) comprises a band
reduction digital block (31) at the output of the sum block
(30).
7. Radar proximity fuse (1) according to claim 6, wherein the band
reduction block (27) comprises a sum and re-sampling block (32)
configured to obtain, by means of an evaluation operation of a sum
or an average, an output sample starting from each disjoint group
of J* consecutive samples of the sequence of digital samples
obtained in output from the sum block (30), in which J* is an
integer representing a band reduction factor.
8. Radar proximity fuse (1) according to claim 6, wherein the band
reduction block (27) comprises at the output of the sum and
re-sampling block (32) a low pass digital filter (33) and at the
output of said low pass digital filter (33) a re-sampling block
(34) to take into account of the band restriction performed by the
low pass digital filter (33).
9. Radar proximity fuse (1) according to claim 1, wherein said
baseband signal has a bandwidth of the useful signal of the order
of hundreds of MHz.
10. Radar proximity fuse (1) according to claim 1, wherein said
transmitted radar signal is a signal in the Ku band.
11. Radar proximity fuse (1) according to claim 1, wherein said
digital processing block (20) is adapted to directly receive in
input the phase code (p_cd) produced in output by the code
generator (4).
12. Radar proximity fuse (1) according to claim 1, in which the
radio frequency analog receiving front end (15) is a single channel
and single-output front end, the analog to digital converter (12)
is adapted to only sample amplitudes of the baseband analog signal
produced in output by the radio frequency analog receiving front
end (15) for providing as output digital samples representative of
said amplitudes.
13. Radar proximity fuse (1) according to claim 1, wherein said
analog to digital converter is a multi-bit converter.
14. Missile or rocket or weapon comprising a radar proximity fuse
(1) according to claim 1.
15. Processing method of a radar echo signal for the acquisition of
distance information between a target (T) and a Doppler radar,
comprising the steps of: receiving a radar echo signal (s_rx)
produced by the reflection on a target (T) of a transmitted radar
signal (s_tx), the transmitted radar signal (s_tx) comprising
pulses coded with a phase code (p_cd) provided by a phase code
generator (4): processing the radar echo signal (s_rx) in the
analog domain to obtain a baseband analog signal; sampling the
baseband analog signal to obtain in output a sequence of digital
samples (d_rx); performing a parallel digital processing on several
channels of said sequence of digital samples (d_rx), each channel
being associated to a respective observation distance; wherein said
digital processing comprises for each channel the steps of:
producing a replica of the phase code (p_cd) delayed by a
respective time delay corresponding to a respective observation
distance between said fuse (1) and said target (T); multiplying
said sequence of digital samples with said delayed replica to
produce in output a phase decoded sequence of digital samples;
processing the phase decoded sequence of digital samples to extract
information correlated to the distance between the target (T) and
the digital fuse (1).
Description
[0001] The present description refers to the technical field of
Doppler radar systems and relates in particular to a processing
method of an echo radar signal for the acquisition of distance
information between a target and a Doppler radar.
[0002] Radar proximity fuses have been known of in the prior art
for a long time, for example of the type used on board a missile,
used to estimate the distance between the missile and a target so
as to trigger the detonation of a warhead transported by a missile
once it has been found that the distance between the missile and a
target is less than a predetermined distance.
[0003] One example of a radar proximity fuse belonging to the prior
art is disclosed in U.S. Pat. No. 4,297,702. Said proximity fuse
comprises a transmission chain of a radar signal with phase-coded
pulses and a chain for receiving and processing the echo radar
signal. The chain for receiving and processing the echo radar
signal, comparing the echo radar signal with a plurality of delayed
replicas of the transmitted signal, makes it possible to perform an
observation over a plurality of range gates thanks to the provision
of a plurality of parallel analog processing paths of the echo
radar signal received. In the aforementioned US patent the
possibility of observing the echo radar signal with respect to a
plurality of range gates is achieved at the high price of
introducing a structural complication due to the analog components
provided for on the parallel analog processing paths of the
signal.
[0004] Another example of a radar proximity fuse belonging to the
prior art is disclosed in US patent application published at No.
2001/0024170 A1. Said radar proximity fuse is relatively complex
from the hardware point of view since down-conversion and I&Q
sampling and processing of both the transmitted and the return
radiofrequency signals is required. The object of the present
disclosure is therefore to make available a radar proximity fuse
which makes it possible to overcome the drawbacks mentioned above
with reference to the prior art.
[0005] Such object is achieved by a radar proximity fuse as defined
in general in claim 1. Preferred or advantageous embodiments of the
aforesaid proximity fuse are defined in the appended dependent
claims.
