CN114578394A - Signal tracking method and signal tracking device - Google Patents

Signal tracking method and signal tracking device Download PDF

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CN114578394A
CN114578394A CN202210231717.1A CN202210231717A CN114578394A CN 114578394 A CN114578394 A CN 114578394A CN 202210231717 A CN202210231717 A CN 202210231717A CN 114578394 A CN114578394 A CN 114578394A
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code
phase
subcarrier
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姚铮
漆耘含
陆明泉
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Tsinghua University
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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
    • 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
    • G01S19/29—Acquisition or tracking or demodulation of signals transmitted by the system carrier including Doppler, related
    • 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
    • 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
    • G01S19/35—Constructional details or hardware or software details of the signal processing chain
    • G01S19/37—Hardware or software details of the signal processing chain

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  • Radar, Positioning & Navigation (AREA)
  • Remote Sensing (AREA)
  • Computer Networks & Wireless Communication (AREA)
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Abstract

The application discloses a signal tracking method and a signal tracking device. The method comprises the following steps: receiving a broadband composite signal; the wideband composite signal comprises at least one upper sideband signal component and at least one lower sideband signal component; tracking the first target signal by using a first local time-of-day code to determine at least a current fusion phase and a current fusion frequency of the carrier and the subcarrier; tracking the second target signal by using the local instantaneous carrier to at least determine a current code phase, a current code frequency, a current subcarrier phase and a current subcarrier frequency; one of the first target signal and the second target signal is an upper sideband signal component, and the other is a lower sideband signal component; the first local instantaneous code is determined based on a previous code phase and a previous code frequency, and the local instantaneous carrier is determined based on a previous fused phase and a previous fused frequency. The method and the device solve the problem of coupling of the carrier phase and the subcarrier phase, and are higher in accuracy.

Description

Signal tracking method and signal tracking device
Technical Field
The embodiment of the application relates to the technical field of satellite navigation tracking, in particular to a signal tracking method and a signal tracking device.
Background
With the increasing demand for positioning accuracy, Global Navigation Satellite Systems (GNSS) are continuously updated. Since a subcarrier modulated signal has frequency domain separation characteristics, a wider root mean square bandwidth and higher ranging accuracy than a Binary Phase Shift Keying (BPSK) signal, a subcarrier modulated signal such as an AltBOC signal or an ACE-BOC wideband composite signal is generally used as a GNSS signal at present.
The AltBOC signal and the ACE-BOC broadband composite signal are both dual-frequency constant envelope composite signals, and in most cases both have four signal components, two of which are located in the lower sideband and the other two are located in the upper sideband. The power of the four signal components of the AltBOC signal are equal, while the power of the four signal components of the ACE-BOC wideband composite signal may be adjusted, i.e., the power of the four signal components of the ACE-BOC wideband composite signal may not be equal. Compared with the AltBOC signal, the power distribution of the signal component of the ACE-BOC broadband composite signal has higher flexibility, and can meet different design and application requirements of GNSS.
Although the ACE-BOC wideband composite signal typically has four signal components, in special cases, e.g. to meet specific application requirements, the number of signal components of the ACE-BOC wideband composite signal may be less than 4, when the power of one of the signal components may be modulated to zero. However, whether or not the ACE-BOC wideband composite signal has four signal components, the carrier phase and subcarrier phase of each of the signal components are heavily coupled.
The tracking technology adopted for the GNSS signals is generally DBT technology or ASYM-DBT technology. Among them, the DBT technique is only suitable for GNSS signals with equal signal component power, such as AltBOC signals, and cannot solve the problem of coupling between carrier phase and subcarrier phase. Although the ASYM-DBT technology can be suitable for GNSS signals with unequal signal component powers, the ASYM-DBT technology aims at a signal component amplitude domain, that is, the ASYM-DBT technology realizes signal tracking by estimating and normalizing each signal component power, that is, the ASYM-DBT technology equivalently converts a signal component with unequal power into a signal component with equal power and then adopts the DBT technology, and estimation of the signal component power is interfered by a plurality of factors and has very low accuracy, so that the normalized signal power is still unequal, and the subsequent DBT technology which cannot be adopted is caused. From the above, the existing tracking technology cannot solve the problem of coupling of carrier phase and subcarrier phase, and is not suitable for ACE-BOC broadband composite signals.
Disclosure of Invention
A signal tracking method according to a first aspect of the present application includes:
receiving a broadband composite signal; wherein the wideband composite signal comprises at least one upper sideband signal component and at least one lower sideband signal component;
tracking the first target signal by using a first local time-of-day code to determine at least a current fusion phase and a current fusion frequency of the carrier and the subcarrier; and
tracking the second target signal by using the local instantaneous carrier to at least determine a current code phase, a current code frequency, a current subcarrier phase and a current subcarrier frequency;
wherein one of the first target signal and the second target signal is the upper sideband signal component and the other is the lower sideband signal component; the first local time-of-day code is determined based on a previous code phase and a previous code frequency, and the local time-of-day carrier is determined based on a previous fused phase and a previous fused frequency.
A signal tracking apparatus according to a second aspect of the present application includes:
the receiving module is used for receiving the broadband composite signal; wherein the wideband composite signal comprises at least one upper sideband signal component and at least one lower sideband signal component
A carrier loop, which tracks the first target signal by using a first local time code to at least determine the current fusion phase and the current fusion frequency of the carrier and the subcarrier; and
a code loop and a subcarrier loop, wherein the local instantaneous carrier is utilized to track the second target signal so as to at least determine the current code phase, the current code frequency, the current subcarrier phase and the current subcarrier frequency;
wherein one of the first target signal and the second target signal is the upper sideband signal component and the other is the lower sideband signal component; the first local time-of-day code is determined based on a previous code phase and a previous code frequency, and the local time-of-day carrier is determined based on a previous fused phase and a previous fused frequency.
The signal tracking method and the signal tracking device provided by the embodiment of the application respectively track two different signal components, namely an upper sideband signal component and a lower sideband signal component, and share the fusion phase and the fusion frequency of a carrier and a subcarrier determined by tracking one of the signal components to the other signal component, so that when the signal components of the shared fusion phase and the fusion frequency are tracked, only the code phase, the code frequency, the subcarrier phase and the subcarrier frequency need to be determined, and the problem of coupling of the carrier phase and the subcarrier phase can be solved. Therefore, the method and the device have the advantages that the problem of coupling of the carrier phase and the subcarrier phase is solved by jointly processing and tracking the upper signal component and the lower signal component in a phase crossing auxiliary mode, the method and the device are suitable for the ACE-BOC broadband composite signal, the method and the device aim at the phase domain of the signal component without estimating the power of the signal component, the ASYM-DBT technology estimates the power of the signal component aiming at the amplitude domain of the signal component, and compared with the power estimation, the accuracy of phase tracking is higher.
It should be understood that the statements in this section do not necessarily identify key or critical features of the embodiments of the present application, nor do they limit the scope of the present application. Other features of the present application will become apparent from the following description.
Drawings
Other features, objects and advantages of the present application will become more apparent upon reading of the following detailed description of non-limiting embodiments thereof, made with reference to the accompanying drawings. The drawings are included to provide a better understanding of the present solution and are not intended to limit the present application. In the drawings:
FIG. 1 is a flow chart of a signal tracking method according to the present application;
FIG. 2 is a schematic diagram of one of the received wideband composite signals according to the signal tracking method of the present application;
FIG. 3 is a schematic diagram of another received wideband composite signal in accordance with the signal tracking method of the present application;
FIG. 4 is a partial schematic view of one of the signal tracking devices according to the present application;
FIG. 5 is a partial schematic view of another signal tracking device according to the present application;
FIG. 6 is a schematic diagram of carrier-to-noise ratio over time for tracking ACE-BOC signals using the signal tracking method of the present application and using existing BPSK-Like techniques, respectively;
FIG. 7 is a graph of autocorrelation functions of two lower sideband signal components during tracking of an ACE-BOC signal using the signal tracking method of the present application;
FIG. 8 is a schematic diagram of the variation of tracking error of tracking the ACE-BOC signal by the signal tracking method of the present application and by the existing BPSK-Like technique under different loop filtering conditions;
fig. 9 is a schematic diagram of the code-subtracted carrier wave over time for tracking the ACE-BOC signal using the signal tracking method of the present application and using the existing BPSK-Like technique, respectively.
