CN117040564A - Communication and distance measurement integrated method based on template reconstruction - Google Patents

Abstract

The invention discloses a communication and ranging integrated method based on template reconstruction, and belongs to the field of communication signal processing. The implementation method of the invention comprises the following steps: transmitting a spread spectrum signal having a "pilot+data" frame structure; the receiving end obtains a baseband signal after being processed by the radio frequency front end; capturing the received signal by using pilot frequency information in the signal and adopting a matched filtering method to obtain the relative time delay of the received signal and a local pilot frequency sequence, and initially positioning the arrival time of the received signal; the received signal and the three local pseudo code sequences of leading, instant and lagging generated by the receiving end respectively carry out integral clearing operation,the integration result passes through a phase discriminator and a loop filter to obtain a control word increment of a code NCO; updating the phase of the local pseudo code sequence by code table addressing, and reconstructing the length of the pilot frequency by a template _h Bit increase to L _frm Bits; a higher gain is introduced for the loop integral clean-up operation by increasing the pilot length. The invention has the advantages of communication and ranging integration, emission energy saving, high distance measurement precision and the like.

Description

An integrated method of communication ranging based on template reconstruction

Technical field

The invention relates to an integrated communication ranging method based on template reconstruction, and belongs to the field of communication signal processing.

Background technique

As one of the important components in the field of satellite communications, navigation and positioning technology can achieve high-precision ranging and speed measurement for users, and then implement precise positioning. Commonly used ranging methods generally include pulse ranging, sidetone ranging, and pseudo-code ranging. In the field of satellite measurement and control, the advantages of pseudo-code ranging are very prominent. The pseudo-random code can simultaneously improve the ranging distance and measurement accuracy with its inherent long period and cross-correlation characteristics, and the use of code division multiple access technology can achieve multiple The target is measured and controlled at the same time. In addition, this ranging method also has the characteristics of strong anti-interference ability and low interception probability. It has become the development direction of my country's new generation measurement and control system.

Initially, pseudo-code ranging was generally implemented through Direct Sequence Spread Spectrum (DSSS) signals. However, when the communication data throughput is the same, using DSSS signals to implement pseudo-code ranging will cause an increase in transmission bandwidth. Large and reduced frequency band utilization. The existing satellite communication frame structure generally requires pilots and communication data. Only the pilot part is used as known pseudo-code information to achieve functions such as synchronization and ranging of received signals, which has a high frequency band utilization rate; however, for this When designing the specific parameters of the frame structure, if the pilot is too long, it will cause a waste of time and frequency resources, and if its length is too short, it will lead to a decrease in synchronization and ranging performance under the same conditions. Therefore, it is of great significance to develop a pseudo-code ranging algorithm with high transmission efficiency and high measurement accuracy under low transmit power.

Contents of the invention

The following technical defects exist in the existing pseudo-code ranging methods: (1): Using DSSS signals to implement pseudo-code ranging will cause problems such as increased transmission bandwidth and low frequency band utilization; (2): Using pilot plus The frame structure of communication data to achieve pseudo-code ranging will suffer from the problems of wasting time and frequency resources and reducing ranging performance caused by too long or too short pilots. The main purpose of the present invention is to provide an integrated communication ranging method based on template reconstruction. While transmitting continuous data, the transmitting end transmits discontinuous pilots as known pseudocode sequences, and the receiving end is locked in digital delay. The template reconstruction module is added to the loop (DigitalDelay Locked Loop, DDLL) to improve the synchronization and measurement performance degradation problems caused by sparse pilots; based on the template reconstruction, the integration of communication and ranging is realized without affecting the communication function and communication rate. to achieve high-precision distance measurement. The invention has the advantages of integrated communication and ranging, saving transmission energy, and high accuracy of communication and ranging.

The object of the present invention is achieved through the following technical solutions.

