CN104237901A - Satellite navigation and communication integrated method and system - Google Patents

Abstract

The invention discloses a satellite navigation and communication integrated method and system. The method includes the steps of S1, subjecting a navigation signal and a communication signal to multi-carrier modulation to obtain a modulated signal which is then sent out; S2, receiving the modulated signal and demodulating the modulated signal, and acquiring the communication signal and the navigation signal. The system comprises a signal processing and transmitting module and a signal receiving and processing module; the signal processing and transmitting module is used for subjecting the navigation signal and the communication signal to multi-carrier modulation to acquire the modulated signal which is then sent out; the signal receiving and processing module is used for receiving the modulated signal and demodulating the modulated signal to obtain the communication signal. The method and the system according to the technical scheme have the advantages that system transmission efficiency and spectral utilization rate can be increased, and anti-interference performance of the system can be enhanced.

Description

Satellite navigation communicating integral method and system

Technical field

The present invention relates to technical field of satellite communication, particularly relate to a kind of satellite navigation communicating integral method and system.

Background technology

Technique of Satellite Navigation and Positioning is applied very extensive of today, existing GPS (Global Position System) comprises the GPS (Global Positioning System) of the U.S., the Big Dipper, the Russian GLONASS (GLObal Navigation Satellite System) of China, the Galileo system in Europe.And existing GPS (Global Position System) such as GPS only has the ability sending navigation message, do not possess the function of data communication.Satellite communication function in existing navigational system is also confined to short data communication always, can only meet the transmission of simple information.And communication system of the prior art is separated with navigational system, the communication performance that fixedly makes of communication resource configuration cannot promote always, also cannot solve the problems such as communication channel deficiency and navigation channels redundancy, become the bottleneck that satellite communication capabilities promotes.Meanwhile, the mentality of designing that existing navigational communications separates, causes navigation signal to be not easy hidden, is very easily attacked.

How the navigation of satellite is combined with communication function and realize distributing rationally of resource, and realize high-quality communication between satellite and ground and navigation with lower cost and hardware complexity.Become the problem that present stage needs solution badly.

Summary of the invention

The present invention is directed to the deficiencies in the prior art, propose and a kind ofly can improve the transfer efficiency of system and the satellite navigation communicating integral method and system of the availability of frequency spectrum.

A kind of satellite navigation communicating integral method, is characterized in that, comprise the following steps:

S1: navigation signal and signal of communication are carried out multi-carrier modulation by signal transacting and sending module, sends after obtaining modulation signal;

S2: Signal reception and processing module receive described modulation signal and carry out demodulation, obtain described signal of communication and navigation signal.

As prioritization scheme, the step of multi-carrier modulation described in step S1 is specially:

S101: spread spectrum is carried out, chnnel coding to navigation signal and signal of communication, and carry out frequency spectrum resource distribution by default spectrum allocation may mode, obtain rough handling signal;

S102: carry out filter shape to described preliminary modulation signal, obtains filtering processing signals;

S103: carry out IFFT conversion to described filtering processing signals, obtains IFFT processing signals on sub-carriers by described filtering processing signals modulation;

S104: parallel serial conversion is carried out to described IFFT processing signals, obtains described modulation signal;

Step S2 also comprises matched filtering step after carrying out demodulation.

As prioritization scheme, described modulation signal is modulated on several subcarriers, thus transmits in a multiple carrier channel.

As prioritization scheme, described modulation signal transmits in multiple carrier channel, and described multiple carrier channel comprises navigation subchannel and communications sub-channel;

Described navigation subchannel comprises even number navigation channels, a corresponding subcarrier in each described navigation channels; Described communications sub-channel comprises several communication channels, a corresponding subcarrier in each described communication channel;

Described navigation signal is transmitted in navigation subchannel by described subcarrier;

Described signal of communication is transmitted in communications sub-channel by described subcarrier.

As prioritization scheme, described default spectrum allocation may mode comprises described navigation subchannel different described subcarrier corresponding to communications sub-channel.

A kind of satellite navigation communication integrated system, is characterized in that, comprising:

Signal transacting and sending module: for navigation signal and signal of communication are carried out multi-carrier modulation, send after obtaining modulation signal;

Signal reception and processing module: for receiving described modulation signal and carrying out demodulation, obtain described signal of communication and navigation signal.

