CN102213765B - Marine reflection radio-frequency signal generating system - Google Patents

Abstract

The invention discloses a marine reflection radio-frequency signal generating system which comprises a parameter computing and real-time updating module, an intermediate-frequency navigation signal generating module, a DAC (Digital-to-Analog Converter) module and an up-conversion module, wherein the parameter computing and real-time updating module is used for generating the accumulating parameters and power control codes corresponding to the observation data of direct star and marine reflection; the intermediate-frequency navigation signal generating module utilizes the input accumulating parameters and power control codes to generate the digital intermediate-frequency simulation signals of the direct star and marine reflection; and the DAC module and the up-conversion module convert the digital intermediate-frequency simulation signals into radio-frequency signals to be output. The marine reflection radio-frequency signal generating system disclosed by the invention can simulate the marine reflection radio-frequency signals of a navigation satellite and realize the physical radio-frequency signal simulation of the relevant waveforms on the pseudo code offset, power attenuation and Doppler frequency offset of various sea surface environments.

Description

A kind of marine reflection radio-frequency signal generating system

Technical field

The invention belongs to the Satellite Navigation Technique field, relate to a kind of marine reflection radio-frequency signal generating system.

Background technology

GNSS-R (Global Navigation Satellite System-Reflection) technology can be regarded as the expansion that GNSS (Global Navigation Satellite System) uses as a new research field.It utilizes the satellite sea return, in conjunction with the radar detection principle, for the ocean remote sensing technology has been brought new means.The GNSS-R technology successfully has been applied to the inverting of Ocean Wind-field, sea level height, sea surface roughness, significant wave height, seawater salinity, ice layer thickness and soil moisture etc. at present.

To the research of Yu Haiyang reflected signal emulation technology, can be divided into pure software emulation and radiofrequency signal emulation, present research both domestic and external mainly concentrates on the pure software simulation stage.For pure software emulation, set up mathematical model according to a large amount of observation datas of outfield experiments accumulation, carry out the emulation of ocean reflected signal by the mode of software programming, mainly for the research and development of non real-time software receiver.And radiofrequency signal emulation, according to the mathematic simulated mode of ocean reflected signal, Reality simulation marine environment reflected signal, real-time generation physical oceanography reflected radio signal can be for the research and development of all kinds ocean reflection receivable machine.

At present really can be with Navsat ocean reflected signal as physical radio output, domestic research still belongs to the starting stage, has no open source literature abroad and delivers.And present emulation to navigation signal all is the two-dimensional simulation for pseudo-code skew and power attenuation.

Summary of the invention

The purpose that technology of the present invention is dealt with problems is: for the deficiencies in the prior art, provide a kind of marine reflection radio-frequency signal generating system.Adopt native system can simulate Navsat ocean reflected radio signal, realized the physical radio signal imitation of the three-dimensional waveform correlation of pseudo-code skew, power attenuation and Doppler frequency deviation to various seas environment.

Technical solution of the present invention is: a kind of marine reflection radio-frequency signal generating system, can respectively star and the ocean reflection observation data of going directly be processed rear simulation and simulate through star and ocean reflected radio signal, comprise calculation of parameter and real-time update module, intermediate frequency navigation signal generation module, DAC module and up-converter module.

Wherein, calculation of parameter and real-time update module: receive through star and the ocean reflection observation data of input, and generate respectively corresponding to exporting to intermediate frequency navigation signal generation module after the cumulative parameter of through star and ocean reflection observation data and the power control code.And comprise system made module, system initialization module and system maintaining module;

System made module: be responsible for the start-up time that whole signal generating system is set up beginning emulation, and will export to system maintaining module start-up time;

System initialization module: responsible external unit to calculation of parameter and real-time update module carries out initialization and intermediate frequency navigation signal generation module is resetted, and described external unit comprises pci bus and SDRAM;

System maintaining module: comprise emulation channel management module and cumulative parameter/power computation module, wherein, emulation channel management module is determined the unlatching/off state of through star and ocean reflection channel according to marine reflection radio-frequency signal generating system channel simulation quantity, through star emulation at most can 12 through star passages of emulation signal, the ocean reflected signal that the ocean reflection simulating at most can 32 passages of emulation; Cumulative parameter/power computation module receives through star and ocean reflection observation data and the start-up time of input, calculates cumulative parameter and the power of pseudo-code and carrier wave, the cumulative parameter, power control code and the output that produce through star and ocean reflection observation data; Wherein said through star and ocean reflection observation data comprise temporal information, satellite numbering, pseudorange, speed, acceleration, acceleration, power and carrier phase.

Intermediate frequency navigation signal generation module: output to the DAC module behind the digital intermediate frequency simulate signal of the cumulative parameter of utilization input, the through star of power control code generation and ocean reflection.

