阅读说明：本技术 一种基于信道模拟器的三频信标接收机电离层tec计算方法 (Ionized layer TEC calculation method of tri-band beacon receiver based on channel simulator ) 是由 於晓 郭敏军 陈亮 刘钝 刘少林 张发祥 王妍 于 2021-08-17 设计创作，主要内容包括：本发明公开了一种基于信道模拟器的三频信标接收机电离层TEC计算方法,包括如下步骤：步骤1,读取连接信道模拟器的三频信标接收机的输出文件,得到三频点信号的同相分量、相位值等：步骤2,对信号相位进行修正：步骤3,对修正后的相位序列进行连接,得到连续的相位曲线；步骤4,将连接后的连续相位,转化为相对TEC序列：步骤5,将相对TEC序列、卫星位置、观测的起始时间、接收机位置存成文件,用作星-地链路三频信标台链电离层CT算法验证的输入。本发明所公开的计算方法,用于从三频信标接收机输出的相干信标信号I、Q分量的连续序列出发,计算得到接收机上空相对TEC的时间序列,为基于低轨航天器的星载三频信标测量系统的设计和应用奠定了基础。(The invention discloses a channel simulator-based method for calculating an ionized layer TEC (thermoelectric cooler) of a tri-band beacon receiver, which comprises the following steps of: step 1, reading an output file of a tri-frequency beacon receiver connected with a channel simulator to obtain an in-phase component, a phase value and the like of a tri-frequency point signal: and step 2, correcting the signal phase: step 3, connecting the corrected phase sequences to obtain a continuous phase curve; and 4, converting the connected continuous phase into a relative TEC sequence: and 5, storing the relative TEC sequence, the satellite position, the observation starting time and the receiver position into a file, and using the file as the input of the ionosphere CT algorithm verification of the satellite-ground link three-frequency beacon chain. The calculation method disclosed by the invention is used for calculating the time sequence of the relative TEC in the sky of the receiver from the continuous sequence of the I, Q components of the coherent beacon signal output by the three-frequency beacon receiver, and lays a foundation for the design and application of a low-orbit spacecraft-based satellite-borne three-frequency beacon measurement system.)

1. A channel simulator-based ionized layer TEC calculation method for a tri-band beacon receiver is characterized by comprising the following steps:

step 1, reading an output file of a tri-frequency beacon receiver connected with a channel simulator to obtain an in-phase component I and an orthogonal component Q of a tri-frequency point signal, and calculating to obtain a power P and a phase value phi of the signal:

P＝10×lg(I²+Q²) (1)

Φ＝tan^-1(Q/I) (2)

and step 2, correcting the signal phase:

according to a phase noise background coefficient provided by a receiver manufacturer, phase drift is removed from a measured phase of the receiver;

and 3, the phase value of the receiver obtained in the step is always between-pi and pi, when the measured phase value is lower than-pi, the phase jumps to pi to start recording, and when the measured phase value is higher than pi, the phase jumps to-pi to start recording, and the +/-pi in the recording is overturned to carry out phase connection processing to form a continuous phase data curve, wherein the step is as follows:

the initial value of each parameter is set to the formula (3):

Φ_c(t)＝0,t＝1,k＝0(t∈I) (3)

wherein phi_cRepresenting the initial phase value, t the time series value, k the whole cycle value, and processing as follows until all data are connected:

step 31, differencing the corrected phase data:

Δ＝Φ(t+1)-Φ(t)

wherein t +1 and t correspond to different times, and phi is the phase value calculated in the step 2;

step 32, taking a threshold value D from-pi to pi, judging the number of + -pi flips of data during phase connection, wherein the criterion is as the following formula (4):

where Δ is the differential phase value obtained in step 31,

step 33, concatenate the original phases according to equation (5):

Φ'_c(t)＝Φ(t)+2π×k(t) (5)

Φ′_cfor the phase sequence after connection, after connection is completed, processing is performed according to the formulas (6) and (7):

