CN105137455A

CN105137455A - Offset carrier wave modulation method based on sine pulse three-grade symbol

Info

Publication number: CN105137455A
Application number: CN201510519864.9A
Authority: CN
Inventors: 赵旦峰; 孙岩博; 薛睿; 曹庆铭; 孙兵兵; 吕雪
Original assignee: Harbin Engineering University
Current assignee: Harbin Engineering University
Priority date: 2015-08-23
Filing date: 2015-08-23
Publication date: 2015-12-09

Abstract

The invention discloses an offset carrier wave modulation method based on a sine pulse three-grade symbol, comprising steps of determining a spectrum spreading code frequency fc, a subcarrier frequency fsc, a sine pulse time width duty ratio RhO and a sine or cosine phase subcarrier modulation method, constructing a sine or cosine phase subcarrier signal based on a sine pulse three-grade symbol, utilizing a pseudo random sequence to perform spectrum spreading on navigation signals, performing modulation on subcarriers, and performing carrier modulation of an orthogonal branch on obtained signals. The signals produced through the method can flexibly regulate the splitting degree of the main lobe and the sidelobe of the signal power spectrum to enable the navigation signal to have a better code tracing function, functions of resisting interference and multi-diamter, and the function being compatible with the other system signals.

Description

A three-level symbol-offset carrier modulation method based on sinusoidal pulses

技术领域technical field

本发明涉及一种卫星导航系统信号的实现方法，具体涉及一种基于正弦脉冲三级符号偏移载波调制方法。The invention relates to a method for realizing a signal of a satellite navigation system, in particular to a method for modulating a carrier wave based on a sinusoidal pulse three-level symbol offset.

背景技术Background technique

导航调制信号波形是导航信号体制设计中的关键环节，信号波形通过影响导航信号的自相关函数和功率谱，进而影响导航系统的性能。为了使多种信号可以更好地共享全球导航卫星系统(GlobalNavigationSatelliteSystem,GNSS)的有限频段，同时进一步提高信号的测距精度及抗干扰性能，新的信号调制方式不断呈现。二进制偏移载波(BinaryOffsetCarrier,BOC(n,m))是一种能够满足上述要求的新型调制方式，其中扩频码频率为m×1.023MHz，子载波频率为n×1.023MHz，其实现方法详见文献Betz.J,“TheOffsetCarrierModulationforGPSModernization,”IONNTM,SanDiego,CA,January25-27,1999.The navigation modulation signal waveform is a key link in the design of the navigation signal system. The signal waveform affects the performance of the navigation system by affecting the autocorrelation function and power spectrum of the navigation signal. In order to enable multiple signals to better share the limited frequency band of the Global Navigation Satellite System (GNSS), and to further improve the ranging accuracy and anti-interference performance of the signal, new signal modulation methods are constantly emerging. Binary Offset Carrier (Binary Offset Carrier, BOC(n, m)) is a new modulation method that can meet the above requirements, in which the frequency of the spreading code is m×1.023MHz, and the frequency of the subcarrier is n×1.023MHz. See literature Betz.J, "The Offset Carrier Modulation for GPS Modernization," IONNTM, SanDiego, CA, January 25-27, 1999.

Betz.J在文献“BinaryOffsetCarrierModulationsforRadionavigation,”Navigation:JournaloftheInstituteofNavigation,vol.48,No.4,Winter2001-2002.中指出，在同一波段、占用相同带宽以及对信号发射器和接收机做同样简单设计的条件下，BOC调制信号的性能比BPSK调制信号更优越。BOC调制目前已经广泛应用于GPS、Galileo和Compass等全球卫星导航系统中。Betz.J pointed out in the document "BinaryOffsetCarrierModulationsforRadionavigation," Navigation: Journal of the Institute of Navigation, vol.48, No.4, Winter2001-2002. Under the conditions of the same band, occupying the same bandwidth and the same simple design of the signal transmitter and receiver , the performance of BOC modulated signal is superior to that of BPSK modulated signal. BOC modulation has been widely used in global satellite navigation systems such as GPS, Galileo and Compass.

随着卫星导航信号数量的不断增加，频谱资源紧张，在有限带宽下提高信号性能以及减小相邻信号间的干扰成为目前的研究重点。文章中给出的BOC调制方法会带来带外大幅度旁瓣使功放效率降低，且信号的码跟踪性能、抗多径和抗干扰能力仍不够理想，因此本发明提出一种基于正弦脉冲三级符号偏移载波调制方法(SinusoidalThree-levelsOffsetCarrier,STOC(n,m,ρ))，其中子载波信号可取值为±1和0，且±1信号波形由正弦脉冲表示，该方法可以灵活调整子载波信号波形码片时间占空比，为导航信号的设计提供了更多的选择，并通过所选适当的参数，可以灵活调节信号功率谱的主瓣及旁瓣的分裂程度，使得导航信号具有良好的码跟踪性能、抗干扰和抗多径能力、与其它系统信号兼容能力，对于提升卫星导航系统的导航和定位性能有重要的意义，同时也为我国未来Compass卫星导航系统的信号波形设计提供了一个新的选择。With the increasing number of satellite navigation signals and the shortage of spectrum resources, improving signal performance and reducing interference between adjacent signals under limited bandwidth have become the focus of current research. The BOC modulation method given in the article will bring out-of-band large-amplitude sidelobes to reduce the efficiency of the power amplifier, and the code tracking performance, anti-multipath and anti-interference ability of the signal are still not ideal, so the present invention proposes a three-phase signal based on sinusoidal pulse Level symbol offset carrier modulation method (SinusoidalThree-levelsOffsetCarrier, STOC(n,m,ρ)), in which the subcarrier signal can take values of ±1 and 0, and the ±1 signal waveform is represented by a sinusoidal pulse, this method can be flexibly adjusted The chip time duty cycle of the subcarrier signal waveform provides more choices for the design of the navigation signal, and by selecting appropriate parameters, the splitting degree of the main lobe and the side lobe of the signal power spectrum can be flexibly adjusted, so that the navigation signal It has good code tracking performance, anti-interference and anti-multipath capabilities, and signal compatibility with other systems, which is of great significance for improving the navigation and positioning performance of satellite navigation systems, and also for the signal waveform design of my country's future Compass satellite navigation system A new option is provided.

