CN112180407A - Method for eliminating mutual interference of strong and weak signals - Google Patents

Method for eliminating mutual interference of strong and weak signals Download PDF

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CN112180407A
CN112180407A CN202010959169.5A CN202010959169A CN112180407A CN 112180407 A CN112180407 A CN 112180407A CN 202010959169 A CN202010959169 A CN 202010959169A CN 112180407 A CN112180407 A CN 112180407A
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signal
positioning
interference
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code
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张遂征
秦虎
范成柏
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Beijing Hongdexin Zhiyuan Information Technology Co ltd
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Beijing Hongdexin Zhiyuan Information Technology Co ltd
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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
    • G01S19/21—Interference related issues ; Issues related to cross-correlation, spoofing or other methods of denial of service
    • 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
    • G01S19/23—Testing, monitoring, correcting or calibrating of receiver elements
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
    • H04B1/06—Receivers
    • H04B1/10—Means associated with receiver for limiting or suppressing noise or interference

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Abstract

The invention discloses a method for eliminating mutual interference of strong and weak signals, which is particularly suitable for eliminating the interference of the strong signal to the weak signal when the strength difference of each signal in a ground positioning system (comprising an indoor and outdoor positioning system) of a BDS (Beidou satellite navigation system) and GPS (global positioning system) like positioning (navigation) signal generation and broadcasting system is large so as to realize the accurate tracking of each signal (comprising the weak signal). The method comprises the following steps: preprocessing of mutual interference calculation, calculation and elimination of mutual interference under the condition of superposition of a plurality of positioning (navigation) signals and the like. The invention solves the problem of tracking each signal under the condition of strong and weak signal superposition in a ground positioning system, and improves the tracking precision and sensitivity of weak signals.

Description

Method for eliminating mutual interference of strong and weak signals
Technical Field
The invention discloses a method for eliminating mutual interference of strong and weak signals, in particular to a method for eliminating mutual interference among signals when demodulating the signals under the condition of overlapping a plurality of positioning (navigation) signals in a ground positioning system (comprising an indoor and outdoor positioning system), and particularly relates to a signal demodulation and tracking method in the field of wireless indoor and outdoor positioning (navigation) and under the condition of overlapping a plurality of strong and weak signals.
Background
In the field of wireless positioning (navigation), a positioning (navigation) message is subjected to radio broadcasting after being modulated by a CA (orthogonal pseudo-random code, gold code and ranging code) and a carrier, and after a receiver receives, demodulates, tracks and ranges (a pseudo range from the receiver to a signal source or a pseudo range difference from the receiver to two signal sources), the position of the receiver can be calculated by the following formula:
Figure BDA0002679814490000011
where ρ isi(i 1,2,3,4) is the pseudorange measurement between the receiver and the signal source i, tuIs the difference between the receiver clock and the signal source clock, (x)i,yi,zi) I is the coordinate of signal source i, (x) is 1,2,3,4u,yu,zu) Are the receiver coordinates. The accuracy of the distance measurement depends on the tracking precision of the receiver to the positioning (navigation) signal, and the higher the tracking precision is, the more accurate the distance measurement value is, so that the calculated position precision of the receiver is higher.
In a satellite positioning (navigation) system, because the distances from satellites to a ground receiver are not greatly different (the distance ratio is close to 1), the strength of positioning (navigation) signals broadcast by each satellite received by the receiver is also not greatly different, so that the difference of the strength of each signal can be not considered, namely the interference of strong signals to weak signals can be ignored.
In a terrestrial positioning system, as shown in fig. 1, as the receiver is located at different positions (it can be assumed that the transmission power of each signal source is substantially equal), the following characteristics are exhibited:
(1) the receivers are at widely differing distances from the sources, which may be several to more than a hundred times the distance from the closer source (e.g., the ratio of 2-a to 2-D for receiver 2 and the ratio of 3-B to 3-C for receiver 3 in fig. 1). Correspondingly, according to the signal propagation law, the receiver receives a signal source with a relatively high intensity and a signal source with a relatively low intensity, and the ratio of the intensity to the intensity is from several times to tens of thousands of times.
(2) The receiver is located at different positions, and the distance relationship between the receiver and each signal source changes along with the distance relationship, that is, the strength relationship between the signal received by the receiver and each signal source changes along with the distance relationship, so that the strength relationship between the signals received by the receiver changes continuously.
