CN109581369A - The radar altimeter of non-homogeneous multichannel perseverance difference frequency system - Google Patents
The radar altimeter of non-homogeneous multichannel perseverance difference frequency system Download PDFInfo
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- CN109581369A CN109581369A CN201910072927.9A CN201910072927A CN109581369A CN 109581369 A CN109581369 A CN 109581369A CN 201910072927 A CN201910072927 A CN 201910072927A CN 109581369 A CN109581369 A CN 109581369A
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- high period
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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
- G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
- G01S13/88—Radar or analogous systems specially adapted for specific applications
- G01S13/882—Radar or analogous systems specially adapted for specific applications for altimeters
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01C—MEASURING DISTANCES, LEVELS OR BEARINGS; SURVEYING; NAVIGATION; GYROSCOPIC INSTRUMENTS; PHOTOGRAMMETRY OR VIDEOGRAMMETRY
- G01C5/00—Measuring height; Measuring distances transverse to line of sight; Levelling between separated points; Surveyors' levels
- G01C5/005—Measuring height; Measuring distances transverse to line of sight; Levelling between separated points; Surveyors' levels altimeters for aircraft
Abstract
The invention discloses the radar altimeter of non-homogeneous multichannel perseverance difference frequency system, mainly solve the problems, such as that radar altimeter is poor in the low and high height system real-time performance of low clearance system sensitivity in the prior art.Comprising: microwave components module (1), analog-to-digital conversion module (2) and digital processing module (3), the output end of microwave components module (1) is connected with the input terminal of analog-to-digital conversion module (2), simulation Beat Signal is provided for it, the output end of analog-to-digital conversion module (2) is connected with the input terminal of digital processing module (3), digital signal is provided for it, the output end of digital processing module (3) is connected with the input terminal of microwave components module (1), provides the modulation parameter of transmitting signal for it.The present invention has taken into account the characteristics of low-height sensitive degree height and high height fast data transfer rate, and has strong antijamming capability, and later maintenance cost is low and the high advantage of measurement accuracy, can be used for the measurement to aircraft aircraft altitude.
Description
Technical field
The invention belongs to Radar Signal Processing Technology fields, and in particular to a kind of radar altimeter can be used for aircraft
The measurement of aircraft altitude.
Background technique
With the development of modern Aviation, radar altimeter in various aircraft using more and more extensive, such as helicopter
Determine height spiral, automatic Pilot and the flight of low-level missile etc., and whether there is or not blind range zone, precision for frequency modulated continuous wave radar altimeter
It is high, light-weight, structure is simple, very more advantage such as low in energy consumption；Existing radar altimeter is based primarily upon single constant beat
Frequency and uniform multichannel two kinds of working systems of constant difference frequency, there is height real-time is poor, low-height sensitive degree is low
The disadvantages of.
Currently used radar altimeter is the working system based on single constant difference frequency, such as Chinese gongwu
The radar altimeter that the paper " research of fmcw radar altimeter Digital Signal Processing " of research institute master Yang Yi is introduced,
It is implemented as, firstly, obtaining simulation Beat Signal from the frequency mixer of radar altimeter front end and carrying out A/D sampling；Then not
The modulation time of disconnected adjustment transmitting signal, when obtained difference frequency is fallen in setting narrow band filter free transmission range, FFT it
Frequency spectrum afterwards is greater than effective output of thresholding by having, and altimeter enters tracking mode at this time, finally according to the tune of transmitting signal
Current level value is calculated in parameter processed.Patent application " a kind of Modulation Continuous Wave Radar that BJ University of Aeronautics & Astronautics mentions
The list that the digitalized processing method of altimeter " (201210166779.5 publication number CN 102707275B of patent application CN) is announced
The radar altimeter of the working system of one constant difference frequency, although the altimeter improves survey height using Chirp-Z converter technique
Precision, but this method is still without solving the problems, such as that low-height sensitive degree is low and height real-time performance is poor；This single perseverance
Determine the radar altimeter of difference frequency somatotypes, the flexibility of system and adaptive faculty are poor.
