CN101854326B - Signal modulation method and signal demodulation method - Google Patents

Abstract

The invention provides a signal modulation method and a signal demodulation method. The signal modulation method includes the following steps: for a Xth channel, respectively multiplying the Xth channel baseband signal of a service signal with the first and the second square wave subcarriers of the service signal to obtain a first binary offset carrier modulation baseband signal and a second binary offset carrier modulation baseband signal; multiplying the first and the second binary offset carrier modulation baseband signals with different amplification factors, so that the power ratio is (1-px)/px; using the first binary offset carrier modulation baseband signal to modulate a first radio frequency carrier to obtain a first radio frequency signal, and meanwhile, using the second binary offset carrier modulation baseband signal to modulate a second radio frequency carrier to obtain a second radio frequency signal; and according to the first and the second radio frequency signals, obtaining the Xth channel radio frequency signal of the service signal. The invention can ensure that the total frequency spectrum of all the channels of a service signal can meet a specific frequency spectrum limiting condition.

Description

Signal modulating method and signal demodulating method

Technical field

The present invention relates generally to signal modulation and demodulation method, more specifically, relate to and being applicable to direct sequence spread spectrum (Direct Sequence Spread Spectrum is designated hereinafter simply as DSSS) signal as the signal modulation and demodulation method in the satellite navigation system of distance measuring signal.

Background technology

Phase overturn comes precise distance measurement in order to utilize in the spreading code frequently, and obtain good multiple access access performance and anti-multipath and jamming performance, GLONASS (Global Navigation Satellite System) (GlobalNavigation Satellite System, be designated hereinafter simply as GNSS) signal all used direct sequence spread spectrum (Direct Sequence Spread Spectrum is designated hereinafter simply as DSSS) technology.Just as known to a person skilled in the art, DSSS can be counted as the expansion of binary phase shift keying (Binary Phase Shift Keying is designated hereinafter simply as BPSK).

Fig. 1 shows the schematic diagram of the baseband waveform of various modulation signals.Wherein, Fig. 1 (a) shows one group of frequency expansion sequence, its by spread-spectrum code chip waveform figuration after, multiply each other with data-signal and radio-frequency carrier, obtain signal transmission.

Traditional navigational range signal adopts binary phase shift keying (Binary Phase Shift Keying-Rectangular the is designated hereinafter simply as BPSK-R) modulation of rectangle spread-spectrum code chip.The chip of the frequency expansion sequence of this base-band spread-spectrum signal is shaped as the rectangle nonreturn to zero code, if the transmission rate of frequency expansion sequence is f _c, then the duration of a Chip Waveform is T _c=1/f _cFig. 1 (b) shows the baseband waveform example of one section sort signal.

The BPSK-R modulation system realizes simple, is widely used in traditional global positioning system (Global Positioning System is designated hereinafter simply as GPS), and what C/A code, P (Y) code used all is this modulation technique.But along with the development of GNSS, the deficiency of the spectral compatibility of this modulation system and range finding and interference free performance manifests day by day.

In order to make multi-signal can share better the limited frequency of GNSS, further improve simultaneously range accuracy and the interference free performance of signal, new signal modulation system constantly presents.The binary offset carrier of for example all knowing in the industry (Binary Offset Carrier is designated hereinafter simply as BOC) modulation.The implementation method of this modulation system is the subcarrier of signal and a square wave form to be multiplied each other on the basis of BPSK-R modulation again, specifically please refer to J.W.Betz " Binary offset carrier modulation for radionavigation ", Navigation, vol.48, pp.227-246, winter 2001-2002.

Known, the BOC modulation has two parameter: subcarrier frequency f _sWith frequency expansion sequence speed f _c, f wherein _s〉=f _cSo the concrete modulation system of BOC can be designated as BOC (f _s, f _c).Fig. 1 (c) has provided one group of base band BOC (2f _c, f _c) waveform example of modulation signal.

In navigation field, simpler notation is with f _sAnd f _cAll carry out normalization with 1.023MHz, directly be designated as BOC (m, n), wherein m=f _s/ 1.023MHz, n=f _c/ 1.023MHz.

A BOC modulation signal can be expressed as:

s _BOC(t)＝A _sd(t)g _BOC(t)cos(2πf ₀t+θ)

Wherein, A _sSignal amplitude, f ₀Be carrier frequency, θ is carrier phase, and d (t) is data-signal,

It is base band BOC modulation signal.

Here, sgn is-symbol function, f _sBe subcarrier frequency, ψ is the phase place of subcarrier, { c _kFrequency expansion sequence, p (t) is to be T the duration _cRectangular pulse, namely

On the basis of BOC modulation, the U.S. and European Union proposed again a kind of new modulation system jointly in 2006, that is, and and multiplexing binary offset carrier (Multiplexed Binary OffsetCarrier is designated hereinafter simply as MBOC) modulation.The global positioning system of the U.S. galileo satellite navigation system developed of Europe of unifying is all used this modulation system on the civil signal of L1/E1 (1575.42MHz) frequency.

In fact strict, the MBOC modulation is not a kind of concrete modulation system, but a more wide in range concept, for the spectral shape of each navigation system signal of constraint.Therefore, only limited the power spectrum shape of signal for the definition of MBOC modulation.A general MBOC signal can be denoted as MBOC (m, n, r), wherein, and m＞n＞0, r 〉=0.Its normalized power spectral density (Power Spectral Density is designated hereinafter simply as PSD) can be expressed as without band limiting filtering the time:

Φ _{MBOC(m，n，r)}＝(1-r)Φ _BOC(n，n)+rΦ _BOC(m，n) (1)

Wherein, Φ _{BOC (n, n)}The power spectrum that adopts the signal of BOC (n, n) modulation, Φ _{BOC (m, n)}It is the power spectrum that adopts the signal of BOC (m, n) modulation.Also namely, to adopt the signal of MBOC modulation be broadband signal BOC (m, n) with narrow band signal BOC (n, n) with power ratio r: (1-r) synthetic obtaining.

