CN107070832B - A kind of high dynamic UAV TT & C signal carrier tracking method - Google Patents
A kind of high dynamic UAV TT & C signal carrier tracking method Download PDFInfo
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- CN107070832B CN107070832B CN201611195523.1A CN201611195523A CN107070832B CN 107070832 B CN107070832 B CN 107070832B CN 201611195523 A CN201611195523 A CN 201611195523A CN 107070832 B CN107070832 B CN 107070832B
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L27/00—Modulated-carrier systems
- H04L27/26—Systems using multi-frequency codes
- H04L27/2601—Multicarrier modulation systems
- H04L27/2647—Arrangements specific to the receiver only
- H04L27/2655—Synchronisation arrangements
- H04L27/2657—Carrier synchronisation
- H04L27/266—Fine or fractional frequency offset determination and synchronisation
-
- 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
- G01S19/00—Satellite radio beacon positioning systems; Determining position, velocity or attitude using signals transmitted by such systems
- G01S19/01—Satellite radio beacon positioning systems transmitting time-stamped messages, e.g. GPS [Global Positioning System], GLONASS [Global Orbiting Navigation Satellite System] or GALILEO
- G01S19/13—Receivers
- G01S19/24—Acquisition or tracking or demodulation of signals transmitted by the system
- G01S19/29—Acquisition or tracking or demodulation of signals transmitted by the system carrier including Doppler, related
-
- 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
- G01S19/00—Satellite radio beacon positioning systems; Determining position, velocity or attitude using signals transmitted by such systems
- G01S19/01—Satellite radio beacon positioning systems transmitting time-stamped messages, e.g. GPS [Global Positioning System], GLONASS [Global Orbiting Navigation Satellite System] or GALILEO
- G01S19/13—Receivers
- G01S19/35—Constructional details or hardware or software details of the signal processing chain
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L27/00—Modulated-carrier systems
- H04L27/0014—Carrier regulation
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L7/00—Arrangements for synchronising receiver with transmitter
- H04L7/02—Speed or phase control by the received code signals, the signals containing no special synchronisation information
- H04L7/033—Speed or phase control by the received code signals, the signals containing no special synchronisation information using the transitions of the received signal to control the phase of the synchronising-signal-generating means, e.g. using a phase-locked loop
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- Engineering & Computer Science (AREA)
- Computer Networks & Wireless Communication (AREA)
- Signal Processing (AREA)
- Radar, Positioning & Navigation (AREA)
- Remote Sensing (AREA)
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Stabilization Of Oscillater, Synchronisation, Frequency Synthesizers (AREA)
- Digital Transmission Methods That Use Modulated Carrier Waves (AREA)
Abstract
The present invention provides a kind of high dynamic UAV TT & C signal carrier tracking method, it include: that intermediate-freuqncy signal is formed by I, Q two paths of data tectonic knot function I (k)+jQ (k) through Digital Down Convert, the orthogonal local trace carrier wave that variable digital controlled oscillator is generated constructs plural formBy I (k)+jQ (k) withCarry out complex mixing；Identification result is calculated using the real and imaginary parts of complex mixing result；Loop filter adjusts control parameter according to identification result, and control result is sent to variable digital controlled oscillator；Variable digital controlled oscillator adjusts frequency control word and phase control words according to control result, returns to the first step, realizes closed-loop control.The present invention has preferably taken into account the requirement of dynamic and tracking accuracy, has preferable dynamically adapting ability, constringency performance and tracking accuracy, while having the advantages that computation complexity is low and being easy to Project Realization, has good application value.
Description
Technical field
The present invention relates to wireless communication fields, more particularly, to a kind of high dynamic UAV TT & C signal carrier track side
Method.
Background technique
Due to the particularity of Telemetry System of UAV, composition includes repeater satellite, ground control station, unmanned aerial vehicle platform three
Part, system communication distance is remote, unmanned aerial vehicle platform movement velocity is fast, therefore the signal that unmanned aerial vehicle platform receives has extremely low letter
Make an uproar ratio, high-doppler dynamic the features such as.According to the special usage scenario of unmanned plane and mission requirements background, UAV's telecomma
The requirement of real-time of process for system processing is very high.In Telemetry System of UAV, carrier tracking loop is most fragile in receiver
One ring, receiver losing lock caused by high dynamic signal is often that will lead to entire survey as caused by carrier tracking loop losing lock first
System communication link is controlled to interrupt.