Depending on the codes used for the modulation of the positioning (navigation) messages CA, the cross-correlation value between the signal sources CA is usually less than 2% (compared to the autocorrelation value after CA code alignment). Therefore, in a terrestrial positioning system, when the strength of each signal received by the receiver is not greatly different, the interference between the signals can be ignored, but when the strength of each signal received by the receiver is greatly different, so that the interference of the strong signal to the weak signal reaches or exceeds the same order of magnitude of the weak signal, the interference between the signals can not be ignored (which is commonly called the suppression of the strong signal to the weak signal, thereby reducing the signal-to-noise ratio of the signal to an unacceptable degree).
BRIEF SUMMARY OF THE PRESENT DISCLOSURE
The purpose of the present disclosure is to provide a method for eliminating mutual interference between strong and weak signals, including:
performing early, instantaneous and late CA code stripping and carrier stripping of tracking signal h | ((1, 2.. multidot.M)) on the received signal
Figure BDA0002679814490000021
Integrating for N time length to obtain leading, real-time and lagging IQ integral values
Figure BDA0002679814490000022
Figure BDA0002679814490000023
And carrying out CA (rank order) code stripping and carrier stripping on a positioning signal k (1, 2,.. multidot.M;. noteh) of the tracking signal h | ((1, 2.. multidot.M)) on a receiving signal
Figure BDA0002679814490000024
Integrating the positioning signals with the time length of N to obtain the real-time IQ integral value of each positioning signal k (1, 2, M ≠ h)
Figure BDA0002679814490000031
Wherein the positioning signal k (═ 1, 2., M; ≠ h) is generated for the tracking signal h | (-1, 2., M)Generating interference, the
Figure BDA0002679814490000032
And
Figure BDA0002679814490000033
the integral starting sampling time is the same as the integral starting sampling time of the tracking signal h (═ 1, 2., M), and the integral duration is the same;
from duplicate CA code sequences generated during tracking of each positioning signal
Figure BDA0002679814490000034
And copying the carrier phase sequence
Figure BDA0002679814490000035
Obtaining interference to tracking signal h
Figure BDA0002679814490000036
And
Figure BDA0002679814490000037
y is expressed as a pre-processing IQ value;
interference to the tracking signal h
Figure BDA0002679814490000038
And
Figure BDA0002679814490000039
integrating the time length N to obtain an interference preprocessing IQ value of each positioning signal k (═ 1, 2., M, ≠ h) on the tracking signal h:
Figure BDA00026798144900000310
Figure BDA00026798144900000311
by using the said
Figure BDA00026798144900000312
Instead of being actual
Figure BDA00026798144900000313
The signal amplitude of each positioning signal k (═ 1, 2.., M ≠ h) is calculated
Figure BDA00026798144900000314
And text data code
Figure BDA00026798144900000315
According to the signal amplitude of each positioning signal k (═ 1, 2.., M ≠ h)
Figure BDA00026798144900000316
And text data code
Figure BDA00026798144900000317
The interference IQ component of each positioning signal k (═ 1, 2.., M ≠ h) on tracking signal h is calculated
Figure BDA00026798144900000318
Figure BDA00026798144900000319
According to the interference IQ component of each positioning signal k (1, 2.., M ≠ h) to the tracking signal h
Figure BDA00026798144900000320
Figure BDA00026798144900000321
And the IQ integral value
Figure BDA00026798144900000322
Figure BDA00026798144900000323
Calculated to obtain signals without mutual interference of positioning signals
Figure BDA00026798144900000324
In one example, the method of canceling interference further comprises:
using mutual interference of said non-location signals
Figure BDA00026798144900000325
Code phase correction, carrier frequency and phase correction, and data bit decoding, TOA or TDOA measurements are performed.
In one example, the duplicate CA code sequence generated by each positioning signal tracking process
Figure BDA00026798144900000326
And copying the carrier phase sequence
Figure BDA00026798144900000327
Obtaining interference to tracking signal h
Figure BDA00026798144900000328
And
Figure BDA00026798144900000329
the method comprises the following steps:
is calculated according to the following formula
Figure BDA0002679814490000041
Wherein
Figure BDA0002679814490000042
To locate the duplicate CA code spreading sequence of signal h,
Figure BDA0002679814490000043
is the phase of the replica carrier of the positioning signal h at the time instant of sample n.