As prioritization scheme, described modulation signal transmits in multiple carrier channel, and described multiple carrier channel comprises navigation subchannel and communications sub-channel;

Described navigation subchannel comprises even number navigation channels, a corresponding subcarrier in each described navigation channels; Described communications sub-channel comprises several communication channels, a corresponding subcarrier in each described communication channel;

Described navigation signal is transmitted in navigation subchannel by described subcarrier;

Described signal of communication is transmitted in communications sub-channel by described subcarrier.

Compared with prior art, the present invention has following beneficial effect:

The invention provides the navigational communications integral system that a kind of navigation, communication performance are comparatively balanced, the scenes such as navigational system backup, emergency communication, the reception of navigation signal subsidiary communications can be applied to.The Signal transmissions scheme that technical solution of the present invention proposes is by specially designed parallel multi-carrier modulation technology, navigation channels and communication channel are unified, under the prerequisite not changing time-frequency domain structure, enable navigation subchannel and communications sub-channel coexist in a system, thus improve the availability of frequency spectrum, reduce the signal rate of every road carrier wave, make the cost on every road and hardware complexity be obtained for reduction.The flexible spectrum of navigation subchannel and communications sub-channel divides the multiple demand being equipped with and meeting system, improves the interference free performance of system.Satellite in this system is used as data communication at ordinary times, and can not normally use once other Navsats are under attack, at this moment satellite is as the star for subsequent use of Navsat, plays navigation function by launching navigation signal.And owing to not only comprising signal of communication but also comprise navigation signal in satellite-signal, thus can hidden navigation signal preferably, make it be not easy to be interfered.Easily extensible range of application of the present invention, and can be applicable to single carrier or multicarrier transmission systems.

Accompanying drawing explanation

Fig. 1 is that the FMT of navigation signal and signal of communication modulates block diagram;

Fig. 2 is the FMT demodulation block diagram of navigation signal and signal of communication;

Fig. 3 is navigation data process block diagram;

Fig. 4 is a kind of spectrum allocation may mode of navigation subchannel and communications sub-channel;

Fig. 5 is that navigation signal relevant treatment realizes block diagram;

Embodiment

Below in conjunction with accompanying drawing, in the mode of specific embodiment, the present invention is described in detail.Following examples will contribute to those skilled in the art and understand the present invention further, but not limit the present invention in any form.It should be pointed out that to those skilled in the art, without departing from the inventive concept of the premise, some distortion and improvement can also be made.These all belong to protection scope of the present invention.

A kind of satellite navigation communicating integral method, is characterized in that, comprise the following steps:

S1: navigation signal and signal of communication are carried out multi-carrier modulation by signal transacting and sending module, sends after obtaining modulation signal;

S2: Signal reception and processing module receive described modulation signal and carry out demodulation, obtain described signal of communication and navigation signal.

As prioritization scheme, the step of multi-carrier modulation described in step S1 is specially:

S101: spread spectrum is carried out, chnnel coding to navigation signal and signal of communication, and carry out frequency spectrum resource distribution by default spectrum allocation may mode, obtain rough handling signal;

S102: carry out filter shape to described preliminary modulation signal, obtains filtering processing signals;

S103: carry out IFFT conversion to described filtering processing signals, obtains IFFT processing signals on sub-carriers by described filtering processing signals modulation;

S104: parallel serial conversion is carried out to described IFFT processing signals, obtains described modulation signal;

Step S2 also comprises matched filtering step after carrying out demodulation.

As prioritization scheme, described modulation signal is modulated on several subcarriers, thus transmits in a multiple carrier channel.

As prioritization scheme, described modulation signal transmits in multiple carrier channel, and described multiple carrier channel comprises navigation subchannel and communications sub-channel;

Described navigation subchannel comprises even number navigation channels, a corresponding subcarrier in each described navigation channels; Described communications sub-channel comprises several communication channels, a corresponding subcarrier in each described communication channel;

Described navigation signal is transmitted in navigation subchannel by described subcarrier;

Described signal of communication is transmitted in communications sub-channel by described subcarrier.

As prioritization scheme, described default spectrum allocation may mode comprises described navigation subchannel different described subcarrier corresponding to communications sub-channel.

A kind of satellite navigation communication integrated system, is characterized in that, comprising:

Signal transacting and sending module: for navigation signal and signal of communication are carried out multi-carrier modulation, send after obtaining modulation signal;

Signal reception and processing module: for receiving described modulation signal and carrying out demodulation, obtain described signal of communication and navigation signal.

