阅读说明：本技术 一种基于数字信道化的脉内频率编码信号参数测量方法 (Intra-pulse frequency coding signal parameter measurement method based on digital channelization ) 是由 刘国满 高梅国 霍佳雨 董珣 于 2019-09-24 设计创作，主要内容包括：本发明公开了一种基于数字信道化的脉内频率编码信号参数测量方法,能够解决目前对频率编码信号难以进行实时参数测量的问题。具体为：获取雷达回波信号,进行数字信道化处理,并获取每个信道对应信号的瞬时频率信息。对瞬时频率信息进行差分获取瞬时频率差分点,对瞬时频率差分点进行过门限检测得到过门限点。依据过门限点,判断雷达回波信号是否为频率编码信号；若为频率编码信号,则取每个信道中各个脉冲的脉冲宽度,对所有脉冲宽度进行统计分析得到频率编码信号的码元宽度。根据码元宽度和频率跳变点的位置对瞬时频率信息进行划分,得到各码元位置,统计码元数以及码元频率,通过对码元频率排序,得到频率编码序列。(The invention discloses a digital channelization-based intra-pulse frequency coding signal parameter measurement method, which can solve the problem that the real-time parameter measurement of a frequency coding signal is difficult at present. The method specifically comprises the following steps: and acquiring radar echo signals, performing digital channelization processing, and acquiring instantaneous frequency information of signals corresponding to each channel. And carrying out difference on the instantaneous frequency information to obtain an instantaneous frequency difference branch point, and carrying out threshold passing detection on the instantaneous frequency difference branch point to obtain a threshold passing point. Judging whether the radar echo signal is a frequency coding signal or not according to the threshold crossing point; and if the signal is a frequency coding signal, taking the pulse width of each pulse in each channel, and performing statistical analysis on all the pulse widths to obtain the code element width of the frequency coding signal. And dividing instantaneous frequency information according to the code element width and the position of the frequency jump point to obtain each code element position, counting the number of code elements and the frequency of the code elements, and sequencing the frequency of the code elements to obtain a frequency coding sequence.)

1. A method for measuring intra-pulse frequency-coded signal parameters based on digital channelization, comprising:

s1, radar echo signals are obtained, digital channelization is carried out, and instantaneous frequency information of signals corresponding to each channel is obtained;

s2, carrying out difference on the instantaneous frequency information to obtain an instantaneous frequency difference branch point, and carrying out threshold passing detection on the instantaneous frequency difference branch point to obtain a threshold passing point;

s3, judging whether the radar echo signal is a frequency coding signal or not according to the threshold crossing point; if the signal is a frequency-encoded signal, performing S4 and S5;

s4, taking the pulse width of each pulse in each channel, and carrying out statistical analysis on all the pulse widths to obtain the code element width of the frequency coding signal;

s5, dividing the instantaneous frequency information according to the width of the code element and the position of the frequency jumping point to obtain the position of each code element, counting the number of the code elements and the frequency of the code elements, and sequencing the frequency of the code elements to obtain a frequency coding sequence.

2. The method according to claim 1, wherein the differentiating the instantaneous frequency information to obtain an instantaneous frequency difference branch point, and performing threshold detection on the instantaneous frequency difference branch point to obtain a threshold point, which is a frequency trip point, specifically:

differentiating the instantaneous frequency information to obtain a differential result; the instantaneous frequency information comprises instantaneous frequency points at all moments, and the difference result is the difference value between the instantaneous frequency point at each moment and the instantaneous frequency point at the previous moment, namely the instantaneous frequency difference division point at the current moment;

performing threshold-crossing detection on the difference result,

wherein the detection threshold of the nth instantaneous frequency difference branch point is

f_iThe difference result is the average value of the front L values and the rear L values which are separated from the nth instantaneous frequency difference division point; l is a selected length determined by the environmental noise; k is a set self-adaptive threshold coefficient; Δ F is the set threshold offset;

and obtaining an over-threshold point, namely a frequency jump point.

