CN102546501A - Multivariate position random polar MCP-EBPSK (Multivariate Continuous Phase-Extended Binary Phase Shift Keying) modulation and demodulation method - Google Patents

Abstract

The invention discloses a multivariate position random polar MCP-EBPSK (Multivariate Continuous Phase-Extended Binary Phase Shift Keying) modulation and demodulation method, which is based on a corrected random polar continuous phase-extended binary phase shift keying modulation mode. The method involves a multivariate position random polar MCP-EBPSK modulator and a multivariate position random polar MCP-EBPSK signal demodulator. The multivariate position random polar MCP-EBPSK modulator is used for carrying out corrected random polar continuous phase keying to different phase modulation periods of sine wave carriers according to multivariate information symbols; and the multivariate position random polar MCP-EBPSK signal demodulator comprises an impulse filter used for highlighting the phase modulation information of received signals and eliminating the polar change of the received signals so that the demodulation performance is not influenced by the modulation of the multivariate position random polar. In the invention, the transmission rate and the spectrum utilization rate of a random polar CP-EBPSK communication system are multiplied by modulation signals, and the system has narrow occupied bandwidth, wide code rate application range, good demodulation performance and good flexibility for use.

Description

Multielement positional is polarity MCP-EBPSK modulation and demodulation method at random

Technical field

The present invention relates to the information modulation and demodulation in the digital communication, particularly a kind of multielement positional is the MCP-EBPSK modulation and demodulation method of polarity at random, belongs to the technical field of high spectrum utilization digital information transmission.

Background technology

The broadband wireless business demand of rapid growth has proposed increasingly high requirement to radio communication; Directly caused aerial radio frequency more and more crowded; Particularly along with the third generation (3G) and the 4th generation (4G) wide-band mobile communication networks development, almost exhausted than the continuous frequency spectrum of low-frequency range.Europe 10MHz frequency spectrum 20 years usufructuary auction prices are up to 4,000,000,000, and in China, spend also to be hard to buy best frequency and bandwidth.Therefore, the same with the energy and water resources, frequency spectrum also is the grand strategy resource of country, compresses the wireless transmission frequency spectrum to greatest extent and has important and practical meanings and direct economic benefit.And, will improve the availability of frequency spectrum (examining) as far as possible with bps/Hz for high-speed transfer information in the unit frequency band, this has become the core competitiveness indicator and the crucial common technology of generation information transmission system.

1, CP-EBPSK modulation

In order to tighten frequency spectrum; We once invented a kind of " binary phase shift keying of continuous phase expansion " (CP-EBPSK:Continue Phase-Extended Binary Phase Shift Keying) modulation and (saw " the extended binary phase shift keying modulation and demodulation method of frequency spectrum compression "; The invention patent mandate notification number: CN101582868B), its uniform expression is:

s ₀(t)＝sinω _ct， 0≤t＜T

$s_1\left(t\right)=\left\{\begin{array}{cc}\sin ({\mathrm{\&omega;}}_{c}t\&PlusMinus;\mathrm{\&Delta;}\sin {\mathrm{\&omega;}}_{c}t),& 0\&le;t<\mathrm{\&tau;},0<\mathrm{\&Delta;}<1\\ \sin {\mathrm{\&omega;}}_{c}t,& 0<\mathrm{\&tau;}\&le;t<T\end{array}\right.---\left(1\right)$

Wherein, s ₀(t) and s ₁(t) represent the modulation waveform of code element " 0 " and " 1 " respectively, ω _cBe the angular frequency of modulated carrier, 0＜Δ＜1 is a phase-modulation index.It is thus clear that code-element period T=2 π N/ ω _cContinued N>=1 carrier cycle, the modulation period of " 1 " code element has continued K＜N carrier cycle, and K and N are integer to guarantee modulation complete cycle.