In Telemetry System of UAV using it is more be QPSK modulation system, QPSK is the modulation system of suppressed carrier,
Receiver end needs to realize carrier track by the way of coherent demodulation, recovers coherent carrier, this coherent carrier Ying Yufa
The carrier wave of sending end, with frequency, keeps certain synchronized relation in frequency in phase.That is, process there are two it: first is that carrying
The capture of wave frequency rate, second is that the tracking of carrier phase.
Realizing carrier auxiliary, generally there are two types of methods: one is open loop restoring methods, it is the frequency deviation directly to transmitting-receiving carrier wave
Estimated with phase error, gives effective supplement in demodulation；Another kind is closed loop restoring method, frequently with digital phase-locked loop
To realize the capture and tracking of carrier wave.For open loop approach, synchronization time is short, and structure is simple, and computational efficiency is high, but synchronous essence
It spends not high；And closed-loop fashion can reach higher synchronization accuracy, system performance is preferable, but the time that it is established is longer.
Phaselocked loop (PLL) directly tracks carrier phase, with good Phase Tracking precision and noise resisting ability, but
In the case where high dynamic, due to being affected for Doppler frequency shift, the tracking accuracy of PLL will be reduced, can only be by increasing ring
Road bandwidth is coped with.And the increase of loop bandwidth will necessarily cause the increase of noise, therefore also will affect tracking accuracy.Frequency locking ring
(FLL) carrier frequency is only tracked, the output of frequency discriminator is carrier frequency tracking error, has preferable dynamic.
The advantages of based on PLL and FLL, realizes carrier wave using the mode that FLL and PLL are combined at present and Phase Tracking is general
All over a kind of mode used, the design frame chart of current more commonly used FLL auxiliary PLL carrier tracking loop as shown in Figure 1, master
It include: the modules such as variable NCO (digital controlled oscillator), frequency mixer, low-pass filter, frequency discriminator, phase discriminator, loop filter.
Although this mode combined has its advantage, but there is also many disadvantages: this carrier tracking loop is needed using a large amount of number
Word unit is realized, such as filter (FIR), digital multiplier, digital addition and subtraction musical instruments used in a Buddhist or Taoist mass, and frequency discrimination algorithm and phase demodulation algorithm ratio
It is more complex, it is related to arriving very much the multiplication and division arithmetic of trigonometric function, is unfavorable for Project Realization.
Summary of the invention
It is an object of the invention to: in view of the problems of the existing technology, provide a kind of high dynamic UAV TT & C signal
The problem of carrier wave tracing method, a large amount of modules need to be used by solving existing tracking ring, and algorithm is complicated, be unfavorable for Project Realization.
Goal of the invention of the invention is achieved through the following technical solutions:
A kind of high dynamic UAV TT & C signal carrier tracking method, which is characterized in that the method comprising the steps of:
1) intermediate-freuqncy signal is formed by I, Q two paths of data tectonic knot function I (k)+jQ (k) through Digital Down Convert, it will
The orthogonal local trace carrier wave that variable digital controlled oscillator generates constructs plural form
2) by I (k)+jQ (k) withCarry out complex mixing；
3) identification result is calculated using the real and imaginary parts of complex mixing result；
4) loop filter adjusts control parameter according to identification result, and control result is sent to variable numerical control and is vibrated
Device；
5) can be changed digital controlled oscillator and frequency control word and phase control words, return step 1 adjusted according to control result), it is real
Existing closed-loop control.
As further technical solution, the step of obtaining identification result are as follows: by the real part of complex mixing result be denoted as U1,
Imaginary part is denoted as U2, and U1 is added to obtain U3 with U2, subtracts each other U1 and U2 to obtain U4；The symbol of the symbol of U1 and U3 are subjected to exclusive or
Result and the symbol of U2 and the symbol of U4 carry out the result of exclusive or and carry out exclusive or again and obtain identification result.
As further technical solution, the loop filter includes frequency locking ring loop filter and cycle of phase-locked loop filter
Wave device first determines whether is frequency that frequency locking ring loop filter exports after adjusting control parameter after obtaining identification result
Less than threshold value: if so, cycle of phase-locked loop filter adjusts control parameter according to control result and exports control result, can be changed
Digital controlled oscillator is according to control result adjustment phase place control word；If it is not, then can be changed digital controlled oscillator according to frequency locking ring loop filtering
The control result of device output adjusts frequency control word.
