CN108832964A - A kind of FASST signal recognition method and device based on instantaneous frequency - Google Patents
A kind of FASST signal recognition method and device based on instantaneous frequency Download PDFInfo
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- H04B1/69—Spread spectrum techniques
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Abstract
The present invention relates to blipology field, especially a kind of FASST signal recognition method and device based on instantaneous frequency.By the signal data to be processed of acquisition setting length, the matched complex signal of character rate of sample rate Yu FASST signal is converted by pretreatment；The normalization instantaneous frequency of complex signal is calculated using instantaneous correlation method；And according to the spreading code characteristic of FASST signal by all normalization instantaneous frequency sampling points of frequency corresponding to 0 and 1 bit in a spreading code added up to obtain the accumulation of normalization instantaneous frequency and；According to the corresponding normalization instantaneous frequency accumulation of 0 and 1 bit and obtain its zero-mean frequency absolute value of the difference, and judge whether the peak feature of the absolute value meets the first setting peak value condition, if meeting, then it is identified as FASST signal, realize the quick identification to FASST signal, method complexity is low, has good noiseproof feature, solves the problems, such as not accurately identifying FASST signal under the conditions of reception frequency deviation signal.
Description
Technical field
The present invention relates to blipology field, especially a kind of FASST signal recognition method based on instantaneous frequency
And device.
Background technique
The basic task of automatic Modulation type identification is exactly under the given channel conditions, to determine the modulation methods for receiving signal
Formula, and corresponding modulation parameter is provided, foundation is provided for further analysis and processing signal.It is lost in low signal-to-noise ratio and multipath fading
Under the conditions of true, the critical issue that signal identification performance is automatic Modulation type identification how is effectively improved.
For the signal of specific protocol, traditional automatic Modulation type identification can only obtain the modulation system and modulation of signal
Parameter can not determine the protocol type of signal.Simultaneously as not utilizing the prior information of signal, traditional automatic Modulation type
The performance of identification is difficult to improve.For specific protocol signal, verifying identification has better recognition performance.Verifying is identified by
Signal characteristic is extracted to verify a certain signal whether signal to be identified belongs in set, and points out the protocol class of the signal
Type.FASST (Futaba Advanced Spread Spectrum Technology) is the remote control of Japanese double leaf group production
The remote signal of device avoids the signal interference between different remote by the way of spread spectrum plus frequency hopping.The signal is in ISM frequency
Section uses, and signal background is complex, and there are the interference signals of diversified forms, carries out knowledge method for distinguishing using frequency hopping detection and is easy
Be interfered the influence of signal, and recognition effect is bad.The identification of single-hop signal mainly identifies its modulation system, base
It is mainly identified from baseband signal in the recognition methods of likelihood function, needs the centre frequency of known signal, when reception signal
There are when frequency departure, be easy to be influenced to cause signal identification inaccurate by this frequency departure.
Summary of the invention
The object of the present invention is to provide a kind of FASST signal recognition method and device based on instantaneous frequency, to solve
The problem of FASST signal can not being accurately identified under the conditions of reception frequency deviation signal.
In order to realize the quick identification to FASST signal, solve not believing FASST under the conditions of reception frequency deviation signal
The problem of number being accurately identified, the present invention provides a kind of FASST signal recognition method based on instantaneous frequency, including walks as follows
Suddenly：
1) signal data to be processed of acquisition setting length, is converted to sample rate for signal data to be processed by pretreatment
With the matched complex signal of character rate of FASST signal；
2) the normalization instantaneous frequency of complex signal is calculated using instantaneous correlation method；
3) according to the spreading code characteristic of FASST signal, by all of frequency corresponding to 0 and 1 bit in a spreading code
Normalization instantaneous frequency sampling point add up to obtain the accumulation of normalization instantaneous frequency with；
4) according to 0 and 1 bit it is corresponding normalization instantaneous frequency accumulation and obtain its zero-mean or 1 means frequency difference it is exhausted
To value, and judge whether the peak feature of the absolute value meets the first setting peak value condition, if satisfied, being then identified as FASST letter
Number.
Further, in order to promote noise robustness, after obtaining absolute value in step 4), between the grade for also calculating the absolute value
Every sliding accumulation and, and judge this slide at equal intervals accumulate sum peak value whether meet the second setting peak value condition, if satisfied, then
It is identified as FASST signal.
Further, in order to improve the accuracy of signal identification, described first set peak value condition as peak value size between
Between 0.5 overtones band interval and doubled frequency interval, and there are the peak values that spread code length is divided between continuous 16.
