Disclosure of Invention
In order to overcome the defects in the prior art, the embodiment of the invention provides a radio frequency signal processing system based on a microwave broadband instantaneous frequency measurement receiver, which is used for dynamically identifying a frequency shielding response section and recovering an internal frequency evolution path thereof by constructing a joint judging mechanism of a frequency change speed and an amplitude change slope and combining a frequency hopping trend fitting and track connection point reconstruction method so as to solve the problem that a frequency blind area caused by geomagnetic disturbance cannot be demodulated.
In order to achieve the aim, the invention provides the technical scheme that the radio frequency signal processing system based on the microwave broadband instantaneous frequency measurement receiver comprises an identification extraction module, a track reconstruction module, a path switching module and a prediction compensation module;
The identification extraction module is used for dividing the original radio frequency data stream into long-time fragments, extracting a frequency response sequence from each time fragment, and marking the time fragments meeting the conditions as frequency shielding response sections according to the threshold judgment results of the frequency change speed and the amplitude change slope;
The track reconstruction module is used for extracting and judging frequency direction jump trend of a frequency shielding response section in disturbance response description data, constructing a frequency track connection point by fitting a frequency direction trend line, complementing the frequency track connection point into a continuous frequency evolution track by interpolation, and forming a target frequency recovery result;
The path switching module is used for comparing the target frequency recovery result with the original frequency response sequence, replacing the original frequency response sequence in a time segment meeting the condition according to the judging result of the frequency difference sequence, judging whether to execute frequency measurement path switching or not through the shielding compensation mark, and generating a replaced frequency measurement result in the geomagnetic disturbance environment;
The prediction compensation module is used for extracting frequency hopping errors in the alternative frequency measurement result, constructing a frequency disturbance prediction template, generating a frequency shielding prediction window, constructing a predicted frequency track according to the frequency direction change trend, and generating an advanced frequency recovery result.
In a preferred embodiment, the identification extraction module is configured to divide an original radio frequency data stream acquired by the microwave broadband instantaneous frequency measurement receiver into long-time segments, and perform discrete extraction on a frequency response in each time segment;
calculating the frequency change speed and the amplitude change slope of the frequency response sequence extracted from each time segment to be used as quantitative expression of frequency behaviors in the time segment;
Judging whether the frequency change speed is in a preset frequency change speed threshold range in at least three continuous time points, and the amplitude change slope is in a preset amplitude change slope threshold range in at least three corresponding continuous time points, if so, marking the time segment as a frequency gradual change response section, otherwise, skipping the current time segment, and continuing to process the next time segment;
judging whether the center frequency of the frequency gradual change response section is smaller than a preset center frequency threshold value, judging whether the duration of the frequency gradual change response section is larger than a preset duration threshold value, if so, marking the frequency gradual change response section as a frequency shielding response section, otherwise, skipping the current frequency gradual change response section, not marking the frequency shielding response section, and continuing to process the next time slice;
After the marking is completed, the time index, center frequency, frequency change speed and amplitude change slope of the frequency mask response section are output and used as disturbance response description data.
In a preferred embodiment, the track reconstruction module is used for extracting frequency direction jump trend of each frequency shielding response section in the disturbance response description data and calculating an incremental change curve between adjacent frequency values;
Judging whether a change section with the frequency increment direction reversing times larger than a preset reversing times threshold value exists in the increment change curve, if the change section meets the condition, marking the change section as a suspected frequency evolution inflection point region, otherwise, marking the frequency shielding response section as a track-free jump characteristic and stopping;
The method comprises the steps of performing forward and backward frequency trend line fitting on a suspected frequency evolution inflection point region to respectively obtain a frequency direction trend line before a shielding section and a frequency direction trend line after the shielding section, extending the frequency direction trend line before the shielding section backwards to a preset appointed fitting time interval according to the termination time of the frequency direction trend line before the shielding section, extending the frequency direction trend line after the shielding section forwards to the preset appointed fitting time interval according to the starting time of the frequency direction trend line after the shielding section, and searching an intersection position point of the lower limit of a frequency difference in an extending overlapping interval of the two frequency direction trend lines to serve as a frequency track connecting point of a frequency shielding response section;
And supplementing the frequency track connection point into a continuous frequency evolution track through interpolation by a fitting function of the frequency track connection point and the frequency direction trend lines at two sides of the frequency shielding response section, and taking the continuous frequency evolution track as a target frequency recovery result.