As further technical solution, the frequency locking ring loop filter is that first-order loop filter or second-order loop are filtered
Wave device or third order PLL path filter.
As further technical solution, the cycle of phase-locked loop filter is that first-order loop filter or second-order loop are filtered
Wave device or third order PLL path filter.
Compared with prior art, the main beneficial effect of the present invention and advantage are as follows:
1, optimizing structure design saves hardware resource
The present invention optimizes Digital Down Convert part by tectonic knot function, avoids making for low-pass filter
With；For the complexity of frequency discrimination algorithm and phase demodulation algorithm diversity and realization, frequency discrimination algorithm and phase demodulation algorithm are optimized, it will
It is combined into one, and saves a large amount of hardware resource；Loop passes through the control of frequency-tracking thresholding, so that frequency locking ring and phaselocked loop
It does not work at the same time.These optimization designs to loop structure, all greatly save hardware resource.
2, computation complexity is low, is easy to Project Realization
The identification algorithm of discriminator is carried out frequency discrimination and phase demodulation using the mode of symbol exclusive or by the present invention, is avoided traditional
The operation of the various trigonometric functions of frequency discrimination and phase demodulation algorithm, is easy to Project Realization.
3, following range is wide, fast convergence rate, and loop stability is high
The present invention realizes carrier track using frequency locking ring and the tracing mode of phaselocked loop, so that system has the excellent of the two
Point not only ensure that the dynamic range of tracking frequency but also ensure the stability of tracking phase；The present invention is to carrier tracking loop
Optimization design makes system save a large amount of hardware resource in Project Realization and improves arithmetic speed, so that the receipts of loop
Hold back speed quickly.
4, have a wide range of application, engineering use value is high
Design and implementation method of the invention uses this modulation primarily directed to QPSK modulation system, therefore nearly all
The present invention can be used in the system of mode, and restrictive condition is few, function admirable, it is easy to accomplish, there is very strong Practical Project to answer
It, from now on can further genralrlization use with value.
Detailed description of the invention
Fig. 1 is that FLL assists PLL carrier tracking loop block diagram；
Fig. 2 is that FLL of the invention adds PLL carrier tracking loop block diagram；
Fig. 3 is that FLL of the invention adds PLL carrier tracking loop FPGA realization figure；
Fig. 4 is carrier tracking loop work flow diagram of the invention；
Fig. 5 is that carrier tracking loop of the invention tracks process simulation figure；
Fig. 6 is carrier tracking loop demodulating process analogous diagram of the invention；
Fig. 7 is that carrier tracking loop of the invention demodulates planisphere.
Specific embodiment
The present invention is described in detail with specific embodiment below in conjunction with the accompanying drawings.
Embodiment
The QPSK modulation system most commonly used for Telemetry System of UAV, carrier wave tracing method have very much, property
Can also there be very big difference.The present invention is mainly to add PLL carrier tracking loop to optimize FLL from the angle of practical engineering application to set
Meter, as shown in Figure 2 and Figure 3, the present invention first optimizes Digital Down Convert part in loop, passes through tectonic knot letter
Number (i.e. complex function) avoids the use of low-pass filter, reduces operand, saves hardware resource, after Digital Down Convert
I, Q two paths of data tectonic knot signal s (t), it is and defeated then by the local quadrature carrier also tectonic knot signal of NCO output
Enter signal s (t) and realize complex multiplication, real part data and imaginary data is taken to carry out subsequent loop operation respectively later.Then right
Frequency discrimination algorithm and phase demodulation algorithm are optimized in loop, it is contemplated that the complexity of frequency discrimination algorithm and phase demodulation algorithm diversity and realization
Property, no longer exclusive use frequency discrimination algorithm and phase demodulation algorithm, but be combined into one, and to be easy to Project Realization symbol different for use
Or mode carry out frequency discrimination and phase demodulation, reduce the operation of trigonometric function, not only saved hardware resource, also improve operation speed
Degree, and then improve the carrier track speed of loop.
The workflow step of carrier tracking loop of the invention as shown in figure 4, are as follows:
1, the intermediate-freuqncy signal Digital Down Convert for receiving Telemetry System of UAV is to quasi- base band, by I, Q two paths of data structure
Make analytical function I (k)+jQ (k) (i.e. complex function).