The invention discloses an integrated communication ranging method based on template reconstruction, which includes the following steps:

Step 1. Send a spread spectrum signal with the following frame structure. The frame structure is: the entire transmission frame is L _frm symbols long, in which the pilot is a pseudo-random sequence with a length of L _h symbols, followed by data to be transmitted with a length of (L _frm - L _h ) symbols. While transmitting continuous data, only non-continuous pilots with a length of _Lh symbols are transmitted as known pseudo-code sequences for time synchronization and distance measurement, thereby saving transmission energy. Compared with the Direct Sequence Spread Spectrum (DSSS) communication system, each frame under this frame structure is equivalent to a symbol in the DSSS signal, and each bit in the frame is regarded as a spreading code.

Step 2: Receive the spread spectrum signal transmitted in step 1, and process the received spread spectrum signal through the radio frequency front end to obtain the baseband signal x(t).

The time domain expression of the baseband signal x(t) is:

Among them, s(t) represents the effective information component in the received signal, and the amplitude is represented by A; T _b represents the duration of a symbol, τ represents the unknown transmission delay; n(t) represents the Gaussian power spectrum of N ₀ White noise; N _frm represents the total number of frames transmitted, n _frm represents the frame number of the current transmission frame; T _frm represents the frame period, expressed as T _frm = T _b × L _frm ; c (k) represents the k-th bit in a frame The data value of , the value range is c(k)={-1,1}; g(t) is the gate function defined according to the following formula (2):

g(t)=u(t)-u(tT _b ) (2)

Among them, u(t) represents the step function. According to formula (2), g(t-kT _b -(n _frm -1)T _frm -τ) in formula (1) is expanded to:

g(t-kT _b -(n _frm -1)T _frm -τ)=u(t-kT _b -(n _frm -1)T _frm -τ)-u(t-(k+1)T _b - (n _frm -1)T _frm -τ)(3)

Combined with the frame structure of the sparse pilots of the transmitted signal in step 1, equation (1) is further expressed as:

Among them, c ₁ (k ₁ ) represents a pseudo-random sequence of length L _h bits located at the frame header; c ₂ (k ₂ ) represents a data signal of (L _frm -L _h ) bits; h ₁ (t-kT _b - (n _frm -1)T _frm -τ) represents the time domain waveform of the frame header, h ₂ (t-kT _b -(n _frm -1)T _frm -τ) represents the time domain waveform of the data domain.

Step 3. The receiving end samples the baseband signal received in Step 2 to implement analog-to-digital conversion. It uses the pilot information in the signal and uses the matched filtering method to capture the converted received signal to obtain the received signal and the local pilot sequence. The relative delay is used to initially locate the arrival time of the received signal based on the relative delay. At the same time, the relative delay also provides a priori information for subsequent tracking of the template reconstruction of the first frame signal.

The baseband signal x(t) is sampled to obtain the digital signal x(n). The local pilot sequence is used to capture the digital signal x(n). According to equation (5), the peak point of the relevant operation is found through the matched filter algorithm:

Among them, x represents the received signal, y represents the local pilot sequence with a length of L _h bits, n represents the relative delay between the received signal and the local pilot sequence, and z(n) represents the local pilot sequence and the received signal under the current delay. related results. When the pilot part of the received signal is completely aligned with the local pilot sequence, z(n) reaches the maximum value, and n at this time is the estimate of the arrival time of the received signal. Use n to perform preliminary compensation for the unknown transmission delay τ in equation (4), and initially locate the arrival time of the received signal based on the relative delay. At the same time, the relative delay is also a template for the subsequent tracking of the first frame signal. Reconstruction provides a priori information.

Step 4: Track the received signal captured in Step 3. The received signal is integrated and cleared with the three-way local pseudo code sequence generated by the receiving end: the lead, the immediate, and the lag. The integration result passes through the phase detector and loop filter. Get the control word increment of the code NCO.

The digital delay locked loop DDLL generates three local pseudo-code sequences at the receiving end: leading, immediate, and lagging. The pseudo-code sequences of the leading and lagging branches are respectively different from the immediate branch by d symbols. The three-way local pseudo-code sequences are respectively different from those of the immediate branch. The received signal performs a correlation operation with time T _h , T _h = T _b × L _h , where: L _h and _Th are both the results after template reconstruction, and three integral clearing results are obtained. Among the three integral clearing results, The integral clearing result P of the immediate branch is the largest, the result E of the leading branch and the result L of the lagging branch are small and equal.