Reference numerals:
100. a power main lobe of the upper sideband signal component;
200. a power main lobe of the lower sideband signal component; 300. a single signal channel;
310. a first signal path; 320. a second signal path;
400. a carrier digitally controlled oscillator; 410. a first correlator;
421. a first product correlator; 422. a first integral correlator; 430. a first phase detector;
500. a subcarrier digitally controlled oscillator; 510. a third correlator;
521. a second product correlator; 522. a third product correlator;
530. a second integral correlator; 540. a second phase discriminator;
600. a code numerically controlled oscillator; 610. and a third phase detector.
Detailed Description
In the description of the embodiments of the present application, the terms "first," "second," and "third" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.
The following description of the exemplary embodiments of the present application, taken in conjunction with the accompanying drawings, includes various details of the embodiments of the application for the understanding of the same, which are to be considered exemplary only. Accordingly, those of ordinary skill in the art will recognize that various changes and modifications of the embodiments described herein can be made without departing from the scope and spirit of the present application. Also, descriptions of well-known functions and constructions are omitted in the following description for clarity and conciseness.
It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict. The present application will be described in detail below with reference to the accompanying drawings in conjunction with embodiments.
In the related art, GNSS signals typically employ subcarrier modulated signals such as ACE-BOC wideband composite signals. Typically, an ACE-BOC wideband composite signal has four signal components, two of which are upper sideband signal components and two of which are lower sideband signal components. The power distribution of the four signal components of the ACE-BOC broadband composite signal has higher flexibility, and can meet different design and application requirements of GNSS.
The ACE-BOC broadband composite signal may be expressed as s (t):
Figure BDA0003540793820000051
wherein, PLIAnd PLQPower, P, of two lower sideband signal componentsUIAnd PUQThe power of the two upper sideband signal components respectively; s isLI(t) and sLQ(t) baseband spread spectrum signals, s, for two lower sideband signal components, respectivelyUI(t) and sUQ(t) baseband spread spectrum signals for the two upper sideband signal components, respectively; sc (sc)L(t) subcarrier signal, sc, of lower sideband signal componentU(t) a subcarrier signal being an upper sideband signal component; t iss＝1/fs，fsIs the subcarrier frequency; i isIM(t) is an intermodulation term, f0Is the carrier frequency.
Where the baseband spread spectrum signal in equation (1.1) is used to maintain the constant envelope property of the corresponding signal component, the baseband spread spectrum signal of the upper sideband signal component or the lower sideband signal component can be expressed as:
Figure BDA0003540793820000052
wherein L belongs to { L, U }, and X belongs to { I, Q }; s isLI(t) and sLQ(t) baseband spread spectrum signals, s, for two lower sideband signal components, respectivelyUI(t) and sUQ(t) baseband spread spectrum signals for the two upper sideband signal components, respectively; dLI(t) and dLQ(t) navigation text bits carried by the two lower sideband signal components, dUI(t) and dUQ(t) navigation message bits carried by the two upper sideband signal components, respectively; c. CLI(t) and cLQ(t) spread-spectrum code signals, c, being the components of two lower sideband signals, respectivelyUI(t) and cUQ(t) spread spectrum code signals for the two upper sideband signal components, respectively;
Figure BDA0003540793820000053
Figure BDA0003540793820000054
and
Figure BDA0003540793820000055
spreading code sequences respectively employed for the two lower sideband signal components,
Figure BDA0003540793820000056
and
Figure BDA0003540793820000057
spreading code sequences respectively adopted for the two upper sideband signal components;
Figure BDA0003540793820000061
Figure BDA0003540793820000062
and
Figure BDA0003540793820000063
the code rates of the two lower sideband signal components,
Figure BDA0003540793820000064
and
Figure BDA0003540793820000065
code rates of two upper sideband signal components respectively; p (t) represents a rectangular pulse in
Figure BDA0003540793820000066
The value of the interval t is 1, and the values of the rest intervals t are 0.
Since the main power lobe of the ACE-BOC wideband composite signal is wide, and the bandwidth of the rf front end of the receiving module in the related art is equal to or slightly larger than the main power lobe of the ACE-BOC wideband composite signal, that is, the bandwidth of the rf front end of the receiving module only contains the main power lobe of the ACE-BOC wideband composite signal, the subcarrier signal of the ACE-BOC wideband composite signal can be simplified into a sinusoidal signal, and thus the simplified ACE-BOC wideband composite signal can be represented as r (t):
Figure BDA0003540793820000067
wherein, PLIAnd PLQPower, P, of two lower sideband signal componentsUIAnd PUQThe power of the two upper sideband signal components respectively; sLI(t) and sLQ(t) baseband spread spectrum signals, s, for two lower sideband signal components, respectivelyUI(t) and sUQ(t) baseband spread spectrum signals for the two upper sideband signal components, respectively; τ is the propagation delay of the signal; f. ofsIs the subcarrier frequency; f. ofdIs a Doppler shift;
Figure BDA0003540793820000068
is the initial carrier phase.
The formula (1.3) can be expressed as follows:
r(t)＝rLI(t)-rLQ(t)+rUI(t)-rUQ(t)； (1.4)
wherein the content of the first and second substances,
Figure BDA0003540793820000069
Figure BDA00035407938200000610
Figure BDA00035407938200000611
Figure BDA00035407938200000612
Figure BDA00035407938200000613
θ＝2πfsτ；
wherein r isLI(t) and rLQ(t) two lower sideband signal components, rUI(t) and rUQ(t) two upper sideband signal components, respectively; pLIAnd PLQPower, P, of two lower sideband signal componentsUIAnd PUQThe power of the two upper sideband signal components respectively; sLI(t) and sLQ(t) baseband spread spectrum signals, s, for two lower sideband signal components, respectivelyUI(t) and sUQ(t) baseband spread spectrum signals for the two upper sideband signal components, respectively; τ is the signal propagation delay; f. of0Is the carrier frequency; f. ofdIs a Doppler shift; f. ofsIs the subcarrier frequency; phi is the carrier phase and theta is the subcarrier phase.
From this, it can be seen from equation (1.4) that the carrier phase and the subcarrier phase of each signal component of the ACE-BOC wideband composite signal, i.e. the upper sideband signal component or the lower sideband signal component, are contained in the same sine function or cosine function, i.e. the carrier phase and the subcarrier phase of each signal component are strongly coupled. The existing tracking technology such as DBT technology or ASYM-DBT technology can not solve the problem of coupling of carrier phase and subcarrier phase, and is not suitable for ACE-BOC broadband composite signals.
In addition, from the above equation (1.4), it can be seen that the lower sideband signal component, i.e., rLI(t) or rLQ(t) signal propagation delay τ, carrier frequency f0Doppler shift fdAnd the sum carrier phase phi and the upper sideband signal component r respectivelyUI(t) or rUQ(t) signal propagation delay τ, carrier frequency f0Doppler shift fdThe same value as the carrier phase phi, and the lower sideband signal component rLI(t) or rLQ(t) subcarrier frequency fsAnd the sum subcarrier phase theta is respectively associated with the upper sideband signal component rUI(t) or rUQ(t) subcarrier frequency fsAnd the subcarrier phase theta takes the opposite value. It can be seen that the carrier phase phi and subcarrier phase theta of the lower sideband signal component are strongly correlated with the carrier phase phi and subcarrier phase theta of the upper sideband signal component.