In one example, the utilizing is of
Figure BDA0002679814490000044
Instead of being actual
Figure BDA0002679814490000045
The signal amplitude of each positioning signal k (═ 1, 2.., M ≠ h) is calculated
Figure BDA0002679814490000046
And text data code
Figure BDA0002679814490000047
The method comprises the following steps:
is calculated according to the following formula
Figure BDA0002679814490000048
In one example, the signal amplitude is determined from the signal amplitude of each positioning signal k (═ 1, 2., M ≠ h)
Figure BDA0002679814490000049
And text data code
Figure BDA00026798144900000410
The interference IQ component of each positioning signal k (═ 1, 2.., M ≠ h) on tracking signal h is calculated
Figure BDA00026798144900000411
Figure BDA00026798144900000412
The method comprises the following steps:
is calculated according to the following formula
Figure BDA00026798144900000413
In one example, an interfering IQ component of the tracking signal h is determined from the respective positioning signal k (═ 1, 2., M ≠ h)
Figure BDA00026798144900000414
Calculated to obtain signals without mutual interference of positioning signals
Figure BDA00026798144900000415
The method comprises the following steps:
is calculated according to the following formula
Figure BDA00026798144900000416
Compared with the prior art, the method has the advantages that the problem of tracking each signal under the condition of strong and weak signal superposition in the ground positioning system is solved, and the tracking precision and sensitivity of weak signals are improved.
Drawings
Fig. 1 is a schematic diagram of a relationship between positioning signal source deployment and receiver position of a terrestrial positioning system, and shows that, due to different receiver positions, distances between a receiver and a positioning signal source are greatly different (from close to nearly one hundred times), so that the strength difference of each positioning signal received by the receiver is large, and mutual interference between the positioning signals cannot be ignored, and particularly, interference of a strong signal on a weak signal cannot be ignored.
Fig. 2 is a schematic diagram of a principle of calculating and eliminating mutual interference between positioning signals, where a real-line part is a processing module of a positioning signal h, and a dotted-line part is a part of a processing module of a positioning signal k, and specific implementation steps describe a calculation relationship between sub-modules of the positioning signal h processing module and the positioning signal k processing module when tracking the signal h in the schematic diagram.
Detailed Description
To make the objects, technical solutions and advantages of the embodiments of the present disclosure clearer, the technical solutions in the embodiments of the present disclosure will be clearly and completely described below with reference to the drawings in the embodiments of the present disclosure. Embodiments of the invention are operational with numerous other general purpose or special purpose computing system environments or configurations, and with numerous other electronic devices, such as terminal devices, computer systems, servers, etc.
Receiving signal representation
Assuming that the signal is constant in strength (or varies as little as can be considered constant) over the coherent integration period (1 to n < ═ 20 CA code lengths, i.e., the coherent integration period is typically less than 100 milliseconds), a single received signal without considering noise (assumed to be white noise, which can be cancelled by coherent integration) can be represented as:
Figure BDA0002679814490000051
wherein the subscript i denotes the received signal; a. theiIs the received signal amplitude; ci(t) is a CA code modulated in the received signal message; di(t) is a received signal text data code;
Figure BDA0002679814490000052
modulating a carrier wave for a received signal text (the receiving time is carried out through down-conversion, and only sine modulation or cosine modulation can be carried out, and the derivation process of the following formula is similar); j is an imaginary unit; omegaiFor receiving the angular frequency of the signal, and the carrier frequency f of the received signaliHas a relationship of ωi＝2πfi；
Figure BDA0002679814490000053
The initial phase (radian) of the received signal.
The received single signal is represented as I and Q paths:
si(t)＝ii(t)+jqi(t)
then:
Figure BDA0002679814490000061
the positioning (navigation) signal broadcast by the multiple positioning signal sources received by the receiver is a positioning signal obtained by superimposing the multiple positioning signals, and the received signal at this time may be represented as:
Figure BDA0002679814490000062
wherein M is the number of received positioning signals (navigation signals, positioning signal sources); the superscript (k) denotes the kth positioning signal received. Similarly, the I and Q paths of the received multiple superimposed positioning signals can be represented as:
Figure BDA0002679814490000063
second, receiving signal sampling sequence
The sequence of samples for a single signal by the receiver can be expressed as:
Figure BDA0002679814490000064
where n denotes the sampled value of the corresponding parameter at the nth time instant,
Figure BDA0002679814490000065
the samples for the I and Q paths may be expressed as:
si(n)＝ii(n)+jqi(n)
in the above formula ii(n) and qi(n) may be represented as:
Figure BDA0002679814490000066
the sequence of samples of the receiver for the received plurality of superimposed positioning signals may be represented as:
Figure BDA0002679814490000067
likewise, the sample sequences for the I and Q ways can be expressed as:
Figure BDA0002679814490000071
triple, coherent integration
Carrying out carrier stripping and CA code stripping on a single sampled received signal to obtain an i (n) path and a q (n) path of the received signal:
Figure BDA0002679814490000072
wherein C iso(n) is a spreading sequence of a replica CA code, which should be identical to the received CA code sequence, based on which Co(n) takes the value of +1 or-1; in the formula
Figure BDA0002679814490000073
In order to replicate a sequence of carriers,
Figure BDA0002679814490000074
to replicate the phase of the carrier at sample time n. After carrier stripping and CA code stripping, obtaining a positioning message and signal strength which have a real part of i (n) path and mainly represent; the imaginary part is q (n) paths and mainly represents carrier tracking error:
Figure BDA0002679814490000075
if the receiver tracks the code phase of the signal without error, i.e. the received CA code is perfectly aligned with the replica CA code, i.e. Co(n)＝Ci(n) ± 1, the receiver tracks the frequency and phase of the signal without error, i.e.