Paper " fmcw radar altimeter signal Study on processing method and the reality of Xian Electronics Science and Technology University master Liao Zhijia
It is the radar altimeter based on the constant difference frequency system of uniform channel provided in now ", which is by 4 centers
Frequency is respectively set as 25kHz, 50kHz, 75kHz and 100kHz, and the height of measurement is 0m-12000m, every under tracking mode
3000m distributes a channel, since the difference frequency of height and setting all evenly distributes, so causing to adopt in low clearance
Number of samples is very few, the sensitivity decrease of system, and threshold sets are complicated, is highly prone to the interference of noise, and in height 9000m-
In the measurement of 12000m, for the constant difference frequency due to using for 100kHz, the modulation time for emitting signal is still too long, causes
The real-time of sampling number redundancy, system is poor；Simultaneously because structure of the system using FPGA+DSP, be related to FPGA with
Data transmission and the conversion of data type between DSP will lead to precision reduction, and the hardware circuit design of framework is complicated.
Since the above method can not combine radar altimeter system sensitivity height and system when height in low clearance
The good feature of real-time of uniting, and there is no fault self-checking function in the device, later maintenance cost is very high, and the present invention is used based on non-
The radar altimeter of uniform multichannel perseverance difference frequency system solves the above problem, and all digital signal processings by
FPGA is individually completed, and hardware design is simple.
Summary of the invention
It is an object of the invention in view of the above shortcomings of the prior art, provide a kind of non-homogeneous multichannel perseverance difference frequency
The radar altimeter and the high method of survey of system, to improve the sensitivity of the system when being less than the low clearance of 20m, raising is being greater than
System real time energy when 6000m high height.
To achieve the above object, radar altimeter of the invention includes: microwave components module, analog-to-digital conversion module and number
The input terminal of processing module, analog-to-digital conversion module is connected with microwave components module output end, and output end is defeated with digital processing module
Enter end to be connected, the output end of digital processing module is connected with microwave components module input, it is characterised in that: digital processing module
Include:
Signal processing submodule, for calculating aircraft by the signal processing method of non-homogeneous multichannel perseverance difference frequency
Altitude information；
Self-test submodule, for detecting whether microwave components work normally, microwave components module and digital processing module it
Between whether normal communication；
Sub-module stored, for store cable delay height and when aircraft is parked in ground with zero elevation existing for ground
Value.
Further, the signal processing submodule is equipped with search passage and tracking channel；
The height of aircraft flight is roughly calculated out by repeatedly searching for for the search passage；
The tracking channel is divided into 5 different subchannels of frequency, for accurately finding out height on the basis of search passage
Altitude information is reached aircraft display screen by ARINC429 communication protocol by data；
It is freely converted between search passage and tracking channel, i.e., after search passage continuous 5 times search altitude information,
Corresponding tracking subchannel is selected according to the height searched out；When tracking loss, tracking channel is closed, and is transferred to search passage.
Further, the self-test submodule is divided into power-on self-test, period self-test and is enabled self-test, i.e., in system
Whether carry out power-on self-test is worked normally to the receiving channel of microwave components before working normally after electricity, in system worked well
When it is every cross 10s whether the receiving channel of microwave components is worked normally and to digital processing module transfer to microwave components module
Transmitting signal modulation parameter whether correctly carry out period self-test, the external world to altimeter issue detection instruction when to microwave components
Receiving channel whether work normally and to the transmitting signal modulation parameter of digital processing module transfer to microwave components module
Whether correctly carry out being enabled self-test；Result after these three self-tests reaches aircraft display screen by universal serial bus.
Further, when the described sub-module stored storage cable delay height and aircraft are parked in ground and existing for ground
Zero elevation value is that zero elevation value is passed through I2C agreement is write in storage chip EEPROM, to power on use next time in altimeter
When directly from EEPROM read zero elevation value, it is no longer necessary to repeat zero elevation calibration.