In a preferred embodiment, the path switching module is configured to perform one-to-one comparison between the target frequency recovery result and the original frequency response sequence output by the microwave broadband instantaneous frequency measurement receiver, and extract a frequency difference sequence between the target frequency recovery result and the original frequency response sequence in the frequency shielding response section;
judging whether the frequency difference value in the continuous time segment in the frequency difference value sequence is larger than a preset tolerance threshold value, if so, replacing the original frequency response sequence with a target frequency recovery result in the time segment to form an updated frequency output sequence;
matching the updated frequency output sequence with the time index of the frequency mask response section to generate a frequency correction output section with a mask compensation mark;
judging whether more than three sections of frequency correction output sections with shielding compensation marks continuously appear in the updated frequency output sequence, if the conditions are met, executing a frequency shielding adaptation switching flow, and switching a frequency measurement path from an original frequency response sequence to a target frequency recovery result;
And marking the frequency measurement path output result after the frequency shielding adaptation switching process as a substitute frequency measurement result in the geomagnetic disturbance environment, and storing the substitute frequency measurement result in the disturbance environment frequency response recording sequence.
In a preferred embodiment, the prediction compensation module is configured to extract all frequency hopping position points from the alternative frequency measurement result, and calculate a frequency hopping error corresponding to each frequency hopping position point to form a frequency hopping error sequence;
judging whether error paragraphs with consistent error directions and time intervals smaller than a preset interval threshold exist in the frequency hopping error sequence, if the error paragraphs meet the conditions, marking the error paragraphs as a frequency disturbance prediction template, otherwise, storing the frequency hopping error sequence as a frequency measurement error record into an error cache;
taking the time interval in the frequency disturbance prediction template as a prediction window period parameter, taking the end time index of the frequency disturbance prediction template as a prediction window starting point, and generating a frequency shielding prediction window;
and the time index covered by the frequency shielding prediction window is used for extracting a corresponding time period in the original frequency response sequence, a predicted frequency track is constructed according to the frequency direction change trend extracted from the frequency disturbance prediction template, and the predicted frequency track is stored in a frequency track cache and marked as an advanced frequency recovery result generated based on disturbance prediction.
In a preferred embodiment, the identification extraction module is defined in the identification extraction moduleFor time slicesWhether marked as a frequency mask response section;
;
Wherein the method comprises the steps ofFor time slicesInner time pointA corresponding frequency response value; For time slicesInner time pointA corresponding amplitude response value; indicating the rate of change of frequency; representing the slope of the amplitude change; For time slicesIs a set of sampling time points; A lower threshold value for the rate of frequency change; an upper threshold value for the rate of change of frequency; a lower threshold value for the slope of the amplitude variation; an upper threshold value which is the slope of the amplitude variation; For time slicesIs a center frequency of (a); Is the upper threshold of the center frequency; Representing time slicesDuration of (2); Is a duration threshold; the logic judgment function is a logic judgment function, wherein the logic judgment function is established as1, otherwise, the logic judgment function is 0; Representing a logical relationship and; Indicating all.
In a preferred embodiment, in the trajectory reconstruction module, a definition is made ofTime for reconstructed frequency evolution traceA value of (a);
;
;
Wherein the method comprises the steps ofThe interpolation function is used for connecting the frequency direction trend line with the frequency track connection point to form a continuous track; Is an interpolation starting point; extending a function of a frequency direction trend line prior to frequency masking the response section; extending a function of a frequency direction trend line after the frequency masking response section; Searching a time index set of interpolation starting points; representing absolute value symbols; representing a time point corresponding to the lower limit of the difference value;
;
Wherein the method comprises the steps ofExtending the function of the trend line in the frequency direction before the frequency mask response section at the interpolation starting pointThe function value of the upper part; Extending the function of the trend line in the frequency direction after the frequency mask response segment at the interpolation starting pointThe function value of the above formulaLinear weighting function representing a continuous multiplication symbol, interpolation sectionThe definition is as follows:
;
Wherein the method comprises the steps ofFor interpolating the duration of the transition interval; the condition range in which the formula is established is expressed.