Based on this, in order to solve the above problem, as shown in fig. 1, an embodiment of the present application provides a signal tracking method, including:
s100, receiving a broadband composite signal; wherein the wideband composite signal comprises at least one upper sideband signal component and at least one lower sideband signal component;
s200, tracking the first target signal by using a first local time-of-day code to at least determine the current fusion phase and the current fusion frequency of the carrier and the subcarrier;
s300, tracking the second target signal by using a local instant carrier to at least determine a current code phase, a current code frequency, a current subcarrier phase and a current subcarrier frequency;
wherein one of the first target signal and the second target signal is an upper sideband signal component and the other is a lower sideband signal component; the first local instantaneous code is determined based on a previous code phase and a previous code frequency, and the local instantaneous carrier is determined based on a previous fused phase and a previous fused frequency.
According to the method, two different signal components, namely an upper sideband signal component and a lower sideband signal component, are tracked respectively, and the fusion phase and the fusion frequency of a carrier and a subcarrier determined by tracking one signal component are shared by the other signal component, so that when the signal components of the shared fusion phase and the fusion frequency are tracked, only the code phase, the code frequency, the subcarrier phase and the subcarrier frequency need to be determined, and then the problem of coupling of the carrier phase and the subcarrier phase can be solved. Therefore, the method and the device have the advantages that the problem of coupling of the carrier phase and the subcarrier phase is solved by jointly processing and tracking the upper signal component and the lower signal component in a phase crossing auxiliary mode, the method and the device are suitable for the ACE-BOC broadband composite signal, the method and the device aim at the phase domain of the signal component without estimating the power of the signal component, the ASYM-DBT technology estimates the power of the signal component aiming at the amplitude domain of the signal component, and compared with the power estimation, the accuracy of phase tracking is higher.
The following describes each step of the signal tracking method in the embodiment of the present application in detail.
Step S100
The wideband composite signal may be received in a number of ways, for example:
first, a single-channel wideband reception method, as shown in fig. 2, step S100 includes:
s110, receiving the upper sideband signal component and the lower sideband signal component simultaneously using the single signal channel 300; specifically, the center frequency point of the radio frequency front end of the receiving module is placed at the center frequency point between the upper sideband signal component and the lower sideband signal component, the filter of the receiving module is a low-pass filter, and the bandwidth of the low-pass filter, that is, the receiving bandwidth of the single signal channel 300, covers the power main lobe 100 of the upper sideband signal component and the power main lobe 200 of the lower sideband signal component.
Second, a dual-channel narrowband reception method, as shown in fig. 3, step S100 includes:
s110, receiving the upper sideband signal component by using a first signal channel 310;
s120, receiving a lower sideband signal component by adopting a second signal channel 320 which is independent from and arranged in parallel with the first signal channel 310;
specifically, as shown in fig. 3, the center frequency point of the rf front end of the receiving module is placed at the center frequency point between the upper sideband signal component and the lower sideband signal component, the first filter of the receiving module is a band-pass filter, the bandwidth of the first filter, that is, the receiving bandwidth of the first signal channel 310, covers the power main lobe 100 of the upper sideband signal component, the second filter of the receiving module is also a band-pass filter, and the bandwidth of the second filter, that is, the receiving bandwidth of the second signal channel 320, covers the power main lobe 200 of the lower sideband signal component.
As can be seen from the above, the receiving bandwidth of the single signal path 300 in the first mode is very wide, and the receiving bandwidth of the first signal path 310 and the receiving bandwidth of the second signal path 320 in the second mode are both narrow. In the case that the filtering resources of the rf front end of the receiving module are sufficient, the wideband composite signal may be received in a first or second manner. However, in the case of insufficient filtering resources at the rf front end of the receiving module, for example, in the case that the receiving bandwidth of the single signal channel 300 cannot cover the power main lobe 100 of the upper sideband signal component and the power main lobe 200 of the lower sideband signal component, the wideband composite signal can only be received in the second mode.
Furthermore, it should be noted that, since the first mode only employs one signal channel, the upper sideband signal component and the lower sideband signal component are received synchronously, and the phases of the two components are kept always, and the second mode employs the first signal channel 310 and the second signal channel 320 to receive the upper sideband signal component and the lower sideband signal component respectively, compared with the first mode, in order to ensure that the phase of the upper sideband signal component and the phase of the lower sideband signal component are kept consistent in the second mode, step S110 and step S120 in the second mode need to be performed synchronously, that is, the time when the upper sideband signal component is received by the first signal channel 310 is the same as the time when the lower sideband signal component is received by the second signal channel 320.
Still taking the ACE-BOC wideband composite signal as an example below, the ACE-BOC wideband composite signal comprises two upper sideband signal components, rUI(t) and rUQ(t) and two lower sideband signal components, i.e., rLI(t) and rLQ(t)。
Taking the first mode as an example, the upper sideband signal component and the lower sideband signal component synchronously received by the receiving module are r respectivelyUI(t) and rLI(t), i.e. the signal r to be trackedI(t) is rUI(t)+rLI(t) of (d). As can be seen from the above equation (1.4),
Figure BDA0003540793820000091
Figure BDA0003540793820000092
if the above sideband signal component rUI(t) as a reference phase, and the upper sideband signal component rUI(t) can be represented by
Figure BDA0003540793820000093
Figure BDA0003540793820000094
Wherein phi isUI(t)＝2πfUI+γ，fUI＝f0+fd+fsAnd γ is φ - θ. Based on this, the lower sideband signal component rLI(t) then can be represented as
Figure BDA0003540793820000095
Figure BDA0003540793820000096
Wherein, thetaL(t)＝-2πfs,Lt+μ，fs,L＝2fsAnd μ ═ 2 θ. It can be seen that thetaL(t) tracking theta with respect to subcarrier only and carrier independentL(t) is not affected by the carrier phase. In this way,
Figure BDA0003540793820000097
of course, the upper sideband signal component and the lower sideband signal component synchronously received at the receiving module are r respectivelyUI(t) and rLI(t), the lower sideband signal component r may beLI(t) as a reference phase, i.e. the lower sideband signal component rLI(t) can be represented by
Figure BDA0003540793820000098
Figure BDA0003540793820000099
Wherein phi isLI(t)＝2π(f0+fd-fs) t + φ + θ. Then, the upper sideband signal component rUI(t) then can be represented as
Figure BDA00035407938200000910
Thus, in the case of mode one, there are 8 types of signals to be tracked:
first, upper sideband signal component rUI(t) as a reference phase, the signal r to be trackedI(t) is rUI(t)+rLI(t)；
Second, lower sideband signal component rLI(t) as a reference phase, the signal r to be trackedI(t) is rUI(t)+rLI(t)；
Third, upper sideband signal component rUQ(t) as a reference phase, the signal r to be trackedIQ(t) is rUQ(t)+rLI(t)；
Fourth, lower sideband signal component rLI(t) as a reference phase, the signal r to be trackedIQ(t) is rUQ(t)+rLI(t)；
Fifth and above sideband signal component rUI(t) as a reference phase, the signal r to be trackedI(t) is rUI(t)+rLQ(t)；
Sixth, lower sideband signal component rLQ(t) as a reference phase, the signal r to be trackedI(t) is rUI(t)+rLQ(t)；
Seventh and upper sideband signal component rUQ(t) as a reference phase, the signal r to be trackedI(t) is rUQ(t)+rLQ(t)；
Eighth, lower sideband signal component rLQ(t) as a reference phase, the signal r to be trackedI(t) is rUQ(t)+rLQ(t)。
Similarly, in the case of the second method, there are 8 types of signals to be tracked. The signals to be tracked in the first mode and the second mode are 16 types, so that compared with the prior art, the method has higher flexibility and can meet different application requirements.
Step S200
To determine the current phase of the carrier and subcarrier combination, step S200 includes:
s210, carrying out carrier stripping on the broadband composite signal based on the previous fusion phase and the previous fusion frequency to obtain a baseband signal of a first target signal;
s220, determining a target correlation value corresponding to the first target signal according to the baseband signal of the first target signal and the first local time code;
s230, performing phase discrimination according to the target correlation value to determine a fusion phase error and a current fusion frequency;
and S240, updating the previous fusion phase according to the fusion phase error to obtain the current fusion phase.