Visible by (1) formula, the CP-EBPSK modulation waveform has following characteristics:

1) phase place is continuous, and time waveform is also continuous;

2) angular frequency of data " 0 " is ω _c, the angular frequency of data " 1 " is ω _c± Δ ω _cCos ω _cT (signal phase ω _cT ± Δ ω _cSin ω _cT is for the derivative of time t), instantaneous frequency is changed to ± Δ ω _c, be a finite value, the frequency spectrum of CP-EBPSK modulated wave is expected to obtain to tighten when Δ＜＜1;

3) if get the modulation that τ=T can realize the single carrier cycle, thereby the highest code check numerically just equals carrier frequency, and it is the wideest that bandwidth reaches.Along with the reducing of modulation duty cycle τ/T=K/N (or modulation index Δ reduce); Then on certain power spectrum density (PSD:Power Spectrum Density) level, the bandwidth of the modulated waveform of CP-EBPSK can be tending towards so-called ultra arrowband (UNB:Ultra Narrow Band) always.

For example, in (1) formula, get Δ=0.01, N=16, K=2, f _c=ω _c/ 2 π=40kHz, the time waveform that obtains the CP-EBPSK modulation signal is compared its time waveform with the sinusoidal signal (line of dots among Fig. 1 (a)) of standard shown in Fig. 1 (a) solid line, and the signal waveform of visible CP-EBPSK modulation is very near sinusoidal wave.Fig. 1 (b) is the power spectrum of CP-EBPSK modulation signal, and wherein ordinate is that power spectrum amplitude with the carrier frequency place is as 0dB.Visible by Fig. 1 (b), when Δ＜＜1, the energy height of CP-EBPSK modulation signal is concentrated, and carrier frequency (being positioned at the 40kHz place) amplitude is higher than the about 70dB of other sideband (1 thousands of times).

Concrete realization then is: when modulator input symbols " 0 ", modulator is just selected s ₀(t) the waveform sample output shown in, on the contrary when being input as code element " 1 ", modulator is selected s ₁(t) the waveform sample output shown in, the phase-modulation index Δ of all code elements " 1 " institute corresponding modulating waveform all equates, and remains unchanged.

2, the CP-EBPSK of polarity modulation at random

Because the phase-modulation index Δ is big more, good more for the demodulation performance of CP-EBPSK modulation signal, so the selection of Δ is often can not value too little because of compromise the simultaneously availability of frequency spectrum and capacity usage ratio of needs.For example, in order to obtain high code check, we get f _c(this moment, code check was f for=30MHz, N=4 _c/ N=30/N=7.5Mbps), K=2 and Δ=0.1 carried out emulation, this moment the CP-EBPSK modulation signal power spectrum shown in Fig. 2 (a), abscissa is a frequency among the figure; The MHz of unit; Ordinate is a relative amplitude, and the dB of unit has got 10,000 code elements during the rated output spectrum.It is thus clear that the power spectrum sideband of CP-EBPSK modulation signal just fails to reach the requirement of stricter being lower than-60dB at this moment, mainly be because contain higher discrete spectrum (being line spectrum) component in the sideband.Therefore, if can remove or reduce the line spectrum in the CP-EBPSK modulation signal power spectrum sideband, promptly be expected further to reduce the sidebands levels of CP-EBPSK modulation signal power spectrum.

Notice the keying modulation period of CP-EBPSK in each code element " 1 "; (1) the phase-modulation index Δ in the formula or remain unchanged; Staggered reindexing (promptly+Δ or-Δ), this regularity is the basic reason that produces line spectrum component (corresponding the cycle sinusoidal component of time domain) in the PSD sideband.And if when sending code element " 1 "; Let the phase-modulation index Δ symbol (being polarity of modulation) change at random (promptly get at random+Δ or-Δ); Just be expected to reduce or eliminate the sideband line spectrum; Thereby further tighten the power spectrum of CP-EBPSK modulation signal, reduce interference, improve the availability of frequency spectrum adjacent channel.So, we proposed again a kind of " communication system and the communication means thereof of the CP-EBPSK of pseudo random sequence modulation " (application for a patent for invention number: 201110092668.X), through in original CP-EBPSK modulator, increasing a pseudo-random sequence generator; The polarity (being the positive and negative of symbol) of utilizing the pseudo random number of its generation to come the picked at random Δ, promptly in (1) formula, constant for the modulation of data " 0 "; And for data " 1 "; Then investigate the value of the current random number of this pseudo random sequence,, then get+Δ in (1) formula if this value is 0; If this value is 1, then get-Δ in (1) formula; Thereby utilize the randomness of code element " 1 " keying modulation period phase change to remove the most of line spectrum on CP-EBPSK modulation signal PSD main lobe and the secondary lobe; Make the frequency spectrum of modulated signal tighten more (surpassing 20dB shown in Fig. 2 (b)); To its can be like a cork with harsh more-the 60dB power bandwidth is examined, and demodulation performance is unaffected basically.