To achieve the above object, the present invention carries out surveying high method using above-mentioned radar altimeter, which is characterized in that including
Following steps:
1) by self-test, failure is judged whether there is:
Whether microwave components module is worked normally, between microwave components module and digital processing module whether normal communication
It is detected:
If communicating failure between microwave components module and microwave components module and digital processing module, execute
9)；
It does not break down, holds if communicated between microwave components module and microwave components module and digital processing module
Row 2)；
2) oscillator in microwave components module generates transmitting signal according to modulation parameter and is sent out by transmitting antenna
Out, power on survey for the first time afterwards the high period the modulation time be 200us, hereafter modulation bandwidth 150MHz, transmission power 0dbm are surveyed
The modulation parameter in high period is sent to microwave components module by digital processing module.
3) the reception signal that receiving antenna receives is mixed by the frequency mixer in microwave components module with transmitting signal,
Simulation Beat Signal is obtained, and A/D sampling is carried out by analog-to-digital conversion module and is translated into digital Beat Signal；
4) all digital Beat Signals are averaging, obtain the average value m of digital Beat Signal, will be greater than the number of m
Beat Signal is averaging to obtain the average value n that amplitude is higher than center amplitude value signal again, finds out digital Beat Signal using n-m
Amplitude V；
5) it selects corresponding filtering channel to be filtered digital Beat Signal according to current system working condition, will filter
Signal afterwards carries out Fast Fourier Transform (FFT), finds out the global frequency spectrum M of digital Beat Signal；
6) working condition of decision height table:
6a) calculate threshold value:Wherein T represent transmitting signal the modulation time, K with modulation the time variation and
Variation；
6b) ought overall situation frequency spectrum M be compared with threshold value D:
If there is the frequency point greater than threshold value D in global frequency spectrum M, detect frequency spectrum forward position, execute 6c)；
If in global frequency spectrum M, there is no the frequency points greater than threshold value D, and frequency spectrum forward position is not detected, executes 6d)；
If 6c) continuous 5 surveys high period can detect frequency spectrum forward position, system is judged as tracking mode, is executed 7),
Otherwise, system is judged as search condition, executed 8)；
The current working condition of system 6d) is judged in the previous working condition for surveying the high period according to system:
If system is in search condition in the previous survey high period, system is judged to search condition, is executed 8)；
Before if system is in tracking mode in the previous survey high period, and frequency spectrum is not detected in continuous 3 surveys high period
System is then judged to search condition by edge, is executed 8), otherwise, is judged to tracking mode, is executed 7)；
7) flying height of calculating aircraft:
The frequency spectrum forward position detected under tracking mode is brought into following expression, this height for surveying the high period is calculated
Degree evidence:Wherein, c represents electromagnetic wave propagation speed, and f represents the frequency spectrum forward position value detected under tracking mode, T
The modulation time of transmitting signal is represented, B represents the modulation bandwidth of transmitting signal；
8) next modulation parameter for surveying the high period is determined:
If 8a) under tracking mode, the modulation parameter for surveying the high period next time is as follows for system work:
Modulation bandwidth B is fixed on 150MHz；
According to currently surveying the altitude information h that the high period obtains under tracking mode, when determining next modulation for surveying the high period
Between:C represents the speed of Electromagnetic Wave Propagation in formula, and h represents the altitude information for currently surveying the high period, and B represents transmitting
The modulation bandwidth of signal, F represent constant difference frequency value；
According to the altitude information h for currently surveying the high period under tracking mode, next transmission power P for surveying the high period is determined:
Wherein, h represents the altitude information for currently surveying the high period；
If 8b) system work is under search condition, next modulation parameter for surveying the high period is as follows:
Modulation bandwidth B is fixed on 150MHz；
Next modulation time for surveying the high period:Wherein, TnRepresentative is worked as
The preceding modulation time for surveying the high period；
Transmission power:
9) data export:
9a) by the altimeter working condition 6) obtained and 7) in altitude information h or fault code passed by ARIN429 agreement
It send to aircraft display screen and is referred to for pilot；
9b) 8) the transmitting signal modulation parameter of the next measurement period obtained is passed through serial transmission by digital processing module
Mode reaches microwave components module.