Referring to fig. 4 and 5, the first signal to be tracked mentioned above is taken as an example, i.e. the signal r to be trackedI(t) is rUI(t)+rLI(t) the reference phase being the upper sideband signal component rUI(t) phase phiUI(t) for example, a specific procedure for obtaining the current fusion phase is described:
s210, based on the previous fusion phase
Figure BDA0003540793820000111
And the previous fusion frequency fUICarrying out carrier stripping on the broadband composite signal, namely the signal r to be trackedI(t) performing carrier stripping. Specifically, the carrier numerically controlled oscillator 400 is utilized to fuse phases based on the previous one
Figure BDA0003540793820000112
And the previous fusion frequency fUIGenerating local instant carrier
Figure BDA0003540793820000113
Wherein the content of the first and second substances,
Figure BDA0003540793820000114
fUI＝f0+fd+fs，f0is the carrier frequency; f. ofdIs a Doppler shift; f. ofsIs the subcarrier frequency. Calculating the product of the wideband composite signal and the local instantaneous carrier, i.e. calculating rI(t) and
Figure BDA0003540793820000115
to obtain a baseband of the first target signalSignal sUI(t-τ)。
S220, according to the baseband signal S of the first target signalUI(t- τ) and a first local time-of-day code
Figure BDA0003540793820000116
A target correlation value corresponding to the first target signal is determined. As an example, the target correlation value comprises a first correlation value IUI,PAnd a second correlation value QUI,P. Specifically, in the first integration interval [0, T]Base band signal s of internal pair first target signalUI(t- τ) and a first local time-of-day code
Figure BDA0003540793820000117
Is integrated to obtain a first correlation value IUI,PAnd a second correlation value QUI,P：
Figure BDA0003540793820000118
Wherein R belongs to { I, Q }, RI(t) is the signal to be tracked,
Figure BDA0003540793820000119
is a local instantaneous carrier wave and is,
Figure BDA00035407938200001110
is the first local time-of-day code, T is the coherent integration time,
Figure BDA00035407938200001111
is the previous code phase;
the first correlation value I thus obtained by calculating the formula (1.5)UI,PAnd a second correlation value QUI,P：
Figure BDA00035407938200001112
Figure BDA00035407938200001113
Wherein d isUIFor the upper sideband signal component rUI(t) carrying navigation message bits, PUIFor the upper sideband signal component rUI(ii) the power of (t),
Figure BDA00035407938200001114
for a baseband signal sUI(T), T is the coherent integration time,
Figure BDA00035407938200001115
for the previous code phase, sinc (Δ f)UIT)＝sin(πΔfUIT)/(πΔfUIT)，ΔfUIFor the upper sideband signal component rUI(t) a fusion frequency error, Δ γ being the upper sideband signal component rUI(t) phase error.
Since Δ f is used to realize stable tracking UI0, so the above equations (1.6) and (1.7) can be collated as:
Figure BDA00035407938200001116
Figure BDA00035407938200001117
s230, according to the target correlation value, namely the first correlation value IUI,PAnd a second correlation value QUI,PCarrying out phase discrimination to determine a fusion phase error delta gamma and a current fusion frequency; specifically, based on the formula (1.8) and the formula (1.9), the following formula can be employed to calculate the fusion phase error Δ γ:
Figure BDA0003540793820000121
s240, updating the previous fusion phase according to the fusion phase error delta gamma
Figure BDA0003540793820000122
To obtain the current fusion phase.
It should be noted that any phase detector capable of implementing step S230 in the art may be used to determine the fusion phase error and the current fusion frequency when step S230 is executed. For example, the phase detector may be, but is not limited to, a carrier tracking loop phase detector.
Step S300
To determine the current code phase and the current subcarrier phase, step S300 includes:
s310, carrying out carrier stripping on the broadband composite signal based on the local instant carrier to obtain a baseband signal of a second target signal;
s320, determining an early correlation value, an instantaneous correlation value and a delay correlation value corresponding to the second target signal according to the baseband signal, the previous code phase, the previous code frequency, the previous subcarrier phase and the previous subcarrier frequency of the second target signal
S330, performing phase discrimination according to the early correlation value and the delayed correlation value to determine a code phase error and a current code frequency;
s340, updating the previous code phase according to the code phase error to obtain the current code phase;
s350, performing phase discrimination according to the target correlation value and the instant correlation value to determine subcarrier phase errors and current subcarrier frequencies;
and S360, updating the previous subcarrier phase according to the subcarrier phase error so as to obtain the current subcarrier phase.
Next, still taking the first signal to be tracked as an example, a specific step of acquiring the current code phase and the current subcarrier phase is described:
s310, receiving local instant carrier
Figure BDA0003540793820000123
And based on local instantaneous carrier
Figure BDA0003540793820000124
The wideband composite signal is subjected to carrier stripping, specifically, the product of the wideband composite signal and the local instantaneous carrier is calculated, namely r is calculatedI(t) and
Figure BDA0003540793820000125
to obtain a baseband signal s of the second target signalLI(t-τ)。
S320, base band signal S according to second target signalLI(t- τ), previous code phase
Figure BDA0003540793820000131
Previous code frequency, previous subcarrier phase
Figure BDA0003540793820000132
And previous subcarrier frequency
Figure BDA0003540793820000133
An advance correlation value, an immediate correlation value, and a delay correlation value corresponding to the second target signal are determined. As an example, the advanced correlation value comprises a first advanced correlation value ILI,EAnd a second advanced correlation value QLI,EThe instantaneous correlation value includes a first instantaneous correlation value ILI,PAnd a second instantaneous correlation value QLI,pThe delay correlation value includes a first delay correlation value ILI,LAnd a second delay correlation value QLI,L. Specifically, the method comprises the following steps: s321, controlling the oscillator 600 according to the previous code phase by using the code number
Figure BDA0003540793820000134
Generating a first local time-of-day code from a previous code frequency
Figure BDA0003540793820000135
Local advance code
Figure BDA0003540793820000136
Second local time code
Figure BDA0003540793820000137
And local delayLate code
Figure BDA0003540793820000138
S322, using the sub-carrier digital controlled oscillator 500 to control the oscillator according to the previous sub-carrier phase
Figure BDA0003540793820000139
And previous subcarrier frequency
Figure BDA00035407938200001310
Generating a local instantaneous subcarrier scLI(t); wherein the content of the first and second substances,
Figure BDA00035407938200001311
Figure BDA00035407938200001312
s323, base band signal S according to second target signalLI(t- τ), local instantaneous subcarrier scLI(t), local advance code
Figure BDA00035407938200001313
Second local time code
Figure BDA00035407938200001314
And local delay code
Figure BDA00035407938200001315
Determining a first early correlation value ILI,ESecond advanced correlation value QLI,EA first instantaneous correlation value ILI,PA second instantaneous correlation value QLI,pA first delay correlation value ILI,LAnd a second delay correlation value QLI,L。
S330, according to the first advanced correlation value ILI,ESecond advanced correlation value QLI,EA first delay correlation value ILI,LAnd a second delay correlation value QLI,LPerforming phase discrimination to determine code phase error
Figure BDA00035407938200001316
And the current code frequency; in particular, the amount of the solvent to be used,the code phase error can be calculated using the following equation:
Figure BDA00035407938200001317
s340, according to the code phase error
Figure BDA00035407938200001318
Updating previous code phase
Figure BDA00035407938200001319
To obtain a current code phase;
s350, according to the first correlation value IUI,PSecond correlation value QUI,PA first instantaneous correlation value ILI,PA second instantaneous correlation value QLI,pPhase discrimination is performed to determine the subcarrier phase error Δ μ and the current subcarrier frequency. Specifically, the subcarrier phase error Δ μmay be calculated using the following equation:
Figure BDA00035407938200001320
s360, updating the previous subcarrier phase according to the subcarrier phase error delta mu
Figure BDA00035407938200001321
To obtain the current subcarrier phase.