3, MPPSK modulation

In the pulse modulation application such as radar system and pulse ultra-broad band (IR-UWB) communication system of classics; Usually adopt pulsion phase to transmit different symbolic information, like pulse position modulation (PPM:PulsePosition Modulation) for the difference of carrier position.We once utilized this point; Invented " multielement positional phase shift keying (MPPSK:M-ary Position Phase Shift Keying) modulation and demodulation method " (patent of invention number: ZL200710025202.1); Utilize the out of phase saltus step position of multiple information symbol offset of sinusoidal carrier wave to carry out phase shift keying; Thereby binary phase shift keying (the EBPSK:Extended Binary Phase Shift Keying) modulator approach (being that the ZL200710025203.6 patent that we invented before this is a special case of " unified binary quadrature modulation demodulation method ") of expansion the multi-system modulation and demodulation have been extended to; Under the almost constant condition of spectrum structure and transmitting power, the transmission code rate and the availability of frequency spectrum have doubled.

4, the demodulation of EBPSK modulation signal

Demodulation about the EBPSK modulation signal; We are at application for a patent for invention " a kind of demodulation method that is used for unified binary modulating signal " (application number: 200810124475.6; Publication number: CN101316252); Once disclose a kind of infinite impulse response (IIR) filter of digital zero group delay, be used for giving prominence to the phase hit of EBPSK modulation signal.This digital zero group delay filter is made up of a pair of conjugation zero point and a pair of conjugate pole; Zero frequency is lower than pole frequency; The signal carrier frequency is located between zero frequency and the pole frequency; Promptly be positioned near the intersection point of filter amplitude frequency curve and phase frequency curve, make the output of said modulation signal through filter produce overshoot phenomenon at the phase modulated place to utilize its transient response, and zero frequency and pole frequency be not inferior to 10 of carrier frequency near degree ^-2The order of magnitude.

(the application number: 200910029875.3 that " is used to strengthen the impact filtering method of asymmetric binary modulating signal "; Near publication number: CN101599754) through original limit of digital zero group delay filter, increasing one or more pairs of conjugate poles at least again; Obtained higher overshoot amplitude and better demodulation performance, impacted filter so be referred to as numeral.

Summary of the invention

For continuing to improve the spectrum structure of polarity CP-EBPSK modulation signal at random; (note is made MCP-EBPSK to the object of the present invention is to provide a kind of CP-EBPSK of correction; Be Modified CP-EBPSK) modulator approach; And it is extended to the MCP-EBPSK of the polarity at random modulation and demodulation method of multi-system, to improve the transmission code rate and the availability of frequency spectrum of polarity CP-EBPSK communication system at random exponentially.

For solving the problems of the technologies described above, realize above-mentioned technique effect, the present invention realizes through following technical scheme:

A kind of multielement positional is polarity MCP-EBPSK modulation and demodulation method at random, and step comprises:

1, optimizes the power spectrum shape of polarity CP-EBPSK modulation signal at random and promote demodulation performance.

