CN114884782B - Decision correction method and device applied to GFSK receiver - Google Patents
Decision correction method and device applied to GFSK receiver Download PDFInfo
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L27/00—Modulated-carrier systems
- H04L27/10—Frequency-modulated carrier systems, i.e. using frequency-shift keying
- H04L27/14—Demodulator circuits; Receiver circuits
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L25/00—Baseband systems
- H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines
- H04L25/03—Shaping networks in transmitter or receiver, e.g. adaptive shaping networks
- H04L25/03006—Arrangements for removing intersymbol interference
- H04L25/03159—Arrangements for removing intersymbol interference operating in the frequency domain
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L27/00—Modulated-carrier systems
- H04L27/10—Frequency-modulated carrier systems, i.e. using frequency-shift keying
- H04L27/14—Demodulator circuits; Receiver circuits
- H04L27/144—Demodulator circuits; Receiver circuits with demodulation using spectral properties of the received signal, e.g. by using frequency selective- or frequency sensitive elements
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L25/00—Baseband systems
- H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines
- H04L25/03—Shaping networks in transmitter or receiver, e.g. adaptive shaping networks
- H04L25/03006—Arrangements for removing intersymbol interference
- H04L2025/0335—Arrangements for removing intersymbol interference characterised by the type of transmission
- H04L2025/03375—Passband transmission
- H04L2025/03394—FSK
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02D—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN INFORMATION AND COMMUNICATION TECHNOLOGIES [ICT], I.E. INFORMATION AND COMMUNICATION TECHNOLOGIES AIMING AT THE REDUCTION OF THEIR OWN ENERGY USE
- Y02D30/00—Reducing energy consumption in communication networks
- Y02D30/70—Reducing energy consumption in communication networks in wireless communication networks
Abstract
The invention discloses a judgment correction method and a judgment correction device applied to a GFSK receiver, wherein when the polarities of a first symbol and a second symbol are the same, the method calculates the gradient between the optimal sampling point of the first symbol and the optimal sampling point of the second symbol, judges whether the first symbol and the second symbol are reverse according to the gradient, if so, the first symbol is corrected to be the reverse value of the second symbol, and if not, the first symbol is not processed; or when the polarities of the first symbol and the second symbol are consistent and the absolute value of the amplitude of the optimal sampling point is smaller than a first threshold value, detecting zero crossing points of two adjacent sampling points in a certain range, and correcting the current symbol of the zero crossing point to be the opposite value of the previous symbol; the zero crossing points refer to the opposite signs of two adjacent sampling points. The technical scheme of the invention improves the decoding accuracy of the decision correction method applied to the GFSK receiver.
Description
Technical Field
The present invention relates to the field of signal decision detection technologies, and in particular, to a decision correction method and apparatus applied to a GFSK receiver.
Background
In the bluetooth technology, a GFSK modulation scheme is adopted. In the GFSK receiver, the calculated frequency word has deviation and even polarity transmission change due to the influence of multiple factors such as inter-code crosstalk, white gaussian noise, frequency offset, time drift and the like; for example, bits of "101" (or "010"), intermediate "0" (or "1"), and "energy" are small and are affected by inter-symbol crosstalk and gaussian white noise of the two-sided symbols, resulting in failure of the symbols of the intermediate bits to "invert" and decoding errors. In order to further improve the robustness of the receiving decision, different detection modes need to be designed to correct the receiving decision result.
In the prior art scheme, CN201811258214 proposes an adaptive equalizer in GFSK receiver; in the patent, a first filter and a second filter are designed to perform forward and reverse filtering to remove intersymbol interference; the first equalization module performs filtering processing on an input signal to obtain a first filtered signal, and works at 4 times of symbol rate; the second equalization module performs filtering processing on the output signal to obtain a second filtered signal, and works at 1 time of symbol rate; an adder for adding the first and second filtered signals to output a summation signal; the judging module is used for judging the summation signals to obtain output signals; the error generation module outputs a first error signal and a second error signal; the first tap coefficient configuration module and the second tap coefficient configuration module are used for generating tap coefficients. In the technology, as two filter structures are designed, 4 times of symbol rate and 1 time of symbol rate operation are needed, and the power consumption is relatively large; meanwhile, the patent does not directly correct the judgment result, and the robustness of the receiving judgment is not directly improved.
