A method and receiver for receiving and processing non-cooperative spread spectrum signals based on multiple antennas

Abstract

The present invention discloses a method and a receiver for receiving and processing non-cooperative spread spectrum signals based on multiple antennas, and belongs to the field of navigation and positioning technology. The invention installs at least two array antennas on an application platform, both of which have beam forming and pointing capabilities; the receiver loop is composed of a signal filter assisted by predicted parameters, a frequency detector, a direct sampling signal tracking loop, and an antenna feedback control loop. The present invention can provide backup navigation and positioning guarantee when satellite navigation is unavailable, which is of great significance for emergency backup navigation applications.

Description

Technical Field

[0001] The present invention belongs to the technical field of navigation and positioning, and in particular relates to a method and a receiver for receiving and processing non-cooperative spread spectrum signals based on multiple antennas. Background Art

[0002] Currently, satellite navigation has been widely used in personal, vehicle, aviation, and maritime scenarios. However, due to the low receiving power of satellite navigation signals, it is very susceptible to electromagnetic interference and positioning failure. Using non-cooperative signals broadcast by ground or satellite platforms to achieve positioning has become a potential backup navigation method.

[0003] The conventional satellite navigation receiver loop design method is to use the locally generated pseudo code and the received signal for correlation processing after down-conversion, bandpass filtering and frequency detection of the received signal, use the I / Q branch correlator integral value to adjust the local carrier phase to achieve signal carrier tracking, and use the lead-lag phase detector to detect the correlator output peak to achieve pseudo code synchronization and tracking, and calculate the ranging value through the parameters of carrier tracking and pseudo code tracking output.

[0004] However, for non-cooperative signals, since their pseudo code sequences are unknown, it is impossible to track the signals through a conventional receiver loop. Summary of the invention

[0005] The purpose of the present invention is to provide a multi-antenna based non-cooperative spread spectrum signal reception and processing method and receiver, which can be used for application scenarios where satellite navigation is missing but the coordinate position of the non-cooperative spread spectrum signal source is known, and solve the signal tracking capability required for the application platform to achieve its own positioning.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is:

[0007] A method for receiving and processing a non-cooperative spread spectrum signal based on multiple antennas comprises the following steps:

[0008] (1) Install at least two array antennas on the application platform, both with beamforming and pointing capabilities; construct a receiver loop consisting of a signal filter assisted by known parameters, a frequency detector, a direct sampling signal tracking loop, and an antenna feedback control loop;

[0009] (2) In the antenna feedback control loop, the instantaneous initial coordinates, attitudes and radiation source positions of the receiver's multiple antennas are used to calculate and determine the beamforming parameters of each array antenna so that the beams of the multiple antennas are all pointed to the radiation source of the non-cooperative spread spectrum signal;

[0010] (3) Input the multi-antenna received signal into the signal filter, and perform down-conversion and bandpass filtering on the non-cooperative spread spectrum signal received by each array antenna based on the known information of the frequency point, bandwidth and modulation mode of the non-cooperative spread spectrum signal, retain the multi-channel sampling signal within the frequency band where the non-cooperative signal is located, and input it into the frequency detector;

[0011] (4) The frequency detector uses the instantaneous initial coordinates, attitudes and radiation source positions of the multiple antennas of the receiver to calculate the frequency difference between the non-cooperative spread spectrum signals received by the multiple antennas, and then fine-tunes the frequency of the multi-channel sampling signal to keep it consistent, and inputs it into the direct sampling signal tracking loop;

[0012] (5) The direct sampling signal tracking loop takes one of the input multi-channel sampling signals as the reference, denoted as s1; performs secondary down-conversion on the other signals, with the frequency adjustment value being f0. The down-converted signals are denoted as s2 to s n ; Generate a carrier with frequency f0 and adjustable phase locally as the local carrier loop reference frequency signal pair s2~s n Modulation mixing is performed, and correlation processing is performed with s1 to obtain the carrier phase difference with s1 respectively; at the same time, the lead-lag phase detector is used to compare s1 with the mixed s2~s n Perform correlation processing to obtain the time delay difference of multi-channel sampling signals as output;

[0013] (6) The receiver uses the output to calculate and update its own position, and outputs it to the antenna feedback control loop and frequency detector; and repeats steps (2) to (6).

