CN106896381B - A kind of signal search method and apparatus - Google Patents
A kind of signal search method and apparatus Download PDFInfo
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- CN106896381B CN106896381B CN201510959252.1A CN201510959252A CN106896381B CN 106896381 B CN106896381 B CN 106896381B CN 201510959252 A CN201510959252 A CN 201510959252A CN 106896381 B CN106896381 B CN 106896381B
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S19/00—Satellite radio beacon positioning systems; Determining position, velocity or attitude using signals transmitted by such systems
- G01S19/01—Satellite radio beacon positioning systems transmitting time-stamped messages, e.g. GPS [Global Positioning System], GLONASS [Global Orbiting Navigation Satellite System] or GALILEO
- G01S19/13—Receivers
- G01S19/24—Acquisition or tracking or demodulation of signals transmitted by the system
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S19/00—Satellite radio beacon positioning systems; Determining position, velocity or attitude using signals transmitted by such systems
- G01S19/01—Satellite radio beacon positioning systems transmitting time-stamped messages, e.g. GPS [Global Positioning System], GLONASS [Global Orbiting Navigation Satellite System] or GALILEO
- G01S19/13—Receivers
- G01S19/24—Acquisition or tracking or demodulation of signals transmitted by the system
- G01S19/30—Acquisition or tracking or demodulation of signals transmitted by the system code related
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- Radar, Positioning & Navigation (AREA)
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- Computer Networks & Wireless Communication (AREA)
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- Position Fixing By Use Of Radio Waves (AREA)
Abstract
The invention discloses a kind of signal search method and apparatus.Signal search method provided in this embodiment includes: to carry out difference at least twice to input signal to be multiplied, and obtains the first differential signal；Code phase search is carried out according to the first differential signal and the second differential signal, obtain the code phase of input signal, second differential signal is to carry out what multiple difference was multiplied to the corresponding pseudo-code of input signal, and the number which is multiplied with input signal progress difference is identical；Doppler frequency shift search is carried out according to input signal, pseudo-code and code phase, exports values of Doppler frequency shift and code phase.During the present invention solves the differential type correlation method execution signal search proposed by the prior art, as it is assumed that the change rate of conditional definition Doppler frequency shift is zero, and restricted larger, the lower problem of universality for causing traditional differential type correlation method in use.
Description
Technical field
The present invention relates to navigation signal capture technique field, espespecially a kind of signal search method and apparatus.
Background technique
With Global Satellite Navigation System (Global Navigation Satellite System, referred to as are as follows: GNSS)
Development, GNSS technology plays irreplaceable important function in people's daily life, it is each to be widely used in each row
Industry, such as apply in fields such as navigation, timing and mappings.
Current GNSS mainly includes global positioning system (Global Positioning System, the abbreviation in the U.S.
Are as follows: GPS), China Beidou satellite navigation system (Bei Dou, referred to as are as follows: BD), Russia GLONASS (GLObal
NAvigation Satellite System, referred to as are as follows: GLONASS) system, and the Galilean satellite positioning system in Europe
(Galileo) system.It is carried out in the business such as positioning timing using satellite navigation system, it is necessary first to capture more visible satellites
Wireless signal, generally at least four satellites, here it is so-called three-dimensional search algorithms, pseudo-code (C/A code) including satellite,
Code phase and Doppler frequency shift.For example, GPS and BD signal, data bit modulation is in pseudo-code, therefore every 20 milliseconds
(ms) it is possible to that there are data bit jumps, and for weaker satellite-signal, to capture the pseudo-code of satellite, it is necessary to adopt
With longer correlated series, therefore it will lead to Acquisition Scheme to the sensibility of data bit random jump.In order to eliminate above-mentioned catch
It is inconvenient to obtain data bit random jump bring in mode, signal can be carried out using existing differential type correlation method at present and searched
Rope；The use premise of traditional differential type correlation method assumes that the change rate of Doppler frequency shift is zero, however, in some situations
Under, above-mentioned hypothesis is invalid, such as quickly changes mobile target such as guided missile or automobile in Acceleration of starting, i.e. object
When the acceleration of body is not zero, the change rate of Doppler frequency shift is also not zero.It is not zero in the change rate of Doppler frequency shift
In the case of, signal search work can not normally be carried out by above-mentioned traditional differential type correlation method.
In conclusion during executing signal search by the differential type correlation method that the prior art proposes, as it is assumed that
The change rate of conditional definition Doppler frequency shift is zero, and cause traditional differential type correlation method it is in use it is restricted compared with
Greatly, the lower problem of universality.
Summary of the invention
In order to solve the above-mentioned technical problems, the present invention provides a kind of signal search method and apparatus, to solve by existing
During the differential type correlation method for having technology to propose executes signal search, as it is assumed that the conditional definition change of Doppler frequency shift
Rate is zero, and restricted larger, the lower problem of universality for causing traditional differential type correlation method in use.