Fig. 2 shows the spectral shape of MBOC (6,1,1/11) modulation signal in the 20MHz scope of the center frequency point left and right sides.

Since the definition of MBOC modulation to the concrete methods of realizing of this modulation without any restriction, therefore the component number of signal, the producing method of each component, and the compound mode of each component is very flexible, as long as guarantee that last composite signal PSD satisfies the form of formula (1).The time domain implementation of existing MBOC modulation is not unique yet.The modulation system that the modernized civil signal L1C of GPS L1 frequency uses is called as time division multiplexing binary offset carrier (Time-Multiplexed Binary Offset Carrier is designated hereinafter simply as TMBOC) modulation.Synthetic binary offset carrier (Composite Binary Offset Carrier is designated hereinafter simply as CBOC) modulation and Galileo system L1 serves openly that (Open Service is designated hereinafter simply as OS) signal uses.Implementation about MBOC modulation definition and TMBOC and CBOC modulation, specifically please refer to G.Hein, the people's such as J.Avila-Rodriguez " MBOC:The new optimized spreading modulation recommended forGalileo L1 OS and GPS L1C ", Proc.of IEEE/ION PLANS, San Diego, CA.2006:883-892.Wherein, TMBOC is modulated to the US20080260001 United States Patent (USP).

Just as known to a person skilled in the art, the TMBOC modulation is by time-multiplexed mode BOC (n, n) modulation product and BOC (m, n) modulation product to be made up.The signal of a TMBOC (m, n, r) modulation is launched BOC (m, n) modulation product within some time periods of launch time, launch BOC (n, n) modulation product within remaining time period.The baseband waveform of this modulation signal shown in Fig. 1 (d), shows TMBOC (6f shown in Fig. 1 (d) _c, f _c, 2/11) modulation baseband waveform.

When the time of occurrence ratio of two kinds of signal components was r, the signal power of two components was than being r, and the auto-correlation function of composite signal is:

R _{TMBOC(m，n，r)}＝(1-r)R _BOC(n，n)+rR _BOC(m，n) (2)

Therefore, the PSD of sort signal can satisfy the requirement of MBOC definition.But the deficiency of this modulation system is no matter at transmitting terminal or receiving terminal, the time-multiplexed diverter switch of a cover to be arranged all.

Known, the CBOC modulation is by the mode that time domain linear superposes BOC (n, n) modulation product and BOC (m, n) modulation product to be made up.At all constantly, BOC (n, the n) modulation product of CBOC signal and BOC (m, n) modulation product all occur simultaneously, after tax is with different weights directly by the amplitude addition or subtract each other and be superimposed.Wherein, the value of the two weight has determined the power ratio of BOC (n, n) modulation product and BOC (m, n) modulation product in the final frequency spectrum.

The CBOC modulation signal can be expressed as:

$s_{\mathrm{CBOC}}\left(t\right)=A_{s}d\left(t\right)g_{\mathrm{BPSK}-R}\left(t\right)\cos (2\mathrm{\π}{f}_{0}t+\mathrm{\θ})$

$\×\left\{\sqrt{1-r}\mathrm{sgn}\right[\sin \left(2\mathrm{\π}{f}_{s}t\right)]\±\sqrt{r}\mathrm{sgn}[\sin \left(12\mathrm{\π}{f}_{s}t\right)\left]\right\}$

Wherein, according to when stack BOC (n, n) modulation product with BOC (m, n) modulation product between be addition or subtract each other, the CBOC modulation can be divided into again homophase CBOC modulation and anti-phase CBOC modulates, and is denoted as respectively CBOC ⁺And CBOC ^-Fig. 1 (e) and Fig. 1 (f) show respectively one section CBOC ⁺(6f _c, f _c, 2/11) and waveform example and the CBOC of baseband signal of modulation ^-(6f _c, f _c, 2/11) and the waveform example of baseband signal of modulation.

Known, CBOC ⁺Modulation signal and CBOC ^-The frequency spectrum of modulation signal does not satisfy the definition of MBOC modulation.The frequency spectrum of these two kinds of modulation signals is respectively:

Φ _{CBOC+(m，n，r)}＝(1-r)Φ _BOC(n，n)+rΦ _BOC(m，n)+2r(1-r)Φ _{BOC(n，n)/BOC(m，n)}

Φ _{CBOC-(m，n，r)}＝(1-r)Φ _BOC(n，n)+rΦ _BOC(m，n)-2r(1-r)Φ _{BOC(n，n)/BOC(m，n)}

Wherein, Φ _{BOC (n, n)/BOC (m, n)}It is the spectrum of the cross-correlation between BOC (n, n) modulation product and BOC (m, the n) modulation product.For guaranteeing that total PSD satisfies MBOC definition, in total transmitting, only have the modulation signal constant power of two kinds of CBOC to occur in pairs, the cross-correlation item in total composite signal just can be cancelled out each other.Such restrictive condition makes the use underaction of CBOC modulation.And different from BPSK-R modulation, BOC modulation, TMBOC modulation, the time domain waveform of the signal of CBOC modulation is not two-value, and has a plurality of amplitudes.This equipment complexity that just allows transmitting terminal and receiving terminal produce sort signal increases.Each signal amplitude constantly can not represent with single-bit, and will use a plurality of bits.When in receiver, using logical circuit that sort signal is carried out related operation, many bits multiply each other and cumulative operation all can increase the implementation complexity of receiver greatly.