The present invention has the advantage that compared with prior art
First, signal processing submodule of the invention is due to the signal processing side using non-homogeneous multichannel perseverance difference frequency
Method calculating aircraft height not only overcomes system in the low disadvantage low with measurement accuracy of 20m or less sensitivity, but also solves
Problem of the system in 6000m or more real-time performance difference.
Second, whether microwave components are worked normally due to self-test submodule in the present invention, microwave components module and number
Whether normal communication is detected between processing module, reduces the maintenance cost in radar altimeter later period.
Third, when the present invention is parked in ground to cable delay height and aircraft by sub-module stored and existing for ground
Zero elevation value is stored, and solves the repetitive operation of zero elevation calibration, meanwhile, height can be made by storing different zero elevation values
Table works in different types of aircraft, and versatility is extremely strong.
4th, digital signal processing of the invention is individually completed by FPGA, and circuit structure is simple, by adverse circumstances
Influence factor is smaller, can in complex environment steady operation, adaptability it is extremely strong.
Detailed description of the invention
Fig. 1 is overall structure block diagram of the invention；
Fig. 2 is the signal processing sub-modular structure block diagram in the present invention；
Fig. 3 is the work flow diagram of altimeter of the present invention.
Specific embodiment:
Below in conjunction with attached drawing of the invention, the present invention is further described.
Referring to Fig. 1, radar altimeter of the invention includes microwave components module 1, analog-to-digital conversion module 2 and digital processing mould
The output end of block 3, microwave components module 1 is connected with the input terminal of analog-to-digital conversion module 2；The output end of analog-to-digital conversion module 2 with
The input terminal of digital processing module 3 is connected, which is sampled by A/D and convert 14 for simulation Beat Signal
Digital Beat Signal and send to digital processing module 3；The output end of digital processing module 3 and the input of microwave components module 1
End is connected, and provides the modulation parameter of transmitting signal for microwave components module 1.
1 module of microwave components mainly includes transmitting antenna, receiving antenna, oscillator and frequency mixer；Oscillator generates hair
Penetrate signal and issued by transmitting antenna, frequency mixer by signal that receiving antenna receives with emit the analogue difference after signal is mixed
Signal is clapped to send to analog-to-digital conversion module 2.
The digital processing module 3 includes signal processing submodule 31, self-test submodule 32 and sub-module stored 33, three sons
Module is mutually indepedent, is realized by the Xilinx Kintex-7 Series FPGA of model xc7k410tiffg900-2L.Its
In:
Signal processing submodule 31, for calculating aircraft by the working system of non-homogeneous multichannel perseverance difference frequency
Altitude information.
Self-test submodule 32, for detecting whether microwave components work normally, microwave components module and digital processing module
Between whether normal communication；It is divided into power-on self-test, period self-test and is enabled 3 seed type of self-test, and power-on self-test is in system
It is detected after electricity and before working normally to whether the receiving channel of microwave components works normally；Period self-test is in system
It is every when normal work to cross whether 10s works normally the receiving channel of microwave components and to digital processing module transfer to microwave
Whether the transmitting signal modulation parameter of assembly module is correctly detected；Being enabled self-test is to issue detection to altimeter in the external world to refer to
Whether the receiving channel of microwave components is worked normally when enabling and the hair to digital processing module transfer to microwave components module
Penetrate whether signal modulation parameter is correctly detected；Result after these three self-tests reaches aircraft display screen by universal serial bus.