Figure BDA0002679814490000076
Figure BDA0002679814490000077
Then:
Figure BDA0002679814490000078
and (3) integrating I (N) and Q (N) for the time length N to obtain I path and Q path integrated values:
Figure BDA0002679814490000079
by taking the spreading sequences C of the advance (E), prompt (P) and retard (L) respectively for the duplicated CA codesoE(n)、CoP(n) and CoL(n) CA code stripping, carrier stripping and integrating to obtain leading, instantaneous and lagging IQ values, respectively:
Figure BDA0002679814490000081
Figure BDA0002679814490000082
Figure BDA0002679814490000083
the values obtained by the integration can demodulate a positioning message, code phase discrimination and carrier phase discrimination so as to obtain a data bit value, a code phase error and a carrier phase error of the positioning message, and then the carrier frequency (corresponding to a duplicated carrier) and the code phase (including a code rate and a corresponding duplicated CA code) of a tracking signal are corrected according to the code phase error and the carrier phase error and are used for tracking the subsequent receiving signal.
Four, multiple location signal tracking
The same as the received signal processing method of a single positioning signal, the received signal sampling under the condition of superposing a plurality of positioning signals is carried out, when the positioning signal h is tracked, the CA code (copy CA code) and the tracking carrier (copy carrier) of the h positioning signal are adopted to carry out CA code stripping and carrier stripping:
Figure BDA0002679814490000084
wherein
Figure BDA0002679814490000085
To locate the duplicate CA code spreading sequence of signal h,
Figure BDA0002679814490000086
to locate the replica carrier sequence of the signal h,
Figure BDA0002679814490000087
is the phase of the replica carrier of the positioning signal h at the time instant of sample n. After stripping carrier and CA code, obtaining I path I of positioning signal h(h)(n) and Q-path Q(h)(n)：
Figure BDA0002679814490000088
To i(h)(n) and q(h)(N) integrating the duration N to obtain the integral values of the I path and the Q path of the positioning signal h:
Figure BDA0002679814490000091
when k ≠ h, since CA code sequence
Figure BDA0002679814490000092
And
Figure BDA0002679814490000093
orthogonal, i.e.:
Figure BDA0002679814490000094
therefore, there are (after normalization processing):
Figure BDA0002679814490000095
further (when the receiver receives positioning signal strengths, i.e., amplitudes, that do not differ significantly):
Figure BDA0002679814490000096
by taking the spreading sequences of the advance (E), prompt (P) and lag (L) respectively for the duplicated CA codes of the positioning signal h
Figure BDA0002679814490000097
And
Figure BDA0002679814490000098
CA code stripping, carrier stripping and integration are performed to obtain leading, instantaneous and lagging IQ values, respectively:
Figure BDA0002679814490000099
by utilizing the IQ values, the data bit value of the positioning message and the phase discrimination can be demodulated to obtain a code phase error and a carrier phase error, so that the carrier frequency and the code phase of the positioning signal h are corrected and the corrected positioning signal h is used for accurately tracking and processing the subsequently received positioning signal h.