发明内容Contents of the invention

本发明的目的在于提出一种可以灵活调节信号功率谱的主瓣及旁瓣的分裂程度，使得导航信号具有良好的码跟踪性能、抗干扰和抗多径能力、与其它系统信号兼容能力的基于正弦脉冲三级符号偏移载波调制方法。The purpose of the present invention is to propose a kind of split degree that can flexibly adjust the main lobe and side lobe of signal power spectrum, make navigation signal have good code tracking performance, anti-jamming and anti-multipath ability, compatible with other system signal based on A three-level symbol-offset carrier modulation method for sinusoidal pulses.

本发明的目的是这样实现的：The purpose of the present invention is achieved like this:

(1)首先确定扩频码周期T_c，子载波周期T_sc，正弦脉冲时间宽度占空比ρ，正弦或余弦相位子载波调制方式，构造出一种基于正弦脉冲三级符号正弦或余弦相位子载波信号，具体表示为：(1) First determine the spreading code period T _c , subcarrier period T _sc , sine pulse time width duty ratio ρ, sine or cosine phase subcarrier modulation mode, and construct a three-level symbol sine or cosine phase based on sine pulse The bit carrier signal is specifically expressed as:

基于正弦脉冲三级符号正弦相位子载波信号X_S-sub(t,ρ)为：Based on the sinusoidal pulse three-level symbol sinusoidal phase subcarrier signal X _S-sub (t, ρ) is:

${X x}_{S S - - s the s u u b b} ((t t,, ρ ρ)) = = s the s i i g g n no ((s the s i i n no ((22 {πf πf}_{s the s c c} t t)))) \times \times {Σ Σ}_{i i = = 00}^{+ + ∞ ∞} {P P}_{\frac{{T T}_{s the s c c}}{22}} ((t t - - i i \frac{{T T}_{s the s c c}}{22},, ρ ρ)),, t t > > 00;;$

基于正弦脉冲三级符号余弦相位子载波信号X_C-sub(t,ρ)为：Based on the sinusoidal pulse three-level symbol cosine phase subcarrier signal X _C-sub (t, ρ) is:

${X x}_{C C - - s the s u u b b} ((t t,, ρ ρ)) = = s the s i i g g n no ((c c o o s the s ((22 {πf πf}_{s the s c c} t t)))) \times \times {Σ Σ}_{i i = = 00}^{+ + ∞ ∞} {P P}_{\frac{{T T}_{s the s c c}}{44}} ((t t - - i i \frac{{T T}_{s the s c c}}{44},, ρ ρ)),, t t > > 00;;$

其中P_τ(t,ρ)是时间宽度为ρτ的正弦脉冲波形，即sign(t)为符号函数，即 $s i g n (t) = {\begin{matrix} 1, & t > 0 \\ - 1, & t < 0 \end{matrix};$ where P _τ (t,ρ) is a sinusoidal pulse waveform with a time width of ρτ, namely sign(t) is a sign function, namely $the s i g no (t) = {\begin{matrix} 1, & t > 0 \\ - 1, & t < 0 \end{matrix};$

(2)根据确定的扩频码周期T_c，子载波周期T_sc，利用伪随机序列对导航信号进行扩频，然后将得到的扩频信号与步骤(1)所确定的正弦或余弦相位子载波信号进行时域相乘，得到一种基于正弦脉冲三级符号正弦或余弦相位偏移载波基带调制信号，具体表示为：(2) According to the determined spread spectrum code cycle T _c , the subcarrier cycle T _sc , utilize the pseudo-random sequence to spread the navigation signal, and then combine the obtained spread spectrum signal with the determined sine or cosine phase of step (1) The carrier signal is multiplied in the time domain to obtain a baseband modulation signal based on the sinusoidal pulse three-level symbol sine or cosine phase offset carrier, specifically expressed as:

基于正弦脉冲三级符号正弦相位偏移载波基带调制信号S_{STOCs(n,m,ρ)}(t)为：Based on the sinusoidal pulse three-level symbol sinusoidal phase offset carrier baseband modulation signal S _{STOCs(n,m,ρ)} (t) is:

${S S}_{S S T T O o C C s the s ((n no,, m m,, ρ ρ))} ((t t)) = = d d ((t t)) {Σ Σ}_{l l = = 00}^{L L - - 11} {a a}_{l l} r r e e c c t t ((t t - - {lT lT}_{c c})) \times \times {X x}_{S S - - s the s u u b b} ((t t,, ρ ρ)),, t t > > 00;;$