Summary of the invention

In view of the foregoing, propose the present invention, and then improved the problem that occurs in the prior art guaranteeing that modulation signal satisfies under the condition of MBOC definition.The invention provides a kind of signal modulation and demodulation method, wherein, this signal modulating method is used for making two modulation products of signal of each channel after the modulation mutually orthogonal on carrier phase, so that the total frequency spectrum of all channels of the signal after the modulation satisfies specific spectrum limitations condition, and this signal demodulating method is used for utilizing the cross correlation of frequency expansion sequence to come the signal through above-mentioned signal modulating method modulation is carried out demodulation process.

According to an aspect of the present invention, signal modulating method may further comprise the steps: for the X channel, step 1, the X channel baseband signal of service signal is multiplied each other with the first square wave subcarrier and the second square wave subcarrier of service signal respectively, obtain the first binary offset carrier modulating baseband signal and the second binary offset carrier modulating baseband signal; Step 2 multiply by different amplification with the first binary offset carrier modulating baseband signal and the second binary offset carrier modulating baseband signal, makes their power ratio be (1-p _x)/p _xStep 3 is modulated the first radio-frequency carrier with the first binary offset carrier modulating baseband signal, obtains the first radiofrequency signal, and modulates the second radio-frequency carrier with the second binary offset carrier modulating baseband signal simultaneously, obtains the second radiofrequency signal; And step 4, obtain the X channel radiofrequency signal of service signal according to the first radiofrequency signal and the second radiofrequency signal, wherein, p _xIt is the power ratio of arrowband BOC component described in the X channel and described broadband BOC component, and X represents the channel number of service signal, wherein, m is the square wave subcarrier frequency of broadband BOC component described in the frequency spectrum of described X channel of the described service signal result after by 1.023MHz normalization; N is the square wave subcarrier frequency of arrowband BOC component described in the frequency spectrum of the described X channel result after by 1.023MHz normalization; p _xIt is the power ratio of arrowband BOC component described in the frequency spectrum of described X channel of described service signal and described broadband BOC component; And each m, n, p _xCombination is corresponding to a kind of spectral shape and preseted, and m＞n＞0, p _x〉=0.

Wherein, described predetermined spectrum limitations condition is MBOC (m, n, r).R is the power ratio of arrowband BOC component and broadband BOC component in the total frequency spectrum of service signal, and each m, n, the r combination is corresponding to a kind of spectral shape and preseted, and m＞n＞0, r 〉=0.

This signal modulating method also comprises: for the X channel of service signal, and the binary system frequency expansion sequence that preparation will send; The binary system telegraph text data of the X channel of frequency expansion sequence and service signal is carried out xor operation to be superimposed; And with rectangle nonreturn to zero code waveform to the stack after sequence carry out pulse modulation, thereby obtain the X channel baseband signal of service signal.

Wherein, the binary system frequency expansion sequence is with speed f by Spread Spectrum Number Generator _cThat produce or be stored in advance in the memory and with speed f _cRead f _cBy MBOC (m, n, p _x) parameter n in the spectrum limitations condition determines f _c=n * 1.023MHz.

When the X channel of service signal when not having the channel of binary system telegraph text data modulation, the binary system telegraph text data is got the steady state value logical zero.

The first binary offset carrier modulating baseband signal and the second binary offset carrier modulating baseband signal are placed on the mutually orthogonal phase place of carrier wave to be launched.

In step 3, the first radio-frequency carrier is identical with the frequency of the second radio-frequency carrier, and phase place differs pi/2.

In step 4, the addition by the first radiofrequency signal and the second radiofrequency signal or subtract each other the X channel radiofrequency signal that obtains service signal.

In the situation that have two channels, the first binary offset carrier modulating baseband signal in the X channel and the power ratio p of the second binary offset carrier modulating baseband signal _xWith the first binary offset carrier modulating baseband signal in the Y-channel and the power ratio p of the second binary offset carrier modulating baseband signal _yWhen not waiting, the ratio of the gross power of X channel radiofrequency signal and the gross power of Y-channel radiofrequency signal is (r-p _y)/(p _x-r), wherein, Y represents that another channel number of service signal and value are different from X.

Work as p _x=p _yDuring=r, X signal RF signal equates with the gross power of Y-channel radiofrequency signal.

According to another aspect of the present invention, this signal demodulating method may further comprise the steps: the modulation signal that receives is carried out frequency conversion, sample quantization processing, to obtain digital medium-frequency signal, and digital medium-frequency signal and homophase carrier wave and the quadrature carrier of local reproduction are multiplied each other, to obtain in-phase base band signal and digital orthogonal baseband signal; Produce the frequency expansion sequence identical with wanting the receive channel signal at receiving terminal, and come frequency expansion sequence is carried out pulse code modulation with two symbol waveforms respectively, to obtain respectively local the first baseband signal and local the second baseband signal; In-phase base band signal and digital orthogonal baseband signal are multiplied each other with the first baseband signal and the second baseband signal respectively, and the result is sent into integration remove the coherent integration that filter carries out predetermined length, to obtain the first in-phase correlated value I ₁With the second in-phase correlated value I ₂With the first Orthogonal correlation value Q ₁With the second Orthogonal correlation value Q ₂According to pre-defined rule to the first in-phase correlated value I ₁With the second in-phase correlated value I ₂With the first Orthogonal correlation value Q ₁With the second Orthogonal correlation value Q ₂Make up, to obtain with combined correlation I ' and Orthogonal Composite correlation Q '; And use catching method and track loop to processing with combined correlation I ' and Orthogonal Composite correlation Q ', to obtain the signal after the demodulation.

Wherein, two symbol waveforms are respectively arrowband BOC symbol waveform and broadband BOC symbol waveform.Pre-defined rule is

R is corresponding to the power ratio of two components in the MBOC that wants the receive channel signal to satisfy (m, n, r) the spectrum limitations condition.