Finally, the receiver uses all M code phases of the tracked positioning signals and the demodulated positioning messages to measure the distance between the receiver and the source of the positioning signals (pseudo range and TOA) or the distance difference between the receiver and two positioning signal sources (pseudo range difference and TDOA), and then uses the TOA or TDOA measurement result to calculate the position coordinate (x) of the receiveru,yu,zu)。
Since TDOA processed by terrestrial positioning system (including indoor and outdoor positioning) receivers is mostly only in the range of several kilometers, the following implementation steps do not take into account the fact that the difference in code phase of each signal within the integration time duration N results in data bit values
Figure BDA00026798144900000910
Difference (i.e. before and after data bit transition point)
Figure BDA00026798144900000911
True) pair calculation
Figure BDA00026798144900000912
And
Figure BDA0002679814490000101
and cause a calculation
Figure BDA0002679814490000102
And
Figure BDA0002679814490000103
Figure BDA0002679814490000104
the resulting error.
In practice, there is no effect on the calculation of the data when the data bit does not jump, and there is an effect when the data bit jumps. Because now the signal k is located within the CA period of the tracking signal h
Figure BDA0002679814490000105
After the jump occurs
Figure BDA0002679814490000106
And
Figure BDA0002679814490000107
should be reversed, i.e. after a data bit transition
Figure BDA0002679814490000108
Figure BDA0002679814490000109
The integral accumulated strain is reduced.
In addition, in order to improve the receiving sensitivity of the positioning signals, the ground positioning systems (including indoor and outdoor positioning systems) like the BDS (Beidou satellite navigation system) and the GPS (global positioning system) can continuously broadcast each data bit of the positioning telegraph text for multiple times (the number of DBS and the number of GPS are 20), and the possible position of data bit jump can be predicted in the tracking process. So that it is mostly intact
Figure BDA00026798144900001010
And
Figure BDA00026798144900001011
and
Figure BDA00026798144900001012
and
Figure BDA00026798144900001013
the large overlapping part and the part after neglecting the jump can be adopted before and after the data bit jump point for approximation.
The overall logic framework of the computing operation method for eliminating the mutual interference among the signals is as follows:
IQ value of each positioning signal tracked and calculated by the positioning signal
Figure BDA00026798144900001014
Figure BDA00026798144900001015
The mutual interference between the signals is actually included, and the superscript is changed to (+ h), that is, the IQ value is recorded as
Figure BDA00026798144900001016
Of locating signal h at sampling instant n
Figure BDA00026798144900001017
And
Figure BDA00026798144900001018
comprises the following steps:
Figure BDA00026798144900001019
the above formula is divided into two parts: the first part is that the received signal h is processed with CA stripping and carrier stripping by its own copied CA code and copied carrier to obtain i needed for tracing the actual demand(h)(n) and q(h)(n) is:
Figure BDA00026798144900001020
this part i(h)(n) and q(h)(n) the relation between the reception and processing of the tracking signal h only, expressed entirely in terms of the received signalAmplitude of h
Figure BDA00026798144900001021
Value of textual data bit
Figure BDA00026798144900001022
And its tracking error.
The second part adopts the copy CA of the received signal h and the copy carrier wave to carry out CA stripping and carrier stripping for the non-h part of the received signal, and replaces the corresponding non-h receiving CA and receiving carrier wave with the non-h copy CA and copy carrier wave (because of accurately tracking the signal)
Figure BDA0002679814490000111
And
Figure BDA0002679814490000112
present), then should be eliminated from the tracking process
Figure BDA0002679814490000113
And
Figure BDA0002679814490000114
comprises the following steps:
Figure BDA0002679814490000115
this part i(-h)(n) and q(-h)The expression (n) is purely the interference of the non-tracking signal h with the tracking signal h (assuming that the receiver has tracked all positioning signals received, in particular the stronger signals). When k ≠ h, it is generally absent
Figure BDA0002679814490000116
And
Figure BDA0002679814490000117
then does not exist
Figure BDA0002679814490000118
And
Figure BDA0002679814490000119
if it is
Figure BDA00026798144900001110
The interference of the received signal k with the integration result of the received signal h cannot be ignored, i.e. there should be:
Figure BDA00026798144900001111
coherent integration IQ value I of positioning signal h in N duration(+h)And Q(+h)Comprises the following steps:
Figure BDA00026798144900001112
expressing only the partial integral I of the tracking signal h(h)And Q(h)：
Figure BDA00026798144900001113
Expressing interference of only part of non-tracking signal h on tracking signal h
Figure BDA00026798144900001114
And
Figure BDA00026798144900001115
comprises the following steps:
Figure BDA00026798144900001116
namely, the method comprises the following steps:
Figure BDA0002679814490000121
by taking the advance (E), the instant (P) and the duplicate CA code of the positioning signal h respectivelySpreading sequence of lags (L)
Figure BDA0002679814490000122
And
Figure BDA0002679814490000123
and carrying out CA code stripping, carrier stripping and integration to respectively obtain the interference IQ values of advance, instant and lag:
Figure BDA0002679814490000124
using these interference IQ values and the above calculated
Figure BDA0002679814490000125
I.e. interference cancellation can be obtained by the above formula
Figure BDA0002679814490000126
Thereby achieving the purpose of accurately tracking each positioning signal.
