CN107404450A - The method and device of demodulated signal - Google Patents
The method and device of demodulated signal Download PDFInfo
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- CN107404450A CN107404450A CN201710652247.5A CN201710652247A CN107404450A CN 107404450 A CN107404450 A CN 107404450A CN 201710652247 A CN201710652247 A CN 201710652247A CN 107404450 A CN107404450 A CN 107404450A
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Abstract
The application is related to wireless communication technology field, more particularly to how to demodulate FSK and/or GFSK signals.The application provides the method and device of demodulated signal.In the embodiment of the present application, offset estimation is carried out in frequency domain, and frequency deviation compensation is (namely realizing that frequency deviation compensates in frequency domain) that the signal after being converted to DSTFT compensates.Frequency deviation compensation is carried out in time domain relative to based on the non-coherent demodulation of time domain, has more antijamming capability in the frequency deviation compensation that frequency domain is carried out.Because the embodiment of the present application is without going out the carrier wave with signal sending end with frequency with phase in local recovery, therefore the application demodulation method is simple, also not high to hardware requirement.
Description
Technical field
The application is related to wireless communication technology field, more particularly to the method and device of demodulated signal.
Background technology
FSK (Frequency-shift keying, frequency shift keying), GFSK (Gauss frequency Shift
Keying, GFSK Gaussian Frequency Shift Keying) it is modulation system common in digital communication.Due to it, demodulation delay is short, is easily achieved, and has
There is stronger anti-interference and fading capability, thus be widely applied in middle low-speed data communication field.
In recent years, as low speed low-power consumption Wide Area Network is in water power metering, smart home, municipal administration, intelligent irrigation etc.
The extensive use of each side, FSK/GFSK modulation obtain extensive concern.
Traditional FSK/GFSK demodulation method mainly has the non-coherent demodulation method of coherent demodulation and time domain, wherein：
Coherent demodulation method is optimal demodulation scheme of the FSK/GFSK signals under Gaussian white noise channel, is had best
Demodulate effect.But coherent demodulation method needs to go out the carrier wave with signal sending end with frequency with phase in local recovery, thus it is relevant
The complex designing of demodulation method, the requirement to hardware are high.
The non-coherent demodulation method of time domain mainly has frequency-discrimination method, cross zero detecting method, orthogonal from time expander method etc..The non-phase of time domain
Dry demodulation implementation is typically simpler than coherent demodulation, low to hardware requirement.But the non-coherent demodulation of time domain is in low signal-to-noise ratio
(SNR) performance is poorer than coherent demodulation method effect under the conditions of, so the anti-interference of time domain non-coherent demodulation method is poor.
In summary, the existing demodulation method for FSK and/or GFSK signals, otherwise it is high to hardware requirement, otherwise it is anti-
Interference is poor.It is so, it is necessary to a kind of lower than the reduction hardware requirement of coherent demodulation while can resist than the non-coherent demodulation of time domain
The good signal demodulating method of interference.
The content of the invention
The embodiment of the present application provides the method and device of demodulated signal, or to solve present in prior art to hard
Part requires high, or the problem of anti-interference difference etc..
In a first aspect, the embodiment of the present application provides a kind of method of demodulated signal, applied to FSK, and/or, GFSK is described
Method includes：
During real-time reception signal, down coversion is carried out successively to the signal received in real time, modulus samples and low
Zero intermediate frequency data signal is obtained after pass filter processing；
To the zero intermediate frequency data signal carry out DSTFT (Discrete Short Time Fourier Transfor, from
Dissipate Short Time Fourier Transform), the data signal after being converted；
The data signal after the conversion of a Baud Length is often obtained, calculates the energy of the data signal of the Baud Length,
Energy as a symbol；
If the energy of the symbol of continuous specified quantity exceedes energy threshold, since the specified symbol more than energy threshold
The symbol of specified number is determined, specifies the symbol of number to carry out offset estimation according to this in frequency domain, and be followed by offset estimation
Data signal after the DSTFT conversion of the signal received carries out frequency deviation compensation；
Signal after compensating frequency deviation carries out symbol synchronization, and determines the start bit of symbol received after symbol synchronization
Put；
Since original position, frequency is being specified according to signal of the symbol after DSTFT conversion to each code element
Spectral peak distribution at point, and the corresponding relation of the distribution of default spectral peak and demodulation result, determine the demodulation result of the symbol.
Further, methods described also includes：
The energy threshold is determined according to following methods：
It is determined that in the current update cycle energy of symbol minimum value；
According to following energy threshold more new formula, energy threshold is updated；
Thadj(i+1)=λ (Thadj(i)+Emin(i)*C)
Wherein, Thadj(i+1) energy threshold after renewal is represented；Thadj(i) energy threshold before renewal is represented；Emin(i)
Represent the minimum value of the energy of symbol in the current update cycle；λ is less than 1, is preset ratio coefficient；C is default renewal coefficient.
Further, if the signal received is the useful signal that signal sending end is sent, before the signal received
Leading code includes the first sub- lead code for symbol synchronization；Wherein, the described first sub- lead code is by full 0 symbol and all-ones member
It is alternately arranged composition；
Signal after the compensation to frequency deviation carries out symbol synchronization, specifically includes：
After frequency deviation compensation, determine to proceed by the preliminary original position of symbol synchronization from the described first sub- lead code；And
Using the symbol where the preliminary original position as current sync symbol, and using the preliminary original position as deserving preamble
The original position of member；
To deserve the original positions of preamble symbols forward, each mobile current sync step-length backward, after obtaining moving step length
Two code elements；
DSTFT conversion is carried out respectively to the two code elements after moving step length；
Compare energy size of the two code elements after current sync symbol and its moving step length at corresponding frequency；Wherein,
The corresponding frequency of current sync symbol refers to for representing frequency of the symbol for full 0 symbol or all-ones member；
In two code elements after current sync symbol and its moving step length, the original position of the maximum symbol of energy is selected
Start position as next symbol；
Judge whether current symbol synchronization number reaches specified synchronization times；
If so, then terminate symbol synchronization；
If it is not, then update current sync step-length according to exponential decrease rule；And using next symbol as current sync code
Returned after member perform will deserve the original positions of preamble symbols forward, each mobile current sync step-length backward, obtain moving step
The step of two code elements after length.
Further, the second sub- lead code for offset estimation is also included in the lead code, in the lead code
First sub- lead code is located at after the second sub- lead code；The second sub- lead code is full 0 symbol or all-ones member；
In frequency domain according to specifying the symbol of number to carry out offset estimation, specifically include：
Specifying the symbol of number to carry out FFT this, (Fast Fourier Transformation, fast Fourier become
Change)；
In the frequency spectrum of FFT result, frequency corresponding to spectrum peak position is detected；
Frequency and respective standard frequency, determine frequency deviation result according to corresponding to spectrum peak position；Wherein, if the second son is leading
Code is full 0 symbol, then respective standard frequency is the frequency used for representing full 0 symbol；If the second sub- lead code is all-ones
Member, then respective standard frequency is the frequency used for representing all-ones member.
