CN103793617A - Method for determining concentration of electrons of ionized layer - Google Patents

Abstract

The invention belongs to the technical field of space physics, and discloses a method for determining the concentration of electrons of an ionized layer. The method includes the steps that first, the concentration of electrons in the zenith direction is calculated through a double frequency code phase position observation value; second, the concentration of electrons in the zenith direction is calculated through a double frequency carrier phase position observation value; third, by establishing a regression equation, the concentration of the electrons of the ionized layer is solved. With the method, the calculating accuracy of the concentration of the electrons of the ionized layer is improved, and therefore the lag correction accuracy of the ionized layer of signals can be improved.

Description

A kind of ionospheric electron density is determined method

Technical field

The invention belongs to space physics technical field, relate to a kind of ionospheric electron density and determine method.

Background technology

At present in the technical field such as space flight measurement and control, communication and navigation, while relating to signal correction, need to calculate the ionospheric electron density of signal propagation path, conventionally adopt ionosphere single-layer model SLM (Single Layer Model) to calculate zenith direction ionospheric electron density VTEC.It is upper that in SLM supposition ionosphere, all electronics concentrate on the unlimited thin individual layer of a thickness (generally choosing height 350km), and complicated ionospheric structure is simplified greatly.

VTEC＝TEC.cosz′

In above formula, VTEC represents the ionospheric electron density of zenith direction, and TEC represents the total electron number in ionosphere, i.e. ionospheric electron density, and z ' is the zenith distance of the intersection point place sense of signal path and individual layer.In the practical engineering application such as space flight measurement and control, can the ionospheric electron density VTEC that calculate zenith direction will be equal to the calculating of ionospheric electron density by above formula thus.

Existing ionospheric model is that its precision is not high take the statistical nature of pediocratic Global Ionospheric electron concentration as Foundation, can not meet the needs that in Space TT&C, website VTEC calculates, especially in the solar activity phase.

Summary of the invention

A kind of definite ionospheric electron density method that provides precision higher is provided the object of the invention, to improve signal ionosphere delay computational accuracy.

For achieving the above object, ionospheric electron density provided by the invention is determined method, comprises the following steps:

Step 1, use dual-frequency code phase observations value are calculated zenith direction electron concentration VTEC ₁

VTEC ₁＝9.52437(P ₂-P ₁)·cosz′+σ ₁

Wherein, z ' is the zenith distance of signal path and individual layer intersection point place sense, P ₁be code phase observed reading, the P of the first frequency ₂be the code phase observed reading of the second frequency, σ ₁=-9.52437.cosz ' B, B represents ionosphere delay deviation poor of the code phase observed reading of two frequencies;

Step 2, use dual-frequency carrier observed reading are calculated zenith direction electron concentration VTEC ₂

VTEC ₂＝9.52437[λ ₁φ ₁-λ ₂φ ₂)+(λ ₁N ₁-λ ₂N ₂)]·cosz′+σ ₂

Wherein, λ ₁be carrier wavelength, the λ of the first frequency ₂be the carrier wavelength of the second frequency, φ ₁be the first frequency carrier phase observation data, φ ₂be the second frequency carrier phase observation data, N ₁be integer ambiguity, the N of the first frequency carrier wave ₂be the integer ambiguity of the second frequency carrier wave, σ ₂=9.52437cosz ' L _g, L _grepresent ionosphere delay deviation poor of the carrier phase observation data of two frequencies;

Step 3, determine Shen absciss layer electron concentration TEC

$\widehat{\mathrm{VTEC}}=a_0+a_1\mathrm{<figure-callout\; id="1"\; label="VTE\; C"\; filenames="HSA0000101474280000022.png"\; state="\{\{state\}\}">VTE</figure-callout>}{C}_{}{}_1+a_2\mathrm{<figure-callout\; id="2"\; label="VTE\; C"\; filenames="HSA0000101474280000031.png,HSA0000101474280000032.png"\; state="\{\{state\}\}">VTE</figure-callout>}{C}_{}{}_2$

$\mathrm{TEC}=\widehat{\mathrm{VTEC}}/\cos z\&prime;$

Wherein,

for revised zenith direction ionospheric electron density, VTEC1 is the zenith direction electron concentration that step 1 is calculated, VTEC ₂for step 2 is calculated zenith direction ionospheric electron density, a ₀, a ₁, a ₂for the regression coefficient of revised zenith direction ionospheric electron density linear equation in two unknowns, according to the conception of history measured value of zenith direction ionospheric electron density and its corresponding historical calculated value, utilize least square method to determine a ₀, a ₁with a ₂.