3. The method according to claim 1 or 2, wherein said determining whether the radar echo signal is a frequency encoded signal based on the threshold crossing point is specifically:

judging whether the number of the threshold points is larger than a set threshold value, if so, taking the threshold points as code element hopping positions, determining data segments with set number according to the code element hopping positions, calculating the instantaneous frequency mean value of each data segment, selecting the secondary large value and the secondary small value to be differed to obtain a frequency difference delta F, and if the delta F is larger than the frequency difference threshold T_f2The signal is considered to be a frequency encoded signal.

4. The method of claim 3, wherein the pulse width of each pulse in each channel is taken, and statistical analysis is performed on all pulse widths to obtain a symbol width of the frequency-coded signal, specifically:

counting the pulse width of each pulse in each channel to form a code element width set S;

performing histogram statistics on the set S to obtain n numerical values and corresponding weights thereof in the set S, and rejecting the numerical values of which the weights are 1;

searching the width value of the code element in the histogram from small to large, and stopping searching when the width value of the next code element exceeds 1.5 times of the width value of the current code element to obtain a single-code-element width set;

and calculating the sum of the weights of the adjacent data in the single-time code element width set, and performing weighted average on the two adjacent data with the largest sum of the weights to obtain the code element width of the frequency coding signal.

5. The method of claim 4, wherein the instantaneous frequency information is divided according to the symbol width and the position of the frequency hopping point to obtain each symbol position, count the number of symbols and the symbol frequency, and obtain a frequency-coded sequence by sorting the symbol frequencies, specifically:

taking a starting point of the intra-pulse frequency coding signal and a cut-off point of the signal; wherein the initial value of the starting point is n_sInitial value of cut-off point is n_e；

The position sequence of the threshold passing points is { n₁,n₂,…n_k}；n₁～n_kThe positions of the 1 st to k th threshold-passing points;

symbol width n of the frequency encoded signal_τ；

For the sequence of positions of the threshold crossing points n₁,n₂,…n_kThe following point expansion is performed:

for the sequence of positions of the threshold crossing points n₁,n₂,…n_kThe point-by-point difference is carried out, and the ith difference result is delta n_iIf Δ n is_i＞1.5n_τThen, the ratio K ═ Δ n is calculated_i/n_τ]Wherein]Represents rounding i; for Δ n_iDividing the difference between the two points at equal intervals by K times, recording the division positions, and using Δ n_iFilling the dividing position with the mean value of the two differential points as a new point position;

if the first trip point n₁If the difference from the starting point is greater than 2/3 times of the width of the code element, executing the starting point correction process; the initial point correction process specifically comprises the following steps: taking the initial value of d as 1, judging n₁-(d+1)n_τ≤n_sIf yes, n is added₁-dn_τAs a corrected starting point while retaining n₁-in_τIf not, d is increased by 1, and the initial point correction process is repeated until n is₁-(d+1)n_τ≤n_sIf true;

if the last trip point n_kIf the difference between the code element and the cut-off point is greater than 2/3 times of the code element width, executing the cut-off point correction process; the cut-off point correction process comprises the following steps: taking the initial value of p as 1, judging n_k+(p+1)n_τ≥n_eIf yes, n is added_k+dn_τMaking a corrected cut-off while retaining n_k+in_τ(1 < i < K) thesePoint location, if not, p is increased by 1 by self, and the initial point correction process is repeated until n_k+(p+1)n_τ≥n_eIf true;

after the point location expansion, the position sequence { n) of the frequency jumping points₁,n₂,…n_kConversion to the new sequence n'₁,n'₂,…n'_m}，n₁'～n_m' is the 1 st to m point positions in the new sequence, namely the code element hopping positions; n +1 elements should be in the set of the frequency coding signal with the number of the symbols N, namely m is N + 1; calculating the symbol frequency:

wherein f (k) represents the kth symbol frequency of the intra-pulse frequency-coded signal, k is 1, 2., N, f (i) represents the ith instantaneous frequency measurement of the intra-pulse frequency-coded signal, and Δ N is an empirically set guard width for avoiding frequency instability points generated during inter-symbol hopping;

and after the code element frequency is obtained through calculation, the frequency coding sequence is obtained by sequencing the code element frequency.