As prioritization scheme, described modulation signal transmits in multiple carrier channel, and described multiple carrier channel comprises navigation subchannel and communications sub-channel;

Described navigation subchannel comprises even number navigation channels, a corresponding subcarrier in each described navigation channels; Described communications sub-channel comprises several communication channels, a corresponding subcarrier in each described communication channel;

Described navigation signal is transmitted in navigation subchannel by described subcarrier;

Described signal of communication is transmitted in communications sub-channel by described subcarrier.

Channel described in the present embodiment represents the frequency bandwidth shared by Signal transmissions, and the subchannel that wherein navigates is corresponding with the subcarrier place frequency band of transmission navigation signal, and communications sub-channel is corresponding with the subcarrier place frequency band of transmit communications signals, as shown in Figure 4.

Multi-carrier modulation technology is exactly by transmitting data in parallel on M sub-channels, M when making the symbol duration in every sub-channels expand to single carrier transmission doubly, thus effectively reduce the intersymbol interference (ISI caused by delay spread, Inter-symbol Interference), greatly reduce the bit error rate, also reduce rate request and the hardware complexity of data processing simultaneously.

The sub-channel spectra non-overlapping copies of filtering multitone modulation (FMT, Filtered Multitone Modulation) system, each subchannel has very high spectrum containment, insensitive to system frequency deviation.The sub-channel spectra of FMT system non-overlapping copies makes interchannel interference in Received signal strength (ICI, Inter channel Interference) to ignore, and makes system obtain good anti-ICI performance, and is convenient to the management of frequency spectrum.Realizing in structure, FMT can use inverse discrete fourier transform (IDFT, Inversed Discrete Fourier Transform) and Fourier transform (DFT, Discrete Fourier Transform) effective implemention.

The signal transacting of the present embodiment and sending module adopt FMT to modulate to navigation signal and signal of communication unification, and FMT modulated process as shown in Figure 1.

As shown in Figure 1, also comprise matched filtering step before carrying out FMT modulation, the matched filtering module of the present embodiment is square root raised cosine (SRRC) wave filter.

Median filter design of the present invention is very crucial.In general, the restriction of wave filter demand fulfillment " perfect reconstruction " traditionally, to ensure that the ISI in transmission can not affect performance.The present embodiment adopts the wave filter of brachymemma, while the wave filter that multiple subcarrier is identical by frequency-domain structure being sent by bank of filters technology, filter length effectively can be avoided to be subject to the restriction of frequency domain process complexity, to ensure that the ISI in Signal transmissions can not affect performance.Further, what the present embodiment adopted is the root raised cosine nyquist filter of brachymemma.Choose T ₀for symbol period, then f ₀=1/2T ₀for nyquist frequency, H (f) is frequency response.By the character of SRRC, if receiving end need recover frequency-region signal, then a subcarriers frequency spectrum need comprise roll-off shaping.Getting rolloff-factor is ρ, then have frequency domain shock response to be:

$\left|H\left(f\right)\right|=\left\{\begin{array}{c}1\mathrm{if}\left|f\right|\≤(1-\mathrm{\ρ})/2T_0\\ \frac{1}{\sqrt{2}}\sqrt{1-\sin \frac{\mathrm{\π}}{\mathrm{\ρ}}(f{T}_0-\frac{1}{2})}\\ 0\mathrm{otherwise}\end{array}(1-\mathrm{\ρ})/2T_0\≤\left|f\right|\≤(1+\mathrm{\ρ})/2T_0\right.$

F is obtained by SRRC filter property ₁=(1+ ρ) f ₀for frequency domain main lobe width, then in order to its main lobe width energetic, need to choose suitable sampling rate.

In a system, usual sample frequency f _sfirst determined.Then, due to f ₁=(1+ ρ) f ₀, then f is had _s/ f ₀=(1+ ρ) f _s/ f ₁.Integer M is chosen by suitable ₀=f _s/ f ₀, M ₁=f _s/ f ₁, just can obtain the parameter of whole system.Wherein, M ₀be the sampled point number in a symbol, M ₁it is a mark relevant to filter frequency domain.