In a first aspect, the present invention provides a kind of signal search method, comprising:
Difference at least twice is carried out to input signal to be multiplied, and obtains the first differential signal；
Code phase search is carried out according to first differential signal and the second differential signal, obtains the code phase of input signal
Position, second differential signal is to carry out what multiple difference was multiplied to the corresponding pseudo-code of the input signal, described defeated
It is identical to enter the number that the corresponding pseudo-code of signal is multiplied with input signal progress difference；
Doppler frequency shift search, output Doppler's frequency are carried out according to the input signal, the pseudo-code and the code phase
Shifting value and the code phase.
In the first possible implementation of the first aspect, described that difference phase at least twice is carried out to input signal
Multiply, obtain the first differential signal, comprising:
Multiplying is carried out to the conjugation after the input signal and input signal delay, obtains primary input letter
Number；
Multiplying is carried out to the conjugation after an input signal and input signal delay, described in acquisition
First differential signal.
It is in the second possible implementation, described right according in the first possible implementation of first aspect
Input signal carries out difference at least twice and is multiplied, before the first differential signal of acquisition, further includes:
The input signal is converted into complex number type digital signal；
It is described that difference multiplication at least twice is carried out to input signal, obtain the first differential signal, comprising:
Difference at least twice is carried out to the complex number type digital signal converted to be multiplied, and obtains the first differential signal.
According in the first possible implementation of first aspect, in the third possible implementation, described
Before first differential signal and the second differential signal progress code phase search, further includes:
Multiplying is carried out to the delay of the pseudo-code and the pseudo-code, obtains a pseudo-code, the delay of the pseudo-code with
The delay of the input signal is identical；
Multiplying is carried out to the delay of a pseudo-code and a pseudo-code, obtains second differential signal,
The delay of pseudo-code is identical as the delay of an input signal.
It is in the fourth possible implementation, described defeated according in the third possible implementation of first aspect
The delay for entering signal is identical as the delay of an input signal；Alternatively,
The delay of the pseudo-code is identical as the delay of a pseudo-code.
Second aspect, the present invention provide a kind of signal search device, comprising:
First signal acquisition module is multiplied for carrying out difference at least twice to input signal, obtains the first differential signal；
Code phase search module, the first differential signal and second for being obtained according to first signal acquisition module are poor
Sub-signal carries out code phase search, obtains the code phase of input signal, and second differential signal is to the input signal pair
The pseudo-code answered carries out what multiple difference was multiplied, and the corresponding pseudo-code of input signal and the input signal carry out difference
The number of multiplication is identical；
Doppler frequency shift search module, it is how general for being carried out according to the input signal, the pseudo-code and the code phase
Frequency displacement search is strangled, values of Doppler frequency shift and the code phase are exported.
In the first possible implementation of the second aspect, first signal acquisition module includes:
First difference multiplying unit, for carrying out multiplication to the conjugation after the input signal and input signal delay
Operation obtains an input signal；
Second difference multiplying unit, for the conjugation after an input signal and input signal delay
Multiplying is carried out, first differential signal is obtained.
According in the first possible implementation of second aspect, in the second possible implementation, the letter
Number searcher further include: conversion module, it is poor at least twice for being carried out in first signal acquisition module to input signal
Split-phase multiplies, and before obtaining the first differential signal, the input signal is converted to complex number type digital signal；
First signal acquisition module is used to carry out input signal difference at least twice to be multiplied, and obtains the first difference letter
Number, refer to: the complex number type digital signal for converting to the conversion module carries out difference at least twice and is multiplied, and it is poor to obtain first
Sub-signal.
According in the first possible implementation of second aspect, in the third possible implementation, the letter
Number searcher further include: second signal obtains module, for being obtained in the code phase search module according to first signal
Before the first differential signal and the second differential signal that modulus block obtains carry out code phase search, to the pseudo-code and the pseudo-code
Delay carry out multiplying, obtain a pseudo-code, the delay of the pseudo-code is identical as the delay of the input signal；It is also used to
The delay of pseudo-code and a pseudo-code carries out multiplying, obtains second differential signal, the primary puppet
The delay of code is identical as the delay of an input signal.
It is in the fourth possible implementation, described defeated according in the third possible implementation of second aspect
The delay for entering signal is identical as the delay of an input signal；Alternatively,
The delay of the pseudo-code is identical as the delay of a pseudo-code.
Signal search method and apparatus provided by the invention, by carrying out code to the first differential signal and the second differential signal
Phase search, gets the code phase of input signal, then by input signal, the corresponding pseudo-code of the input signal and above-mentioned obtaining
The code phase taken carries out doppler searching, exports values of Doppler frequency shift and code phase, thus realize the capture of satellite-signal,
In, it is multiplied to obtain above-mentioned first differential signal by carrying out difference at least twice to input signal, obtain the can be made
The Doppler frequency value of one differential signal is unrelated with time change, to realize method provided by the invention not by Doppler's frequency
The influence of the change rate of shifting solves during executing signal search by the differential type correlation method that the prior art proposes, by
In the change rate that assumed condition defines Doppler frequency shift be zero, and the limitation for causing traditional differential type correlation method in use
Larger, the lower problem of universality of property.