Further, before the signal after compensating frequency deviation carries out symbol synchronization, methods described also includes：
The first default number of symbols being more than according to first energy in the element position of energy threshold, the second sub- lead code
And first the second default number of symbols in sub- lead code, determine the second sub- lead code for symbol synchronization.
Further, in the two code elements after current sync symbol and its moving step length, the maximum symbol of energy is selected
Start position of the original position as next symbol after, methods described also includes：
The start position of the maximum symbol of the energy is recorded relative to the skew of preliminary original position；
The original position of symbol received after symbol synchronization is determined, is specifically included：
The multiple skews obtained in element synchronization are counted, select the most skew of occurrence number as final
Skew；
According to final skew, the original position of symbol received after symbol synchronization is determined.
Further, initial synchronisation step-length is the half of a Baud Length；
It is described to update current sync step-length according to exponential decrease rule, specifically include：
Current sync step-length is updated according to below equation；
λn+1=max (λn/ 2,1)
Wherein, λn+1Represent the current sync step-length after renewal；λnRepresent the current sync step-length before renewal；Represent.
Further, methods described also includes：
The symbol of the specified number for offset estimation is determined according to following methods：
According to the resolution ratio of offset estimation, the specified number is determined, the resolution ratio of wherein offset estimation is higher, the finger
It is more to determine number.
Second aspect, the embodiment of the present application also provides a kind of device of demodulated signal, described applied to FSK and/or GFSK
Device includes：
Pretreatment module, for during real-time reception signal, carrying out lower change successively to the signal received in real time
Frequently, zero intermediate frequency data signal is obtained after modulus sampling and low-pass filtering treatment；
DSTFT conversion modules, for carrying out DSTFT conversion, the numeral after being converted to the zero intermediate frequency data signal
Signal；
Energy computation module, the data signal after conversion for often obtaining a Baud Length, calculates the Baud Length
Data signal energy, the energy as a symbol；
Frequency offset compensation block, if the energy for the symbol of continuous specified quantity exceedes energy threshold, from more than energy
The specified symbol of threshold value starts to determine the symbol for specifying number, specifies the symbol of number to carry out frequency deviation according to this in frequency domain and estimates
Meter, and the data signal after the DSTFT conversion of the signal to being received after offset estimation carries out frequency deviation compensation；
Symbol synchronization module, symbol synchronization is carried out for the signal after compensating frequency deviation, and received after determining symbol synchronization
The original position of the symbol arrived；
Demodulation module 706, for since original position, being converted to each code element according to the symbol by the DSTFT
Signal afterwards is specifying the distribution of the spectral peak at frequency, and the corresponding relation of the distribution of default spectral peak and demodulation result, it is determined that should
The demodulation result of symbol.
Further, described device also includes：
Adaptive energy threshold determination module, for determining the energy threshold according to following methods：
It is determined that in the current update cycle energy of symbol minimum value；
According to following energy threshold more new formula, energy threshold is updated；
Thadj(i+1)=λ (Thadj(i)+Emin(i)*C)
Wherein, Thadj(i+1) energy threshold after renewal is represented；Thadj(i) energy threshold before renewal is represented；Emin(i)
Represent the minimum value of the energy of symbol in the current update cycle；λ is less than 1, is preset ratio coefficient；C is default renewal coefficient.
Further, if the signal received is the useful signal that signal sending end is sent, before the signal received
Leading code includes the first sub- lead code for symbol synchronization；Wherein, the described first sub- lead code is by full 0 symbol and all-ones member
It is alternately arranged composition；
The symbol synchronization module, is specifically included：
Initial synchronization unit, after compensating for frequency deviation, determine to proceed by symbol synchronization from the described first sub- lead code
Preliminary original position；And using the symbol where the preliminary original position as current sync symbol, and by the preliminary start bit
Put as the original position for deserving preamble symbols；
Mobile unit, for will deserve the original positions of preamble symbols forward, each mobile current sync step-length backward, obtain
Two code elements after to moving step length；
DSTFT converter units, for carrying out DSTFT conversion respectively to the two code elements after moving step length；
Comparing unit, for comparing the energy of current sync symbol and the two code elements after its moving step length at corresponding frequency
Measure size；Wherein, the corresponding frequency of current sync symbol refers to for representing frequency of the symbol for full 0 symbol or all-ones member；
Selecting unit, in the two code elements after current sync symbol and its moving step length, selecting energy maximum
Start position of the original position of symbol as next symbol；
Whether judging unit, the symbol synchronization number for judging current reach specified synchronization times；
Processing unit, if for reaching specified synchronization times, terminate symbol synchronization；If not up to specifying synchronization times,
Then current sync step-length is updated according to exponential decrease rule；And performed next symbol as return after current sync symbol
To deserve the original positions of preamble symbols forward, each mobile current sync step-length backward, obtain two codes after moving step length
The step of member.
Further, the second sub- lead code for offset estimation is also included in the lead code, in the lead code
First sub- lead code is located at after the second sub- lead code；The second sub- lead code is full 0 symbol or all-ones member；
Frequency offset compensation block, specifically include：
FFT unit, for specifying the symbol of number to carry out FFT to this；
Detection unit, in the frequency spectrum of FFT result, detecting frequency corresponding to spectrum peak position；
Frequency deviation result determining unit, for the frequency according to corresponding to spectrum peak position and respective standard frequency, determines frequency deviation
As a result；Wherein, if the second sub- lead code is full 0 symbol, respective standard frequency is the frequency used for representing full 0 symbol；
If the second sub- lead code is all-ones member, respective standard frequency is the frequency used for representing all-ones member.
Further, described device also includes：
Sub- lead code identification module, for symbol synchronization module to frequency deviation compensate after signal carry out symbol synchronization it
Before, according to first energy be more than the first default number of symbols in the element position of energy threshold, the second sub- lead code and
The second default number of symbols in first sub- lead code, determines the second sub- lead code for symbol synchronization.
Further, described device also includes：
Logging modle is offset, in two code elements of the selecting unit after current sync symbol and its moving step length,
After selecting start position of the original position of the maximum symbol of energy as next symbol, the maximum symbol of the energy is recorded
Start position relative to preliminary original position skew；
Symbol synchronization module, is specifically included：
Selecting unit is offset, for being counted to the multiple skews obtained in element synchronization, selects occurrence number
Most skews are as final skew；
Symbol original position determining unit, for the symbol that according to final skew, determines to receive after symbol synchronization
Original position.
Further, initial synchronisation step-length is the half of a Baud Length；
The processing unit, specifically for updating current sync step-length according to below equation；
λn+1=max (λn/ 2,1)
Wherein, λn+1Represent the current sync step-length after renewal；λnRepresent the current sync step-length before renewal；Represent.
Further, described device also includes：
The symbol determining module of number is specified, for determining the specified number for offset estimation according to following methods
Symbol：
According to the resolution ratio of offset estimation, the specified number is determined, the resolution ratio of wherein offset estimation is higher, the finger
It is more to determine number.
The third aspect, another embodiment of the application additionally provide a kind of computing device, and it includes memory and processor, its
In, the memory instructs for storage program, and the processor is used to call the programmed instruction stored in the memory, presses
The method for performing any demodulated signal in the embodiment of the present application according to the programmed instruction of acquisition.