Input the correlation results E and L of the leading branch and lagging branch into the phase detection module. According to formula (6), use the non-coherent leading minus lag power phase detector to detect the time difference between the received signal and the local immediate branch sequence:

The phase identification results are normalized and processed with lag, and then input to the loop filter module. The loop filter adopts the second-order Jaffe-Rechtin filter algorithm:

in, is the phase estimate of the kth synchronization code, ω _nc is the natural angular frequency of the loop filter, satisfying ω _nc = 1.89B _L , B _L is the loop bandwidth, K _d and K are the phase detector and loop filter respectively gain coefficient of the converter.

The loop filter finally generates the control word increment output to the code NCO, which is expressed as:

Among them, ΔF _k+1 is the frequency control word increment output by the filter. When the local frame header sequence is updated, the frequency word increment is added to the code loop initial frequency control word F _ini to obtain the code rate control word, F _ini Expressed as:

K _f is the conversion coefficient of the frequency control word, expressed as:

Table_depth represents the depth of the code table, dividing a symbol into 2 ^Table_depth parts.

Step 5: According to the control word of the code NCO obtained in step 4, update the phase of the local pseudo code sequence through code table addressing, and increase the length of the pilot from L _h bits to L _frm bits through template reconstruction. By increasing the pilot length, it brings higher gain to the loop integral clearing operation, thereby improving the signal-to-noise ratio and improving the problem of synchronization and measurement performance degradation caused by the sparse pilot of the transmitted signal.

After the loop filter output frequency word changes by ΔF _k+1 , the code NCO updates the phase of the local pseudo code sequence through code table addressing, where the initial phase value of each frame addressing is Expressed as:

in, Represents the estimated number of sampling points of the current frame during the code loop tracking process, calculated from ΔF _k+1 ; % represents the remainder operation:

Before the received signal passes through the code NCO, it needs to go through the template reconstruction module to realize the template reconstruction of the local pseudocode sequence. The implementation method of the template reconstruction of the local pseudocode sequence is as follows:

By each frame signal and ΔF _k information to obtain the phase of each sampling point of the current transmission frame/>

Where n represents the serial number of the current sampling point, Indicates the phase information corresponding to the current sampling point.

Using the phase information of each sampling point of the current frame, the receiving end estimates the symbol information corresponding to the best sampling point of each symbol through linear interpolation. If the phase information of the sampling point satisfies:

Then determine the sampling point Can be used to represent the i-th symbol.

Phase information based on the above sampling points and their corresponding symbolic information. The corresponding symbol information at the phase (i+0.5)×2 ^Table_depth is obtained through linear interpolation and the original symbol information c(i) is demodulated through hard decision.

According to equation (15) and through linear interpolation, the optimal sampling value of each symbol in the entire transmission frame is calculated, and c(i) is placed in the signal generation module as a new pilot to increase the length of the original sparse pilot. The length of the pilot is increased from L _h bits to L _frm bits through template reconstruction. By increasing the pilot length, it brings higher gain to the loop integral clearing operation, thereby improving the signal-to-noise ratio and improving the problem of synchronization and measurement performance degradation caused by sparse pilots in the transmitted signal.

Step 6: Repeat steps 4 to 5 until the three-way integral clearing result satisfies that the integral results of the leading branch and the lagging branch are equal and less than the integral result of the immediate branch, the digital delay locked loop DDLL loop is stable, and the instantaneous The local sequence of the branch is completely aligned with the phase of the received signal, so that the value of the phase identification result δ _cp is infinitely close to 0, realizing the integration of communication and ranging. The root mean square error (RMSE) of the phase detection result δ _cp is used to measure the tracking performance and the accuracy of distance measurement. The signal-to-noise ratio gain is brought about by template reconstruction, so the frame header template reconstruction reduces the The RMSE of the phase detection result improves tracking performance and distance measurement accuracy.