[0014] A non-cooperative spread spectrum signal receiver based on multiple antennas, comprising a receiver loop and at least two array antennas, wherein the array antennas have beam forming and pointing capabilities, and the receiver loop is composed of a signal filter assisted by predicted parameters, a frequency detector, a direct sampling signal tracking loop, and an antenna feedback control loop.

[0015] The antenna feedback control loop uses the instantaneous initial coordinates, attitudes and radiation source positions of the receiver's multiple antennas to calculate and determine the beamforming parameters of each array antenna, so that the beams of the multiple antennas are all pointed to the radiation source of the non-cooperative spread spectrum signal.

[0016] The signal filter receives the multi-antenna receiving signal input from the outside, and performs down-conversion and bandpass filtering on the non-cooperative spread spectrum signal received by each array antenna through the pre-known information of the frequency point, bandwidth and modulation mode of the non-cooperative spread spectrum signal, retains the multi-channel sampling signal in the frequency band where the non-cooperative signal is located, and inputs it to the frequency detector;

[0017] The frequency detector uses the instantaneous initial coordinates, attitudes and radiation source positions of the receiver's multiple antennas to calculate the frequency difference between the non-cooperative spread spectrum signals received by the multiple antennas, and then fine-tunes the frequency of the multi-channel sampling signal to keep it consistent, and inputs it into the direct sampling signal tracking loop;

[0018] The direct sampling signal tracking loop takes one of the input multi-channel sampling signals as the reference, denoted as s1; performs secondary down-conversion on the other signals, with the frequency adjustment value being f0, and the down-converted signals are denoted as s2~s n ; Generate a carrier with frequency f0 and adjustable phase locally as the local carrier loop reference frequency signal pair s2~s n Modulation mixing is performed, and correlation processing is performed with s1 to obtain the carrier phase difference with s1 respectively; at the same time, the lead-lag phase detector is used to compare s1 with the mixed s2~s n Perform correlation processing to obtain the time delay difference of multi-channel sampling signals as output;

[0019] The receiver uses the output to calculate and update its own position and outputs it to the antenna feedback control loop and frequency detector.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] 1. The present invention can utilize multiple antennas installed on the same application platform to implement tracking and processing of non-cooperative spread spectrum signals through direct sampling signal correlation processing of different antennas, and obtain TDOA observation values ​​of non-cooperative spread spectrum signals reaching multiple antennas.

[0022] 2. The present invention can improve the signal tracking capability under the conditions of multiple non-cooperative spread spectrum signals and low signal receiving power.

[0023] 3. The present invention can utilize position-assisted antenna beam pointing control to improve the weak signal tracking capability of multiple antennas.

[0024] 4. The present invention can be applied to application scenarios where satellite navigation is missing but there is a non-cooperative spread spectrum signal source with known coordinates, and can solve the signal tracking capability required for the application platform to achieve its own positioning. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic diagram of the principle of an embodiment of the present invention. DETAILED DESCRIPTION

[0026] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments.