Technical Field

The invention relates to the technical field of radar signal reconnaissance, in particular to an intra-pulse frequency coding signal parameter measuring method based on digital channelization.

Background

The wideband intra-pulse frequency coding signal has more and more extensive application in the radar field by virtue of good distance and speed resolution performance, the radar signal form is more and more complicated due to the occurrence of the frequency coding signal, the information contained in the radar pulse cannot be accurately expressed by the conventional pulse parameter measurement, and for the intra-pulse frequency coding signal, the number of code elements, the frequency of the code elements and the coding sequence are important pulse characteristic parameters except for a general pulse description word. At present, relevant researches on measurement of pulse parameters of broadband frequency coding signals mainly use short-time Fourier transform, Weigner distribution and other time frequency analysis methods, and the methods have good performance on intra-pulse characteristic analysis of the frequency coding signals, but have large calculation amount and poor instantaneity, and are difficult to be applied to a radar signal real-time parameter measurement system.

Currently, a real-time parameter measurement method for a wideband intra-pulse frequency coded signal is lacking.

Disclosure of Invention

In view of the above, the present invention provides a method for measuring parameters of an intra-pulse frequency coded signal based on digital channelization, which can solve the problem that it is difficult to perform real-time parameter measurement on a frequency coded signal at present.

In order to achieve the purpose, the technical scheme of the invention comprises the following steps:

and S1, acquiring radar echo signals, performing digital channelization processing, and acquiring instantaneous frequency information of signals corresponding to each channel.

S2, carrying out difference on the instantaneous frequency information to obtain an instantaneous frequency difference branch point, and carrying out threshold passing detection on the instantaneous frequency difference branch point to obtain a threshold passing point.

S3, judging whether the radar echo signal is a frequency coding signal according to the threshold point; if the signal is a frequency-encoded signal, S4 and S5 are performed.

And S4, taking the pulse width of each pulse in each channel, and performing statistical analysis on all the pulse widths to obtain the code element width of the frequency coding signal.

And S5, dividing the instantaneous frequency information according to the width of the code element and the position of the frequency jumping point to obtain the position of each code element, counting the number of the code elements and the frequency of the code elements, and sequencing the frequency of the code elements to obtain a frequency coding sequence.

Further, the instantaneous frequency information is subjected to difference to obtain an instantaneous frequency difference branch point, and the instantaneous frequency difference branch point is subjected to threshold passing detection to obtain a threshold passing point, namely a frequency jump point, specifically:

differentiating the instantaneous frequency information to obtain a differential result; the instantaneous frequency information comprises instantaneous frequency points at all moments, and the difference result is the difference value between the instantaneous frequency point at each moment and the instantaneous frequency point at the previous moment, namely the instantaneous frequency difference division point at the current moment.

The difference result is subjected to threshold-crossing detection,

wherein the detection threshold of the nth instantaneous frequency difference branch point is

f_iThe difference result is the mean value of the front L values and the back L values which are separated from the nth instantaneous frequency difference division point; l is a selected length determined by the environmental noise; k is a set self-adaptive threshold coefficient; Δ F is the set threshold offset.

And obtaining an over-threshold point, namely a frequency jump point.

Further, according to the threshold crossing point, whether the radar echo signal is a frequency coding signal is judged, specifically:

judging whether the number of threshold crossing points is larger than a set threshold value, if so, taking the threshold crossing points as code element hopping positions, determining the data segments with the set number according to the code element hopping positions, calculating the instantaneous frequency mean value of each data segment, selecting the secondary large value and the secondary small value to obtain a frequency difference delta F, and if the delta F is larger than the frequency difference threshold T_f2The signal is considered to be a frequency encoded signal.

Further, the pulse width of each pulse in each channel is taken, and statistical analysis is performed on all the pulse widths to obtain the symbol width of the frequency coding signal, specifically:

and counting the pulse width of each pulse in each channel to form a code element width set S.

And performing histogram statistics on the set S to obtain n numerical values and corresponding weights thereof in the set S, and rejecting the numerical values with the weights being 1.