Visible from Fig. 1 (b) and Fig. 2, the CP-EBPSK modulation has produced the 2nd higher secondary lobe of specific power spectrum main lobe with polarity CP-EBPSK modulation signal at random at 2 frequency multiplication places of carrier frequency, influenced the further deflation of signal bandwidth, has also disperseed the energy of signal.Its reason mainly is the modulation rate of signal phase too fast.For this reason; The present invention at first introduces one less than 1 power spectrum shape adjustment coefficient η (being the CP-EBPSK of the polarity at random modulation signal that does not add correction when the η=1) in the expression formula of polarity CP-EBPSK modulation signal at random, thereby obtains the expression formula of the MCP-EBPSK of the polarity at random modulation system shown in (2) formula:

s ₀(t)＝sinω _ct， 0≤t＜NT _c

$s_1\left(t\right)=\left\{\begin{array}{cc}\sin ({\mathrm{\&omega;}}_{c}t+\mathrm{\&xi;}\&CenterDot;\mathrm{\&Delta;}\sin \left(\mathrm{\&eta;}{\mathrm{\&omega;}}_{c}t\right)),& 0\&le;t<{\mathrm{KT}}_c\\ \sin {\mathrm{\&omega;}}_{c}t,& 0<{\mathrm{KT}}_c\&le;t<{\mathrm{NT}}_c\end{array}\right.---\left(2\right)$

Wherein, T _c=2 π/ω _cBe carrier cycle, ξ ∈ 1,1} has determined the polarity of phase place Stochastic Modulation, and η ∈ (0,1] be the power spectrum shape adjustment coefficient that MCP-EBPSK modulation is introduced.The implication of other variable is identical with (1) formula.

The power spectrum of η=1,1/2,1/3,1/4 and 1/5 the MCP-EBPSK of polarity at random modulation signal under the equal conditions that Fig. 3 (a)～Fig. 3 (e) is contrasted, we can see the trend that the PSD energy is concentrated to carrier frequency and main lobe really.This is very natural, because when η=0, (2) formula just deteriorates to the sine wave of standard.100,000 code elements and 2 have been chosen during the power spectrum of calculating chart 3 ²⁶The fast Fourier transform (FFT) of point is to guarantee high as far as possible precision and resolution.

And from shown in Figure 4 these 5 kinds at random the demodulation performance of polarity MCP-EBPSK modulation signal to recently seeing; When η＜1; Because the energy of polarity MCP-EBPSK modulation signal is concentrated towards its carrier frequency and PSD main lobe more at random, the result has obtained better bit error rate performance.Especially it is maximum to improve amplitude with the demodulation performance of η=1/2 o'clock, for example in Fig. 4 when signal to noise ratio snr=32dB, the demodulation bit error rate of the MCP-EBPSK of the polarity at random modulation of η=1/2 is modulated than the CP-EBPSK of polarity at random of η=1 and has been reduced nearly 2 one magnitude.

2, polarity MCP-EBPSK modulator approach is extended to multi-system by binary system at random.

With reference to the thinking of aforementioned MPPSK, modulate expression formula to the MCP-EBPSK of polarity at random by the definition of (2) formula, expand the multielement positional MCP-EBPSK modulation system of polarity at random shown in (3) formula:

$s_k\left(t\right)=\left\{\begin{array}{ccc}\sin {\mathrm{\&omega;}}_{c}t,& 0\&le;t<{\mathrm{NT}}_c,& k=0\\ \left\{\begin{array}{c}\sin {\mathrm{\&omega;}}_{c}t,\\ \sin ({\mathrm{\&omega;}}_{c}t+\mathrm{\&xi;}\&CenterDot;\mathrm{\&Delta;}\sin \left(\mathrm{\&eta;}{\mathrm{\&omega;}}_{c}t\right)),\\ \sin {\mathrm{\&omega;}}_{c}t,\end{array}\right.& \begin{array}{c}0\&le;t\&le;(k-1){\mathrm{KT}}_c,\\ (k-1){\mathrm{KT}}_c<t<(k-r_g){\mathrm{KT}}_c,\\ (k-r_g){\mathrm{KT}}_c\&le;t<{\mathrm{NT}}_c,\end{array}& \begin{array}{c}\\ 1\&le;k\&le;M-1\\ \end{array}\end{array}\right.---\left(3\right)$

Wherein, k=0,1 ..., M-1 is a M binary information symbol, and M＞2 kind of different value is arranged; 0≤r _g＜1 is symbol protection interval controlling elements.By M, K, N, η, Δ and r _gConstituted one group " modulation parameter " changing signal bandwidth, efficiency of transmission and demodulation performance.