Fourth aspect, another embodiment of the application additionally provide a kind of computer-readable storage medium, wherein, the computer is deposited
Storage media is stored with computer executable instructions, and the computer executable instructions are used to make the computer perform the application reality
The method for applying any demodulated signal in example.
In the embodiment of the present application, offset estimation is carried out in frequency domain, and frequency deviation compensation is that the signal after being converted to DSTFT enters
(namely realizing that frequency deviation compensates in frequency domain) of row compensation.Relative to based on the non-coherent demodulation of time domain frequency deviation benefit is carried out in time domain
Repay, have more antijamming capability in the frequency deviation compensation that frequency domain is carried out.Because the embodiment of the present application is without going out and believing in local recovery
The carrier wave of number transmitting terminal with frequency with phase, therefore the application demodulation method is simple, it is also not high to hardware requirement.
Brief description of the drawings
Fig. 1 show the application scenarios schematic diagram of the method for the demodulated signal of the embodiment of the present application offer；
Fig. 2 show the schematic flow sheet of the method for the demodulated signal of the embodiment of the present application offer.
Fig. 3 show the schematic flow sheet that the embodiment of the present application provides renewal energy threshold；
Fig. 4 show the schematic flow sheet of the symbol synchronization of the embodiment of the present application offer；
Fig. 5 show the schematic diagram of the lead code of the embodiment of the present application offer；
Fig. 6 show the offset estimation of the embodiment of the present application offer and the schematic flow sheet of compensation；
Fig. 7 show the structural representation of the device of the demodulated signal of the embodiment of the present application offer；
Fig. 8 show the structural representation that the embodiment of the present application provides computing device.
Embodiment
For the ease of understanding the technical scheme of the embodiment of the present application offer, the application is implemented with reference to Figure of description
Example is described in further detail.
Inventor has found, is obtained after down coversion, modulus sampling and low-pass filtering treatment are carried out to FSK/GFSK signals in zero
Frequency data signal.If the zero intermediate frequency data signal for receiving each symbol in signal carries out DSTFT conversion, conversion knot
Fruit can have a spectral peak at corresponding frequency, and the symbol can be demodulated according to the spectral peak.Such as, 2FSK signals, such as
The base band binary digit that the fruit symbol represents is 1, and in-fd+ Δs f, (wherein, fd is the carrier shift of 2FSK modulation, and Δ f is for it
Send carrier wave relative to local clock frequency shift (FS)) Frequency point at have a spectral peak；If the base band two that the symbol represents
Binary digits are 0, then DSTFT transformation results can have a spectral peak in fd+ Δs f frequency.So, by comparing symbol DSTFT
As a result at-fd+ Δs f and fd+ Δ f frequencies spectral peak size, you can FSK/GFSK signals are demodulated.In view of this, originally
Apply in embodiment, realize that signal demodulates using DSTFT transformation results.
For ease of understanding the technical scheme of the embodiment of the present application offer, with reference first to Fig. 1, provided for the embodiment of the present application
The structural representation of the applicable application scenarios of the method for demodulated signal.In the application scenarios, including terminal 101, the and of base station 102
Server 103.The terminal 101 can be the various equipment of Internet of Things application, such as：Monitoring of environmental situation or the biography for tracking object
Sensor, the meter for measuring water, electricity, gas etc..The base station can wirelessly be communicated with the terminal room.
When it is implemented, terminal can be used as signal sending end to require that base station sends a signal to server 103, base station can
To be sent to server 103 after the signal that terminal is sent is demodulated as signal receiving end.
Terminal 101 and base station 102.Both ends carry out sending and receiving for signal according to agreement.Docked according to agreement base station 102
The signal received is demodulated.
Wherein, due to the presence of noise, the signal that base station 102 does not know when to receive is noise or terminal 101
The useful signal of transmission.So in the embodiment of the present application, the real-time reception signal of base station 102, it is determined that receiving useful signal
Before, the energy of the signal received is detected in real time, and determines whether to receive effective information according to energy.Such as assume to connect
The energy for multiple Baud Length interior energy Baud Lengths that continued access receives is both greater than energy threshold and then determines to receive useful signal, so
After carry out demodulation process.Specifically, during real-time reception signal, following handle is carried out in real time：
Zero intermediate frequency numeral letter is obtained after carrying out down coversion, modulus sampling and low-pass filtering treatment successively to the signal received
Number；
DSTFT conversion, the data signal after being converted are carried out to the zero intermediate frequency data signal；
The data signal after the conversion of a Baud Length is often obtained, calculates the energy of the data signal of the Baud Length,
Energy as a symbol；
If the energy of the symbol of continuous specified quantity exceedes energy threshold, since the specified symbol more than energy threshold
The symbol of specified number is determined, specifies the symbol of number to carry out offset estimation according to this in frequency domain, and be followed by offset estimation
Data signal after the DSTFT conversion of the signal received carries out frequency deviation compensation；
Signal after compensating frequency deviation carries out symbol synchronization, and determines the start bit of symbol received after symbol synchronization
Put；
Since original position, frequency is being specified according to signal of the symbol after DSTFT conversion to each code element
Spectral peak distribution at point, and the corresponding relation of the distribution of default spectral peak and demodulation result, determine the demodulation result of the symbol.
So, in the embodiment of the present application, offset estimation is carried out in frequency domain, and frequency deviation compensation is after being converted to DSTFT
(namely realizing that frequency deviation compensates in frequency domain) that signal compensates.Enter line frequency in time domain relative to the non-coherent demodulation based on time domain
Offset compensation, have more antijamming capability in the frequency deviation compensation that frequency domain is carried out.Because the embodiment of the present application in local recovery without going out
Carrier wave with signal sending end with frequency with phase, therefore the application demodulation method is simple, it is also not high to hardware requirement.
For ease of the more deep scheme for understanding the embodiment of the present application and providing, this is further described below.
Embodiment one
Reference picture 2, for the embodiment of the present application one provide demodulated signal method flow diagram, this method be applied to FSK and/
Or GFSK signal demodulation, this method comprise the following steps：
Step 201：During real-time reception signal, down coversion, modulus are carried out successively to the signal received in real time
Zero intermediate frequency data signal is obtained after sampling and low-pass filtering treatment.
Step 202：Discrete Short Time Fourier DSTFT conversion is carried out to the zero intermediate frequency data signal, after being converted
Data signal.
Wherein, for each sampled point (i.e. each zero intermediate frequency data signal), DSTFT transformation results can use equation below
(1) represent：
Wherein, m is summation variable, and the formula represents once to calculate each sampled point, then accumulation calculating knot
Fruit.X (m) represents the signal value at moment m, and w (n-m) represents the window function value at n-m moment.
Wherein x () is input signal sequence, and w () is mobile window function, and N is window function width, could be arranged to a code
The length of member, n represents current time in X (n, k), and k represents discrete point in frequency, and X (n, k) represents signal at moment n, frequency k
Frequency spectrum.As can be seen from the above equation, DSTFT is actually the discrete Fourier transform for having added mobile window function, and X (n, k) reflects
Investigate the frequency distribution situation at moment.