Sub-module stored 33, for store cable delay height and when aircraft is parked in ground with zero elevation existing for ground
Value, after receiving external zero elevation calibration command, which is that zero elevation value is passed through I2C agreement writes storage chip
In EEPROM, with when altimeter powers on use next time directly from EEPROM read zero elevation value, it is no longer necessary to repeat into
The calibration of row zero elevation.
Referring to fig. 2, the signal processing submodule 31, including search passage 311 and tracking channel 312, tracking channel
312 are equipped with non-homogeneous 5 subchannels for being incremented by constant difference frequency of 10kHz, 40kHz, 70kHz, 120kHz and 180kHz, are flying
When row device is less than the height of 20m, constant beat channel frequence is set as 10kHz, so that sampling number increases, improves signal-to-noise ratio,
Reduce elevation carrection error；When aircraft is greater than the height of 6000m, constant beat channel frequence is set as 180kHz, is modulated
Time shortens, and system real time can be improved；Different channels are equipped with different bandpass filters, what search passage 311 was set
The free transmission range of filter is 10kHz~150kHz, in 5 subchannels of tracking channel 312, the narrowband of the first subchannel setting
The free transmission range of filter is 7kHz~13kHz, and measurement range is the height of 0m~20m, the narrowband filter of the second subchannel setting
The free transmission range of wave device is 37kHz~43kHz, and measurement range is the height of 20m~1000m, the narrowband of third subchannel setting
The free transmission range of filter is 67kHz~73kHz, and measurement range is the height of 1000m~3000m, the setting of the 4th subchannel
The free transmission range of narrow band filter is 117kHz~123kHz, and measurement range is the height of 3000m~6000m, the 5th subchannel
For the free transmission range of the narrow band filter set as 177kHz~183kHz, measurement range is the height of 6000m~10000m.
Referring to Fig. 3, high to the survey of altimeter of the present invention steps are as follows:
Step 1, self-test.
Whether self-test submodule works normally microwave components module, is between microwave components module and digital processing module
No normal communication is detected.
Step 2, failure is judged whether there is.
If communicating failure between microwave components module and microwave components module and digital processing module, step is executed
Rapid 10, it does not break down, executes if communicated between microwave components module and microwave components module and digital processing module
Step 3.
Step 3, modulated signal is sent.
Oscillator in microwave components module generates transmitting signal according to modulation parameter and is issued by transmitting antenna,
Powering on and surveying the modulation time in high period for the first time afterwards is 200us, modulation bandwidth 150MHz, transmission power 0dbm, is hereafter surveyed high
The modulation parameter in period is sent to microwave components module by digital processing module.
Step 4, digital Beat Signal is extracted
The reception signal that receiving antenna receives be mixed with transmitting signal by the frequency mixer in microwave components module
To simulation Beat Signal, and A/D sampling is carried out by analog-to-digital conversion module and is translated into digital Beat Signal.
Step 5, Beat Signal amplitude calculates.
All digital Beat Signals are averaging, the average value m of digital Beat Signal is obtained, will be greater than the digital difference of m
It claps signal to be averaging to obtain the average value n that amplitude is higher than center amplitude value signal again, the width of digital Beat Signal is found out using n-m
Spend V；
Step 6, filtering and Fast Fourier Transform (FFT).
(6a) will be surveyed for the first time after system electrification digital Beat Signal that the high period obtains by search passage 10kHz~
The bandpass filter of 150kHz is filtered；The digital Beat Signal that the survey high period after this receives, according to system shape
State selects corresponding channel:
If current system works in search condition, the digital Beat Signal for currently surveying the high period uses search passage
The bandpass filter of 10kHz~150kHz is filtered；
If current system works in tracking mode, the bandpass filter for corresponding to subchannel in tracking channel is selected to carry out
Filtering；
Filtered signal is carried out Fast Fourier Transform (FFT) by (6b), finds out the global frequency spectrum M of Beat Signal.
Step 7, the working condition of decision height table.