As M=2 and r _g=0 o'clock, (3) formula just deteriorated to (2) formula.

From the power spectrum of the quaternary CP-EBPSK modulation signal of polarity contrast at random shown in polarity CP-EBPSK modulation signal and Fig. 5 (b) at random shown in Fig. 5 (a); Compare from the power spectrum of the quaternary MCP-EBPSK modulation signal of the polarity at random of η=1/2 shown in the MCP-EBPSK modulation signal of polarity at random of η=1/2 shown in Fig. 5 (c) and Fig. 5 (d); After we can see that introducing multi-system modulates; Polarity CP-EBPSK modulation signal and the power spectrum shape of polarity MCP-EBPSK modulation signal is constant basically at random at random, but the line spectrum component has obviously reduced.

3, to multielement positional at random the impact filtering response of polarity MCP-EBPSK modulation signal carry out the multichannel judgement and realize demodulation.

The multielement positional receiver of polarity MCP-EBPSK modulation signal at random still at first adopts the digital filter that impacts that the phase of input signals modulation is converted into the parasitic amplitude modulation of exporting signal, is aided with multichannel adaptive threshold judgement detection again and realizes the demodulation of polarity MCP-EBPSK modulation signal at random of said multielement positional.And said numeral impact filter is a kind of special iir filter; In extremely narrow pass band width, present trap-selecting frequency characteristic; Phase hit small in the modulation signal is converted into the impact on the amplitude; Thereby given prominence to the different wave shape on the amplitude output signal, helped realizing the demodulation of phase-modulated signal through threshold judgement.

Visible from the demodulation bit error rate contrast of the quaternary MCP-EBPSK modulation signal of the polarity at random of the CP-EBPSK of polarity at random shown in Figure 6 modulation, quaternary CP-EBPSK modulation and η=1/2; Under the same error rate, the required signal to noise ratio (snr) of the quaternary of the polarity at random MCP-EBPSK modulation signal of demodulation η=1/2 is minimum on the contrary.This is to waste the line spectrum component of transmitting power and make the result that the power spectrum energy is concentrated more owing to having removed major part.The more important thing is, with the CP-EBPSK chopping phase of polarity at random relatively because the quaternary of the polarity at random MCP-EBPSK of η=1/2 modulation makes the transmission bit rate multiplication, (be E so transmit the required signal to noise ratio of each data _b/ N ₀) reduced half.

We's ratio juris is explained as follows:

Be the basis with the MCP-EBPSK modulation system of polarity at random, the MCP-EBPSK modulation system of said polarity is at random expressed as (2) formula, expands to multi-system to (2) formula from binary system, and its expression formula is shown in (3) formula.By M, K, N, η, Δ and r _gConstituted one group " modulation parameter " changing signal bandwidth, efficiency of transmission and demodulation performance.

The multielement positional MCP-EBPSK modulator of polarity at random comprises a pseudo-random sequence generator; Utilize that it produces have only-1 with+1 two kind maybe value pseudo random number ξ control the symbol of Δ, i.e. the phase modulated polarity of non-" 0 " data in (2) formula or (3) formula.Multielement positional is engraved in the position that occurs in each non-" 0 " code-element period when the MCP-EBPSK modulator of polarity adopts M binary information symbol directly to control the phase hit of sinusoidal carrier through (3) formula at random.The multielement positional MCP-EBPSK modulator introducing power spectrum shape adjustment coefficient η of polarity is at random regulated the shape of modulated signal power spectrum and is promoted demodulation performance.

The multielement positional MCP-EBPSK demodulator of polarity at random comprises a numeral impact filter, is used for giving prominence to the phase modulation information that receives signal and eliminating its change in polarity, makes demodulation performance not receive the influence of phase modulated polarity change at random.It is a kind of infinite impulse response band pass filter that said numeral is impacted filter; Constitute with at least one pair of conjugate pole zero point by a pair of conjugation; Zero frequency is lower than pole frequency; The signal carrier frequency is higher than the zero frequency of impact filtering device but is lower than all pole frequencies, and zero frequency and pole frequency near degree, should not be inferior to 10 of signal carrier frequency ^-2～10 ^-3Magnitude makes said modulation signal produce overshoot phenomenon at the phase modulated place through the output of filter to utilize its transient response.The multielement positional MCP-EBPSK demodulator of polarity at random utilizes numeral impact filter that said multi-system signal code is exported envelope in amplitude and locational difference, adopts the multichannel decision method to realize the demodulation of M system symbol.