It should be noted that, when step S330 is executed, any phase detector capable of implementing step S330 in the art may be used to determine the code phase error and the code frequency. For example, the phase detector may be, but is not limited to, a code tracking loop phase detector. Similarly, any phase detector in the art capable of implementing step S350 may be used to determine the subcarrier phase error and the subcarrier frequency when step S350 is performed. For example, the phase detector may be, but is not limited to, a subcarrier tracking loop phase detector.
Wherein, the step S323 may include:
(ii) in the second integration region, for example, the following formula (2.1) is usedIntermediate to the base band signal s of the second target signalLI(t- τ), local instantaneous subcarrier scLI(t) and local advance code
Figure BDA0003540793820000141
Is integrated to obtain a first advanced correlation value ILI,EAnd a second advanced correlation value QLI,E：
Figure BDA0003540793820000142
Wherein R belongs to { I, Q }, RI(t) is the signal to be tracked,
Figure BDA0003540793820000143
for local instantaneous carrier, scLI(t) is the local instantaneous sub-carrier,
Figure BDA0003540793820000144
for the local advance code, T is the coherent integration time,
Figure BDA0003540793820000145
for the previous code phase, δETo cost-advance the amount of delay of the code.
The first and second advanced correlation values are thus obtained by calculating equation (2.1):
Figure BDA0003540793820000146
Figure BDA0003540793820000147
wherein d isLIFor the lower sideband signal component rLI(t) carrying navigation message bits, PUIFor the lower sideband signal component rLI(ii) the power of (t),
Figure BDA0003540793820000148
for a baseband signal sLI(t) autocorrelation function, δETo cost-advance the delay amount of the code, T is the coherent integration time,
Figure BDA0003540793820000149
for the previous code phase, sinc ((Δ f)UI-Δfs,L)T)＝sin(π(ΔfUL-Δfs,L)T)/(π(ΔfUL-Δfs,L)T)，ΔfULFor the lower sideband signal component rLI(t) carrier frequency error, Δ fs,LFor the lower sideband signal component rLI(t) subcarrier frequency error, Δ γ lower sideband signal component rLI(t) fused phase error, Δ μ lower sideband signal component rLI(t) subcarrier phase error.
Since Δ f is used to realize stable trackingUL≈0，Δf s,L0, so the above equations (2.2) and (2.3) can be collated as:
Figure BDA00035407938200001410
Figure BDA00035407938200001411
second, the following formula is adopted, and the baseband signal s of the second target signal is subjected to the second integration intervalLI(t-tau), local instantaneous subcarrier scLI(t) and a second local time code
Figure BDA0003540793820000151
Is integrated to obtain a first instantaneous correlation value ILI,PAnd a second immediate correlation value QLI,p。
Figure BDA0003540793820000152
The calculation principle is the same as that of the first step, and the calculation principle can be obtained through the formulaFirst instantaneous correlation value ILI,PAnd a second immediate correlation value QLI,p：
Figure BDA0003540793820000153
Figure BDA0003540793820000154
Wherein d isLIFor the lower sideband signal component rLI(t) carrying navigation message bits, PUIFor the lower sideband signal component rLI(ii) the power of (t),
Figure BDA0003540793820000155
for a baseband signal sLI(t) autocorrelation function, δEThe amount of delay to generate the second local time-of-day code, T is the coherent integration time,
Figure BDA0003540793820000156
for the previous code phase, Δ γ is the lower sideband signal component rLI(t) fused phase error, Δ μ lower sideband signal component rLI(t) subcarrier phase error.
Thirdly, adopting the following formula to carry out the baseband signal s of the second target signal in the second integration intervalLI(t- τ), local instantaneous subcarrier scLI(t) and local delay code
Figure BDA0003540793820000157
Is integrated to obtain a first delayed correlation value ILI,LAnd a second delay correlation value QLI,L。
Figure BDA0003540793820000158
The calculation principle is the same as that of the first step, and the first instantaneous correlation value I can be obtained through the formulaLI,LAnd a second immediate correlation value QLI,L：
Figure BDA0003540793820000159
Figure BDA00035407938200001510
Wherein d isLIFor the lower sideband signal component rLI(t) carrying navigation message bits, PUIFor the lower sideband signal component rLI(ii) the power of (t),
Figure BDA00035407938200001511
for a baseband signal sLI(t) autocorrelation function, δLT is the coherent integration time,
Figure BDA00035407938200001512
for the previous code phase, Δ γ is the lower sideband signal component rLI(t) fused phase error, Δ μ lower sideband signal component rLI(t) subcarrier phase error.
In addition, after step S300 is executed, the signal tracking method according to the embodiment of the present application further includes:
s400, according to the current code phase
Figure BDA0003540793820000161
Current subcarrier phase
Figure BDA0003540793820000162
And the current subcarrier frequency fsDetermining a current signal propagation delay
Figure BDA0003540793820000163
Wherein, the step S400 can be implemented by the following formula (3.1):
Figure BDA0003540793820000164
wherein, Ts＝1/fs,L，fs,L＝2fs。
As can be seen from the above, in the embodiment of the present application, the two-dimensional non-ambiguity tracking technique is adopted in step S200 and step S300 to estimate the phase domain of the signal component and not the power of the signal component. Compared with the ASYM-DBT technology, the method and the device have the advantage that the accuracy of phase tracking is higher when the amplitude domain of the signal component, namely the power of the signal component, is estimated. In addition, the subcarrier frequency tracked by the existing DBT technology and ASYM-DBT technology is fsThe signal tracking method of the present application tracks twice the subcarrier frequency, i.e., 2fs. The higher the tracked subcarrier frequency is, the higher the accuracy of the subcarrier phase obtained by phase discrimination is, so that the accuracy of the subcarrier phase obtained by the signal tracking method is higher than that obtained by adopting a DBT technology and an ASYM-DBT technology, and the accuracy of subsequent ranging based on the broadband composite signal is higher.
In addition, as shown in fig. 4 and 5, an embodiment of the present application further provides a signal tracking apparatus, which includes a receiving module, a carrier loop, a code loop, and a subcarrier loop. Wherein the receiving module receives a wideband composite signal, the wideband composite signal comprising at least one upper sideband signal component and at least one lower sideband signal component. Wherein the carrier loop tracks the first target signal with the first local-time-code to determine at least a current fused phase and a current fused frequency of the carrier and the subcarrier. Wherein the code loop and the subcarrier loop track the second target signal using the local instantaneous carrier to determine at least a current code phase, a current code frequency, a current subcarrier phase, and a current subcarrier frequency.
Wherein one of the first target signal and the second target signal is an upper sideband signal component and the other is a lower sideband signal component; the first local instantaneous code is determined based on a previous code phase and a previous code frequency, and the local instantaneous carrier is determined based on a previous fused phase and a previous fused frequency.
As shown in fig. 2 and 3, the receiving module structure does not receive the broadband composite signal at the same time in different ways, for example:
in case the receiving module comprises a single signal channel 300, the receiving module receives the upper sideband signal component and the lower sideband signal component synchronously using the single signal channel 300. Specifically, the center frequency point of the radio frequency front end of the receiving module is placed at the center frequency point between the upper sideband signal component and the lower sideband signal component, the filter of the receiving module is a low-pass filter, and the bandwidth of the low-pass filter, that is, the receiving bandwidth of the single signal channel 300, covers the power main lobe 100 of the upper sideband signal component and the power main lobe 200 of the lower sideband signal component.
In case the receiving module comprises a first signal path 310 and a second signal path 320, the first signal path 310 and the second signal path 320 are arranged independently and in parallel to each other, and the receiving module receives the upper sideband signal component and the lower sideband signal component synchronously using the first signal path 310 and the second signal path 320, respectively. Specifically, the center frequency point of the radio frequency front end of the receiving module is placed at the center frequency point between the upper sideband signal component and the lower sideband signal component, the first filter of the receiving module is a band-pass filter, the bandwidth of the first filter, that is, the receiving bandwidth of the first signal channel 310, covers the power main lobe 100 of the upper sideband signal component, the second filter of the receiving module is also a band-pass filter, and the bandwidth of the second filter, that is, the receiving bandwidth of the second signal channel 320, covers the power main lobe 200 of the lower sideband signal component.