Detailed description of the invention
Attached drawing is used to provide to further understand technical solution of the present invention, and constitutes part of specification, with this
The embodiment of application technical solution for explaining the present invention together, does not constitute the limitation to technical solution of the present invention.
Fig. 1 is a kind of entity structure schematic diagram for execution signal search that the prior art provides；
Fig. 2 is a kind of flow chart of signal search method provided in an embodiment of the present invention；
Fig. 3 is the entity structure schematic diagram for executing the signal search method that embodiment illustrated in fig. 2 provides；
Fig. 4 is the flow chart of another signal search method provided in an embodiment of the present invention；
Fig. 5 is a kind of flow chart for executing code phase search in signal search method provided in an embodiment of the present invention；
Fig. 6 is a kind of flow chart for executing Doppler frequency shift search in signal search method provided in an embodiment of the present invention；
Fig. 7 is a kind of structural schematic diagram of signal search device provided in an embodiment of the present invention；
Fig. 8 be entity apparatus shown in Fig. 3 structure basis on identify each module and unit pair in signal search device
The entity structure schematic diagram answered；
Fig. 9 is the structural schematic diagram of another signal search device provided in an embodiment of the present invention.
Specific embodiment
To make the objectives, technical solutions, and advantages of the present invention clearer, below in conjunction with attached drawing to the present invention
Embodiment be described in detail.It should be noted that in the absence of conflict, in the embodiment and embodiment in the application
Feature can mutual any combination.
Step shown in the flowchart of the accompanying drawings can be in a computer system such as a set of computer executable instructions
It executes.Also, although logical order is shown in flow charts, and it in some cases, can be to be different from herein suitable
Sequence executes shown or described step.
It is above-mentioned to have been described above four kinds of common GNSS, wherein in China and the Asian-Pacific area, especially with GPS and Beidou application
Relatively broad, and in Russia, with GPS and GLONASS using more, and Galileo system is mature far away, not can provide still just
Formula service.In above-mentioned four kinds of main GNSS, GPS, BD and Galileo are all made of CDMA (Code Division
Multiple Access, referred to as are as follows: CDMA) signaling mode, only GLONASS is using frequency division multiple access (Frequency
Division Multiple Access, referred to as are as follows: FDMA) signaling mode.Various embodiments of the present invention provide technology towards
Therefore CDMA signal although following embodiment is explained by taking the way of search of GPS signal as an example, is equally applicable to Beidou
With in Galileo system or even its thought also extends in GLONASS system.
Differential type correlation method in the prior art introduced below, the differential type correlation method are also known as delay multiplication method, such as Fig. 1
It is shown, for a kind of entity apparatus sterogram for execution signal search that the prior art provides；Input the signal of code phase search engine
Including respectively to SIF(n) and the difference multiplied value of X (n), for ease of calculation, SIF(n) complex number type number letter can be expressed as
Number.Illustrate the concept that difference is multiplied first, refers to a certain differential signal and its conjugate multiplication after being delayed, in the differential type correlation method
In, it need to be to SIF(n) difference is carried out with X (n) to be multiplied, be then specially to X (n) and its delay multiplication since X (n) is real number.It can
See, the signal of input code phase search engine includes:WithIts
In, m is to postpone in other words the time of delay using point number, and X (n) is the pseudo-code generated using C/A code generator, in satellite
In the case that signal determines, which is given value, can be simulated by C/A code generator, and needs and input
Signal SIF(n) identical delay and calculation are carried out.
It is an actually-received the signal S of certain satelliteIFIt (n) can be with table are as follows:
SIF(n)=AX (n) D (n) exp (j2 π fin) (1)
Wherein, the A in above-mentioned formula (1) indicates signal amplitude, and X (n) indicates the pseudo-code of the satellite, and D (n) indicates the satellite
Navigation message data bit, fiFor it is unknown, comprising the IF frequency including Doppler frequency shift, then SIF(n) with
Product are as follows:
In above-mentioned formula (2), since value is constant in 20ms by navigation message data bit sample point D (n), it is believed that D
(n) D (n-m) is 1, it can be deduced that the content about after equal sign, at this point, also due to m is very small, it is believed that X (n) and X (n-m)
Substantially quite, and symbol is identical, in the case, [X (n)]2It is+1, however, in some cases, [X (n)]2It may be -1,
At this point, the mode of above-mentioned search signal is then invalid.