And described intermediate frequency navigation signal generation module comprises that the signal for generating digital intermediate frequency simulate signal generates passage; Described signal generates through star and the cumulative parameter of ocean reflection and the power control code that passage receives input, and described cumulative parameter comprises pseudo-code code ring parameter and carrier wave ring parameter; And obtain the phase place of carrier wave meter and code table according to cumulative calculation of parameter, tabling look-up in pseudo-code code table and carrier wave meter according to the phase place that calculates obtains carrier wave and code; Carrier wave and the pseudo-code that utilization obtains modulated, filtering, close after the road, multiplies each other with the power control code and carries out the power adjustment and obtain the digital intermediate frequency simulate signal.

The present invention compared with prior art has following advantage:

(1) the present invention has set up a kind of marine reflection radio-frequency signal generating system.This system is by obtaining through star/ocean reflected radio signal to the through star of outside input/ocean reflection observation data, and this method can realize the physical simulation of ocean reflected signal.The ocean reflected radio signal that simulates can satisfy the research and development requirement of ocean reflection receivable machine, and supports comprehensive index test of ocean reflection receivable machine.

(2) the present invention can simulate and calculate these three parameters of pseudo-code skew, Doppler frequency deviation and power attenuation by the cumulative parameter/power computation module in calculation of parameter and the real-time update module, and the result is added in the cumulative parameter and power control code of pseudo-code and carrier wave; These three parameters of pseudo-code skew, Doppler frequency deviation and power attenuation are independent calculating and stack, can control respectively three parameters like this, to realize flexible configuration.Thereby adjustment and emulation to the three-dimensional waveform correlation of sea environment have been realized.

(3) the present invention is reflected the at most ocean reflected signal of 32 passages of emulation to the at most signal of 12 through star passages of emulation of star that goes directly to the ocean.Can realize the independent of each passage controlled by the channel management module in calculation of parameter and the real-time update module, 32 ocean reflection pathss of single satellite can be set, many a plurality of oceans reflection pathss that star is corresponding also can be set, not only can carry out emulation to the two-dimentional radiofrequency signal that the ocean reflected signal carries out pseudo-code and power like this, can also carry out to the ocean reflected signal that comprises Doppler frequency deviation three-dimensional radiofrequency signal emulation.

Description of drawings

Fig. 1 is sea signal reflex synoptic diagram;

Fig. 2 is system construction drawing of the present invention;

Fig. 3 is calculation of parameter and real-time update module structural drawing;

Fig. 4 is intermediate frequency navigation signal generation module structural drawing;

Fig. 5 is intermediate-freuqncy signal generation module processing flow chart;

Fig. 6 is code ring, carrier wave ring three rank totalizer structural drawing.

Embodiment

Below in conjunction with accompanying drawing the specific embodiment of the invention is done further introduction.

Topmost difference is their related function waveform difference between through star signal and the ocean reflected signal.Through star signal is without sea surface reflection, and waveform is not distortion almost, and waveform correlation is a triangle.And ocean reflected signal waveform depends on the factors such as satellite geometry position, sea surface roughness, Radio wave incident angle degree, and waveform changes thereupon.The ocean reflected signal comes from the through star signal that the large tracts of land sea is reflected, and this reflecting surface is referred to as the echo area.When the reflected signal of diverse location arrives acceptance point in the echo area, have different time-delays and Doppler frequency deviation, and different according to sea surface roughness and Ocean Wind-field, the power of reflected signal also can be had any different, and the emulation of ocean reflected signal is exactly the signal simulation that will finish under these three factor affecting of pseudo-code, Doppler frequency deviation and power.

Fig. 1 is sea signal reflex synoptic diagram.The right of Fig. 1 represents that the pseudo-random code of Navsat incides the sea, is to be determined by the mirror reflection spot O between them because through star signal arrives the bee-line of receiver, and at first to be first chip offset signal, become the forward position of reflection configuration.Second chip offset echo area signal, the 3rd chip offset echo area signal subsequently ... the reflection configuration that is in the signal arrival receiver of same chip offset echo area is consistent; Doppler's line shown in Fig. 1 is take the mirror reflection spot as axisymmetric, and its Doppler frequency deviation of signal that is on the same Doppler line is consistent.Chip offset echo area and Doppler's line have been divided into a lot of zonules with this sheet echo area like this, and the zone division is meticulousr, and the precision of emulation is higher; According to the height of Navsat, the position of receiver and the impact of Ocean Wind-field and roughness, the power of each reflection spot is also different in addition.So just can draw the reflected signal waveform correlation shown in Fig. 1 lower left corner.The chip offset echo area is divided with half-chip among the present invention, and Doppler's line is divided with 200Hz.

Satellite navigation signals generally adopts the QPSK modulation, comprises carrier wave, pseudo-code and three kinds of information component of navigation message, and the expression formula that through star signal generates is as follows:

(1)

S wherein _ZThe through star signal of expression, A represents amplitude, and C, P represent respectively ranging code and precision code (being usually said pseudo-code), and D represents navigation message, f _mThe expression carrier frequency,

The expression first phase, τ (t) expression satellite-signal is to the signal transmission delay of receiver, and subscript m represents to defend asterisk, and subscript c, p represent respectively the respective amount of ranging code and precision code.

