CN102565828A - Method for reducing signal emitting power of satellite navigation and positioning system - Google Patents

Abstract

The invention relates to a method for reducing the signal emitting power of a satellite navigation and positioning system. According to the method, other generation processes and links of a navigation signal are not changed, and only the generation and the modulation mode of spread spectrum codes of the navigation signal are changed, so that the emitting power spectral density within the effective bandwidth of the navigation signal is reasonably and effectively utilized, and the purpose of reducing the signal emitting power is achieved. Namely, the code clock frequency of a medium high long precision code in the spread spectrum codes of the navigation signal is N times of that of a short c/a (coarse/acquisition) code; if the code clock frequency of the short c/a code is improved by N times, and at the same time the cycle period of the short a/c code remains unchanged, the number of spectrum lines of the spread spectrum signal can increased by N times and the height of the spectrum lines can reduced by N decibels under the condition that the overall power remains unchanged, so that the short precision code is formed. Therefore, when the long precision code and the short precision code are added respectively on two orthogonal branches and the modulation to carrier waves are performed simultaneously, the height of the frequency spectrum is the same as that during independent modulation of the long precision code or the short precision code.

Description

A kind of method that is used for satellite navigation and location system reduction signal transmission power

Technical field

The present invention relates to a kind of method that satellite navigation and location system reduces signal transmission power that is used for, be particularly useful under the limited condition of signal transmission power.

Background technology

Each worldwide navigation positioning system (Global Navigation Satellite System; GNSS); Like the GALILEO and the Muscovite GLONASS in GPS of USA, Europe, efficient, the comprehensive utilization of own unique signal transmission power all can be arranged according to self the difference of system architecture, locator meams and modulation system.

External GNSS system all adopts spread-spectrum modulation technique at present, analyzes from the angle of signal power spectral density function, and GNSS navigation signal band spectrum modulation power spectral density function directly affects the effective distribution and the utilization of signal transmission power; And the design of spreading code is the core technology of band spectrum modulation with generating.

Employed spreading code mainly contains two kinds in the external GNSS system: short and thick sign indicating number and long smart sign indicating number.The multiple cycle of short and thick code weight is short, be easy to the GNSS receiver acquisition, but bearing accuracy is low; The multiple cycle of long smart code weight is long, need under the guiding of short and thick sign indicating number, to grow catching of smart sign indicating number, but bearing accuracy is high.Because these two kinds of spreading codes exist complementary preferably, so often they are modulated at collocation use on two quadrature branch of same carrier wave respectively.

In Project Realization, the size of satellites transmits power is that the highest spectral line with satellite emission signal reaches some threshold values and is used as criterion.The sign indicating number clock frequency of short and thick sign indicating number is lower, and the power concentration of signal is on than the minority spectral line in the narrow-band, and spreading code clock frequency is low more, and height of spectral line is high more, and actual required emissive power is high more; And the sign indicating number clock frequency of long smart sign indicating number is higher, and the power of signal is dispersed on the numerous spectral lines in the broad frequency band, and spreading code clock frequency is high more, and height of spectral line is low more, and actual required emissive power is low more.Therefore, launch the required higher-wattage of short and thick sign indicating number and raised the required overall emitted power that transmits, compare, formed the waste of emissive power with the required lower-wattage of the long smart sign indicating number of emission, as shown in Figure 1.

Summary of the invention

The technical matters that solves

For fear of the weak point of prior art, the present invention proposes a kind of method that satellite navigation and location system reduces signal transmission power that is used for, overcome signal produce with emission process in because short and thick yard required higher-wattage of emission causes the waste of emissive power.