The calculation operation method for eliminating the mutual interference among the signals is as follows (taking the elimination of the interference of all the non-tracking signals k to the tracking signal h as an example, the positioning signal k is also the tracking signal, and the signals with the intensity greater than that of the tracking signal h are correctly tracked, and the number of all the tracking signals is M):
step 1: the integral of all tracked positioning signals k (═ 1, 2.., M) is cleared
Figure BDA0002679814490000127
Figure BDA0002679814490000128
(i.e., set to 0), i.e., synchronizing the integration start sampling time of all tracked positioning signals k (1, 2.. multidot.m;. noteq.h) to the same integration start sampling time as the tracking signal h, but with the duplicate CA code sequence of each tracking signal
Figure BDA0002679814490000129
And copying the carrier phase sequence
Figure BDA00026798144900001210
Still generated by the tracking process of each location signal).
Step 2.1: performing early, instantaneous and late CA code stripping and carrier stripping of tracking signal h on received signal
Figure BDA00026798144900001211
And integrating the time length of N (multiple of the time length of the complete CA code broadcasting, and assuming 1 CA code broadcasting time length), actually including the mutual interference among the signals, and marking up as (+ h), and respectively obtaining the IQ integral values of advance, instant and lag
Figure BDA00026798144900001212
Step 2.2: respectively carrying out CA code stripping and carrier stripping on a positioning signal k (1, 2.., M ≠ h) of a receiving signal
Figure BDA00026798144900001213
(generated in the respective tracking module and can be directly referenced), and performing integration with the duration of N to obtain the instantaneous IQ integral value of each positioning signal k (1, 2.. multidot.m ≠ h)
Figure BDA0002679814490000131
Step 2.3: and (4) preprocessing mutual interference of positioning signals. In the calculation of the interference IQ value of the positioning signal k to the tracking signal h
Figure BDA0002679814490000132
And
Figure BDA0002679814490000133
of the positioning signal k
Figure BDA0002679814490000134
By using
Figure BDA0002679814490000135
Substitution,
Figure BDA0002679814490000136
By using
Figure BDA0002679814490000137
Instead of, and
Figure BDA0002679814490000138
and
Figure BDA0002679814490000139
and
Figure BDA00026798144900001310
Figure BDA00026798144900001311
already generated when tracking signals k and h, the signals are easy to calculate by using a trigonometric formula without additional calculation
Figure BDA00026798144900001312
And
Figure BDA00026798144900001313
thus removing
Figure BDA00026798144900001314
And
Figure BDA00026798144900001315
other parts can be synchronously calculated (i.e. preprocessed) in the tracking calculation process of the positioning signal h, besides the parts are not determined yet:
wherein the copied CA code sequence generated in the tracking process of each positioning signal
Figure BDA00026798144900001316
And copying the carrier phase sequence
Figure BDA00026798144900001317
The interference to the tracking signal h is obtained as follows
Figure BDA00026798144900001318
And
Figure BDA00026798144900001319
Figure BDA00026798144900001320
where y in the subscript denotes the preconditioned IQ value.
