A method, system and device for improving antenna isolation

Abstract

The present invention discloses a method, system and device for improving antenna isolation, the method comprising: obtaining a radar intermediate frequency transmission pulse signal; cutting the obtained pulse signal into N sub-pulses according to a preset slice pulse width and period, and transmitting the sub-pulses; receiving sub-pulse echo signals, collecting sub-pulse echo data according to wave gates; splicing the data collected in the N wave gates; and outputting an echo pulse signal according to the spliced ​​pulse. The present invention can improve antenna isolation in a darkroom close-range radiation test and achieve complete recovery of the echo signal.

Description

Technical Field

[0001] The invention relates to a method, system and device for improving antenna isolation, and belongs to the technical field of communications. Background Art

[0002] In the radiation-based semi-physical simulation, since the propagation distance corresponding to the duration of the radar pulse is much larger than the size of the indoor microwave darkroom, the target echo will return to the receiving antenna before the pulse signal is completely radiated, causing the transmit and receive signals to couple with each other and making it difficult to separate. There are currently two methods to improve isolation: RF cancellation and slicing modulation. The RF cancellation method has a cancellation effect of 30dB to 40dB in a darkroom. The isolation after cancellation does not meet the use requirements, and the signal amplitude jitter after cancellation is large, which does not meet the conditions for further intermediate frequency cancellation. The slicing modulation method currently being studied more is the lossy slicing method, which has high computational requirements and there is a certain amount of information loss in the recovery. Summary of the invention

[0003] The purpose of the present invention is to overcome the deficiencies in the prior art and provide a method, system and device for improving antenna isolation, which can improve antenna isolation in a close-range radiation test in a darkroom and achieve complete recovery of the echo signal. To achieve the above purpose, the present invention is implemented by adopting the following technical solutions:

[0004] In a first aspect, the present invention provides a method for improving antenna isolation, comprising:

[0005] Obtain radar intermediate frequency transmission pulse signal;

[0006] The acquired pulse signal is cut into N sub-pulses according to the preset slice pulse width and period, and the sub-pulses are emitted;

[0007] receiving a sub-pulse echo signal, and collecting data of the sub-pulse echo according to a wave gate;

[0008] Connect and splice the data collected in N wave gates;

[0009] Output an echo pulse signal according to the spliced ​​pulses.

[0010] In combination with the first aspect, further, the radar intermediate frequency transmission pulse signal includes: a radar intermediate frequency transmission pulse signal received by a transmission channel simulation unit, or a radar intermediate frequency transmission pulse signal directly generated by a transmission channel simulation unit.

[0011] In combination with the first aspect, further, the time T of receiving the echo signal of the sub-pulse is:

[0012] T=T0+N*T1 (1)

[0013] In formula (1), T0 represents the time when the sub-pulse reception starts, N represents N sub-pulses, and T1 represents a preset slicing period.

[0014] In combination with the first aspect, further, the gate used to collect sub-pulse echo data satisfies: the gate width can trap the sub-pulse echo and does not obtain a leakage signal, the gate width is twice the sub-pulse width, and the gate starting position t = T0 + (n-1) * T1, (n = 1, 2, ... N), where T0 represents the time to start receiving the sub-pulse, N represents N sub-pulses, and T1 represents a pre-set slicing period.

[0015] In combination with the first aspect, further, the connection and splicing is: taking the starting data in the first wave gate as a reference, the data in the subsequent wave gates are delayed by (n-1)*τ1 relative to the reference, (n=1, 2, ...N) and then superimposed, wherein τ1 represents a pre-set slice pulse width.

[0016] In combination with the first aspect, further, the preset slice pulse width satisfies:

[0017] τ1<L*2 / (3*10 ^8 )(2)

[0018] In formula (2), τ1 represents the preset slice pulse width; L represents the distance from the transmitting antenna to the target in the quiet zone, which satisfies the condition that when the leading edge of the sub-pulse echo reaches the receiving antenna, the trailing edge of the sub-pulse has completed the transmission and has left the transmitting antenna. Otherwise, the received echo pulse signal will overlap with the leakage signal and cannot be separated in the time domain.

[0019] In combination with the first aspect, further, the preset slicing period is more than 3 times of the preset slicing pulse width to ensure that the next sub-pulse is transmitted after one sub-pulse is transmitted and received.

