CN105785325B - A kind of variable period automobile collision avoidance radar frame structure and its design method - Google Patents
A kind of variable period automobile collision avoidance radar frame structure and its design method Download PDFInfo
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- CN105785325B CN105785325B CN201610147143.4A CN201610147143A CN105785325B CN 105785325 B CN105785325 B CN 105785325B CN 201610147143 A CN201610147143 A CN 201610147143A CN 105785325 B CN105785325 B CN 105785325B
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
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Abstract
The present invention discloses a kind of variable period automobile collision avoidance radar transmitting signal frame structure and its design method, the frame structure are specifically divided into four layers using the sampling interval as minimum time unit：First layer, a frame are made of the time slot of multiple equal lengths, and slot length is determined according to number of time slots in frame length and a frame；The second layer, a time slot include the identical sub-slots of multiple length, and sub-slots length is determined according to system transmitting antenna number and variable period number；Third layer; each sub-slots are made of the transmitting signal and protection interval of variable period; transmitting signal time length range determines that protection interval requirement is more than transmitting antenna switching time according to CW with frequency modulation swept bandwidth, maximum detecting distance, target relative velocity and sample frequency；4th layer, emit signal and protection interval is made of the sampling interval of integral multiple.The frame structure of the present invention uses the sub-slots and slot length of regular length, and frame structure is simpler, reduces hardware realization complexity, using the sampling interval as minimum time unit, is conducive to system time synchronization.
Description
Technical field
The invention belongs to Radar Signal Processings and technical field of automotive electronics, are related to automobile collision preventing, adaptive cruise field,
The frame structure design of specifically a kind of automobile collision avoidance radar transmitting signal.
Background technology
The research of automobile collision avoidance radar originate in the 1960s, early stage it is slower by the developmental limitation of component, with
The progress of integrated circuit in recent years, the research of Anticollision Radar becomes active.
Realize that the technology of Anticollision Radar function can be there are many selecting, such as ultrasonic ranging laser acquisition alignment system, to regard
Frequency camera shooting pattern recognition technique, infrared imagery technique, microwave, millimeter-wave technology etc..Anticollision Radar need to be in common weather conditions
It is lower to work normally, such as rain, snow, mist, in the level that certain performance can be maintained than under relatively rugged environment also than.It is coping with
In terms of various environmental aspects, millimeter wave has obvious advantage.In addition, bandwidth, wavelength are short, Atmospheric Absorption effect is apparent
It is three fundamental characteristics of millimeter wave, is summarized as follows：
1st, there is massive band width that can use, improve resolution of ranging, effectively eliminate and interfere with each other, without blind area of testing the speed.
2nd, wavelength is shorter, and beam angle is narrow, and antenna gain is high, can improve spatial resolution, while component size is small, weight
Amount is light, meets the requirement of trailer-mounted radar compact.
3rd, Atmospheric Absorption effect is stronger than microwave, and attenuation is big, is not easy to interfere with each other, and reduces electromagnetic pollution.
Automobile collision avoidance radar generally use linear frequency modulation continuous wave system (LFMCW).Linear Frequency Modulation continuous wave system thunder
In reaching, triangular wave detections of radar precision is high, and the pairing of multiple target is realized using the method for emitting different frequency sweep cycle triangular waves, is calculated
Method is simple.
At present, the frame structure design of the clear layer unified about variable period automobile collision avoidance radar neither one, cause be
Cost of implementation of uniting is higher, and practicability is poor.
Invention content
Goal of the invention:Emit the problem of signal frame structure is complicated, system cost of implementation is high for current automobile collision avoidance radar,
The present invention proposes a kind of multi-level, frame structure of low complex degree and its design method, reduces system cost of implementation.
Technical solution：A kind of variable period automobile collision avoidance radar emits signal frame structure, using the sampling interval as minimum time list
Position, time quantum are included between time slot (Time slot), sub-slots (Sub Time slot), transmitting signal duration and protection
Every the frame structure is broadly divided into four levels, specially：First layer, a frame are made of the identical time slot of multiple length；Second
Layer, a time slot are made of the identical sub-slots of multiple length；Third layer, each sub-slots by variable period transmitting signal and
Protection interval forms；4th layer, emit signal and protection interval is made of the sampling interval of integral multiple.