As shown in fig. 4 and 5, the carrier loop includes a carrier numerically controlled oscillator 400, i.e., a carrier NCO, a first correlator 410, a second correlator, and a first phase detector 430. Wherein, the carrier numerically controlled oscillator 400 generates a local instantaneous carrier according to the previous fusion phase and the previous fusion frequency and updates the previous fusion phase according to the fusion phase error to obtain the current fusion phase; the first correlator 410 calculates the product of the wideband composite signal and the local instantaneous carrier to obtain a baseband signal of the first target signal; the second correlator determines a target correlation value corresponding to the first target signal, namely a first correlation value and a second correlation value according to the baseband signal of the first target signal and the first local time code; the first phase detector 430 determines a fused phase error and a fused frequency from the first correlation value and the second correlation value and feeds back the fused phase error and the fused frequency to the carrier numerically controlled oscillator 400.
In some embodiments, the code loop and subcarrier loop include subcarrier numerically controlled oscillator 500, i.e., subcarrier NCO, code numerically controlled oscillator 600, i.e., code NCO, second phase detector 540, third phase detector 610, third correlator 510, and fourth correlator. The third correlator 510 performs carrier stripping on the wideband composite signal based on the local instantaneous carrier to obtain a baseband signal of the second target signal. Wherein the subcarrier numerically controlled oscillator 500 generates a local instantaneous subcarrier from a previous subcarrier phase and a previous subcarrier frequency and updates the previous subcarrier phase according to the subcarrier phase error to obtain a current subcarrier phase. The code numerically controlled oscillator 600 generates a first local time code, a local advance code, a second local time code and a local delay code according to the previous code phase and the previous code frequency, and updates the previous code phase according to the code phase error to obtain the current code phase. And the fourth correlator determines an advance correlation value, an instantaneous correlation value and a delay correlation value corresponding to the second target signal according to the baseband signal, the local instantaneous subcarrier, the local advance code, the second local instantaneous code and the local delay code of the second target signal. As an example, the advance correlation value includes a first advance correlation value and a second advance correlation value, the immediate correlation value includes a first immediate correlation value and a second immediate correlation value, and the delay correlation value includes a first delay correlation value and a second delay correlation value. The second phase detector 540 determines a code phase error and a current code frequency according to the early correlation value and the late correlation value, and feeds the code phase error and the current code frequency back to the code numerically controlled oscillator 600. The third phase detector 610 determines a subcarrier phase error and a current subcarrier frequency according to the target correlation value and the instantaneous correlation value, and feeds back the subcarrier phase error and the current subcarrier frequency to the subcarrier numerically controlled oscillator 500.
As an example, the first phase detector 430 may be, but is not limited to, a carrier tracking loop phase detector, the second phase detector 540 may be, but is not limited to, a code tracking loop phase detector, and the third phase detector 610 may be, but is not limited to, a subcarrier tracking loop phase detector.
Further, the second correlator comprises a first product correlator 421 and a first integral correlator 422, and the fourth correlator comprises a second product correlator 521, a third product correlator 522 and a second integral correlator 530.
Wherein, the carrier numerically controlled oscillator 400, the first correlator 410, the second correlator and the first phase detector 430 are connected in sequence; the output end of the receiving module is connected with the input ends of the first correlator 410 and the third correlator 510 respectively; the first product correlator 421 is connected to the output end of the code numerically controlled oscillator 600, and is configured to receive the first local time code generated by the code numerically controlled oscillator 600, so as to calculate the product of the baseband signal of the first target signal and the first local time code; the input of the first integration correlator 422 is connected to the output of the first product correlator 421 for integrating the product of the baseband signal of the first target signal and the first local time-instant code during a first integration interval to obtain a first correlation value and a second correlation value. The output of the first integrating correlator 422 is connected to the input of the first phase detector 430 and the input of the third phase detector 610, respectively, and the output of the first phase detector 430 is connected to the input of the carrier dco 400. The output end of the carrier digital control oscillator 400 is connected with the input end of the third correlator 510, and the third correlator 510 performs carrier stripping on the broadband composite signal based on the local instantaneous carrier generated by the carrier digital control oscillator 400 to obtain a baseband signal of a second target signal; the second product correlator 521 is respectively connected to the output terminal of the subcarrier dco 500 and the output terminal of the third correlator 510, and is configured to receive the local instantaneous subcarrier generated by the subcarrier dco 500 and calculate the product of the local instantaneous subcarrier and the baseband signal of the second target signal; the third product correlator 522 has inputs coupled to the output of the second product correlator 521 and the output of the code numerically controlled oscillator 600, respectively, for calculating the product of the local advance code, the second local time-of-day code, and the local delay code generated by the code numerically controlled oscillator 600 and the output of the second product correlator 521, respectively. An input of the second integral correlator 530 is connected to an input of the third product correlator 522 for integrating the output of the second product correlator 521 over a second integration interval to obtain a first early correlation value, a second early correlation value, a first immediate correlation value, a second immediate correlation value, a first late correlation value and a second late correlation value. The output end of the second integral correlator 530 is connected to the input ends of the second phase detector 540 and the third phase detector 610, the output end of the second phase detector 540 is connected to the input end of the code numerically controlled oscillator 600, and the output end of the third phase detector 610 is connected to the input end of the subcarrier numerically controlled oscillator 500.
The first signal to be tracked mentioned above is taken as an example in the following, i.e. the signal r to be trackedI(t) is rUI(t)+rLI(t) reference phase is the upper sideband signal component rUI(t) phase phiUI(t) for example, the operation principle of the carrier loop will be explained:
as shown in fig. 4 and 5, the carrier numerically controlled oscillator 400 fuses phases according to the previous
Figure BDA0003540793820000191
And the previous fusion frequency fUIGenerating local instant carrier
Figure BDA0003540793820000192
The first correlator 410 is based on the signal r to be tracked output by the receiving moduleI(t) and the local instantaneous carrier output by the carrier numerically controlled oscillator 400
Figure BDA0003540793820000193
Calculating to obtain a baseband signal s of the first target signalUI(t- τ); first product correlator 421 receives baseband signal s of first target signalUI(t- τ) and a first local time-of-flight code generated by code numerically controlled oscillator 600
Figure BDA0003540793820000194
Calculating a baseband signal s of a first target signalUI(t- τ) and a first local time-of-day code
Figure BDA0003540793820000195
The first integral correlator 422 during a first integration interval 0, T]Base band signal s of internal pair first target signalUI(t-tau) and a first local time-of-day code
Figure BDA0003540793820000196
Is integrated to obtain a first correlation value IUI,PAnd a second correlation value QUI,P(ii) a The first phase detector 430 detects the first correlation value IUI,PAnd a second correlation value QUI,PAnd performing phase discrimination, outputting a fusion phase error delta gamma obtained by the phase discrimination and the current fusion frequency to the carrier numerically controlled oscillator 400, updating the previous fusion phase by the carrier numerically controlled oscillator 400 according to the fusion phase error to obtain the current fusion phase, and taking the fusion phase and the fusion frequency as the previous fusion phase and the previous fusion frequency required by the next tracking cycle respectively.