[0020] In a second aspect, the present invention provides a system for improving antenna isolation, comprising:

[0021] Acquisition module: used to acquire radar intermediate frequency transmission pulse signal;

[0022] Slicing module: used to slice the acquired pulse signal into N sub-pulses according to the preset slice pulse width and period, and transmit the sub-pulses;

[0023] Receiving and collecting module: used to receive sub-pulse echo signals and collect sub-pulse echo data according to the wave gate;

[0024] Splicing module: used to connect and splice the data collected in N wave gates;

[0025] Output module: used to output echo pulse signals according to the spliced ​​pulses.

[0026] In a third aspect, the present invention provides an apparatus for improving antenna isolation, comprising a DRFM, wherein the DRFM comprises the system for improving antenna isolation as described in the second aspect, and is used to execute the method for improving antenna isolation as described in the first aspect.

[0027] Compared with the prior art, the method, system and device for improving antenna isolation provided by the embodiments of the present invention have the following beneficial effects:

[0028] The present invention obtains a radar intermediate frequency transmission pulse signal; cuts the obtained pulse signal into N sub-pulses according to a preset slice pulse width and period, and transmits the sub-pulses; the slicing method is relatively lossy slicing method, can retain all information in the echo pulse, is applicable to equal carrier frequency signals, linear frequency modulation signals, nonlinear frequency modulation signals, phase coded signals, and has no special restrictions on signal styles;

[0029] The present invention receives sub-pulse echo signals, collects sub-pulse echo data according to wave gates; connects and splices the data collected in N wave gates; outputs echo pulse signals according to the spliced ​​pulses; and can ensure that the phases of the sub-pulses are continuous after splicing, and the quality of the echo signals after splicing is lossless;

[0030] The present invention can improve antenna isolation in a close-range radiation test in a darkroom and achieve complete recovery of echo signals. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 is a flow chart of a method for improving antenna isolation provided by Embodiment 1 of the present invention;

[0032] Figure 2 It is a schematic diagram of slicing and connecting and splicing an original pulse signal into three sub-pulses in a method for improving antenna isolation provided by Embodiment 2 of the present invention;

[0033] Figure 3 It is an oscilloscope screenshot of the original transmission signal in a method for improving antenna isolation provided in Embodiment 3 of the present invention;

[0034] Figure 4 This is an oscilloscope screenshot of the sub-pulse echo (modulating 4 point targets) after slicing in a method for improving antenna isolation provided in Example 3 of the present invention;

[0035] Figure 5 It is an oscilloscope screenshot of the time domain and frequency domain of the signal after the splicing in the method for improving antenna isolation provided by Embodiment 3 of the present invention;

[0036] Figure 6It is a pulse compression result of collecting sub-pulse echo data after sub-pulse connection and splicing in a method for improving antenna isolation provided by embodiment 3 of the present invention;

[0037] Figure 7 It is the pulse compression result of the original signal echo data in the method for improving antenna isolation provided by Example 3 of the present invention. DETAILED DESCRIPTION

[0038] The present invention will be further described below in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and cannot be used to limit the protection scope of the present invention.

[0039] Embodiment 1:

[0040] like Figure 1 As shown, a method for improving antenna isolation includes:

[0041] Step 1: Get the radar intermediate frequency transmit pulse signal.

[0042] Specifically, the radar intermediate frequency transmission pulse signal includes: a radar intermediate frequency transmission pulse signal received by a transmission channel simulation unit, or a radar intermediate frequency transmission pulse signal directly generated by the transmission channel simulation unit.

[0043] Step 2: Cut the acquired pulse signal into N sub-pulses according to the preset slice pulse width τ1 and period T1, and emit the sub-pulses.

[0044] The pulse width after slicing takes into account the minimum effective distance, that is, the distance between the transmitting antenna and the target in the quiet zone. The pre-set slice pulse width satisfies:

[0045] τ1<L*2 / (3*10 ^8 )(1)

[0046] In formula (1), τ1 represents the preset slice pulse width; L represents the distance from the transmitting antenna to the target in the quiet zone, which satisfies the condition that when the leading edge of the sub-pulse echo reaches the receiving antenna, the trailing edge of the sub-pulse has completed the transmission and has left the transmitting antenna. Otherwise, the received echo pulse signal will overlap with the leakage signal and cannot be separated in the time domain.

[0047] The period after slicing is considered to be that the next sub-pulse should not be radiated from the transmitting antenna before the previous sub-pulse is received by the receiving antenna, so as to achieve a one-to-one correspondence between sub-pulse transmission and reception, which is consistent with the real radar, and the next sub-pulse is transmitted after one sub-pulse is transmitted and received. Then the sub-pulse period is at least twice the sub-pulse width. Considering the broadening of the multi-target echo sub-pulse, the opening of the range window, and a certain protection time, the sub-pulse period is more than 3 times the sub-pulse width.