The present invention has following beneficial effect:

1) availability of frequency spectrum significantly promotes.Because the CP-EBPSK modulation system is continuous in keying period phase change; Adopt the modulation of polar keying at random to reduce the height of line spectrum in the power spectrum signal significantly; So the very bandwidth that modulation signal takies is narrow; Has the very high availability of frequency spectrum, more near traditional " ultra arrowband ".Introduce the shape that power spectrum shape adjustment coefficient η has optimized power spectrum again; Not only make and in a code-element period, can transmit the more information symbol and introduce the multi-system modulation; The rate of information throughput significantly improves but also has reduced the quantity of line spectrum; Thereby the very bandwidth of modulation signal is narrow, and the availability of frequency spectrum is greatly improved.

2) capacity usage ratio significantly promotes.Because the influence that the impact filtering device can make demodulator not reversed at random by signal phase modulation polarity; Also since power spectrum shape adjustment coefficient η can force down carrier wave 2 frequency multiplication places secondary lobe height (for example when η＜1/2), or make its to carrier frequency near (for example when η=1/2); Make that the energy of modulation signal is more concentrated, thereby the demodulation performance of system is able to also promote.Again because to same sinusoidal carrier; It is identical to adopt the multi-system of polarity at random MCP-EBPSK modulation of the present invention and employing existing polarity binary system CP-EBPSK at random as a comparison to modulate resulting modulation signal power; But institute's information transmitted bit rate significantly improves; Thereby under the situation of no intersymbol interference, transmitting the required signal to noise ratio of each data is E _b/ N ₀Also reduce at double, capacity usage ratio significantly promotes.

3) application is wide.Aerial frequency spectrum is rare natural resources; And efficient modulation-demo-demodulation method of the present invention has reduced taking of frequency spectrum resource from bottom; Be more suitable for adopting cognitive radio (Cognitive Radio; CR) thought further realizes that dynamic spectrum inserts to occupy with static arrowband combines, and makes good use of public resource from top layer, is particluarly suitable for applications such as various limited bandwidth channels such as digital sound radio, digital handset, power line carrier, plastic fiber and brings into play its advantage.

Above-mentioned explanation only is the general introduction of technical scheme of the present invention, understands technological means of the present invention in order can more to know, and can implement according to the content of specification, below with preferred embodiment of the present invention and conjunction with figs. specify as after.Embodiment of the present invention is provided by following examples and accompanying drawing thereof in detail.

Description of drawings

Fig. 1 (a) is the sinusoidal signal of standard and the time waveform contrast of CP-EBPSK modulation signal, and Fig. 1 (b) is the power spectrum of CP-EBPSK modulation signal.

Fig. 2 is the power spectrum signal contrast of CP-EBPSK modulation and polarity CP-EBPSK modulation at random when Δ=0.1, and wherein Fig. 2 (a) is the power spectrum of CP-EBPSK modulation signal, and Fig. 2 (b) is the power spectrum of polarity CP-EBPSK modulation signal at random.Abscissa is a frequency among the figure, and unit is MHz, and ordinate is a relative amplitude, and unit is dB, has chosen 10,000 code elements during the rated output spectrum.

Fig. 3 be when carrier frequency be that 21.4MHz, sample frequency are 214MHz, Δ=0.1, K: N=2: 10, the power spectrum of the MCP-EBPSK modulation signal of polarity at random, abscissa is a frequency among the figure, unit is MHz, ordinate is a relative amplitude, unit is dB.Wherein, Fig. 3 (a) is that η=1 is the power spectrum of the uncorrected CP-EBPSK of polarity at random modulation signal; Fig. 3 (b) is the power spectrum of the MCP-EBPSK of the polarity at random modulation signal of η=1/2; Fig. 3 (c) is the power spectrum of the MCP-EBPSK of the polarity at random modulation signal of η=1/3; Fig. 3 (d) is the power spectrum of the MCP-EBPSK of the polarity at random modulation signal of η=1/4; Fig. 3 (e) is the power spectrum of the MCP-EBPSK of the polarity at random modulation signal of η=1/5.