Disclosure of Invention
The invention provides a decision correction method and a decision correction device applied to a GFSK receiver, which improve the decoding accuracy of the decision correction method applied to the GFSK receiver.
An embodiment of the present invention provides a decision correction method applied to a GFSK receiver, including the steps of:
when the polarities of the first symbol and the second symbol are the same, calculating the gradient between the optimal sampling point of the first symbol and the optimal sampling point of the second symbol, judging whether the first symbol and the second symbol are opposite according to the gradient, if so, correcting the first symbol to be the opposite value of the second symbol, and if not, not processing;
or when the polarities of the first symbol and the second symbol are consistent and the absolute value of the amplitude of the optimal sampling point is smaller than a first threshold value, detecting zero crossing points of two adjacent sampling points in a certain range, and correcting the current symbol of the zero crossing point to be the opposite value of the previous symbol; the zero crossing points are opposite in sign of two adjacent sampling points;
the first symbol is a current symbol and the second symbol is a symbol preceding the current symbol.
Another embodiment of the present invention provides a decision correction method applied to a GFSK receiver, including the steps of:
when the polarities of the first symbol and the second symbol are consistent, judging whether the absolute value of the amplitude of the optimal sampling point is smaller than a first threshold value or not; the first symbol is a current symbol, and the second symbol is a symbol before the current symbol;
if yes, detecting zero crossing points of two adjacent sampling points in a certain range, and correcting the current symbol of the zero crossing points to be the opposite value of the previous symbol; the zero crossing points are opposite in sign of two adjacent sampling points;
if not, calculating the gradient between the optimal sampling point of the first symbol and the optimal sampling point of the second symbol, judging whether the first symbol and the second symbol are reversed according to the gradient, if so, correcting the first symbol to be the opposite value of the second symbol, and if not, not processing.
Further, a gradient between the optimal sampling point of the first symbol and the optimal sampling point of the second symbol is calculated, and whether the first symbol and the second symbol are inverted or not is judged according to the gradient, if yes, the first symbol is corrected to be an opposite value of the second symbol, specifically:
when a first symbol and a second symbol are judged to be 0, calculating a first gradient between the optimal sampling point of the first symbol and the optimal sampling point of the second symbol, and when the first gradient is larger than a first preset threshold value, correcting the first symbol to be 1;
when the first symbol and the second symbol are both judged to be 1, a second gradient between the optimal sampling point of the first symbol and the optimal sampling point of the second symbol is calculated, and when the second gradient is larger than a second preset threshold value, the first symbol is corrected to be 0.
Further, the detecting zero crossing points of two adjacent sampling points within a certain range specifically includes:
determining a plurality of starting positions and a plurality of ending positions of the certain range according to the first symbol and the second symbol; the certain range is a set of a plurality of combinations of the start position and the end position;
and traversing all adjacent sampling points in the certain range, and detecting zero crossing points of two adjacent sampling points.
Further, the starting position includes a position of an optimal sampling point of a previous symbol, a position of a last sampling point of a previous symbol decoding range, a position of a first sampling point of a current symbol, a position of a first sampling point of the current symbol decoding range, and a position of a last sampling point in a previous symbol period range.
Further, the end position includes a position of the best sampling point of the current symbol, a position of the last sampling point of the current symbol decoding range, and a position of the last sampling point in the current symbol period range.
Another embodiment of the present invention provides a decision detection apparatus applied to a GFSK receiver, including a first detection module or a second detection module;
the first detection module is used for calculating the gradient between the optimal sampling point of the first symbol and the optimal sampling point of the second symbol when the polarities of the first symbol and the second symbol are the same, judging whether the first symbol and the second symbol are reverse according to the gradient, if so, correcting the first symbol to be the reverse value of the second symbol, and if not, not processing; the first symbol is a current symbol, and the second symbol is a symbol before the current symbol;
and the second detection module is used for detecting zero crossing points of two adjacent sampling points in a certain range when the polarities of the first symbol and the second symbol are consistent and the absolute value of the amplitude of the optimal sampling point is lower than a first threshold value, and correcting the current symbol of the zero crossing point to be the opposite value of the previous symbol.
