CN104301271A - Frequency spectrum conversion method based on polarization rotational angular velocity discretization encoding - Google Patents

Abstract

The invention relates to a frequency spectrum conversion method based on polarization rotational angular velocity discretization encoding. According to the method, different polarization rotational angular velocities are adopted to modulate signals, values of the polarization rotational angular velocities are periodic rectangular pulse functions, main energy of the modulated signals carrying symbol information is distributed at set frequency points, the energy of the modulation signals distributed outside the frequency points is extremely low and will not interfere in other communication systems, and therefore occupation of the signals on frequency spectrum resources is reduced. The different polarization rotational angular velocities are converted into angular velocity Doppler frequency shifts at received ends, so that signal energy is distributed at positions of frequency points deviating from a centre carrier frequency, interference signals not having polarization rotational angular velocities are still located at frequency points of the centre carrier frequency, and therefore the interference signals located at the frequency points of the centre carrier frequency and effective signals deviating from the frequency points of the centre carrier frequency can be effectively distinguished through a band-pass filter, and the interference resistance ability of a communication system can be improved.

Description

A kind of Spectrum Conversion method based on polarized rotation angular speed discretization coding

Technical field

The present invention relates to the communications field, particularly a kind of Spectrum Conversion method based on polarized rotation angular speed discretization coding.

Background technology

Under existing communication system, use electromagnetic spectrum feature representation raw information, various signal madulation mode is adopted to carry out information transmission, the modulation technique wherein adopted comprises amplitude modulation double side band modulation (AM), carrier-suppressed double sideband amplitude-modulating modulation (DSB), AMSSB (Amplitude Modulation Single-Side-Band) modulation (SSB), vestigial sideband amplitudemodulation modulation (VSB), frequency modulation(FM) (FM), phase-modulation (PM), amplitude keying (ASK), frequency keying (FSK), phase keying (PSK, DPSK, QPSK, QAM, MSK), pulse-ampli tude modulation (PAM), pulse-width modulation (PWM), pulse-position modulation (PPM), pulse-code modulation (PCM) and differential pulse code modulation (DPCM) etc.

When adopting above various modulation system to realize information transmission, inromation bandwidth is limited by channel spectral bandwidth, and in order to improve the transmission rate of information system, needs to increase channel width.But along with spacecraft quantity is increasing, spatial frequency spectrum resource day is becoming tight, and unrestrictedly can not increase channel width.

Summary of the invention

The object of the invention is to overcome the deficiencies in the prior art, a kind of Spectrum Conversion method based on polarized rotation angular speed discretization coding is provided, the method adopts different polarized rotation angular speed to modulate signal, and the value of polarized rotation angular speed is Periodic Rectangular impulse function, therefore the Energy distribution of the modulation signal of symbolic information is carried at the frequency place of setting, the energy level being distributed in the modulation signal outside this frequency is low, interference can not be caused to other communication systems, this signal taking frequency spectrum resource can be reduced.

Above-mentioned purpose of the present invention is achieved by following technical solution:

Based on a Spectrum Conversion method for polarized rotation angular speed discretization coding, comprise the following steps:

(1), according to system works centre frequency f ₀generate the single frequency carrier signal S of linear polarization ₀(t), wherein, S ₀(t)=cos (ω ₀t), ω ₀=2 π f ₀;

(2) the N kind symbolic information transmitted, as required determines N number of polarized rotation angular speed, wherein, and the n-th polarized rotation angular speed ‖ ω corresponding with n-th kind of symbolic information _c,nt the computing formula of () ‖ is as follows:

ω _c,n(t)＝ω _o 0≤t≤τ _n

ω _c,n(t)＝0 τ _n<t<τ _n+T _n

Wherein, Δ θ _nfor setting the n-th polarized rotation step angle and 0 ° of < Δ θ _n<360 °; T _nfor the rotation stepping time interval corresponding to the n-th symbolic information of setting, T _n>T ₀; N-th polarized rotation angular speed ‖ ω _c,nt () ‖ is ω _c,nthe periodic extension function of (t), continuation cycle T _n'=τ _n+ T _n; Wherein, n=1,2 ..., N;

(3), in the sending time slots of each symbolic information, the polarized rotation angular speed corresponding according to described symbolic information, adopt the polarized rotation angular speed of discretization to modulate carrier signal, wherein said symbolic information sending time slots length is T _s, concrete modulations achievement is as follows:

If the symbolic information transmitted in described symbolic information sending time slots is n-th kind of symbolic information, then according to the n-th polarized rotation angular speed ‖ ω _c,nt () ‖ modulates carrier signal, obtain the signal after modulating as follows:

S _c,n(t)＝cos(||ω _c,n(t)||·t)·cos(ω _o·t)+j·sin(||ω _c,n(t)||·t)·cos(ω _o·t)；

(4), at symbolic information receiving terminal adopt reception antenna A and reception antenna B to carry out Signal reception respectively, obtain Received signal strength y (t)=y _a(t)+jy _b(t), wherein, y _at () is the Received signal strength of reception antenna A, y _bt () is the Received signal strength of reception antenna B, reception antenna A is horizontal linear polarization antenna, and reception antenna B is vertical line poliarizing antenna;

(5), in each receiving slot, Received signal strength y (t) obtained is received to step (4) and carries out Fourier transform, obtain Received signal strength frequency spectrum Y (w), and described signal spectrum Y (w) is searched for obtain frequency ω corresponding to Amplitude maxima _maxif, described in or the symbolic information then received in described receiving slot is n-th kind of symbolic information.

In the above-mentioned Spectrum Conversion method based on polarized rotation angular speed discretization, in step (3), adopt the polarized rotation angular speed ‖ ω of discretization _c,nt () ‖ is to carrier signal S ₀(t)=cos (ω ₀when t) modulating, produce short electromagnetic pulse interference S _j,n(t), wherein, described impulse disturbances S _j,nthe cycle T of (t) _j,n=τ _n+ T _n, pulse duration τ _j,n=τ _n, pulse amplitude

In the above-mentioned Spectrum Conversion method based on polarized rotation angular speed discretization, corresponding to the rotation stepping time interval T of the n-th symbolic information _n=k _nt ₀, wherein k _nfor positive integer, n=1,2 ..., N.

In the above-mentioned Spectrum Conversion method based on polarized rotation angular speed discretization, described symbolic information sending time slots length is T _smeet following condition: $T_s\&GreaterEqual;\frac{360}{\mathrm{\&Delta;}{\mathrm{\&theta;}}_n}({\mathrm{\&tau;}}_n+T_n),n=\mathrm{1,2},...,N.$

The present invention compared with prior art has following beneficial effect:

(1), the present invention adopts different polarized rotation angular speed to modulate signal, and the value of polarized rotation angular speed is Periodic Rectangular impulse function, therefore the main energetic carrying the modulation signal of symbolic information is distributed in the frequency place of setting, this signal taking frequency spectrum resource can be reduced, under the prerequisite that channel width is constant, improve the transmission rate of communication system, therefore can be used for the passback problem solving low rail high-resolution satellite magnanimity reconnaissance data;

(2), the present invention adopts different polarized rotation angular speed to modulate signal, different polarized rotation angular speed is converted to angular speed Doppler frequency shift at receiving terminal, signal energy is made to concentrate on the frequency place of offset carrier centre frequency, and the polarization characteristic of traditional electronic jamming signal does not change, its angular speed Doppler frequency shift is zero, interference signal is still positioned at centre carrier frequency frequency, therefore band pass filter can be utilized in the present invention effectively to distinguish the useful signal of interference signal and the offset carrier center frequency point being positioned at carrier center frequency, thus improve the antijamming capability of communication system.

Accompanying drawing explanation

Fig. 1 is the Spectrum Conversion method flow diagram based on angular velocity of rotation discretization coding of the present invention;

Fig. 2 is the n-th polarized rotation angular speed ‖ ω that in the present invention, n-th kind of symbolic information is corresponding _c,nthe time domain waveform of (t) ‖;

Fig. 3 is the normalized power spectrum of signal after modulation in the present invention.

Embodiment

Below in conjunction with the drawings and specific embodiments, the present invention is described in further detail:

The present invention utilizes the polarization characteristic of electromagnetic signal to carry out information transmission, wherein often kind of symbolic information sets a polarized rotation angular speed function, namely the polarisation angles modulating rear signal is made to change according to the step angle of setting between 0 ~ 360 degree, thus the main energetic of signal after modulation is concentrated on carrier signal frequency place, and adopt two linear polarized antennas to receive at receiving terminal, different polarized rotation angular speed is converted to angular speed Doppler frequency shift at receiving terminal, make the Energy distribution of signal at the frequency place of offset carrier centre frequency, therefore symbolic information can be demodulated according to this values of Doppler frequency shift.