The slot length is TTs=TF/NTs, wherein, TFFor a frame duration, NTsFor the number of time slot, i.e. a frame is interior to be detected
Number should be not less than in a frame of system requirements and at least detect number, i.e. NTs≥NDmin, NDminFor at least detection time in a frame
Number.
The sub-slots length is TSTs=TTs/NSTs, wherein, TTsFor a slot length, NSTsFor sub-slots number, by
System transmitting antenna number NTChange times N with frequency sweep cycleCIt determines, specific method is as follows：System uses time transmitting diversity side
Formula, transmitting antenna emits identical transmitting signal successively, by NT×NRAerial array be equivalent to 1 × NTNRAerial array, then
NSTs=NTNC, wherein, NRFor reception antenna number.
The transmitting signal time length variation range is according to triangular wave swept frequency bandwidth B, maximum detecting distance rmax, it is maximum
Relative velocity vmaxWith system sampling frequency fsIt determines, specific method is as follows：
In triangular wave radar, it will be obtained after the target echo signal of reception and the mixing of transmitting signal, low-pass filtering
Intermediate-freuqncy signal, IF signal frequency expression formula are as follows：
In formula, B be triangular wave swept frequency bandwidth, T be the triangular wave swept frequency period, f0For carrier frequency, c is electromagnetic wave in freedom
The spread speed in space, r are target range, v be target relative velocity (using close to radar as just).
Echo signal maximum IF frequency is in range of interest：
fbmaxWith fsRatio be：
To make full use of entire frequency spectrum, the ratio of formula 3 should be made to determine a ratio range α close to 11~α2, so as to root
It can determine the range of variable period triangular wave swept frequency cycle T according to formula 3, as shown in formula 4：
The protection interval TGMore than transmitting antenna switching time Tswitch。
A kind of design method of variable period automobile collision avoidance radar transmitting signal frame structure, includes the following steps：
Step 1：Triangle is determined according to triangular wave swept frequency bandwidth, maximum detecting distance, relative velocity and sample frequency
Wave frequency sweep cycle range and Minimal Protective interval, protection interval requirement are more than antenna switching time；
Step 2：The number of time slots that number determines that a frame includes at least is detected according to frame length, sampling interval and a frame, to the greatest extent
No time residue is measured, obtains the length of a time slot；
Step 3：Number is changed according to system transmitting antenna number and frequency sweep cycle and determines sub-slots number, obtains a period of the day from 11 p.m. to 1 a.m
The length of gap；
Step 4：The variation range of triangular signal frequency sweep cycle is adjusted according to sub-slots length and protection interval minimum value,
It is appropriate to increase or reduce detection number (number of time slots), obtain optimal frame structure design.
Advantageous effect：Frame structure hierarchical structure proposed by the present invention is clear, compared with general frame structure, is grown using fixed
The sub-slots and slot length of degree make frame structure simpler, reduce hardware realization complexity, using the sampling interval as minimum when
Between unit, be conducive to system time synchronization.
Description of the drawings
Fig. 1 is present invention transmitting signal frame structure；
Fig. 2 is frame structure design flow chart of the present invention；
Fig. 3 is that antenna emits signal time-frequency figure in case study on implementation of the present invention；
Fig. 4 is to emit signal frame structure in case study on implementation of the present invention.
Specific embodiment
With reference to specific implementation case, the present invention is furture elucidated, it should be understood that these embodiments are merely to illustrate this hair
Bright rather than limit the scope of the invention, after the present invention has been read, those skilled in the art are various etc. to the present invention's
The modification of valency form falls within the application range as defined in the appended claims.