And searching the symbol width value in the histogram from small to large, and stopping searching when the next symbol width value exceeds 1.5 times of the current symbol width value to obtain a single-symbol-width set.

And calculating the sum of the weights of the adjacent data in the single-time code element width set, and performing weighted average on the two adjacent data with the largest sum of the weights to obtain the code element width of the frequency coding signal.

Further, dividing instantaneous frequency information according to the width of the code element and the position of the frequency jumping point to obtain the position of each code element, counting the number of the code elements and the frequency of the code elements, and sequencing the frequency of the code elements to obtain a frequency coding sequence, which specifically comprises the following steps:

taking a starting point of an intra-pulse frequency coding signal and a cut-off point of the signal; wherein the initial value of the starting point is n_sInitial value of cut-off point is n_e。

The position sequence of the threshold passing points is { n₁,n₂,…n_k}；n₁～n_kThe positions of the 1 st to k th threshold-crossing points.

Symbol width n of frequency encoded signal_τ。

For the sequence of positions of the threshold crossing points n₁,n₂,…n_kThe following point expansion is performed:

for the sequence of positions of the threshold crossing points n₁,n₂,…n_kThe point-by-point difference is carried out, and the ith difference result is delta n_iIf Δ n is_i＞1.5n_τThen, the ratio K ═ Δ n is calculated_i/n_τ]Wherein]Represents rounding i; for Δ n_iDividing the difference between two points at equal intervals by K times, and recording the division positionsBy Δ n_iAnd filling the dividing position with the mean value of the two differential points as a new point position.

If the first trip point n₁If the difference from the starting point is greater than 2/3 times of the width of the code element, executing the starting point correction process; the initial point correction process specifically comprises the following steps: taking the initial value of d as 1, judging n₁-(d+1)n_τ≤n_sIf yes, n is added₁-dn_τAs a corrected starting point while retaining n₁-in_τIf not, d is increased by 1, and the initial point correction process is repeated until n is₁-(d+1)n_τ≤n_sThis is true.

If the last trip point n_kIf the difference between the code element and the cut-off point is greater than 2/3 times of the code element width, executing the cut-off point correction process; the cut-off point correction process is as follows: taking the initial value of p as 1, judging n_k+(p+1)n_τ≥n_eIf yes, n is added_k+dn_τMaking a corrected cut-off while retaining n_k+in_τIf not, p is increased by 1 by itself, and the correction process of the initial point is repeated until n is_k+(p+1)n_τ≥n_eThis is true.

After the point location expansion, the position sequence of frequency jumping points { n }₁,n₂,…n_kConversion to the new sequence n'₁,n'₂,…n'_m}，n₁'～n_m' is the 1 st to m point positions in the new sequence, namely the code element hopping positions; n +1 elements should be in the set of the frequency coding signal with the number of the symbols N, namely m is N + 1; calculating the symbol frequency:

where f (k) denotes the kth symbol frequency of the intra-pulse frequency-coded signal, k is 1,2,.., N, f (i) denotes the ith instantaneous frequency measurement of the intra-pulse frequency-coded signal, and Δ N is an empirically set guard width for avoiding frequency instability points generated during inter-symbol hopping.

And after the code element frequency is obtained through calculation, the frequency coding sequence is obtained by sequencing the code element frequency.

Has the advantages that:

the method for measuring the intra-pulse frequency coding signal parameters based on digital channelization can solve the problem that the real-time parameter measurement of the frequency coding signals is difficult at present, can accurately identify the frequency coding signals of radar echo signals, and can accurately acquire the code element width information of the frequency coding signals.

The method of the invention adopts a mode of combining digital channelized polyphase filtering and phase difference instantaneous frequency measurement to obtain instantaneous frequency information of the signal, adopts an instantaneous frequency difference method to identify the modulation type of the signal, and combines the instantaneous frequency difference detection result and the code element width information of the frequency coding signal to realize the parameter measurement of the frequency coding signal. The invention adopts a digital channelization method to process the frequency coding signal, fully utilizes the pulse width information of each channel in the digital channelization, and accurately acquires the code element width information of the frequency coding signal.