Step 203：The data signal after the conversion of a Baud Length is often obtained, calculates the data signal of the Baud Length
Energy, the energy as a symbol.
Step 204：If the energy of the symbol of continuous specified quantity exceedes energy threshold, from specifying more than energy threshold
Symbol starts to determine the symbol for specifying number, specifies the symbol of number to carry out offset estimation according to this in frequency domain, and to frequency deviation
Data signal after the DSTFT conversion of the signal received after estimation carries out frequency deviation compensation.
Step 205：Signal after compensating frequency deviation carries out symbol synchronization, and the symbol for determining to receive after symbol synchronization
Original position.
Step 206：Since original position, to signal of each code element according to the symbol after DSTFT conversion
The distribution of the spectral peak at frequency, and the corresponding relation of the distribution of default spectral peak and demodulation result are being specified, is determining the solution of the symbol
Adjust result.
Wherein, 2 binary signals have 2 frequencies as specified frequency (such as foregoing-fd and fd frequencies), the signal of 4 systems
With 4 frequencies, the like.
Wherein, by taking 4 binary signals as an example, the corresponding relation of the distribution of default spectral peak and demodulation result is illustrated.It is false
If it specifies frequency difference fd, 2fd, 3fd, 4fd, then the default spectral peak of 4 binary signals is distributed the corresponding pass with demodulation result
System can be as shown in table 1.It is defined it should be noted that table 1 is merely to illustrate the embodiment of the present application not to this.
Table 1
| Spectral peak frequency | Demodulation result |
| fd | 00 |
| 2fd | 01 |
| 3fd | 10 |
| 4fd | 11 |
Further, energy threshold can be the setting value being pre-configured with.But consider receiver thermal noise, RF device
The interference of part and other wireless communication systems, different receiver bandwidth and operating temperature, different radio-frequency devices, other are wireless
The interference of communication system can cause the bottom of receiver to be made an uproar difference, if energy threshold is set as into a constant value obviously can not
Meet all complex environments.So in the embodiment of the present application, it is contemplated that varying environment different operating condition, not even not simultaneously
Between the bottom of receiver make an uproar difference, using adaptive energy threshold value.During implementation, the energy cut-off can be determined according to following methods
Value, specifically：
It is determined that in the current update cycle energy of symbol minimum value；
According to following energy threshold more new formula (2), energy threshold is updated；
Thadj(i+1)=λ (Thadj(i)+Emin(i)*C) (2)
Wherein, Thadj(i+1) energy threshold after renewal is represented；Thadj(i) energy threshold before renewal is represented；Emin(i)
The minimum value of the energy of symbol in the current update cycle is represented, the set update cycle is more than the duration of useful signal,
To ensure that the minimum value can reflect the size of noise；λ is less than 1, is preset ratio coefficient；C is default renewal coefficient.Specifically
During implementation, the update cycle can determine that the embodiment of the present application is not construed as limiting to this according to actual conditions.
λ value can be 0.5 during specific implementation, naturally it is also possible to which experiment is determined according to the actual requirements, and the application is implemented
Example is not construed as limiting to this.
By taking Fig. 3 as an example, automatically updating for energy threshold in the embodiment of the present application is described further, including following step
Suddenly：
Step 301：Primary power threshold value and renewal coefficient are set.
Step 302：Timing is carried out to the current update cycle by timer, and the energy of the symbol is calculated for each code element
Amount.
Step 303：Determine whether the energy of the symbol is more than energy threshold, if so, then performing step 304；If it is not, then hold
Row step 306.
Step 304：It is determined that continuously whether the quantity more than the symbol of energy threshold is more than specified quantity, if it is not, then returning
Perform step 302；If so, then perform step 305.
Step 305：The flag of frame of the signal received is set to 1, the signal for representing to receive is useful signal.
Step 306：It is determined that continuously whether the quantity less than or equal to the symbol of energy threshold is more than predetermined amount, if it is not, then
Return and perform step 302；If so, then perform step 307.
Step 307：The flag of frame of the signal received is set to 0, the signal for representing to receive is invalid signals.
Step 308：Judge whether current update cycle during timer expires, if it is not, return to step 302；If so, then
Perform step 309.
Wherein, the execution sequence of step 308 is unrestricted.
Step 309：The energy-minimum of symbol in the current update cycle is obtained, and is updated according to energy threshold more new formula
Energy threshold.
Further, in order to preferably realize symbol synchronization, in the embodiment of the present application, signal sending end agreement is sent
Lead code with particular sequence.Specifically, if the signal received is the useful signal that signal sending end is sent, receive
The lead code of signal include the first sub- lead code for symbol synchronization；Wherein, the described first sub- lead code is by full 0 symbol
Composition is alternately arranged with all-ones member；
Signal after the compensation to frequency deviation carries out symbol synchronization, specifically includes following steps A1- steps A：
Step A1：After frequency deviation compensation, determine to proceed by the preliminary starting of symbol synchronization from the described first sub- lead code
Position；And using the symbol where the preliminary original position as current sync symbol, and using the preliminary original position as deserve
The original position of preamble symbols.
Wherein, in first symbol for carrying out symbol synchronization, the preliminary original position is random in respective symbol.
When it is implemented, the position of the signal received after can frequency deviation be compensated proceeds by code as determination in the first sub- lead code
First synchronous preliminary original position, certainly, after the position for the signal that can also be received after frequency deviation is compensated, random selection
One position is as preliminary original position.Preferably, the randomly selected position, is the symbol received after frequency deviation compensation
It is randomly selected in length.When it is implemented, can determine according to the actual requirements, the application is not construed as limiting to this.
When it is implemented, the half that initial synchronisation step-length is a Baud Length is that (N is a symbol length to N/2
Degree)；
Step A2：To deserve the original positions of preamble symbols forward, each mobile current sync step-length backward, moved
Two code elements after step-length.
Step A3：DSTFT conversion is carried out respectively to the two code elements after moving step length.
Step A4：It is big to compare energy of the two code elements after current sync symbol and its moving step length at corresponding frequency
It is small；Wherein, the corresponding frequency of current sync symbol refers to for representing frequency of the symbol for full 0 symbol or all-ones member.
For example, for 2FSK signals, frequency corresponding to full 0 symbol is-fd, and frequency corresponding to all-ones member is fd.
Step A5：In two code elements after current sync symbol and its moving step length, the maximum symbol of energy is selected
Start position of the original position as next symbol.
Step A6：Judge whether current symbol synchronization number reaches specified synchronization times.
When it is implemented, synchronization times are specified to determine according to the actual requirements.
In order to complete symbol synchronization, the quantity of the symbol in the first sub- lead code, which is more than, specifies synchronization times.So,
Even if the processing after the reception or reception of symbol is made a fault, can also there is sufficient amount of symbol to complete symbol synchronization.
Step A7：If so, then terminate symbol synchronization.
Certainly, when it is implemented, in order to which the point of interface of each symbol, i.e., the reality of each symbol is determined more accurately out
Initiation problem, in the embodiment of the present application, after step A 6, the start position that can also record the maximum symbol of the energy is relative
In the skew of preliminary original position.Then, during subsequent demodulation, the original position of symbol received after symbol synchronization is determined, can be had
Body includes：The multiple skews obtained in element synchronization are counted, select the most skew of occurrence number as final
Skew；According to final skew, the original position of symbol received after symbol synchronization is determined.