In the present embodiment, navigation signal adopts SRRC+QPSK signal.Therefore, the subsignal that navigates can be expressed as:

$x\left(i\right)=\underset{k}{\mathrm{\Σ}}a\left(m\right)c_{\mathrm{\Σ}}\left(i\right)e^{j2\mathrm{\πk}/M_1}$

Wherein, $c_{\mathrm{\Σ}}\left(i\right)=\left(\underset{n=0}{\overset{2045}{\mathrm{\Σ}}}c(n,k)g_{\mathrm{SRRC}}(i-n{T}_c)\right).$

Navigation signal a (m) is modulation signal, and m is the symbol intervals of navigation signal, and c is CDMA spreading code, and spreading code as shown in Figure 1 is c ₁(t), T _cfor CDMA spreading code symbol width, wherein spreading ratio is 2046, and namely have 2046 code elements in each symbol, g represents SRRC wave filter.K in navigation subsignal expression formula has two values, namely represents two subcarriers at x (i) band occupancy two ends as shown in Figure 4.A in Fig. 1 _rt () is navigation signal.

Communications sub-channel and navigation subchannel are carried out FMT modulation, a in Fig. 1 by the present embodiment _ct () is signal of communication.

In time domain, signal of communication a _ct () carries out arranging and transmitting according to rule as shown in Figure 4.

On frequency domain, the FMT subcarrier of signal of communication can also regularly be divided into several frequency sub-band, and each communicator frequency range can the identical or different communication data channel of independent bearing, and communicator frequency range is the minimum frequency domain resource that can use.

When satellite navigation communication integrated system is applied to data communication, the subcarrier of communication channel FMT Frame is assigned to each communication customer end.Each communication customer end carries out signal frame generation according to pre-assigned subcarrier, then the signal of communication each subcarrier transmitted can be write as:

Wherein, g _sRRC(i-M ₀m) be above-described SRRC wave filter, k is the subcarrier number that frequency domain takies, and i is time-domain sampling piont mark.

Be exactly more than the process of the signal transacting of satellite navigation communication integrated system and the navigation signal of sending module and signal of communication, modulated process.

Receive the modulation signal of form as shown in Figure 4 at communication customer end after, first to the FMT demodulation step that modulation signal carries out as shown in Figure 2.First carry out serial to parallel conversion, then carry out Fourier transform (FFT), finally carry out matched filtering, obtain original navigation signal and signal of communication.After obtaining navigation signal, further navigation data in navigation signal caught, follow the tracks of, synchronous operation steps, and then resolve navigation message.

Matched filtering as shown in Figure 3 mainly designs the wave filter that SRRC wave filter used when modulating with FMT matches.

Wherein catch step and mainly comprise yard correlation step and Doppler's detecting step, as Fig. 3.

Tracing process mainly comprises carrier track and C/A code tracking.Be the present embodiment carrier track step used below.

When navigation signal is correlated with, input two symmetrical carrier waves (I road and Q road) as Fig. 5, this locality reproduction signal of in-phase branch (I road) can be expressed as

$x_{L,n}^I\left(n\right)=(g_n^I\left(t\right)+g_{-n}^I\left(t\right))\cos (2\mathrm{\π}{\hat{f}}_{c}t+\widehat{\mathrm{\θ}})-(g_n^Q\left(t\right)+g_{-n}^Q\left(t\right))\sin (2\mathrm{\π}{\hat{f}}_{c}t+\widehat{\mathrm{\θ}})$

$g_n^I\left(t\right)=A_{n}c(t-\mathrm{\Δ\τ}).\cos \left[2\mathrm{\π}{f}_n(t-\mathrm{\Δ\τ})\right]$

$g_n^Q\left(t\right)=A_{n}c(t-\mathrm{\Δ\τ}).\sin \left[2\mathrm{\π}{f}_n(t-\mathrm{\Δ\τ})\right]$

Wherein, A _nfor range value, Δ τ is time delay, f _nfor carrier frequency, for the IF-FRE estimated. for the phase place of the carrier wave of estimation.