2, the orthogonal local trace carrier wave that variable NCO (digital controlled oscillator) generates is also configured as corresponding plural form,
3, the measurement and control signal received and local trace carrier wave are subjected to complex mixing (i.e. complex multiplication).
4, the result sub-argument after complex mixing is gone out into real and imaginary parts, through addition, subtract each other etc. operations respectively obtain U1,
U2, U3, U4 take the symbol of U1, U2, U3, U4 to carry out xor operation, the output result as discriminator respectively.Exporting result is 1
Or 0.
The step of obtaining identification result are as follows: the real part of complex mixing result is denoted as U1, imaginary part is denoted as U2, by U1 and U2 phase
Add to obtain U3, subtracts each other U1 and U2 to obtain U4；The symbol of the symbol of U1 and U3 are carried out to the result of exclusive or and the symbol and U4 of U2
Symbol carry out the result of exclusive or and carry out exclusive or again and obtain identification result.
5, loop filter adjusts control parameter according to identification result: when identification result is 1, corresponding control parameter is carried out
Inversion operation (i.e. control parameter is negative), when identification result is 0, then corresponding control parameter do not need inversion operation (i.e.
Control parameter is positive).
6, the control result that loop filter exports is sent to variable numerical control to vibrate, can be changed digital controlled oscillator according to control
As a result frequency control word and phase control words are adjusted, to change the frequency and phase of local quadrature carrier, return step 2 is real
Existing closed-loop control.
Loop filter includes frequency locking ring loop filter and cycle of phase-locked loop filter, and loop filter 1 is frequency locking ring
Loop filter, loop filter 2 are cycle of phase-locked loop filter.After obtaining identification result, frequency locking ring loop is first determined whether
Whether the frequency that filter exports after adjusting control parameter is less than threshold value: if so, cycle of phase-locked loop filter is according to control
Result processed adjusts control parameter and exports control result, can be changed digital controlled oscillator according to control result adjustment phase place control word；If
It is no, then it can be changed digital controlled oscillator according to the control result that frequency locking ring loop filter exports and adjust frequency control word.Threshold value is
It is manually set according to the actual situation.
Wherein, first-order loop filter or second-order loop filter or the filter of third order PLL road can be used in frequency locking ring loop filter
Wave device；First-order loop filter or second-order loop filter or third order PLL path filter can also be used in cycle of phase-locked loop filter.
Second order filter is all used in the present embodiment, filter each so only with two parameters are adjusted, has combined system realization
Complexity and algorithm performance.
According to above-mentioned method flow, use programmable logic device (FPGA) for the realization platform of digitized processing, such as Fig. 3
It is shown, Project Realization is carried out to the carrier tracking loop after optimization.
The carrier tracking loop after optimization is emulated using ModelSim simulation software, as a result as shown in Figure 5.From Fig. 5
In as can be seen that before before 0.15ms, frequency locking ring plays a major role, and is in a short period of time reduced to the frequency deviation of input signal
In the operating frequency range of phaselocked loop.Start phaselocked loop after 0.15ms, restrained using phase-locked loop after 0.1ms, in steady
State is determined, so that it is synchronous with phase to complete demodulation carrier frequency.Seen from the simulation results, the Digital Costas Loop table after optimization
Good carrier frequency and Phase Tracking performance are revealed.
Received UAV TT & C's signal is demodulated using the carrier tracking loop after optimization design, the result after demodulation
As shown in Figure 6.
From fig. 6 it can be seen that there is not aliased distortion and distortion in demodulator output baseband waveform, I, Q with modulation
The exact matching of two-way base band data, demodulation are completely correct.Corresponding demodulation planisphere is as shown in Figure 7.From the result of Project Realization
As can be seen that designed carrier tracking loop complies fully with the requirement of engineering.
By the Project Realization of traditional scheme and prioritization scheme, the present invention compared the two and use FPGA hardware resource feelings
Condition, as shown in table 1.By table 1 it can be seen that the scheme digital demodulation processing entirety after optimization can reduce by 10% or more resource,
Capable of reducing using to Block RAM 9%, 20% hardware resource can be reduced to the use of multiplier.The program is biggish to be reduced
Operand improves the utilization rate of FPGA hardware resource.
1 FPGA hardware resource comparison table of table
The foregoing is merely illustrative of the preferred embodiments of the present invention, is not intended to limit the invention, it is noted that all
Made any modifications, equivalent replacements, and improvements etc. within the spirit and principles in the present invention should be included in guarantor of the invention
Within the scope of shield.