Threshold value is calculated according to the Beat Signal amplitude V found out in step 5 in (7a)
Wherein T represents the modulation time of transmitting signal, and K changes with the variation of modulation time, as shown in table 1
Table 1K value changes table
(7b) ought overall situation frequency spectrum M be compared with threshold value D:
If there is the frequency point greater than threshold value D in global frequency spectrum M, detects frequency spectrum forward position, execute step (7c)；
If in global frequency spectrum M, there is no the frequency points greater than threshold value D, and frequency spectrum forward position is not detected, executes step
(7d)；
System is judged as tracking mode, executes step by (7c) if continuous 5 are surveyed the high period and can detect frequency spectrum forward position
Rapid 8, otherwise, system is judged as search condition, executes step 9；
(7d) judges the current working condition of system in the previous working condition for surveying the high period according to system:
If system is in search condition in the previous survey high period, system is judged to search condition, executes step 9；
Before if system is in tracking mode in the previous survey high period, and frequency spectrum is not detected in continuous 3 surveys high period
System is then judged to search condition by edge, executes step 9, otherwise, is judged to tracking mode, is executed step 8；
Step 8, the flying height of calculating aircraft.
The frequency spectrum forward position detected under tracking mode is brought into following expression, this height for surveying the high period is calculated
Degree is according to h:
Wherein, c represents electromagnetic wave propagation speed, and f represents the frequency spectrum forward position value detected under tracking mode, and T represents hair
It penetrates the modulation time of signal, B represents the modulation bandwidth of transmitting signal.
Step 9, next modulation parameter for surveying the high period is determined.
(9a) if system work is under tracking mode, the modulation parameter for surveying the high period next time is as follows:
Modulation bandwidth B is fixed on 150MHz；
According to currently surveying the altitude information h that the high period obtains under tracking mode, when determining next modulation for surveying the high period
Between Tn+1:
C represents the speed of Electromagnetic Wave Propagation in formula, and h represents the altitude information for currently surveying the high period, and B represents transmitting signal
Modulation bandwidth, F represent constant difference frequency value, as shown in table 2.
The corresponding constant difference frequency value of 2 difference h of table
According to the altitude information h that the high period obtains currently is surveyed under tracking mode, next transmitting function for surveying the high period is determined
Rate P:
H in formula represents the altitude information for currently surveying the high period, and being divided transmission power P according to it is 0~1500m, 1500m
Tri- sections~6000m and 6000m~10000m；
(9b) if system work is under search condition, next modulation parameter for surveying the high period is as follows:
Modulation bandwidth B is fixed on 150MHz；
Next modulation time T for surveying the high periodn+1:
Wherein, TnRepresent the modulation time for currently surveying the high period；
Transmission power P:
Step 10, data export.
The final altitude information h or fault code that (10a) obtains altimeter working condition and step 8 that step 7 obtains
Aircraft display screen is sent to by ARIN429 agreement to refer to for pilot.
The transmitting signal modulation parameter in next survey high period that step 9 acquires is passed through string by (10b) digital processing module
Row transmission mode reaches microwave components module.
Above description is only a specific implementation of the invention, does not constitute any limitation of the invention, it is clear that for
It, all may be without departing substantially from the principle of the invention, structure after having understood the content of present invention and principle for one of skill in the art
In the case where, carry out various modifications and change in form and details, but these modifications and variations based on inventive concept
Still within the scope of the claims of the present invention.
Claims (8)
1. the radar altimeter based on non-homogeneous multichannel perseverance difference frequency system, comprising: microwave components module (1), modulus turn
Change the mold block (2) and digital processing module (3), input terminal and microwave components module (1) the output end phase of analog-to-digital conversion module (2)
Even, output end is connected with digital processing module (3) input terminal, the output end of digital processing module (3) and microwave components module (1)
Input terminal is connected, it is characterised in that: digital processing module (3) includes:
Signal processing submodule (31), for calculating the altitude information of aircraft；
Self-test submodule (32), for detecting whether microwave components work normally, microwave components module and digital processing module it
Between whether normal communication；
Sub-module stored (33), for store cable delay height and when aircraft is parked in ground with zero elevation existing for ground
Value.