In a preferred embodiment, the frequency direction trend line extension function preceding the frequency mask response segmentExpressed as:
;
frequency direction trend line extension function after frequency mask response segmentExpressed as:
;
Wherein the method comprises the steps ofTime ofAn original frequency response value thereon; For sliding the width of the time windowRepresenting a continuous multiplication symbol; Second derivative in time of the frequency response; coefficients representing the second derivative of the frequency response in the trend line before the masking segment; Representing a suppression coefficient for the second derivative of the frequency response in the trend line after the masking segment; is an exponential decay factor in the time direction before the masking period; Adding a weight factor to the index in the time direction after the shielding section; an exponential decay function.
In a preferred embodiment, in the path switching module, a path is definedExpressed in timeJudging whether the original result is replaced by the recovery result;
;
;
;
Wherein the method comprises the steps ofTime for the original frequency response sequenceA value of (a); Recovering the result in time for the target frequencyA value of (a); Replacing the threshold value for the frequency difference value; The frequency output value is updated; Is the firstA frequency correction output section with a shading compensation flag; Representing the total number of corrected sections in the current judgment period; Indicating whether to trigger path switching, wherein 1 is switching and 0 is holding; as a logic decision function, the logic decision function is established as 1, otherwise is 0, whereRepresenting a continuous multiplication symbol; Representing absolute value symbols.
In a preferred embodiment, the prediction compensation module is defined inA set of time points in a prediction template;
;
;
Wherein the method comprises the steps ofIs the firstTime index of the jump error; Time for frequency hopping errorThe values above; Representation ofWhen the symbol of (b)The value is +1 whenWhen the value is-1, whenThe value is 0; is the upper threshold of the time interval; Expressed in timeRecovering the result of the predicted frequency; representing a frequency prediction track generation function constructed based on a prediction template and a fitting trend function; Representing a frequency direction change function obtained by historical trend fitting; Is a collective symbol representing all of the conditions satisfiedA set of components; Representing a logical relationship and.
The invention has the technical effects and advantages that:
Aiming at the problems that a weak continuous wave signal is easy to be covered by geomagnetic disturbance background and cannot be demodulated by a traditional frequency measurement structure in a space electromagnetic chromatography task, the invention constructs a low-frequency disturbance response extraction mechanism in the electromagnetic frequency measurement process through a combined threshold recognition mechanism of the frequency change speed and the amplitude change slope, and can judge a shielding section under the condition of not only relying on the center frequency, thereby effectively recovering a blind area signal in a frequency measurement channel;
By analyzing frequency increment inversion behavior in the identified frequency shielding response section, fitting front and back trend lines and connecting point interpolation calculation are executed, a complete frequency evolution track is constructed, a truncated frequency measurement path can be recovered under the nonlinear jump condition, and track integrity and time consistency under continuous frequency measurement are improved;
The triggering conditions of the multi-section shielding compensation marks are designed by adopting a difference comparison and frequency correction output section accumulation judgment strategy between the target frequency recovery result and the original frequency measurement result, so that the dynamic frequency measurement path replacement is realized on the premise of avoiding path oscillation, and the self-adaptive robustness of frequency measurement output in an electromagnetic disturbance environment is effectively enhanced;
The disturbance prediction template and the frequency shielding prediction window are constructed through time distribution and direction trend analysis of the frequency hopping errors, the generation of the predicted frequency track is completed before the frequency measurement processing system enters the shielding state, a predicted compensation path based on a disturbance behavior mode is formed, and the frequency measurement early warning and advanced modeling capacity of the frequency measurement processing system in a periodic disturbance scene is improved.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
Referring to fig. 1 of the specification, a radio frequency signal processing system based on a microwave broadband instantaneous frequency measurement receiver according to an embodiment of the present invention includes an identification extraction module, a track reconstruction module, a path switching module, and a prediction compensation module;
The identification extraction module is used for dividing the original radio frequency data stream into long-time fragments, extracting a frequency response sequence from each time fragment, and marking the time fragments meeting the conditions as frequency shielding response sections according to the threshold judgment results of the frequency change speed and the amplitude change slope;
The track reconstruction module is used for extracting and judging frequency direction jump trend of a frequency shielding response section in disturbance response description data, constructing a frequency track connection point by fitting a frequency direction trend line, complementing the frequency track connection point into a continuous frequency evolution track by interpolation, and forming a target frequency recovery result;
The path switching module is used for comparing the target frequency recovery result with the original frequency response sequence, replacing the original frequency response sequence in a time segment meeting the condition according to the judging result of the frequency difference sequence, judging whether to execute frequency measurement path switching or not through the shielding compensation mark, and generating a replaced frequency measurement result in the geomagnetic disturbance environment;
The prediction compensation module is used for extracting frequency hopping errors in the alternative frequency measurement result, constructing a frequency disturbance prediction template, generating a frequency shielding prediction window, constructing a predicted frequency track according to the frequency direction change trend, and generating an advanced frequency recovery result.