Technical scheme

A kind of method that is used for satellite navigation and location system reduction signal transmission power is characterized in that step is following:

Step 1 generates navigation message: press navigation message design and array format, generate navigation message bit information P _Data

Step 2 generates long smart sign indicating number: the generation cycle period is T _{Long_code}Second, speed is F _{Long_code}Chip lengths is L in the MHz, cycle period _{Long_code}=T _{Long_code}* F _{Long_code}Long smart sign indicating number P _{Long_code}=X ₁+ X ₂, wherein, symbol "+" expression mole adds computing, X ₁And X ₂Represent the polynomial expression that two pseudo-random sequences generate;

Step 3 generates short smart sign indicating number: the speed of definite short smart sign indicating number is consistent with long essence sign indicating number to be F _{Long_code}MHz, the sign indicating number cycle T _{Short_code}T satisfies condition _{Short_code}＜T _{Long_code}/ 10, chip lengths is L _{Short_code}=T _{Short_code}* F _{Long_code}, its short smart sign indicating number P _{Short_code}=X ' ₁+ X ' ₂, wherein, symbol "+" expression mole adds computing, X ' ₁, X ' ₂Be respectively by X ₁, X ₂The pseudo-random sequence that generator polynomial produces is pressed L _{Short_code}Length brachymemma gained;

Step 4 band spectrum modulation: navigation message bit information is carried out band spectrum modulation with long smart sign indicating number and short smart sign indicating number respectively, obtain long smart sign indicating number modulated spread spectrum signal S respectively _LongWith short smart sign indicating number modulated spread spectrum signal S _Short:

S _long＝P _{long_code}+P _data

S _short＝P _{short_code}+P _data

Step 5 carrier modulation: adopt carrier signal S _CarrierTo the long smart sign indicating number modulated spread spectrum signal S that generates _LongWith short smart sign indicating number modulated spread spectrum signal S _ShortCarry out carrier modulation, accomplish spread-spectrum signal frequency spectrum moving on carrier wave frequency range, obtain the modulation signal of satellite navigation and location system emission:

S _signal1＝S _long*S _carrier

S _signal2＝S _short*S _carrier

The computing of symbol " * " expression numerical multiplication.

Beneficial effect

A kind of method that is used for satellite navigation and location system reduction signal transmission power that the present invention proposes; Do not change other generative process and link of navigation signal; The generation and the modulation system that only change the navigation signal spreading code realize utilizing the transmit power spectral density in the navigation signal effective bandwidth rationally and effectively, thereby reach the purpose that reduces signal transmission power.Promptly; The N that high long smart sign indicating number sign indicating number clock frequency is short and thick sign indicating number in the navigation signal spreading code doubly if the sign indicating number clock frequency of short and thick sign indicating number is improved N doubly, keeps the cycle period of short and thick sign indicating number constant simultaneously; Under the constant condition of general power; The spectral line radical of spread-spectrum signal can increase N doubly, and the height of spectral line can reduce the N decibel, thereby forms short smart sign indicating number.Like this, when long smart sign indicating number and short smart sign indicating number are added in respectively when simultaneously carrier wave being modulated on the pairwise orthogonal branch road, be the same when the height of frequency spectrum and the long smart sign indicating number of modulation separately or short smart yard.

The invention has the beneficial effects as follows: short smart sign indicating number is that a kind of code length is shorter, and code check is than higher ranging code.It has adopted the speed of smart sign indicating number, the code length of thick sign indicating number, and it is short that therefore short smart sign indicating number had both absorbed thick sign indicating number code length, and the advantage that is prone to catch has absorbed the high advantage of smart sign indicating number bearing accuracy again.It is a kind of high performance ranging code.Short smart sign indicating number uses with long smart sign indicating number collocation; Replaced the collocation use of short and thick sign indicating number and long smart sign indicating number in the traditional GNSS system; Can reduce the required overall emitted power of signal effectively, help rationally, effectively utilize signal transmission power, practice thrift entire system power consumption and cost.