Because the skew of signal is fixed, the length of symbol is also fixed, so after determining skew, according to symbol
Length be that can determine that the original position of follow-up each symbol.
So, original position is determined according to the most skew of occurrence number, then it is determined that original position it is more accurate
It is really reliable.
Step A8：If it is not, then update current sync step-length according to exponential decrease rule；And using next symbol as current
Returned after sync symbols and perform step A2.
Wherein, it is described to update current sync according to exponential decrease rule if when it is implemented, initial synchronisation step-length is N/2
Step-length, specifically include：
Current sync step-length is updated according to below equation (3)；
λn+1=max (λn/ 2,1) (3)
Wherein, λn+1Represent the current sync step-length after renewal；λnRepresent the current sync step-length before renewal；Represent.
By taking 2FSK signals as an example, as shown in figure 4, for the embodiment of the present application provide symbol synchronization and accurately determine symbol
Original position schematic flow sheet, comprise the following steps：
Step 401：Synchronous step-length is initialized, the maximum times of symbol synchronization are set, are provided for the maximum of symbol synchronization
Synchronization times, the first sub- lead code for being provided for symbol synchronization.
Wherein, 2FSK the first lead code is " 0 " and " 1 " alternating.
By that analogy, 4 system FSK the first lead code is " 00 " and " 11 " alternating.
Wherein, the synchronous step-length λ of initializationinit, such as formula (4)：
λinit=N/2 (4)
Wherein, N is a Baud Length.
Step 402：After frequency deviation compensation, determine to proceed by the preliminary starting of symbol synchronization from the described first sub- lead code
Position；And using the symbol where the preliminary original position as current sync symbol symbol serial number n, and by the preliminary start bit
Put as the original position for deserving preamble symbols.
Step 403：To deserve the original positions of preamble symbols forward, each mobile current sync step-length backward, moved
Two code elements after dynamic step-length.
Step 404：DSTFT conversion is carried out respectively to the two code elements after moving step length.
It is X (n- λ to obtain transformation resultsn, k), X (n+ λn, k), wherein λnFor current sync step-length.
Step 405：Judge whether energy of the current sync symbol at frequency fd is more than the energy at frequency-fd places, if
Step 406 is performed, performs step 407 if not.
Step 406：The position that energy is maximum at fd is selected in two code elements after current sync symbol and its moving step length
Put, as the original position of next symbol, perform step 408 afterwards.
Step 407：The maximum position of energy at selection-fd in two code elements after current sync symbol and its moving step length
Put, as the original position of next symbol, perform step 408 afterwards.
Step 408：Current sync step-length is updated according to exponential decrease rule, and records current sync symbol and preliminary starting
The skew of position.
Step 409：Judge whether current symbol synchronization number reaches specified synchronization times, if so, step 411 is performed,
If it is not, step 410 will be performed.
Step 410：Step 403 is performed using next symbol as return after current sync symbol.
Step 411：The multiple skews obtained in element synchronization are counted, select the most skew of occurrence number
As final skew；According to final skew, the original position of symbol received after symbol synchronization is determined.
The symbol synchronization method provided according to the embodiment of the present application, synchronous step-length is variable step size, and the synchronous step-length is got over
Become smaller, so the determination of synchronization accuracy more and more higher, the original position of subsequent symbol is also more accurate.In addition, for one
Symbol, DSTFT conversion only is carried out to 2 symbols after itself and moving step length, same symbol is for, only performs 3
A symbol synchronization can be achieved in secondary DSTFT.Operand is small.
Further, in the embodiment of the present application, the offset estimation of frequency domain can use prior art to realize.And the application is real
Apply in example, in order to preferably carry out offset estimation and symbol synchronization, also include for offset estimation in the lead code
Second sub- lead code, the first sub- lead code is located at after the second sub- lead code in the lead code；The second sub- lead code
For full 0 symbol or all-ones member.
As shown in figure 5, it is the structural representation of the lead code provided in the embodiment of the present application.Wherein, before a represents the second son
Leading code (lead code i.e. for offset estimation), L1 represent that the length of the second sub- lead code, b represent that the first sub- lead code (is used
In the lead code of symbol synchronization), L2 represent the second sub- lead code length.
When it is implemented, before the signal after compensating frequency deviation carries out symbol synchronization, methods described also includes：According to first
Individual energy is more than the first default number of symbols and the first sub- lead code in the element position of energy threshold, the second sub- lead code
In the second default number of symbols, determine the second sub- lead code for symbol synchronization.For example, 24 codes are shared in lead code
Member, then it can arrange preceding 8 symbols and be used for offset estimation, rear 16 symbols are for symbol synchronization.
Further, following steps B1- steps be may particularly include according to specifying the symbol of number to carry out offset estimation in frequency domain
Rapid B2：
Step B1：The symbol of number is specified to carry out FFT this.
When it is implemented, point of the specified number, wherein offset estimation according to the resolution ratio of offset estimation, can be determined
Resolution is higher, and the specified number is more.
For example, specify minimum frequency space corresponding to the resolution ratio of number N1=data rates/offset estimation.
Step B2：In the frequency spectrum of FFT result, frequency corresponding to spectrum peak position is detected.
Step B3：Frequency and respective standard frequency, determine frequency deviation result according to corresponding to spectrum peak position；Wherein, if
Two sub- lead codes are full 0 symbol, then respective standard frequency is the frequency used for representing full 0 symbol；If the second sub- lead code
For all-ones member, then respective standard frequency is the frequency used for representing all-ones member.
For ease of understanding the frequency deviation estimating method of the embodiment of the present application offer, still by taking 2FSK signals as an example, offset estimation
Method flow diagram as shown in fig. 6, comprising the following steps：
Step 601：Initialize the resolution ratio of offset estimation, the second sub- lead code is set.
Wherein, the second sub- lead code is full 0 symbol or all-ones member.
Step 602：According to the resolution ratio of offset estimation, the number of symbols needed for offset estimation is determined.
Step 603：The symbol of specified number is determined since the specified symbol more than energy threshold, number is specified to this
Symbol carry out FFT.
Step 604：In the frequency spectrum of FFT result, frequency corresponding to spectrum peak position is detected.
Because lead code is full 0, FFT result can have a maximum (i.e. spectral peak) on frequency spectrum, search the maximum
The frequency position f of valuemax.In the case where frequency shift (FS) is 0, frequency corresponding to maximum point should be-fd, and (it sends for signal
The frequency that end and signal receiving end both sides appoint), if frequency shift (FS) is not 0, frequency corresponding to maximum of points can be corresponding
Shift, so can be in the hope of frequency deviation result Δ f, as shown in formula (5)：
Δ f=fmax-fi (5)
Wherein, fmaxRepresent frequency corresponding to spectrum peak position；If the second sub- lead code is full 0 symbol, fiExpression-fd；If the
Two sub- lead codes are that all-ones are first, fiRepresent fd.