Beneficial effects:

1. The present invention discloses an integrated communication ranging method based on template reconstruction. A template reconstruction module is added to the traditional delay locked loop DDLL to recover the entire frame signal through the original small amount of pilot information, completing the Template reconstruction of the local pseudo-code sequence uses the reconstructed local pseudo-code sequence to track the received signal to improve the signal-to-noise ratio, thereby improving the accuracy of time synchronization and distance measurement.

2. The present invention discloses an integrated communication ranging method based on template reconstruction, which saves the transmission of the transmitted signal by adding discontinuous pilots as known pseudo code sequences in the transmitted signal for time synchronization and distance measurement. power, and also has high information transmission efficiency. At the same time, it can complete high-precision distance measurement without affecting the communication function and communication rate, and realize the integration of communication and ranging.

Description of the drawings

Figure 1 is a schematic flow chart of an integrated communication ranging method based on template reconstruction according to the present invention;

Figure 2 is a DDLL loop structure diagram with a template reconstruction module added according to the present invention;

Figure 3(a) is the result of three-way integral clearing in DDLL with template reconstruction module added in a low signal-to-noise ratio environment; Figure 3(b) is the comparison of the results of three-way integral clearing in DDLL using only the original pilot. picture;

Figure 4 is a comparison chart of the RMSE performance curve of the DDLL loop phase identification error of the added template reconstruction according to the present invention and the DDLL loop phase identification error under different pilot lengths.

Detailed ways

In order to better explain the purpose, implementation scheme and beneficial effects of the present invention, the content of the present invention will be further introduced below in conjunction with the description of the drawings and specific parameter settings.

As shown in Figure 1, the overall flow chart of the integrated communication ranging method based on template reconstruction proposed in this embodiment is shown in Figure 1. The delay locked loop structure of adding the template reconstruction module is shown in Figure 2.

This embodiment discloses an integrated communication ranging method based on template reconstruction. The specific implementation steps are as follows:

Step 1. Send a spread spectrum signal with the following frame structure. The frame structure is: the entire transmission frame length L _frm is 8192 symbols, in which the pilot is a pseudo-random sequence with a length of L _h =128 symbols, followed by data to be transmitted with a length of 8064 symbols. Compared with the general Direct Sequence Spread Spectrum (DSSS) communication system, each frame under this frame structure is equivalent to a symbol in the DSSS signal, and each bit in the frame is regarded as a spreading code.

Step 2: Receive the spread spectrum signal transmitted in step 1, and process the received spread spectrum signal through the radio frequency front end to obtain the baseband signal x(t).

The time domain expression of the baseband signal x(t) is:

Among them, s(t) represents the effective information component in the received signal, the amplitude A=1; the duration of one symbol T _b =0.4020ns, τ represents the unknown transmission delay; n(t) represents the power spectrum as N ₀ Gaussian white noise, where the signal-to-noise ratio satisfies E _b /N ₀ =-10dB; the total number of transmitted frames N _frm =3000, n _frm represents the frame number of the current transmission frame; the frame period can be expressed as T _frm =T _b × L _frm = 3.2932μs; c(k) represents the data value of the k-th bit in a frame, and the value range is c(k) = {-1,1}; g(t) is the gate function defined as follows :

g(t)=u(t)-u(tT _b ) (17)

Among them, u(t) represents the step function. According to formula (2), g(t-kT _b -(n _frm -1)T _frm -τ) in formula (1) can be expanded to:

g(t-kT _b -(n _frm -1)T _frm -τ)=u(t-kT _b -(n _frm -1)T _frm -τ)-u(t-(k+1)T _b - (n _frm -1)T _frm -τ)(18)

Combined with the frame structure of sparse pilots in the transmitted signal mentioned in step 1, equation (14) can be further expressed as:

Among them, c ₁ (k ₁ ) represents a pseudo-random sequence with a length of L _h = 128 bits located at the frame header; c ₂ (k ₂ ) represents an 8064-bit data signal; h ₁ (t-kT _b -(n _frm - 1)T _frm -τ) represents the time domain waveform of the frame header, h ₂ (t-kT _b -(n _frm -1)T _frm -τ) represents the time domain waveform of the data domain.

