CN105049134B - Method for detecting received signal frequency collision in single channel blind separation of frequency-hopping communication - Google Patents
Method for detecting received signal frequency collision in single channel blind separation of frequency-hopping communication Download PDFInfo
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Abstract
The invention discloses a method for detecting received signal frequency collision in single channel blind separation of frequency-hopping communication. The method comprises the following steps of: firstly, obtaining a time-frequency distribution function X(t, f) of a received signal x(t), further calculating out a valid maximum CRc of the number of wave crests of a time-frequency domain time accumulation function according to the time-frequency distribution function X(t, f) of the received signal x(t), finally, judging whether the received signal x(t) generates frequency collision within each period of time according to the valid maximum CRc of the number of wave crests of the time-frequency domain time accumulation function. In a process of single channel blind separation of frequency-hopping communication, periods of time when each component signal in the received signal generates frequency quadrature and collision can be easily separated through the method, and then, single channel blind separation of frequency-hopping communication can be realized more easily, moreover, the method performs processing based on periods of time, as compared with the methods performing processing based on moment, the method has less computational work.
Description
Technical field
The invention belongs to the communications field, is related to single channel blind separation technology and Hopping frequencies Collision Detection, especially relates to
And in frequency hopping communications single channel blind separation, receive signal frequency collision checking method.
Background technology
Frequency Hopping Signal is the random bounce in a very wide frequency range of modulated signal, and its frequency jitter is advised
Rule is referred to as frequency hopping pattern.As Frequency Hopping Signal is in a very wide frequency range, each discrete frequency in its transmitting procedure, to be kept
The phase coherence of rate carrier wave is relatively difficult, and Frequency Hopping Signal is typically modulated using FSK modes.
Single channel blind separation is to receive signal on a single channel, and in the case where source signal accurately cannot be known,
The process of each source signal is isolated from reception signal.Single channel blind separation is mathematically an ill-conditioning problem, with regard to single-pass
Algorithm in terms of road Blind Signal Separation is broadly divided into：Transform domain filtering, using traditional ICA/BSS methods, Basis Function Method, sparse
Decompose with expression, particle filter, by survivor path facture etc..Wherein, preferable method is particle filter and by survivor path
Facture, but its computation complexity is too high, it is difficult to practice, and both of which is from coding and this level reality of bit
Existing single channel blind separation.
Accordingly, it would be desirable to a kind of make frequency hopping communications single channel blind separation calculate simple, to be easy to practice method.
The content of the invention
For solving above-mentioned technical problem, the present invention receives signal frequency in proposing a kind of frequency hopping communications single channel blind separation
Collision checking method, improves the deficiency of frequency hopping communications single channel blind separation problem, equal by the time-frequency domain that will be received in signal
The time period of aliasing is detected with the time period of Time-domain aliasing frequency domain relative separation respectively and separates process, not only reduces frequency hopping
Computation complexity in communication single channel blind separation problem, also greatly reduces the difficulty that blind signal separation is received in docking, so as to more
Blind source separating is realized easily.
Applicable elements of the invention first are：Source signal in single channel is n separate Frequency Hopping Signal, its hop rate
Respectively v1,v2,……,vn；In detection process, the component signal invariable number and each component in signal x (t) is received
Between signal, the probability of occurrence frequency collision is less than 50%, wherein, the minimum component letter of the maximum component signal of amplitude and amplitude
Number Amplitude Ratio is less than 10；
The detection method of reception signal x (t) frequency hit of the present invention includes：
S1：Reception signal x (t) is chosen after Hamming window g (t), is carried out Short Time Fourier Transform and is obtained described connecing
Time-frequency distributions function X (t, f) of collection of letters x (t), determine the unit of time-frequency distributions function X (t, f) for receiving signal x (t)
Process time Td；
S2：The time domain of time-frequency distributions function X (t, f) for receiving signal x (t) is divided into into some time (i-1) Td
≤ti<iTd, and wherein n is calculated respectively0The time-frequency domain accumulated time of time-frequency distributions function X (t, f) of the individual continuous time period
Function, correspondingly records the time-frequency domain accumulated time function crest number of each time period, and records the time-frequency
Accumulated time function crest number effective maximum in domain is CRc, wherein i be positive integer, n0For positive integer, CRcFor positive even numbers；
S3：According to the effective maximum CR of the time-frequency domain accumulated time function crest numberc, judge the reception signal x
(t) within arbitrary time period, occurrence frequency collision or the collision of non-occurrence frequency.