The technology of the present invention beneficial effect:

The present invention is based on two-frequency signal, comprehensive utilization code phase observed reading and carrier phase observation data, adopt linear regression method, calculate the zenith direction ionospheric electron density of having considered satellite and receiver delay distortion, and then the ionospheric electron density of definite signal propagation path.Owing to having adopted high precision double frequency data, code phase observed reading and carrier phase observation data are fully utilized, and adopt homing method, historical summary is applied in the accounting equation of ionospheric electron density by determining of regression coefficient, reach raising ionospheric electron density computational accuracy, and then the object of raising space flight measurement and control signal ionosphere delay correction precision, there is significant application value in the technical field such as space flight measurement and control, communication and navigation.

Accompanying drawing explanation

Fig. 1 is ionosphere single-layer model SLM schematic diagram.

Fig. 2 is ionospheric electron density computation process process flow diagram of the present invention.

Fig. 3 is the ionospheric electron density value schematic diagram in 19 days October in 2010 that adopts the inventive method to calculate in lunar exploration satellite space flight measurement and control.

Fig. 4 is the ionospheric electron density value schematic diagram in October in 2010 20 that adopts the inventive method to calculate in lunar exploration satellite space flight measurement and control.

Fig. 5 is the track residual error schematic diagram that the ionosphere delay correction that adopts the inventive method definite ionospheric electron density value to carry out is calculated.

Fig. 6 is the track residual error schematic diagram that the ionosphere delay correction that adopts classic method definite ionospheric electron density value to carry out is calculated.

Embodiment

Below in conjunction with accompanying drawing, be modified to example with the ionosphere delay of measurement and control signal in a lunar exploration satellite task, the present invention is described further.

At present in the technical field such as space flight measurement and control, communication and navigation, while relating to signal correction, need to calculate ionospheric electron density, total electron content TEC runs through along signal propagation path the total electron number comprising in a whole ionospheric cylinder, along signal propagation path s ' to electron density N _ecarry out the result of integration.

$\mathrm{TEC}=\underset{s^{\&prime;}}{\&Integral;}{N}_e\mathrm{ds}$

TEC is the function of direction, and elevation angle and the position angle of propagating with signal change; Wherein position angle impact is less, can ignore.And for space flight measurement and control signal, adopt the TEC of zenith direction while being 90 ° (be elevation angle) to study, and be designated as VTEC.VTEC adopts single-layer model SLM to calculate, in SLM supposition ionosphere, all electronics concentrate on the unlimited thin individual layer of a thickness, the height of individual layer is generally chosen near 350km (the maximum layer of electron concentration), and SLM simplifies complicated ionospheric structure greatly, as shown in Figure 1.Found out by Fig. 1:

VTEC＝TEC.cosz′

Wherein, z ' is the zenith distance that the intersection point P ' of signal path and individual layer locates sense, and cosz ' is inclination factor.The calculating that can be equal to VTEC of determining to TEC thus.

If the carrier signal of two frequencies of Spacecraft Launch, because the signal of two kinds of different frequencies is along same propagated, both have identical TEC, can utilize thus two-frequency signal correction ionospheric electron density calculated amount.Principle is as follows:

For two-frequency signal, v _g, v _p, △ t, △ t ' are respectively signal velocity and the time of code phase measuring, carrier phase measurement, and satellite to the actual distance ρ of receiver is so:

$\begin{array}{c}\mathrm{\&rho;}=\underset{\mathrm{\&Delta;t}}{\&Integral;}{v}_g\&CenterDot;\mathrm{dt}=\underset{\mathrm{\&Delta;t}}{\&Integral;}C\&CenterDot;(1-40.28\&CenterDot;N_e\&CenterDot;f^{-2})\&CenterDot;\mathrm{dt}\\ =C\&CenterDot;\mathrm{\&Delta;t}-40.28\&CenterDot;f^{-2}\&CenterDot;\underset{s^{\&prime;}}{\&Integral;}{N}_e\mathrm{ds}\\ =p-40.28\&CenterDot;f^{-2}\&CenterDot;\underset{s^{\&prime;}}{\&Integral;}{N}_e\mathrm{ds}=p-40.28\&CenterDot;f^{-2}\&CenterDot;\mathrm{TEC}\end{array}---\left(1\right)$

Wherein, C represents the light velocity, and f is frequency, and P is code phase observed reading, and λ is carrier wavelength, for phase observations value, the integer ambiguity that N is carrier wave.Above-mentioned two formula about ρ show, owing to there being ionosphere delay, so the distance of code phase measuring is longer than actual distance, and carrier phase range finding is from shorter than actual distance.

Make the ionosphere delay in code phase measuring correct as (△ _ion) _g, the ionosphere delay in carrier phase measurement corrects as (△ _ion) _p, TEC is with 10 ¹⁶electron number/rice ²for unit, signal frequency f, take GHz as unit, has:

For being modulated at L ₁and L ₂the measured code phase P of ranging code on carrier wave ₁and P ₂, its ionosphere delay corrects and is respectively:

(3)

For L ₁and L ₂carrier phase, its ionosphere delay corrects and is respectively:

(4)

Owing to having above-mentioned corresponding relation between ionosphere delay and TEC, VTEC, be suitable so set up ionosphere delay model with setting up VTEC model.Therefore the present invention calculates VTEC in conjunction with code phase measuring and the carrier phase measurement of two-frequency signal, and then by homing method structure accounting equation correction VTEC value, as shown in Figure 2, specifically comprises the steps:

Step 1, use dual-frequency code phase observations value are calculated zenith direction electron concentration VTE C ₁

Have according to formula (1), (2), (3):

$\left\{\begin{array}{c}\mathrm{\&rho;}=P_1-0.162292\mathrm{TEC}+{\mathrm{\&sigma;}}_1\\ \mathrm{\&rho;}=P_2-0.267286\mathrm{TEC}+{\mathrm{\&sigma;}}_2\end{array}\right.$

:

TEC＝9.52437(P ₂-P ₁)+σ (5)

After the zenith direction that formula (5) reduction is located to the intersection point P ' of signal path and individual layer, obtain VTEC ₁computing method as follows:

VTEC ₁＝9.52437(P ₂-P ₁)·cos z′+σ ₁

Wherein, z ' is the zenith distance of signal path and individual layer intersection point place sense, P ₁be code phase observed reading, the P of the first frequency ₂be the code phase observed reading of the second frequency, σ ₁=-9.52437cosz ' B, B represents ionosphere delay deviation poor of the code phase observed reading of two frequencies.

Step 2, use dual-frequency carrier observed reading are calculated zenith direction electron concentration VTEC ₂

Have according to formula (1), (2), (4):

:

Formula (6) reduction, to zenith direction, is obtained with the equation of dual-frequency carrier observed reading calculating zenith direction electron concentration as follows:

VTEC ₂＝9.52437[(λ ₁φ ₁-λ ₂φ ₂)+(λ ₁N ₁-λ ₂N ₂)]·cos z′+σ ₂

Wherein, λ ₁be carrier wavelength, the λ of the first frequency ₂be the carrier wavelength of the second frequency, φ ₁be the first frequency carrier phase observation data, φ ₂be the second frequency carrier phase observation data, N ₁be integer ambiguity, the N of the first frequency carrier wave ₂be the integer ambiguity of the second frequency carrier wave, σ ₂=9.52437cosz ' L _g, L _grepresent ionosphere delay deviation poor of the carrier phase observation data of two frequencies.

