CN109740225A - A method of it calculates and assesses for broad-band TWT - Google Patents
A method of it calculates and assesses for broad-band TWT Download PDFInfo
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Abstract
The present invention discloses a kind of method for calculating assessment for broad-band TWT, applied to traveling wave tube model and Performance Evaluation field, aiming at the problem that traditional narrow model is difficult to the needs of meeting contemporary broadband travelling-wave tubes and wideband satellite communication application, the present invention is on the basis of traditional narrow nonlinear model, the relevant nonlinear model structure of pull-in frequency, while third order intermodulation is constructed using nonlinear organization；It completes to carry out broadband modeling to travelling-wave tubes, and modeling and parameter extraction are carried out to travelling-wave tubes using the function of cartesian coordinate form, travelling-wave tubes nonlinear model decompose by fourier series and spectrum analysis is carried out to it, improves the accuracy of characterization transmission characteristic and crosstalk relationship.
Description
Technical field
The invention belongs to traveling wave tube model and Performance Evaluation field, in particular to a kind of travelling-wave tubes non-linearity of power amplifier
The emulation technology of characteristic.
Background technique
With the development of satellite communication, its satellite business traffic is sharply increased, and needs that bandwidth is wider, spectrum efficiency is higher
Communication system, the modulation system (M-QAM etc.) of current some broadband digital transmission technologies and high spectrum utilization is used for satellite
Communication system.But have the characteristics that non-constant-envelope, broadband and peak-to-average ratio using the signal that these technologies are transmitted, when
Modulated signal is interfered adjacent by that will generate band and out-of-band distortion, output signal spectrum extension after nonlinear power amplifier
Adjacent Channel increases the communication system bit error rate.Therefore, bandwidth and the linearity of the modern satellite communications system to radio-frequency power amplifier
Propose very high requirement.Therefore, it is necessary to carry out performance calculating assessment to broad-band TWT, whether it is suitable for satellite communication.Separately
It on the one hand, is the rollback for reducing traveling wave tube power amplifier, to guarantee to improve its linearity in the case where the efficiency of travelling-wave tubes,
Need to linearize travelling-wave tubes using linearizer, thus be also required to model the linear properties of travelling-wave tubes in order to
The design of linearizer.
Traditional traveling wave tube model and Performance Evaluation use Saleh model or multinomial model, utilize power amplifier
Envelope trait extracts model and input-output characteristic and Model Matching gets up well.But Saleh model is narrowband model, when
The preceding requirement with the development of telecommunications to travelling-wave tubes bandwidth is more and more wider, and traditional narrow model is difficult to meet contemporary broadband row
The demand of wave duct and wideband satellite communication application, needs to develop the travelling-wave tubes characteristic model of frequency dependence.Simultaneously because it is not easy
Third order intermodulation is calculated especially to calculate with the third order intermodulation after linearizer cascade.When calculating third order intermodulation, series exhibition is utilized
It opens as polynomial computation third order intermodulation, then can bring error problem.And as multinomial series order increases, error is not
Tend to 0；It has a certain impact to precision.
Summary of the invention
In order to solve the above technical problems, the present invention proposes a kind of method for calculating assessment for broad-band TWT,
Frequency dependence extension is carried out on the basis of Saleh model, can emulate input and output amplitude/phase of broad-band TWT frequency dependence
Position characteristic, gain characteristic and third order intermodulation characteristic etc..
The technical solution adopted by the present invention are as follows: a method of it calculates and assesses for broad-band TWT, in traditional Saleh
On the basis of model, pull-in frequency continuous item filter characterizes the nonlinear frequency characteristic of travelling-wave tubes, the frequency dependence item
Filter includes same phase non-linear frequency property filter, Nonlinear Orthogonal frequency characteristic filter.The following steps are included:
S1, under the conditions of with interior different frequency, the input-output characteristic of testing broad-band travelling-wave tubes amplitude and phase.Establish row
Wave duct input-output characteristic model is fitted its curve to input-output characteristic using least variance method, establishes broad-band TWT frequency
The relevant input/output model of rate.
S2, according to travelling-wave tubes input-output characteristic model, construct traveling wave tube model cartesian coordinate form.Here traveling wave
Pipe input-output characteristic model specifically: pull-in frequency relevant parameter and original broad-band TWT with phase distortion frequency component/
Broad-band TWT quadrature distortion frequency component, be multiplied generates frequency correlation function to characterize non-linear frequency characteristic.
Traveling wave tube model in-phase component, traveling wave tube model quadrature component are constructed respectively；
S3, according to traveling wave tube model cartesian coordinate form, respectively to traveling wave tube model with mutually and Nonlinear Orthogonal component
Carry out third order intermodulation calculating.
S4, basis obtain final third order intermodulation component with the third order intermodulation calculated value of phase and quadrature component.