According to a kind of specific embodiment, the effective maximum CR of time-frequency domain accumulated time function crest number is calculatedc's
Method is：
S21：Extract the time-frequency distributions function X (t of i-th time period for receiving signal x (t)i, f), wherein i's is first
Initial value is 1；
S22：Time-frequency distributions function X (t to the presently described time periodi, f) pretreatment；
S23：Calculate the time-frequency distributions function X (t of presently described time period after pretreatmenti, time-frequency domain time f) tires out
Product function, and detect crest number CR of the time-frequency domain accumulated time function curvei, preserve CRiTo set CR；
S24：Relatively i and n0；I is less than n0, after making i=i+1, perform S21；I is more than or equal to n0, calculate the set CR
In the maximum even element of frequency, and be designated as CRc。
According to a kind of specific embodiment, judge that reception signal x (t) within arbitrary time period, occurs frequency
Rate is collided or the method for non-occurrence frequency collision is：
S31：Extract the time-frequency distributions function X (t of time period to be detectedj, f), and pretreatment is carried out to which, wherein j is for just
Integer；
S32：Calculate the time-frequency distributions function X (t of the time period to be detectedj, time-frequency domain accumulated time function f), and
Detect crest number CR of the time-frequency domain accumulated time function curvej；
S33：Relatively CRjAnd CRc；CRjLess than CRc, then the occurrence frequency collision within the time period to be detected, otherwise,
Non- occurrence frequency collision in the time period to be detected.
According to a kind of specific embodiment, the method for the pretreatment is：
S41：Extract time period to be pre-treated upper arbitrary Frequency point fh, its corresponding time-frequency point set is { (ti,fh)|(i-
1)Td≤ti<iTd, wherein time frequency point (t, fh) be the time-frequency point set arbitrary element；
S42：If time frequency point (t, the fh) meet：
X(t,fh)≥αmax{X(ti,fh)|(i-1)Td≤ti<iTd}
(t, f are made thenh)∈Οh；
S43：If | Οh|<β|{(ti,fh)|(i-1)Td≤ti<iTd|, then make the time-frequency distributions function of the time-frequency point set
{X(ti,fh)|(i-1)Td≤ti<iTdIt is zero.Wherein, | | the element number of set, α are asked in expression, β be coefficient factor and
α,β∈[0,1]。
According to a kind of specific embodiment, the per unit processing time TdExpression formula be：
Wherein () represents and asks greatest common divisor, fsFor sample frequency.
According to a kind of specific embodiment, based on the effective maximum of the time-frequency domain accumulated time function crest number
CRc, number n of the source signal in estimation single channel is CRc1/2nd.
According to a kind of specific embodiment, the expression formula of the time-frequency domain accumulated time function is：
Wherein, | X ((i-1) Td+ t, f) | the modulus value of the time-frequency distributions function is sought in expression.
Beneficial effect of the present invention is：Solving component signal component frequency collision in frequency hopping communications single-pass channel receiving signal
Blind separation problem during, can detect that reception signal has Hopping frequencies in which time period and touches with the method for the present invention
Hit, so as to easily separate frequency orthogonal and collision time section, and then more easily realize blind point of frequency hopping communications single channel
From.
As the present invention was processed based on the time period, compare and processed based on the moment, its amount of calculation is less.And drawing
The effective maximum CR of time-frequency domain accumulated time function crest numbercWhile, also indirect Estimation goes out in single-pass channel receiving signal and divides
The number (i.e. the number of source signal) of amount signal.
Description of the drawings
Fig. 1 is the schematic flow diagram of frequency hit detection method of the present invention；
Fig. 2 is that the present invention estimates the effective maximum CR of time-frequency domain accumulated time function crest numbercFlow chart；
Fig. 3 is determination frequency collision or orthogonal flow chart in frequency hit detection method of the present invention.
Specific embodiment
It is described in detail below in conjunction with the accompanying drawings.
Applicable elements of the invention first are：Source signal in single channel is n separate Frequency Hopping Signal, and
Can be calculated to a nicety its hop rate, and each Frequency Hopping Signal is respectively v1,v2,……,vn.In detection process, signal x (t) is received
Between interior component signal invariable number and each component signal, the probability of occurrence frequency collision is less than 50%, wherein, amplitude
The minimum component signal Amplitude Ratio of maximum component signal and amplitude is less than 10.
