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

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 kind of based on sine pulse three grades of symbol offset carrier modulating methods

Technical field

The present invention relates to a kind of implementation method of satellite navigation system signals, be specifically related to a kind of based on sine pulse three grades of symbol offset carrier modulating methods.

Background technology

Navigation modulation signal waveform is the key link in Navigation Signal System design, and signal waveform by affecting autocorrelation function and the power spectrum of navigation signal, and then affects the performance of navigational system.GLONASS (Global Navigation Satellite System) (GlobalNavigationSatelliteSystem can be shared better to make multi-signal, GNSS) limited frequency, improve distance accuracy and the interference free performance of signal further, new signal madulation mode constantly presents simultaneously.Binary offset carrier (BinaryOffsetCarrier, BOC (n, m)) be a kind of new type of modulation mode that can meet above-mentioned requirements, wherein spreading code frequency is m × 1.023MHz, sub-carrier frequencies is n × 1.023MHz, its implementation refers to document Betz.J, " TheOffsetCarrierModulationforGPSModernization, " IONNTM, SanDiego, CA, January25-27,1999.

Betz.J document " BinaryOffsetCarrierModulationsforRadionavigation; " Navigation:JournaloftheInstituteofNavigation, vol.48, No.4, Winter2001-2002. point out in, the same band, take same band and signal projector and receiver are done to same simple designs condition under, the Performance Ratio BPSK modulation signal of BOC modulation signal is more superior.BOC modulation has been widely used in the GPS (Global Position System) such as GPS, Galileo and Compass at present.

Along with the continuous increase of satellite navigation signals quantity, frequency spectrum resource is nervous, and the interference improved under finite bandwidth between signal performance and reduction adjacent signals becomes current research emphasis.The BOC modulator approach provided in article can bring outer significantly secondary lobe that power amplification efficiency is reduced, and the code tracking performance of signal, anti-multipath and antijamming capability are still not ideal enough, therefore the present invention proposes a kind of based on sine pulse three grades of symbol offset carrier modulating method (SinusoidalThree-levelsOffsetCarrier, STOC (n, m, ρ)), wherein sub-carrier signal can value be ± 1 and 0, and ± 1 signal waveform is represented by sine pulse, the method can adjust sub-carrier signal waveform chip delay dutycycle flexibly, for the design of navigation signal provides more choices, and by selected suitable parameter, can the main lobe of flexible power spectrum signal and the splitting degree of secondary lobe, navigation signal is made to have good code tracking performance, anti-interference and ability of anti-multipath, with other system signal compatibility, important meaning is had for the Navigation and localization performance promoting satellite navigation system, simultaneously also for the signal waveform design of the following Compass satellite navigation system of China provides a new selection.

Summary of the invention

The object of the invention is to propose a kind of can the main lobe of flexible power spectrum signal and the splitting degree of secondary lobe, make navigation signal have good code tracking performance, anti-interference and ability of anti-multipath, with other system signal compatibility based on sine pulse three grades of symbol offset carrier modulating methods.

The object of the present invention is achieved like this:

(1) spreading code cycle T is first determined _c, subcarrier cycle T _sc, sine pulse time width dutycycle ρ, sinusoidal or cosine phase subcarrier modulation modes, constructs a kind of based on sine pulse three grades of symbols sines or cosine phase sub-carrier signal, is specifically expressed as:

Based on sine pulse three grades of symbol sinusoidal phase sub-carrier signal X _s-sub(t, ρ) is:

$X_{S-sub}(t,\mathrm{\ρ})=sign\left(sin\right(2{\mathrm{\πf}}_{sc}t\left)\right)\×\underset{i=0}{\overset{+\mathrm{\∞}}{\Σ}}{P}_{\frac{T_{sc}}{2}}(t-i\frac{T_{sc}}{2},\mathrm{\ρ}),t>0;$

Based on sine pulse three grades of symbol cosine phase sub-carrier signal X _c-sub(t, ρ) is:

$X_{C-sub}(t,\mathrm{\ρ})=sign\left(cos\right(2{\mathrm{\πf}}_{sc}t\left)\right)\×\underset{i=0}{\overset{+\mathrm{\∞}}{\Σ}}{P}_{\frac{T_{sc}}{4}}(t-i\frac{T_{sc}}{4},\mathrm{\ρ}),t>0;$