Beneficial effects of the present invention: the present invention is based on the travelling-wave tube amplifier ultra wide band line performance evaluations of telecommunication satellite application
Introducing frequency domain is tieed up and constructs travelling-wave tubes characteristic two dimensional model in traditional amplitude dimension with simulation study, and linearisation travelling-wave tubes characteristic=
F (incoming level, frequency), frequency domain filter is for characterizing the nonlinear frequency characteristic of travelling-wave tubes, so as to characterize travelling-wave tubes
Non-linear frequency domain characteristic；The relationship of assessment transmission characteristic and crosstalk is finally modeled and calculated to travelling-wave tubes；Simultaneously originally
Invention characterizes the accuracy of transmission characteristic and crosstalk relationship to improve, using the function of cartesian coordinate form to travelling-wave tubes
Modeling and parameter extraction are carried out, travelling-wave tubes nonlinear model is carried out by fourier series to decompose and carry out it frequency spectrum point
Analysis, calculation method of the invention consider frequency characteristic, improve its accuracy.
Detailed description of the invention
Fig. 1 is the cartesian coordinate form block diagram of tradition Saleh model；
Fig. 2 is the cartesian coordinate form block diagram of frequency dependence traveling wave tube amplifier nonlinearity model provided by the invention；
Fig. 3 is the detailed maps of Fig. 2；
Wherein, 11 be narrowband travelling-wave tubes with phase distortion component；12 be 90 degree of phase shifts；13 be narrowband travelling-wave tubes quadrature distortion point
Amount；21 be broad-band TWT with phase distortion frequency response filter；22 be broad-band TWT quadrature distortion frequency characteristic filter；
31 be broad-band TWT with phase non-linear frequency property filter；32 filter for broad-band TWT Nonlinear Orthogonal frequency characteristic
Device.
Specific embodiment
For convenient for those skilled in the art understand that technology contents of the invention, with reference to the accompanying drawing to the content of present invention into one
Step is illustrated.
The present embodiment is first illustrated narrowband travelling-wave tubes NONLINEAR CALCULATION process, is as shown in Figure 1 tradition Saleh mould
The cartesian coordinate form block diagram of type, when multicarrier cosine signalWhen inputting travelling-wave tubes, fmIt is carried for m-th
The input frequency of wave, Vm are the amplitudes of m-th of incoming carrier, and t is the time.Narrowband travelling-wave tubes can be indicated with phase distortion component 11
For P (r), narrowband travelling-wave tubes quadrature distortion component 13 can be expressed as Q (r), wherein
Travelling-wave tubes is respectively as follows: with phase and orthogonal signalling output
YI(t)=F (A) cos [θ (A)] cos (2 π f0+σ0)
YQ(t)=F (A) sin [θ (A)] cos (2 π f0+σ0)
Wherein, A indicates signal amplitude, and F (A) cos [θ (A)] and F (A) sin [θ (A)] are the unrelated amplitude non-linearities of frequency,
Therefore it is non-linear that the unrelated narrowband travelling-wave tubes of frequency can only be characterized, itself is used in middle subscript I/Q (In-phase/Quadrature)
In expression inphase/orthogonal.
It can be indicated with phase with Nonlinear Orthogonal by Bessel function are as follows:
Wherein, J1() is first kind first-order bessel function.2D is the dynamic range of surveyed input voltage, D indicate from
Zero arrives the absolute value value of maximum voltage.It is the coefficient of travelling-wave tubes inphase/orthogonal model, it can be non-thread by travelling-wave tubes
Property input/output signal envelope amplitude or phase nonlinear data digital simulation obtain.
Travelling-wave tubes output signal frequency component are as follows:
Amplitude output signal are as follows:
Wherein,
Wherein, αmThe order for indicating Bessel function, can be positive number, negative or zero；J|αi|() is a kind of | αi| rank shellfish
Sai Er function indicates influence of i-th of incoming carrier to output nonlinear；It is the order of output frequency component and is
Odd number,For export inphase/orthogonal component amplitude,It is model coefficient, can be obtained by Function Fitting.
For the characteristic for characterizing frequency dependence, as shown in Fig. 2, during broad-band TWT NONLINEAR CALCULATION, present invention introduces
Frequency dependence parameterWith it is originalBe multiplied and generates frequency correlation functionIt characterizes non-thread
Resistant frequency characteristic, frequency correlation functionIs defined as:
Wherein,It indicatesMiddle frequency independent parameter part,It indicatesMiddle frequency independent parameter part,It is the function of frequency f, product represents former nonlinear model.
As shown in figure 3, non-linear to the non-linear each single item of travelling-wave tubes are as follows:
Then method of the invention is by being added frequency dependence item filter in-phase componentAnd quadrature component
Characterize the nonlinear frequency characteristic of travelling-wave tubes.
Under wideband scenarios, travelling-wave tubes output signal frequency component is still is defined as: I, Q is respectively indicated with phase and quadrature component.