基于正弦脉冲三级符号余弦相位偏移载波基带调制信号S_{STOCc(n,m,ρ)}(t)为：Based on the sinusoidal pulse three-level symbol cosine phase offset carrier baseband modulation signal S _{STOCc(n,m,ρ)} (t) is:

${S S}_{S S T T O o C C c c ((n no,, m m,, ρ ρ))} ((t t)) = = d d ((t t)) {Σ Σ}_{l l = = 00}^{L L - - 11} {a a}_{l l} r r e e c c t t ((t t - - {lT lT}_{c c})) \times \times {X x}_{C C - - s the s u u b b} ((t t,, ρ ρ)),, t t > > 00;;$

其中d(t)为导航信号数据通道信息；a_l是伪随机扩频序列的第l个扩频码；L为伪随机序列的码片长度；rect(t)是矩形门函数，即或 $n = \frac{1}{T_{s c} \times 1.023 M H z}; m = \frac{f_{c}}{1.023 M H z}$ 或 $m = \frac{1}{T_{c} \times 1.023 M H z};$ Among them, d(t) is the navigation signal data channel information; a _l is the lth spreading code of the pseudo-random spreading sequence; L is the chip length of the pseudo-random sequence; rect(t) is the rectangular gate function, namely or $no = \frac{1}{T_{the s c} \times 1.023 m h z}; m = \frac{f_{c}}{1.023 m h z}$ or $m = \frac{1}{T_{c} \times 1.023 m h z};$

(3)将步骤(2)所述的一种基于正弦脉冲三级符号正弦或余弦相位偏移载波基带调制信号进行正交支路的载波调制，得到基于正弦脉冲三级符号正弦或余弦相位偏移载波调制信号，具体表示为：(3) Carry out the carrier modulation of the quadrature branch based on the sine pulse three-level symbol sine or cosine phase offset carrier baseband modulation signal described in step (2), obtain based on the sinusoidal pulse three-level symbol sine or cosine phase offset Carrier shift modulation signal, specifically expressed as:

基于正弦脉冲三级符号正弦相位偏移载波调制信号M_{STOCs(n,m,ρ)}(t,ρ)为：Based on the sinusoidal pulse three-level symbol sinusoidal phase offset carrier modulation signal M _{STOCs(n,m,ρ)} (t,ρ) is:

$\begin{matrix} {M m}_{S S T T O o C C s the s ((n no,, m m,, ρ ρ))} ((t t,, ρ ρ)) = = [[d d ((t t)) {Σ Σ}_{l l = = 00}^{L L - - 11} {a a}_{l l} r r e e c c t t ((t t - - {lT lT}_{c c})) \times \times s the s i i g g n no ((sin sin ((22 {πf πf}_{s the s c c} t t)))) \times \times {Σ Σ}_{i i = = 00}^{+ + ∞ ∞} {P P}_{\frac{{T T}_{s the s c c}}{22}} ((t t - - i i \frac{{T T}_{s the s c c}}{22},, ρ ρ))]] cos cos ((22 {πf πf}_{c c a a r r} t t)) \\ + + [[p p ((t t)) {Σ Σ}_{k k = = 00}^{L L - - 11} {b b}_{k k} r r e e c c t t ((t t - - {kT kT}_{c c})) \times \times s the s i i g g n no ((sin sin ((22 {πf πf}_{s the s c c} t t)))) \times \times {Σ Σ}_{i i = = 00}^{+ + ∞ ∞} {P P}_{\frac{{T T}_{s the s c c}}{22}} ((t t - - i i \frac{{T T}_{s the s c c}}{22},, ρ ρ))]] sin sin ((22 {πf πf}_{c c a a r r} t t)) \end{matrix};;$

基于正弦脉冲三级符号余弦相位偏移载波调制信号M_{STOCc(n,m,ρ)}(t,ρ)为：The carrier modulation signal M _{STOCc(n,m,ρ)} (t,ρ) based on the three-level symbol cosine phase offset of the sine pulse is:

$\begin{matrix} {M m}_{S S T T O o C C c c ((n no,, m m,, ρ ρ))} ((t t,, ρ ρ)) = = [[d d ((t t)) {Σ Σ}_{l l = = 00}^{L L - - 11} {a a}_{l l} r r e e c c t t ((t t - - {lT lT}_{c c})) \times \times s the s i i g g n no ((cos cos ((22 {πf πf}_{s the s c c} t t)))) \times \times {Σ Σ}_{i i = = 00}^{+ + ∞ ∞} {P P}_{\frac{{T T}_{s the s c c}}{44}} ((t t - - i i \frac{{T T}_{s the s c c}}{44},, ρ ρ))]] cos cos ((22 {πf πf}_{c c a a r r} t t)) \\ + + [[p p ((t t)) {Σ Σ}_{k k = = 00}^{L L - - 11} {b b}_{k k} r r e e c c t t ((t t - - {kT kT}_{c c})) \times \times s the s i i g g n no ((cos cos ((22 {πf πf}_{s the s c c} t t)))) \times \times {Σ Σ}_{i i = = 00}^{+ + ∞ ∞} {P P}_{\frac{{T T}_{s the s c c}}{44}} ((t t - - i i \frac{{T T}_{s the s c c}}{44},, ρ ρ))]] sin sin ((22 {πf πf}_{c c a a r r} t t)) \end{matrix};;$

其中d(t)为导航信号数据通道信息；p(t)为导频通道信息，取值为全+1或-1；a_l是同相支路伪随机扩频序列的第l个扩频码；b_k是正交支路伪随机扩频序列的第k个扩频码；f_car是载波频率。Among them, d(t) is the navigation signal data channel information; p(t) is the pilot channel information, and the value is all +1 or -1; a _l is the lth spreading code of the pseudo-random spreading sequence of the in-phase branch ; b _k is the kth spreading code of the pseudo-random spreading sequence of the orthogonal branch; f _car is the carrier frequency.