Wherein P _τthe sine pulse waveform of (t, ρ) to be time width be ρ τ, namely sign (t) is sign function, namely $sign\left(t\right)=\{\begin{array}{cc}1,& t>0\\ -1,& t<0\end{array};$

(2) according to the spreading code cycle T determined _c, subcarrier cycle T _scpseudo-random sequence is utilized to carry out spread spectrum to navigation signal, then the spread-spectrum signal obtained and step (1) determined sine or cosine phase sub-carrier signal are carried out time domain multiplication, obtain a kind of based on sine pulse three grades of symbols sines or cosine phase offset carrier baseband modulation signal, be specifically expressed as:

Based on sine pulse three grades of symbol sinusoidal phase offset carrier baseband modulation signal S _{sTOCs (n, m, ρ)}(t) be:

$S_{STOCs(n,m,\mathrm{\&rho;})}\left(t\right)=d\left(t\right)\underset{l=0}{\overset{L-1}{\&Sigma;}}{a}_{l}rect(t-{\mathrm{lT}}_c)\&times;X_{S-sub}(t,\mathrm{\&rho;}),t>0;$

Based on sine pulse three grades of symbol cosine phase offset carrier baseband modulation signal S _{sTOCc (n, m, ρ)}(t) be:

$S_{STOCc(n,m,\mathrm{\&rho;})}\left(t\right)=d\left(t\right)\underset{l=0}{\overset{L-1}{\&Sigma;}}{a}_{l}rect(t-{\mathrm{lT}}_c)\&times;X_{C-sub}(t,\mathrm{\&rho;}),t>0;$

Wherein d (t) is navigation signal data channel information; a _ll spreading code of pseudorandom spreading sequence; L is the chip lengths of pseudo-random sequence; Rect (t) is rectangular door function, namely or $n=\frac{1}{T_{sc}\&times;1.023MHz};m=\frac{f_c}{1.023MHz}$ Or $m=\frac{1}{T_c\&times;1.023MHz};$

(3) by a kind of carrier modulation of carrying out quadrature branch based on sine pulse three grades of symbols sines or cosine phase offset carrier baseband modulation signal described in step (2), obtain or cosine phase offset carrier (boc) modulated signals sinusoidal based on sine pulse three grades of symbols, be specifically expressed as:

Based on sine pulse three grades of symbol sinusoidal phase offset carrier (boc) modulated signals M _{sTOCs (n, m, ρ)}(t, ρ) is:

$\begin{array}{c}{M}_{STOCs(n,m,\mathrm{\&rho;})}(t,\mathrm{\&rho;})=\&lsqb;d\left(t\right)\underset{l=0}{\overset{L-1}{\&Sigma;}}{a}_{l}rect(t-{\mathrm{lT}}_c)\&times;sign\left(\sin \right(2{\mathrm{\&pi;f}}_{sc}t\left)\right)\&times;\underset{i=0}{\overset{+\mathrm{\&infin;}}{\&Sigma;}}{P}_{\frac{T_{sc}}{2}}\left(t-i\frac{T_{sc}}{2},\mathrm{\&rho;}\right)\&rsqb;\cos \left(2{\mathrm{\&pi;f}}_{car}t\right)\\ +\&lsqb;p\left(t\right)\underset{k=0}{\overset{L-1}{\&Sigma;}}{b}_{k}rect(t-{\mathrm{kT}}_c)\&times;sign\left(\sin \right(2{\mathrm{\&pi;f}}_{sc}t\left)\right)\&times;\underset{i=0}{\overset{+\mathrm{\&infin;}}{\&Sigma;}}{P}_{\frac{T_{sc}}{2}}\left(t-i\frac{T_{sc}}{2},\mathrm{\&rho;}\right)\&rsqb;\sin \left(2{\mathrm{\&pi;f}}_{car}t\right)\end{array};$

Based on sine pulse three grades of symbol cosine phase offset carrier (boc) modulated signals M _{sTOCc (n, m, ρ)}(t, ρ) is:

$\begin{array}{c}{M}_{STOCc(n,m,\mathrm{\&rho;})}(t,\mathrm{\&rho;})=\&lsqb;d\left(t\right)\underset{l=0}{\overset{L-1}{\&Sigma;}}{a}_{l}rect(t-{\mathrm{lT}}_c)\&times;sign\left(\cos \right(2{\mathrm{\&pi;f}}_{sc}t\left)\right)\&times;\underset{i=0}{\overset{+\mathrm{\&infin;}}{\&Sigma;}}{P}_{\frac{T_{sc}}{4}}\left(t-i\frac{T_{sc}}{4},\mathrm{\&rho;}\right)\&rsqb;\cos \left(2{\mathrm{\&pi;f}}_{car}t\right)\\ +\&lsqb;p\left(t\right)\underset{k=0}{\overset{L-1}{\&Sigma;}}{b}_{k}rect(t-{\mathrm{kT}}_c)\&times;sign\left(\cos \right(2{\mathrm{\&pi;f}}_{sc}t\left)\right)\&times;\underset{i=0}{\overset{+\mathrm{\&infin;}}{\&Sigma;}}{P}_{\frac{T_{sc}}{4}}\left(t-i\frac{T_{sc}}{4},\mathrm{\&rho;}\right)\&rsqb;\sin \left(2{\mathrm{\&pi;f}}_{car}t\right)\end{array};$

Wherein d (t) is navigation signal data channel information; P (t) is pilot channel information, and value is complete+1 or-1; a _ll spreading code of in-phase branch pseudorandom spreading sequence; b _kit is a kth spreading code of quadrature branch pseudorandom spreading sequence; f _carit is carrier frequency.

(4) Performance Evaluation carrying out navigation signal based on sine pulse three grades of symbol offset carrier (boc) modulated signals will obtained in step (3), if the code tracking precision of signal, anti-multipath and compatibility do not meet designed navigational system performance requirement and constraint condition, then return step (1), redefine spreading code cycle T _c, subcarrier cycle T _sc, sinusoidal or cosine phase subcarrier modulation modes, and sine pulse time width dutycycle ρ.

The present invention can also comprise:

Described spreading code frequency f _cwith sub-carrier frequencies f _scvalue be the integral multiple of 1.023MHz.

Described based on sine pulse three grades of symbol sinusoidal phase offset carrier baseband modulation signal power spectrum density G _{sTOCs (n, m, ρ)}(f) be:

Described based on sine pulse three grades of symbol cosine phase offset carrier baseband modulation signal power spectrum density G _{sTOCc (n, m, ρ)}(f) be:

Wherein h is modulation index, namely $h=\frac{2f_{sc}}{f_c}$ Or $h=\frac{2n}{m}.$

The principal feature of method of the present invention is as follows:

(1) dirigibility of Design of Signal is high: adjustment sine pulse chip delay dutycycle flexibly, for the design of navigation signal provides more choices, and by selected suitable parameter, can the main lobe of flexible power spectrum signal and the splitting degree of secondary lobe.

(2) tracking accuracy is high: in receiver bandwidth, and the power spectrum of modulation signal of the present invention has splitting ability and amplitude is comparatively large, under the condition of Bandwidth-Constrained, has higher Gabor bandwidth and lower code tracking error.

(3) ability of anti-multipath is strong: modulation signal of the present invention has permanent envelope trait, is particularly suitable for adopting the power of efficient non-linear amplifiers and all limited the urban satellite navigation service of bandwidth, its multipath error envelope decay faster and amplitude is lower.

(4) compatible high: the power spectrum side lobe attenuation speed of modulation signal of the present invention is faster and amplitude is lower, less to other navigation signal interference of same frequency range.

Accompanying drawing explanation

Fig. 1 is STOC signal madulation model and implementation method process flow diagram;

Fig. 2 is STOC channel distortion experienced signal waveform;

Fig. 3 is the power spectrum density of STOC embodiment signal under different sine pulse duty ratio of time ρ;

The power spectrum density of the STOC embodiment signal that Fig. 4 carries for traditional BOC and the present invention;

The Gabor bandwidth of the STOC embodiment signal that Fig. 5 carries for traditional BOC and the present invention;

The code tracking precision of the STOC embodiment signal that Fig. 6 carries for traditional BOC and the present invention;

The multipath error envelope of the STOC embodiment signal that Fig. 7 carries for traditional BOC and the present invention;

The average multipath error of the STOC embodiment signal that Fig. 8 carries for traditional BOC and the present invention.