Description of drawings

Fig. 1 is that long smart required emissive power of sign indicating number and the required emissive power of short and thick sign indicating number compare synoptic diagram

Fig. 2 is long smart code generating method synoptic diagram

Fig. 3 is short smart code generating method synoptic diagram

Fig. 4 is the required emissive power synoptic diagram of short smart sign indicating number

Fig. 5 is the required emissive power synoptic diagram of long smart sign indicating number

Embodiment

Combine embodiment, accompanying drawing that the present invention is further described at present:

In the embodiment of the invention, adopt regional positioning system (China Area Positioning System is called for short CAPS), the implementation process of the short-and-medium smart code generating method of worldwide navigation positioning system spreading code that the present invention proposes to be described as relying on platform.The practical implementation step is following:

Step 1: generate navigation message:

Press navigation message design and array format, under the effect of navigation information speed clock signal, from formation, read navigation message bit information P successively _Data, prepare to carry out mole and add calculation process with spreading code.

In the present embodiment, navigation message information P is set _DataSpeed is F _Data=50Hz.

Step 2: generate long smart sign indicating number

Confirm the generation method of long smart sign indicating number.If long smart sign indicating number cycle period is T _{Long_code}Second, long smart bit rate is F _{Long_code}MHz, then the interior chip lengths of long smart sign indicating number cycle period is L _{Long_code}=T _{Long_code}* F _{Long_code}

Long smart sign indicating number generative process is as shown in Figure 2.

By Fig. 2, long smart sign indicating number generator polynomial is used P _{Long_code}Expression, two pseudo-random sequence generator polynomials are used X respectively ₁, X ₂Expression, then: P _{Long_code}=X ₁+ X ₂, wherein, symbol "+" expression mole adds computing.

In the present embodiment, it is T that the long smart sign indicating number cycle is set _{Long_code}=1 second, bit rate was F _{Long_code}=10.23MHz, then a long smart interior chip lengths of sign indicating number cycle is L _{Long_code}=T _{Long_code}* F _{Long_cod}=10230000.

In the present embodiment, X ₁Generator polynomial is expressed as X ₁=x ¹⁵+ x ¹⁴+ 1, X ₂Generator polynomial is expressed as X ₂=x ¹⁵+ x ¹⁴+ x ¹²+ x ³+ 1, then long smart sign indicating number generator polynomial P _{Long_code}=X ₁+ X ₂, symbol "+" expression mole adds computing.

Step 3: generate short smart sign indicating number

According to the sign indicating number cycle and the bit rate of long smart sign indicating number, confirm that the sign indicating number cycle of short smart sign indicating number is T _{Short_code}Second, and T _{Short_code}T satisfies condition _{Short_code}＜T _{Long_code}/ 10, bit rate still is F _{Long_code}MHz, then a short smart interior chip lengths of sign indicating number cycle is L _{Short_code}=T _{Short_code}* F _{Long_code}

According to the generation method of long smart sign indicating number, short smart code generating method is as shown in Figure 3.

By Fig. 3, short smart sign indicating number generator polynomial is used P _{Short_code}Expression, two pseudo-random sequence generator polynomials are used X ' respectively ₁, X ' ₂Expression, then: P _{Short_code}=X ' ₁+ X ' ₂, wherein, symbol "+" expression mole adds computing, X ' ₁, X ' ₂Be respectively by X ₁, X ₂The pseudo-random sequence that generator polynomial produces is pressed L _{Short_code}Length brachymemma gained.

P _{Short_code}Be the short smart sign indicating number of generation.

In the present embodiment,, confirm that the sign indicating number cycle of short smart sign indicating number is T according to the sign indicating number cycle and the bit rate of long smart sign indicating number _{Short_code}=1*10 ^-3Second, bit rate still is F _{Long_code}=10.23MHz, then a short smart interior chip lengths of sign indicating number cycle is L _{Short_code}=T _{Short_code}* F _{Long_code}=10230.

By the smart code generating method of weak point shown in Figure 3, in the present embodiment, X ' ₁Generator polynomial is expressed as X ' ₁=x ¹⁵+ x ¹⁴+ 1, X ' ₂Generator polynomial is expressed as X ' ₂=x ¹⁵+ x ¹⁴+ x ¹²+ x ³+ 1, then short smart sign indicating number generator polynomial P _{Short_code}=X ' ₁+ X ' ₂, symbol "+" expression mole adds computing, X ' ₁, X ' ₂Original state setting and X ₁, X ₂Identical.