As can be seen that although traditional differential type correlation method can solve the problem of data bit random jump is brought, but
It is which is to have supposed premise, universality is poor, is unsuitable in the application scenarios for being applied to various possible situations.Cause
This, needs to propose that one kind can be in blanket signal search method at present.
Technical solution of the present invention is described in detail below by specific embodiment, the following embodiment of the present invention
In terminal device can be navigation device, or be the intelligent terminal with navigation feature, such as smart phone, tablet computer
Or personal digital assistant (Personal Digital Assistant, referred to as are as follows: PDA) etc..The present invention provides following tool
The embodiment of body can be combined with each other, and the same or similar concept or process may be repeated no more in some embodiments.
Fig. 2 is a kind of flow chart of signal search method provided in an embodiment of the present invention.Signal provided in this embodiment is searched
In the case where Suo Fangfa is suitable for scanning for satellite-signal, this method can be executed by signal search device, which searches
Rope device realizes that the device can integrate in the processor of terminal device usually in method that hardware and software combines,
It calls and uses for processor.As shown in Fig. 2, the method for the present embodiment may include:
S110 carries out difference at least twice to input signal and is multiplied, obtains the first differential signal.
In the present embodiment, specifically to have carried out being explained for difference is multiplied twice to input signal, the present embodiment
In Doppler frequency change rate and be not zero, the change rate of Doppler frequency shift can be defined are as follows:
Wherein, the α in above formula indicates the change rate of Doppler frequency shift, fi,nIndicate moment n, it is unknown, include Doppler
IF frequency including frequency displacement, fi,0It is expressed as comprising the IF frequency including initial time Doppler frequency shift, then, input letter
It number can indicate are as follows: SIF(n)=AX (n) D (n) exp (j2 π fi,nn).The mesh that difference is multiplied at least twice is carried out in the present embodiment
Be the influence for avoiding the change rate of Doppler frequency to signal frequency value as far as possible.
Due to carrying out first difference multiplication to input signal, i.e., by SIF(n)=AX (n) D (n) exp (j2 π fi,nN) it substitutes into
It arrivesIn, an obtained input signal are as follows:
It is apparent that the differential signal S in above-mentioned (3) formuladif(n) Doppler frequency value is related with moment n, i.e., at any time
And change, illustrate to be not suitable in such a way that above-mentioned differential type correlation method in the prior art carries out signal search.The present embodiment
On the basis of first difference is multiplied, second order difference multiplication is carried out to input signal, i.e., to Sdif(n) difference multiplication is carried out, and it is upper
State carry out the multiplication of first time difference mode similarly,Above-mentioned (3) are substituted into wherein, it can
:
Can be seen that no matter whether α value is 0, S from above-mentioned (4) formuladif2(n) Doppler frequency value is one normal
Number.Since the change rate of Doppler frequency shift has changed with time very little, the i.e. acceleration (jerking movement speed) of object
Very little, so can guarantee S substantiallydif2(n) Doppler frequency value is not influenced by time change.
Again since value is constant in 20ms by navigation message data bit sample point D (n), so can be by Sdif2(n) it expresses
Formula (4) is approximately as follows:
Sdif2(n)≈A4X(n)X(n-m)X(n-p)X(n-m-p)exp(j2π2pmα) (5)
At this point it is possible to will be by the S that is obtained in above-mentioned (5) formuladif2(n) the first difference as input code phase search engine
Signal.
The present embodiment carries out the detailed process that difference is multiplied at least twice to input signal, i.e. S110 may include: to defeated
Conjugation after entering signal and input signal delay carries out multiplying, obtains an input signal；To an input signal and one
Conjugation after secondary input signal delay carries out multiplying, obtains the first differential signal.In the present embodiment, it is poor for the second time to execute
It is that split-phase multiplies as a result, i.e. secondary input signal be the first differential signal, if desired execute three times difference multiplication, then three times input letter
Number be the first differential signal.
S120 carries out code phase search according to the first differential signal and the second differential signal, obtains the code phase of input signal
Position, second differential signal are to carry out what multiple difference was multiplied to the corresponding pseudo-code of input signal, the input signal pair
The number that the pseudo-code answered is multiplied with input signal progress difference is identical.
In the present embodiment, with reference to above-mentioned (5) formula it is found that obtaining Sdif2(n) code phase can simulate input letter
The known conditions of number corresponding pseudo-code as search, it is clear that, X (n) X (n-m) X (n-p) X (n-m-p) in above-mentioned formula (5) can
With by C/A code generator simulate come, due to the standard of the known satellite before searching for signal, i.e., the pseudo-code X of the known satellite
(n), C/A code generator simulation X (n) can be first passed through, is then multiplied by carrying out the difference of same number to X (n), this implementation
Example is multiplied by executing difference twice to pseudo-code X (n), obtains the second differential signal, second differential signal specifically:
Xdif2(n)=D (n) D (n-m) (n-p) D (n-m-p).