(4)将步骤(3)中得到的基于正弦脉冲三级符号偏移载波调制信号进行导航信号的性能评估，若信号的码跟踪精度、抗多径和兼容性不满足所设计的导航系统性能需求及约束条件，则返回步骤(1)，重新确定扩频码周期T_c，子载波周期T_sc，正弦或余弦相位子载波调制方式，以及正弦脉冲时间宽度占空比ρ。(4) The performance evaluation of the navigation signal based on the sinusoidal pulse three-level symbol offset carrier modulation signal obtained in step (3), if the code tracking accuracy, anti-multipath and compatibility of the signal do not meet the designed navigation system performance Requirements and constraints, return to step (1), re-determine the spreading code period T _c , subcarrier period T _sc , sine or cosine phase subcarrier modulation mode, and sine pulse time width duty ratio ρ.

本发明还可以包括：The present invention may also include:

所述的扩频码频率f_c和子载波频率f_sc的取值为1.023MHz的整数倍。The values of the spreading code frequency f _c and the subcarrier frequency f _sc are integer multiples of 1.023 MHz.

所述的基于正弦脉冲三级符号正弦相位偏移载波基带调制信号功率谱密度G_{STOCs(n,m,ρ)}(f)为：The power spectral density G STOCs (n, m, ρ) (f) of the baseband modulated signal power spectral density G _{STOCs (n, m, ρ)} (f) based on the sinusoidal pulse three-level symbol sinusoidal phase offset carrier is:

所述的基于正弦脉冲三级符号余弦相位偏移载波基带调制信号功率谱密度G_{STOCc(n,m,ρ)}(f)为：The described power spectral density G _{STOCc (n, m, ρ)} (f) based on the sinusoidal pulse three-level symbol cosine phase offset carrier baseband modulation signal is:

其中h为调制指数，即 $h = \frac{2 f_{s c}}{f_{c}}$ 或 $h = \frac{2 n}{m} .$ where h is the modulation index, namely $h = \frac{2 f_{the s c}}{f_{c}}$ or $h = \frac{2 no}{m} .$

本发明的方法的主要特点如下：The main features of the method of the present invention are as follows:

(1)信号设计的灵活性高：灵活调整正弦脉冲码片时间占空比，为导航信号的设计提供了更多的选择，并通过所选适当的参数，可以灵活调节信号功率谱的主瓣及旁瓣的分裂程度。(1) The flexibility of signal design is high: the flexible adjustment of the duty cycle of the sine pulse chip provides more choices for the design of the navigation signal, and the main lobe of the signal power spectrum can be flexibly adjusted by selecting appropriate parameters and the degree of splitting of the side lobes.

(2)跟踪精度高：在接收机带宽内，本发明调制信号的功率谱具有分裂能力且幅值较大，在带宽受限的条件下，具有更高的Gabor带宽与较低的码跟踪误差。(2) High tracking accuracy: within the receiver bandwidth, the power spectrum of the modulated signal of the present invention has splitting ability and larger amplitude, and has higher Gabor bandwidth and lower code tracking error under the condition of limited bandwidth .

(3)抗多径能力强：本发明调制信号具有恒包络特性，特别适合于采用高效非线性放大器的功率和带宽均受限的卫星导航服务，其多径误差包络衰减的更快且幅度更低。(3) strong anti-multipath ability: the modulated signal of the present invention has constant envelope characteristic, is particularly suitable for the satellite navigation service that adopts the power of high-efficiency nonlinear amplifier and the bandwidth all to be limited, and its multipath error envelope attenuates faster and The magnitude is lower.

(4)兼容性高：本发明调制信号的功率谱旁瓣衰减速度更快且幅度更低，对同频段的其它导航信号干扰较小。(4) High compatibility: The power spectrum side lobe of the modulated signal of the present invention decays faster and has a lower amplitude, and has less interference with other navigation signals in the same frequency band.

附图说明Description of drawings

图1为STOC信号调制模型和实现方法流程图；Fig. 1 is a flow chart of STOC signal modulation model and implementation method;

图2为STOC信号子载波信号波形；Fig. 2 is STOC signal subcarrier signal waveform;

图3为STOC实施例信号在不同正弦脉冲时间占空比ρ下的功率谱密度；Fig. 3 is the power spectral density of the STOC embodiment signal under different sinusoidal pulse time duty ratios ρ;

图4为传统的BOC和本发明所提的STOC实施例信号的功率谱密度；Fig. 4 is the power spectral density of traditional BOC and the STOC embodiment signal that the present invention proposes;

图5为传统的BOC和本发明所提的STOC实施例信号的Gabor带宽；Fig. 5 is the Gabor bandwidth of the STOC embodiment signal of traditional BOC and the present invention;

图6为传统的BOC和本发明所提的STOC实施例信号的码跟踪精度；Fig. 6 is the code tracking precision of traditional BOC and the STOC embodiment signal that the present invention proposes;

图7为传统的BOC和本发明所提的STOC实施例信号的多径误差包络；Fig. 7 is traditional BOC and the multipath error envelope of the STOC embodiment signal that the present invention proposes;

图8为传统的BOC和本发明所提的STOC实施例信号的平均多径误差。Fig. 8 shows the average multipath error of signals of the traditional BOC and the STOC embodiment of the present invention.