According to top analysis, the ocean reflected signal is to carry out Measurement and analysis by time delay and waveform correlation characteristic to pseudo-code, therefore the processing of reflecting part, ocean does not need to use navigation message information, and namely pseudo-code can directly be modulated to and generate intermediate-freuqncy signal on the carrier wave.Consider in addition power recited above, pseudo-code skew and three factors of Doppler frequency deviation, the expression formula that the ocean reflected signal generates is as follows:

(2)

S wherein _HExpression ocean reflected signal, δ _PowThe power attenuation amount of expression ocean reflected signal, δ _cThe pseudo-code side-play amount of expression ocean reflected signal, namely simulated point is in which chip offset echo area, δ _DoppThe Doppler shift amount of expression ocean reflected signal, namely which bar Doppler line is simulated point be on.

Satellite navigation ocean reflected signal generation system structure as shown in Figure 2, because ocean reflection receivable machine needs simultaneously through star signal and ocean reflected signal to be carried out code acquisition, and the star signal that will go directly carries out relevant with pseudo-code respectively with the ocean reflected signal, just can obtain ocean reflected signal waveform correlation as shown in Figure 1, so reflected signal generation method in ocean needs the through star signal of simultaneously emulation and ocean reflected signal.

The present invention has set up a kind of marine reflection radio-frequency signal generating system, this system comprises calculation of parameter and real-time update module, intermediate frequency navigation signal generation module, DAC module and up-converter module, can realize respectively the emulation to through star signal and ocean reflected signal.

Process through the calculation of parameter and the real-time update module that are realized by DSP by the through star observation data that mathematical simulation generates, and the intermediate frequency navigation signal generation module that the cumulative parameter of the through star of real-time update, power control code and navigation message are sent to by the FPGA realization generates intermediate-freuqncy signal, generate simulating signal by the DAC module, simulation simulates 12 through star radiofrequency signals after the up-conversion; Process through calculation of parameter and real-time update module equally by the ocean reflection observation data that mathematical simulation generates, and the cumulative parameter of the ocean of real-time update reflection, power control code sent to intermediate frequency navigation signal generation module and generate intermediate-freuqncy signal, generate simulating signal by DAC, simulation simulates the ocean reflected radio signal of 32 passages after the up-conversion.

Calculation of parameter and real-time update module

The calculation of parameter that through star and ocean reflection observation data are processed in real time that is made up by DSP and real-time update module structure mainly comprise system made, system initialization and system maintenance three functions module as shown in Figure 3.Wherein

The system made module mainly is responsible for whole signal generating system and sets up start-up time and export to system maintaining module.Described system refers to exact date and the time that system simulation simulation data simulate signal has start-up time.

System initialization module is responsible for before system emulation system being carried out initialization, provides reset signal by EMIF (external memory interface) for intermediate frequency navigation signal generation module.Simultaneously, system initialization module is responsible for also that the external unit to system carries out initialization before system emulation, comprises the initialization to PCI (peripheral component interconnect bus) bus and SDRAM, and intermediate frequency navigation signal generation module is resetted.Described pci bus is the data interaction of being responsible for carrying out between DSP and the host computer, lower the writing and the uploading etc. of channel status that comprises observation data, start-up time; Described SDRAM is that DSP carries out interim buffer memory to big data quantities such as texts when computing.

System maintaining module is the main functional modules of calculation of parameter and real-time update module, and the passage configuration of through star and ocean reflected signal and the flexible configuration of pseudo-code skew, power attenuation and Doppler frequency deviation all realize by this module.

System maintaining module reads through star observation data and ocean reflection observation data by pci bus, carry out the cumulative calculation of parameter of pseudo-code and text and the calculating of power by the cumulative parameter/power computation module of through star and the cumulative parameter/power computation module of ocean reflection respectively, and with result of calculation by real-time lower the writing to intermediate frequency navigation signal generation module of EMIF, also can descend in addition write through star navigation message in real time.Simultaneously, the cumulative parameter/power computation module of through star and the cumulative parameter/power computation module of ocean reflection also the pci bus of passing through that the status information of system is real-time be uploaded to host computer.