Claims (4)
1. a kind of high dynamic UAV TT & C signal carrier tracking method, which is characterized in that the method comprising the steps of:
1) intermediate-freuqncy signal is formed by I, Q two paths of data tectonic knot function I (k)+jQ (k) through Digital Down Convert, will can be changed
The orthogonal local trace carrier wave that digital controlled oscillator generates constructs plural form
2) by I (k)+jQ (k) withCarry out complex mixing；
3) identification result is calculated using the real and imaginary parts of complex mixing result；The step of obtaining identification result are as follows: will answer
The real part of number mixing results is denoted as U1, imaginary part is denoted as U2, and U1 is added to obtain U3 with U2, subtracts each other U1 and U2 to obtain U4；By U1
Symbol and U3 symbol carry out exclusive or result and U2 symbol and U4 symbol carry out exclusive or result carry out exclusive or again
Obtain identification result；
4) loop filter adjusts control parameter according to identification result, and control result is sent to variable digital controlled oscillator；
5) can be changed digital controlled oscillator and frequency control word and phase control words, return step 1 adjusted according to control result), realization is closed
Ring control.
2. a kind of high dynamic UAV TT & C signal carrier tracking method according to claim 1, which is characterized in that described
Loop filter includes frequency locking ring loop filter and cycle of phase-locked loop filter, after obtaining identification result, first determines whether to lock
Whether the frequency that frequency ring loop filter exports after adjusting control parameter is less than threshold value: if so, frequency locking ring loop filtering
The control parameter of device is set as 0, and cycle of phase-locked loop filter adjusts control parameter according to control result and exports control result, can
Become digital controlled oscillator according to control result adjustment phase place control word；If it is not, the then control parameter setting of cycle of phase-locked loop filter
It is 0, variable digital controlled oscillator adjusts frequency control word according to the control result that frequency locking ring loop filter exports.
3. a kind of high dynamic UAV TT & C signal carrier tracking method according to claim 2, which is characterized in that frequency locking
Ring loop filter is first-order loop filter or second-order loop filter or third order PLL path filter.
4. a kind of high dynamic UAV TT & C signal carrier tracking method according to claim 2, which is characterized in that locking phase
Ring loop filter is first-order loop filter or second-order loop filter or third order PLL path filter.
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| CN109714047A (en) * | 2018-12-17 | 2019-05-03 | 上海航天电子有限公司 | A method of realizing the frequency locking track loop gain of simple Larger Dynamic |
| CN113093238B (en) * | 2021-03-25 | 2024-01-30 | 中国人民解放军国防科技大学 | Carrier wave numerical control oscillator, optimization method thereof and navigation receiver |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101975957A (en) * | 2010-09-21 | 2011-02-16 | 北京航空航天大学 | Fuzzy control-based high-dynamic GPS receiver carrier tracking loop |
| CN102621563A (en) * | 2012-03-20 | 2012-08-01 | 东南大学 | GPS (global positioning system) software receiver signal tracking method based on FPGA (field programmable gate array) and system of GPS software receiver signal tracking method |
| CN104215981A (en) * | 2014-08-28 | 2014-12-17 | 四川九洲电器集团有限责任公司 | Adaptive tracking method for receiver in high-dynamic environment |
-
2016
- 2016-12-22 CN CN201611195523.1A patent/CN107070832B/en active Active
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101975957A (en) * | 2010-09-21 | 2011-02-16 | 北京航空航天大学 | Fuzzy control-based high-dynamic GPS receiver carrier tracking loop |
| CN102621563A (en) * | 2012-03-20 | 2012-08-01 | 东南大学 | GPS (global positioning system) software receiver signal tracking method based on FPGA (field programmable gate array) and system of GPS software receiver signal tracking method |
| CN104215981A (en) * | 2014-08-28 | 2014-12-17 | 四川九洲电器集团有限责任公司 | Adaptive tracking method for receiver in high-dynamic environment |
Non-Patent Citations (3)
| Title |
|---|
| "High dynamic carrier tracking technology based on Kalman Filter";Wu Wenyu;《IET International Radar Conference 2015》;20160421;全文 * |
| "动态环境下基于FLL/PLL相结合的载波跟踪";陈晓鹏;《弹箭与制导学报》;20041230;全文 * |
| "基于FLL/PLL相结合的载波跟踪在导航接收机中的应用";沈锋;《中国航海》;20040630;全文 * |
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