The schematic flow diagram of the frequency hit detection method of the present invention with reference to shown in Fig. 1；Reception signal x (t) of the present invention
The detection method of frequency hit includes：
S1：After Hamming window g (t) is chosen in docking collection of letters x (t), carry out Short Time Fourier Transform and obtain receiving signal x
T time-frequency distributions function X (t, f) of (), it is determined that receive the per unit processing time T of time-frequency distributions function X (t, f) of signal x (t)d。
Specifically, carry out the expression formula of time-frequency distributions function X (t, f) that Short Time Fourier Transform obtains receiving signal x (t)
For：
After time-frequency distributions function X (t, f) for receiving signal x (t) are obtained, it is thus necessary to determine that its per unit processing time Td。
Per unit processing time TdExpression formula be：
Wherein, () represents and asks greatest common divisor, fsFor sample frequency, due to TdSetting be related to the accuracy of detection,
Therefore the applicable elements of the present invention are required to calculate to a nicety the hop rate of each Frequency Hopping Signal.
S2：The time domain for receiving time-frequency distributions function X (t, f) of signal x (t) is divided into into some time (i-1) Td≤ti<
iTd, and n therein is calculated respectively0The time-frequency domain accumulated time function of time-frequency distributions function X (t, f) of individual continuous time period,
The time-frequency domain accumulated time function crest number of each time period is correspondingly recorded, and records time-frequency domain accumulated time function crest
The effective maximum of number is CRc, wherein i be positive integer, n0For positive integer, CRcFor positive even numbers.
Specifically, n0Can be arranged according to practice, n0It is bigger, time-frequency domain accumulated time function crest number is had
Effect maximum CRcEstimation it is more accurate.But while n0With increase, operand also correspondingly increases.
S3：According to the effective maximum CR of time-frequency domain accumulated time function crest numberc, judge to receive signal x (t) arbitrary
In time period, occurrence frequency collision or non-occurrence frequency are collided.
The present invention with reference to shown in Fig. 2 estimates the effective maximum CR of time-frequency domain accumulated time function crest numbercFlow process
Figure.
Specifically, S21：Extract the time-frequency distributions function X (t of i-th time period for receiving signal x (t)i, f), wherein i's
Initial value is 1；
S22：Time-frequency distributions function X (t to current sloti, f) pretreatment.
S23：Calculate the time-frequency distributions function X (t of current slot after pretreatmenti, time-frequency domain accumulated time letter f)
Number, and detect crest number CR of time-frequency domain accumulated time function curvei, preserve CRiTo set CR.
Specifically, the expression formula of time-frequency domain accumulated time function is：
Wherein, | X ((i-1) Td+t,F) | the modulus value of the time-frequency distributions function is sought in expression.
S24：Relatively i and n0；If i is less than n0, then, after i=i+1 is made, perform S21；If i is more than or equal to n0, meter
The maximum even element of frequency in set CR is calculated, and is designated as CRc。
Determination frequency collision or orthogonal flow chart in frequency hit detection method of the present invention with reference to shown in Fig. 3.
Judge that reception signal x (t) is interior over any time period, the method for occurrence frequency collision or the collision of non-occurrence frequency
For：
S31：Extract the time-frequency distributions function X (t of time period to be detectedj, f), and pretreatment is carried out to which, wherein j is for just
Integer；
S32：Calculate the time-frequency distributions function X (t of time period to be detectedj, time-frequency domain accumulated time function f), and detect
Crest number CR of time-frequency domain accumulated time function curvej；
S33：Relatively CRjAnd CRc；If CRjLess than CRc, then the occurrence frequency collision within the time period to be detected, otherwise,
Non- occurrence frequency collision in time period to be detected.