The observation data of ocean reflection comprises the theoretical pseudorange parameter to 32 ocean reflection spots, i.e. pseudorange initial value R ₀, pseudorange speed v, pseudorange acceleration a, pseudorange acceleration b.To Yu Haiyang reflection signal power damping capacity δ _PowSimulation in the reflective power computing module of ocean, finish, the power attenuation null value of the isolated ocean of observation data reflected signal is added to respectively on the corresponding through star performance number of each passage, finally draws to write under the power code of each passage and carry out subsequent treatment among the FPGA; To Yu Haiyang reflected signal pseudo-code offset delta _cWith Doppler frequency deviation amount δ _DoppSimulation in the cumulative parameter calculating module of ocean reflection, finish, with pseudorange (can directly from the reflection observed quantity of ocean, the obtain) pseudo-code that is added to respectively of a certain reflection spot reflected signal and the pseudorange initial value R of carrier wave ₀On, the Doppler frequency deviation amount of this reflection spot is added to respectively on the pseudorange speed v component of pseudo-code and carrier wave, carry out subsequent treatment among the FPGA through writing under the three rank totalizer coefficients that calculate pseudo-code and carrier wave.Reflect cumulative parameter/power computation module to the calculating stack of power attenuation, pseudo-code skew and Doppler frequency deviation by the ocean, thereby realized the three-dimensional simulation emulation to the sea surface reflection zone.

The passage configuration feature of through star and ocean reflected signal is realized by emulation channel management module.For 12 passages of through star, can set up no more than 12 arbitrarily satellite and keep, and can cancel arbitrarily wherein certain satellite and set up and keep an other satellite, namely change star; 32 passages to the Yu Haiyang reflection, both can carry out the two-dimensional simulation of identical Doppler frequency deviation, also can carry out the three-dimensional artificial of different Doppler frequency deviations, 32 ocean reflection pathss of single satellite both can be set, many a plurality of oceans reflection pathss that star is corresponding also can be set, as long as the ocean reflection paths quantity summation of institute's emulation is 32 the tunnel.Also can arbitrarily change simultaneously star processes.Like this, each passage of through star and ocean reflected signal can both be realized independently controlling.

The calculating of cumulative parameter comprises calculating two parts of pseudo-code code ring and carrier wave ring three rank totalizer parameters.Calculating pseudo-code code ring parameter is undertaken by following formula:

${\mathrm{<figure-callout\; id="0"\; label="k"\; filenames="HSA00000450073600011.png"\; state="\{\{state\}\}">k</figure-callout>}}_0={\mathrm{<figure-callout\; id="0"\; label="K"\; filenames="HSA00000450073600011.png"\; state="\{\{state\}\}">K</figure-callout>}}_0\&times;2^{{\mathrm{<figure-callout\; id="0"\; label="M"\; filenames="HSA00000450073600011.png"\; state="\{\{state\}\}">M</figure-callout>}}_0}$

${\mathrm{<figure-callout\; id="1"\; label="k"\; filenames="HSA00000450073600022.png"\; state="\{\{state\}\}">k</figure-callout>}}_1=2^{{\mathrm{<figure-callout\; id="1"\; label="C"\; filenames="HSA00000450073600022.png"\; state="\{\{state\}\}">C</figure-callout>}}_1}\&times;({\mathrm{<figure-callout\; id="1"\; label="K"\; filenames="HSA00000450073600022.png"\; state="\{\{state\}\}">K</figure-callout>}}_1+\frac{K_2}{2}+\frac{K_3}{6})\&times;2^{{\mathrm{<figure-callout\; id="0"\; label="M"\; filenames="HSA00000450073600011.png"\; state="\{\{state\}\}">M</figure-callout>}}_0}$

$k_2=2^{{\mathrm{<figure-callout\; id="1"\; label="C"\; filenames="HSA00000450073600022.png"\; state="\{\{state\}\}">C</figure-callout>}}_1+C_2}\&times;(K_2+K_3)\&times;2^{M_1}---\left(3\right)$

$k_3=2^{{\mathrm{<figure-callout\; id="1"\; label="C"\; filenames="HSA00000450073600022.png"\; state="\{\{state\}\}">C</figure-callout>}}_1+C_2}\&times;K_3\&times;2^{M_2}$

Wherein, k ₀, k ₁, k ₂And k ₃Be pseudo-code code ring parameter, K ₀, K ₁, K ₂And K ₃Be intermediate variable

${\mathrm{<figure-callout\; id="0"\; label="K"\; filenames="HSA00000450073600011.png"\; state="\{\{state\}\}">K</figure-callout>}}_0=\frac{R_0}{c},$ ${\mathrm{<figure-callout\; id="1"\; label="K"\; filenames="HSA00000450073600022.png"\; state="\{\{state\}\}">K</figure-callout>}}_1=\frac{v}{{\mathrm{cf}}_s},$ $K_2=\frac{a}{{\mathrm{cf}}_s^2},$ $K_3=\frac{b}{{\mathrm{cf}}_s^3}---\left(4\right)$

R ₀Be the pseudorange initial value, v is speed, and a is acceleration, and b is acceleration, and c is the light velocity, f _sBe sample frequency.