Embodiment

Below in conjunction with drawings and Examples, the invention will be further described:

The STOC signal madulation model that Fig. 1 and Fig. 2 carries for the present invention, implementation method process flow diagram and sub-carrier signal waveform, each symbol wherein in Fig. 1 is defined as follows:

D (t): navigation signal data channel information;

P (t): pilot channel information;

A _l: the pseudorandom spread spectrum code sequence of in-phase branch;

B _l: the pseudorandom spread spectrum code sequence of quadrature branch;

Rec (t): rectangular door function;

X _s-sub(t, ρ): described one is based on sine pulse three grades of symbol sinusoidal phase sub-carrier signal waveforms;

X _c-sub(t, ρ): described one is based on sine pulse three grades of symbol cosine phase sub-carrier signal waveforms;

M _sTOC(t, ρ): described one is based on sine pulse three grades of symbol offset carrier (boc) modulated signals;

F _c: spreading code frequency;

F _car: carrier frequency;

F _sc: sub-carrier frequencies;

Composition graphs 1, implementation method of the present invention is as follows:

(1) spreading code frequency f is first determined _cor spreading code cycle T _c(frequency and cycle each other inverse can determine arbitrarily one of them parameter), sub-carrier frequencies f _scor subcarrier cycle T _sc, sine pulse time width dutycycle ρ and sinusoidal or cosine phase subcarrier modulation modes, construct a kind of based on sine pulse three grades of symbols sines or cosine phase sub-carrier signal, be specifically expressed as:

Based on sine pulse three grades of symbol sinusoidal phase sub-carrier signal X _s-sub(t, ρ) is:

$X_{S-sub}(t,\mathrm{\&rho;})=sign\left(\sin \right(2{\mathrm{\&pi;f}}_{sc}t\left)\right)\&times;\underset{i=0}{\overset{+\mathrm{\&infin;}}{\&Sigma;}}{P}_{\frac{T_{sc}}{2}}(t-i\frac{T_{sc}}{2},\mathrm{\&rho;}),t>0;$

Based on sine pulse three grades of symbol cosine phase sub-carrier signal X _c-sub(t, ρ) is:

$X_{C-sub}(t,\mathrm{\&rho;})=sign\left(cos\right(2{\mathrm{\&pi;f}}_{sc}t\left)\right)\&times;\underset{i=0}{\overset{+\mathrm{\&infin;}}{\&Sigma;}}{P}_{\frac{T_{sc}}{4}}(t-i\frac{T_{sc}}{4},\mathrm{\&rho;}),t>0;$

Wherein P _τthe sine pulse waveform of (t, ρ) to be time width be ρ τ, namely sign (t) is sign function, namely $sign\left(t\right)=\{\begin{array}{cc}1,& t>0\\ -1,& t<0\end{array};$

(2) according to the spreading code frequency f determined _cor spreading code cycle T _cwith sub-carrier frequencies f _scor subcarrier cycle T _scpseudo-random sequence is utilized to carry out spread spectrum to navigation signal, then the spread-spectrum signal obtained and step (1) determined sine or cosine phase sub-carrier signal are carried out time domain multiplication, obtain a kind of based on sine pulse three grades of symbols sines or cosine phase offset carrier baseband modulation signal, be specifically expressed as:

Based on sine pulse three grades of symbol sinusoidal phase offset carrier baseband modulation signal S _{sTOCs (n, m, ρ)}(t) be:

$S_{STOCs(n,m,\mathrm{\&rho;})}\left(t\right)=d\left(t\right)\underset{l=0}{\overset{L-1}{\&Sigma;}}{a}_{l}rect(t-{\mathrm{lT}}_c)\&times;X_{S-sub}(t,\mathrm{\&rho;}),t>0;$

Based on sine pulse three grades of symbol cosine phase offset carrier baseband modulation signal S _{sTOCc (n, m, ρ)}(t) be:

$S_{STOCc(n,m,\mathrm{\&rho;})}\left(t\right)=d\left(t\right)\underset{l=0}{\overset{L-1}{\&Sigma;}}{a}_{l}rect(t-{\mathrm{lT}}_c)\&times;X_{C-sub}(t,\mathrm{\&rho;}),t>0;$