2. radar altimeter according to claim 1, it is characterised in that: the signal processing submodule (31) is equipped with and searches
Suo Tongdao (311) and tracking channel (312)；
The height of aircraft flight is roughly calculated out by repeatedly searching for for the search passage (311)；
The tracking channel (312) is divided into 5 different subchannels of frequency, for accurately finding out height on the basis of search passage
Altitude information is reached aircraft display screen by ARINC429 communication protocol by degree evidence；
It is freely converted between search passage (311) and tracking channel (312), i.e., searches high degree at search passage continuous 5 times
According to later, corresponding tracking subchannel is selected according to the height searched out；When tracking loss, tracking channel is closed, and is transferred to and is searched
Suo Tongdao.
3. radar altimeter according to claim 2, it is characterised in that: 5 subchannels of tracking channel (312), respectively
It is the non-homogeneous incremental constant difference frequency of 10kHz, 40kHz, 70kHz, 120kHz and 180kHz, is less than 20m in aircraft
Height when, constant beat channel frequence is set as 10kHz, so that sampling number increases, signal-to-noise ratio is improved, reduces elevation carrection
Error；When aircraft is greater than the height of 6000m, constant beat channel frequence is set as 180kHz, the modulation time shortens, system
Real-time performance is improved.
4. altimeter according to claim 1, it is characterised in that: the self-test submodule (32) is divided into and powering on certainly
Just whether inspection and is enabled self-test at period self-test, i.e., before working normally after system electrification to the receiving channel of microwave components
Often work carry out power-on self-test, in system worked well it is every cross 10s to the receiving channel of microwave components whether work normally with
And whether period self-test is correctly carried out to the transmitting signal modulation parameter of digital processing module transfer to microwave components module, outside
Whether boundary works normally the receiving channel of microwave components when issuing detection instruction to altimeter and passes to digital processing module
Whether the transmitting signal modulation parameter for transporting to microwave components module correctly carries out being enabled self-test；Result after these three self-tests passes through
Universal serial bus reaches aircraft display screen.
5. altimeter according to claim 1, it is characterised in that: sub-module stored (33) the storage cable delay is high
It is that zero elevation value is passed through into I with zero elevation value existing for ground when degree and aircraft are parked in ground2C agreement writes storage chip
In EEPROM, to read zero elevation value directly from EEPROM when altimeter powers on use next time, carry out zero is not repeated
Altitude calibration.
6. radar altimeter according to claim 1, it is characterised in that: the microwave components module (1) includes transmitting
Antenna, receiving antenna, oscillator and frequency mixer, according to the modulation parameter that digital processing module provides, oscillator generates linear adjust
Frequency signal simultaneously issued as transmitting signal by transmitting antenna, and after time delay, receiving antenna will be received
After signal is mixed with transmitting signal by frequency mixer, obtains simulation Beat Signal and be sent to analog-to-digital conversion module (2).
7. altimeter according to claim 1, it is characterised in that: the signal processing submodule (31), self-test submodule
Block (32) and sub-module stored (33) are realized by FPGA.
8. carrying out surveying high method using radar altimeter described in claim 1, it is characterised in that: include the following:
1) by self-test, failure is judged whether there is:
Whether microwave components module is worked normally, whether normal communication carries out between microwave components module and digital processing module
Detection:
If communicating failure between microwave components module and microwave components module and digital processing module, execute 9)；
It does not break down, executes if communicated between microwave components module and microwave components module and digital processing module
2)；
2) oscillator in microwave components module generates transmitting signal according to modulation parameter and is issued by transmitting antenna, on
The modulation time for surveying the high period after electricity for the first time is 200us, modulation bandwidth 150MHz, transmission power 0dbm, hereafter surveys high week
The modulation parameter of phase is sent to microwave components module by digital processing module.