Drawings

FIG. 1 is a flow chart of a method for measuring parameters of an intra-pulse frequency-coded signal based on digital channelization according to the present invention;

FIG. 2 is a schematic diagram of threshold crossing detection in an embodiment of the present invention;

FIG. 3 is a flow chart of signal type identification according to an embodiment of the present invention

Detailed Description

The invention is described in detail below by way of example with reference to the accompanying drawings.

The invention provides a digital channelization-based intra-pulse frequency coding signal parameter measurement method, which adopts a mode of combining digital channelization polyphase filtering and phase difference instantaneous frequency measurement to obtain instantaneous frequency information of a signal, adopts an instantaneous frequency difference method to identify the modulation type of the signal, and combines the instantaneous frequency difference detection result and the code element width information of a frequency coding signal to realize the parameter measurement of the frequency coding signal. The invention adopts a digital channelization method to process the frequency coding signal, fully utilizes the pulse width information of each channel in the digital channelization, and accurately acquires the code element width information of the frequency coding signal.

The method has a flow shown in fig. 1, and specifically comprises the following steps:

and S1, acquiring radar echo signals, performing digital channelization processing, and acquiring instantaneous frequency information of signals corresponding to each channel.

The digital channelizing processing comprises the steps of channelizing, CORDIC amplitude and phase measurement, phase difference frequency measurement, threshold crossing detection, cross-channel combination and the like, and instantaneous frequency information of radar echo signals is obtained.

S2, carrying out difference on the instantaneous frequency information to obtain an instantaneous frequency difference branch point, and carrying out threshold passing detection on the instantaneous frequency difference branch point to obtain a threshold passing point; differentiating the instantaneous frequency information to obtain a differential result; the instantaneous frequency information comprises instantaneous frequency points at all moments, and the difference result is the difference value between the instantaneous frequency point at each moment and the instantaneous frequency point at the previous moment, namely the instantaneous frequency difference division point at the current moment.

Differentiating the instantaneous frequency information, comprising the steps of:

1) n of signal start and stop positions_hDThe point frequency difference is divided by the threshold flag to be 0, n_hDFilter order for a single polyphase branch.

2) And when the instantaneous frequency difference of the nth point is detected, observing whether a threshold point exists in a point delta N-1 before the point. If not, setting the nth point threshold crossing mark to be 1; if the frequency difference value exists, the magnitude of the frequency difference value in the delta N points is compared, the maximum position is set to be 1 through the threshold flag, and the rest are set to be 0.

And carrying out threshold-crossing detection on the difference result, wherein a self-adaptive threshold is adopted in the invention, and the detection threshold of the nth instantaneous frequency difference branch point is as follows:

f_ithe difference result is the mean value of the front L values and the back L values which are separated from the nth instantaneous frequency difference division point; l is noise from the environmentSelecting length determined by sound; k is a set self-adaptive threshold coefficient; Δ F is the set threshold offset. The threshold crossing detection principle is shown in fig. 2.

An over-threshold point is obtained.

S3, judging whether the radar echo signal is a frequency coding signal according to the threshold point; if the signal is a frequency-encoded signal, S4 and S5 are performed.

The judging method specifically comprises the following steps:

and judging whether the number of the threshold points is larger than a set threshold value, if so, determining the radar echo signal bit coded signal, and otherwise, determining the radar echo signal bit coded signal is a non-coded signal.

If the signal is a coding signal, the threshold crossing point is used as the code element hopping position, a set number of data segments are determined by the code element hopping position, the instantaneous frequency mean value of each data segment is calculated, the second largest value and the second smallest value are selected to be differed to obtain a frequency difference delta F, and if the delta F is larger than the frequency difference threshold T_f2The signal is considered to be a frequency encoded signal, otherwise it is a phase encoded signal.