Z＝min(Φ'_c(t)) (6)

Φ_c(t)＝Φ'_c(t)+|Z| (7)

z is the minimum phase value after phase connection;

and 4, converting the connected continuous phase into a relative TEC sequence:

the connected phase is in direct proportion to the relative TEC of the ionized layer, and the relative TEC value can be obtained by multiplying the phase by a proportional constant;

and 5, storing the relative TEC sequence, the satellite position, the observation starting time and the receiver position into a file, and using the file as the input of the ionosphere CT algorithm verification of the satellite-ground link three-frequency beacon chain.

2. The channel simulator-based triple-band beacon receiver ionosphere TEC calculation method of claim 1, wherein: step 1, adding a large attenuation at the end of a signal attenuation file input into a channel simulator, and using the attenuation as a mark for ending a simulation scene.

3. The channel simulator-based triple-band beacon receiver ionosphere TEC calculation method of claim 1, wherein: in the VHF, UHF and L three-frequency-point signals in the step 1, only the phases of the VHF frequency point and the L frequency point can be used for calculating the ionized layer TEC.

4. The channel simulator-based triple-band beacon receiver ionosphere TEC calculation method of claim 1, wherein: the threshold value D of step 32 is taken to be 5 π/3, corresponding to 300.

5. The channel simulator-based triple-band beacon receiver ionosphere TEC calculation method of claim 1, wherein: the proportionality constant of step 4 is 0.020677.

Technical Field

The invention belongs to the field of ionosphere TEC calculation, and particularly relates to a channel simulator-based ionosphere TEC calculation method for a tri-band beacon receiver, which is used for calculating the ionosphere TEC of the tri-band beacon receiver connected with a channel simulator, and the calculation result can be used as the input of satellite-ground link tri-band beacon ionosphere CT algorithm verification.

Background

The ionosphere TEC is defined as an integral value of electron density along a signal propagation path per unit cross section, and is an ionosphere characteristic parameter closely related to radio wave propagation characteristics.

The ionosphere TEC measurement technology based on the satellite beacon is mainly based on Doppler frequency shift, additional time delay or Faraday rotation and other effects generated when a satellite beacon signal propagates through an ionosphere channel. The differential Doppler technology is based on the dispersion effect of the ionized layer, the influence of satellite motion is eliminated by the difference of Doppler frequency shifts of dual-frequency (or multi-frequency) coherent signals, and the additional frequency shift related to the ionized layer TEC is reserved and is converted to obtain the ionized layer TEC.

Early typical beacons available for ionosphere TEC detection were carried on the Navy naval meridian Satellite Navigation System (NNSS). A dual-frequency beacon transmitter carried by an NNSS satellite transmits dual-frequency coherent signals with carrier frequencies of 150MHz and 400MHz, a receiver arranged on the ground receives the satellite beacon signals, and the ionosphere TEC measurement can be realized by utilizing a differential Doppler frequency shift technology. Subsequently, the united states, russia, etc. have transmitted successively OSCAR, RADCAL, DMSP F15, COSMOS, etc. satellites, all of which carry coherent beacon transmitters. Since the 20 th century, the united states transmitted the constellation of cosinc satellites, with 6 small satellites carrying a coherent beacon transmitter, a masker receiver, and a small photometer. Wherein the coherent beacon transmitter is used as a scintillation measurement of the ionosphere TEC and coherent frequency point signals along the satellite-ground link. Due to the success of the cosinc satellite program, the united states transmitted 6 again cosic-II low-orbit equatorial moonlets in 2019, with the main payload including a triple-band beacon transmitter, a masker receiver, and an ion drift rate meter.