Similarly, the carrier numerically controlled oscillator 400 will generate a local instantaneous carrier
Figure BDA0003540793820000201
Transmitted to the third correlator 510, the third correlator 510 calculates the local instantaneous carrier
Figure BDA0003540793820000202
And a signal r to be trackedI(t) to obtain a baseband signal s of the second target signalLI(t- τ). The subcarrier digitally controlled oscillator 500 will be based on the previous subcarrier phase
Figure BDA0003540793820000203
And previous subcarrier frequency
Figure BDA0003540793820000204
Generated local instantaneous subcarrier scLI(t) transmitting to the second product correlationThe second product correlator 521 calculates the baseband signal s of the second target signalLI(t-T) and local instantaneous subcarrier scLI(t) is obtained. The code numerically controlled oscillator 600 will be based on the previous code phase
Figure BDA0003540793820000205
Generating local advance code with previous code frequency
Figure BDA0003540793820000206
Second local time code
Figure BDA0003540793820000207
And local delay code
Figure BDA0003540793820000208
Transmitted to the third multiply correlator 522, the third multiply correlator 522 calculates the local advance code
Figure BDA0003540793820000209
Second local time code
Figure BDA00035407938200002010
And local delay code
Figure BDA00035407938200002011
Respectively, with the output values of the second product correlator 521. Second integral correlator 530 integrates the input value of second product correlator 521 over a second integration interval to determine first advanced correlation value ILI,ESecond advanced correlation value QLI,EA first instantaneous correlation value ILI,PA second instantaneous correlation value QLI,pA first delay correlation value ILI,LAnd a second delay correlation value QLI,L. The second phase detector 540 detects the first advanced correlation value ILI,ESecond advanced correlation value QLI,EA first delay correlation value ILI,LAnd a second delay correlation value QLI,LPerforming phase discrimination to determine code phase error
Figure BDA00035407938200002012
And the current code frequency, and the code phase error
Figure BDA00035407938200002013
And the current code frequency is fed back to the code numerically controlled oscillator 600. The code numerically controlled oscillator 600 is based on the code phase error
Figure BDA00035407938200002014
Updating previous code phase
Figure BDA00035407938200002015
To obtain the current code phase, which in turn can be used as the previous code phase and previous code frequency, respectively, needed for the next tracking cycle. The third phase detector 610 operates according to the first correlation value IUI,PSecond correlation value QUI,PA first instantaneous correlation value ILI,PA second instantaneous correlation value QLI,pPhase discrimination is performed to determine the subcarrier phase error Δ μ and the current subcarrier frequency and the subcarrier phase error Δ μ and the current subcarrier frequency are fed back to the subcarrier numerically controlled oscillator 500. Subcarrier numerically controlled oscillator 500 updates the previous subcarrier phase based on subcarrier phase error Δ μ
Figure BDA0003540793820000211
To obtain the current subcarrier phase, which in turn can be used as the previous subcarrier phase and the previous subcarrier frequency, respectively, needed for the next tracking cycle.
In addition, the signal tracking device further comprises a delay calculation module, wherein the delay calculation module is used for determining the current signal propagation delay according to the current code phase, the current subcarrier phase and the current subcarrier frequency.
The signal tracking device in the embodiment of the application is adopted to carry out simulation test as follows:
as shown in Table 1, the simulation test is directed to an ACE-BOC broadband composite signal superimposed with white noise with different powers, and the signal to be tracked is still rI(t) the reference phase is the upper sidebandSignal component rUI(t) phase phiUI(t)。
TABLE 1 ACE-BOC broadband composite signal parameter table
Parameter(s) Parameter value
Satellite numbering C19
Intermediate frequency 0MHz
Data format I&Q
Sampling rate 60MHz
Carrier to noise ratio 40～50dB-Hz
Signal component power ratio (P)LI:PLQ:PUI:PUQ) 1:1.2:0.5:1.4
As shown in table 2, the carrier Loop is a Phase-Locked Loop (PLL), the code Loop is a digital delay-Locked Loop (DLL), and the Subcarrier Loop is a Subcarrier tracking Loop (SLL).
TABLE 2 parameter tables for carrier, code and subcarrier loops
Parameter(s) Parameter value
PLL order
2
PLL loop filter bandwidth 5Hz
DLL order
2
DLL loop filter bandwidth 1/2/5Hz
DLL early-late interval 0.5chips
Number of SLL steps 2
SLL Loop Filter Bandwidth 1/2/5Hz
Coherent integration time T 1ms
As shown in fig. 6, it is found through simulation experiments that the carrier-to-noise ratio generated by using the signal tracking method in the embodiment of the present application is substantially the same as the carrier-to-noise ratio generated by using the existing BPSK-Like tracking technique. Due to the fact thatThe existing BPSK-Like tracking technology is to use the upper sideband signal component rUI(t) and a lower sideband signal component rLI(t) are tracked as separate signals, respectively, whereas in the present application the upper sideband signal component r is trackedUI(t) and a lower sideband signal component rLIAnd (t) joint tracking is carried out simultaneously, so that the carrier-to-noise ratios of the two are basically the same, which indirectly proves that the signal tracking method has strong stability.
As shown in fig. 7, the signal tracking method of the present application tracks twice the subcarrier frequency, i.e., 2fsLower sideband signal component rLIThe autocorrelation function envelope of (t) is consistent with that of a BPSK signal, thereby also demonstrating that the accuracy of the subcarrier phase and the code phase obtained by the signal tracking method of the present application is high.
In addition, as shown in fig. 8, it is found through simulation experiments that the thermal noise performance of the signal tracking method in the embodiment of the present application is better than the thermal noise performance generated by the existing BPSK-Like tracking technology under different loop filter bandwidths. Compared with the BPSK-Like tracking technology, the signal tracking method in the embodiment of the application has smaller tracking error. In addition, as shown in fig. 9, in the case that the loop bandwidth is 5Hz and the carrier-to-noise ratio is 50dB-Hz, compared with the BPSK-Like tracking technology, the fluctuation of the Code Minus Carrier (CMC) in the signal tracking method in the embodiment of the present application is smaller, and it can be seen that the signal tracking method in the embodiment of the present application can improve the accuracy of ranging.
It should be understood that various forms of the flows shown above may be used, with steps reordered, added, or deleted. For example, the steps described in the present disclosure may be executed in parallel, sequentially, or in different orders, and are not limited herein as long as the desired results of the technical solutions disclosed in the present disclosure can be achieved.
The above-described embodiments are not intended to limit the scope of the present disclosure. It will be apparent to those skilled in the art that various modifications, combinations, sub-combinations, and substitutions may be made in accordance with design requirements, which may mean other factors. Any modification, equivalent replacement, and improvement made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims (17)

1. A signal tracking method, comprising:
receiving a broadband composite signal; wherein the wideband composite signal comprises at least one upper sideband signal component and at least one lower sideband signal component;
tracking the first target signal by using a first local time-of-day code to determine at least a current fusion phase and a current fusion frequency of the carrier and the subcarrier; and
tracking the second target signal by using the local instantaneous carrier to at least determine a current code phase, a current code frequency, a current subcarrier phase and a current subcarrier frequency;
wherein one of the first target signal and the second target signal is the upper sideband signal component and the other is the lower sideband signal component; the first local time-of-day code is determined based on a previous code phase and a previous code frequency, and the local time-of-day carrier is determined based on a previous fused phase and a previous fused frequency.
2. The signal tracking method of claim 1, wherein receiving a wideband composite signal comprises:
receiving the upper sideband signal component and the lower sideband signal component simultaneously using a single signal channel;
wherein a receive bandwidth of the single signal path covers a power main lobe of the upper sideband signal component and a power main lobe of the lower sideband signal component.
3. The signal tracking method of claim 1, wherein receiving a wideband composite signal comprises:
receiving the upper sideband signal component using a first signal path; wherein a receive bandwidth of the first signal path covers a power main lobe of the upper sideband signal component; and
receiving the lower sideband signal component by adopting a second signal channel which is independent from and arranged in parallel with the first signal channel; wherein a receive bandwidth of the second signal path covers a power main lobe of the lower sideband signal component.
4. A signal tracking method according to any of claims 1 to 3, wherein tracking the first target signal using the first local-time code to determine at least a current fused phase and a current fused frequency of the carrier and the subcarrier comprises:
performing carrier stripping on the wideband composite signal based on the previous fusion phase and the previous fusion frequency to obtain a baseband signal of the first target signal;
determining a target correlation value corresponding to the first target signal according to a baseband signal of the first target signal and the first local time-of-day code;
performing phase discrimination according to the target correlation value to determine a fusion phase error and the current fusion frequency; and
and updating the previous fusion phase according to the fusion phase error so as to obtain the current fusion phase.