The identification extraction module is used for dividing an original radio frequency data stream acquired by the microwave broadband instantaneous frequency measurement receiver into long-time fragments, and performing discrete extraction on frequency response in each time fragment;
calculating the frequency change speed and the amplitude change slope of the frequency response sequence extracted from each time segment to be used as quantitative expression of frequency behaviors in the time segment;
Judging whether the frequency change speed is in a preset frequency change speed threshold range in at least three continuous time points, and the amplitude change slope is in a preset amplitude change slope threshold range in at least three corresponding continuous time points, if so, marking the time segment as a frequency gradual change response section, otherwise, skipping the current time segment, and continuing to process the next time segment;
judging whether the center frequency of the frequency gradual change response section is smaller than a preset center frequency threshold value, judging whether the duration of the frequency gradual change response section is larger than a preset duration threshold value, if so, marking the frequency gradual change response section as a frequency shielding response section, otherwise, skipping the current frequency gradual change response section, not marking the frequency shielding response section, and continuing to process the next time slice;
After the marking is completed, the time index, center frequency, frequency change speed and amplitude change slope of the frequency mask response section are output and used as disturbance response description data.
The track reconstruction module is used for extracting frequency direction jump trend of each frequency shielding response section in the disturbance response description data and calculating an incremental change curve between adjacent frequency values;
judging whether a change section with the frequency increment direction reversing times larger than a preset reversing times threshold value exists in the increment change curve, if the change section meets the conditions, marking the change section as a suspected frequency evolution inflection point region, otherwise, marking the frequency shielding response section as a track-free jump characteristic, and terminating the subsequent flow;
The method comprises the steps of performing forward and backward frequency trend line fitting on a suspected frequency evolution inflection point region to respectively obtain a frequency direction trend line before a shielding section and a frequency direction trend line after the shielding section, extending the frequency direction trend line before the shielding section backwards to a preset appointed fitting time interval according to the termination time of the frequency direction trend line before the shielding section, extending the frequency direction trend line after the shielding section forwards to the preset appointed fitting time interval according to the starting time of the frequency direction trend line after the shielding section, and searching an intersection position point of the lower limit of a frequency difference in an extending overlapping interval of the two frequency direction trend lines to serve as a frequency track connecting point of a frequency shielding response section;
And supplementing the frequency track connection point into a continuous frequency evolution track through interpolation by a fitting function of the frequency track connection point and the frequency direction trend lines at two sides of the frequency shielding response section, and taking the continuous frequency evolution track as a target frequency recovery result.