The three-frequency beacon measuring system consists of a satellite-borne subsystem and a ground subsystem, wherein a three-frequency beacon transmitter of the satellite-borne subsystem transmits a group of phase-coherent VHF, UHF and L frequency band signals to the ground, and large-range rapid scanning of an ionosphere is realized along with the movement of a satellite. A tri-frequency beacon receiver of the ground subsystem tracks and receives tri-frequency coherent signals transmitted by a satellite through an antenna, changes of phases, amplitudes and the like of the tri-frequency signals when the tri-frequency signals pass through an ionosphere channel are obtained through processing, and the ionosphere TEC of a satellite-ground link is obtained through differential Doppler calculation.

Compared with the traditional foundation monitoring technology, the main advantages of the measurement of the tri-band beacon ionized layer TEC are as follows: global scope measurements are performed along satellite motion, and top ionosphere TEC information above F2 can be included, low-orbit satellite motion is fast so that ionosphere static assumptions hold, horizontal resolution is high, and the like. In recent years, China also accelerates the research on satellite-borne triple-frequency beacon measurement technology, the first satellite-borne coherent beacon load is successfully carried on a seismic electromagnetic monitoring test satellite, a group of coherent carrier signals are emitted, and ionosphere TEC measurement can be realized.

A group of receiver station chains are distributed on the ground along the meridian direction, meanwhile, coherent beacon signals transmitted by a satellite-borne tri-frequency beacon transmitter are received, and the ionosphere TEC with a large number of crossed observation paths over a plurality of stations can be obtained through combined processing. Based on the ionosphere tomography (CIT) technology, the method realizes the reconstruction of the electron density of the ionosphere in a large range, and can be used for early warning of earthquake ionosphere precursors or monitoring of space weather events.

Disclosure of Invention

The invention provides a method for calculating an ionized layer TEC (thermoelectric cooler) of a triple-frequency beacon receiver based on a channel simulator, which starts from a continuous sequence of I, Q components of a multi-frequency point coherent signal output by the triple-frequency beacon receiver to calculate a relative TEC time sequence over an observation station, and can be used as an input for ionosphere CT (computed tomography) algorithm verification of a satellite-ground link triple-frequency beacon and also used for calculating the ionized layer TEC of the triple-frequency beacon receiver connected with the channel simulator.

The invention adopts the following technical scheme:

the improvement of a method for calculating the ionosphere TEC of a tri-band beacon receiver based on a channel simulator, which comprises the following steps:

step 1, reading an output file of a tri-frequency beacon receiver connected with a channel simulator to obtain an in-phase component I and an orthogonal component Q of a tri-frequency point signal, and calculating to obtain a power P and a phase value phi of the signal:

P＝10×lg(I²+Q²) (1)

Φ＝tan^-1(Q/I) (2)

and step 2, correcting the signal phase:

according to a phase noise background coefficient provided by a receiver manufacturer, phase drift is removed from a measured phase of the receiver;

step 3, connecting the corrected phase sequences to obtain a continuous phase curve;

the phase value of the receiver obtained by the steps is always between-pi and pi, when the measured phase value is lower than-pi, the phase jumps to pi to start recording, and when the measured phase value is higher than pi, the phase jumps to-pi to start recording, and the +/-pi in the recording is overturned to carry out phase connection processing to form a continuous phase data curve, and the steps are as follows:

the initial value of each parameter is set to the formula (3):

Φ_c(t)＝0,t＝1,k＝0(t∈I) (3)

wherein phi_cRepresenting the initial phase value, t the time series value, k the whole cycle value, and processing as follows until all data are connected:

step 31, differencing the corrected phase data:

Δ＝Φ(t+1)-Φ(t)

wherein t +1 and t correspond to different times, and phi is the phase value calculated in the step 2;

step 32, taking a threshold value D from-pi to pi, judging the number of + -pi flips of data during phase connection, wherein the criterion is as the following formula (4):

where Δ is the differential phase value obtained in step 31,

step 33, concatenate the original phases according to equation (5):

Φ'_c(t)＝Φ(t)+2π×k(t) (5)