[0006] The present invention also relates to a processing method of
an echo radar signal for the acquisition of distance information
between a target and a Doppler radar.
[0007] The invention will be better understood from the detailed
description given below, by way of a non-limiting example, of a
specific embodiment, with reference to the appended drawings,
wherein:
[0008] FIG. 1 shows a functional block diagram of a radar proximity
fuse comprising a digital signal processor;
[0009] FIG. 2 shows a functional block diagram of the digital
signal processor in FIG. 1, comprising a plurality of delay blocks
and a plurality of extraction blocks of distance information
between the proximity fuse and a target; and
[0010] FIG. 3 shows a functional diagram of an extraction block of
distance information between the proximity fuse and the target.
[0011] In the drawings, elements which are the same or similar will
be indicated using the same reference numerals.
[0012] FIG. 1 schematically shows a non-limiting embodiment of a
proximity fuse 1 of the Doppler radar type. According to a
preferred embodiment, the aforesaid proximity fuse 1 is a CW
(Continuous Wave) Doppler radar proximity fuse in CW.
[0013] The radar proximity fuse 1 is for example destined to be
used on board a missile or rocket or weapon so as to trigger the
detonation of an explosive warhead provided on board said missile
or rocket or weapon. To such purpose, the proximity fuse 1 may be
operatively connected to a detonator (not shown in the
drawings).
[0014] The proximity fuse 1 comprises a local oscillator 2 adapted
to produce in output a radio frequency carrier signal, for example
in Ku band, and a modulator 3 "MOD" adapted to modulate the radio
frequency carrier signal with a phase code p_cd. The phase code
p_cd is configured to provide a response with a peak when compared
with a phase replica of itself and to supply a low amplitude
response in other circumstances. The phase code is provided in
output by a phase code generator 4 "GEN" operatively connected to
the modulator 3. For example, the phase code generator 4 comprises
a memory or register adapted to memorise said phase code p_cd, as
symbols of the code or as digital samples of said symbols.
[0015] For example, without thereby introducing any limitation, the
phase code p_cd is a binary phase code. According to one
embodiment, the aforesaid phase code p_cd is a pseudo random binary
code such that at the output of the modulator 3 a signal is
produced in the form of a sequence of M pulses. Such pulses,
depending on the symbols of the phase code p_cd have, in an
appropriate phase reference system, a 0.degree. phase (for example
in correspondence with a symbol equal to "0") or a 180.degree.
phase (for example in correspondence with a symbol equal to "1"). M
represents an integer, which also corresponds to the length of the
phase code p_cd, preferably greater than one and generally
amounting about to several tens or being of the hundred order.
[0016] According to an advantageous embodiment, the aforesaid phase
code p_cd is adapted to be reconfigured dynamically, in this way it
is possible to choose and/or vary the phase code as needed
depending on the disturbance or to avoid real time recognition by
third parties of said code and its reproduction aimed to
circumventing the proximity fuse 1. To vary the phase code p_cd it
is for example possible to control the generation block 4 before or
even during the mission.
[0017] The proximity fuse 1 preferably comprises a signal amplifier
5 and a transmitter aerial 6 for the remote radio transmission of
the radar signal produced in output by the modulator 3. The
transmitter aerial 6 is for example a system of aerials comprising
at least one pair of aerials.
[0018] The radio signal in output from the transmitter aerial 6
represents the incident radar signal s_tx. Said incident radar
signal s_tx, or transmitted radar signal, presents itself in the
form of a sequence of phase-coded pulses. In the case in which such
incident radar signal s_tx strikes a target T, a reflected signal
is produced which represents an echo radar signal s_rx. As is
known, the echo radar signal includes a useful signal component,
that is to say the signal reflected by the target T and thus
essentially assimilable to a sequence of phase-coded pulses M, and
a noise signal component, essentially represented by unwanted
reflections on the ground, on water, on the vegetation or on
infrastructures.
[0019] The digital fuse 1 comprises a radio frequency analog
receiving front end 15 for receiving the echo radar signal s_rx,
adapted to provide in output a baseband signal starting from the
echo radar signal s_rx received, by means of processing in the
analog domain.
[0020] The radio frequency analog receiving front end 15 comprises
a receiving aerial 8 for receiving the echo radar signal s_rx and
preferably a low noise amplifier 9. The receiving aerial 8 is for
example a system of aerials comprising at least one pair of
aerials. It will be clear to a person skilled in the art that the
same aerial 6 or system of aerials used in transmission may be used
for receiving the echo radar signal s_rx, for example by means of a
circulator.