The present embodiment can use first difference letter after two differential signals for getting input code phase search engine
Number Sdif2(n) and the second differential signal Xdif2(n) code phase search is carried out, code phase τ is obtained by specific algorithm.
It should be noted that the present embodiment is when carrying out difference to input signal and pseudo-code and being multiplied, the first of input signal
The delay that secondary difference is multiplied is identical as the delay that pseudo-code first time difference is multiplied, the delay that second of difference of input signal is multiplied
It is identical as the delay that second of difference of pseudo-code is multiplied.In addition, the conjugation of delay is no in all senses since pseudo-code is real number,
Therefore, be multiplied to the difference of pseudo-code is to carry out multiplication operation to pseudo-code and its value after being delayed.
S130 carries out Doppler frequency shift search according to input signal, pseudo-code and code phase, exports values of Doppler frequency shift and code
Phase.
The present embodiment is by known input signal SIF(n), pseudo-code X (n) and the code phase τ of above-mentioned acquisition is as Doppler's frequency
The input for moving search engine, can export values of Doppler frequency shift and code phase, that is, complete the capture of current satellite signal, Ke Yitong
The satellite-signal for crossing capture carries out accurately timing and positions, and realizes the function of search of navigation signal.
As shown in figure 3, to execute the entity structure schematic diagram for the signal search method that embodiment illustrated in fig. 2 provides.Due to
Input signal in embodiment illustrated in fig. 2 has all carried out difference twice with corresponding pseudo-code and has been multiplied, it can be seen that inputs in Fig. 3
The first differential signal and the second differential signal of code phase search engine are respectively to have carried out difference twice to input signal and pseudo-code
It being multiplied and obtains, wherein the delay value that input signal is multiplied with the first time difference of pseudo-code is identical, and the second of input signal and pseudo-code
The delay value that secondary difference is multiplied is also identical.
Signal search method provided in this embodiment, by carrying out code phase to the first differential signal and the second differential signal
Search, gets the code phase of input signal, then by input signal, the corresponding pseudo-code of the input signal and above-mentioned acquisition
Code phase carries out doppler searching, values of Doppler frequency shift and code phase is exported, to realize the capture of satellite-signal, wherein logical
Cross to input signal carry out at least twice difference be multiplied to obtain above-mentioned first differential signal, can make obtain the first difference
The Doppler frequency value of signal is unrelated with time change, to realize method provided in this embodiment not by Doppler frequency shift
The influence of change rate solves during executing signal search by the differential type correlation method that the prior art proposes, due to vacation
If the change rate of conditional definition Doppler frequency shift is zero, and cause traditional differential type correlation method it is in use it is restricted compared with
Greatly, the lower problem of universality.
Further, signal search method provided in this embodiment first carries out linear search to two differential signals and finds
The code phase of input signal carries out another dimension further according to determining code phase, input signal and the corresponding pseudo-code of input signal and searches
Rope finds the values of Doppler frequency shift of input signal, so as to complete the code phase and values of Doppler frequency shift to current satellite signal
Search, namely the capture of current satellite signal is completed, two linear searches are instead of the two-dimensional search in original scheme, significantly
Reduce searching times, search time and complexity.
On the basis of above-mentioned embodiment illustrated in fig. 2, it can be seen that from above-mentioned (4) formula through selection m appropriate and p value,
Such as setting m=p, i.e. the be multiplied delay that is multiplied with second order difference of first difference is identical, can achieve reduction operation complexity
Effect because as m=p, X (n-m) X (n-p)=1 can largely reduce the complexity of operation.
It should be noted that above-mentioned embodiment illustrated in fig. 2 is specifically given by executing for difference is multiplied twice to input signal
To show, that is, the condition that the change rate of Doppler frequency shift in traditional differential type correlation method is 0 is removed, that is, removes input signal
The condition that acceleration is 0；Correspondingly, it is 0 that the assumed condition in Fig. 2, which is the acceleration of input signal, if being not intended to set defeated
The acceleration for entering signal is 0, and the difference that can also try again to input signal is multiplied, and then adding for input signal is accelerated at this time
The influence of degree is also taken into account.But the acceleration of input signal is not 0 almost unreliable existing, therefore, to input
Signal, which carries out difference multiplication twice, has had general applicability.
Optionally, Fig. 4 is the flow chart of another signal search method provided in an embodiment of the present invention.In view of the present invention
Operation mode of the embodiment when carrying out code phase search to the first differential signal and the second differential signal, usually plural fortune
It calculates, common input signal is plural form, convenient and fast in order to reach subsequent arithmetic if the input signal is non-complex form
Input signal just can be converted to complex number type digital signal, i.e., before S110, also wrapped by effect before carrying out difference multiplication
It includes: S100 and input signal is converted into complex number type digital signal；Correspondingly, S110 could alternatively be: to the complex number type converted
Digital signal carries out difference at least twice and is multiplied, and obtains the first differential signal.The present embodiment obtains the mode of the first differential signal
It is identical as embodiment illustrated in fig. 2, therefore details are not described herein.