Φ′_cfor the phase sequence after connection, after connection is completed, processing is performed according to the formulas (6) and (7):

Z＝min(Φ'_c(t)) (6)

Φ_c(t)＝Φ'_c(t)+|Z| (7)

z is the minimum phase value after phase connection;

and 4, converting the connected continuous phase into a relative TEC sequence:

the connected phase is in direct proportion to the relative TEC of the ionized layer, and the relative TEC value can be obtained by multiplying the phase by a proportional constant;

and 5, storing the relative TEC sequence, the satellite position, the observation starting time and the receiver position into a file, and using the file as the input of the ionosphere CT algorithm verification of the satellite-ground link three-frequency beacon chain.

Further, step 1 adds a large attenuation at the end of the signal attenuation file input to the channel simulator, as an indication of the end of the simulation scene.

Further, in the VHF, UHF and L three-frequency point signals in step 1, only the phase of the VHF frequency point and the phase of the L frequency point can be used for calculating the ionosphere TEC.

Further, the threshold D of step 32 is taken to be 5 π/3, corresponding to 300.

Further, the proportionality constant of step 4 is 0.020677.

The invention has the beneficial effects that:

the calculation method disclosed by the invention is used for calculating and obtaining the time sequence of the relative TEC in the sky of the receiver from the continuous sequence of the I, Q components of the coherent beacon signals output by the three-frequency beacon receiver, generating an input file for ionosphere CT algorithm verification of the satellite-ground link three-frequency beacon station chain, using the input file as simulation verification of the ionosphere CT algorithm of the three-frequency beacon, and laying a foundation for the design and application of a satellite-borne three-frequency beacon measurement system based on a low-orbit spacecraft.

Drawings

FIG. 1 is a schematic flow chart of a disclosed calculation method;

FIG. 2 is a signal power curve of a triple-frequency point calculated in example 1;

FIG. 3 is the phase values of the triple-frequency point signal calculated in example 1;

FIG. 4 is a graph showing the results of the phase correction of the VHF frequency points in example 1;

FIG. 5 is a graph showing the results of connecting the phases of the VHF frequency points in example 1;

FIG. 6 is a graph of relative TEC results for phase inversion by connected VHF frequency bins in example 1;

FIG. 7 is a signal power curve of a triple-frequency point calculated in example 2;

FIG. 8 is the phase values of the triple-frequency point signal calculated in example 2;

FIG. 9 is a graph showing the results of phase correction of the VHF frequency points in example 2;

FIG. 10 is a graph showing the results of connecting the phases of the VHF frequency points in example 2;

fig. 11 is a graph of relative TEC results from phase inversion at the VHF frequency bins after concatenation in example 2.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be described in further detail below with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

As shown in fig. 1, the invention discloses a method for calculating an ionosphere TEC of a triple-band beacon receiver based on a channel simulator, which comprises the following steps:

step 1, reading an output file of a tri-frequency beacon receiver connected with a channel simulator to obtain an in-phase component I and an orthogonal component Q of VHF, UHF and L frequency point signals, and calculating to obtain a power P and a phase value phi of the tri-frequency point signals:

P＝10×lg(I²+Q²) (1)

Φ＝tan^-1(Q/I) (2)

since the output file of the receiver connected to the simulator has no time information, a large attenuation is added at the end of the signal attenuation file of the input channel simulator as a sign of the end of the simulation scene. The flag is found from the signal power curve and the following data is discarded.

And step 2, correcting the signal phase:

the receiver has a slow drift of the phase at the time of actual measurement due to thermal noise or the like. And calibrating the phase measurement noise of the receiver in a laboratory, and storing the background coefficient of the phase noise into a file. The coefficients may also be provided by the receiver manufacturer. After reading, the measurement phases are removed from the receiver.