5. The signal tracking method of claim 4, wherein carrier stripping the wideband composite signal based on the previous fused phase and the previous fused frequency to obtain a baseband signal of the first target signal comprises:
generating a local instantaneous carrier from the previous fusion phase and the previous fusion frequency by using a carrier numerically controlled oscillator; and
and calculating the product of the broadband composite signal and the local instantaneous carrier to obtain a baseband signal of the first target signal.
6. The signal tracking method of claim 4, wherein determining a target correlation value corresponding to the first target signal from the baseband signal of the first target signal and the first local time-of-day code comprises:
integrating a product of a baseband signal of the first target signal and the first local time-of-day code over a first integration interval to obtain the target correlation value.
7. The signal tracking method of claim 4, wherein tracking the second target signal with the local instantaneous carrier to determine at least a current code phase, a current code frequency, a current subcarrier phase, and a current subcarrier frequency comprises:
carrying out carrier stripping on the broadband composite signal based on the local instantaneous carrier to obtain a baseband signal of the second target signal;
determining an early correlation value, an instantaneous correlation value, and a late correlation value corresponding to the second target signal according to a baseband signal of the second target signal, a previous code phase, a previous code frequency, a previous subcarrier phase, and a previous subcarrier frequency;
performing phase discrimination according to the early correlation value and the delayed correlation value to determine a code phase error and the current code frequency;
updating the previous code phase according to the code phase error to obtain the current code phase;
performing phase discrimination according to the target correlation value and the instantaneous correlation value to determine a subcarrier phase error and the current subcarrier frequency; and
and updating the previous subcarrier phase according to the subcarrier phase error so as to obtain the current subcarrier phase.
8. The signal tracking method of claim 7, wherein determining an early correlation value, an immediate correlation value, and a late correlation value corresponding to the second target signal based on a baseband signal of the second target signal, a previous code phase, a previous code frequency, a previous subcarrier phase, and a previous subcarrier frequency comprises:
generating a first local immediate code, a local advance code, a second local immediate code and a local delay code from a previous code phase and a previous code frequency using a code numerically controlled oscillator;
generating a local instantaneous subcarrier from the previous subcarrier phase and the previous subcarrier frequency using a subcarrier numerically controlled oscillator; and
determining the early correlation value, the immediate correlation value, and the late correlation value based on a baseband signal of the second target signal, the local immediate subcarrier, the local early code, the second local immediate code, and the local late code.
9. The signal tracking method of claim 8, wherein determining the advance correlation value, the immediate correlation value, and the delay correlation value from a baseband signal of the second target signal, the local immediate subcarrier, the local advance code, the second local immediate time code, and the local delay code comprises:
integrating the product of the baseband signal of the second target signal, the local instantaneous subcarrier and the local advance code over a second integration interval to obtain the advance correlation value;
integrating, over the second integration interval, a product of a baseband signal of the second target signal, the local instantaneous subcarrier, and the second local instantaneous code to obtain the instantaneous correlation value; and
integrating the product of the baseband signal of the second target signal, the local instantaneous subcarrier, and the local delay code over the second integration interval to obtain the delay correlation value.
10. The signal tracking method according to any one of claims 1 to 3,
after receiving the local instantaneous carrier and tracking another signal component in the wideband composite signal as a second target signal, the signal tracking method further includes:
determining a current signal propagation delay based on the current code phase, the current subcarrier phase, and the current subcarrier frequency.
11. A signal tracking apparatus, comprising:
the receiving module is used for receiving the broadband composite signal; wherein the wideband composite signal comprises at least one upper sideband signal component and at least one lower sideband signal component;
a carrier loop for tracking the first target signal by using the first local time-of-day code to determine at least a current fusion phase and a current fusion frequency of the carrier and the subcarrier; and
a code loop and a subcarrier loop, tracking the second target signal by using a local instantaneous carrier to determine at least a current code phase, a current code frequency, a current subcarrier phase and a current subcarrier frequency;
wherein one of the first target signal and the second target signal is the upper sideband signal component and the other is the lower sideband signal component; the first local time-of-day code is determined based on a previous code phase and a previous code frequency, and the local time-of-day carrier is determined based on a previous fused phase and a previous fused frequency.
12. The signal tracking device of claim 11, wherein the receive module comprises a single signal path having a receive bandwidth that covers both the power main lobe of the upper sideband signal component and the power main lobe of the lower sideband signal component.
13. The signal tracking device of claim 11, wherein the receiving module comprises a first signal path and a second signal path, the first signal path and the second signal path being independent of each other and arranged in parallel; the receive bandwidth of the first signal path covers the power main lobe of the upper sideband signal component, and the receive bandwidth of the second signal path covers the power main lobe of the lower sideband signal component.
14. The signal tracking device of any of claims 11 to 13, wherein the carrier loop comprises:
a carrier numerically controlled oscillator for generating a local instantaneous carrier according to the previous fused phase and the previous fused frequency, and updating the previous fused phase according to a fused phase error to obtain the current fused phase;
a first correlator for calculating the product of the wideband composite signal and the local instantaneous carrier to obtain a baseband signal of the first target signal;
a second correlator for determining a target correlation value corresponding to the first target signal according to the baseband signal of the first target signal and the first local time-of-flight code;
and the first phase detector is used for determining the fusion phase error and the current fusion frequency according to the target correlation value and feeding back the fusion phase error and the current fusion frequency to the carrier digital control oscillator.
15. The signal tracking device of claim 14, wherein the code loop and subcarrier loop comprise:
the third correlator is used for carrying out carrier stripping on the broadband composite signal based on the local instant carrier so as to obtain a baseband signal of the second target signal;
a subcarrier numerically controlled oscillator for generating a local instantaneous subcarrier from a previous subcarrier phase and a previous subcarrier frequency and for updating the previous subcarrier phase based on a subcarrier phase error to obtain a current subcarrier phase;
a code numerically controlled oscillator for generating a first local time-of-day code, a local advance code, a second local time-of-day code, and a local retard code based on a previous code phase and a previous code frequency, and for updating the previous code phase based on a code phase error to obtain a current code phase;
a fourth correlator for determining an advance correlation value, an immediate correlation value, and a delay correlation value corresponding to the second target signal according to the baseband signal of the second target signal, the local immediate subcarrier, the local advance code, the second local immediate code, and the local delay code;
the second phase discriminator determines the code phase error and the current code frequency according to the advance correlation value and the delay correlation value and feeds the code phase error and the current code frequency back to the code digital control oscillator;
and the third phase discriminator determines the subcarrier phase error and the current subcarrier frequency according to the target correlation value and the instantaneous correlation value and feeds the subcarrier phase error and the current subcarrier frequency back to the subcarrier digital control oscillator.
16. The signal tracking device of claim 15, wherein the first phase detector is a carrier tracking loop phase detector, the second phase detector is a code tracking loop phase detector, and/or the third phase detector is a subcarrier tracking loop phase detector.
17. The signal tracking device of any one of claims 11 to 13, further comprising:
and the delay calculation module determines the current signal propagation delay according to the current code phase, the current subcarrier phase and the current subcarrier frequency.
CN202210231717.1A 2022-03-10 2022-03-10 Signal tracking method and signal tracking device Pending CN114578394A (en)

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN117214925A (en) * 2023-09-28 2023-12-12 北京凯芯微科技有限公司 Broadband composite navigation signal tracking method
CN117452451A (en) * 2023-12-01 2024-01-26 辽宁天衡智通防务科技有限公司 Tracking method, device and medium for authorization signal in global positioning system signal

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN117214925A (en) * 2023-09-28 2023-12-12 北京凯芯微科技有限公司 Broadband composite navigation signal tracking method
CN117452451A (en) * 2023-12-01 2024-01-26 辽宁天衡智通防务科技有限公司 Tracking method, device and medium for authorization signal in global positioning system signal
CN117452451B (en) * 2023-12-01 2024-03-22 辽宁天衡智通防务科技有限公司 Tracking method, device and medium for authorization signal in global positioning system signal

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