Another embodiment of the present invention provides a decision detection apparatus applied to a GFSK receiver, including a first detection module and a second detection module;
the first detection module is used for detecting zero crossing points of two adjacent sampling points in a certain range when the polarities of the first symbol and the second symbol are consistent and the absolute value of the amplitude of the optimal sampling point is smaller than a first threshold value, and correcting the current symbol of the zero crossing point to be the opposite value of the previous symbol; the first symbol is a current symbol, and the second symbol is a symbol before the current symbol;
and the second detection module is used for calculating the gradient between the optimal sampling point of the first symbol and the optimal sampling point of the second symbol when the polarities of the first symbol and the second symbol are consistent and the absolute value of the amplitude of the optimal sampling point is larger than or equal to a first threshold value, judging whether the first symbol and the second symbol are opposite or not according to the gradient, if so, correcting the first symbol to be the opposite value of the second symbol, and if not, not processing.
The embodiment of the invention has the following beneficial effects:
the invention provides a decision correction method and a device applied to a GFSK receiver. Meanwhile, when the polarities of the first symbol and the second symbol are consistent and the absolute value of the amplitude of the optimal sampling point is smaller than a first threshold value, detecting zero crossing points of two adjacent sampling points in a certain range, correcting the current symbol of the zero crossing points to be the opposite value of the previous symbol, detecting whether the current symbol is correct or not, and correcting the error symbol. Therefore, the invention improves the decoding accuracy of the decision correction method applied to the GFSK receiver.
Drawings
Fig. 1 is a flowchart of a decision correction method applied to a GFSK receiver according to an embodiment of the present invention;
fig. 2 is a schematic flow chart of a decision correction method applied to a GFSK receiver according to an embodiment of the invention;
FIG. 3 is a graph showing the probability density distribution function of homopolar gradient statistics without AWGN;
FIG. 4 is a graph of the heteropolarity gradient statistical probability density distribution function without AWGN;
FIG. 5 is a graph showing the gradient statistical probability density distribution function of heteropolarity adjacent codewords in error decoding;
FIG. 6 is a graph showing the gradient statistical probability density distribution function of homopolar adjacent codewords in error decoding;
fig. 7 is a schematic diagram of demodulation decoding errors of the GFSK receiver;
fig. 8 is a schematic diagram of a relationship among a GFSK receiving symbol period, an optimal sampling point and an access code decoding range of a decision correction method applied to a GFSK receiver according to an embodiment of the invention;
fig. 9 is a schematic view of a zero-crossing detection range of a decision correction method applied to a GFSK receiver according to an embodiment of the invention;
fig. 10 is a schematic structural diagram of a decision detection device applied to a GFSK receiver according to an embodiment of the present invention.
Detailed Description
The following description of the embodiments of the present invention will be made more apparent and fully hereinafter with reference to the accompanying drawings, in which some, but not all embodiments of the invention are shown. 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.
The decision correction method applied to the GFSK receiver provided by the embodiment of the invention comprises the following steps:
as shown in fig. 1, in the decision at the current moment, when the polarities of a first symbol and a second symbol are the same, calculating a gradient between the optimal sampling point of the first symbol and the optimal sampling point of the second symbol, judging whether the first symbol and the second symbol are reverse according to the gradient, if yes, correcting the first symbol to be the reverse value of the second symbol, and if not, not performing processing; the first symbol is a current symbol and the second symbol is a symbol preceding the current symbol. The detection process adopts a gradient detection method (namely a gradient correction method) to detect and correct.
Or in the judgment of the current moment, when the polarities (i.e. demodulation bits) of the first symbol and the second symbol are consistent and the absolute value of the amplitude of the optimal sampling point is smaller than a first threshold value gamma (i.e. a predefined frequency word threshold value), detecting zero crossing points of two adjacent sampling points in a certain range T, and correcting the current symbol of the zero crossing point to be the opposite value of the previous symbol; the zero crossing points refer to the opposite signs of two adjacent sampling points. The detection process adopts a zero-crossing detection method for detection.