The path switching module is used for carrying out one-to-one comparison on the target frequency recovery result and an original frequency response sequence output by the microwave broadband instantaneous frequency measurement receiver, and extracting a frequency difference value sequence of the target frequency recovery result and the original frequency response sequence in the frequency shielding response section;
judging whether the frequency difference value in the continuous time segment in the frequency difference value sequence is larger than a preset tolerance threshold value, if so, replacing the original frequency response sequence with a target frequency recovery result in the time segment to form an updated frequency output sequence;
matching the updated frequency output sequence with the time index of the frequency mask response section to generate a frequency correction output section with a mask compensation mark;
judging whether more than three sections of frequency correction output sections with shielding compensation marks continuously appear in the updated frequency output sequence, if the conditions are met, executing a frequency shielding adaptation switching flow, and switching a frequency measurement path from an original frequency response sequence to a target frequency recovery result;
And marking the frequency measurement path output result after the frequency shielding adaptation switching process as a substitute frequency measurement result in the geomagnetic disturbance environment, and storing the substitute frequency measurement result in the disturbance environment frequency response recording sequence.
The prediction compensation module is used for extracting all frequency hopping position points from the alternative frequency measurement result, calculating the frequency hopping error corresponding to each frequency hopping position point and forming a frequency hopping error sequence;
judging whether error paragraphs with consistent error directions and time intervals smaller than a preset interval threshold exist in the frequency hopping error sequence, if the error paragraphs meet the conditions, marking the error paragraphs as a frequency disturbance prediction template, otherwise, storing the frequency hopping error sequence as a frequency measurement error record into an error cache;
taking the time interval in the frequency disturbance prediction template as a prediction window period parameter, taking the end time index of the frequency disturbance prediction template as a prediction window starting point, and generating a frequency shielding prediction window;
and the time index covered by the frequency shielding prediction window is used for extracting a corresponding time period in the original frequency response sequence, a predicted frequency track is constructed according to the frequency direction change trend extracted from the frequency disturbance prediction template, and the predicted frequency track is stored in a frequency track cache and marked as an advanced frequency recovery result generated based on disturbance prediction.
It should be noted that, in the formula structure related to the scheme, the dimensionless terms can be used as proportional or structural adjusting factors, and only play a role of numerical scaling when being combined with the unit-containing quantity, and a new physical dimension is not introduced, so that the whole expressed unit system is not changed or confused;
secondly, in the formula structure of the scheme, if a plurality of variable items with different physical units are involved, including but not limited to time type, quality type or energy type variables, the joint occurrence of the variable items is a collaborative modeling relation for expressing multiple physical mechanisms, each variable can form a unified structure through function mapping, ratio combination or normalization adjustment, the units are clear, the meaning is clear, and the whole expression accords with a dimension consistency principle and an engineering modeling routine paradigm;
If constants, weights, adjustment factors, threshold parameters, proportion coefficients and the like are designed, the parameters belong to adjustable control parameters oriented to different application environments, the values of the parameters depend on target equipment configuration, data input characteristics and performance optimization targets, and the parameters are converged and set in a reasonable range in a mode of model verification, performance constraint or engineering calibration and the like in an implementation stage;
Definition in an identification extraction moduleFor time slicesWhether marked as frequency mask response segment (yes, 0 no);
;
Wherein the method comprises the steps ofFor time slicesInner time pointA corresponding frequency response value; For time slicesInner time pointA corresponding amplitude response value; Indicating the rate of change of frequency (derivative over time); representing the slope of the amplitude change (derivative over time); For time slicesIs a set of sampling time points; A lower threshold value for the rate of frequency change; an upper threshold value for the rate of change of frequency; a lower threshold value for the slope of the amplitude variation; an upper threshold value of the slope of the amplitude change during the time segmentOn the premise of being identified as a frequency ramp response segment,For time slicesIs a center frequency of (a); Is the upper threshold of the center frequency, and is in the time segmentOn the premise of being identified as a frequency ramp response segment,Representing time slicesDuration of (2); Is a duration threshold; the logic judgment function is a logic judgment function, wherein the logic judgment function is established as1, otherwise, the logic judgment function is 0; representing a logical relationship AND; all are represented, each element in the set satisfying a certain condition for expression.