Step 2.4: for the result of step 2.3
Figure BDA00026798144900001321
And
Figure BDA00026798144900001322
integrating the time length N according to the following formula to obtain the interference preprocessing IQ value of each positioning signal k (═ 1, 2., M, ≠ h) on the tracking signal h:
Figure BDA00026798144900001323
Figure BDA00026798144900001324
Figure BDA00026798144900001325
and step 3: during a complete CA code broadcasting period of the positioning signal h, the CA code only modulates 1 data bit of the positioning message, so that during the CA code period
Figure BDA00026798144900001326
Is constant and is +1 or-1, and is obtained by taking the sign of the I path integral value of the IQ value, i.e. the IQ value after the coherent integration
Figure BDA00026798144900001327
And
Figure BDA00026798144900001328
as
Figure BDA00026798144900001329
And
Figure BDA00026798144900001330
initial value of (A), (B)
Figure BDA00026798144900001331
And
Figure BDA00026798144900001332
is the IQ value integration result of P-path CA code spreading sequence of received signal k with the same initial edge time length of N as tracking signal h, and is obtained by integrating for eliminating the interference of positioning signal k to tracking signal h, and the IQ integration value different from tracking signal k
Figure BDA0002679814490000141
And
Figure BDA0002679814490000142
but should be very close) to obtain
Figure BDA0002679814490000143
And
Figure BDA0002679814490000144
i.e. using the result of step 2.2
Figure BDA0002679814490000145
Figure BDA0002679814490000146
Instead of being actual
Figure BDA0002679814490000147
The position signal k (≠ h) is calculated as follows
Figure BDA0002679814490000148
And
Figure BDA0002679814490000149
Figure BDA00026798144900001410
and 4, step 4: the interference IQ component of each positioning signal k (═ 1, 2.., M ≠ h) on the tracking signal h is calculated according to the following formula
Figure BDA00026798144900001411
Figure BDA00026798144900001412
And 5: the interference of each positioning signal k (1, 2, M ≠ h) on the tracking signal h is eliminated according to the following formula, and the positioning signals do not interfere with each other
Figure BDA00026798144900001413
Figure BDA00026798144900001414
Step 6: using mutual interference without positioning signals
Figure BDA00026798144900001415
The receiver can achieve the purpose of accurately tracking the positioning signal h by performing code phase correction, carrier frequency and phase correction, and subsequent data bit decoding and TOA or TDOA measurement.
The above IQ value I(h)And Q(h)The interference of all other tracked positioning signals k | (-1, 2., M ≠ h) with the tracking signal h has been eliminated, but due to the calculation
Figure BDA00026798144900001416
And
Figure BDA00026798144900001417
is used
Figure BDA00026798144900001418
And
Figure BDA00026798144900001419
alternative(s)
Figure BDA00026798144900001420
And
Figure BDA00026798144900001421
from the superscript (+ k-h) it can be understood that:
(1)
Figure BDA00026798144900001422
and
Figure BDA00026798144900001423
is obtained by integrating the tracking signal h specially for eliminating the positioning signal k;
(2)
Figure BDA00026798144900001424
and
Figure BDA00026798144900001425
the integral starting sampling time is the same as the integral starting sampling time of the tracking signal h, and the integral duration is the same;
(3)
Figure BDA00026798144900001426
and
Figure BDA00026798144900001427
and
Figure BDA00026798144900001428
and
Figure BDA00026798144900001429
using duplicated instantaneous CA code stripping and duplicated carrier at the same sampling time
Figure BDA00026798144900001430
And
Figure BDA00026798144900001431
performing integration;
(4)
Figure BDA00026798144900001432
and
Figure BDA00026798144900001433
including interference from other positioning signals (≠ k);
(5)
Figure BDA0002679814490000151
and
Figure BDA0002679814490000152
including the tracking error of the positioning signal k;
(6) due to the different code phases of the positioning signal k and the positioning signal h, a data bit jump of the positioning signal k may exist within the integration duration N, which may cause an integration error.
Thus, calculated as above
Figure BDA0002679814490000153
And
Figure BDA0002679814490000154
there is a certain error.
And 7: to obtain more accurate lead, prompt and lag I(h)And Q(h)And eliminating the interference among all tracking signals h | ((1, 2.. multidot., M)) according to the steps 1-6 to obtain all tracking signals h | ((1, 2.. multidot., M)) actually meeting the precision requirement
Figure BDA0002679814490000155
The code phase, carrier frequency and phase of each positioning signal are corrected, and the subsequent data bit decoding and TOA or TDOA measurement are carried out, so that the receiver can accurately track both strong positioning signals and weak positioning signals.
It is also noted that in the devices, apparatuses, and methods of the present disclosure, each component or step can be decomposed and/or recombined. Such decomposition and/or recombination should be considered equivalents of the present disclosure.