When the GFSK receiver receives signals, a symbol polarity judgment method, namely a positive number judgment is generally adopted for judging frequency words as 1; the "negative number" decision is "0". In order to describe the decision word distribution of GFSK receivers, a gradient d (i) =s (i) -S (i-1) is defined; wherein S (i) is a frequency word at the i-th moment; gradient d (i) characterizes the variation of the amplitude difference between adjacent symbols. In the absence of gaussian white noise, the demodulated homopolar symbols have smaller amplitude differences, namely the absolute value of the gradient is smaller, and fig. 3 is a gradient statistical probability density function; in the presence of gaussian white noise, the demodulated heteropolar symbols have a large amplitude difference, i.e. the absolute value of the gradient is large, as shown in fig. 4. In the presence of AWGN (white gaussian noise), the probability density function of the gradient statistics changes. When decoding errors, adjacent codewords that are of opposite polarity are translated into "homopolar" codewords due to the smaller gradient, as shown in fig. 5. On the other hand, when decoding errors, the adjacent code words with the same polarity are translated into the code words with different polarities due to the gradient, as shown in fig. 6.
As one embodiment, a gradient between the optimal sampling point of the first symbol and the optimal sampling point of the second symbol is calculated, and whether the first symbol and the second symbol are inverted is determined according to the gradient, if yes, the first symbol is corrected to be an opposite value of the second symbol, specifically:
when both the first symbol and the second symbol are judged to be 0, a first gradient d (i) between the optimal sampling point S (i) of the first symbol and the optimal sampling point S (i-1) of the second symbol is calculated, and when the first gradient d (i) is larger than a first preset threshold alpha, the first symbol is corrected to be 1. The first gradient may be an amplitude difference between a maximum value of a sampling point in a sampling period of the first symbol and a minimum value of a sampling point in a sampling period of the second symbol. By this process, omission of 0 to 1 variation can be achieved.
When both the first symbol and the second symbol are judged to be 1, a second gradient d (i) between the optimal sampling point S (i) of the first symbol and the optimal sampling point S (i-1) of the second symbol is calculated, and when the second gradient d (i) is larger than a second preset threshold value beta, the first symbol is corrected to be 0. By this process, omission of 1 to 0 variation can be achieved. The second gradient may be an amplitude difference between a minimum value of the sampling points in the sampling period of the first symbol and a maximum value of the sampling points in the sampling period of the second symbol. The gradient in the embodiment of the invention refers to the difference between the amplitudes of the optimal sampling points corresponding to the previous symbol and the current symbol in the sampling period.
The embodiment of the invention mainly aims at detecting the gradient when homopolar demodulation is judged, and realizing the secondary correction of the judgment result. In this way, for a 010/101 type symbol, the middle symbol may have a polarity consistent with the symbols of the preceding and following symbols, however, a change in gradient, due to the presence of inter-symbol cross talk and gaussian white noise. In this case, the symbol can be corrected by the present invention.
When the GFSK receiver is affected by multiple factors such as inter-code crosstalk, gaussian white noise, frequency offset, time drift, etc., in the case of an optimal sampling point, the symbol energy of the present decision may not be the optimal value, so that the symbol polarity error at the optimal sampling point is caused, as shown in fig. 7. The embodiment of the invention captures the polarity change caused by the energy peak by adopting a zero-crossing detection method.
At GFSK reception, the optimal sampling point is typically determined by the access code. When determining the optimal sampling point, there are often multiple sampling points that meet the decoding requirement, and the range of the multiple sampling points can be used as one of the parameters of the zero-crossing detection, namely, the range of sampling points that can be decoded by the access code. As shown in fig. 8, the relationship between the GFSK reception symbol period, the optimal sampling point, and the access code decoding range can be known.
As one embodiment, the detecting zero crossing points of two adjacent sampling points within a certain range specifically includes:
determining a plurality of starting positions and a plurality of ending positions of the certain range according to the first symbol and the second symbol; as shown in fig. 9, the certain range is a set of a plurality of combinations (t 1, t2, t3, t 4) of the start position and the end position;
and traversing all adjacent sampling points in the certain range, and detecting zero crossing points of two adjacent sampling points. If the sign of adjacent 2 samples is "opposite", then a "zero crossing" can be considered to exist; otherwise there is no "zero crossing".
As one embodiment, the starting position includes a position of the best sampling point of the previous symbol, a position of the last sampling point of the previous symbol decoding range (i.e., the access code decodable sample range), a position of the first sampling point of the current symbol decoding range (i.e., the access code decodable sample range), and a position of the last sampling point within the previous symbol period range.
As one of the embodiments, the end position includes the position of the best sample point of the current symbol, the position of the last sample point of the current symbol decoding range (i.e., the access code decodable sample point range), and the position of the last sample point within the current symbol period range.