In the track reconstruction module, definitionTime for reconstructed frequency evolution traceA value of (a);
;
;
Wherein the method comprises the steps ofThe interpolation function is used for connecting the frequency direction trend line with the frequency track connection point to form a continuous track; for the interpolation starting point, the interpolation starting point is the time point corresponding to the minimum difference value of the trend line functions in the two frequency directions in the search interval; extending a function of a frequency direction trend line prior to frequency masking the response section; extending a function of a frequency direction trend line after the frequency masking response section; Searching a time index set of interpolation starting points; representing absolute value symbols; representing a time point corresponding to the lower limit of the difference value;
;
Wherein the method comprises the steps ofExtending the function of the trend line in the frequency direction before the frequency mask response section at the interpolation starting pointThe function value of the upper part; Extending the function of the trend line in the frequency direction after the frequency mask response segment at the interpolation starting pointThe function value of the above formulaLinear weighting function representing a continuous multiplication symbol, interpolation sectionThe definition is as follows:
;
Wherein the method comprises the steps ofFor interpolating the duration of the transition interval; the condition range that the formula holds is expressed for defining that the variable is valid for the formula within the specific interval.
Frequency direction trend line extension function before frequency mask response sectionExpressed as:
;
frequency direction trend line extension function after frequency mask response segmentExpressed as:
;
Wherein the method comprises the steps ofTime ofThe original frequency response value, additionally time in the above formulaThe point in time, representing the current calculated trendRepresenting points in time used to traverse the integration window; For sliding time window width, the sliding time window width is used for constructing trend intervalRepresenting a continuous multiplication symbol; For the second derivative of the frequency response in time, the second derivative of the frequency response in time represents the varying acceleration and is used for judging the smoothness or the sharpness of the trend; The enhancement coefficient of the second derivative of the frequency response in the trend line before the shielding section is represented, the enhancement coefficient of the second derivative of the frequency response in the trend line before the shielding section is used for highlighting the rapid inflection point change in the track before the shielding, in practical application, the value of the enhancement coefficient can be combined with the change steepness degree of the frequency response in a history interval, the enhancement coefficient should be larger when the fluctuation of the response curvature is obvious, and the enhancement coefficient should be moderately reduced when the response is more gentle so as to avoid overfitting; The suppression coefficient of the second derivative of the frequency response in the trend line after the shielding section is represented, the suppression coefficient of the second derivative of the frequency response in the trend line after the shielding section is used for smoothing trend change after the transition section, misleading of local severe disturbance on fitting results is prevented, in practical application, the value is based on fluctuation stability of frequency response data after the shielding section, the suppression capability is properly enhanced when fluctuation is severe, and the limit can be relaxed when the fluctuation rule is clear; For the exponential decay factor in the time direction before the shielding section, the exponential decay factor in the time direction before the shielding section is used for determining the retention degree of the historical frequency response value in trend calculation, the value of the exponential decay factor can be adjusted according to a historical time window covered by trend analysis, if the historical track information is more critical, the decay rate is slowed down, and if only the short-term direction is required to be captured, the decay rate can be increased to increase the responsiveness; The index weighting factors in the time direction behind the shielding section are used for controlling the attention degree of frequency trend modeling to the recent response point, the value of the index weighting factors can be determined according to the predictability of the frequency trend behind the shielding section, the weighting degree is properly increased when the trend is strong in continuity, and the weighting is kept gentle when the trend is uncertain or the oscillation is strong so as to prevent errors; An exponential decay function, wherein the exponential decay function is used for simulating the sensitivity reduction of the distance to the time, and the formula structure in the formula is as follows: is shown in the intervalInternal pair variableFor reflecting trend accumulation.
In the path switching module, definitionExpressed in timeJudging whether the original result is replaced by the recovery result (1 is replaced, and 0 is reserved);
;
;
;
Wherein the method comprises the steps ofTime for the original frequency response sequenceA value of (a); Recovering the result in time for the target frequencyA value of (a); Replacing the threshold value for the frequency difference value; The frequency output value is updated; Is the firstA frequency correction output section with a shading compensation flag; Representing the total number of corrected sections in the current judgment period; Indicating whether to trigger path switching, wherein 1 is switching and 0 is holding; as a logic decision function, the logic decision function is established as 1, otherwise is 0, whereRepresenting a continuous multiplication symbol; Representing absolute value symbols.