[0048] Step 3: Receive the sub-pulse echo signal and collect the sub-pulse echo data according to the wave gate.

[0049] Sampling starts from time T0, and the sampling time is from T0 to the end of the last sub-pulse echo. The time T of receiving the sub-pulse echo signal is:

[0050] T=T0+N*T1 (2)

[0051] In formula (2), T0 represents the time when the sub-pulse reception starts, N represents N sub-pulses, and T1 represents a preset slicing period.

[0052] It should be noted that the gate used to collect sub-pulse echo data satisfies: the gate width can trap the sub-pulse echo and does not obtain leakage signals, the gate width is twice the sub-pulse width, and the gate start time is:

[0053] t=T0+(n-1)*T1, (n=1, 2,...N) (3)

[0054] In formula (3), T0 represents the time when the sub-pulse reception starts, N represents N sub-pulses, and T1 represents a preset slicing period.

[0055] Step 4: Connect and splice the data collected in N wave gates.

[0056] Taking the starting data in the first wave gate as a reference, the data in the subsequent wave gates are delayed by (n-1)*τ1 (n=1, 2, ...N) relative to the reference and then superimposed, wherein τ1 represents a preset slice pulse width.

[0057] Step 5: Output an echo pulse signal based on the spliced ​​pulses.

[0058] Embodiment 2:

[0059] Based on the method for improving antenna isolation described in Example 1, an embodiment of cutting an original pulse signal into slices of three sub-pulses and adopting concatenated splicing is provided.

[0060] like Figure 2 As shown, the pulse width of the original pulse signal is τ, and the pulse period of the original pulse signal is T; the pulse width of the sub-pulse after slicing is τ1, and the pulse period of the sub-pulse after slicing is T1; the pulse width of the echo sub-pulse is τ2.

[0061] About pulse width before slicing and after splicing:

[0062] 1) Due to the distribution of target scattering points, the echo signal should be widened by Δτ, and the echo width should be: τ+Δτ;

[0063] 2) After being cut into N pieces, each sub-pulse has a width of τ1, so the pulse width of the original pulse signal τ=N*τ1;

[0064] 3) The echo width of each sub-pulse is τ2. Each sub-pulse is the same as the original wide pulse, and is widened by Δτ. Then: τ2-τ1=Δτ;

[0065] 4) Using the splicing method, the data collected in the next sub-pulse gate is delayed by τ1 relative to the data collected in the previous sub-pulse gate, and the echo front edge of the next sub-pulse is delayed by τ1 relative to the echo front edge of the previous sub-pulse. The overlapped part of the previous sub-pulse and the next sub-pulse is τ2-τ1. After the N sub-pulses are spliced, they are connected by N-1 τ2-τ1. Then the synthesized echo pulse width is:

[0066] N*τ2-(N-1)*(τ2-τ1)=τ+N*Δτ-(N-1)*Δτ=τ+Δτ

[0067] This indicates that the splicing method is used, and the pulse width after splicing is consistent with the original pulse echo width.

[0068] About the phase continuous phase:

[0069] 1) For a single point target or a single scattering point, the leading edge of each sub-pulse is phase-continuous with the trailing edge of the previous sub-pulse during slicing. The intra-pulse characteristics of the point target or single scattering point echo sub-pulse signal are the same as the transmitted sub-pulse signal. The influence of the Doppler effect is not considered, the echo sub-pulse signal will not be broadened, and the leading edge of each sub-pulse echo is phase-continuous with the trailing edge of the previous sub-pulse echo.

[0070] 2) For multiple point targets or multiple scattering point targets, the echo signal is equivalent to the superposition of multiple point targets or multiple scattering point echoes. The same analysis as above shows that the phase of each point target or scattering point sub-pulse echo is continuous after splicing. The phase of multiple point targets or scattering point echoes is equivalent to independent splicing and then superposition, and the phase is also continuous;

[0071] 3) Doppler effect: In a dark room, the target moves at a speed of 1m / s on the moving mechanism, and the corresponding maximum Doppler frequency shift is: 2v / c*f0=80Hz@12GHz. The Doppler effect has a negligible effect on the pulse phase of a sub-pulse with a pulse width of no more than 0.5us, affecting only 0.0144°, which can be ignored.

[0072] 4) This embodiment adopts full-process acquisition to ensure that the phases of the leading and trailing edges of the collected echo sub-pulses are not affected by the acquisition process. The digital wave gate is used to obtain signal data to ensure phase continuity after the sub-pulses are spliced.

[0073] Embodiment 3:

[0074] Based on the method for improving antenna isolation described in Example 1, this embodiment slices a wide pulse linear frequency modulation signal and splices and restores the echo.