[0027] A method for receiving and processing a non-cooperative spread spectrum signal based on multiple antennas comprises the following steps:

[0028] (1) Install at least two array antennas on the application platform, both with beamforming and pointing capabilities; the receiver loop is composed of a signal filter assisted by known parameters, a frequency detector, a direct sampling signal tracking loop, and an antenna feedback control loop;

[0029] (2) In the antenna feedback control loop, the instantaneous initial coordinates, attitudes and radiation source positions of the receiver's multiple antennas are used to calculate and determine the beamforming parameters of each array antenna so that the beams of the multiple antennas are all pointed to the radiation source of the non-cooperative spread spectrum signal;

[0030] (3) Input the multi-antenna received signal into the signal filter, and perform down-conversion and bandpass filtering on the non-cooperative spread spectrum signal received by each array antenna based on the known information such as the frequency, bandwidth and modulation style of the non-cooperative spread spectrum signal, retain the multi-channel sampling signal within the frequency band where the non-cooperative signal is located, and input it into the frequency detector;

[0031] (4) The frequency detector uses the instantaneous initial coordinates, attitudes and radiation source positions of the multiple antennas of the receiver to calculate the frequency difference between the non-cooperative spread spectrum signals received by the multiple antennas, and then fine-tunes the frequency of the multi-channel sampling signal to keep it consistent, and inputs it into the direct sampling signal tracking loop;

[0032] (5) The direct sampling signal tracking loop takes one of the input multi-channel sampling signals as the reference, denoted as s1; performs secondary down-conversion on the other signals, with the frequency adjustment value being f0. The down-converted signals are denoted as s2 to s n ; Generate a carrier with frequency f0 and adjustable phase locally as the local carrier loop reference frequency signal pair s2~s n Modulation mixing is performed, and correlation processing is performed with s1 to obtain the carrier phase difference with s1 respectively; at the same time, the lead-lag phase detector is used to compare s1 with the mixed s2~s n Perform correlation processing to obtain the time delay difference of multi-channel sampling signals as output;

[0033] (6) The receiver uses the output to calculate and update its own position, and outputs it to the antenna feedback control loop and frequency detector; and repeats steps (2) to (6).

[0034] The non-cooperative spread spectrum signal radiation source in step (2) refers to a radiation source whose relative position relative to the receiver's multiple antennas is known, whose signal frequency and modulation pattern are known, and whose signal message and pseudo code are unknown.

[0035] A non-cooperative spread spectrum signal receiver based on multiple antennas, comprising a receiver loop and at least two array antennas, wherein the array antennas have beam forming and pointing capabilities, and the receiver loop is composed of a signal filter assisted by predicted parameters, a frequency detector, a direct sampling signal tracking loop, and an antenna feedback control loop.

[0036] The antenna feedback control loop calculates and determines the beamforming parameters of each array antenna so that the beams of multiple antennas are all directed to the radiation source of the non-cooperative spread spectrum signal;

[0037] The signal filter uses the pre-known information such as the frequency, bandwidth and modulation style of the non-cooperative spread spectrum signal to down-convert and band-pass filter the non-cooperative spread spectrum signal received by each array antenna.

[0038] The frequency detector fine-tunes the frequency of multi-channel sampling signals to keep the frequency consistent;

[0039] The direct sampling signal tracking loop uses one of the input multi-channel sampling signals as a reference and uses other signals as adjustment quantities for correlation processing to obtain the relative delay values ​​of signals received by different antennas.

[0040] The receiver uses the loop output to calculate and update its own position and outputs it to the antenna feedback control loop and frequency detector.

[0041] Repeat the above steps to achieve continuous tracking.

[0042] The receiver can receive and process unknown pseudo-code characteristic spread spectrum signals. It designs a receiver loop based on multiple antennas on the non-cooperative signal measurement and utilization architecture based on the direct signal processing method. The loop consists of a signal filter assisted by known parameters, a frequency detector, a direct sampling signal tracking loop, and an antenna feedback control loop. Based on this, it supports the use of multiple antennas installed on the same application platform to track non-cooperative spread spectrum signals through the direct sampling signal correlation processing process of different antennas, and uses position-assisted antenna beam pointing control to improve the weak signal tracking capability of multiple antennas.