Definition in prediction Compensation ModuleA set of time points in a prediction template;
;
;
Wherein the method comprises the steps ofIs the firstTime index of the jump error; Time for frequency hopping errorThe values above; Representation ofWhen the symbol of (b)The value is +1 whenWhen the value is-1, whenThe value is 0; is the upper threshold of the time interval; Expressed in timeRecovering the result of the predicted frequency; representing a frequency prediction track generation function constructed based on a prediction template and a fitting trend function; Representing a frequency direction change function obtained by historical trend fitting; Is a collective symbol representing all of the conditions satisfiedA set of components; Representing a logical relationship AND (AND).
The technical scheme of the invention aims at solving the problem of frequency measurement blind areas caused by frequency shielding phenomenon of weak radio frequency signals due to geomagnetic disturbance in a track observation task, wherein a common frequency measurement model in the prior art adopts a fixed frequency window or linear filter structure, and can not accurately recover signal tracks under strong background interference, and particularly, when nonlinear jump behaviors such as interruption, drift or fall-back occur in a frequency evolution process, the conventional means can not judge whether the frequency continuity is truly interrupted or only shielded by background signals;
The method comprises the steps of firstly identifying an extraction module for bearing the entrance task of a scheme, namely identifying a time segment with frequency shielding characteristics from an original radio frequency data stream acquired by a microwave broadband instantaneous frequency measurement receiver, adopting combined threshold judgment of frequency change speed and amplitude change slope for executing logic, wherein in the stage of frequency shielding, the signal usually presents two characteristics, namely narrowing a frequency fluctuation range, stabilizing amplitude change, keeping continuity of local slope in time dimension even if a weak signal is 'suppressed' to the vicinity of a frequency response base line by background disturbance, and selecting to establish a composite threshold for the speed and direction of a change trend without using a frequency value as a judgment basis in design so as to reduce sensitivity to amplitude and central value deviation;
After the preliminary identification of the shielding response section is completed, the core task of the track reconstruction module is to judge whether the frequency track has the evolution trend of being broken or not, and construct a continuous track at the jump point; in a real scene, the frequency direction change before and after a weak signal is shielded is generally inconsistent, for example, a slowly rising target signal can slide down or stagnate rapidly after being interfered and is easy to be fitted or misjudged after being pressed, so that the model designs a bidirectional fitting structure of forward and backward trend lines, sets a controllable fitting extension time range, searches the minimum frequency difference point in the overlapping area of the trend lines at two sides as a track connecting point, essentially surrounds a shielding section by a known trend, presumes frequency change logic in a frequency area which is not directly observed, and finally reconstructs the shielding section into a continuous track by using a fitting function so as to recover a target frequency path;
The task of the path switching module is not just to output a recovery result, but to judge whether to incorporate the recovery result into the frequency measurement path for replacing the original frequency response sequence; the method comprises the steps of determining a frequency difference value of a frequency correction output section, determining a frequency difference value of a frequency correction output section, and judging whether the frequency difference value exceeds a preset tolerance threshold value or not according to the frequency difference value of the frequency correction output section, wherein the frequency difference value is equal to or less than a preset tolerance threshold value;
The structure is provided for solving the problem that frequency shielding has periodicity or predictability in a track long-term running task, and because a plurality of geomagnetic disturbances have relatively regular behaviors, such as polar disturbance excited by solar wind usually repeatedly occurs at certain track heights, frequency jump error directions and time intervals are extracted from historical substitution frequency measurement results, an error paragraph is constructed, a prediction window can be generated in advance, the prediction window can be used for directly constructing a frequency track for advanced compensation without waiting for explicit identification of a shielding period once the shielding period is covered in an original frequency response sequence, and the structure improves passive compensation into active prediction and is a prospective part in practical application and suitable for the frequency measurement guarantee task in multi-track long-term running.
The foregoing description of the preferred embodiments of the invention is not intended to limit the invention to the precise form disclosed, and any such modifications, equivalents, and alternatives falling within the spirit and principles of the invention are intended to be included within the scope of the invention.