具体实施方式Detailed ways

下面结合附图和实施例对本发明作进一步说明：Below in conjunction with accompanying drawing and embodiment the present invention will be further described:

图1和图2为本发明所提的STOC信号调制模型,实现方法流程图以及子载波信号波形，其中图1中的各符号的定义如下：Fig. 1 and Fig. 2 are the STOC signal modulation model that the present invention proposes, the implementation method flowchart and the subcarrier signal waveform, wherein the definition of each symbol in Fig. 1 is as follows:

d(t)：导航信号数据通道信息；d(t): navigation signal data channel information;

p(t)：导频通道信息；p(t): pilot channel information;

a_l：同相支路的伪随机扩频码序列；a _l : Pseudo-random spreading code sequence of the same-phase branch;

b_l：正交支路的伪随机扩频码序列；b _l : Pseudo-random spreading code sequence of the orthogonal branch;

rec(t)：矩形门函数；rec(t): rectangular gate function;

X_S-sub(t,ρ)：所述的一种基于正弦脉冲三级符号正弦相位子载波信号波形；X _S-sub (t, ρ): the described one based on the sinusoidal pulse three-level symbol sinusoidal phase subcarrier signal waveform;

X_C-sub(t,ρ)：所述的一种基于正弦脉冲三级符号余弦相位子载波信号波形；X _C-sub (t, ρ): said a cosine phase subcarrier signal waveform based on the sinusoidal pulse three-level symbol;

M_STOC(t,ρ)：所述的一种基于正弦脉冲三级符号偏移载波调制信号；M _STOC (t, ρ): said one based on the sinusoidal pulse three-level symbol offset carrier modulation signal;

f_c：扩频码频率；f _c : spreading code frequency;

f_car：载波频率；f _car : carrier frequency;

f_sc：子载波频率；f _sc : subcarrier frequency;

结合图1，本发明实现方法如下：In conjunction with Fig. 1, the implementation method of the present invention is as follows:

(1)首先确定扩频码频率f_c或扩频码周期T_c(频率和周期互为倒数可任意确定其中一个参数)，子载波频率f_sc或子载波周期T_sc，正弦脉冲时间宽度占空比ρ以及正弦或余弦相位子载波调制方式，构造出一种基于正弦脉冲三级符号正弦或余弦相位子载波信号，具体表示为：(1) First determine the spreading code frequency f _c or the spreading code period T _c (one of the parameters can be arbitrarily determined as the frequency and period are reciprocals of each other), the subcarrier frequency f _sc or the subcarrier period T _sc , and the sinusoidal pulse time width occupies The space ratio ρ and the sine or cosine phase subcarrier modulation method construct a sine or cosine phase subcarrier signal based on the sine pulse three-level symbol, which is specifically expressed as:

${X x}_{S S - - s the s u u b b} ((t t,, ρ ρ)) = = s the s i i g g n no ((sin sin ((22 {πf πf}_{s the s c c} t t)))) \times \times {Σ Σ}_{i i = = 00}^{+ + ∞ ∞} {P P}_{\frac{{T T}_{s the s c c}}{22}} ((t t - - i i \frac{{T T}_{s the s c c}}{22},, ρ ρ)),, t t > > 00;;$

(2)根据确定的扩频码频率f_c或扩频码周期T_c和子载波频率f_sc或子载波周期T_sc，利用伪随机序列对导航信号进行扩频，然后将得到的扩频信号与步骤(1)所确定的正弦或余弦相位子载波信号进行时域相乘，得到一种基于正弦脉冲三级符号正弦或余弦相位偏移载波基带调制信号，具体表示为：(2) According to the determined spread spectrum code frequency f _c or spread spectrum code period T _c and subcarrier frequency f _sc or subcarrier period T _sc , the navigation signal is spread by using a pseudo-random sequence, and then the obtained spread spectrum signal is combined with The sine or cosine phase subcarrier signals determined in step (1) are multiplied in the time domain to obtain a sine or cosine phase offset carrier baseband modulation signal based on the sine pulse three-level symbol, which is specifically expressed as:

$\begin{matrix} {M m}_{S S T T O o C C c c ((n no,, m m,, ρ ρ))} ((t t,, ρ ρ)) = = [[d d ((t t)) {Σ Σ}_{l l = = 00}^{L L - - 11} {a a}_{l l} r r e e c c t t ((t t - - {lT lT}_{c c})) \times \times s the s i i g g n no ((cos cos ((22 {πf πf}_{s the s c c} t t)))) \times \times {Σ Σ}_{i i = = 00}^{+ + ∞ ∞} {P P}_{\frac{{T T}_{s the s c c}}{44}} ((t t - - i i \frac{{T T}_{s the s c c}}{44},, ρ ρ))]] cos cos ((22 {πf πf}_{c c a a r r} t t)) \\ + + [[p p ((t t)) {Σ Σ}_{k k = = 00}^{L L - - 11} {b b}_{k k} r r e e c c t t ((t t - - {kT kT}_{c c})) \times \times s the s i i g g n no ((sin sin ((22 {πf πf}_{s the s c c} t t)))) \times \times {Σ Σ}_{i i = = 00}^{+ + ∞ ∞} {P P}_{\frac{{T T}_{s the s c c}}{44}} ((t t - - i i \frac{{T T}_{s the s c c}}{44},, ρ ρ))]] sin sin ((22 {πf πf}_{c c a a r r} t t)) \end{matrix};;$