Therefore, by modulator approach of the present invention, can make the total frequency spectrum of two channels of a service signal satisfy MBOC (m, n, r) spectrum limitations condition.Adopt the signal of each channel of modulation system of the present invention, all there is not BOC (n in the frequency spectrum, n) modulation product and BOC (m, n) spectrum of the cross-correlation between the modulation product can guarantee that the constant basis of total MBOC spectrum limitations allows different channels adjust flexibly spectral shape and relative power intensity according to different application needs.And by demodulation method of the present invention, the complexity of coupling receiver is suitable with CBOC Signal Matching receiver, and hardware resource expends few.

Description of drawings

Fig. 1 shows the schematic diagram of the baseband waveform of various modulation signals in the prior art.

Fig. 2 shows the spectral shape of MBOC in the prior art (6,1,1/11) modulation signal in the 20MHz scope of the center frequency point left and right sides.

Fig. 3 is the flow chart according to signal modulating method of the present invention.

Fig. 4 is the flow chart according to signal demodulating method of the present invention.

Fig. 5 is the view according to the method for reseptance of the modulation signal of the embodiment of the invention.

Embodiment

Describe below with reference to the accompanying drawings each embodiment of the present invention in detail.

Should be appreciated that, in the present invention, m, the n in MBOC (m, n, r) the spectrum limitations condition, the specific definition of r are:

M is the square wave subcarrier frequency of BOC component in broadband in the MBOC signal result after by 1.023MHz normalization, i.e. m=f _s/ 1.023MHz;

N is the square wave subcarrier frequency of BOC component in arrowband in the MBOC signal result after by 1.023MHz normalization, i.e. n=f _c/ 1.023MHz, and simultaneously n also be the result of spread-spectrum code rate after by 1.023MHz normalization (namely, the MBOC signal is the combination of two kinds of BOC components, the spread-spectrum code rate of two kinds of BOC components all is n * 1.023MHz, but the square wave subcarrier frequency is different, wherein, a kind of square wave subcarrier frequency is m * 1.023MHz, and alternative square wave subcarrier frequency is n * 1.023MHz); And

R is the power ratio of these two kinds of BOC components in the total frequency spectrum.

Particularly, (m, n, r) be a restriction just, and this restriction can be preseted by Design of Signal person, and any one m, n, r make up corresponding to a kind of spectral shape.In addition, (m, n, r) limits also and can just be preseted before the concrete modulation system design of signal, then designs modulation system under the restriction of this design limiting again.

Fig. 3 is the flow chart according to signal modulating method of the present invention.As shown in Figure 3, signal modulating method according to the present invention may further comprise the steps:

For the X channel,

S302 multiplies each other the X channel baseband signal of service signal respectively with the first square wave subcarrier and the second square wave subcarrier of service signal, obtain the first binary offset carrier modulating baseband signal and the second binary offset carrier modulating baseband signal;

S304 multiply by different amplification with the first binary offset carrier modulating baseband signal and the second binary offset carrier modulating baseband signal, makes their power ratio be (1-p _x)/p _x

S306 modulates the first radio-frequency carrier with the first binary offset carrier modulating baseband signal, obtains the first radiofrequency signal, and modulates the second radio-frequency carrier with the second binary offset carrier modulating baseband signal simultaneously, obtains the second radiofrequency signal; And

S308 obtains the X channel radiofrequency signal of service signal according to the first radiofrequency signal and the second radiofrequency signal.

Wherein, p _xBe MBOC (m, n, the p that the X channel will satisfy _x) parameter p in the spectrum limitations condition _xAnd X represents the channel number of service signal.

M is the square wave subcarrier frequency of broadband BOC component in the X channel of the service signal result after by 1.023MHz normalization, and n is the square wave subcarrier frequency of arrowband BOC component in the X channel of the service signal result after by 1.023MHz normalization, p _xThe power ratio of arrowband BOC component and broadband BOC component in the X channel spectrum of service signal, and each m, n, p _xCombination is corresponding to a kind of spectral shape and preseted, and m＞n＞0, p _x〉=0.

In addition, predetermined spectrum limitations condition is MBOC (m, n, r).R is the power ratio of arrowband BOC component described in the total frequency spectrum of described service signal and described broadband BOC component, and each m, n, the r combination is corresponding to a kind of spectral shape and preseted, and m＞n＞0, r 〉=0.

This signal modulating method also comprises: for the X channel of service signal, and the binary system frequency expansion sequence that preparation will send; The binary system telegraph text data of the X channel of frequency expansion sequence and service signal is carried out xor operation to be superimposed; And with rectangle nonreturn to zero code waveform to the stack after sequence carry out pulse modulation, thereby obtain the X channel baseband signal of service signal.

Wherein, the binary system frequency expansion sequence is with speed f by Spread Spectrum Number Generator _cThat produce or be stored in advance in the memory and with speed f _cRead f _cBy MBOC (m, n, p _x) parameter n in the spectrum limitations condition determines f _c=n * 1.023MHz.

When the X channel of service signal when not having the channel of binary system telegraph text data modulation, the binary system telegraph text data is got the steady state value logical zero.

The first binary offset carrier modulating baseband signal and the second binary offset carrier modulating baseband signal are placed on the mutually orthogonal phase place of carrier wave to be launched.

In S306, the first radio-frequency carrier is identical with the frequency of the second radio-frequency carrier, and phase place differs pi/2.

In S308, the addition by the first radiofrequency signal and the second radiofrequency signal or subtract each other the X channel radiofrequency signal that obtains service signal.

There are two channels at service signal, and the total frequency spectrum of this service signal is defined and satisfies MBOC (m, n, r) in the situation of spectrum limitations condition, the first binary offset carrier modulating baseband signal in the X channel and the power ratio p of the second binary offset carrier modulating baseband signal _xWith the first binary offset carrier modulating baseband signal in the Y-channel and the power ratio p of the second binary offset carrier modulating baseband signal _yWhen not waiting, the ratio of the gross power of X channel radiofrequency signal and the gross power of Y-channel radiofrequency signal is (r-p _y)/(p _x-r), wherein, Y represents that another channel number of service signal and value are different from X, and p _x, p _yBe predetermined value.