C ₁And C ₂For blocking figure place, and have

${\mathrm{<figure-callout\; id="1"\; label="C"\; filenames="HSA00000450073600022.png"\; state="\{\{state\}\}">C</figure-callout>}}_1={\log }_2\left(\frac{\mathrm{\&Delta;v}\&CenterDot;f_s}{\mathrm{\&Delta;a}}\right),$ $C_2={\log }_2\left(\frac{\mathrm{\&Delta;a}\&CenterDot;f_s}{\mathrm{\&Delta;b}}\right)---\left(5\right)$

Δ v is velocity resolution, and Δ a is acceleration resolution, and Δ b is acceleration resolution.

M ₀, M ₁And M ₂Be the bit wide of pseudo-code three rank totalizers, and have

${\mathrm{<figure-callout\; id="0"\; label="M"\; filenames="HSA00000450073600011.png"\; state="\{\{state\}\}">M</figure-callout>}}_0={\log }_2\left(\frac{c\&CenterDot;f_s}{\mathrm{\&Delta;v}\&CenterDot;f_m}\right),$ ${\mathrm{<figure-callout\; id="1"\; label="M"\; filenames="HSA00000450073600022.png"\; state="\{\{state\}\}">M</figure-callout>}}_1={\log }_2\left(\frac{v_{\max }\&CenterDot;f_s}{\mathrm{\&Delta;a}}\right),$ $M_2={\log }_2\left(\frac{a_{\max }\&CenterDot;f_s}{\mathrm{\&Delta;b}}\right)---\left(6\right)$

v _MaxThe speed maximal value, a _MaxThe acceleration maximal value, f _mPseudo-code code clock frequency, Δ v, Δ a, Δ b, v _Max, a _MaxAnd f _mIt is the preset value of described marine reflection radio-frequency signal generating system.

Calculating carrier wave ring parameter is undertaken by following formula:

${\mathrm{<figure-callout\; id="0"\; label="k"\; filenames="HSA00000450073600011.png"\; state="\{\{state\}\}">k</figure-callout>}}_0={\mathrm{<figure-callout\; id="0"\; label="K"\; filenames="HSA00000450073600011.png"\; state="\{\{state\}\}">K</figure-callout>}}_0\&times;2^{{\mathrm{<figure-callout\; id="0"\; label="M"\; filenames="HSA00000450073600011.png"\; state="\{\{state\}\}">M</figure-callout>}}_0}$

${\mathrm{<figure-callout\; id="1"\; label="k"\; filenames="HSA00000450073600022.png"\; state="\{\{state\}\}">k</figure-callout>}}_1=2^{{\mathrm{<figure-callout\; id="1"\; label="C"\; filenames="HSA00000450073600022.png"\; state="\{\{state\}\}">C</figure-callout>}}_1}\&times;({\mathrm{<figure-callout\; id="1"\; label="K"\; filenames="HSA00000450073600022.png"\; state="\{\{state\}\}">K</figure-callout>}}_1+\frac{K_2}{2}+\frac{K_3}{6})\&times;2^{{\mathrm{<figure-callout\; id="0"\; label="M"\; filenames="HSA00000450073600011.png"\; state="\{\{state\}\}">M</figure-callout>}}_0}$

$k_2=2^{{\mathrm{<figure-callout\; id="1"\; label="C"\; filenames="HSA00000450073600022.png"\; state="\{\{state\}\}">C</figure-callout>}}_1+C_2}\&times;(K_2+K_3)\&times;2^{M_1}---\left(7\right)$

$k_3=2^{{\mathrm{<figure-callout\; id="1"\; label="C"\; filenames="HSA00000450073600022.png"\; state="\{\{state\}\}">C</figure-callout>}}_1+C_2}\&times;K_3\&times;2^{M_2}$

Wherein, k ₀, k ₁, k ₂And k ₃Be carrier wave ring parameter, K ₀, K ₁, K ₂And K ₃Be intermediate variable, and

${\mathrm{<figure-callout\; id="0"\; label="K"\; filenames="HSA00000450073600011.png"\; state="\{\{state\}\}">K</figure-callout>}}_0=\frac{R_0}{c},$ ${\mathrm{<figure-callout\; id="1"\; label="K"\; filenames="HSA00000450073600022.png"\; state="\{\{state\}\}">K</figure-callout>}}_1=\frac{v}{{\mathrm{cf}}_s},$ $K_2=\frac{a}{{\mathrm{cf}}_s^2},$ $K_3=\frac{b}{{\mathrm{cf}}_s^3}---\left(8\right)$

R ₀Be the pseudorange initial value, v is speed, and a is acceleration, and b is acceleration, and c is the light velocity, f _sBe sample frequency.

C ₁And C ₂For blocking figure place, and have

${\mathrm{<figure-callout\; id="1"\; label="C"\; filenames="HSA00000450073600022.png"\; state="\{\{state\}\}">C</figure-callout>}}_1={\log }_2\left(\frac{\mathrm{\&Delta;v}\&CenterDot;f_s}{\mathrm{\&Delta;a}}\right),$ $C_2={\log }_2\left(\frac{\mathrm{\&Delta;a}\&CenterDot;f_s}{\mathrm{\&Delta;b}}\right)---\left(9\right)$

Δ v is velocity resolution, and Δ a is acceleration resolution, and Δ b is acceleration resolution.