Step 3, connecting the corrected phase sequences to obtain a continuous phase curve;

the phase value of the receiver obtained by the steps is always between-pi and pi, when the measured phase value is lower than-pi, the phase jumps to pi to start recording, and when the measured phase value is higher than pi, the phase jumps to-pi to start recording, and the phase is continuous, so that the phase connection processing must be carried out by inverting the + -pi in the recording to form a continuous phase data curve.

And 4, converting the connected continuous phase into a relative TEC sequence:

the phase after connection is in direct proportion to the relative TEC of the ionized layer, and the relative TEC value can be obtained by multiplying the phase after connection by a proportional constant; the proportionality constant is related to the frequencies of the two coherent signals of the differential doppler calculation.

And 5, storing the relative TEC sequence, the satellite position, the observation starting time, the receiver position and the like into files, and using the files as input for verifying the ionosphere CT algorithm of the satellite-ground link three-frequency beacon chain.

The embodiment 1 discloses a method for calculating an ionosphere TEC of a triple-band beacon receiver based on a channel simulator, which includes the following steps:

step 1, reading an output file of a tri-frequency beacon receiver connected with a channel simulator to obtain an in-phase component I and an orthogonal component Q of a tri-frequency point signal, and calculating to obtain a power P and a phase value phi of the signal:

the initial measurement time of the measurement scenario input to the channel simulator is 2015 at 1, 7, 6, with the receiver at the opponent's home (26.92 ° N, 102.93 ° E). The output file of the receiver connected with the channel simulator records information such as I, Q components when coherent beacon signals (VHF, UHF and L frequency points) reach the ground through ionosphere propagation.

From the I, Q component of the coherent beacon signal, the signal power value is calculated by equation (1):

P＝10×lg(I²+Q²) (1)

the calculated signal power curves of the three frequency points are shown in fig. 2, and are VHF, UHF and L frequency points in sequence from top to bottom. It can be seen that the signal power of the triple-frequency point is relatively clean before 27000 multiple points and is close to a straight line. After 27000 a lot there is a sudden large drop and then the undulations are large, close to the noise. This is because the output file of the receiver connected to the simulator does not contain time information, so a large attenuation is added at the end of the signal attenuation file of the input channel simulator as a sign of the end of the simulated scene. And finding out a mark of the beginning of the great power value attenuation from the signal power curve, and discarding the following data.

From the I, Q component of the coherent beacon signal, the phase of the signal is calculated by equation (2):

Φ＝tan^-1(Q/I) (2)

the phase values of the calculated three-frequency-point signals are shown in fig. 3 and are VHF, UHF and L frequency points from top to bottom in sequence. It can be seen that the phase values of the VHF and L frequency points are always between-pi and pi, when the measured phase value is lower than-pi, the phase jumps to pi to start recording, and when the measured phase value is higher than pi, the phase jumps to-pi to start recording. But the phase of the UHF frequency point is always near zero value, and the fluctuation is very small. This is because the intermediate frequency processing unit in the triple-band beacon receiver performs differential processing on the data of the VHF, UHF, and L frequency points, and outputs I, Q information obtained by differentiating the corresponding frequency point from the UHF frequency point. Therefore, only the phases of the VHF and L frequency points are available for calculation of the ionosphere TEC. The latter example takes the phase of the VHF bins for calculation.

And step 2, correcting the signal phase:

the receiver has a slow drift of the phase at the time of actual measurement due to thermal noise or the like. The calibration value of the phase noise background coefficient provided by the receiver manufacturer is read and eliminated from the measurement phase of the receiver. Fig. 4 shows the result of phase correction of the VHF frequency point.