This locality reproduction signal of quadrature branch (Q road) can be expressed as

$x_{L,n}^Q\left(n\right)=-(g_n^I\left(t\right)+g_{-n}^I\left(t\right))\cos (2\mathrm{\π}{\hat{f}}_{c}t+\widehat{\mathrm{\θ}})-(g_n^Q\left(t\right)-g_{-n}^Q\left(t\right))\sin (2\mathrm{\π}{\hat{f}}_{c}t+\widehat{\mathrm{\θ}})$

Then by X (t) respectively with with carry out relevant can obtaining

$s_n^I\left[k\right]\≈A_n^2.d_n^k.R_{\mathrm{cc}}\left(\mathrm{\Δ\τ}\right).\cos \left(2\mathrm{\π}{f}_n\mathrm{\Δ\τ}\right).\sin c\left(\mathrm{\π\Δf}{T}_R\right).\sin (\mathrm{\π\Δf}2k{T}_R+\mathrm{\Δ\θ})$

$s_n^Q\left[k\right]\≈A_n^2.d_n^k.R_{\mathrm{cc}}\left(\mathrm{\Δ\τ}\right).\cos \left(2\mathrm{\π}{f}_n\mathrm{\Δ\τ}\right).\sin c\left(\mathrm{\π\Δf}{T}_R\right).\cos (\mathrm{\π\Δf}2k{T}_R+\mathrm{\Δ\θ})$

In formula, Section 3 is code relevant peaks, and the last correlated results according to obtaining can obtain the output of phaselocked loop and FLL, thus obtains the precision needing estimation.

Complete tracing process, realizing synchronously further, we just can resolve navigation message, obtain the pseudo-range information of satellite to ground surface end.After obtaining multiple (four and more than) satellite to the pseudo-range information of ground surface end, we just can solve the position coordinates of ground surface end, complete location.

The above is only the preferred embodiment of the present invention; it should be pointed out that for those skilled in the art, under the prerequisite not departing from the technology of the present invention principle; can also make some improvements and modifications, these improvements and modifications also should be considered as protection scope of the present invention.

Claims (7)

1. a satellite navigation communicating integral method, is characterized in that, comprises the following steps:

S1: navigation signal and signal of communication are carried out multi-carrier modulation by signal transacting and sending module, sends after obtaining modulation signal;

S2: Signal reception and processing module receive described modulation signal and carry out demodulation, obtain described signal of communication and navigation signal.

2. method according to claim 1, is characterized in that,

The step of multi-carrier modulation described in step S1 is specially:

S101: spread spectrum is carried out, chnnel coding to navigation signal and signal of communication, and carry out frequency spectrum resource distribution by default spectrum allocation may mode, obtain rough handling signal;

S102: carry out filter shape to described preliminary modulation signal, obtains filtering processing signals;

S103: carry out IFFT conversion to described filtering processing signals, obtains IFFT processing signals on sub-carriers by described filtering processing signals modulation;

S104: parallel serial conversion is carried out to described IFFT processing signals, obtains described modulation signal;

Step S2 also comprises matched filtering step after carrying out demodulation.

3. method according to claim 1, is characterized in that,

Described modulation signal is modulated on several subcarriers, thus transmits in a multiple carrier channel.

4. method according to claim 3, is characterized in that, described modulation signal transmits in multiple carrier channel, and described multiple carrier channel comprises navigation subchannel and communications sub-channel;

Described navigation subchannel comprises even number navigation channels, a corresponding subcarrier in each described navigation channels; Described communications sub-channel comprises several communication channels, a corresponding subcarrier in each described communication channel;

Described navigation signal is transmitted in navigation subchannel by described subcarrier;

Described signal of communication is transmitted in communications sub-channel by described subcarrier.

5. method according to claim 4, is characterized in that,

Described default spectrum allocation may mode comprises described navigation subchannel different described subcarrier corresponding to communications sub-channel.

6. a satellite navigation communication integrated system, is characterized in that, comprising:

Signal transacting and sending module: for navigation signal and signal of communication are carried out multi-carrier modulation, send after obtaining modulation signal; Signal reception and processing module: for receiving described modulation signal and carrying out demodulation, obtain described signal of communication and navigation signal.

7. a kind of satellite navigation communication integrated system according to claim 6, it is characterized in that, described modulation signal transmits in multiple carrier channel, and described multiple carrier channel comprises navigation subchannel and communications sub-channel;

Described navigation subchannel comprises even number navigation channels, a corresponding subcarrier in each described navigation channels; Described communications sub-channel comprises several communication channels, a corresponding subcarrier in each described communication channel;

Described navigation signal is transmitted in navigation subchannel by described subcarrier;

Described signal of communication is transmitted in communications sub-channel by described subcarrier.