3) the reception signal that receiving antenna receives is mixed by the frequency mixer in microwave components module with transmitting signal, is obtained
Beat Signal is simulated, and A/D sampling is carried out by analog-to-digital conversion module and is translated into digital Beat Signal；
4) all digital Beat Signals are averaging, obtain the average value m of digital Beat Signal, will be greater than the digital beat of m
Signal is averaging to obtain the average value n that amplitude is higher than center amplitude value signal again, and the amplitude of digital Beat Signal is found out using n-m
V；
5) corresponding filtering channel is selected to be filtered digital Beat Signal according to current system working condition, it will be filtered
Signal carries out Fast Fourier Transform (FFT), finds out the global frequency spectrum M of digital Beat Signal；
6) working condition of decision height table:
6a) calculate threshold value:Wherein T represents the modulation time of transmitting signal, and K changes with the variation of modulation time；
6b) ought overall situation frequency spectrum M be compared with threshold value D:
If there is the frequency point greater than threshold value D in global frequency spectrum M, detect frequency spectrum forward position, execute 6c)；
If in global frequency spectrum M, there is no the frequency points greater than threshold value D, and frequency spectrum forward position is not detected, executes 6d)；
If 6c) continuous 5 surveys high period can detect frequency spectrum forward position, system is judged as tracking mode, is executed 7), it is no
Then, system is judged as search condition, executed 8)；
The current working condition of system 6d) is judged in the previous working condition for surveying the high period according to system:
If system is in search condition in the previous survey high period, system is judged to search condition, is executed 8)；
If system is in tracking mode in the previous survey high period, and frequency spectrum forward position is not detected in continuous 3 surveys high period, then
System is judged to search condition, is executed 8), otherwise, tracking mode is judged to, executes 7)；
7) flying height of calculating aircraft:
The frequency spectrum forward position detected under tracking mode is brought into following expression, this high degree for surveying the high period is calculated
According to:Wherein, c represents electromagnetic wave propagation speed, and f represents the frequency spectrum forward position value detected under tracking mode, and T is represented
Emit the modulation time of signal, B represents the modulation bandwidth of transmitting signal；
8) next modulation parameter for surveying the high period is determined:
If 8a) under tracking mode, the modulation parameter for surveying the high period next time is as follows for system work:
Modulation bandwidth B is fixed on 150MHz；
According to the altitude information h that the high period obtains currently is surveyed under tracking mode, next modulation time for surveying the high period is determined:C represents the speed of Electromagnetic Wave Propagation in formula, and h represents the altitude information for currently surveying the high period, and B represents transmitting signal
Modulation bandwidth, F represents constant difference frequency value；
According to the altitude information h for currently surveying the high period under tracking mode, next transmission power P for surveying the high period is determined:
Wherein, h represents the altitude information for currently surveying the high period；
If 8b) system work is under search condition, next modulation parameter for surveying the high period is as follows:
Modulation bandwidth B is fixed on 150MHz；
Next modulation time for surveying the high period:Wherein, TnRepresent current survey
The modulation time in high period；
Transmission power:
9) data export:
9a) by the altimeter working condition 6) obtained and 7) in altitude information h or fault code be sent to by ARIN429 agreement
Aircraft display screen is referred to for pilot；
9b) 8) the transmitting signal modulation parameter of the next measurement period obtained is passed through serial transmission mode by digital processing module
Reach microwave components module.
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| CN113534145A (en) * | 2021-09-16 | 2021-10-22 | 北京安达维尔航空设备有限公司 | Altimeter height measurement method and system based on linear frequency modulation continuous wave system |
| CN114427871A (en) * | 2022-04-07 | 2022-05-03 | 烟台初心航空科技有限公司 | Aviation altimeter application efficiency detection method based on dynamic continuous detection |
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