(4)将步骤(3)中得到的基于正弦脉冲三级符号偏移载波调制信号进行导航信号的性能评估，若信号的码跟踪精度、抗多径和兼容性不满足所设计的导航系统性能需求及约束条件，则返回步骤(1)，重新确定扩频码频率f_c或扩频码周期T_c，子载波频率f_sc或子载波周期T_sc，正弦或余弦相位子载波调制方式，以及正弦脉冲时间宽度占空比ρ。(4) The performance evaluation of the navigation signal based on the sinusoidal pulse three-level symbol offset carrier modulation signal obtained in step (3), if the code tracking accuracy, anti-multipath and compatibility of the signal do not meet the designed navigation system performance Requirements and constraints, then return to step (1), re-determine the spreading code frequency f _c or spreading code period T _c , subcarrier frequency f _sc or subcarrier period T _sc , sine or cosine phase subcarrier modulation mode, and Sine pulse time width duty cycle ρ.

其中h为调制指数，即 $h = \frac{2 f_{s c}}{f_{c}}$ 或 $h = \frac{2 n}{m}$ where h is the modulation index, namely $h = \frac{2 f_{the s c}}{f_{c}}$ or $h = \frac{2 no}{m}$

图3为本发明所提的STOC实施例信号在不同正弦脉冲时间宽度占空比ρ下的功率谱密度，由图3可知，通过改变正弦脉冲时间宽度占空比ρ，STOC信号能够灵活调节信号功率谱主瓣及旁瓣的分裂程度，且随着ρ的增加，信号功率谱主瓣能量更加集中同时旁瓣衰减速度更快，这无疑提高了导航信号设计的灵活度，使其能够更好的与现有信号兼容，为我国未来Compass卫星导航系统的信号波形设计提供了一个新的选择。Fig. 3 is the power spectral density of the STOC embodiment signal proposed by the present invention under different sinusoidal pulse time width duty ratio ρ, as can be seen from Fig. 3, by changing the sinusoidal pulse time width duty ratio ρ, the STOC signal can flexibly adjust the signal The degree of splitting of the main lobe and side lobe of the power spectrum, and with the increase of ρ, the main lobe energy of the signal power spectrum is more concentrated and the side lobe attenuation speed is faster, which undoubtedly improves the flexibility of navigation signal design and enables it to better Compatible with existing signals, it provides a new choice for the signal waveform design of Compass satellite navigation system in my country in the future.

图4为传统的BOC和本发明所提的STOC实施例信号的功率谱密度，其中STOCs(5,2,0.9)信号表现出较高的频谱效能。同时STOCs(5,2,0.9)在±10MHz附近，较传统的BOCs(5,2)信号具有更多的高频分量，因此对于传统的24MHz民用接收机而言，能够表现出更好的导航性能。Fig. 4 shows the power spectral densities of the signals of the traditional BOC and the STOC embodiment signal proposed by the present invention, wherein the STOCs (5, 2, 0.9) signal shows higher spectral efficiency. At the same time, STOCs (5, 2, 0.9) are around ±10MHz, and have more high-frequency components than traditional BOCs (5, 2) signals, so for traditional 24MHz civilian receivers, it can show better navigation performance.

图5和图6分别为传统的BOC和本发明所提的STOC实施例信号的Gabor带宽和码跟踪精度，其中环路带宽B_L＝1Hz，接收机带宽为24MHz。由图5可知，当接收机带宽小于10MHz时，STOCs(5,2,0.9)信号的Gabor带宽与BOCs(5,2)信号是相当的，当接收机带宽大于10MHz时，STOCs(5,2,0.9)信号的Gabor带宽明显高于BOCs(5,2)信号，表现出更好的跟踪精度。而且从图6可以发现，对于24MHz常用的民用接收机而言，STOCs(5,2,0.9)信号较BOCs(5,2)信号具有较低的码跟踪误差，具有较高的码跟踪精度。Fig. 5 and Fig. 6 respectively show the Gabor bandwidth and code tracking accuracy of the traditional BOC and the STOC embodiment signal proposed by the present invention, wherein the loop bandwidth _{BL =} 1Hz, and the receiver bandwidth is 24MHz. It can be seen from Figure 5 that when the receiver bandwidth is less than 10MHz, the Gabor bandwidth of the STOCs(5,2,0.9) signal is equivalent to that of the BOCs(5,2) signal, and when the receiver bandwidth is greater than 10MHz, the STOCs(5,2 ,0.9) signal has significantly higher Gabor bandwidth than BOCs(5,2) signal, showing better tracking accuracy. Moreover, it can be found from Fig. 6 that for 24MHz common civilian receivers, the STOCs(5,2,0.9) signal has lower code tracking error and higher code tracking accuracy than the BOCs(5,2) signal.