Work as p _x=p _yDuring=r, X signal RF signal equates with the gross power of Y-channel radiofrequency signal.

Should be appreciated that, in some satellite navigation systems, same carrier wave can transmit the signal of a plurality of channels simultaneously, with for different application.For example, can use same road carrier wave to transmit simultaneously first service signal and second service signal, and the first service signal comprises two channels, be called first service signal the first channel and first service signal second channel, the second service signal also comprises two channels, is called second service signal the first channel and second service signal second channel.The frequency expansion sequence of these four channels is orthogonal.The signal of these four channels is combined into the composite signal of a constant-envelope by certain multiplex mode.For example, the first service signal is the OS signal that does not have encryption, and the second service signal is the public administration service signal that need to license, and two signals all comprise data channel and these two channels of pilot channel.

Yet, should be appreciated that, in fact service signal is not limited only to comprise two channels, and the selection of channel number is set according to application fully.

In the present invention, comprise respectively two channels as example take first service signal and second service signal, certainly, this only is a kind of typical case, and each service signal can only comprise a channel or comprise a plurality of channels.

In specific embodiment, two channels of first service signal all use according to modulator approach of the present invention, thereby make two total frequency spectrums of channel satisfy MBOC (m, n, r) spectrum limitations condition.

It will be understood by a person skilled in the art that, because two total frequency spectrums of channel of first service signal satisfy MBOC (m, n, r) spectrum limitations condition, therefore two channels frequency spectrum separately can but must all not satisfy MBOC (m, n, r) spectrum limitations condition.

For example, can allow the frequency spectrum of first service signal the first channel signal and first service signal second channel all satisfy MBOC (m, n, r) restrictive condition, the power ratio of two channels can arbitrarily arrange and can allow total frequency spectrum satisfy MBOC (m, n, r) spectrum limitations condition at this moment.Yet, also can allow first service signal the first channel signal frequency spectrum satisfy MBOC (m, n, p) restrictive condition, p ≠ r, and first service signal second channel signal spectrum satisfies MBOC (m, n, q) restrictive condition, q ≠ r also is BOC (m, n) component and BOC (n in first service signal the first channel signal, n) power ratio of component is p/ (1-p), and this ratio is q/ (1-q) in the second channel.In this case, as long as the power ratio of two channels is (r-q)/(p-r), still can make two total frequency spectrums of channel satisfy MBOC (m, n, r) spectrum limitations condition.

To first service signal the first channel, at first prepare out the binary system frequency expansion sequence { c that will send _k, frequency expansion sequence can be in real time by Spread Spectrum Number Generator with speed f _cProduce, also can be stored in advance in the memory, with speed f _cRead.F wherein _cChoose by the parameter n in MBOC (m, n, p) the spectrum limitations condition and determine that f is arranged _c=n * 1.023MHz.

Frequency expansion sequence { c _kBe superimposed by the logic xor operation with the binary system telegraph text data of first service signal the first channel, the sequence after the stack is carried out pulse code modulation by rectangle nonreturn to zero code waveform, obtains first service signal the first channel baseband signal S ₁(t).Those skilled in that art are appreciated that for example pilot channel can be regarded as the situation that the binary system telegraph text data is got the steady state value logical zero if first service signal the first channel correspondence does not have the channel of binary system telegraph text data modulation.

First service signal the first channel baseband signal is multiplied each other with first service signal the first square wave subcarrier and first service signal the second square wave subcarrier respectively, and wherein, the first square wave subcarrier can be written as S _Sc1(t)=sgn[sin (2 π f _cT+ ψ ₁)], the second square wave subcarrier can be written as S _Sc2(t)=sgn[sin (2 π f _sT+ ψ ₂)], obtain first service signal the first channel the first binary offset carrier modulating baseband signal S _{BOC (fc, fc) 1}(t) and first service signal the first channel the second binary offset carrier modulating baseband signal S _{BOC (fs, fc) 1}(t), expression formula is:

S _{BOC(fc，fc)1}(t)＝S ₁(t)sgn[sin(2πf _ct+ψ ₁)]

S _{BOC(fs，fc)1}(t)＝S ₁(t)sgn[sin(2πf _st+ψ ₂)]

Wherein, f _sThe frequency of expression first service signal the second square wave subcarrier determines that by the parameter m in MBOC (m, n, p) the spectrum limitations condition f is arranged _s=m * 1.023MHz.Fc is the generation speed of frequency expansion sequence, also is the frequency of the first square wave subcarrier simultaneously.

By these two binary offset carrier modulating baseband signals be multiply by different multiplication factors, with the first binary offset carrier modulating baseband signal S _{BOC (fc, fc) 1}(t) amplitude is adjusted to A _S11, the second binary offset carrier modulating baseband signal S _{BOC (fs, fc) 1}(t) amplitude is adjusted to A _S12, so that S _{BOC (fc, fc) 1}(t) and S _{BOC (fs, fc) 1}(t) power ratio is (1-p)/p.

Processing method to first service signal second channel is similar, at first binary system frequency expansion sequence and telegraph text data are superimposed by the logic xor operation, and use rectangle nonreturn to zero code waveform to carry out pulse code modulation, obtain first service signal second channel baseband signal S ₂(t).Those skilled in that art are appreciated that for example pilot channel can be regarded as the situation that the binary system telegraph text data is got the steady state value logical zero if first service signal second channel correspondence does not have the channel of binary system telegraph text data modulation.Afterwards respectively with first service signal the first square wave subcarrier S _Sc1(t) and first service signal the second square wave subcarrier S _Sc2(t) multiply each other, obtain first service signal second channel the first binary offset carrier modulating baseband signal S _{BOC (fc, fc) 2}(t) and first service signal second channel the second binary offset carrier modulating baseband signal S _{BOC (fs, fc) 2}(t).Afterwards, by these two binary offset carrier modulating baseband signals be multiply by different multiplication factors, with the first binary offset carrier modulating baseband signal S _{BOC (fc, fc) 2}(t) amplitude is adjusted to A _S21, the second binary offset carrier modulating baseband signal S _{BOC (fs, fc) 2}(t) amplitude is adjusted to A _S22, so that S _{BOC (fc, fc) 2}(t) and S _{BOC (fs, fc) 2}(t) power ratio is (1-q)/q.