Step 3, determine ionospheric electron density TEC

$\widehat{\mathrm{VTEC}}=a_0+a_1\mathrm{<figure-callout\; id="1"\; label="VTE\; C"\; filenames="HSA0000101474280000022.png"\; state="\{\{state\}\}">VTE</figure-callout>}{C}_{}{}_1+a_2\mathrm{<figure-callout\; id="2"\; label="VTE\; C"\; filenames="HSA0000101474280000031.png,HSA0000101474280000032.png"\; state="\{\{state\}\}">VTE</figure-callout>}{C}_{}{}_2$

$\mathrm{TEC}=\widehat{\mathrm{VTEC}}/\cos z\&prime;$

Wherein, for revised zenith direction ionospheric electron density, VTEC ₁for the zenith direction electron concentration that step 1 is calculated, VTEC ₂for step 2 is calculated zenith direction ionospheric electron density, a ₀, a ₁, a ₂for the regression coefficient of revised zenith direction ionospheric electron density linear equation in two unknowns, according to the conception of history measured value of zenith direction ionospheric electron density and its corresponding historical calculated value, utilize least square method to determine a ₀, a ₁with a ₂.

Adopt in the lunar exploration satellite space flight measurement and control of the inventive method calculating, the ionospheric electron density value of 2010-10-19 to 2010-10-20, as Fig. 3, shown in Fig. 4.

The ionospheric electron density value that the inventive method is calculated is applied in lunar exploration satellite space flight measurement and control example, the track residual error of the ionosphere delay corrected Calculation that the definite ionospheric electron density value of employing the inventive method on October 21st, 2010 is carried out, as shown in Figure 5.The track residual error that adopts ionosphere delay correction that traditional ionospheric model carries out to calculate, as shown in Figure 6, from Fig. 5, Fig. 6, adopt the inventive method to improve the computational accuracy of zenith direction ionospheric electron density, and then improved the correction precision of ionosphere delay, make track calculate residual error and reduce 2%.

Claims (1)

1. ionospheric electron density is determined a method, it is characterized in that: comprise the steps:

Step 1, use dual-frequency code phase observations value are calculated zenith direction electron concentration VTEC ₁

VTEC ₁＝9.52437(P ₂-P ₁)·cosz′+σ ₁

Wherein, z ' is the zenith distance of signal path and individual layer intersection point place sense, P ₁be code phase observed reading, the P of the first frequency ₂be the code phase observed reading of the second frequency, σ ₁=-9.52437.cosz ' B, B represents ionosphere delay deviation poor of the code phase observed reading of two frequencies;

Step 2, use dual-frequency carrier observed reading are calculated zenith direction electron concentration VTEC ₂

VTEC ₂＝9.52437[(λ ₁φ ₁-λ ₂φ ₂)+(λ ₁N ₁-λ ₂N ₂)]·cosz′+σ ₂

Wherein, λ ₁the carrier wavelength, the λ 2 that are the first frequency are the carrier wavelength of the second frequency, φ ₁be the first frequency carrier phase observation data, φ ₂be the second frequency carrier phase observation data, N ₁be integer ambiguity, the N of the first frequency carrier wave ₂be the integer ambiguity of the second frequency carrier wave, σ ₂=9.52437cosz ' L _g, L _grepresent ionosphere delay deviation poor of the carrier phase observation data of two frequencies;

Step 3, determine ionospheric electron density TEC

$\widehat{\mathrm{VTEC}}=a_0+a_1\mathrm{VTE}{C}_1+a_2\mathrm{VTE}{C}_2$

$\mathrm{TEC}=\widehat{\mathrm{VTEC}}/\cos z\&prime;$

Wherein,

for revised zenith direction ionospheric electron density, VTEC1 is the zenith direction electron concentration that step 1 is calculated, VTEC ₂for step 2 is calculated zenith direction ionospheric electron density, a ₀, a ₁, a ₂for the regression coefficient of revised zenith direction ionospheric electron density linear equation in two unknowns, according to the conception of history measured value of zenith direction ionospheric electron density and its corresponding historical calculated value, utilize least square method to determine a ₀, a ₁with a ₂.

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