Step 605：Frequency deviation compensation is carried out to the DSTFT transformation results of subsequent symbol according to frequency deviation result.
In summary, in the embodiment of the present application, offset estimation, compensation and symbol are realized according to the lead code of particular sequence
It is synchronous.Wherein offset estimation and compensation is carried out in a frequency domain, relative to the irrelevant demodulation method of prior art frequency domain, is resisted dry
Immunity is more preferable, it is possible to increase the accuracy of demodulation result.Relative to coherent demodulation method in the prior art, design is simple, to hard
The requirement of part resource is low.
In addition, in the embodiment of the present application, energy threshold can be updated according to actual conditions, i.e., using adaptive energy
Threshold value carries out energy measuring to signal, and changeable complex environment is can adapt to relative to fixed energies threshold value.
Wherein, the preamble structure based on particular sequence (i.e. comprising the first sub- lead code and the second sub- lead code), combination
The symbol synchronization of variable step, realize low operand, real-time symbol synchronization method.
Embodiment two
Based on identical inventive concept, the embodiment of the present application also provides a kind of device of demodulated signal, applied to frequency displacement key
Signal FSK is controlled, and/or, Gaussian frequency shifted key signal GFSK.The principle and beneficial effect of the device and side described in embodiment one
The principle of method is identical with beneficial effect, repeats no more here.
Referring to Fig. 7, for the structural representation of the device, including
Pretreatment module 701, for during real-time reception signal, being carried out down successively to the signal received in real time
Zero intermediate frequency data signal is obtained after frequency conversion, modulus sampling and low-pass filtering treatment；
DSTFT conversion modules 702, for carrying out Discrete Short Time Fourier DSTFT conversion to the zero intermediate frequency data signal,
Data signal after being converted；
Energy computation module 703, the data signal after conversion for often obtaining a Baud Length, calculate symbol length
The energy of the data signal of degree, the energy as a symbol；
Frequency offset compensation block 704, if the energy for the symbol of continuous specified quantity exceedes energy threshold, from more than energy
The specified symbol of amount threshold value starts to determine the symbol for specifying number, specifies the symbol of number to carry out frequency deviation according to this in frequency domain and estimates
Meter, and the data signal after the DSTFT conversion of the signal to being received after offset estimation carries out frequency deviation compensation；
Symbol synchronization module 705, symbol synchronization is carried out for the signal after compensating frequency deviation, and determine that symbol synchronization is followed by
The original position of the symbol received；
Demodulation module 706, for since original position, being converted to each code element according to the symbol by the DSTFT
Signal afterwards is specifying the distribution of the spectral peak at frequency, and the corresponding relation of the distribution of default spectral peak and demodulation result, it is determined that should
The demodulation result of symbol.
Further, described device also includes：
Adaptive energy threshold determination module, for determining the energy threshold according to following methods：
It is determined that in the current update cycle energy of symbol minimum value；
According to following energy threshold more new formula, energy threshold is updated；
Thadj(i+1)=λ (Thadj(i)+Emin(i)*C)
Wherein, Thadj(i+1) energy threshold after renewal is represented；Thadj(i) energy threshold before renewal is represented；Emin(i)
Represent the minimum value of the energy of symbol in the current update cycle；λ is less than 1, is preset ratio coefficient；C is default renewal coefficient.
Further, if the signal received is the useful signal that signal sending end is sent, before the signal received
Leading code includes the first sub- lead code for symbol synchronization；Wherein, the described first sub- lead code is by full 0 symbol and all-ones member
It is alternately arranged composition；
The symbol synchronization module, is specifically included：
Initial synchronization unit, after compensating for frequency deviation, determine to proceed by symbol synchronization from the described first sub- lead code
Preliminary original position；And using the symbol where the preliminary original position as current sync symbol, and by the preliminary start bit
Put as the original position for deserving preamble symbols；
Mobile unit, for will deserve the original positions of preamble symbols forward, each mobile current sync step-length backward, obtain
Two code elements after to moving step length；
DSTFT converter units, for carrying out DSTFT conversion respectively to the two code elements after moving step length；
Comparing unit, for comparing the energy of current sync symbol and the two code elements after its moving step length at corresponding frequency
Measure size；Wherein, the corresponding frequency of current sync symbol refers to for representing frequency of the symbol for full 0 symbol or all-ones member；
Selecting unit, in the two code elements after current sync symbol and its moving step length, selecting energy maximum
Start position of the original position of symbol as next symbol；
Whether judging unit, the symbol synchronization number for judging current reach specified synchronization times；
Processing unit, if for reaching specified synchronization times, terminate symbol synchronization；If not up to specifying synchronization times,
Then current sync step-length is updated according to exponential decrease rule；And performed next symbol as return after current sync symbol
To deserve the original positions of preamble symbols forward, each mobile current sync step-length backward, obtain two codes after moving step length
The step of member.
Further, the second sub- lead code for offset estimation is also included in the lead code, in the lead code
First sub- lead code is located at after the second sub- lead code；The second sub- lead code is full 0 symbol or all-ones member；
Frequency offset compensation block, specifically include：
FFT unit, for specifying the symbol of number to carry out Fast Fourier Transform (FFT) FFT to this；
Detection unit, in the frequency spectrum of FFT result, detecting frequency corresponding to spectrum peak position；
Frequency deviation result determining unit, for the frequency according to corresponding to spectrum peak position and respective standard frequency, determines frequency deviation
As a result；Wherein, if the second sub- lead code is full 0 symbol, respective standard frequency is the frequency used for representing full 0 symbol；
If the second sub- lead code is all-ones member, respective standard frequency is the frequency used for representing all-ones member.
Further, described device also includes：
Sub- lead code identification module, for symbol synchronization module to frequency deviation compensate after signal carry out symbol synchronization it
Before, according to first energy be more than the first default number of symbols in the element position of energy threshold, the second sub- lead code and
The second default number of symbols in first sub- lead code, determines the second sub- lead code for symbol synchronization.
Further, described device also includes：
Logging modle is offset, in two code elements of the selecting unit after current sync symbol and its moving step length,
After selecting start position of the original position of the maximum symbol of energy as next symbol, the maximum symbol of the energy is recorded
Start position relative to preliminary original position skew；
Symbol synchronization module, is specifically included：
Selecting unit is offset, for being counted to the multiple skews obtained in element synchronization, selects occurrence number
Most skews are as final skew；
Symbol original position determining unit, for the symbol that according to final skew, determines to receive after symbol synchronization
Original position.
Further, initial synchronisation step-length is the half of a Baud Length；
The processing unit, specifically for updating current sync step-length according to below equation；
λn+1=max (λn/ 2,1)
Wherein, λn+1Represent the current sync step-length after renewal；λnRepresent the current sync step-length before renewal；Represent.
Further, described device also includes：
The symbol determining module of number is specified, for determining the specified number for offset estimation according to following methods
Symbol：
According to the resolution ratio of offset estimation, the specified number is determined, the resolution ratio of wherein offset estimation is higher, the finger
It is more to determine number.