For first service signal the first channel and second channel, modulation system of the present invention all is placed on the first binary offset carrier modulating baseband signal and the second binary offset carrier modulating baseband signal on a pair of mutually orthogonal phase place of carrier wave launches.

To the first channel, can use the first binary offset carrier modulating baseband signal to modulate the first radio-frequency carrier

Obtain the first RF signal S _RF11(t).Simultaneously, use the second binary offset carrier modulating baseband signal to modulate the second radio-frequency carrier Obtain the second RF signal S _RF12(t).Wherein, f _RFBe carrier frequency,

It is the first channel original carrier phase place.The first radio-frequency carrier is identical with the second radio frequency carrier frequency, and phase place differs pi/2.

The first radiofrequency signal and the second radiofrequency signal are by addition or subtract each other the radiofrequency signal that obtains first service signal the first channel, and its mathematical expression can be expressed as:

${\tilde{s}}_1\left(t\right)=A_{s11}{S}_{\mathrm{BOC}(f_c,f_c)1}\left(t\right)\cos (2\mathrm{\π}{f}_{\mathrm{RF}}t+{\mathrm{\φ}}_1)\±A_{s12}{S}_{\mathrm{BOC}(f_s,f_c)1}\left(t\right)\sin (2\mathrm{\π}{f}_{\mathrm{RF}}t+{\mathrm{\φ}}_1)$

To first service signal second channel, use equally the first binary offset carrier modulating baseband signal to modulate the first radio-frequency carrier

Obtain second channel the first RF signal S _RF21(t).Simultaneously, use the second binary offset carrier modulating baseband signal to modulate the second radio-frequency carrier

Obtain second channel the second RF signal S _RF22(t).Second channel the first radiofrequency signal and second channel the second radiofrequency signal are by addition or subtract each other the radiofrequency signal that obtains first service signal second channel, and its mathematical expression can be expressed as:

${\tilde{s}}_2\left(t\right)=A_{s21}{S}_{\mathrm{BOC}(f_c,f_c)2}\left(t\right)\cos (2\mathrm{\π}{f}_{\mathrm{RF}}t+{\mathrm{\φ}}_2)\±A_{s22}{S}_{\mathrm{BOC}(f_s,f_c)2}\left(t\right)\sin (2\mathrm{\π}{f}_{\mathrm{RF}}t+{\mathrm{\φ}}_2)$

Total first service signal of therefore, finally broadcasting comprises the first radiofrequency signal and the second radiofrequency signal.And for the frequency spectrum of total first service signal of guaranteeing finally to broadcast satisfies MBOC (m, n, r) restrictive condition, when p ≠ r, in total first service signal of finally broadcasting, the first channel radiofrequency signal power P ₁With second channel radiofrequency signal power P ₂Ratio be (r-q)/(p-r).When p=q=r, two channel radiofrequency signal power equate.

It will be understood by a person skilled in the art that, modulator approach of the present invention is that the first square wave subcarrier in the radiofrequency signal of each channel and the second square wave subcarrier are placed on two mutually orthogonal phase places of carrier wave.Also can be quadrature and the relative phase of these two channel signals can be homophase, depending on

With

Relative value and decide.

With

Differ 0 or during π, the component of modulation the first square wave subcarrier is in together on the same phase place of carrier wave in two channel signals, when

With

When differing pi/2, the component of modulation the first square wave subcarrier divides on the phase place that two of being in carrier wave differ pi/2 in two channel signals.

Should be appreciated that, adopt the signal of each channel of modulation system of the present invention, all do not have the spectrum of the cross-correlation between BOC (n, n) modulation product and BOC (m, the n) modulation product in the frequency spectrum.This is because these two modulation products are orthogonal on carrier wave.

Therefore, adopt modulation system of the present invention, the power of each channel need not to equate in the service signal, and each channel signal does not need carrier phase identical yet.For example, in one embodiment, when having two channels, in order to allow total frequency spectrum satisfy MBOC (6,1,1/11) restriction can allow the first channel of first service signal and the power ratio of second channel get 3/1, and then the first channel satisfies MBOC (6,1,1/33) spectrum limitations, second channel satisfy MBOC (6,1,3/11) spectrum limitations, although each channel does not satisfy the total frequency spectrum restriction of MBOC (6,1,1/11), but total frequency spectrum satisfies MBOC (6,1,1/11) restriction, and the carrier phase of the signal of these two channels can be identical also can be orthogonal.

Thereby, adopt modulation system of the present invention can realize modulating more flexibly channel power proportioning and channel relative phase relation than CBOC.Those skilled in that art are appreciated that different MBOC spectrum limitations so that the range accuracy of signal, demodulation threshold, anti-multipath and interference performance have different.Use modulation system of the present invention guaranteeing that the constant basis of total MBOC spectrum limitations allows different channels adjust flexibly spectral shape and relative power intensity according to different application needs.