GFSK receivers may be affected by multiple factors such as inter-symbol interference, white gaussian noise, frequency offset, time drift, etc., which may lead to decoding errors. The invention adopts two schemes: zero crossing detection and gradient detection, and correcting the judgment result of the receiver to capture weak signal with changed symbol so as to correct the judgment result. This approach is most effective for correcting the result when the middle bit is opposite in polarity to the two bits next to it. For example, when a "101" codeword is transmitted, the symbols of the three best sampling points may be "positive", "positive"; however, zero crossing points exist between the middle symbol and the first symbol in the sample point range, so that the judgment result can be corrected through zero crossing detection; if no zero crossing point exists, but the gradient meets the descending trend, the judgment result can be corrected by a gradient detection method. The embodiment of the invention can enhance the robustness of the receiver decision demodulation, improve the decoding performance and accuracy and improve the sensitivity of the receiver.
As shown in fig. 2, another embodiment of the present invention provides a decision correction method applied to a GFSK receiver, including the following steps:
in GFSK receivers, zero crossing detection parameters are defined: threshold gamma, detection range start position a, end position b; defining gradient detection parameters: a first preset threshold α (i.e., a first gradient threshold), a second preset threshold β (i.e., a second gradient threshold);
when the polarities of the first symbol and the second symbol are consistent, judging whether the absolute value of the amplitude of the optimal sampling point is smaller than a first threshold value or not; the first symbol is a current symbol, and the second symbol is a symbol before the current symbol;
if yes, detecting zero crossing points of two adjacent sampling points in a certain range, and correcting the current symbol of the zero crossing points to be the opposite value of the previous symbol; the zero crossing points are opposite in sign of two adjacent sampling points;
if not, calculating the gradient between the optimal sampling point of the first symbol and the optimal sampling point of the second symbol, judging whether the first symbol and the second symbol are reversed according to the gradient, if so, correcting the first symbol to be the opposite value of the second symbol, and if not, not processing.
As one embodiment, a gradient between the optimal sampling point of the first symbol and the optimal sampling point of the second symbol is calculated, and whether the first symbol and the second symbol are inverted or not is judged according to the gradient, if yes, the first symbol is corrected to be an opposite value of the second symbol, specifically:
when both the first symbol and the second symbol are judged to be 0, a first gradient d (i) between the optimal sampling point S (i) of the first symbol and the optimal sampling point S (i-1) of the second symbol is calculated, and when the first gradient d (i) is larger than a first preset threshold alpha, the first symbol is corrected to be 1. The first gradient may be an amplitude difference between a maximum value of a sampling point in a sampling period of the first symbol and a minimum value of a sampling point in a sampling period of the second symbol. By this process, omission of 0 to 1 variation can be achieved.
When both the first symbol and the second symbol are judged to be 1, a second gradient d (i) between the optimal sampling point S (i) of the first symbol and the optimal sampling point S (i-1) of the second symbol is calculated, and when the second gradient d (i) is larger than a second preset threshold value beta, the first symbol is corrected to be 0. The second gradient may be an amplitude difference between a minimum value of the sampling points in the sampling period of the first symbol and a maximum value of the sampling points in the sampling period of the second symbol. By this process, omission of 1 to 0 variation can be achieved.
As one embodiment, the detecting zero crossing points of two adjacent sampling points within a certain range specifically includes:
determining a plurality of starting positions and a plurality of ending positions of the certain range according to the first symbol and the second symbol; as shown in fig. 9, the certain range is a set of a plurality of combinations (t 1, t2, t3, t 4) of the start position and the end position;
and traversing all adjacent sampling points in the certain range, and detecting zero crossing points of two adjacent sampling points. If the sign of adjacent 2 samples is "opposite", then a "zero crossing" can be considered to exist; otherwise there is no "zero crossing".
As one embodiment, the starting position includes a position of the best sampling point of the previous symbol, a position of the last sampling point of the previous symbol decoding range (i.e., the access code decodable sample range), a position of the first sampling point of the current symbol decoding range (i.e., the access code decodable sample range), and a position of the last sampling point within the previous symbol period range.
As one of the embodiments, the end position includes the position of the best sample point of the current symbol, the position of the last sample point of the current symbol decoding range (i.e., the access code decodable sample point range), and the position of the last sample point within the current symbol period range.