Step 3. The receiving end samples the baseband signal received in Step 2 to implement analog-to-digital conversion. It uses the pilot information in the signal and uses the matched filtering method to capture the converted received signal to obtain the received signal and the local pilot sequence. The relative delay is used to initially locate the arrival time of the received signal based on the relative delay. At the same time, the relative delay also provides a priori information for subsequent tracking of the template reconstruction of the first frame signal.

The baseband signal x(t) is sampled to obtain the digital signal x(n). The local pilot sequence is used to capture the digital signal x(n). According to equation (20), the peak point of the relevant operation is found through the matched filter algorithm:

Among them, x represents the received signal, y represents the local pilot sequence with a length of 128 bits, n represents the relative delay between the received signal and the local pilot sequence, and z(n) represents the relationship between the local frame header sequence and the received signal under the current delay. Related results. When the frame header part of the received signal is completely aligned with the local frame header sequence, z(n) reaches the maximum value, and n at this time is the estimate of the arrival time of the received signal. Use n to initially compensate the unknown transmission delay τ in equation (4), and the subsequent signal enters the pseudo code phase tracking module.

Step 4: Track the received signal captured in Step 3. The received signal is integrated and cleared with the three-way local pseudo code sequence generated by the receiving end: the lead, the immediate, and the lag. The integration result passes through the phase detector and loop filter. Get the control word increment of the code NCO.

The digital delay locked loop DDLL generates three local pseudo-code sequences at the receiving end: leading, immediate, and lagging. The sequences of the leading and lagging branches differ from the immediate branch by d=0.5 symbols respectively. The three-way local pseudo-code sequences are respectively different from those of the immediate branch. The received signal performs a correlation operation with time T _h . Here T _h refers to the result after template reconstruction, which is the duration of the entire frame 3.2932 μs. Three integral clearing results are obtained. Among the three integral clearing results, the instant The integral clearing result P of the branch is the largest, the result E of the leading branch and the result L of the lagging branch are small and equal.

Input the correlation results E and L of the leading branch and lagging branch into the phase detection module. According to formula (21), use the non-coherent leading minus lag power phase detector to detect the time difference between the received signal and the local immediate branch sequence:

The phase identification results are normalized and processed with lag, and then input to the loop filter module. The loop filter adopts the second-order Jaffe-Rechtin filter algorithm:

in, is the phase estimate of the kth synchronization code, the loop gain K _d /K=1, ω _nc is the natural angular frequency of the loop filter, satisfying ω _nc =1.89B _L =2.268, phase detector and loop filter gain coefficient.

The loop filter finally generates the control word output to the code NCO, which is expressed as:

Among them, ΔF _k+1 is the frequency control word increment output by the filter, and the code table depth Table_depth=32. When the local pseudo code sequence is updated, the frequency word increment is the same as the code loop initial frequency control word F _ini =2.1369×10 ⁹ is added to obtain the code rate control word; the conversion coefficient of the frequency control word K _f =7037.

Step 5: According to the control word of the code NCO obtained in step 4, update the phase of the local pseudo code sequence through code table addressing, and increase the length of the pilot from 128 bits to 8192 bits through template reconstruction. The increase in pilot length can bring higher gain to the loop integral clearing operation to improve the signal-to-noise ratio, and improve the problem of synchronization and measurement performance degradation caused by the sparse pilot of the transmitted signal.

After the loop filter output frequency word changes by ΔF _k+1 , the code NCO updates the phase of the local pseudo code sequence through code table addressing, where the initial phase value of each frame addressing is It can be expressed as:

in, Represents the estimated number of sampling points of the current frame during the code loop tracking process, which can be calculated from ΔF _k+1 ; % represents the remainder operation:

Before the received signal passes through the code NCO, it needs to go through the template reconstruction module to complete the template reconstruction of the local frame header sequence. The specific operations are as follows:

By each frame signal and ΔF _k information can obtain the phase of each sampling point of the current transmission frame/>

Where n represents the serial number of the current sampling point, Indicates the phase information corresponding to the current sampling point.

Using the phase information of each sampling point of the current frame, the receiving end estimates the symbol information corresponding to the best sampling point of each symbol through linear interpolation. If the phase information of the sampling point satisfies:

It is considered that the sampling point Can be used to represent the i-th symbol.