Fig. 4 is the flow chart according to signal demodulating method of the present invention.As shown in Figure 4, signal demodulating method according to the present invention may further comprise the steps:

S402 carries out frequency conversion, sample quantization with the modulation signal that receives and processes, and obtaining digital medium-frequency signal, and digital medium-frequency signal and homophase carrier wave and the quadrature carrier of local reproduction is multiplied each other, to obtain in-phase base band signal and digital orthogonal baseband signal;

S404 produces the frequency expansion sequence identical with wanting the receive channel signal at receiving terminal, and comes frequency expansion sequence is carried out pulse code modulation with two symbol waveforms respectively, to obtain respectively local the first baseband signal and local the second baseband signal;

S406 multiplies each other respectively in-phase base band signal and digital orthogonal baseband signal with the first baseband signal and the second baseband signal, and the result is sent into integration remove the coherent integration that filter carries out predetermined length, to obtain the first in-phase correlated value I ₁With the second in-phase correlated value I ₂With the first Orthogonal correlation value Q ₁With the second Orthogonal correlation value Q ₂

S408, according to pre-defined rule to the first in-phase correlated value I ₁With the second in-phase correlated value I ₂With the first Orthogonal correlation value Q ₁With the second Orthogonal correlation value Q ₂Make up, to obtain with combined correlation I ' and Orthogonal Composite correlation Q '; And

S410 uses catching method and track loop to processing with combined correlation I ' and Orthogonal Composite correlation Q ', to obtain the signal after the demodulation.

Wherein, two symbol waveforms are respectively arrowband BOC symbol waveform and broadband BOC symbol waveform.Pre-defined rule is

R is corresponding to the power ratio of two components in the MBOC that wants the receive channel signal to satisfy (m, n, r) the spectrum limitations condition.

In an embodiment of the present invention because two channels of first service signal use orthogonal frequency expansion sequences, so known, utilization be the good cross correlation of frequency expansion sequence, that is, at receiving terminal, receiver can be processed respectively the signal of two channels.

Fig. 5 is the view according to the method for reseptance of the modulation signal of the embodiment of the invention.As shown in Figure 5, the signal that receives becomes digital medium-frequency signal after through down-conversion, sample quantization.Intermediate-freuqncy signal s _IFAt first with homophase (I), quadrature (Q) carrier multiplication of this locality reproduction, obtain in-phase base band signal s _IWith digital orthogonal baseband signal s _QReceiver is inner to produce the frequency expansion sequence identical with wanting the receive channel signal, and uses respectively BOC (m, n) symbol waveform and BOC (n, n) symbol waveform that it is carried out pulse code modulation, obtains respectively local the first baseband signal s ₁With local the second baseband signal s ₂

In-phase base band signal s _IWith local the first baseband signal s ₁Multiply each other, send into integration and remove (I﹠amp; D) to carry out length be T to filter _ICoherent integration, obtain the first in-phase correlated value I1; In-phase base band signal s _IWith local the second baseband signal s ₂Multiply each other, send into integration and remove (I﹠amp; D) to carry out length be T to filter _ICoherent integration, obtain the second in-phase correlated value I ₂

Digital orthogonal baseband signal s _QWith local the first baseband signal s ₁Multiply each other, send into integration and remove (I﹠amp; D) to carry out length be T to filter _ICoherent integration, obtain the first Orthogonal correlation value Q ₁Digital orthogonal baseband signal s _QWith local the second baseband signal s ₂Multiply each other, send into integration and remove (I﹠amp; D) to carry out length be T to filter _ICoherent integration, obtain the second Orthogonal correlation value Q ₂

Four road correlation I ₁, I ₂, Q ₁, Q ₂Make up according to following rule, obtain with combined correlation I ' and Orthogonal Composite correlation Q ', wherein, rule is:

$\left\{\begin{array}{c}{I}^{\&prime;}=\sqrt{1-\mathrm{<figure-callout\; id="2"\; label="r\; I"\; filenames="HSA00000133175700011.png,HSA00000133175700012.png"\; state="\{\{state\}\}">r</figure-callout>}}{I}_{}{}_2+\sqrt{r}{Q}_1\\ Q^{\&prime;}=\sqrt{r}{I}_1-\sqrt{1-\mathrm{<figure-callout\; id="2"\; label="r\; Q"\; filenames="HSA00000133175700011.png,HSA00000133175700012.png"\; state="\{\{state\}\}">r</figure-callout>}}{Q}_{}{}_2\end{array}\right.$

Wherein, two component power ratios in MBOC (m, n, the r) restriction that will satisfy of corresponding this channel signal of r.

Same combined correlation I ' and Orthogonal Composite correlation Q ' after the merging can use traditional catching method and track loop to process.

Therefore, compare with the coupling method of reseptance of TMBOC signal, use the receiver of modulation signal of the present invention to save time-multiplexed commutation circuit in this locality.And compare with CBOC Signal Matching receiver, when the CBOC receiver directly produces many-valued amplitude CBOC signal with many bits in this locality, although its required I﹠amp; D filter quantity is the used I﹠amp of demodulation method according to the present invention; Half of D filter, but many bits multiply each other and expend obviously much higher than demodulation method of the present invention with cumulative hardware resource.Express for 1 bit that reaches local spread-spectrum signal, the CBOC receiver equally need to be with I﹠amp; D filter quantity doubles and again weighting merging after integration is finished.This shows, coupling Receiver Complexity of the present invention is suitable with CBOC Signal Matching receiver.

The above is the preferred embodiments of the present invention only, is not limited to the present invention, and for a person skilled in the art, the present invention can have various modifications and variations.Within the spirit and principles in the present invention all, any modification of doing, be equal to replacement, improvement etc., all should be included within protection scope of the present invention.