Further, in order to improve the accuracy of signal identification, described second set peak value condition as peak value size between
Between M/2 overtones band interval and 2M overtones band interval, and there are the peak value for being divided into spread code length between continuous 16, wherein M is
Accumulate code element number.
Further, in order to carry out further operation to the signal data of acquisition, the pre-treatment step is as follows：
(1) signal data to be processed is transformed to by zero intermediate frequency complex signal by frequency-conversion processing and filtering processing；
(2) sample rate is obtained according to the character rate of FASST signal, signal to be processed is subjected to resampling processing and is converted to
Complex signal.
Further, in order to realize the identification and extraction to complex signal, the instantaneous auto-correlation expression formula of the complex signal is：
R (n, m)=s*(n) s (n+m)=A2exp(j2πfiM), wherein A be signal amplitude, fiFor carrier frequency, m is delay interval, and m
> 0 is extracted by instantaneous correlation method, and calculation formula is as follows：
F in formulasFor the sample frequency of signal, it is as follows that normalization instantaneous frequency is obtained as m=1：
finst(n)=finst(n,1)/fs。
Further, for the identification suitable for FASST signal, according to the spreading code characteristic of FASST signal, FASST letter
Number spreading code be b0=[00011101101], b1=[11100010010], the 1 to 3rd bit, the 7th bit and in spreading code
10 bits correspond to instantaneous frequency f0, the 4 to 6th bit, the 8th bit, the 11st bit correspond to instantaneous frequency f1, to 0,1 ratio in spreading code
Normalization instantaneous frequency corresponding to spy adds up, and the calculation formula for being accumulated sum is as follows：
Wherein, P is over-sampling multiple.
Further, it in order to eliminate influence of the carrier frequency offset to normalization instantaneous frequency accumulation sum, and further mentions
Noise robustness is risen, the zero-mean frequency absolute value of the difference of normalization instantaneous frequency accumulation sum is in step 3)：
Df (n)=| sf0(n)-fmean(n)|
Wherein, fmean(n)=[sf0(n)+sf1(n)]/2。
Further, in order to further enhance noise robustness, every symbol takes the df (n) of 1 sampling point to be accumulated, accumulation
Code element number is M, and the calculation formula that the accumulation sum of sliding at equal intervals of df (n) can be obtained is as follows：
The present invention also provides a kind of FASST signal recognition device based on instantaneous frequency, including memory, processor and
The computer program that can be run in memory and on a processor is stored, the processor is realized following when executing described program
Step：
1) signal data to be processed of acquisition setting length, is converted to sample rate for signal data to be processed by pretreatment
With the matched complex signal of character rate of FASST signal；
2) the normalization instantaneous frequency of complex signal is calculated using instantaneous correlation method；
3) according to the spreading code characteristic of FASST signal, by all of frequency corresponding to 0 and 1 bit in a spreading code
Normalization instantaneous frequency sampling point add up to obtain the accumulation of normalization instantaneous frequency with；
4) according to 0 and 1 bit it is corresponding normalization instantaneous frequency accumulation and obtain its zero-mean or 1 means frequency difference it is exhausted
To value, and judge whether the peak feature of the absolute value meets the first setting peak value condition, if satisfied, being then identified as FASST letter
Number.
Further, after obtaining absolute value in step 4), also calculate the absolute value the accumulation of sliding at equal intervals and, and judge
Whether the peak value for sliding accumulation sum at equal intervals meets the second setting peak value condition, if satisfied, being then identified as FASST signal.
Further, described first to set peak value condition be peak value size between 0.5 overtones band interval and doubled frequency
Between, and there are the peak values that spread code length is divided between continuous 16.
Further, described second to set peak value condition be peak value size between M/2 overtones band interval and 2M overtones band
Between, and there are the peak values that spread code length is divided between continuous 16, and wherein M is accumulation code element number.
Further, the pre-treatment step is as follows：
(1) signal data to be processed is transformed to by zero intermediate frequency complex signal by frequency-conversion processing and filtering processing；
(2) sample rate is obtained according to the character rate of FASST signal, signal to be processed is subjected to resampling processing and is converted to
Complex signal.