Wherein d (t) is navigation signal data channel information; a _ll spreading code of pseudorandom spreading sequence; L is the chip lengths of pseudo-random sequence; Rect (t) is rectangular door function, namely or $n=\frac{1}{T_{sc}\&times;1.023MHz};m=\frac{f_c}{1.023MHz}$ Or $m=\frac{1}{T_c\&times;1.023MHz};$

(3) by a kind of carrier modulation of carrying out quadrature branch based on sine pulse three grades of symbols sines or cosine phase offset carrier baseband modulation signal described in step (2), obtain or cosine phase offset carrier (boc) modulated signals sinusoidal based on sine pulse three grades of symbols, be specifically expressed as:

Based on sine pulse three grades of symbol sinusoidal phase offset carrier (boc) modulated signals M _{sTOCs (n, m, ρ)}(t, ρ) is:

$\begin{array}{c}{M}_{STOCs(n,m,\mathrm{\&rho;})}(t,\mathrm{\&rho;})=\&lsqb;d\left(t\right)\underset{l=0}{\overset{L-1}{\&Sigma;}}{a}_{l}rect(t-{\mathrm{lT}}_c)\&times;sign\left(\sin \right(2{\mathrm{\&pi;f}}_{sc}t\left)\right)\&times;\underset{i=0}{\overset{+\mathrm{\&infin;}}{\&Sigma;}}{P}_{\frac{T_{sc}}{2}}\left(t-i\frac{T_{sc}}{2},\mathrm{\&rho;}\right)\&rsqb;\cos \left(2{\mathrm{\&pi;f}}_{car}t\right)\\ +\&lsqb;p\left(t\right)\underset{k=0}{\overset{L-1}{\&Sigma;}}{b}_{k}rect(t-{\mathrm{kT}}_c)\&times;sign\left(\sin \right(2{\mathrm{\&pi;f}}_{sc}t\left)\right)\&times;\underset{i=0}{\overset{+\mathrm{\&infin;}}{\&Sigma;}}{P}_{\frac{T_{sc}}{2}}\left(t-i\frac{T_{sc}}{2},\mathrm{\&rho;}\right)\&rsqb;\sin \left(2{\mathrm{\&pi;f}}_{car}t\right)\end{array};$

Based on sine pulse three grades of symbol cosine phase offset carrier (boc) modulated signals M _{sTOCc (n, m, ρ)}(t, ρ) is:

$\begin{array}{c}{M}_{STOCc(n,m,\mathrm{\&rho;})}(t,\mathrm{\&rho;})=\&lsqb;d\left(t\right)\underset{l=0}{\overset{L-1}{\&Sigma;}}{a}_{l}rect(t-{\mathrm{lT}}_c)\&times;sign\left(\cos \right(2{\mathrm{\&pi;f}}_{sc}t\left)\right)\&times;\underset{i=0}{\overset{+\mathrm{\&infin;}}{\&Sigma;}}{P}_{\frac{T_{sc}}{4}}\left(t-i\frac{T_{sc}}{4},\mathrm{\&rho;}\right)\&rsqb;\cos \left(2{\mathrm{\&pi;f}}_{car}t\right)\\ +\&lsqb;p\left(t\right)\underset{k=0}{\overset{L-1}{\&Sigma;}}{b}_{k}rect(t-{\mathrm{kT}}_c)\&times;sign\left(\sin \right(2{\mathrm{\&pi;f}}_{sc}t\left)\right)\&times;\underset{i=0}{\overset{+\mathrm{\&infin;}}{\&Sigma;}}{P}_{\frac{T_{sc}}{4}}\left(t-i\frac{T_{sc}}{4},\mathrm{\&rho;}\right)\&rsqb;\sin \left(2{\mathrm{\&pi;f}}_{car}t\right)\end{array};$

Wherein d (t) is navigation signal data channel information; P (t) is pilot channel information, and value is complete+1 or-1; a _ll spreading code of in-phase branch pseudorandom spreading sequence; b _kit is a kth spreading code of quadrature branch pseudorandom spreading sequence; f _carit is carrier frequency.