Step 3, connecting the corrected phase sequences to obtain a continuous phase curve;

the receiver phase obtained from step 2 has + -pi flip, and the phase itself is continuous, so the + -pi flip in the record is processed by phase connection to form a continuous phase data curve. The initial value of each parameter is set to the formula (3):

Φ_c(t)＝0,t＝1,k＝0(t∈I) (3)

wherein phi_cRepresenting the initial phase value, t the time series value, k the whole cycle value, and processing as follows until all data are connected:

step 31, differencing the corrected phase data:

Δ＝Φ(t+1)-Φ(t)

wherein t +1 and t correspond to different times, and phi is the phase value calculated in the step 2;

step 32, taking a proper threshold value D from-pi to judge the phase and connect the data, judging the number of + -pi flips of the data when the phase is connected, wherein the criterion is the formula (4):

where Δ is the differential phase value obtained in step 31,

step 33, concatenate the original phases according to equation (5):

Φ'_c(t)＝Φ(t)+2π×k(t) (5)

Φ′_cfor the phase sequence after connection, after connection is completed, processing is performed according to the formulas (6) and (7):

Z＝min(Φ'_c(t)) (6)

Φ_c(t)＝Φ'_c(t)+|Z| (7)

z is the minimum phase value after phase connection, where the threshold value D is taken to be 5 pi/3, corresponding to 300 °. Fig. 5 shows the result of connecting the phases of the VHF frequency points.

And 4, converting the connected continuous phase into a relative TEC sequence:

since the phase after connection is proportional to the relative TEC of the ionosphere, the relative TEC value can be obtained by multiplying it by a proportionality constant. The proportionality constant is related to the frequency of the UHF and VHF bins, and is taken as 0.020677. Fig. 6 shows the relative TEC results phase-inverted from the VHF bins after concatenation.

And 5, storing the relative TEC sequence, the satellite position, the observation starting time, the receiver position and the like into files, and using the files as input for verifying the ionosphere CT algorithm of the satellite-ground link three-frequency beacon chain.

Embodiment 2, this embodiment discloses a method for calculating an ionosphere TEC of a triple-band beacon receiver based on a channel simulator, including the following steps:

step 1, reading an output file of a tri-frequency beacon receiver connected with a channel simulator, and calculating signal power and a phase value.

The initial measurement time of the measurement scenario input to the channel simulator was 2015 at 1, 7, and 6, with the receiver at horse edge (28.84 ° N, 103.55 ° E). The output file of the receiver connected with the channel simulator records information such as I, Q components when coherent beacon signals (VHF, UHF and L frequency points) reach the ground through ionosphere propagation. The signal power curve of the three frequency points calculated from the I, Q component of the coherent beacon signal and the above equation (1) is shown in fig. 7, and the frequency points are VHF, UHF and L in sequence from top to bottom. It can be seen that the signal power of the triple-frequency point is relatively clean before 26800 points, and is close to a straight line. After 26800 a lot there is a sudden large drop and then the undulations are large, close to the noise. And discarding the data after the power value is greatly attenuated.

The phase values of the triple-frequency-point signal calculated by the I, Q component of the coherent beacon signal and the above equation (2) are VHF, UHF and L frequency points in sequence from top to bottom as shown in fig. 8. It can be seen that the phase values of the VHF and L frequency points are always between-pi and pi, while the phase of the UHF frequency point is always near zero value and has little fluctuation. Therefore, only the phases of the VHF and L frequency points are available for calculation of the ionosphere TEC. The latter example takes the phase of the VHF bins for calculation.

And 2, reading a calibration value of the phase noise background coefficient provided by a receiver manufacturer, correcting the measured phase of the receiver, and obtaining a phase result of the VHF frequency point after correction as shown in FIG. 9.

And 3, connecting the corrected phase sequences, and taking the set phase overturning threshold value as 5 pi/3 (corresponding to 300 degrees). Fig. 10 shows the result of connecting the phases of the VHF frequency points.

And 4, multiplying the connected phase by a fixed constant 0.020677 to obtain a relative TEC sequence shown in FIG. 11.

And 5, storing the relative TEC sequence, the satellite position, the observation starting time, the receiver position and the like into files, and using the files as input for verifying the ionosphere CT algorithm of the satellite-ground link three-frequency beacon chain.