Travelling-wave tubes nonlinear output signal amplitude under the input stimulus of broadband are as follows:
Wherein,
Those of ordinary skill in the art will understand that the embodiments described herein, which is to help reader, understands this hair
Bright principle, it should be understood that protection scope of the present invention is not limited to such specific embodiments and embodiments.For ability
For the technical staff in domain, the invention may be variously modified and varied.All within the spirits and principles of the present invention, made
Any modification, equivalent substitution, improvement and etc. should be included within scope of the presently claimed invention.
Claims (6)
1. a kind of method for calculating assessment for broad-band TWT, which is characterized in that on the basis of traditional Saleh model,
Pull-in frequency continuous item filter characterizes the nonlinear frequency characteristic of travelling-wave tubes.
2. a kind of method for calculating assessment for broad-band TWT according to claim 1, which is characterized in that the frequency
Continuous item filter includes same phase non-linear frequency property filter, Nonlinear Orthogonal frequency characteristic filter.
3. a kind of method for calculating assessment for broad-band TWT according to claim 2, which is characterized in that use flute card
You carry out modeling and parameter extraction to travelling-wave tubes at coordinate form, obtain the width of the same phase of broad-band TWT output model, quadrature component
Degree is respectively as follows:
Wherein, αmIndicate the order of Bessel function, m=1,2 ..., M；It is a kind of | αi| rank Bessel function, i are indicated
I-th of incoming carrier；It is the order of output frequency component and is odd number,For broad-band TWT output
The amplitude of model in-phase component,For the amplitude of broad-band TWT output model quadrature component,For
Travelling-wave tubes output signal homophase frequency component,For travelling-wave tubes output signal quadrature frequency components,It is broadband
Travelling-wave tubes output model in-phase component coefficient,It is broad-band TWT output model quadrature component coefficient.
4. a kind of method for calculating assessment for broad-band TWT according to claim 3, which is characterized in that described It is got respectively by the non-linear input/output signal envelope amplitude of travelling-wave tubes, phase nonlinear data digital simulation.
5. a kind of method for the assessment of broad-band TWT NONLINEAR CALCULATION, feature according to claim 2,3 and 4 exist
According to travelling-wave tubes cartesian coordinate model form, respectively to line width band wave duct model with phase and quadrature component three rank friendships of progress
It adjusts and calculates.
6. a kind of method for calculating assessment for broad-band TWT according to claim 6, which is characterized in that according to traveling wave
Final third order intermodulation component is calculated in the third order intermodulation calculated result of tube model in-phase component and quadrature component.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111125897A (en) * | 2019-12-17 | 2020-05-08 | 电子科技大学 | Fast calculation method for noise power ratio NPR of traveling wave tube |
| CN112887007A (en) * | 2021-01-14 | 2021-06-01 | 航天科工空间工程发展有限公司 | Method for calculating overhead of multi-channel transparent repeater of communication satellite |
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| US6586883B1 (en) * | 2001-12-20 | 2003-07-01 | Lockheed Martin Corporation | Method and apparatus for detecting individual TWT helix current for multiple TWT loads |
| CN101159725A (en) * | 2007-08-10 | 2008-04-09 | 北京北广科数字广播电视技术有限公司 | Method of implementing polynomial based open loop digital baseband predistorter |
| CN102545796A (en) * | 2012-02-15 | 2012-07-04 | 电子科技大学 | Traveling wave tube linearizer |
| CN106453170A (en) * | 2016-09-27 | 2017-02-22 | 工业和信息化部电信研究院 | Signal nonlinear time-domain measurement and simulation method and application |
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Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6586883B1 (en) * | 2001-12-20 | 2003-07-01 | Lockheed Martin Corporation | Method and apparatus for detecting individual TWT helix current for multiple TWT loads |
| CN101159725A (en) * | 2007-08-10 | 2008-04-09 | 北京北广科数字广播电视技术有限公司 | Method of implementing polynomial based open loop digital baseband predistorter |
| CN102545796A (en) * | 2012-02-15 | 2012-07-04 | 电子科技大学 | Traveling wave tube linearizer |
| CN106453170A (en) * | 2016-09-27 | 2017-02-22 | 工业和信息化部电信研究院 | Signal nonlinear time-domain measurement and simulation method and application |
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Cited By (3)
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|---|---|---|---|---|
| CN111125897A (en) * | 2019-12-17 | 2020-05-08 | 电子科技大学 | Fast calculation method for noise power ratio NPR of traveling wave tube |
| CN111125897B (en) * | 2019-12-17 | 2023-03-03 | 电子科技大学 | Fast calculation method for noise power ratio NPR of traveling wave tube |
| CN112887007A (en) * | 2021-01-14 | 2021-06-01 | 航天科工空间工程发展有限公司 | Method for calculating overhead of multi-channel transparent repeater of communication satellite |
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