Step 4: band spectrum modulation

Navigation message bit information is carried out band spectrum modulation with long smart sign indicating number and short smart sign indicating number respectively, obtain long smart sign indicating number modulated spread spectrum signal S respectively _LongWith short smart sign indicating number modulated spread spectrum signal S _Short:

In the present embodiment, the navigation message that generates is carried out mole and adds computing with long smart sign indicating number, short smart sign indicating number respectively:

S _long＝P _{long_code}+P _data

S _short＝P _{short_code}+P _data

Step 5: carrier modulation

The long smart sign indicating number modulated spread spectrum signal that generates, short smart sign indicating number modulated spread spectrum signal are used carrier signal S respectively _CarrierCarry out carrier modulation and obtain final modulation signal S _Signal1, S _Signal2Thereby, accomplish spread-spectrum signal frequency spectrum moving on carrier wave frequency range.

S _signal1＝S _long*S _carrier

S _signal2＝S _short*S _carrier

The computing of symbol " * " expression numerical multiplication.

In the present embodiment, carrier signal S is set _CarrierBe 71MHz, then spread-spectrum signal carried out carrier modulation:

S _signal1＝S _long*S _carrier

S _signal2＝S _short*S _carrier

Can get the navigation signal of IF Modulation.

Short smart yard emissive power that the navigation signal of modulating is required proposed by the invention and the long smart yard emissive power that the navigation signal of modulating is required are respectively like Fig. 4, shown in Figure 5.Visible by Fig. 4, Fig. 5, the required emissive power of the required emissive power of short smart sign indicating number proposed by the invention and long smart sign indicating number is identical, thereby has overcome the problem that emissive power is wasted, and has realized making full use of of emissive power.

Claims (1)

1. one kind is used for the method that satellite navigation and location system reduces signal transmission power, it is characterized in that step is following:

Step 1 generates navigation message: press navigation message design and array format, generate navigation message bit information P _Data

Step 2 generates long smart sign indicating number: the generation cycle period is T _{Long_code}Second, speed is F _{Long_code}Chip lengths is L in the MHz, cycle period _{Long_code}=T _{Long_code}* F _{Long_code}Long smart sign indicating number P _{Long_code}=X ₁+ X ₂, wherein, symbol "+" expression mole adds computing, X ₁And X ₂Represent the polynomial expression that two pseudo-random sequences generate;

Step 3 generates short smart sign indicating number: the speed of definite short smart sign indicating number is consistent with long essence sign indicating number to be F _{Long_code}MHz, the sign indicating number cycle T _{Short_code}T satisfies condition _{Short_code}＜T _{Long_code}/ 10, chip lengths is L _{Short_code}=T _{Short_code}* F _{Long_code}, its short smart sign indicating number P _{Short_code}=X ' ₁+ X ' ₂, wherein, symbol "+" expression mole adds computing, X ' ₁, X ' ₂Be respectively by X ₁, X ₂The pseudo-random sequence that generator polynomial produces is pressed L _{Short_code}Length brachymemma gained;

Step 4 band spectrum modulation: navigation message bit information is carried out band spectrum modulation with long smart sign indicating number and short smart sign indicating number respectively, obtain long smart sign indicating number modulated spread spectrum signal S respectively _LongWith short smart sign indicating number modulated spread spectrum signal S _Short:

S _long＝P _{long_code}+P _data

S _short＝P _{short_code}+P _data

Step 5 carrier modulation: adopt carrier signal S _CarrierTo the long smart sign indicating number modulated spread spectrum signal S that generates _LongWith short smart sign indicating number modulated spread spectrum signal S _ShortCarry out carrier modulation, accomplish spread-spectrum signal frequency spectrum moving on carrier wave frequency range, obtain the modulation signal of satellite navigation and location system emission:

S _signal1＝S _long*S _carrier

S _signal2＝S _short*S _carrier

The computing of symbol " * " expression numerical multiplication.

Images