[0021] According to a particularly advantageous embodiment, the
radio frequency analog receiving front end 15 is a single channel
and single-output front-end. In other words, from the receiving
aerial 8 to the output of the radio frequency analog receiving
front end 15 only one analog processing channel is provided.
[0022] The radio frequency analog receiving front end 15 comprises
a baseband conversion block 10, for example consisting of or
comprising a mixer 10 adapted to receive in input the radio
frequency signal produced in output by the modulator 3, and the
echo radar signal s_rx as caught by the aerial 8 and possibly
amplified by means of the low noise amplifier 9. The baseband
signal in output from the baseband conversion block 10 has, for
example a bandwidth of the useful signal to the order of hundreds
of MHz.
[0023] According to one embodiment, the radio frequency analog
receiving front end 15 further comprises an anti-aliasing analog
filter 11 "AAF" having the function of cutting out the components
of the baseband signal outside the useful signal band and that of
cutting out the unwanted products of intermodulation observable in
output from the mixer 10. The aforesaid analog anti-aliasing filter
11 is a low pass filter or more preferably a band pass filter
adapted to eliminate a possible continuous component of the
baseband signal. For example, the aforesaid band pass filter has a
low cut-off frequency of the order of tens of KHz. Such continuous
component would in fact represent a direct return of the
transmitted signal s_tx in the radio frequency analog receiving
front end 15 and would have pulses having substantially, instant by
instant, the same phase as the pulses of the signal in input to the
mixer 10 as provided in output by the modulator 3.
[0024] The radar proximity fuse 1 further comprises: [0025] an
analog to digital converter 12 "A/D" adapted to convert the analog
signal produced in output by the radio frequency analog receiving
front end 15 into a sequence of digital samples d_rx; [0026] a
digital processing block 20 "D_PROC" adapted to process the
sequence of digital samples d_rx for example to produce in output a
command signal of the detonation fr_c.
[0027] According to a preferred embodiment, the analog to digital
converter 12 is such as to provide in output a number J of samples
for each pulse of the echo radar signal s_rx. J is preferably an
integer greater than one and in a non-limiting manner comprised
between 2 and 10, extremes included.
[0028] Preferably, the analog to digital converter 12 is a
multi-bit analog to digital converter, for example a 12-bit analog
to digital converter.
[0029] According to a non-limiting example, the sampling frequency
of the analog to digital converter is about 250 MHz.
[0030] According to a particularly advantageous embodiment, in
which the radio frequency analog receiving front end 15 is a single
channel and single-output front-end, the analog to digital
converter 12 is adapted to only sample amplitudes of the baseband
analog signal produced in output by the radio frequency analog
receiving front end 15 for providing as output digital samples
representative of said amplitudes. This means that separate analog
to digital converters, for example two separate analog to digital
converters, for sampling the in-phase and quadrature components of
the baseband analog signal (and therefore two separate outputs of
in the radio frequency analog receiving front end 15) are not
provided, but only amplitude sampling is performed. As shown in
FIG. 1, the digital processing block 20 is such as to also receive
in input the phase code p_cd, produced in output by the code
generator 4 and used in the phase coding of the radar signal in
transmission. According to a preferred embodiment, like the one
shown in FIGS. 1 and 2, the digital processing block 20 is adapted
to directly receive in input the phase code p_cd produced in output
by the code generator 4, for example because there is a direct
digital connection between the code generator 4 and the processing
block 20. Non limiting examples of a direct digital connection are:
direct reading by the processor from a memory of the code generator
4 in which the phase code is stored or connection with a digital
bus provided between the code generator and the digital processor.
With reference to FIG. 2, the digital processing block 20 comprises
a plurality of digital processing channels C1,C2, . . . , CN,
wherein N is an integer greater than 1, each associated with a
respective observation distance (range gate). Each of the digital
processing channels C1,C2, . . . , CN, comprises a digital delay
block 21 "DL" adapted to produce delayed replicas of the phase code
p_cd, wherein a time delay d1, d2 . . . , dN is associated with
each delayed replica which depending on the Doppler radar equation
corresponds to a given range gate between the target T and the
digital fuse 1. For example, the aforesaid digital delay blocks 21
are digital delay lines, or delay registers or are fully
implemented via software by means of appropriate management of a
memory area.
[0031] According to one embodiment, the delays d1,d2, . . . , dN
associated with the various digital delay blocks 21 are adjustable
parameters which can be dynamically reconfigured over time, for
example even during operation of the radar proximity fuse 1, that
is to say before or during the mission. Such ability to reconfigure
the delays d1,d2, . . . , dN advantageously makes it possible to
implement one or more of the following advanced functions even in
the presence of hostile environments: contemporarily following
several targets, identifying and isolating the clutter
contribution, performing an altimeter function.