If the signal is a non-coding signal, calculating the average frequency at a plurality of points selected from head to tail, and subtracting the average value of the two frequencies to obtain a frequency difference delta F, comparing the delta F with a frequency difference threshold T_f1If | Δ F | is greater than T_f1And judging the signal to be a linear frequency modulation signal, otherwise, judging the signal to be a single-point frequency signal. The signal type identification process is shown in fig. 3.

S4, taking the pulse width of each pulse in each channel, and carrying out statistical analysis on all the pulse widths to obtain the code element width of the frequency coding signal;

the method specifically comprises the following steps:

(1) and counting the pulse width of each pulse in each channel to form a code element width set S.

(2) And performing histogram statistics on the set S to obtain n numerical values and corresponding weights thereof in the set S, and rejecting the numerical values with the weights being 1.

(3) And searching the symbol width value in the histogram from small to large, and stopping searching when the next symbol width value exceeds 1.5 times of the current symbol width value to obtain a single-symbol-width set.

(4) And calculating the sum of the weights of the adjacent data in the single-time code element width set, and performing weighted average on the two adjacent data with the largest sum of the weights to obtain the code element width of the frequency coding signal.

And S5, dividing the instantaneous frequency information according to the width of the code element and the position of the frequency jumping point to obtain the position of each code element, counting the number of the code elements and the frequency of the code elements, and sequencing the frequency of the code elements to obtain a frequency coding sequence.

The method specifically comprises the following steps:

taking a starting point of an intra-pulse frequency coding signal and a cut-off point of the signal; wherein the initial value of the starting point is n_sInitial value of cut-off point is n_e。

The position sequence of the threshold passing points is { n₁,n₂,…n_k}；n₁～n_kThe positions of the 1 st to k th threshold-crossing points.

Symbol width n of frequency encoded signal_τ。

For the sequence of positions of the threshold crossing points n₁,n₂,…n_kThe following point expansion is performed:

for the sequence of positions of the threshold crossing points n₁,n₂,…n_kThe point-by-point difference is carried out, and the ith difference result is delta n_iIf Δ n is_i＞1.5n_τThen, the ratio K ═ Δ n is calculated_i/n_τ]Wherein]Represents rounding i; for Δ n_iDividing the difference between the two points at equal intervals by K times, recording the division positions, and using Δ n_iAnd filling the dividing position with the mean value of the two differential points as a new point position.

If the first trip point n₁If the difference from the starting point is greater than 2/3 times of the width of the code element, executing the starting point correction process; the initial point correction process specifically comprises the following steps: taking the initial value of d as 1, judging n₁-(d+1)n_τ≤n_sIf yes, n is added₁-dn_τAs a corrected starting point while retaining n₁-in_τIf not, d is increased by 1, and the initial point correction process is repeated until n is₁-(d+1)n_τ≤n_sThis is true.

If the last trip point n_kIf the difference between the code element and the cut-off point is greater than 2/3 times of the code element width, executing the cut-off point correction process; the cut-off point correction process is as follows: taking the initial value of p as 1, judging n_k+(p+1)n_τ≥n_eIf yes, n is added_k+dn_τMaking a corrected cut-off while retaining n_k+in_τIf not, p is increased by 1 by itself, and the correction process of the initial point is repeated until n is_k+(p+1)n_τ≥n_eThis is true.

After the point location expansion, the position sequence of frequency jumping points { n }₁,n₂,…n_kConversion to the new sequence n'₁,n'₂,…n'_m}，n₁'～n_m' is the 1 st to m point positions in the new sequence, namely the code element hopping positions; n +1 elements should be in the set of the frequency coding signal with the number of the symbols N, namely m is N + 1; calculating the symbol frequency:

where f (k) denotes the kth symbol frequency of the intra-pulse frequency-coded signal, k is 1,2,.., N, f (i) denotes the ith instantaneous frequency measurement of the intra-pulse frequency-coded signal, and Δ N is an empirically set guard width for avoiding frequency instability points generated during inter-symbol hopping.

And after the code element frequency is obtained through calculation, the frequency coding sequence is obtained by sequencing the code element frequency.

In summary, the above description is only a preferred embodiment of the present invention, and is not intended to limit the scope of the present invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.