M ₀, M ₁And M ₂Be the bit wide of carrier wave ring three rank totalizers, and have

${\mathrm{<figure-callout\; id="0"\; label="M"\; filenames="HSA00000450073600011.png"\; state="\{\{state\}\}">M</figure-callout>}}_0={\log }_2\left(\frac{c\&CenterDot;f_s}{\mathrm{\&Delta;v}\&CenterDot;f_m}\right),$ ${\mathrm{<figure-callout\; id="1"\; label="M"\; filenames="HSA00000450073600022.png"\; state="\{\{state\}\}">M</figure-callout>}}_1={\log }_2\left(\frac{v_{\max }\&CenterDot;f_s}{\mathrm{\&Delta;a}}\right),$ $M_2={\log }_2\left(\frac{a_{\max }\&CenterDot;f_s}{\mathrm{\&Delta;b}}\right)---\left(10\right)$

v _MaxThe speed maximal value, a _MaxThe acceleration maximal value, f _mCarrier frequency, Δ v, Δ a, Δ b, v _Max, a _MaxAnd f _mIt is the preset value of described marine reflection radio-frequency signal generating system.

The power calculation of through star and ocean reflection channel is calculated by following formula:

$K=K_A\&CenterDot;\sqrt{\frac{P_s+K_{\mathrm{sv}\_r}-3}{P_{s0}}}\&CenterDot;\frac{1}{N}---\left(11\right)$

Wherein K is the power control code, K _AControl code when being the emulation single channel during power maximal value, P _sThe performance number in the observation data, K _{Sv_r}Be emulation passage number modifying factor, N is the emulation total number of channels, P _S0It is the minimum of power in the observation data.

Simultaneously, the cumulative parameter/power computation module of through star and the cumulative parameter/power computation module of ocean reflection also the pci bus of passing through that the status information of system is real-time be uploaded to host computer.Described status information comprises the information such as power control code, pseudo-code code ring and carrier wave ring parameter of being calculated by the cumulative parameter/power computation module of through star and the cumulative parameter/power computation module of ocean reflection, and these information will real-time showing in the host computer interface.

In addition, also comprise time maintenance module among Fig. 3, this module be used for to be responsible for receives the look-at-me that intermediate frequency navigation signal generation module provides, and time maintenance module is set up the time system of calculation of parameter and real-time update module according to look-at-me, is used for carrying out data processing and computing.

Intermediate frequency navigation signal generation module

The cumulative parameter of through star after process calculation of parameter and the real-time update module computing and power control code, the cumulative parameter of ocean reflection and power control code and navigation message are sent in the intermediate frequency navigation signal generation module by EMIF, and its structure as shown in Figure 4.Intermediate frequency navigation signal generation module reads in the pseudo-code of maximum 12 tunnel through star passages and maximum 32 tunnel ocean reflection channels and the navigation message of carrier wave cumulative parameter, power control code and through star by data read-write module, the a plurality of through star signal of sending into structural similarity generates passage and ocean reflected signal generation passage, and signal generates passage and carry out the data processing under unified look-at-me control; Generate through star intermediate-freuqncy signal and ocean reflection intermediate-freuqncy signal and output.

Generate in the passage to signal processing flow as shown in Figure 5 at signal.Intermediate frequency navigation signal generation module arranges pseudo-code code ring and carrier wave ring three rank totalizer parameters according to the data by calculation of parameter and real-time update module output that receive, wherein, pseudo-code three rank totalizers are according to the timeticks of system, export in real time the pseudo-code phase retardation, and and the output valve addition of pseudo-code phase totalizer generate pseudo-code phase, drive pseudo-code generator and generate pseudo-random code stream; Carrier wave three rank totalizers are according to the timeticks of system, real-time outgoing carrier phase-delay quantity, and and the output valve addition of carrier phase totalizer generate carrier phase, according to carrier phase output digital carrier; Pseudo-code and navigation message are modulated on the digital carrier, generate intermediate-freuqncy signal.Generate the difference part as shown in phantom in Figure 5 of through star intermediate-freuqncy signal and ocean reflection intermediate-freuqncy signal.Ocean reflection intermediate-freuqncy signal does not need to modulate navigation message.

τ (t) in formula (1) and (2) can specifically be expressed as:

$\mathrm{\&tau;}\left(t\right)=\frac{R\left(t\right)}{C}=\frac{{\mathrm{<figure-callout\; id="0"\; label="R"\; filenames="HSA00000450073600011.png"\; state="\{\{state\}\}">R</figure-callout>}}_0+\mathrm{vt}+\frac{1}{2}{\mathrm{at}}^2+\frac{1}{6}{\mathrm{bt}}^3}{C}---\left(12\right)$

Here, R (t) is constantly pseudorange of t, R ₀, v, a, b be the three rank Taylor expansion coefficients of R (t), R ₀Be the pseudorange initial value, v is speed, and a is acceleration, and b is acceleration, and C is the light velocity.R ₀, v, a, b obtain from through star and ocean reflection observation data in real time.