[0032] In output from each digital delay block 21 each digital
processing channel C1, C2, . . . , CN comprises a digital
multiplier 22 adapted to multiply, sample by sample, the delayed
replicas of the phase code with the sequence of digital samples
d_rx produced in output by the digital analog converter 12 so as to
produce in output sequences of phase decoded digital samples. Such
operation is used to cancel the phase code from the sequence of
digital samples. It is to be noted that such cancellation
effectively takes place in the case in which one of the delayed
replicas has the associated delay d1,d2, . . . , dN which
corresponds substantially to the overall flight time of the radar
signal which is equal to the sum of the propagation time of the
radar signal transmitted s_tx between the transmitter aerial 6 and
the target T with the propagation time of the echo radar signal
s_rx between the target T and the receiver aerial 8. It is to be
noted that in the case in which the analog to digital converter 12
is such as to produce in output for each pulse of the echo radar
signal s_rx a number J of samples greater than 1, the samples of
the delayed replicas of the phase code in input to the digital
multipliers 22 are maintained J times for each phase code symbol
p_cd so that the J samples of a same pulse are multiplied by a same
phase code symbol.
[0033] In output from each digital multiplier 22 each digital
processing channel C1, C2, . . . , CN comprises a respective
digital information extraction block 23 "DT" responsible for
extracting information correlated to the distance of the target T
in relation to the digital fuse 1. Such information extraction is
performed by processing the sequence of phase decoded digital
samples as obtained at the output of the digital multipliers
22.
[0034] With reference to FIG. 3, according to one embodiment, each
of the information extraction blocks 23 comprises a sum block 30
configured to supply in output a sequence of samples in which each
sample is obtained, by means of a digital calculation operation of
a moving sum or of a moving media, from a number K of samples of
the respective sequence of phase decoded digital samples, in which
K is an integer which represents the number of samples acquired by
the analog to digital converter 12 for each sequence of M pulses of
the echo radar signal s_rx and is for example of the order of some
hundreds. In other words K=J.times.M.
[0035] A register of K elements managed on a LIFO
(Last-In-First-Out) basis is for example provided to perform the
moving sum of K samples. The addition of a new sample takes place
at an end position of the register making the samples already
memorised move along by one position and determining the
cancellation of the sample memorised at the opposite end, operation
expressed in the domain of the Z-transform as a multiplication by
(1-z.sup.-K), to then sum the K elements of the register, operation
expressed in the domain of the Z-transform as a division by
(1-z.sup.-1). In other words, in the domain of the Z-transform the
sum block 30 is configured as a cascade (that is to say a
multiplication in the domain of the Z-transform) between a perfect
integrator and a mobile observation window having a length equal to
K samples.
[0036] According to one embodiment, each of the information
extraction blocks 23 comprises a band reduction digital block 31 at
the output of the sum block 30. For example, the band reduction
digital block 27 comprises a sum and re-sampling block 32 "D_S-RES"
configured to obtain, by means of a calculation operation of a sum
or of an average, a sample in output starting from each disjoint
group of J* consecutive samples of the respective sequence of
digital samples obtained in output from the sum block 30. The
number J* is an integer which represents the band reduction factor
and is preferably a number much smaller than K and more preferably
equal to the number J of samples acquired in reception (by means of
the analog to digital converter 12--FIG. 1) for each pulse of the
echo radar signal s_rx. It is to be noted that in the case in which
J*=J a sample in output for each pulse of the echo radar signal
s_rx is obtained in output from the sum and re-sampling block
32.
[0037] In practice, the sum and re-sampling block 32 is responsible
for performing a band reduction by a factor J*, merging the
information relative to groups of J* consecutive samples, de facto
performing a re-sampling on the basis of a first re-sampling
frequency.
[0038] This way it is possible to obtain a reduction of the
computational load. For example, the signal in output from the sum
and re-sampling block 32 has a frequency, or rather a re-sampling
frequency, of the order of tens of MHz.
[0039] According to one embodiment, the band reduction block 27
comprises format the output of the sum and re-sampling block 32 a
digital low pas filter 33 "D_LPF", preferably a filter of the FIR
type having a pass band equal to the range of Doppler frequencies
of interest.
[0040] According to one embodiment, the band reduction block 27
comprises at the output of the digital low pass filter 33 a
re-sampling block 34 "D_RES2", adapted to perform a re-sampling of
the signal in output from the digital low pass filter 33 with a
second re-sampling frequency lower than the first re-sampling
frequency of the sum and re-sampling block 32, to take into
consideration the band restriction performed by the digital low
pass filter 33. For example, the second re-sampling frequency is of
the order of a MHz.