The inventive method flow chart as shown in Figure 1, the Spectrum Conversion method based on polarized rotation angular speed discretization coding of the present invention comprises the following steps:

(1), according to system works centre frequency f ₀generate the single frequency carrier signal S of linear polarization ₀(t), wherein, S ₀(t)=cos (ω ₀t), ω ₀=2 π f ₀;

(2) the N kind symbolic information transmitted, as required determines N number of polarized rotation angular speed, wherein, and the n-th polarized rotation angular speed ‖ ω corresponding with n-th kind of symbolic information _c,nt the computing formula of () ‖ is as follows:

ω _c,n(t)＝ω _o 0≤t≤τ _n

ω _c,n(t)＝0 τ _n<t<τ _n+T _n

Wherein, Δ θ _nfor setting the n-th polarized rotation step angle and 0 ° of < Δ θ _n<360 °; T _nfor the rotation stepping time interval corresponding to the n-th symbolic information of setting, T _n>T ₀, can preferably this time interval be T _n=k _nt ₀, wherein k _nfor positive integer, optimal value is k _n=1; N-th polarized rotation angular speed ‖ ω _c,nt () ‖ is ω _c,nthe periodic extension function of (t), continuation cycle T _n'=τ _n+ T _n, this polarized rotation angular speed ‖ ω _c,nthe time domain beamformer of (t) ‖ as shown in Figure 2, wherein, n=1,2 ..., N;

(3), in each symbol sending time slots, the polarized rotation angular speed corresponding according to described symbol, adopt the polarized rotation angular speed of discretization to modulate carrier signal, wherein said symbol sending time slots length is T _s, this symbol sending time slots length is T _smeet following condition: it is hereby ensured that the changing value of the polarisation angles of modulation signal in sending time slots interval is greater than 360 degree, namely polarisation angles can rotate a circle above;

Above-described concrete modulations achievement is as follows:

If the symbolic information transmitted in described symbol time slot is n-th kind of symbolic information, then according to the n-th polarized rotation angular speed ‖ ω _c,nt () ‖ modulates carrier signal, obtain the signal after modulating as follows:

S _c,n(t)＝cos(||ω _c,n(t)||·t)·cos(ω _o·t)+j·sin(||ω _c,n(t)||·t)·cos(ω _o·t)；

After modulation as shown in Figure 3, the normalized power spectrum of signal is known, signal S after this modulation _c,nt the main energetic of () is distributed in center frequency point ω ₀place.And in symbolic information sending time slots, signal S _c,nt the polarisation angles of () is according to step angle Δ θ _nchange, namely the value of this polarisation angles is respectively θ ₀, θ ₀+ Δ θ _n, θ ₀+ 2 Δ θ _n..., wherein θ ₀for initial polarization angle.

Short electromagnetic pulse interference S is created in above modulated process _j,n(t), wherein, described impulse disturbances S _j,nthe cycle T of (t) _j,n=τ _n+ T _n, pulse duration τ _j,n=τ _n, pulse amplitude in order to reduce above short electromagnetic pulse interference to the impact of communication system, can according to pulse amplitude and step angle Δ θ _nrelation, select suitable step angle Δ θ _nvalue reduces pulse amplitude, makes this short electromagnetic pulse interference signal can not form interference to other communication systems.。

(4), at symbolic information receiving terminal adopt reception antenna A and reception antenna B to carry out Signal reception respectively, obtain Received signal strength y (t)=y _a(t)+jy _b(t), wherein, y _at () is the Received signal strength of reception antenna A, y _bt () is the Received signal strength of reception antenna B, reception antenna A is horizontal linear polarization antenna, and reception antenna B is vertical line poliarizing antenna;

Receiving terminal adopts two linear polarized antennas to receive, different polarized rotation angular speed is converted to different angular speed Doppler frequency shifts at receiving terminal, make the Energy distribution of signal at the frequency place of offset carrier centre frequency, therefore can demodulate symbolic information according to this values of Doppler frequency shift.

(5), in each receiving slot, Received signal strength y (t) obtained is received to step (4) and carries out Fourier transform, obtain Received signal strength frequency spectrum Y (w), and described signal spectrum Y (w) is searched for obtain frequency ω corresponding to Amplitude maxima _maxif, described in or the symbolic information then received in described receiving slot is n-th kind of symbolic information.

Adopt Spectrum Conversion method of the present invention, the Spectrum Conversion method that multiple carrier frequency carries out above-described polarized rotation angular speed discretization can be chosen in communication band bandwidth, when can guarantee to adopt multiple carrier frequency parallel processing according to the performing step of above invention, can not spectral interference be caused, and can compatible existing communication system.The polarized rotation angle of m user should be greater than 2 π .m2 Δ f _m, wherein 2 Δ f _mit is the communication channel bandwidth of m user.

The above; be only the embodiment of the best of the present invention, but protection scope of the present invention is not limited thereto, is anyly familiar with those skilled in the art in the technical scope that the present invention discloses; the change that can expect easily or replacement, all should be encompassed within protection scope of the present invention.