(4) Performance Evaluation carrying out navigation signal based on sine pulse three grades of symbol offset carrier (boc) modulated signals will obtained in step (3), if the code tracking precision of signal, anti-multipath and compatibility do not meet designed navigational system performance requirement and constraint condition, then return step (1), redefine spreading code frequency f _cor spreading code cycle T _c, sub-carrier frequencies f _scor subcarrier cycle T _sc, sinusoidal or cosine phase subcarrier modulation modes, and sine pulse time width dutycycle ρ.

Described spreading code frequency f _cwith sub-carrier frequencies f _scvalue be the integral multiple of 1.023MHz.

Described based on sine pulse three grades of symbol sinusoidal phase offset carrier baseband modulation signal power spectrum density G _{sTOCs (n, m, ρ)}(f) be:

Described based on sine pulse three grades of symbol cosine phase offset carrier baseband modulation signal power spectrum density G _{sTOCc (n, m, ρ)}(f) be:

Wherein h is modulation index, namely $h=\frac{2f_{sc}}{f_c}$ Or $h=\frac{2n}{m}$

The power spectrum density of STOC embodiment signal under different sine pulse time width dutycycle ρ that Fig. 3 carries for the present invention, as shown in Figure 3, by changing sine pulse time width dutycycle ρ, STOC signal can the splitting degree of flexible power spectrum signal main lobe and secondary lobe, and along with the increase of ρ, the while that power spectrum signal main lobe energy being concentrated more, side lobe attenuation speed is faster, this improves the flexibility ratio of navigation signal design undoubtedly, can better with existing signal compatibility, signal waveform design for the following Compass satellite navigation system of China provides a new selection.

The power spectrum density of the STOC embodiment signal that Fig. 4 carries for traditional BOC and the present invention, wherein STOCs (5,2,0.9) signal list reveals higher frequency spectrum usefulness.Simultaneously STOCs (5,2,0.9) is near ± 10MHz, and more traditional BOCs (5,2) signal has more high fdrequency component, therefore for traditional 24MHz commercial receiver, can show better navigation performance.

Fig. 5 and Fig. 6 is respectively the Gabor bandwidth sum code tracking precision of the STOC embodiment signal that traditional BOC and the present invention put forward, its loop bandwidth B _l=1Hz, receiver bandwidth is 24MHz.As shown in Figure 5, when receiver bandwidth is less than 10MHz, STOCs (5,2,0.9) the Gabor bandwidth of signal and BOCs (5,2) signal is suitable, when receiver bandwidth is greater than 10MHz, and STOCs (5,2,0.9) the Gabor bandwidth of signal is apparently higher than BOCs (5,2) signal, shows better tracking accuracy.And can find from Fig. 6, for the commercial receiver that 24MHz is conventional, STOCs (5,2,0.9) signal comparatively BOCs (5,2) signal has lower code tracking error, has higher code tracking precision.

Fig. 7 and Fig. 8 is respectively the multipath error envelope of the STOC embodiment signal that traditional BOC and the present invention carry and average multipath error curve.In emulation, choosing related interval is 0.1chip, and receiver bandwidth is 24MHz, and the Amplitude Ratio MDR of multipath signal and direct signal is-6dB.As can be seen from Figure 7, the STOCs (5 that the present invention carries, 2, 0.9) signal is relative to BOCs (5, 2) signal has less multipath error amplitude, and the increase of extra latency along with the relative direct signal of multipath signal, STOCs (5, 2, 0.9) the multipath error curve of signal has the rate of decay faster, can restrain faster, Fig. 8 shows STOCs (5 simultaneously, 2, 0.9) the maximum average multipath error amplitude of signal is lower than BOCs (5, 2) signal, therefore, the STOCs (5 that the present invention carries, 2, 0.9) signal embodiment has very strong ability of anti-multipath compared with other classical signal.

In sum, the present invention is not restricted to the described embodiments, what describe in above-described embodiment and instructions just illustrates principle of the present invention, the one that the present invention carries is based on sine pulse three grades of symbol offset carrier modulating methods, it can adjust the dutycycle of sine pulse chip delay flexibly, for the design of navigation signal provides more choices, navigation signal is made to have better code tracking performance, anti-interference, anti-multipath and the compatibility with other system signal, and effectively suppress power spectrum significantly secondary lobe improve the frequency usefulness of navigation signal, signal waveform design for the following Compass satellite navigation system of China provides a new selection.