In the present invention, due to utilizing Short Time Fourier Transform, time-frequency distributions are asked for, on frequency hopping pattern medium frequency saltus step border
On frequency translation occurs.Frequency translation part can form interference crest in cumulative function, therefore relate in S22 and S31
Need to carry out pretreatment to time-frequency distributions function X (t, f) of time period, it is intended to suppress the generation of this interference crest.It is concrete pre-
The method of process is：
S41：Extract time period to be pre-treated upper arbitrary Frequency point fh, its corresponding time-frequency point set is
{(ti,fh)|(i-1)Td≤ti<iTd, wherein time frequency point (t, fh) for time-frequency point set arbitrary element；
S42：If time frequency point (t, fh) meet：
X(t,fh)≥αmax{X(ti,fh)|(i-1)Td≤ti<iTd}
(t, f are made thenh)∈Οh；
S43：If | Οh|<β|{(ti,fh)|(i-1)Td≤ti<iTd|, then make the time-frequency distributions function { X of time-frequency point set
(ti,fh)|(i-1)Td≤ti<iTdIt is zero.Wherein, | | the element number of set, α are asked in expression, and β is coefficient factor and α, β
∈[0,1]。
With reference to one embodiment, the present invention will be described.
There are 3 tunnel source Frequency Hopping Signals in single channel, its hop rate is respectively 250hops/s, 500hops/s, 1000hops/s,
Hopping frequencies sequence be respectively [3MHz, 5.5MHz, 7MHz, 8MHz, 4.5MHz], [3MHz, 9MHz, 5MHz, 7MHz, 4MHz],
[3MHz, 5MHz, 6MHz, 8MHz, 4MHz], 3 road source signal linear hybrid, obtains the reception signal of a length of 1s all the way.
Now realize that detection receives which time period occurrence frequency in signal is collided only by reception signal.The docking collection of letters number
With 20MHz frequency samplings, 4 × 10 are selected4Long Hamming window, carries out Short Time Fourier Transform, obtains time-frequency domain distribution.It is determined that single
Position process time segment length is 1ms, calculates 100 time period cumulative functions that 100ms receives signal length, calculates its crest number
Mesh, obtains CR collection and is combined into
Wherein, 6 frequency for 70,4 frequency for 25,2 frequency be 5.Time-frequency domain accumulated time function crest number has
Effect maximum CRcFor 6.The reception signal of 1s length is detected, the accumulated time function wave peak number mesh of each time period is calculated,
And respectively and CRcValue compares size, so as to the time period for detecting occurrence frequency collision is：
0ms～2ms, 9ms～11ms, 13ms～14ms, 19ms～22ms, 29ms～31ms, 33ms～34ms,
39ms～42ms, 49ms～51ms, 53ms～54ms, 59ms～62ms, 69ms～71ms, 73ms～74ms,
..., 973ms～974ms, 979ms～982ms, 989ms～991ms, 993ms～994ms, 999ms～1000ms
Meanwhile, the present invention is also based on the effective maximum CR of time-frequency domain accumulated time function crest numberc, estimate single-pass
Number n of the source signal in road is CRc1/2nd, i.e., in the present embodiment, CRcIt is worth for 6, source signal is 3 tunnels.
During the blind separation for solving the problems, such as the collision of component signal component frequency in frequency hopping communications single-pass channel receiving signal,
Can detect that reception signal has Hopping frequencies collision in which time period with the method for the present invention, so as to easily will frequency
Rate is orthogonal and collision time section separates, and then more easily realizes frequency hopping communications single channel blind separation.
As the present invention was processed based on the time period, compare and processed based on the moment, its amount of calculation is less.And drawing
The effective maximum CR of time-frequency domain accumulated time function crest numbercWhile, also indirect Estimation goes out in single-pass channel receiving signal and divides
The number (i.e. the number of source signal) of amount signal.
It should be noted that above-mentioned specific embodiment is exemplary, those skilled in the art can be disclosed in the present invention
Various solutions are found out under the inspiration of content, and these solutions also belong to disclosure of the invention scope and fall into this
Within bright protection domain.It will be understood by those skilled in the art that description of the invention and its accompanying drawing be it is illustrative and not
Constitute limitations on claims.Protection scope of the present invention is limited by claim and its equivalent.