It should be noted that in the above embodiments, first got that be multiplied by the difference to input signal is defeated
Enter the expression formula (5) of signal, wherein X (n) X (n-m) X (n-p) X (n-m-p) in formula (5) can pass through C/A code generator mould
It draws up and, the process of simulation, which is similarly, executes difference multiplication, since X (n) can be generated directly by C/A code generator, to the X
(n) it executes with input signal same number and the difference of identical delay is multiplied, X (n) X (n-m) X (n-p) X (n- can be got
m-p).Specifically, the present embodiment is before S110, further includes: S101 carries out multiplying to the delay of pseudo-code and pseudo-code, obtains
A pseudo-code is taken, the delay of the pseudo-code and the delay of input signal are identical；S102, to the delay of a pseudo-code and a pseudo-code into
Row multiplying, obtains the second differential signal, and the delay of a pseudo-code is identical as the delay of an input signal.
It should be noted that the present embodiment does not limit the execution step of S101~S102 Yu S100 and S110, that is, obtain the
One differential signal and the second differential signal of acquisition execute respectively, as long as guaranteeing to get the first differential signal before S120
With the second differential signal, Fig. 4 is shown so that S101~S102 is executed after S110 as an example.
Code phase search algorithm in the various embodiments described above can be using common related to Doppler frequency shift searching algorithm
It operates, take absolute value, maximizing and finding out the corresponding code phase values of maximum value and values of Doppler frequency shift, can also use
Other parallel algorithms, also can be there are many implementation method.Below by way of some specific examples illustrate carry out code phase search and
Carry out the concrete mode of values of Doppler frequency shift search.
For example, Fig. 5 is a kind of stream for executing code phase search in signal search method provided in an embodiment of the present invention
Method shown in Cheng Tu, Fig. 5 includes:
S210 selects one section of first differential signal Sdif2(n) data.
S220 selects a code phase values τ.
S230, by the second differential signal Xdif2(n) be delayed a code phase values τ, and with the first differential signal Sdif2(n)
Sample point is corresponding to be multiplied, and then multiplied result adds up, takes absolute value to accumulation result.
S220~S230 is repeated, when repeating, is selected and code phase values different before, all yards of phases of traversal
Place value.
S240 finds the maximum value of the corresponding accumulation result absolute value of all code phase values, the corresponding code phase of the maximum value
Place value is the code phase searched for and obtained.
Again for example, Fig. 6 searches for execution Doppler frequency shift a kind of in signal search method provided in an embodiment of the present invention
The flow chart of rope, method shown in Fig. 6 include:
S310 selects one section of input signal SIF(n) data, take its real part, also can use its imaginary part, the present embodiment is with real part
For be explained；And according to the code phase obtained before, the corresponding pseudo-code X (n) of input signal is postponed in advance, is prolonged
Slow pseudo-code Xτ(n)。
S320, selecting one includes values of Doppler frequency shift fdIF frequency fi。
S330 generates local signal X according to the IF frequency value of selectionτ(n)exp(j2πfiN), sample-by-sample point and input
Signal SIF(n) real part sequence is multiplied, and adds up；Then, it takes absolute value to accumulation result, namely to plural modulus.
S220~S230 is repeated, when repeating, selects intermediate frequency corresponding from values of Doppler frequency shift different before
Frequency traverses the corresponding IF frequency of all values of Doppler frequency shift.
S340, finds the maximum value of the corresponding accumulation result absolute value of all values of Doppler frequency shift, and the maximum value is corresponding
Values of Doppler frequency shift is the values of Doppler frequency shift searched and obtained.
Fig. 7 is a kind of structural schematic diagram of signal search device provided in an embodiment of the present invention.Letter provided in this embodiment
Number searcher is suitable in the case where scanning for satellite-signal, the side which is usually combined with hardware and software
Method realizes that the device can integrate in the processor of terminal device, calls and uses for processor.As shown in fig. 7, this implementation
The signal search deployment device of example specifically includes: the first signal acquisition module 11, code phase search module 12 and Doppler frequency shift
Search module 13.
Wherein, the first signal acquisition module 11 is multiplied for carrying out difference at least twice to input signal, it is poor to obtain first
Sub-signal.
In the concrete realization, the first signal acquisition module 11 may include: the first difference multiplying unit 14 to the present embodiment, use
In carrying out multiplying to the conjugation after input signal and input signal delay, an input signal is obtained；Second difference is multiplied
Unit 15 obtains the first difference for carrying out multiplying to the conjugation after an input signal and an input signal delay
Signal.With reference to entity apparatus shown in Fig. 3, the first difference multiplying unit 14 in the present embodiment can be by believing input in Fig. 3
Number carry out difference multiplication delayer, conjugation converter and multiplier composition, the second difference multiplying unit 15 can be by right in Fig. 3
Input signal carries out the delayer, conjugation converter and multiplier composition of difference multiplication；As shown in figure 8, being shown in Fig. 3
Each module and the corresponding entity structure schematic diagram of unit in signal search device are identified in the structure basis of entity apparatus.