As shown in fig. 10, another embodiment of the present invention provides a decision detection apparatus applied to a GFSK receiver, including a first detection module and a second detection module;
the first detection module is used for detecting zero crossing points of two adjacent sampling points in a certain range when the polarities of the first symbol and the second symbol are consistent and the absolute value of the amplitude of the optimal sampling point is smaller than a first threshold value, and correcting the current symbol of the zero crossing point to be the opposite value of the previous symbol; the first symbol is a current symbol, and the second symbol is a symbol before the current symbol;
and the second detection module is used for calculating the gradient between the optimal sampling point of the first symbol and the optimal sampling point of the second symbol when the polarities of the first symbol and the second symbol are consistent and the absolute value of the amplitude of the optimal sampling point is larger than or equal to a first threshold value, judging whether the first symbol and the second symbol are opposite or not according to the gradient, if so, correcting the first symbol to be the opposite value of the second symbol, and if not, not processing.
For convenience and brevity of description, the decision detection device applied to the GFSK receiver in this embodiment of the present apparatus includes all the implementation manners in the above decision correction method embodiment applied to the GFSK receiver, which are not described herein again.
It should be noted that the above-described apparatus embodiments are merely illustrative, and the units described as separate units may or may not be physically separate, and units shown as units may or may not be physical units, may be located in one place, or may be distributed over a plurality of network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of this embodiment. In addition, in the drawings of the embodiment of the device provided by the invention, the connection relation between the modules represents that the modules have communication connection, and can be specifically implemented as one or more communication buses or signal lines. Those of ordinary skill in the art will understand and implement the present invention without undue burden.
While the foregoing is directed to the preferred embodiments of the present invention, it will be appreciated by those skilled in the art that changes and modifications may be made without departing from the principles of the invention, such changes and modifications are also intended to be within the scope of the invention.
Those skilled in the art will appreciate that implementing all or part of the above-described embodiments may be accomplished by way of computer programs, which may be stored on a computer readable storage medium, which when executed may comprise the steps of the above-described embodiments. The storage medium may be a magnetic disk, an optical disk, a Read-Only Memory (ROM), a random access Memory (Random Access Memory, RAM), or the like.
Claims (6)
1. A decision correction method for GFSK receiver, comprising the steps of:
when the polarities of the first symbol and the second symbol are the same, calculating the gradient between the optimal sampling point of the first symbol and the optimal sampling point of the second symbol, judging whether the first symbol and the second symbol are opposite according to the gradient, if so, correcting the first symbol to be the opposite value of the second symbol, and if not, not processing;
or when the polarities of the first symbol and the second symbol are consistent and the absolute value of the amplitude of the optimal sampling point is smaller than a first threshold value, detecting zero crossing points of two adjacent sampling points in a certain range, and correcting the current symbol of the zero crossing point to be the opposite value of the previous symbol; the zero crossing points are opposite in sign of two adjacent sampling points;
the first symbol is a current symbol, and the second symbol is a symbol before the current symbol;
wherein the plurality of starting positions and the plurality of ending positions of the certain range are determined according to the first symbol and the second symbol; the certain range is a set of a plurality of combinations of the start position and the end position;
the initial position comprises the position of the optimal sampling point of the previous symbol, the position of the last sampling point of the previous symbol decoding range, the position of the first sampling point of the current symbol decoding range and the position of the last sampling point in the previous symbol period range;
the end position includes a position of the best sample point of the current symbol, a position of the last sample point of the current symbol decoding range, and a position of the last sample point within the current symbol period range.
2. A decision correction method for GFSK receiver, comprising the steps of:
when the polarities of the first symbol and the second symbol are consistent, judging whether the absolute value of the amplitude of the optimal sampling point is smaller than a first threshold value or not; the first symbol is a current symbol, and the second symbol is a symbol before the current symbol;
if yes, detecting zero crossing points of two adjacent sampling points in a certain range, and correcting the current symbol of the zero crossing points to be the opposite value of the previous symbol; the zero crossing points are opposite in sign of two adjacent sampling points;
if not, calculating the gradient between the optimal sampling point of the first symbol and the optimal sampling point of the second symbol, judging whether the first symbol and the second symbol are reverse according to the gradient, if so, correcting the first symbol to be the reverse value of the second symbol, and if not, not processing;
wherein the plurality of starting positions and the plurality of ending positions of the certain range are determined according to the first symbol and the second symbol; the certain range is a set of a plurality of combinations of the start position and the end position;
the initial position comprises the position of the optimal sampling point of the previous symbol, the position of the last sampling point of the previous symbol decoding range, the position of the first sampling point of the current symbol decoding range and the position of the last sampling point in the previous symbol period range;
the end position includes a position of the best sample point of the current symbol, a position of the last sample point of the current symbol decoding range, and a position of the last sample point within the current symbol period range.