[0043] Here is a more specific example:

[0044] like Figure 1 As shown, a method for receiving and processing a non-cooperative spread spectrum signal based on multiple antennas is shown. This example takes the tracking of a non-cooperative communication satellite signal by an aircraft equipped with multiple antennas as an example. The specific steps are as follows:

[0045] (1) Two array antennas are installed on the aircraft platform, both of which have beam forming and pointing capabilities; the receiver loop is composed of a signal filter assisted by known parameters, a frequency detector, a direct sampling signal tracking loop, and an antenna feedback control loop;

[0046] (2) The spacecraft starts moving from a position with known coordinates at time t0. At this time, the initial positions of the two array antennas are P1(t0) and P2(t0), respectively. The position of the non-cooperative communication satellite is calculated by orbital position estimation to be P s (t0), which is input into the antenna feedback control loop, thereby calculating the space vector P of the non-cooperative communication satellite relative to the two antennas s (t0)-P1(t0) and P s (t0)-P2(t0); then, combined with the instantaneous three-axis attitude value obtained by the current aircraft through inertial navigation and other means, and the installation attitude of the two array antennas on the aircraft body, the vectors r1(t0) and r2(t0) of the non-cooperative communication satellite relative to the axes of the two antennas are calculated, and the beamforming parameters of the two array antennas are controlled on this basis, so that the beams of the two antennas are both directed to the non-cooperative communication satellite;

[0047] (3) The signals received by the two antennas are input into the signal filter, and the predicted frequency point f of the non-cooperative spread spectrum signal of the communication satellite is used to filter the received signals. s (t0), bandwidth, modulation style and other information, down-convert and bandpass filter the non-cooperative spread spectrum signals received by the two array antennas, retain the multi-channel sampling signals in the frequency band where the non-cooperative signals are located, and input them into the frequency detector;

[0048] (4) The frequency detector uses the instantaneous coordinates P1(t0) and P2(t0) of the two antennas of the receiver and the position of the non-cooperative communication satellite P s (t0), as well as the speed and attitude of the aircraft at time t0, the instantaneous relative velocity difference between the two array antennas and the non-cooperative communication satellite is calculated.

[0049]

[0050] Where v1(t0) and v2(t0) are the speeds of the two antennas corresponding to the aircraft's speed and attitude. s (t0) Get the instantaneous frequency difference between signals

[0051]

[0052] Where c is the speed of light. The sampling signal frequency of channel 2 is fine-tuned to keep the sampling signal frequencies of the two channels consistent and input into the direct sampling signal tracking loop.

[0053] (5) The direct sampling signal tracking loop uses the sampling signal of array antenna 1 as a reference, denoted as s1; performs secondary down-conversion on the sampling signal of array antenna 2, with the frequency adjustment value being f0, and the down-converted signal is denoted as s2; a carrier with a frequency of f0 and adjustable phase is generated locally, and is used as the local carrier loop reference frequency signal to modulate and mix s2, and is correlated with s1 to obtain the carrier phase difference with s1; at the same time, an advance-lag phase detector is used to correlate s1 with the mixed s2 to obtain the relative delay difference between the sampling signals of array antenna 1 and array antenna 2 as the output;

[0054] (6) The receiver uses the output to calculate and update its current position, and outputs it to the antenna feedback control loop and frequency detector; and repeats steps (2) to (6).

[0055] In summary, the present invention can realize the tracking and processing of non-cooperative spread spectrum signals and obtain the TDOA observation values ​​of non-cooperative spread spectrum signals arriving at multiple antennas; it can improve the signal tracking capability under the conditions of multiple non-cooperative spread spectrum signals and low signal receiving power.

[0056] The present invention can provide backup navigation and positioning guarantee when satellite navigation is unavailable, and is of great significance for emergency backup navigation applications.