As shown in Figure 1, a kind of frame structure of variable period automobile collision avoidance radar, main using the sampling interval as minimum time unit
It is divided into four layers, specially：First layer, a frame are made of the time slot of multiple equal lengths；The second layer, a time slot include multiple
The identical sub-slots of length；Third layer, each sub-slots are made of the transmitting signal and protection interval of variable period, emit signal
Time span range determines that protection interval requires according to swept bandwidth, maximum detecting distance, relative velocity and sample frequency
More than transmitting antenna switching time；4th layer, emit signal and protection interval is made of the sampling interval of integral multiple.Fig. 2 is retouched
The idiographic flow of frame structure design has been stated, has been switched first according to swept bandwidth, maximum detecting distance, relative velocity, antenna
Time and sample frequency determine triangular wave swept frequency periodic regime and Minimal Protective interval, then according to a frame length, needed for a frame
The sub-slots number that includes of detection number and time slot, frame structure is divided, the timeslot number included by adjusting a frame
And the sub-slots number that time slot includes, frame structure is optimized.
In case study on implementation of the present invention, radar sends out four aerial arrays received using two, and two transmitting antennas use the side of time-division
Formula emits triangular signal successively, and Fig. 3 emits signal time-frequency figure for antenna.It is T that antenna 1, which emits frequency sweep cycle,1Triangular wave letter
Number, by protection interval TG1Aft antenna 2 emits same triangular signal, using protection interval TG1Afterwards, two antennas are with same
The mode of sample emits frequency sweep cycle as T in turn2Triangular signal, can be equivalent in this way 1 × 8 aerial array.System is joined
Number is as shown in the table：
1 system parameter setting of table
The specific design method of frame structure is as follows：
Step 1：Triangular wave swept frequency is determined according to swept bandwidth, maximum detecting distance, relative velocity and sample frequency
Periodic regime, protection interval TGIt is required that more than antenna switching time Tswitch；In triangular wave radar, in range of interest
Echo signal maximum IF frequency and sample frequency fsRatio be：
To make full use of entire frequency spectrum, it is 2/3~1 to take ratio range, and triangular wave swept frequency periodic regime is obtained according to formula 4
For 1.33 ＜ T ＜, 2 (units:Millisecond), T1And T2It is chosen in the range of from this, such as takes T1=1.5 milliseconds of (450Ts, Ts=3.33 is micro-
Second), T2=1.9 milliseconds of (570Ts)。
Step 2：According to frame length, sampling interval and a frame at least detect the number of time slots that number first determines that a frame includes,
As possible without time residue, the length of a time slot is obtained；According to frame length (15000Ts), sampling interval and a frame are at least examined
Survey times NDmin=5, a frame can be divided into six time slots, each slot length is 8.33 milliseconds of (2500Ts)。
Step 3：According to system transmitting antenna number NTWith variable period times NCIt determines sub-slots number, obtains a sub-slots
Length；System transmitting antenna number NT=2, variable period times NC=2, two transmitting antennas are emitted by the way of time diversity
Signal, as shown in Figure 3；It can obtain each time slot to be made of four sub-slots, sub-slots length is 2.08 milliseconds of (625Ts),
The middle minimum T of protection interval lengthGmin=80 microseconds, meet system requirements, and Fig. 4 is case study on implementation frame structure schematic diagram.
Step 4：According to sub-slots length and the variation range of protection interval minimum value adjustment triangular signal frequency sweep cycle；
Detection number (number of time slots) can be suitably increased or reduced, obtains optimal frame structure design.In this system, if taking NTs=5, then
Sub-slots length is 2.5 milliseconds of (750Ts), the wherein minimum T of protection interval lengthGmin=500 microseconds, time availability be not high；
If take NTs=7, then transmitting signal length variation range can be caused smaller.