Claims (7)
1. signal frequency collision checking method is received in a kind of frequency hopping communications single channel blind separation, it is characterised in that in single channel
In source signal be the separate Frequency Hopping Signals of n, its hop rate is respectively v1, v2... ... vn；In detection process, letter is received
Between component signal invariable number and each component signal in number x (t), the probability of occurrence frequency collision is less than 50%, its
In, the minimum component signal Amplitude Ratio of the maximum component signal of amplitude and amplitude is less than 10；
The detection method for receiving signal x (t) frequency hit includes：
S1：Reception signal x (t) is chosen after Hamming window g (t), carries out Short Time Fourier Transform and obtain described reception believing
Time-frequency distributions function X (t, f) of number x (t), determine the processed in units of time-frequency distributions function X (t, f) for receiving signal x (t)
Time Td；
S2：The time domain of time-frequency distributions function X (t, f) for receiving signal x (t) is divided into into some time (i-1) Td≤ti<
iTd, and wherein n is calculated respectively0The time-frequency domain accumulated time function of time-frequency distributions function X (t, f) of the individual continuous time period,
The time-frequency domain accumulated time function crest number of each time period is correspondingly recorded, and records the time-frequency domain time
The effective maximum of cumulative function crest number is CRc, wherein i be positive integer, n0For positive integer, CRcFor positive even numbers；
S3：According to the effective maximum CR of the time-frequency domain accumulated time function crest numberc, judge that reception signal x (t) exists
In arbitrary time period, occurrence frequency collision or non-occurrence frequency are collided.
2. signal frequency collision checking method is received in frequency hopping communications single channel blind separation according to claim 1, and which is special
Levy and be, calculate the effective maximum CR of time-frequency domain accumulated time function crest numbercMethod be：
S21：Extract the time-frequency distributions function X (t of i-th time period for receiving signal x (t)i, f), the wherein initial value of i is
1；
S22：Time-frequency distributions function X (t to the presently described time periodi, f) pretreatment；
S23：Calculate the time-frequency distributions function X (t of presently described time period after pretreatmenti, time-frequency domain accumulated time letter f)
Number, and detect crest number CR of the time-frequency domain accumulated time function curvei, preserve CRiTo set CR；
S24：Relatively i and n0；I is less than n0, after making i=i+1, perform S21；I is more than or equal to n0, calculate in the set CR
The maximum even element of frequency, and it is designated as CRc。
3. signal frequency collision checking method is received in frequency hopping communications single channel blind separation according to claim 1, and which is special
Levy and be, judge reception signal x (t) within arbitrary time period, occurrence frequency collision or the collision of non-occurrence frequency
Method be：
S31：Extract the time-frequency distributions function X (t of time period to be detectedj, f), and pretreatment is carried out to which, wherein j is positive integer；
S32：Calculate the time-frequency distributions function X (t of the time period to be detectedj, time-frequency domain accumulated time function f), and detect institute
State crest number CR of time-frequency domain accumulated time function curvej；
S33：Relatively CRjAnd CRc；CRjLess than CRc, then the occurrence frequency collision within the time period to be detected, otherwise, described
Non- occurrence frequency collision in time period to be detected.
4. signal frequency collision checking method is received in the frequency hopping communications single channel blind separation according to Claims 2 or 3, its
It is characterised by, the method for the pretreatment is：
S41：Extract time period to be pre-treated upper arbitrary Frequency point fh, its corresponding time-frequency point set is { (ti,fh)|(i-1)Td≤
ti<iTd, wherein time frequency point (t, fh) be the time-frequency point set arbitrary element；
S42：If time frequency point (t, the fh) meet：
X(t,fh)≥αmax{X(ti,fh)|(i-1)Td≤ti<iTd}
(t, f are made thenh)∈Οh；
S43：If | Οh|<β|{(ti,fh)|(i-1)Td≤ti<iTd|, then make the time-frequency distributions function { X of the time-frequency point set
(ti,fh)|(i-1)Td≤ti<iTdIt is zero；Wherein, | | the element number of set, α are asked in expression, and β is coefficient factor and α, β
∈[0,1]。
5. signal frequency collision checking method is received in frequency hopping communications single channel blind separation according to claim 1, and which is special
Levy and be, the per unit processing time TdExpression formula be：
Wherein () represents and asks greatest common divisor, fsFor sample frequency.
6. signal frequency collision checking method is received in frequency hopping communications single channel blind separation according to claim 1, and which is special
Levy and be, based on the time-frequency domain accumulated time function crest number maximum CRc, the number of the source signal in estimation single channel
N is CRc1/2nd.
7. signal frequency side collision detection is received in the frequency hopping communications single channel blind separation according to one of claims 1 to 3
Method, it is characterised in that the expression formula of the time-frequency domain accumulated time function is：
Wherein, | X ((i-1) Td+ t, f) | the modulus value of the time-frequency distributions function is sought in expression.
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