Claims (3)

1., based on sine pulse three grades of symbol offset carrier modulating methods, it is characterized in that comprising the following steps:

(1) spreading code cycle T is first determined _c, subcarrier cycle T _sc, sine pulse time width dutycycle ρ, sinusoidal or cosine phase subcarrier modulation modes, constructs a kind of based on sine pulse three grades of symbols sines or cosine phase sub-carrier signal, is specifically expressed as:

Based on sine pulse three grades of symbol sinusoidal phase sub-carrier signal X _s-sub(t, ρ) is:

$X_{S-sub}(t,\mathrm{\&rho;})=sign\left(sin\right(2{\mathrm{\&pi;f}}_{sc}t\left)\right)\&times;\underset{i=0}{\overset{+\mathrm{\&infin;}}{\&Sigma;}}{P}_{\frac{T_{sc}}{2}}(t-i\frac{T_{sc}}{2},\mathrm{\&rho;}),t>0;$

Based on sine pulse three grades of symbol cosine phase sub-carrier signal X _c-sub(t, ρ) is:

$X_{C-sub}(t,\mathrm{\&rho;})=sign\left(cos\right(2{\mathrm{\&pi;f}}_{sc}t\left)\right)\&times;\underset{i=0}{\overset{+\mathrm{\&infin;}}{\&Sigma;}}{P}_{\frac{T_{sc}}{4}}(t-i\frac{T_{sc}}{4},\mathrm{\&rho;}),t>0;$

Wherein P _τthe sine pulse waveform of (t, ρ) to be time width be ρ τ, namely sign (t) is sign function, namely $sign\left(t\right)=\{\begin{array}{cc}1,& t>0\\ -1,& t<0\end{array};$

(2) according to the spreading code cycle T determined _c, subcarrier cycle T _scpseudo-random sequence is utilized to carry out spread spectrum to navigation signal, then the spread-spectrum signal obtained and step (1) determined sine or cosine phase sub-carrier signal are carried out time domain multiplication, obtain a kind of based on sine pulse three grades of symbols sines or cosine phase offset carrier baseband modulation signal, be specifically expressed as:

Based on sine pulse three grades of symbol sinusoidal phase offset carrier baseband modulation signal S _{sTOCs (n, m, ρ)}(t) be:

$S_{STOCs(n,m,\mathrm{\&rho;})}\left(t\right)=d\left(t\right)\underset{l=0}{\overset{L-1}{\&Sigma;}}{a}_{l}rect(t-{\mathrm{lT}}_c)\&times;X_{S-sub}(t,\mathrm{\&rho;}),t>0;$

Based on sine pulse three grades of symbol cosine phase offset carrier baseband modulation signal S _{sTOCc (n, m, ρ)}(t) be:

$S_{STOCc(n,m,\mathrm{\&rho;})}\left(t\right)=d\left(t\right)\underset{l=0}{\overset{L-1}{\&Sigma;}}{a}_{l}rect(t-{\mathrm{lT}}_c)\&times;X_{C-sub}(t,\mathrm{\&rho;}),t>0;$

Wherein d (t) is navigation signal data channel information; a _ll spreading code of pseudorandom spreading sequence; L is the chip lengths of pseudo-random sequence; Rect (t) is rectangular door function, namely or $n=\frac{1}{T_{sc}\&times;1.023MHz};m=\frac{f_c}{1.023MHz}$ Or $m=\frac{1}{T_c\&times;1.023MHz};$

(3) by a kind of carrier modulation of carrying out quadrature branch based on sine pulse three grades of symbols sines or cosine phase offset carrier baseband modulation signal described in step (2), obtain or cosine phase offset carrier (boc) modulated signals sinusoidal based on sine pulse three grades of symbols, be specifically expressed as:

Based on sine pulse three grades of symbol sinusoidal phase offset carrier (boc) modulated signals M _{sTOCs (n, m, ρ)}(t, ρ) is:

$\begin{array}{c}{M}_{STOCs(n,m,\mathrm{\&rho;})}(t,\mathrm{\&rho;})=\&lsqb;d\left(t\right)\underset{l=0}{\overset{L-1}{\&Sigma;}}{a}_{l}rect(t-{\mathrm{lT}}_c)\&times;sign\left(\sin \right(2{\mathrm{\&pi;f}}_{sc}t\left)\right)\&times;\underset{i=0}{\overset{+\mathrm{\&infin;}}{\&Sigma;}}{P}_{\frac{T_{sc}}{2}}\left(t-i\frac{T_{sc}}{2},\mathrm{\&rho;}\right)\&rsqb;\cos \left(2{\mathrm{\&pi;f}}_{car}t\right)\\ +\&lsqb;p\left(t\right)\underset{k=0}{\overset{L-1}{\&Sigma;}}{b}_{k}rect(t-{\mathrm{kT}}_c)\&times;sign\left(\sin \right(2{\mathrm{\&pi;f}}_{sc}t\left)\right)\&times;\underset{i=0}{\overset{+\mathrm{\&infin;}}{\&Sigma;}}{P}_{\frac{T_{sc}}{2}}\left(t-i\frac{T_{sc}}{2},\mathrm{\&rho;}\right)\&rsqb;\sin \left(2{\mathrm{\&pi;f}}_{car}t\right)\end{array};$

Based on sine pulse three grades of symbol cosine phase offset carrier (boc) modulated signals M _{sTOCc (n, m, ρ)}(t, ρ) is:

$\begin{array}{c}{M}_{STOCc(n,m,\mathrm{\&rho;})}(t,\mathrm{\&rho;})=\&lsqb;d\left(t\right)\underset{l=0}{\overset{L-1}{\&Sigma;}}{a}_{l}rect(t-{\mathrm{lT}}_c)\&times;sign\left(\cos \right(2{\mathrm{\&pi;f}}_{sc}t\left)\right)\&times;\underset{i=0}{\overset{+\mathrm{\&infin;}}{\&Sigma;}}{P}_{\frac{T_{sc}}{4}}\left(t-i\frac{T_{sc}}{4},\mathrm{\&rho;}\right)\&rsqb;\cos \left(2{\mathrm{\&pi;f}}_{car}t\right)\\ +\&lsqb;p\left(t\right)\underset{k=0}{\overset{L-1}{\&Sigma;}}{b}_{k}rect(t-{\mathrm{kT}}_c)\&times;sign\left(\cos \right(2{\mathrm{\&pi;f}}_{sc}t\left)\right)\&times;\underset{i=0}{\overset{+\mathrm{\&infin;}}{\&Sigma;}}{P}_{\frac{T_{sc}}{4}}\left(t-i\frac{T_{sc}}{4},\mathrm{\&rho;}\right)\&rsqb;\sin \left(2{\mathrm{\&pi;f}}_{car}t\right)\end{array};$

Wherein d (t) is navigation signal data channel information; P (t) is pilot channel information, and value is complete+1 or-1; a _ll spreading code of in-phase branch pseudorandom spreading sequence; b _kit is a kth spreading code of quadrature branch pseudorandom spreading sequence; f _carit is carrier frequency.

(4) Performance Evaluation carrying out navigation signal based on sine pulse three grades of symbol offset carrier (boc) modulated signals will obtained in step (3), if the code tracking precision of signal, anti-multipath and compatibility do not meet designed navigational system performance requirement and constraint condition, then return step (1), redefine spreading code cycle T _c, subcarrier cycle T _sc, sinusoidal or cosine phase subcarrier modulation modes, and sine pulse time width dutycycle ρ.

2. according to claim 1ly to it is characterized in that based on sine pulse three grades of symbol offset carrier modulating methods, described spreading code frequency f _cwith sub-carrier frequencies f _scvalue be the integral multiple of 1.023MHz.

3. according to claim 1ly to it is characterized in that based on sine pulse three grades of symbol offset carrier modulating methods, described based on sine pulse three grades of symbol sinusoidal phase offset carrier baseband modulation signal power spectrum density G _{sTOCs (n, m, ρ)}(f) be:

Described based on sine pulse three grades of symbol cosine phase offset carrier baseband modulation signal power spectrum density G _{sTOCc (n, m, ρ)}(f) be:

Wherein h is modulation index, namely or