High Precision Simulation for satellite navigation signals, key is exactly the High Precision Simulation of realizing τ (t), for radiofrequency signal emulation, if by formula directly calculate (12), generate simulating signal by the high-speed DAC conversion, be difficult to realize in real time and high-accuracy navigation signal emulation.The present invention adopts the synthetic method of Direct Digital to realize the emulation of high-accuracy navigation signal, adopted three rank carrier wave ring totalizers and three rank pseudo-code code ring totalizers realizations to the emulation of τ (t) in the formula (12), convert the multiplication in the following formula and Floating-point Computation the additive operation of fixed point to, be convenient to real-time implementation in FPGA.

Fig. 6 has provided three rank totalizer D of carrier wave ring and pseudo-code ₀, D ₁And D ₂Schematic diagram, its signal is output as the phase place of carrier wave or pseudo-code code clock, expression formula is seen following formula:

$\mathrm{\&tau;}\left(n\right)={\mathrm{<figure-callout\; id="0"\; label="k"\; filenames="HSA00000450073600011.png"\; state="\{\{state\}\}">k</figure-callout>}}_0\&CenterDot;2^{{\mathrm{<figure-callout\; id="0"\; label="M"\; filenames="HSA00000450073600011.png"\; state="\{\{state\}\}">M</figure-callout>}}_0}+(\frac{{\mathrm{<figure-callout\; id="1"\; label="k"\; filenames="HSA00000450073600022.png"\; state="\{\{state\}\}">k</figure-callout>}}_1}{2^{{\mathrm{<figure-callout\; id="1"\; label="C"\; filenames="HSA00000450073600022.png"\; state="\{\{state\}\}">C</figure-callout>}}_1}}\&CenterDot;2^{M_0}-\frac{k_2}{2\&times;2^{C_2+{\mathrm{<figure-callout\; id="1"\; label="C"\; filenames="HSA00000450073600022.png"\; state="\{\{state\}\}">C</figure-callout>}}_1}}\&CenterDot;2^{{\mathrm{<figure-callout\; id="1"\; label="M"\; filenames="HSA00000450073600022.png"\; state="\{\{state\}\}">M</figure-callout>}}_1}+\frac{k_3}{3\&times;2^{C_2+{\mathrm{<figure-callout\; id="1"\; label="C"\; filenames="HSA00000450073600022.png"\; state="\{\{state\}\}">C</figure-callout>}}_1}}\&CenterDot;2^{M_2})n$ (13)

$+\left(\frac{k_2\&CenterDot;2^{M_1}-k_3\&CenterDot;2^{M_2}}{2\&times;2^{{\mathrm{<figure-callout\; id="1"\; label="C"\; filenames="HSA00000450073600022.png"\; state="\{\{state\}\}">C</figure-callout>}}_1+C_2}}\right)n^2+\left(\frac{k_3\&CenterDot;2^{M_2}}{2\&times;3\&times;2^{{\mathrm{<figure-callout\; id="1"\; label="C"\; filenames="HSA00000450073600022.png"\; state="\{\{state\}\}">C</figure-callout>}}_1+C_2}}\right)n^3$

K wherein ₀, k ₁, k ₂, k ₃, C ₁, C ₂, M ₀, M ₁And M ₂Implication referring to formula (3)～(10),

Be f to formula (13) with frequency _sSample order

Can get

$\mathrm{\&tau;}\left(n\right)={\mathrm{<figure-callout\; id="0"\; label="K"\; filenames="HSA00000450073600011.png"\; state="\{\{state\}\}">K</figure-callout>}}_0+K_{1}n+\frac{K_2}{2}{n}^2+\frac{K_3}{6}{n}^3(n\&GreaterEqual;0)---\left(14\right)$

Wherein

Analogy formula (13) and (14), namely

Can obtain k ₀, k ₁, k ₂, k ₃Computing formula:

${\mathrm{<figure-callout\; id="0"\; label="k"\; filenames="HSA00000450073600011.png"\; state="\{\{state\}\}">k</figure-callout>}}_0={\mathrm{<figure-callout\; id="0"\; label="K"\; filenames="HSA00000450073600011.png"\; state="\{\{state\}\}">K</figure-callout>}}_0\&times;2^{{\mathrm{<figure-callout\; id="0"\; label="M"\; filenames="HSA00000450073600011.png"\; state="\{\{state\}\}">M</figure-callout>}}_0}$