Embodiment three
The embodiment of the present application three additionally provides a kind of computing device, and the computing device is specifically as follows desktop computer, just
Take formula computer, smart mobile phone, tablet personal computer, personal digital assistant (Personal Digital Assistant, PDA), clothes
Business device, base station etc..As shown in figure 8, the computing device can include central processing unit (Center Processing Unit,
CPU) 801, memory 802, input equipment 803, output equipment 804 etc., input equipment can include keyboard, mouse, touch-screen
Deng output equipment can include display device, such as liquid crystal display (Liquid Crystal Display, LCD), cathode-ray
Manage (Cathode Ray Tube, CRT) etc..
Memory can include read-only storage (ROM) and random access memory (RAM), and provide storage to processor
The programmed instruction and data stored in device.In the embodiment of the present application, memory can be used for the method for storing demodulated signal
Programmed instruction.By calling the programmed instruction of memory storage, processor is used to perform according to the programmed instruction of acquisition processor：
During real-time reception signal, the signal received is carried out successively in real time at down coversion, modulus sampling and LPF
Zero intermediate frequency data signal is obtained after reason；
Discrete Short Time Fourier DSTFT conversion, the data signal after being converted are carried out to the zero intermediate frequency data signal；
The data signal after the conversion of a Baud Length is often obtained, calculates the energy of the data signal of the Baud Length,
Energy as a symbol；
If the energy of the symbol of continuous specified quantity exceedes energy threshold, since the specified symbol more than energy threshold
The symbol of specified number is determined, specifies the symbol of number to carry out offset estimation according to this in frequency domain, and be followed by offset estimation
Data signal after the DSTFT conversion of the signal received carries out frequency deviation compensation；
Signal after compensating frequency deviation carries out symbol synchronization, and determines the start bit of symbol received after symbol synchronization
Put；
Since original position, frequency is being specified according to signal of the symbol after DSTFT conversion to each code element
Spectral peak distribution at point, and the corresponding relation of the distribution of default spectral peak and demodulation result, determine the demodulation result of the symbol.
Example IV
The embodiment of the present application four provides a kind of computer-readable storage medium, by saving as based on used in above-mentioned computing device
Calculation machine programmed instruction, it includes the program for the method for being used to perform above-mentioned demodulated signal.
The computer-readable storage medium can be any usable medium or data storage device that computer can access, bag
Include but be not limited to magnetic storage (such as floppy disk, hard disk, tape, magneto-optic disk (MO) etc.), optical memory (such as CD, DVD,
BD, HVD etc.) and semiconductor memory (such as it is ROM, EPROM, EEPROM, nonvolatile memory (NAND FLASH), solid
State hard disk (SSD)) etc..
Finally it should be noted that：Above example is only to illustrate the technical scheme of the application, rather than its limitations；Although
The application is described in detail with reference to the foregoing embodiments, it will be understood by those within the art that：It still may be used
To be modified to the technical scheme described in foregoing embodiments, or equivalent substitution is carried out to which part technical characteristic；
And these modification or replace, do not make appropriate technical solution essence depart from each embodiment technical scheme of the application spirit and
Scope.
Claims (16)
- A kind of 1. method of demodulated signal, it is characterised in that applied to frequency shift keyed signals FSK, and/or, GFSK Gaussian Frequency Shift Keying Signal GFSK, methods described include：During real-time reception signal, down coversion, modulus sampling and low pass filtered are carried out successively to the signal received in real time Zero intermediate frequency data signal is obtained after ripple processing；Discrete Short Time Fourier DSTFT conversion, the data signal after being converted are carried out to the zero intermediate frequency data signal；The data signal after the conversion of a Baud Length is often obtained, calculates the energy of the data signal of the Baud Length, as The energy of one symbol；If the energy of the symbol of continuous specified quantity exceedes energy threshold, determined since the specified symbol more than energy threshold Go out the symbol of specified number, specify the symbol of number to carry out offset estimation according to this in frequency domain, and to being received after offset estimation Signal DSTFT conversion after data signal carry out frequency deviation compensation；Signal after compensating frequency deviation carries out symbol synchronization, and determines the original position of symbol received after symbol synchronization；Since original position, each code element is being specified at frequency according to signal of the symbol after DSTFT conversion Spectral peak distribution, and the corresponding relation of the distribution of default spectral peak and demodulation result determines the demodulation result of the symbol.
- 2. according to the method for claim 1, it is characterised in that methods described also includes：The energy threshold is determined according to following methods：It is determined that in the current update cycle energy of symbol minimum value；According to following energy threshold more new formula, energy threshold is updated；Thadj(i+1)=λ (Thadj(i)+Emin(i)*C)Wherein, Thadj(i+1) energy threshold after renewal is represented；Thadj(i) energy threshold before renewal is represented；Emin(i) represent The minimum value of the energy of symbol in the current update cycle；λ is less than 1, is preset ratio coefficient；C is default renewal coefficient.
- 3. according to the method for claim 1, it is characterised in that if the signal received is the effective of signal sending end transmission Signal, the then lead code of the signal received include the first sub- lead code for symbol synchronization；Wherein, before first son Leading code is alternately arranged and formed by full 0 symbol and all-ones member；Signal after the compensation to frequency deviation carries out symbol synchronization, specifically includes：After frequency deviation compensation, determine to proceed by the preliminary original position of symbol synchronization from the described first sub- lead code；And should Symbol where preliminary original position is as current sync symbol, and using the preliminary original position as should preamble symbols Original position；To deserve the original positions of preamble symbols forward, each mobile current sync step-length backward, obtain two after moving step length Individual symbol；DSTFT conversion is carried out respectively to the two code elements after moving step length；Compare energy size of the two code elements after current sync symbol and its moving step length at corresponding frequency；Wherein, currently The corresponding frequency of sync symbols refers to for representing frequency of the symbol for full 0 symbol or all-ones member；In two code elements after current sync symbol and its moving step length, the original position conduct of the maximum symbol of energy is selected The start position of next symbol；Judge whether current symbol synchronization number reaches specified synchronization times；If so, then terminate symbol synchronization；If it is not, then update current sync step-length according to exponential decrease rule；And using next symbol as current sync symbol after Return perform will deserve the original positions of preamble symbols forward, each mobile current sync step-length backward, after obtaining moving step length Two code elements the step of.
- 4. according to the method for claim 3, it is characterised in that also include second for offset estimation in the lead code Sub- lead code, the first sub- lead code is located at after the second sub- lead code in the lead code；The second sub- lead code is full 0 Symbol or all-ones member；It is described that offset estimation is carried out according to the symbol of specified number in frequency domain, specifically include：The symbol of number is specified to carry out Fast Fourier Transform (FFT) FFT this；In the frequency spectrum of FFT result, frequency corresponding to spectrum peak position is detected；Frequency and respective standard frequency, determine frequency deviation result according to corresponding to spectrum peak position；Wherein, if the second sub- lead code is Full 0 symbol, then respective standard frequency is the frequency used for representing full 0 symbol；If the second sub- lead code is all-ones member, Respective standard frequency is the frequency used for representing all-ones member.
- 5. according to the method for claim 4, it is characterised in that before the signal after compensating frequency deviation carries out symbol synchronization, Methods described also includes：According to first energy be more than the first default number of symbols in the element position of energy threshold, the second sub- lead code and The second default number of symbols in first sub- lead code, determines the second sub- lead code for symbol synchronization.