Claims

1. A method for receiving and processing a non-cooperative spread spectrum signal based on multiple antennas, characterized in that: The following steps are involved: (1) Install at least two array antennas on the application platform, both with beamforming and pointing capabilities; construct a receiver loop consisting of a signal filter assisted by known parameters, a frequency detector, a direct sampling signal tracking loop, and an antenna feedback control loop; (2) In the antenna feedback control loop, the instantaneous initial coordinates, attitudes and radiation source positions of the receiver's multiple antennas are used to calculate and determine the beamforming parameters of each array antenna so that the beams of the multiple antennas are all pointed to the radiation source of the non-cooperative spread spectrum signal; Specifically, the spacecraft starts moving from a position with known coordinates at time t0. At this time, the initial positions of the two array antennas are P1(t0) and P2(t0), respectively. The position of the non-cooperative communication satellite is calculated by orbital position as P s (t0), which is input into the antenna feedback control loop, thereby calculating the space vector P of the non-cooperative communication satellite relative to the two antennas s (t0)-P1(t0) and P s (t0)-P2(t0); Combined with the instantaneous three-axis attitude value obtained by the current aircraft through inertial navigation means and the installation attitude of the two array antennas on the body, the vectors r1(t0) and r2(t0) of the non-cooperative communication satellite relative to the axial direction of the two antennas are calculated, and the beamforming parameters of the two array antennas are controlled on this basis so that the beams of the two antennas are both pointed to the non-cooperative communication satellite; (3) Input the multi-antenna received signal into the signal filter, and perform down-conversion and bandpass filtering on the non-cooperative spread spectrum signal received by each array antenna based on the known information of the frequency point, bandwidth and modulation mode of the non-cooperative spread spectrum signal, retain the multi-channel sampling signal within the frequency band where the non-cooperative signal is located, and input it into the frequency detector; Specifically, the two antenna receiving signals are input into the signal filter, and the predicted communication satellite non-cooperative spread spectrum signal frequency point f s (t0), bandwidth and modulation style, down-convert and bandpass filter the non-cooperative spread spectrum signals received by the two array antennas, retain the multi-channel sampling signals within the frequency band where the non-cooperative signals are located, and input them into the frequency detector; (4) The frequency detector uses the instantaneous initial coordinates, attitudes and radiation source positions of the multiple antennas of the receiver to calculate the frequency difference between the non-cooperative spread spectrum signals received by the multiple antennas, and then fine-tunes the frequency of the multi-channel sampling signal to keep it consistent, and inputs it into the direct sampling signal tracking loop; Specifically, the frequency detector uses the instantaneous coordinates P1(t0) and P2(t0) of the two antennas of the receiver, the position of the non-cooperative communication satellite P s (t0), as well as the velocity and attitude of the aircraft at time t0, the instantaneous relative velocity difference dv(t0) between the two array antennas and the non-cooperative communication satellite is calculated: Where v1(t0) and v2(t0) are the movement speeds of the two antennas corresponding to the aircraft's movement speed and attitude; According to the signal frequency f s (t0) to obtain the instantaneous frequency difference df(t0) between the signals: Where c is the speed of light; Fine-tune the sampling signal frequencies of other channels to keep the multi-channel sampling signal frequencies consistent, and input them into the direct sampling signal tracking loop; (5) The direct sampling signal tracking loop takes one of the input multi-channel sampling signals as the reference, denoted as s1; performs secondary down-conversion on the other signals, with the frequency adjustment value being f0. The down-converted signals are denoted as s2 to s n ; Generate a carrier with frequency f0 and adjustable phase locally as the local carrier loop reference frequency signal pair s2~s n Modulation mixing is performed, and correlation processing is performed with s1 to obtain the carrier phase difference with s1 respectively; at the same time, the lead-lag phase detector is used to compare s1 with the mixed s2~s n Perform correlation processing to obtain the time delay difference of multi-channel sampling signals as output; (6) The receiver uses the output to calculate and update its own position, and outputs it to the antenna feedback control loop and frequency detector; and repeats steps (2) to (6).