Claims (6)

1. A method for eliminating mutual interference of strong and weak signals comprises the following steps:
performing early, instantaneous and late CA code stripping and carrier stripping of tracking signal h | ((1, 2.. multidot.M)) on the received signal
Figure FDA0002679814480000011
Integrating for N time length to obtain leading, real-time and lagging IQ integral values
Figure FDA0002679814480000012
Figure FDA0002679814480000013
And carrying out CA (rank order) code stripping and carrier stripping on a positioning signal k (1, 2,.. multidot.M;. noteh) of the tracking signal h | ((1, 2.. multidot.M)) on a receiving signal
Figure FDA0002679814480000014
Integrating the positioning signals with the time length of N to obtain the real-time IQ integral value of each positioning signal k (1, 2, M ≠ h)
Figure FDA0002679814480000015
Wherein the positioning signal k (═ 1, 2., M ≠ h) interferes with the tracking signal h | (-1, 2., M), which interferes with the tracking signal h | (-1, 2., M)
Figure FDA0002679814480000016
And
Figure FDA0002679814480000017
the integral starting sampling time is the same as the integral starting sampling time of the tracking signal h (═ 1, 2., M), and the integral duration is the same;
from duplicate CA code sequences generated during tracking of each positioning signal
Figure FDA0002679814480000018
And copying the carrier phase sequence
Figure FDA0002679814480000019
Obtaining interference to tracking signal h
Figure FDA00026798144800000110
And
Figure FDA00026798144800000111
y is expressed as a pre-processing IQ value;
interference to the tracking signal h
Figure FDA00026798144800000112
And
Figure FDA00026798144800000113
integrating the time length N to obtain an interference preprocessing IQ value of each positioning signal k (═ 1, 2., M, ≠ h) on the tracking signal h:
Figure FDA00026798144800000114
Figure FDA00026798144800000115
using the instantaneous IQ integral value
Figure FDA00026798144800000116
Instead of being actual
Figure FDA00026798144800000117
The signal amplitude of each positioning signal k (═ 1, 2.., M ≠ h) is calculated
Figure FDA00026798144800000118
And text data code
Figure FDA00026798144800000119
According to the signal amplitude of each positioning signal k (═ 1, 2.., M ≠ h)
Figure FDA00026798144800000120
And text data code
Figure FDA00026798144800000121
The interference IQ component of each positioning signal k (═ 1, 2.., M ≠ h) on tracking signal h is calculated
Figure FDA00026798144800000122
Figure FDA00026798144800000123
According to the interference IQ component of each positioning signal k (1, 2.., M ≠ h) to the tracking signal h
Figure FDA00026798144800000124
Figure FDA00026798144800000125
And the IQ integral value
Figure FDA00026798144800000126
Figure FDA0002679814480000021
Calculated to obtain signals without mutual interference of positioning signals
Figure FDA0002679814480000022
2. The method for canceling interference according to claim 1, wherein the method for canceling interference further comprises:
using mutual interference of said non-location signals
Figure FDA0002679814480000023
Code phase correction, carrier frequency and phase correction, and data bit decoding, TOA or TDOA measurements are performed.
3. A method of cancelling interference as claimed in claim 1, wherein the replicated CA code sequence generated by each positioning signal tracking procedure
Figure FDA0002679814480000024
And copying the carrier phase sequence
Figure FDA0002679814480000025
Obtaining interference to tracking signal h
Figure FDA0002679814480000026
And
Figure FDA0002679814480000027
the method comprises the following steps:
is calculated according to the following formula
Figure FDA0002679814480000028
Wherein
Figure FDA0002679814480000029
To locate the duplicate CA code spreading sequence of signal h,
Figure FDA00026798144800000210
is the phase of the replica carrier of the positioning signal h at the time instant of sample n.
4. The method of cancelling interference of claim 1, wherein the utilizing the interference cancellation signal
Figure FDA00026798144800000211
Figure FDA00026798144800000212
Instead of being actual
Figure FDA00026798144800000213
The signal amplitude of each positioning signal k (═ 1, 2.., M ≠ h) is calculated
Figure FDA00026798144800000214
And text data code
Figure FDA00026798144800000215
The method comprises the following steps:
is calculated according to the following formula
Figure FDA00026798144800000216
5. The method of cancelling interference according to claim 1, wherein a signal amplitude according to the respective positioning signal k (═ 1, 2.., M ≠ h)
Figure FDA00026798144800000217
And text data code
Figure FDA00026798144800000218
The interference IQ component of each positioning signal k (═ 1, 2.., M ≠ h) on tracking signal h is calculated
Figure FDA00026798144800000219
The method comprises the following steps:
is calculated according to the following formula
Figure FDA00026798144800000220
6. The method of cancelling interference according to claim 1, wherein an interfering IQ component of a tracking signal h is determined from the respective positioning signal k (═ 1, 2.., M ≠ h)
Figure FDA0002679814480000031
Calculated to obtain signals without mutual interference of positioning signals
Figure FDA0002679814480000032
The method comprises the following steps:
is calculated according to the following formula
Figure FDA0002679814480000033
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