It should be noted that the present embodiment has equally to carry out being shown for difference is multiplied twice to input signal
Body operation mode is identical as above-mentioned embodiment illustrated in fig. 2, and each formula in calculating process can also arrive formula with reference to above-mentioned formula (3)
(5), therefore details are not described herein.
Code phase search module 12, the first differential signal and second for being obtained according to the first signal acquisition module 11 are poor
Sub-signal carries out code phase search, obtains the code phase of input signal, which is to the corresponding puppet of input signal
Code carries out what multiple difference was multiplied, and the corresponding pseudo-code of the input signal carries out the number phase that difference is multiplied with input signal
Together.
It again may be by the corresponding pseudo-code X (n) of C/A code generator analog input signal in the present embodiment, then pass through
It is multiplied to X (n) difference for carrying out same number, obtains the second differential signal, the expression formula of second differential signal equally can be with
Are as follows: Xdif2(n)=D (n) D (n-m) (n-p) D (n-m-p).
It should be noted that the present embodiment is when carrying out difference to input signal and pseudo-code and being multiplied, the first of input signal
The delay that secondary difference is multiplied is identical as the delay that pseudo-code first time difference is multiplied, the delay that second of difference of input signal is multiplied
It is identical as the delay that second of difference of pseudo-code is multiplied.In addition, the conjugation of delay is no in all senses since pseudo-code is real number,
Therefore, be multiplied to the difference of pseudo-code is to carry out multiplication operation to pseudo-code and its value after being delayed.
Doppler frequency shift search module 13, the code for being obtained according to input signal, pseudo-code and code phase search module 12
Phase carries out Doppler frequency shift search, exports values of Doppler frequency shift and code phase.
Signal search device provided in an embodiment of the present invention is used to execute the signal that embodiment illustrated in fig. 2 of the present invention provides and searches
Suo Fangfa has corresponding functional module, and it is similar that the realization principle and technical effect are similar, and details are not described herein again.
Similarly, it on the basis of above-mentioned embodiment illustrated in fig. 7, can be seen that from above-mentioned (4) formula through selection appropriate
The delay that m and p value, such as setting m=p, i.e. first difference multiplication are multiplied with second order difference is identical, and it is multiple to can achieve reduction operation
The effect of miscellaneous degree, because as m=p, X (n-m) X (n-p)=1 can largely reduce the complexity of operation.
Optionally, Fig. 9 is the structural schematic diagram of another signal search device provided in an embodiment of the present invention.In above-mentioned figure
In the structure basis of 7 shown devices, further includes: conversion module 16, for the first signal acquisition module 11 to input signal into
Difference is multiplied row at least twice, and before obtaining the first differential signal, input signal is converted to complex number type digital signal；Accordingly
Ground, the first signal acquisition module 11 are used to carry out input signal difference at least twice to be multiplied, obtain the first differential signal, be
Refer to: the complex number type digital signal for converting to conversion module 16 carries out difference at least twice and is multiplied, and obtains the first differential signal.
The mode that the present embodiment obtains the first differential signal is identical as the various embodiments described above, therefore details are not described herein.
It should be noted that in the above embodiments, first got that be multiplied by the difference to input signal is defeated
Enter the expression formula (5) of signal, wherein X (n) X (n-m) X (n-p) X (n-m-p) in formula (5) can pass through C/A code generator mould
It draws up and, the process of simulation, which is similarly, executes difference multiplication, since X (n) can be generated directly by C/A code generator, to the X
(n) it executes with input signal same number and the difference of identical delay is multiplied, X (n) X (n-m) X (n-p) X (n- can be got
m-p).Specifically, device provided in this embodiment further include: second signal obtains module 17, in code phase search module
It is right before 12 the first differential signals obtained according to the first signal acquisition module 11 and the second differential signal carry out code phase search
The delay of pseudo-code and pseudo-code carries out multiplying, obtains a pseudo-code, the delay of the pseudo-code and the delay of input signal are identical；Also
Delay for a pseudo-code and a pseudo-code carries out multiplying, obtains the second differential signal, the delay of a pseudo-code and one
The delay of secondary input signal is identical.Second signal, which is identified, in same entity structure shown in Fig. 8 obtains the corresponding reality of module 17
Body structure.
Signal search device provided in an embodiment of the present invention is used to execute the signal that embodiment illustrated in fig. 4 of the present invention provides and searches
Suo Fangfa has corresponding functional module, and it is similar that the realization principle and technical effect are similar, and details are not described herein again.