2. A non-cooperative spread spectrum signal receiver based on multiple antennas, characterized in that: It includes a receiver loop and at least two array antennas, wherein the array antennas have beam forming and pointing capabilities, and the receiver loop is composed of a signal filter assisted by predicted parameters, a frequency detector, a direct sampling signal tracking loop, and an antenna feedback control loop. The antenna feedback control loop uses the instantaneous initial coordinates, attitudes and radiation source positions of the receiver's multiple antennas to calculate and determine the beamforming parameters of each array antenna, so that the beams of the multiple antennas are all pointed to the radiation source of the non-cooperative spread spectrum signal. Specifically, the spacecraft starts moving from a position with known coordinates at time t0. At this time, the initial positions of the two array antennas are P1(t0) and P2(t0), respectively. The position of the non-cooperative communication satellite is calculated by orbital position as P s (t0), which is input into the antenna feedback control loop, thereby calculating the space vector P of the non-cooperative communication satellite relative to the two antennas s (t0)-P1(t0) and P s (t0)-P2(t0); Combined with the instantaneous three-axis attitude value obtained by the current aircraft through inertial navigation means and the installation attitude of the two array antennas on the body, the vectors r1(t0) and r2(t0) of the non-cooperative communication satellite relative to the axial direction of the two antennas are calculated, and the beamforming parameters of the two array antennas are controlled on this basis so that the beams of the two antennas are both pointed to the non-cooperative communication satellite; The signal filter receives the multi-antenna receiving signal input from the outside, and performs down-conversion and bandpass filtering on the non-cooperative spread spectrum signal received by each array antenna through the pre-known information of the frequency point, bandwidth and modulation mode of the non-cooperative spread spectrum signal, retains the multi-channel sampling signal in the frequency band where the non-cooperative signal is located, and inputs it to the frequency detector; Specifically, the two antenna receiving signals are input into the signal filter, and the predicted communication satellite non-cooperative spread spectrum signal frequency point f s (t0), bandwidth and modulation style, down-convert and bandpass filter the non-cooperative spread spectrum signals received by the two array antennas, retain the multi-channel sampling signals within the frequency band where the non-cooperative signals are located, and input them into the frequency detector; The frequency detector uses the instantaneous initial coordinates, attitudes and radiation source positions of the receiver's multiple antennas to calculate the frequency difference between the non-cooperative spread spectrum signals received by the multiple antennas, and then fine-tunes the frequency of the multi-channel sampling signal to keep it consistent, and inputs it into the direct sampling signal tracking loop; Specifically, the frequency detector uses the instantaneous coordinates P1(t0) and P2(t0) of the two antennas of the receiver, the position of the non-cooperative communication satellite P s (t0), as well as the velocity and attitude of the aircraft at time t0, the instantaneous relative velocity difference dv(t0) between the two array antennas and the non-cooperative communication satellite is calculated: Where v1(t0) and v2(t0) are the movement speeds of the two antennas corresponding to the aircraft's movement speed and attitude; According to the signal frequency f s (t0) to obtain the instantaneous frequency difference df(t0) between the signals: Where c is the speed of light; Fine-tune the sampling signal frequencies of other channels to keep the multi-channel sampling signal frequencies consistent, and input them into the direct sampling signal tracking loop; The direct sampling signal tracking loop takes one of the input multi-channel sampling signals as the reference, denoted as s1; performs secondary down-conversion on the other signals, with the frequency adjustment value being f0, and the down-converted signals are denoted as s2~s n ; Generate a carrier with frequency f0 and adjustable phase locally as the local carrier loop reference frequency signal pair s2~s n Modulation mixing is performed, and correlation processing is performed with s1 to obtain the carrier phase difference with s1 respectively; at the same time, the lead-lag phase detector is used to compare s1 with the mixed s2~s n Perform correlation processing to obtain the time delay difference of multi-channel sampling signals as output; The receiver uses the output to calculate and update its own position and outputs it to the antenna feedback control loop and frequency detector.

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