Claims (3)
1. a kind of variable period automobile collision avoidance radar emits signal frame structure, it is characterised in that：The frame structure is divided into 4 levels,
Specially：First layer, a frame are made of the identical time slot of multiple length；The second layer, a time slot is by the identical son of multiple length
Time slot forms；Third layer, each sub-slots are made of the transmitting signal and protection interval of variable period；4th layer, emit signal
It is made of with protection interval the sampling interval of integral multiple；
The slot length is TTs=TF/NTs, wherein, TFFor a frame duration, NTsFor the number of time slot, and NTs≥NDmin, NDmin
At least to detect number in a frame；
The sub-slots length is TSTs=TTs/NSTs, wherein, TTsFor a slot length, NSTsFor sub-slots number, by system
Transmitting antenna number NTChange times N with frequency sweep cycleCIt determines, specific method is as follows：System uses time transmitting diversity mode, hair
It penetrates antenna and emits identical transmitting signal successively, by NT×NRAerial array be equivalent to 1 × NTNRAerial array, then NSTs=
NTNC, wherein, NRFor reception antenna number；
The transmitting signal time length variation range is according to triangular wave swept frequency bandwidth B, maximum detecting distance rmax, it is maximum opposite
Speed vmaxWith system sampling frequency fsIt determines, specific method is as follows：
In triangular wave radar, intermediate frequency will be obtained after the target echo signal of reception and the mixing of transmitting signal, low-pass filtering
Signal, IF signal frequency expression formula are as follows：
In formula, B be triangular wave swept frequency bandwidth, T be the triangular wave swept frequency period, f0For carrier frequency, c is electromagnetic wave in free space
Spread speed, r is target range, and v is target relative velocity, using close to radar as just；
Echo signal maximum IF frequency is in range of interest：
fbmaxWith fsRatio be：
To make full use of entire frequency spectrum, the ratio of formula 3 should be made to determine a ratio range α close to 11~α2, so as to according to public affairs
Formula 3 can determine the range of variable period triangular wave swept frequency cycle T, as shown in formula 4：
2. variable period automobile collision avoidance radar according to claim 1 emits signal frame structure, it is characterised in that：The protection
It is spaced TGMore than transmitting antenna switching time Tswitch。
3. emit the design method of signal frame structure according to claim 1-2 any one of them variable periods automobile collision avoidance radar,
It is characterized in that：Include the following steps：
Step 1：Determine that triangular wave is swept according to triangular wave swept frequency bandwidth, maximum detecting distance, relative velocity and sample frequency
Frequency periodic regime and Minimal Protective interval, protection interval requirement are more than antenna switching time；
Step 2：The number of time slots that number determines that a frame includes at least is detected according to frame length, sampling interval and a frame, without when
Between it is remaining, obtain the length of a time slot；
Step 3：Number is changed according to system transmitting antenna number and frequency sweep cycle and determines sub-slots number, obtains sub-slots
Length；
Step 4：According to sub-slots length and the variation range of protection interval minimum value adjustment triangular signal frequency sweep cycle, increase
Or reduce detection number, obtain optimal frame structure design.
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| CN107688178A (en) * | 2017-08-25 | 2018-02-13 | 上海通趣科技有限公司 | A kind of sawtooth waveforms ranging and range rate method based on 77GHz millimetre-wave radars |
| CN109613538B (en) * | 2018-12-20 | 2022-09-27 | 东南大学 | Dual-mode automotive detection millimeter wave radar frame structure and design method thereof |
| EP4109135A4 (en) * | 2020-03-17 | 2023-04-26 | Huawei Technologies Co., Ltd. | Signal processing method and apparatus, and storage medium |
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| CN1298234A (en) * | 1999-11-29 | 2001-06-06 | 株式会社东芝 | Code division multichannel multiplexing transmission mode and transmitting and receiving equipment |
| CN103257346A (en) * | 2013-05-15 | 2013-08-21 | 桂林电子科技大学 | Automotive anti-collision radar multi-target detecting method and system |
| KR101351282B1 (en) * | 2012-11-22 | 2014-01-15 | 국방과학연구소 | Enhancement method of unobserved area for radar system based on clutter map, and radar system using the same |
| CN103873025A (en) * | 2012-12-10 | 2014-06-18 | 北京普源精电科技有限公司 | Triangle wave signal generation method and triangle wave generator |
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2016
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Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1298234A (en) * | 1999-11-29 | 2001-06-06 | 株式会社东芝 | Code division multichannel multiplexing transmission mode and transmitting and receiving equipment |
| KR101351282B1 (en) * | 2012-11-22 | 2014-01-15 | 국방과학연구소 | Enhancement method of unobserved area for radar system based on clutter map, and radar system using the same |
| CN103873025A (en) * | 2012-12-10 | 2014-06-18 | 北京普源精电科技有限公司 | Triangle wave signal generation method and triangle wave generator |
| CN103257346A (en) * | 2013-05-15 | 2013-08-21 | 桂林电子科技大学 | Automotive anti-collision radar multi-target detecting method and system |
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