Further, in order to realize the identification and extraction to complex signal, the instantaneous auto-correlation expression formula of the complex signal is：
R (n, m)=s*(n) s (n+m)=A2exp(j2πfiM), wherein A be signal amplitude, fiFor carrier frequency, m is delay interval, and m
> 0 is extracted by instantaneous correlation method, and calculation formula is as follows：
F in formulasFor the sample frequency of signal, it is as follows that normalization instantaneous frequency is obtained as m=1：
finst(n)=finst(n, 1)/fs。
Further, the spreading code of FASST signal is b0=[00011101101], b1=[11100010010], spreading code
Interior 1 to 3rd bit, the 7th bit and the 10th bit correspond to instantaneous frequency f0, the 4 to 6th bit, the 8th bit, the 11st bit are corresponding
Instantaneous frequency f1, add up to normalization instantaneous frequency corresponding to 0,1 bit in spreading code, the calculating for being accumulated sum is public
Formula is as follows：
Wherein, P is over-sampling multiple.
Further, the zero-mean frequency absolute value of the difference of normalization instantaneous frequency accumulation sum is in step 3)：
Df (n)=| sf0(n)-fmean(n)|
Wherein, fmean(n)=[sf0(n)+sf1(n)]/2。
Further, in order to further enhance noise robustness, every symbol takes the df (n) of 1 sampling point to be accumulated, accumulation
Code element number is M, and the calculation formula that the accumulation sum of sliding at equal intervals of df (n) can be obtained is as follows：
Detailed description of the invention
Fig. 1 is a kind of flow chart of FASST signal recognition method based on instantaneous frequency；
Fig. 2 is the analog result figure of the normalization instantaneous frequency of FASST signal；
Fig. 3 is the analog result figure of the normalization instantaneous frequency accumulation sum of FASST signal；
Fig. 4 is the analog result of the zero-mean frequency absolute value of the difference of the normalization instantaneous frequency accumulation sum of FASST signal
Figure；
Fig. 5 is the analog result figure of the sliding accumulation sum of the zero-mean difference on the frequency of FASST signal；
Fig. 6 is a kind of flow chart of the improved method of FASST signal identification based on instantaneous frequency.
Specific embodiment
The present invention will be further described in detail with reference to the accompanying drawing.
The present invention provides a kind of FASST signal recognition device based on instantaneous frequency, including memory, processor and deposits
The computer program that can be run in memory and on a processor is stored up, which realizes a kind of based on instantaneous when executing program
The FASST signal recognition method of frequency, as shown in Figure 1, including the following steps：
1, the signal data to be processed for acquiring certain length is converted to sampling after frequency conversion, filtering and resampling processing
Rate and the matched complex signal s (n) of character rate.
It to the signal data of acquisition, needs to make signal zero intermediate frequency complex signal by frequency-conversion processing and filtering processing, allow
There are frequency departures.According to the character rate of target FASST signal, suitable resampling rate is selected, by signal weight to be processed
It is sampled as the complex signal to match with target FASST character rate, so that the integer sampling having the same of each FASST symbol
Point, since FASST signal uses FSK modulation mode, by resampling, so that the over-sampling multiple of each FSK symbol is integer
P。
2, the normalization instantaneous frequency f of complex signal s (n) is calculatedinst(n)。
Complex baseband signal, that is, complex signal s (n) of FASST signal is represented by：
Wherein A is the amplitude of signal,For any first phase, fi is carrier frequency.The instantaneous auto-correlation of the complex signal is represented by：
R (n, m)=s*(n) s (n+m)=A2exp(j2πfim)
Wherein m is delay interval, and m > 0.Therefore, the instantaneous frequency of the complex signal s (n) is mentioned using instantaneous correlation method
It takes, calculation formula is as follows：
Wherein fsFor the sample frequency of signal.Sampling point phase difference obtained instantaneous frequency in front and back is indicated as m=1, to adopting
Normalization instantaneous frequency f is obtained after the normalization of sample rateinst(n)：
finst(n)=finst(n,1)/fs
From figure 2 it can be seen that the frequency interval of normalization instantaneous frequency is 0.125.
3, according to the spreading code characteristic of FASST signal, it is instantaneous to calculate normalization corresponding to 0,1 bit in a spreading code
Frequency accumulation and sf0(n)、sf1(n)。
FASST signal uses Direct Sequence Spread Spectrum (DSSS) technology, spreading code b0=[00011101101], b1=
[11100010010], original information bits every bit expanded after spread spectrum is 11 bit sequences, i.e. original information bits 0 expand
Exhibition is 11 bit b0, original information bits 1 are extended to 11 bit b1.After FSK modulation, the corresponding f of bit 00, the correspondence of bit 1
f1。
According to above-mentioned spreading code, the 1 to 3rd bit, the 7th bit and the 10th bit correspond to instantaneous frequency f in spreading code0, the 4th
Instantaneous frequency f is corresponded to 6 bits, the 8th bit, the 11st bit1.In order to be suitable for FASST signal identification, to 0 in spreading code,
Normalization instantaneous frequency corresponding to 1 bit adds up, and the calculation formula for being accumulated sum is as follows：
Wherein P is over-sampling multiple.