- 6. according to the method for claim 3, it is characterised in that two codes after current sync symbol and its moving step length In member, after selecting start position of the original position of the maximum symbol of energy as next symbol, methods described also includes：The start position of the maximum symbol of the energy is recorded relative to the skew of preliminary original position；The original position of symbol received after symbol synchronization is determined, is specifically included：The multiple skews obtained in element synchronization are counted, select the most skew of occurrence number as finally inclined Move；According to final skew, the original position of symbol received after symbol synchronization is determined.
- 7. according to the method for claim 3, it is characterised in that initial synchronisation step-length be Baud Length two/ One；It is described to update current sync step-length according to exponential decrease rule, specifically include：Current sync step-length is updated according to below equation；λn+1=max (λn/ 2,1)Wherein, λn+1Represent the current sync step-length after renewal；λnRepresent the current sync step-length before renewal；Represent.
- 8. according to the method for claim 4, it is characterised in that methods described also includes：The symbol of the specified number for offset estimation is determined according to following methods：According to the resolution ratio of offset estimation, the specified number is determined, the resolution ratio of wherein offset estimation is higher, described specified Number is more.
- A kind of 9. device of demodulated signal, it is characterised in that applied to frequency shift keyed signals FSK, and/or, GFSK Gaussian Frequency Shift Keying Signal GFSK, described device include：Pretreatment module, for during real-time reception signal, carrying out down coversion, mould successively to the signal received in real time Zero intermediate frequency data signal is obtained after number sampling and low-pass filtering treatment；DSTFT conversion modules, for carrying out Discrete Short Time Fourier DSTFT conversion to the zero intermediate frequency data signal, become Data signal after changing；Energy computation module, the data signal after conversion for often obtaining a Baud Length, calculate the number of the Baud Length The energy of word signal, the energy as a symbol；Frequency offset compensation block, if the energy for the symbol of continuous specified quantity exceedes energy threshold, from more than energy threshold Specified symbol start to determine to specify the symbol of number, specify the symbol of number to carry out offset estimation according to this in frequency domain, and The data signal after DSTFT conversion to the signal received after offset estimation carries out frequency deviation compensation；Symbol synchronization module, symbol synchronization is carried out for the signal after compensating frequency deviation, and determine what is received after symbol synchronization The original position of symbol；Demodulation module, for since original position, to signal of each code element according to the symbol after DSTFT conversion The distribution of the spectral peak at frequency, and the corresponding relation of the distribution of default spectral peak and demodulation result are being specified, is determining the solution of the symbol Adjust result.
- 10. device according to claim 9, it is characterised in that described device also includes：Adaptive energy threshold determination module, for determining the energy threshold according to following methods：It is determined that in the current update cycle energy of symbol minimum value；According to following energy threshold more new formula, energy threshold is updated；Thadj(i+1)=λ (Thadj(i)+Emin(i)*C)Wherein, Thadj(i+1) energy threshold after renewal is represented；Thadj(i) energy threshold before renewal is represented；Emin(i) represent The minimum value of the energy of symbol in the current update cycle；λ is less than 1, is preset ratio coefficient；C is default renewal coefficient.
- 11. device according to claim 9, it is characterised in that if the signal received is having for signal sending end transmission Signal is imitated, then the lead code of the signal received includes the first sub- lead code for symbol synchronization；Wherein, first son Lead code is alternately arranged and formed by full 0 symbol and all-ones member；The symbol synchronization module, is specifically included：Initial synchronization unit, after compensating for frequency deviation, determine to proceed by the first of symbol synchronization from the described first sub- lead code Walk original position；And using the symbol where the preliminary original position as current sync symbol, and the preliminary original position is made To deserve the original position of preamble symbols；Mobile unit, for will deserve the original positions of preamble symbols forward, each mobile current sync step-length backward, moved Two code elements after dynamic step-length；DSTFT converter units, for carrying out DSTFT conversion respectively to the two code elements after moving step length；Comparing unit is big for comparing the energy of current sync symbol and the two code elements after its moving step length at corresponding frequency It is small；Wherein, the corresponding frequency of current sync symbol refers to for representing frequency of the symbol for full 0 symbol or all-ones member；Selecting unit, in the two code elements after current sync symbol and its moving step length, selecting the maximum symbol of energy Start position of the original position as next symbol；Whether judging unit, the symbol synchronization number for judging current reach specified synchronization times；Processing unit, if for reaching specified synchronization times, terminate symbol synchronization；If not up to specifying synchronization times, press Current sync step-length is updated according to exponential decrease rule；And should using next symbol as return execution after current sync symbol The original position of current sync symbol forward, each mobile current sync step-length backward, obtain the two code elements after moving step length Step.
- 12. device according to claim 11, it is characterised in that also include for offset estimation in the lead code Two sub- lead codes, the first sub- lead code is located at after the second sub- lead code in the lead code；The second sub- lead code is Full 0 symbol or all-ones member；Frequency offset compensation block, specifically include：FFT unit, for specifying the symbol of number to carry out Fast Fourier Transform (FFT) FFT to this；Detection unit, in the frequency spectrum of FFT result, detecting frequency corresponding to spectrum peak position；Frequency deviation result determining unit, for the frequency according to corresponding to spectrum peak position and respective standard frequency, determine frequency deviation result； Wherein, if the second sub- lead code is full 0 symbol, respective standard frequency is the frequency used for representing full 0 symbol；If second Sub- lead code is all-ones member, then respective standard frequency is the frequency used for representing all-ones member.
- 13. device according to claim 12, it is characterised in that described device also includes：Sub- lead code identification module, before carrying out symbol synchronization for the signal after symbol synchronization module is compensated frequency deviation, root The first default number of symbols and the first son being more than according to first energy in the element position of energy threshold, the second sub- lead code The second default number of symbols in lead code, determines the second sub- lead code for symbol synchronization.
- 14. device according to claim 11, it is characterised in that, described device also includes：Logging modle is offset, in two code elements of the selecting unit after current sync symbol and its moving step length, selection After start position of the original position of the maximum symbol of energy as next symbol, rising for the maximum symbol of the energy is recorded Put skew of the position relative to preliminary original position；Symbol synchronization module, is specifically included：Selecting unit is offset, for being counted to the multiple skews obtained in element synchronization, selects occurrence number most Skew as final skew；Symbol original position determining unit, for according to final skew, determining the starting of symbol received after symbol synchronization Position.
- 15. device according to claim 11, it is characterised in that initial synchronisation step-length be Baud Length two/ One；The processing unit, specifically for updating current sync step-length according to below equation；λn+1=max (λn/ 2,1)Wherein, λn+1Represent the current sync step-length after renewal；λnRepresent the current sync step-length before renewal；Represent.
- 16. device according to claim 12, it is characterised in that described device also includes：The symbol determining module of number is specified, for determining the code of the specified number for offset estimation according to following methods Member：According to the resolution ratio of offset estimation, the specified number is determined, the resolution ratio of wherein offset estimation is higher, described specified Number is more.
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