图7和图8分别为传统的BOC和本发明所提的STOC实施例信号的多径误差包络和平均多径误差曲线。仿真中，选取相关间隔为0.1chip，接收机带宽为24MHz，多径信号与直达信号的幅度比MDR为-6dB。从图7可以看出，本发明所提的STOCs(5,2,0.9)信号相对于BOCs(5,2)信号具有较小的多径误差幅度，而且随着多径信号相对直达信号的额外时延的增加，STOCs(5,2,0.9)信号的多径误差曲线具有较快的衰减速度，能够更快的进行收敛，同时图8表明STOCs(5,2,0.9)信号的最大平均多径误差幅度低于BOCs(5,2)信号，因此，本发明所提的STOCs(5,2,0.9)信号实施例较其它传统信号具有很强的抗多径能力。Fig. 7 and Fig. 8 respectively show the multipath error envelope and the average multipath error curve of the traditional BOC and the STOC embodiment signal proposed by the present invention. In the simulation, the correlation interval is selected as 0.1chip, the receiver bandwidth is 24MHz, and the amplitude ratio MDR of the multipath signal and the direct signal is -6dB. As can be seen from Fig. 7, the STOCs (5, 2, 0.9) signal proposed by the present invention has a smaller multipath error magnitude relative to the BOCs (5, 2) signal, and with the additional With the increase of time delay, the multipath error curve of STOCs(5,2,0.9) signal has a faster decay speed and can converge faster. At the same time, Figure 8 shows that the maximum average multipath The magnitude of the STOCs(5,2,0.9) signal error is lower than that of the BOCs(5,2) signal. Therefore, the embodiment of the STOCs(5,2,0.9) signal proposed by the present invention has a stronger anti-multipath ability than other traditional signals.

综上所述，本发明不受上述实施例的限制，上述实施例和说明书中描述的只是说明本发明的原理，本发明所提的一种基于正弦脉冲三级符号偏移载波调制方法，它可以灵活调整正弦脉冲码片时间的占空比，为导航信号的设计提供了更多的选择，使导航信号具有更好的码跟踪性能、抗干扰、抗多径以及与其它系统信号的兼容能力，并有效抑制功率谱大幅度的旁瓣并提高导航信号的频率效能，为我国未来Compass卫星导航系统的信号波形设计提供了一个新的选择。To sum up, the present invention is not limited by the above-mentioned embodiments, and the above-mentioned embodiments and descriptions only illustrate the principle of the present invention. The present invention proposes a three-level symbol-offset carrier modulation method based on sinusoidal pulses, which The duty cycle of the sine pulse chip time can be flexibly adjusted, providing more choices for the design of the navigation signal, so that the navigation signal has better code tracking performance, anti-interference, anti-multipath and compatibility with other system signals , and effectively suppress the large side lobe of the power spectrum and improve the frequency efficiency of the navigation signal, which provides a new choice for the signal waveform design of the Compass satellite navigation system in my country in the future.

Claims

1. A three-level symbol offset carrier modulation method based on sinusoidal pulses, characterized in that it may further comprise the steps:

(1) First determine the spreading code period T _c , subcarrier period T _sc , sine pulse time width duty ratio ρ, sine or cosine phase subcarrier modulation mode, and construct a three-level symbol sine or cosine phase based on sine pulse The bit carrier signal is specifically expressed as:

Based on the sinusoidal pulse three-level symbol sinusoidal phase subcarrier signal X _S-sub (t, ρ) is:

{X x}_{S S - - s the s u u b b} ((t t,, ρ ρ)) = = s the s i i g g n no ((s the s i i n no ((22 {πf πf}_{s the s c c} t t)))) \times \times {Σ Σ}_{i i = = 00}^{+ + ∞ ∞} {P P}_{\frac{{T T}_{s the s c c}}{22}} ((t t - - i i \frac{{T T}_{s the s c c}}{22},, ρ ρ)),, t t > > 00;;

Based on the sinusoidal pulse three-level symbol cosine phase subcarrier signal X _C-sub (t, ρ) is:

{X x}_{C C - - s the s u u b b} ((t t,, ρ ρ)) = = s the s i i g g n no ((c c o o s the s ((22 {πf πf}_{s the s c c} t t)))) \times \times {Σ Σ}_{i i = = 00}^{+ + ∞ ∞} {P P}_{\frac{{T T}_{s the s c c}}{44}} ((t t - - i i \frac{{T T}_{s the s c c}}{44},, ρ ρ)),, t t > > 00;;

where P _τ (t,ρ) is a sinusoidal pulse waveform with a time width of ρτ, namely sign(t) is a sign function, namely

the s i g no (t) = {\begin{matrix} 1, & t > 0 \\ - 1, & t < 0 \end{matrix};

(2) According to the determined spread spectrum code cycle T _c , the subcarrier cycle T _sc , utilize the pseudo-random sequence to spread the navigation signal, and then combine the obtained spread spectrum signal with the determined sine or cosine phase of step (1) The carrier signal is multiplied in the time domain to obtain a baseband modulation signal based on the sinusoidal pulse three-level symbol sine or cosine phase offset carrier, specifically expressed as:

Based on the sinusoidal pulse three-level symbol sinusoidal phase offset carrier baseband modulation signal S _{STOCs(n,m,ρ)} (t) is:

{S S}_{S S T T O o C C s the s ((n no,, m m,, ρ ρ))} ((t t)) = = d d ((t t)) {Σ Σ}_{l l = = 00}^{L L - - 11} {a a}_{l l} r r e e c c t t ((t t - - {lT lT}_{c c})) \times \times {X x}_{S S - - s the s u u b b} ((t t,, ρ ρ)),, t t > > 00;;

Based on the sinusoidal pulse three-level symbol cosine phase offset carrier baseband modulation signal S _{STOCc(n,m,ρ)} (t) is:

{S S}_{S S T T O o C C c c ((n no,, m m,, ρ ρ))} ((t t)) = = d d ((t t)) {Σ Σ}_{l l = = 00}^{L L - - 11} {a a}_{l l} r r e e c c t t ((t t - - {lT lT}_{c c})) \times \times {X x}_{C C - - s the s u u b b} ((t t,, ρ ρ)),, t t > > 00;;

Among them, d(t) is the navigation signal data channel information; a _l is the lth spreading code of the pseudo-random spreading sequence; L is the chip length of the pseudo-random sequence; rect(t) is the rectangular gate function, namely or

no = \frac{1}{T_{the s c} \times 1.023 m h z}; m = \frac{f_{c}}{1.023 m h z}

or

m = \frac{1}{T_{c} \times 1.023 m h z};

(3) Carry out the carrier modulation of the quadrature branch based on the sine pulse three-level symbol sine or cosine phase offset carrier baseband modulation signal described in step (2), obtain based on the sinusoidal pulse three-level symbol sine or cosine phase offset Carrier shift modulation signal, specifically expressed as:

Based on the sinusoidal pulse three-level symbol sinusoidal phase offset carrier modulation signal M _{STOCs(n,m,ρ)} (t,ρ) is:

\begin{matrix} {M m}_{S S T T O o C C s the s ((n no,, m m,, ρ ρ))} ((t t,, ρ ρ)) = = [[d d ((t t)) {Σ Σ}_{l l = = 00}^{L L - - 11} {a a}_{l l} r r e e c c t t ((t t - - {lT lT}_{c c})) \times \times s the s i i g g n no ((sin sin ((22 {πf πf}_{s the s c c} t t)))) \times \times {Σ Σ}_{i i = = 00}^{+ + ∞ ∞} {P P}_{\frac{{T T}_{s the s c c}}{22}} ((t t - - i i \frac{{T T}_{s the s c c}}{22},, ρ ρ))]] cos cos ((22 {πf πf}_{c c a a r r} t t)) \\ + + [[p p ((t t)) {Σ Σ}_{k k = = 00}^{L L - - 11} {b b}_{k k} r r e e c c t t ((t t - - {kT kT}_{c c})) \times \times s the s i i g g n no ((sin sin ((22 {πf πf}_{s the s c c} t t)))) \times \times {Σ Σ}_{i i = = 00}^{+ + ∞ ∞} {P P}_{\frac{{T T}_{s the s c c}}{22}} ((t t - - i i \frac{{T T}_{s the s c c}}{22},, ρ ρ))]] sin sin ((22 {πf πf}_{c c a a r r} t t)) \end{matrix};;

The carrier modulation signal M _{STOCc(n,m,ρ)} (t,ρ) based on the three-level symbol cosine phase offset of the sine pulse is:

\begin{matrix} {M m}_{S S T T O o C C c c ((n no,, m m,, ρ ρ))} ((t t,, ρ ρ)) = = [[d d ((t t)) {Σ Σ}_{l l = = 00}^{L L - - 11} {a a}_{l l} r r e e c c t t ((t t - - {lT lT}_{c c})) \times \times s the s i i g g n no ((cos cos ((22 {πf πf}_{s the s c c} t t)))) \times \times {Σ Σ}_{i i = = 00}^{+ + ∞ ∞} {P P}_{\frac{{T T}_{s the s c c}}{44}} ((t t - - i i \frac{{T T}_{s the s c c}}{44},, ρ ρ))]] cos cos ((22 {πf πf}_{c c a a r r} t t)) \\ + + [[p p ((t t)) {Σ Σ}_{k k = = 00}^{L L - - 11} {b b}_{k k} r r e e c c t t ((t t - - {kT kT}_{c c})) \times \times s the s i i g g n no ((cos cos ((22 {πf πf}_{s the s c c} t t)))) \times \times {Σ Σ}_{i i = = 00}^{+ + ∞ ∞} {P P}_{\frac{{T T}_{s the s c c}}{44}} ((t t - - i i \frac{{T T}_{s the s c c}}{44},, ρ ρ))]] sin sin ((22 {πf πf}_{c c a a r r} t t)) \end{matrix};;

Among them, d(t) is the navigation signal data channel information; p(t) is the pilot channel information, and the value is all +1 or -1; a _l is the lth spreading code of the pseudo-random spreading sequence of the in-phase branch ; b _k is the kth spreading code of the pseudo-random spreading sequence of the orthogonal branch; f _car is the carrier frequency.

(4) The performance evaluation of the navigation signal based on the sinusoidal pulse three-level symbol offset carrier modulation signal obtained in step (3), if the code tracking accuracy, anti-multipath and compatibility of the signal do not meet the designed navigation system performance Requirements and constraints, return to step (1), re-determine the spreading code period T _c , subcarrier period T _sc , sine or cosine phase subcarrier modulation mode, and sine pulse time width duty ratio ρ.

2. based on sinusoidal pulse three-level symbol offset carrier modulation method according to claim 1, it is characterized in that, the value of described spreading code frequency f _c and sub-carrier frequency f _sc is an integer multiple of 1.023MHz.

3. based on sinusoidal pulse three-level symbol offset carrier modulation method according to claim 1, it is characterized in that, described based on sinusoidal pulse three-level symbol sinusoidal phase offset carrier baseband modulation signal power spectral density G _{STOCs (n, m,ρ)} (f) is:

The described power spectral density G _{STOCc (n, m, ρ)} (f) based on the sinusoidal pulse three-level symbol cosine phase offset carrier baseband modulation signal is:

where h is the modulation index, namely or