As shown in figure 3, peak value will occur in the initial position of each spreading code after cumulative.
4, the zero-mean frequency absolute value of the difference df (n) of normalization instantaneous frequency accumulation sum is calculated, and judges the absolute value
Peak feature whether meet the first setting peak value condition, if satisfied, being then identified as FASST signal.
Since complex signal s (n) is there may be carrier frequency offset, which is located at f0And f1Centre, therefore,
It can be obtained by averaging, i.e.,
fmean(n)=[sf0(n)+sf1(n)]/2
In order to eliminate influence of the carrier frequency offset to normalization instantaneous frequency accumulation sum, so that the peak value of accumulation sum is more
Obviously, zero-mean frequency absolute value of the difference df (n) is calculated as follows：
Df (n)=| sf0(n)-fmean(n)|
As shown in figure 4, accumulating the simulation of the zero-mean frequency absolute value of the difference of sum for FASST signal normalization instantaneous frequency
Result figure.The 1 i.e. sf of means frequency absolute value of the difference can also be calculated1(n) with the absolute value of the difference of average value, due to effect phase
Together, details are not described herein again.
By above-mentioned steps, the peak feature of df (n) is made decisions by being converted into the identification of FASST signal.df(n)
There is peak value in each code position, theoretical peak size is FSK frequency interval, between two peak values between be divided into spreading code
Length, that is, P × 11.Judgment condition can be set as：With the presence or absence of the peak value for being divided into P × 11 between continuous 16, can then be judged to if it exists
FASST signal, wherein peak value size is between 0.5 overtones band interval and doubled frequency interval.
It further include step to promote noise robustness further on the basis of above-mentioned steps：
5, the accumulation of sliding at equal intervals and the sdf (n) of df (n) are calculated.
Since df (n) peak value occurs in each code position, theoretical peak size is the frequency interval of FSK.In order into
One step promotes noise robustness, does sliding at equal intervals to df (n) and accumulates, i.e., every symbol takes the df (n) of 1 sampling point to be accumulated,
Accumulation code element number is M, and formula is as follows：
The selection of M can be selected according to the case where Signal-to-Noise, and M is bigger, inhibit the ability of noise stronger, accumulation effect
Fruit is better.The result of accumulation as shown in figure 5, from figure 5 it can be seen that the peak value after accumulation is more obvious, and two peak values it
Between between be divided into spread code length.
6, according to the peak feature of sdf (n), suitable threshold value is set and is made decisions, meets judgment condition and then identifies
Otherwise FASST signal is not.
As shown in fig. 6, by above-mentioned steps, by the identification of FASST signal be converted into the peak feature of sdf (n) into
Row judgement.There are peak value, the FSK frequency interval that theoretical peak size is M times, two peak values in each code position in sdf (n)
Between between be divided into spread code length i.e. P × 11.Judgment condition can be set as：With the presence or absence of the peak for being divided into P × 11 between continuous 16
Value, can then be judged to FASST signal, wherein peak value size is between M/2 overtones band interval and 2M overtones band interval if it exists.
Specific embodiment of the present invention is presented above, but the present invention is not limited to described embodiment.
Under the thinking that the present invention provides, to the skill in above-described embodiment by the way of being readily apparent that those skilled in the art
Art means are converted, are replaced, are modified, and play the role of with the present invention in relevant art means it is essentially identical, realize
Goal of the invention it is also essentially identical, the technical solution formed in this way is to be finely adjusted to be formed to above-described embodiment, this technology
Scheme is still fallen in protection scope of the present invention.
Claims (10)
1. a kind of FASST signal recognition method based on instantaneous frequency, which is characterized in that include the following steps：
1) acquisition setting length signal data to be processed, by pretreatment by signal data to be processed be converted to sample rate with
The matched complex signal of the character rate of FASST signal；
2) the normalization instantaneous frequency of complex signal is calculated using instantaneous correlation method；
3) according to the spreading code characteristic of FASST signal, by all normalizings of frequency corresponding to 0 and 1 bit in a spreading code
Change instantaneous frequency sampling point add up to obtain the accumulation of normalization instantaneous frequency with；
4) according to 0 and 1 bit it is corresponding normalization instantaneous frequency accumulation and obtain its zero-mean or 1 means frequency difference it is absolute
Value, and judge whether the peak feature of the absolute value meets the first setting peak value condition, if satisfied, being then identified as FASST signal.