Phase information based on the above sampling points and their corresponding symbolic information. The corresponding symbol information c(i) at phase (i+0.5)×2 ³² is obtained through linear interpolation.

According to equation (28) and through linear interpolation, the optimal sampling value of each symbol in the entire transmission frame is calculated, and c(i) is placed in the signal generation module as a new pilot to increase the length of the original sparse pilot. The pilot length is increased from 128 bits to 8192 bits through template reconstruction. The increase in pilot length can bring higher gain to the loop integral clearing operation to improve the signal-to-noise ratio, and improve the problem of synchronization and measurement performance degradation caused by sparse pilots in the transmitted signal.

Step 6: Repeat steps 4 to 5 until the three-way integral clearing result satisfies that the integral results of the leading branch and the lagging branch are equal and less than the integral result of the immediate branch, the digital delay locked loop DDLL loop is stable, and the instantaneous The local sequence of the branch is completely aligned with the phase of the received signal, so that the value of the phase identification result δ _cp is infinitely close to 0, realizing the integration of communication and ranging. The root mean square error (RMSE) of the phase detection result δ _cp is used to measure the tracking performance and the accuracy of distance measurement. The signal-to-noise ratio gain is brought about by template reconstruction, so the frame header template reconstruction reduces the The RMSE of the phase detection result improves tracking performance and distance measurement accuracy.

Figure 3 describes the comparison of the integration clearing results of the three-way signal of the delay locked loop with or without adding the template reconstruction module under the same transmit signal and signal-to-noise ratio. It can be seen from the figure that under the current lower signal-to-noise ratio , pseudo-code phase tracking only through the 128-bit local pilot can no longer distinguish the three-way integrated signals, and the code loop cannot work normally at this time; after adding the template reconstruction module, the signal-to-noise ratio is greatly improved, and after the loop is stabilized, the lead The correlation values of the branch and the delayed branch are basically equal and about half of the correlation value of the immediate branch, indicating that the value of the phase identification result δ _cp at this time is basically close to 0.

Figure 4 describes the RMSE curves of the code loop phase detection results under different states, respectively, the pilot length is 128 bits (no template reconstruction is added), the pilot length is 256 bits (no template reconstruction is added), and the pilot length is 8192 bits (without template reconstruction), the pilot length is 128 bits (with template reconstruction added), and the lower bound of the delay locked loop tracking accuracy under the corresponding signal-to-noise ratio. It can be seen from the figure that the longer the length of the known pilot sequence, the smaller the root mean square error of the code loop phase identification result, and the better the tracking performance; and, the loop after template reconstruction of the 128-bit local pilot sequence is The track tracking performance is basically the same as that of directly sending an 8192-bit known sequence, and is very close to the lower bound of code loop tracking accuracy; under the current parameters, the root mean square error is less than 10ps when the signal-to-noise ratio CNR>88dB, and the distance accuracy at this time is calculated Can reach centimeter level.

The above specific description further explains the purpose, technical solutions and beneficial effects of the invention in detail. It should be understood that the above are only specific embodiments of the invention and are not intended to limit the protection of the invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention shall be included in the protection scope of the present invention.

Claims (5)

1. A communication distance measurement integration method based on template reconstruction is characterized in that: comprises the following steps of the method,

step one, transmitting a spread spectrum signal with the following frame structure; the frame structure is as follows: transmission frame overall length L _frm Symbols, where the pilot is of length L _h A pseudo-random sequence of symbols followed by a sequence of length (L _frm -L _h ) Data to be transmitted of the individual symbols; by transmitting only a length L while transmitting continuous data _h The discontinuous pilot frequency of each symbol is used as the known pseudo code sequence for time synchronization and distance measurement, so that the saving is achievedEmitting energy; each frame in the frame structure corresponds to one code element in the DSSS signal, and each bit in the frame is regarded as a spread spectrum code;

step two, receiving the spread spectrum signal transmitted in the step one, and processing the received spread spectrum signal through a radio frequency front end to obtain a baseband signal x (t);