The content be not described in detail in specification of the present invention belongs to the known technology of professional and technical personnel in the field.

Claims (4)

1., based on a Spectrum Conversion method for polarized rotation angular speed discretization coding, it is characterized in that comprising the following steps:

(1), according to system works centre frequency f ₀generate the single frequency carrier signal S of linear polarization ₀(t), wherein, S ₀(t)=cos (ω ₀t), ω ₀=2 π f ₀;

(2) the N kind symbolic information transmitted, as required determines N number of polarized rotation angular speed, wherein, the n-th polarized rotation angular speed corresponding with n-th kind of symbolic information || ω _c,n(t) || computing formula as follows:

ω _c,n(t)＝ω _o 0≤t≤τ _n

ω _c,n(t)＝0 τ _n<t<τ _n+T _n

Wherein, Δ θ _nfor setting the n-th polarized rotation step angle and 0 ° of < Δ θ _n<360 °; T _nfor the rotation stepping time interval corresponding to the n-th symbolic information of setting, T _n>T ₀; N-th polarized rotation angular speed || ω _c,n(t) || be ω _c,nthe periodic extension function of (t), continuation cycle T _n'=τ _n+ T _n; Wherein, n=1,2 ..., N;

(3), in the sending time slots of each symbolic information, the polarized rotation angular speed corresponding according to described symbolic information, adopt the polarized rotation angular speed of discretization to modulate carrier signal, wherein said symbolic information sending time slots length is T _s, concrete modulations achievement is as follows:

If the symbolic information transmitted in described symbolic information sending time slots is n-th kind of symbolic information, then according to the n-th polarized rotation angular speed || ω _c,n(t) || carrier signal is modulated, obtains the signal after modulating as follows:

S _c,n(t)＝cos(||ω _c,n(t)||·t)·cos(ω _o·t)+j·sin(||ω _c,n(t)||·t)·cos(ω _o·t)；

(4), at symbolic information receiving terminal adopt reception antenna A and reception antenna B to carry out Signal reception respectively, obtain Received signal strength y (t)=y _a(t)+jy _b(t), wherein, y _at () is the Received signal strength of reception antenna A, y _bt () is the Received signal strength of reception antenna B, reception antenna A is horizontal linear polarization antenna, and reception antenna B is vertical line poliarizing antenna;

(5), in each receiving slot, Received signal strength y (t) obtained is received to step (4) and carries out Fourier transform, obtain Received signal strength frequency spectrum Y (w), and described signal spectrum Y (w) is searched for obtain frequency ω corresponding to Amplitude maxima _maxif, described in ${\mathrm{\&omega;}}_{\max }={\mathrm{\&omega;}}_0+\frac{{2\mathrm{\&pi;\&tau;}}_n}{({\mathrm{\&tau;}}_n+T_n)T_0}$ Or ${\mathrm{\&omega;}}_{\max }={\mathrm{\&omega;}}_0-\frac{{2\mathrm{\&pi;\&tau;}}_n}{({\mathrm{\&tau;}}_n+T_n)T_0},$ The symbolic information then received in described receiving slot is n-th kind of symbolic information.

2. a kind of Spectrum Conversion method based on polarized rotation angular speed discretization coding according to claim 1, is characterized in that, in step (3), adopts the polarized rotation angular speed of discretization || ω _c,n(t) || to carrier signal S ₀(t)=cos (ω ₀when t) modulating, produce short electromagnetic pulse interference S _j,n(t), wherein, described impulse disturbances S _j,nthe cycle T of (t) _j,n=τ _n+ T _n, pulse duration τ _j,n=τ _n, pulse amplitude $\left|{\stackrel{\&RightArrow;}{r}}_n\right|=\sqrt{2}\&CenterDot;\sqrt{1-\cos \left({\mathrm{\&Delta;\&theta;}}_n\right)}.$

3. a kind of Spectrum Conversion method based on polarized rotation angular speed discretization coding according to claim 1, is characterized in that, corresponding to the rotation stepping time interval T of the n-th symbolic information _n=k _nt ₀, wherein k _nfor positive integer, n=1,2 ..., N.

4. a kind of Spectrum Conversion method based on polarized rotation angular speed discretization coding according to claim 1, it is characterized in that, described symbolic information sending time slots length is T _smeet following condition: $T_s\&GreaterEqual;\frac{360}{\mathrm{\&Delta;}{\mathrm{\&theta;}}_n}({\mathrm{\&tau;}}_n+T_n),n=\mathrm{1,2},...,N.$