[0041] According to one embodiment, each of the information
extraction blocks 23 comprises at the output of the sum block 30 or
at the output of the band reduction block 31 (if provided) a
digital calculation block 33 "FTT" of a Fourier transform of the
FFT type (Fast Fourier Transform) adapted to obtain for each
Doppler frequency of interest a respective amplitude value and a
respective phase value.
[0042] With reference to FIG. 2, the digital processing block 20
comprises a distance evaluation block 25 "EVAL" adapted to receive
in input the amplitude and phase values calculated for each Doppler
frequency of interest by the calculation blocks FFT 35 of the
various processing channels C1, C2, . . . , CN which thus represent
the information correlated to the fuse-target distance extracted by
the digital blocks 23. The evaluation block 25 is configured to
compare the aforementioned amplitudes with one or more predefined
thresholds so as to establish the possible presence of a target at
or near the range gates associated with the processing channels C1,
C2, . . . , CN and to a given Doppler frequency analysed. If the
presence of a target T at a given range gate is established, the
evaluation block 25 is for example such as to send in output a
detonation signal f_rc, for example to a detonator, to cause the
explosion of the head.
[0043] It is to be noted that the above detailed description made
for the digital fuse 1 corresponds to the description of the
processing method of an echo radar signal for the acquisition of
distance information between a target and a Doppler radar,
comprising the steps of: [0044] receiving an echo radar signal s_rx
produced by the reflection on a target T of a transmitted radar
signal s_tx, the transmitted radar signal s_tx comprising pulses
coded with a phase code p_cd: [0045] performing an analog
processing of the echo radar signal s_rx received to produce in
output a baseband signal; [0046] sampling the analog baseband
signal to obtain in output a sequence of digital samples d_rx;
[0047] performing parallel digital processing on several channels
of the sequence of digital samples d_rx, each channel being
associated to a respective range gate.
[0048] It is to be noted that the aforesaid method, as well as
being utilisable in a radar proximity fuse may be used in other
applications in which there is a need to estimate the distance
between reciprocally mobile entities, for example in the abstract
also in anti-collision radar for vehicles, or in vehicle speed
detectors, for example land transport vehicles. It may in addition
be noted that the aforesaid method can in general be implemented in
proximity or distance sensors or in movement parameter sensors,
such as speed sensors.
[0049] In the aforesaid method the step of performing the aforesaid
digital processing on several channels comprises for each channel
the steps of: [0050] producing a replica of the phase code p_cd
delayed by a time delay corresponding to a respective range gate
between the fuse 1 and the target T; [0051] multiplying said
sequence of digital samples with digital samples of the delayed
replica to produce in output a sequence of phase decoded digital
samples; [0052] processing said decoded sequence of digital samples
to extract information correlated to the distance of the target T
in relation to the digital radar fuse 1.
[0053] Further features of the aforesaid method may be directly
deduced from the detailed description made above for the radar
proximity fuse 1 and will therefore not be repeated.
[0054] From the description made above it may be seen how a
proximity radar fuse and a processing method of the type described
above fully achieve the intended objects. In fact, by performing
digital processing on several channels immediately downstream of
the analog receiving front end 15, the above described radar
proximity fuse described above makes it possible to perform an
observation over a plurality of distances and/or a plurality of
targets without limit within the range of the functioning distance
of the Doppler radar and without requiring the presence of
dedicated analog components replicated for each channel. This way,
the radar proximity fuse described above represents a streamlined
solution from the point of view of the complexity of the analog
hardware components required, relatively lightweight and occupying
relatively little space.
[0055] Advantageously, by having available data provided by
parallel digital processing over several channels it is possible to
implement advanced functions such as: contemporarily observing
various targets at different distances; and/or using a channel to
measure the height of flight from the ground, not necessarily to
explode the warhead but to guide a missile at a predefined height
from the ground; and/or dedicating one channel to the clutter echo
(e.g. in vertical mission towards the ground) which will probably
contain a very high signal and dedicating other channels to the
target or to the targets.
[0056] For the reasons already explained in the description above,
the embodiments which provide for the possibility of dynamically
reconfiguring the phase code and/or delays are, in addition,
particularly advantageous.
[0057] Obviously, a person skilled in the art may make numerous
modifications and variations to the radar proximity fuse and
processing method described above so as to satisfy contingent and
specific requirements, while remaining within the sphere of
protection of the invention as defined by the following claims.
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