It should be noted that the code phase search module 12 in the present embodiment can be the code in entity structure shown in Fig. 8
Phase search engine, Doppler frequency shift search module 13 can be the Doppler frequency shift search engine in entity structure shown in Fig. 8, execute
Code phase search and the concrete mode of execution Doppler frequency shift search are in the above-described embodiments it is stated that therefore no longer superfluous herein
It states.
Although disclosed herein embodiment it is as above, the content only for ease of understanding the present invention and use
Embodiment is not intended to limit the invention.Technical staff in any fields of the present invention is taken off not departing from the present invention
Under the premise of the spirit and scope of dew, any modification and variation, but the present invention can be carried out in the form and details of implementation
Scope of patent protection, still should be subject to the scope of the claims as defined in the appended claims.
Claims (8)
1. a kind of signal search method characterized by comprising
Difference at least twice is carried out to input signal to be multiplied, and obtains the first differential signal；
Code phase search is carried out according to first differential signal and the second differential signal, obtains the code phase of input signal, institute
Stating the second differential signal is to carry out what multiple difference was multiplied to the corresponding pseudo-code of the input signal, the input signal
The number that corresponding pseudo-code is multiplied with input signal progress difference is identical；
Doppler frequency shift search is carried out according to the input signal, the pseudo-code and the code phase, exports values of Doppler frequency shift
With the code phase；
Wherein, described that difference multiplication at least twice is carried out to input signal, obtain the first differential signal, comprising:
Multiplying is carried out to the conjugation after the input signal and input signal delay, obtains an input signal；
Multiplying is carried out to the conjugation after an input signal and input signal delay, obtains described first
Differential signal.
2. signal search method according to claim 1, which is characterized in that described poor at least twice to input signal progress
Split-phase multiplies, before the first differential signal of acquisition, further includes:
The input signal is converted into complex number type digital signal；
It is described that difference multiplication at least twice is carried out to input signal, obtain the first differential signal, comprising:
Difference at least twice is carried out to the complex number type digital signal converted to be multiplied, and obtains the first differential signal.
3. signal search method according to claim 1, which is characterized in that described according to first differential signal and
Two differential signals carry out before code phase search, further includes:
Multiplying is carried out to the delay of the pseudo-code and the pseudo-code, obtains a pseudo-code, the delay of the pseudo-code with it is described
The delay of input signal is identical；
Multiplying is carried out to the delay of a pseudo-code and a pseudo-code, obtains second differential signal, it is described
The delay of pseudo-code is identical as the delay of an input signal.
4. signal search method according to claim 3, which is characterized in that the delay of the input signal and described primary
The delay of input signal is identical；Alternatively,
The delay of the pseudo-code is identical as the delay of a pseudo-code.
5. a kind of signal search device characterized by comprising
First signal acquisition module is multiplied for carrying out difference at least twice to input signal, obtains the first differential signal；
Code phase search module, the first differential signal and the second difference letter for being obtained according to first signal acquisition module
Number code phase search is carried out, obtains the code phase of input signal, second differential signal is corresponding to the input signal
Pseudo-code carries out what multiple difference was multiplied, and the corresponding pseudo-code of the input signal carries out difference with the input signal and is multiplied
Number it is identical；
Doppler frequency shift search module, for carrying out Doppler's frequency according to the input signal, the pseudo-code and the code phase
Search is moved, values of Doppler frequency shift and the code phase are exported；
Wherein, first signal acquisition module includes:
First difference multiplying unit, for carrying out multiplication fortune to the conjugation after the input signal and input signal delay
It calculates, obtains an input signal；
Second difference multiplying unit, for being carried out to the conjugation after an input signal and input signal delay
Multiplying obtains first differential signal.
6. signal search device according to claim 5, which is characterized in that the signal search device further include: conversion
Module is multiplied for carrying out difference at least twice to input signal in first signal acquisition module, obtains the first difference letter
Before number, the input signal is converted into complex number type digital signal；
First signal acquisition module is used to carry out input signal difference at least twice to be multiplied, and obtains the first differential signal,
Refer to: the complex number type digital signal for converting to the conversion module carries out difference at least twice and is multiplied, and obtains the first difference
Signal.
7. signal search device according to claim 5, which is characterized in that the signal search device further include: second
Signal acquisition module, for being believed in the code phase search module according to the first difference that first signal acquisition module obtains
Number and before the second differential signal carries out code phase search, multiplying is carried out to the delay of the pseudo-code and the pseudo-code, is obtained
A pseudo-code is taken, the delay of the pseudo-code is identical as the delay of the input signal；It is also used to a pseudo-code and described one
The delay of secondary pseudo-code carries out multiplying, obtains second differential signal, the delay of a pseudo-code and described once defeated
The delay for entering signal is identical.
8. signal search device according to claim 7, which is characterized in that the delay of the input signal and described primary
The delay of input signal is identical；Alternatively,
The delay of the pseudo-code is identical as the delay of a pseudo-code.
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