Claims (9)

1. signal modulating method, be used for making broadband binary offset carrier component and the arrowband binary offset carrier component of signal of each channel after the modulation mutually orthogonal on carrier phase, so that the total frequency spectrum of all channels of the signal after the modulation satisfies predetermined spectrum limitations condition, it is characterized in that, described signal modulating method may further comprise the steps:

For the X channel,

Step 1 multiplies each other the X channel baseband signal of service signal respectively with the first square wave subcarrier and the second square wave subcarrier of described service signal, obtain the first binary offset carrier modulating baseband signal and the second binary offset carrier modulating baseband signal;

Step 2 multiply by different amplification with described the first binary offset carrier modulating baseband signal and described the second binary offset carrier modulating baseband signal, makes their power ratio be (1-p _x)/p _x

Step 3, modulate the first radio-frequency carrier with described the first binary offset carrier modulating baseband signal, obtain the first radiofrequency signal, and modulate the second radio-frequency carrier with described the second binary offset carrier modulating baseband signal simultaneously, obtain the second radiofrequency signal; And

Step 4, obtain the X channel radiofrequency signal of described service signal according to described the first radiofrequency signal and described the second radiofrequency signal, be specially the addition by described the first radiofrequency signal and described the second radiofrequency signal or subtract each other the X channel radiofrequency signal that obtains described service signal

Wherein, p _xRepresent MBOC (m, n, p that described X channel will satisfy _x) a parameter in the spectrum limitations condition, and X represents the channel number of service signal,

Wherein, m is the square wave subcarrier frequency of broadband binary offset carrier component described in the frequency spectrum of described X channel of the described service signal result after by 1.023MHz normalization; N is the square wave subcarrier frequency of arrowband binary offset carrier component described in the frequency spectrum of the described X channel result after by 1.023MHz normalization; p _xIt is the power ratio of arrowband binary offset carrier component described in the frequency spectrum of described X channel of described service signal and described broadband binary offset carrier component; And

Each m, n, p _xCombination is corresponding to a kind of spectral shape and preseted, and m＞n＞0, p _x〉=0;

Described predetermined spectrum limitations condition is MBOC (m, n, r), wherein,

R is the power ratio of arrowband binary offset carrier component described in the total frequency spectrum of described service signal and described broadband binary offset carrier component, and

Each m, n, r make up corresponding to a kind of spectral shape and are preseted, and m＞n＞0, r 〉=0.

2. signal modulating method according to claim 1 is characterized in that, and is further comprising the steps of:

For the described X channel of described service signal, the binary system frequency expansion sequence that preparation will send;

The binary system telegraph text data of the described X channel of described frequency expansion sequence and described service signal is carried out xor operation to be superimposed; And

With rectangle nonreturn to zero code waveform the sequence after superposeing is carried out pulse modulation, thereby obtain the X channel baseband signal of described service signal.

3. signal modulating method according to claim 2 is characterized in that,

Described binary system frequency expansion sequence is with speed f by Spread Spectrum Number Generator _cThat produce or be stored in advance in the memory and with speed f _cRead,

Wherein, f _cBy MBOC (m, n, p _x) parameter n in the spectrum limitations condition determines f _c=n * 1.023MHz.

4. signal modulating method according to claim 2 is characterized in that, when the described X channel of described service signal when not having the channel of binary system telegraph text data modulation, described binary system telegraph text data is got the steady state value logical zero.

5. signal modulating method according to claim 1 is characterized in that, described the first binary offset carrier modulating baseband signal and described the second binary offset carrier modulating baseband signal are placed on the mutually orthogonal phase place of carrier wave to be launched.

6. signal modulating method according to claim 1 is characterized in that, in described step 3,

Described the first radio-frequency carrier is identical with the frequency of described the second radio-frequency carrier, and phase place differs pi/2,

Addition by described the first radiofrequency signal and described the second radiofrequency signal or subtract each other the X channel radiofrequency signal that obtains described service signal.

7. signal modulating method according to claim 1 is characterized in that, in the situation that have two channels,

Described the first binary offset carrier modulating baseband signal in described X channel and the power ratio p of described the second binary offset carrier modulating baseband signal _xWith described the first binary offset carrier modulating baseband signal in the Y-channel and the power ratio p of described the second binary offset carrier modulating baseband signal _yWhen not waiting,

The ratio of the gross power of described X channel radiofrequency signal and the gross power of Y-channel radiofrequency signal is (r-p _y)/(p _x-r),

Wherein, Y represents that another channel number of service signal and value are different from X.

8. signal modulating method according to claim 7 is characterized in that, works as p _x=p _yDuring=r, described X signal RF signal equates with the gross power of described Y-channel radiofrequency signal.

9. a signal demodulating method is used for utilizing the cross correlation of frequency expansion sequence to come the signal through each modulation of claim 1 to 8 is carried out demodulation process, it is characterized in that, described signal demodulating method may further comprise the steps:

The modulation signal that receives is carried out frequency conversion, sample quantization process, obtaining digital medium-frequency signal, and described digital medium-frequency signal and homophase carrier wave and the quadrature carrier of local reproduction are multiplied each other, to obtain in-phase base band signal and digital orthogonal baseband signal;

Produce the frequency expansion sequence identical with wanting the receive channel signal at receiving terminal, and come described frequency expansion sequence is carried out pulse code modulation with arrowband BOC symbol waveform and broadband BOC symbol waveform respectively, to obtain respectively local the first baseband signal and local the second baseband signal;

Described in-phase base band signal and described digital orthogonal baseband signal are multiplied each other with described the first baseband signal and described the second baseband signal respectively, and the result is sent into integration remove the coherent integration that filter carries out predetermined length, to obtain the first in-phase correlated value I ₁With the second in-phase correlated value I ₂With the first Orthogonal correlation value Q ₁With the second Orthogonal correlation value Q ₂

According to pre-defined rule to described the first in-phase correlated value I ₁With described the second in-phase correlated value I ₂With described the first Orthogonal correlation value Q ₁With described the second Orthogonal correlation value Q ₂Make up, obtaining with combined correlation I ' and Orthogonal Composite correlation Q ', described pre-defined rule is

Wherein, r is corresponding to the power ratio of two components in the MBOC that wants the receive channel signal to satisfy (m, n, r) the spectrum limitations condition; And

Use catching method and track loop to process with combined correlation I ' and described Orthogonal Composite correlation Q ' described, to obtain the signal after the demodulation.

Images