${\mathrm{<figure-callout\; id="1"\; label="k"\; filenames="HSA00000450073600022.png"\; state="\{\{state\}\}">k</figure-callout>}}_1=2^{{\mathrm{<figure-callout\; id="1"\; label="C"\; filenames="HSA00000450073600022.png"\; state="\{\{state\}\}">C</figure-callout>}}_1}\&times;({\mathrm{<figure-callout\; id="1"\; label="K"\; filenames="HSA00000450073600022.png"\; state="\{\{state\}\}">K</figure-callout>}}_1+\frac{K_2}{2}+\frac{K_3}{6})\&times;2^{{\mathrm{<figure-callout\; id="0"\; label="M"\; filenames="HSA00000450073600011.png"\; state="\{\{state\}\}">M</figure-callout>}}_0}$

$k_2=2^{{\mathrm{<figure-callout\; id="1"\; label="C"\; filenames="HSA00000450073600022.png"\; state="\{\{state\}\}">C</figure-callout>}}_1+C_2}\&times;(K_2+K_3)\&times;2^{M_1}---\left(15\right)$

$k_3=2^{{\mathrm{<figure-callout\; id="1"\; label="C"\; filenames="HSA00000450073600022.png"\; state="\{\{state\}\}">C</figure-callout>}}_1+C_2}\&times;K_3\&times;2^{M_2}$

Utilize formula (15), according to the R that from through star and ocean reflection observation data, obtains ₀, v, a and b, can realize the high dynamic high precision signal simulation.

Obtain the phase place of carrier wave meter and pseudo-code code table according to go directly star and ocean reflection pseudo-code code ring parameter and carrier wave ring calculation of parameter, table look-up in pseudo-code code table and carrier wave meter according to this phase place and to obtain carrier wave and pseudo-code, the carrier wave and the pseudo-code that obtain are modulated, filtering, closed after the road, multiply each other with the through star that calculates according to formula (11) and ocean reflective power control code and carry out that the power adjustment obtains through star and ocean reflection digital intermediate frequency simulate signal is exported to the DAC module; Generate simulating signal through DAC, can generate through star radiofrequency signal and ocean reflected radio signal is launched by up-conversion.

Clock module among Fig. 5 is responsible for intermediate frequency navigation signal generation module global clock is provided, and provides look-at-me for calculation of parameter and real-time update module simultaneously.

The unspecified part of the present invention belongs to general knowledge as well known to those skilled in the art.

Claims (1)

1. marine reflection radio-frequency signal generating system, can respectively star and the ocean reflection observation data of going directly be processed rear simulation and simulate through star and ocean reflected radio signal, through star observation data and ocean reflection observation data generate by mathematical simulation, comprise, calculation of parameter and real-time update module, intermediate frequency navigation signal generation module, DAC module and up-converter module, it is characterized in that: described calculation of parameter and real-time update module and intermediate frequency navigation signal generation module

Calculation of parameter and real-time update module: receive through star and the ocean reflection observation data of input, and generate respectively corresponding to exporting to intermediate frequency navigation signal generation module after the cumulative parameter of through star and ocean reflection observation data and the power control code;

Intermediate frequency navigation signal generation module: output to the DAC module behind the digital intermediate frequency simulate signal of the cumulative parameter of utilization input, the through star of power control code generation and ocean reflection;

Described calculation of parameter and real-time update module comprise system made module, system initialization module and system maintaining module; Wherein,

System made module: be responsible for the start-up time that whole signal generating system is set up beginning emulation, and will export to system maintaining module start-up time;

System initialization module: responsible external unit to calculation of parameter and real-time update module carries out initialization and intermediate frequency navigation signal generation module is resetted, and described external unit comprises pci bus and SDRAM;

System maintaining module: comprise emulation channel management module and cumulative parameter/power computation module, wherein, emulation channel management module is determined the unlatching/off state of through star and ocean reflection channel according to marine reflection radio-frequency signal generating system channel simulation quantity, through star emulation at most can 12 through star passages of emulation signal, the ocean reflected signal that the ocean reflection simulating at most can 32 passages of emulation; Cumulative parameter/power computation module receives through star and ocean reflection observation data and the start-up time of input, calculates cumulative parameter and the power of pseudo-code and carrier wave, the cumulative parameter, power control code and the output that produce through star and ocean reflection observation data; Wherein said through star and ocean reflection observation data comprise temporal information, satellite numbering, pseudorange, speed, acceleration, acceleration, power and carrier phase;

Described intermediate frequency navigation signal generation module comprises that the signal for generating digital intermediate frequency simulate signal generates passage; Described signal generates through star and the cumulative parameter of ocean reflection and the power control code that passage receives input, and described cumulative parameter comprises pseudo-code code ring parameter and carrier wave ring parameter; And obtain the phase place of carrier wave meter and code table according to cumulative calculation of parameter, tabling look-up in pseudo-code code table and carrier wave meter according to the phase place that calculates obtains carrier wave and code; Carrier wave and the pseudo-code that utilization obtains modulated, filtering, close after the road, multiplies each other with the power control code and carries out the power adjustment and obtain the digital intermediate frequency simulate signal.

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