[0075] The original width pulse linear frequency modulation signal parameters are as follows: intermediate frequency center frequency f I =750MHz; pulse width τ=4.16μs; period T=104.160μs; signal bandwidth B=400MHz.

[0076] The simulated signal irradiates 4 targets, the amplitude ratios of the four targets are 6:2:1:4, and the intervals are 3.2m, 4m and 2.4m respectively.

[0077] The slice pulse width and slice period used are as follows: slice pulse width τ1 = 277.33 ns; slice period T1 = 805.33 ns.

[0078] like Figure 3-5 As shown in the figure, the pulse width of the original transmission signal is 4160ns, and the pulse width of the spliced ​​signal is 4224ns. The complete pulse after the sliced ​​sub-pulses are spliced ​​is 64ns longer than the original transmission signal. The theoretical value is (3.2m+4m+2.4m)*2 / (3*10 ^8 )m / s=64ns, the actual expansion value is consistent with the theoretical value.

[0079] like Figure 6-7 As shown, after the slice sub-pulses are spliced ​​and pulse compressed, the target spacing and amplitude are consistent with the original signal echo pulse compression results. The four target spacings are 3.2m, 4m and 2.4m, and the four target amplitude differences are 15.56dB, 6dB, 0dB and 12dB.

[0080] The lossless slicing modulation isolation method can realize time-sharing of transmission and reception, completely solving the isolation problem. At the same time, the echo sub-pulses are connected and spliced, and the spliced ​​echo is completely equivalent to the echo without slicing.

[0081] Embodiment 4:

[0082] This embodiment provides a system for improving antenna isolation, including:

[0083] Acquisition module: used to acquire radar intermediate frequency transmission pulse signal;

[0084] Slicing module: used to slice the acquired pulse signal into N sub-pulses according to the preset slice pulse width and period, and transmit the sub-pulses;

[0085] Receiving and collecting module: used to receive sub-pulse echo signals and collect sub-pulse echo data according to the wave gate;

[0086] Splicing module: used to connect and splice the data collected in N wave gates;

[0087] Output module: used to output echo pulse signals according to the spliced ​​pulses.

[0088] Embodiment 5:

[0089] This embodiment provides a device for improving antenna isolation, including a DRFM. The DRFM includes the system for improving antenna isolation described in Embodiment 4, and is used to execute the method for improving antenna isolation described in Embodiment 1.

[0090] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for improving antenna isolation, characterized in that: include: Acquire a radar intermediate frequency transmission pulse signal; wherein the radar intermediate frequency transmission pulse signal includes: a radar intermediate frequency transmission pulse signal received by a transmission channel simulation unit, or a radar intermediate frequency transmission pulse signal directly generated by the transmission channel simulation unit; The acquired pulse signal is cut into N sub-pulses according to the preset slice pulse width and period, and the sub-pulses are emitted; Among them, the preset slice pulse width satisfies: τ1<L*2 / (3*10 ^8 ) (2) In formula (2), τ1 represents the preset slice pulse width; L represents the distance from the transmitting antenna to the target in the quiet zone, which satisfies the condition that when the leading edge of the sub-pulse echo reaches the receiving antenna, the trailing edge of the sub-pulse has completed the transmission and has left the transmitting antenna. Otherwise, the received echo pulse signal will overlap with the leakage signal and cannot be separated in the time domain. The preset slicing period is more than three times of the preset slicing pulse width, so as to ensure that the next sub-pulse is transmitted after one sub-pulse is transmitted and received; Receive the sub-pulse echo signal, and collect the sub-pulse echo data according to the wave gate; wherein the wave gate used to collect the sub-pulse echo data satisfies: the wave gate width can trap the sub-pulse echo and does not obtain the leakage signal, the wave gate width is twice the sub-pulse width, and the wave gate starting position t=T0+(n-1)*T1, wherein T0 represents the time when the sub-pulse is started to be received, N represents N sub-pulses, T1 represents a preset slice period, and n=1, 2, ...N; The data collected in N wave gates are connected and spliced; the connection and splicing is: taking the starting data in the first wave gate as the reference, the data in the subsequent wave gates are delayed by (n-1)*τ1 relative to the reference and then superimposed, wherein τ1 represents the preset slice pulse width, N represents N sub-pulses, and n=1, 2, ...N; Output echo pulse signal according to the spliced ​​pulse Among them, about the pulse width before slicing and after splicing: 1) Due to the distribution of target scattering points, the echo signal should be widened by Δτ, and the echo width should be: τ+Δτ; 2) After being cut into N pieces, each sub-pulse has a width of τ1, so the pulse width of the original pulse signal τ=N*τ1; 3) The echo width of each sub-pulse is τ2. Each sub-pulse is the same as the original wide pulse, and is widened by Δτ. Then: τ2-τ1=Δτ; 4) Using the splicing method, the data collected in the next sub-pulse gate is delayed by τ1 relative to the data collected in the previous sub-pulse gate, and the echo front edge of the next sub-pulse is delayed by τ1 relative to the echo front edge of the previous sub-pulse. The overlapped part of the previous sub-pulse and the next sub-pulse is τ2-τ1. After the N sub-pulses are spliced, they are connected by N-1 τ2-τ1. Then the synthesized echo pulse width is: N*τ2-(N-1)*(τ2-τ1)=τ+N*Δτ-(N-1)*Δτ=τ+Δτ This indicates that the splicing method is used, and the pulse width after splicing is consistent with the original pulse echo width.