2. the FASST signal recognition method according to claim 1 based on instantaneous frequency, which is characterized in that in step 4)
After obtaining absolute value, also calculate the absolute value sliding at equal intervals accumulation and, and judge this slide at equal intervals accumulate sum peak value
Whether second setting peak value condition is met, if satisfied, being then identified as FASST signal.
3. the FASST signal recognition method according to claim 1 based on instantaneous frequency, which is characterized in that described first
Setting peak value condition is peak value size between 0.5 overtones band interval and doubled frequency interval, and there are continuous 16 intervals
For the peak value of spread code length.
4. the FASST signal recognition method according to claim 2 based on instantaneous frequency, which is characterized in that described second
Setting peak value condition is peak value size between M/2 overtones band interval and 2M overtones band interval, and there are continuous 16 intervals
For the peak value of spread code length, wherein M is accumulation code element number.
5. the FASST signal recognition method according to claim 1,2,3 or 4 based on instantaneous frequency, which is characterized in that institute
It is as follows to state pre-treatment step：
(1) signal data to be processed is transformed to by zero intermediate frequency complex signal by frequency-conversion processing and filtering processing；
(2) sample rate is obtained according to the character rate of FASST signal, signal to be processed is subjected to resampling processing and is converted to letter in reply
Number.
6. a kind of FASST signal recognition device based on instantaneous frequency, including memory, processor and storage are in memory
And the computer program that can be run on a processor, which is characterized in that the processor realizes following step when executing described program
Suddenly：
1) acquisition setting length signal data to be processed, by pretreatment by signal data to be processed be converted to sample rate with
The matched complex signal of the character rate of FASST signal；
2) the normalization instantaneous frequency of complex signal is calculated using instantaneous correlation method；
3) according to the spreading code characteristic of FASST signal, by all normalizings of frequency corresponding to 0 and 1 bit in a spreading code
Change instantaneous frequency sampling point add up to obtain the accumulation of normalization instantaneous frequency with；
4) according to 0 and 1 bit it is corresponding normalization instantaneous frequency accumulation and obtain its zero-mean or 1 means frequency difference it is absolute
Value, and judge whether the peak feature of the absolute value meets the first setting peak value condition, if satisfied, being then identified as FASST signal.
7. the FASST signal recognition device according to claim 6 based on instantaneous frequency, which is characterized in that in step 4)
After obtaining absolute value, also calculate the absolute value sliding at equal intervals accumulation and, and judge this slide at equal intervals accumulate sum peak value
Whether second setting peak value condition is met, if satisfied, being then identified as FASST signal.
8. the FASST signal recognition device according to claim 6 based on instantaneous frequency, which is characterized in that described first
Setting peak value condition is peak value size between 0.5 overtones band interval and doubled frequency interval, and there are continuous 16 intervals
For the peak value of spread code length.
9. the FASST signal recognition device according to claim 7 based on instantaneous frequency, which is characterized in that described second
Setting peak value condition is peak value size between M/2 overtones band interval and 2M overtones band interval, and there are continuous 16 intervals
For the peak value of spread code length, wherein M is accumulation code element number.
10. the FASST signal recognition device according to claim 6,7,8 or 9 based on instantaneous frequency, which is characterized in that
The pre-treatment step is as follows：
(1) signal data to be processed is transformed to by zero intermediate frequency complex signal by frequency-conversion processing and filtering processing；
(2) sample rate is obtained according to the character rate of FASST signal, signal to be processed is subjected to resampling processing and is converted to letter in reply
Number.
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| US20170350985A1 (en) * | 2016-06-06 | 2017-12-07 | Brian G. Agee | Blind despreading of civil GNSS signals for resilient PNT applications |
| CN107490722A (en) * | 2017-08-18 | 2017-12-19 | 南开大学 | A kind of frequency estimating methods of low signal-to-noise ratio real signal |
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| US20160204913A1 (en) * | 2000-06-13 | 2016-07-14 | Comcast Cable Communications, Llc | Transmission of data to multiple nodes |
| US8605830B2 (en) * | 2010-07-30 | 2013-12-10 | National Instruments Corporation | Blind carrier/timing recovery and detection of modulation scheme |
| US20170350985A1 (en) * | 2016-06-06 | 2017-12-07 | Brian G. Agee | Blind despreading of civil GNSS signals for resilient PNT applications |
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