step three, the receiving terminal samples the baseband signal received in the step two to realize analog-to-digital conversion, captures the converted received signal by using pilot frequency information in the signal and adopting a matched filtering method to obtain the relative time delay of the received signal and a local pilot frequency sequence, initially positions the arrival time of the received signal according to the relative time delay, and simultaneously provides prior information for the template reconstruction of the follow-up first frame signal;

tracking the received signal captured in the step three, and respectively carrying out integral clearing operation on the received signal and three local pseudo code sequences of leading, immediate and lagging generated by a receiving end, wherein an integral result passes through a phase discriminator and a loop filter to obtain a control word increment of a code NCO;

step five, according to the control word of the code NCO obtained in step four, updating the phase of the local pseudo code sequence in a code table addressing mode, and reconstructing the template to ensure that the length of the pilot frequency is L _h Bit increase to L _frm Bits; the pilot frequency length is increased to bring higher gain for loop integral clearing operation, so that the signal-to-noise ratio is improved;

step six: repeating the steps four to five until the three-way integral clearing result meets the condition that the integral result of the leading branch and the lagging branch is equal to or smaller than the integral result of the instant branch, realizing the DDLL loop stabilization of the digital delay locking loop, and completely aligning the local sequence of the instant branch with the phase of the received signal at the moment to ensure the phase discrimination result delta _cp The value of (2) is infinitely close to 0, so that the integration of communication and ranging is realized; using phase discrimination result delta _cp The tracking performance and the distance measurement accuracy are measured by the Root Mean Square Error (RMSE), and the gain of the signal to noise ratio is brought by the template reconstruction, so that the RMSE of the phase discrimination result is reduced by the frame header template reconstruction, and the tracking performance and the distance measurement accuracy are improved.

2. The integrated communication ranging method based on template reconstruction as claimed in claim 1, wherein: in the second step, the second step is to carry out the process,

the time domain expression of the baseband signal x (t) is:

wherein s (t) represents the effective information component in the received signal, and the amplitude is represented by A; t (T) _b Representing the duration of one symbol, τ represents an unknown transmission delay; n (t) represents a power spectrum of N ₀ Is white gaussian noise; n (N) _frm Representing the total number of frames transmitted, n _frm A frame number representing a current transmission frame; t (T) _frm Representing a frame period, denoted T _frm ＝T _b ×L _frm The method comprises the steps of carrying out a first treatment on the surface of the c (k) represents the data value of the kth bit in one frame, and the value range is c (k) = { -1,1}; g (t) is a gate function defined by the following formula (2):

g(t)＝u(t)-u(t-T _b ) (2)

wherein u (t) represents a step function, g (t-kT) in formula (1) according to formula (2) _b -(n _frm -1)T _frm - τ) is expanded to:

g(t-kT _b -(n _frm -1)T _frm -τ)＝u(t-kT _b -(n _frm -1)T _frm -τ)-u(t-(k+1)T _b -(n _frm -1)T _frm -τ) (3)

in combination with the frame structure of the sparse pilot that the transmission signal in step one has, formula (1) is further expressed as:

wherein c ₁ (k ₁ ) Indicating that the length at the frame head is L _h A pseudo-random sequence of bits; c ₂ (k ₂ ) Representation (L) _frm -L _h ) Number of bitsA data signal; h is a ₁ (t-kT _b -(n _frm -1)T _frm - τ) represents the time domain waveform of the frame header, h ₂ (t-kT _b -(n _frm -1)T _frm - τ) represents the time domain waveform of the data domain.

3. The integrated communication ranging method based on template reconstruction as claimed in claim 2, wherein: in the third step, the baseband signal x (t) is sampled to obtain a digital signal x (n), the digital signal x (n) is captured by using a local pilot sequence, and a peak point of the correlation operation is found by a matched filtering algorithm according to the formula (5):

wherein x represents a received signal and y represents a length L _h The local pilot sequence of the bit, n represents the relative time delay of the received signal and the local pilot sequence, and z (n) represents the correlation result of the local pilot sequence and the received signal under the current time delay; when the pilot frequency part of the received signal is completely aligned with the local pilot frequency sequence, z (n) reaches the maximum value, and n at the moment is the estimation of the arrival time of the received signal; and (3) carrying out preliminary compensation on the unknown transmission delay tau in the formula (4) by using n, and preliminarily positioning the arrival time of the received signal according to the relative delay, wherein the relative delay also provides prior information for the template reconstruction of the first frame signal which is tracked subsequently.