2. The method for improving antenna isolation according to claim 1, characterized in that: The time T of receiving the echo signal of the sub-pulse is: T=T0+N*T1 (1) In formula (1), T0 represents the time when the sub-pulse reception starts, N represents N sub-pulses, and T1 represents a preset slicing period.

3. A system for improving antenna isolation, characterized in that: include: Acquisition module: used to acquire radar intermediate frequency transmission pulse signal; wherein, the radar intermediate frequency transmission pulse signal includes: radar intermediate frequency transmission pulse signal received by the transmission channel simulation unit, or radar intermediate frequency transmission pulse signal directly generated by the transmission channel simulation unit; Slicing module: used to slice the acquired pulse signal into N sub-pulses according to the preset slice pulse width and period, and transmit the sub-pulses; Among them, the preset slice pulse width satisfies: τ1<L*2 / (3*10 ^8 ) (2) In formula (2), τ1 represents the preset slice pulse width; L represents the distance from the transmitting antenna to the target in the quiet zone, which satisfies the condition that when the leading edge of the sub-pulse echo reaches the receiving antenna, the trailing edge of the sub-pulse has completed the transmission and has left the transmitting antenna. Otherwise, the received echo pulse signal will overlap with the leakage signal and cannot be separated in the time domain. The preset slicing period is more than three times of the preset slicing pulse width, so as to ensure that the next sub-pulse is transmitted after one sub-pulse is transmitted and received; Receiving and acquisition module: used to receive sub-pulse echo signals and acquire data of sub-pulse echoes according to a wave gate; wherein the wave gate used to acquire sub-pulse echo data satisfies: the wave gate width can trap the sub-pulse echo and does not acquire leakage signals, the wave gate width is twice the sub-pulse width, and the wave gate starting position t=T0+(n-1)*T1, wherein T0 represents the time when sub-pulse reception starts, N represents N sub-pulses, T1 represents a preset slice period, and n=1, 2, ...N; Splicing module: used to connect and splice the data collected in N wave gates; the connection and splicing is: taking the starting data in the first wave gate as the reference, the data in the subsequent wave gates are delayed by (n-1)*τ1 relative to the reference, and then superimposed, wherein τ1 represents the preset slice pulse width, N represents N sub-pulses, and n=1, 2, ...N; Output module: used to output echo pulse signals according to the spliced ​​pulses; Among them, about the pulse width before slicing and after splicing: 1) Due to the distribution of target scattering points, the echo signal should be widened by Δτ, and the echo width should be: τ+Δτ; 2) After being cut into N pieces, each sub-pulse has a width of τ1, so the pulse width of the original pulse signal τ=N*τ1; 3) The echo width of each sub-pulse is τ2. Each sub-pulse is the same as the original wide pulse, and is widened by Δτ. Then: τ2-τ1=Δτ; 4) Using the splicing method, the data collected in the next sub-pulse gate is delayed by τ1 relative to the data collected in the previous sub-pulse gate, and the echo front edge of the next sub-pulse is delayed by τ1 relative to the echo front edge of the previous sub-pulse. The overlapped part of the previous sub-pulse and the next sub-pulse is τ2-τ1. After the N sub-pulses are spliced, they are connected by N-1 τ2-τ1. Then the synthesized echo pulse width is: N*τ2-(N-1)*(τ2-τ1)=τ+N*Δτ-(N-1)*Δτ=τ+Δτ This indicates that the splicing method is used, and the pulse width after splicing is consistent with the original pulse echo width.

4. A device for improving antenna isolation, characterized in that: The DRFM comprises the system for improving antenna isolation as claimed in claim 3, and is used to execute the method for improving antenna isolation as claimed in claims 1-2.

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