3. The method for decision correction applied to GFSK receiver according to claim 1 or 2, characterized by calculating a gradient between the optimal sampling point of the first symbol and the optimal sampling point of the second symbol and determining whether the first symbol and the second symbol are inverted according to the gradient, if so, correcting the first symbol to be the opposite value of the second symbol, specifically:
when a first symbol and a second symbol are judged to be 0, calculating a first gradient between the optimal sampling point of the first symbol and the optimal sampling point of the second symbol, and when the first gradient is larger than a first preset threshold value, correcting the first symbol to be 1;
when the first symbol and the second symbol are both judged to be 1, a second gradient between the optimal sampling point of the first symbol and the optimal sampling point of the second symbol is calculated, and when the second gradient is larger than a second preset threshold value, the first symbol is corrected to be 0.
4. The decision-modifying method for GFSK receiver of claim 3, wherein detecting zero crossing points of two adjacent sampling points within a certain range comprises:
and traversing all adjacent sampling points in the certain range, and detecting zero crossing points of two adjacent sampling points.
5. A decision detection device applied to a GFSK receiver, comprising a first detection module or a second detection module;
the first detection module is used for calculating the gradient between the optimal sampling point of the first symbol and the optimal sampling point of the second symbol when the polarities of the first symbol and the second symbol are the same, judging whether the first symbol and the second symbol are reverse according to the gradient, if so, correcting the first symbol to be the reverse value of the second symbol, and if not, not processing; the first symbol is a current symbol, and the second symbol is a symbol before the current symbol;
the second detection module is used for detecting zero crossing points of two adjacent sampling points in a certain range when the polarities of the first symbol and the second symbol are consistent and the absolute value of the amplitude of the optimal sampling point is lower than a first threshold value, and correcting the current symbol of the zero crossing point to be the opposite value of the previous symbol;
wherein the plurality of starting positions and the plurality of ending positions of the certain range are determined according to the first symbol and the second symbol; the certain range is a set of a plurality of combinations of the start position and the end position;
the initial position comprises the position of the optimal sampling point of the previous symbol, the position of the last sampling point of the previous symbol decoding range, the position of the first sampling point of the current symbol decoding range and the position of the last sampling point in the previous symbol period range;
the end position includes a position of the best sample point of the current symbol, a position of the last sample point of the current symbol decoding range, and a position of the last sample point within the current symbol period range.
6. A decision detection device applied to a GFSK receiver, comprising a first detection module and a second detection module;
the first detection module is used for detecting zero crossing points of two adjacent sampling points in a certain range when the polarities of the first symbol and the second symbol are consistent and the absolute value of the amplitude of the optimal sampling point is smaller than a first threshold value, and correcting the current symbol of the zero crossing point to be the opposite value of the previous symbol; the first symbol is a current symbol, and the second symbol is a symbol before the current symbol;
wherein the plurality of starting positions and the plurality of ending positions of the certain range are determined according to the first symbol and the second symbol; the certain range is a set of a plurality of combinations of the start position and the end position;
the initial position comprises the position of the optimal sampling point of the previous symbol, the position of the last sampling point of the previous symbol decoding range, the position of the first sampling point of the current symbol decoding range and the position of the last sampling point in the previous symbol period range;
the end position comprises the position of the optimal sampling point of the current symbol, the position of the last sampling point of the decoding range of the current symbol and the position of the last sampling point in the range of the current symbol period;
and the second detection module is used for calculating the gradient between the optimal sampling point of the first symbol and the optimal sampling point of the second symbol when the polarities of the first symbol and the second symbol are consistent and the absolute value of the amplitude of the optimal sampling point is larger than or equal to a first threshold value, judging whether the first symbol and the second symbol are opposite or not according to the gradient, if so, correcting the first symbol to be the opposite value of the second symbol, and if not, not processing.
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