4. A communication ranging integration method based on template reconstruction as claimed in claim 3, wherein: in the fourth step, the first step is performed,

the DDLL generates three local pseudo code sequences of leading, instant and lagging at the receiving end, wherein the pseudo code sequences of the leading and lagging branches are respectively different from the instant branches by d symbols, and the three local pseudo code sequences are respectively processed with the receiving signal for a time T _h Related operation T of (1) _h ＝T _b ×L _h Wherein: l (L) _h And T _h Are template reconstructionThe result after that, three integral clearing results are obtained, in the three integral clearing results, the integral clearing result P of the instant branch is the largest, and the result E of the leading branch and the result L of the lagging branch are smaller and equal relative to the integral clearing result P;

inputting correlation results E and L of the leading branch and the lagging branch into a phase detection module, and detecting the time difference between a received signal and a local instant branch sequence by using a non-coherent leading-subtracting-lagging power phase detector according to a formula (6):

the phase discrimination result is subjected to normalization processing hysteresis and is input into a loop filter module, and a loop filter adopts a second-order Jaffe-Rechtin filter algorithm:

wherein,is the phase estimate, ω, of the kth synchronization code _nc Is the natural angular frequency of the loop filter and meets omega _nc ＝1.89B _L ，B _L Is the loop bandwidth, K _d And K are gain coefficients of the phase detector and the loop filter, respectively;

the loop filter ultimately produces control word increments that are output to the code NCO, expressed as:

wherein DeltaF _k+1 Is a filter inputThe frequency control word increment is outputted, and when the local frame head sequence is updated, the frequency word increment and the code ring initial frequency control word F _ini Adding to obtain code rate control word F _ini Expressed as:

K _f the conversion coefficient for the frequency control word is expressed as:

wherein Table_depth represents the code Table depth, dividing a symbol into 2 ^Table_depth Parts by weight.

5. The integrated communication ranging method based on template reconstruction as claimed in claim 4, wherein: in the fifth step, the first step is to carry out the process,

output frequency word change amount DeltaF of loop filter _k+1 The code NCO updates the phase of the local pseudo code sequence by means of code table addressing, wherein the initial value of the phase of each frame addressing isExpressed as:

wherein,an estimated value of sampling point number representing the current frame in the code loop tracking process is represented by delta F _k+1 Calculating to obtain; % represents the remainder operation:

before the received signal passes through the code NCO, the received signal needs to go through a template reconstruction module to realize the template reconstruction of the local pseudo code sequence, and the template reconstruction realization method of the local pseudo code sequence is as follows:

by signals of each frameAnd DeltaF _k Phase of each sample point of the information current transmission frame>

Where n represents the sequence number of the current sample point,representing phase information corresponding to a current sampling point;

the receiving end estimates the symbol information corresponding to the optimal sampling point of each symbol by using the phase information of each sampling point of the current frame in a linear interpolation mode, and if the phase information of the sampling points meets the following conditions:

then the sampling point is determinedCan be used to represent the ith symbol;

phase information based on the sampling pointsAnd its divisionSymbol information +.>Obtaining the phase (i+0.5). Times.2 by linear interpolation ^Table_depth Corresponding symbol information is obtained and the original symbol information c (i) is demodulated through hard decision;

calculating an optimal sampling value of each symbol in the whole transmission frame according to the formula (15), and placing c (i) into a signal generation module as a new pilot frequency to increase the length of the original sparse pilot frequency; the length of pilot frequency is reconstructed by template and is formed by L _h Bit increase to L _frm Bits; the pilot frequency length is increased to bring higher gain for loop integral clearing operation, so that the signal to noise ratio is improved, and the problems of synchronization and measurement performance reduction caused by sparse pilot frequency of a transmitted signal are solved.