Fig. 4 is to 5 kinds of demodulation performance contrasts of polarity MCP-EBPSK modulation signal at random shown in Figure 3.

Fig. 5 be when carrier frequency be that 21.4MHz, sample frequency are 214MHz, Δ=0.1, K: N=2: 10, the power spectrum contrast of polarity CP-EBPSK modulation signal at random of 3 kinds during M=4, chosen 100,000 code elements and 2 during the rated output spectrum ²⁶Point FFT, abscissa is a frequency among the figure, and unit is MHz, and ordinate is a relative amplitude, and unit is dB.Wherein, Fig. 5 (a) contrasts and Fig. 2 (a) of redrawing for ease, i.e. the power spectrum of CP-EBPSK modulation signal; Fig. 5 (b) is the power spectrum of quaternary CP-EBPSK modulation signal; Fig. 5 (c) contrasts and Fig. 3 (a) of redrawing for ease, i.e. the power spectrum of the uncorrected CP-EBPSK of the polarity at random modulation signal of η=1; Fig. 5 (d) is the power spectrum of the quaternary CP-EBPSK modulation signal of polarity at random; Fig. 5 (e) contrasts and Fig. 3 (b) of redrawing for ease, i.e. the power spectrum of the MCP-EBPSK of the polarity at random modulation signal of η=1/2; Fig. 5 (f) is the power spectrum of quaternary MCP-EBPSK modulation signal of the polarity at random of η=1/2.

Fig. 6 is polarity CP-EBPSK modulation at random, quaternary CP-EBPSK modulates and the error rate contrast of the quaternary MCP-EBPSK modulation signal of the polarity at random of η=1/2, and modulation parameter is Δ=0.1, K: N=2: 10, M=4.

Fig. 7 is the multielement positional circuit realization block diagram of the MCP-EBPSK modulator of polarity at random.

Fig. 8 is the quaternary of the polarity at random MCP-EBPSK modulation signal time domain waveform example of η=1/2, and modulation parameter is Δ=0.1, K: N=2: 10, M=4.Abscissa is represented sampling number, ordinate expression signal amplitude.

Fig. 9 is the power spectrum of the quaternary of the polarity at random MCP-EBPSK modulation signal of η=1/2, and at the bandwidth at-70.88dB place 31.694kHz only, the availability of frequency spectrum was up to 135bps/Hz when bit rate was about 4.28Mbps.

Figure 10 be based on multielement positional that numeral impacts the judgement of filter multichannel at random the circuit of polarity MCP-EBPSK demodulator realize block diagram.

Figure 11 is based on the given numeral of the present invention and impacts filter coefficient, and the ber curve of the quaternary of the polarity at random MCP-EBPSK modulation signal of demodulation η=1/2 that emulation obtains does not all adopt chnnel coding.

Embodiment

Below with reference to accompanying drawing and combine embodiment, specify the present invention.

1, the multielement positional MCP-EBPSK modulator of polarity at random

Fig. 7 is the realization block diagram of the multi-system MCP-EBPSK signal modulator of said polarity at random; Said modulator comprises a pseudo-random sequence generator, a waveform sample memory module, a clock generator; A digital to analog converter (DAC) also has an alternative digital filter.Its course of work is following:

1) said pseudo-random sequence generator utilizes that it produces have only-1 with+1 two kind maybe value pseudo random number ξ ∈ { 1,1} controls the symbol of phase-modulation index Δ, i.e. the phase modulated polarity of non-" 0 " data in (2) formula or (3) formula.

2) said waveform sample memory module possesses the function of read-only memory (ROM) and MUX (MUX) simultaneously, has stored the modulation signal S shown in (3) formula _k(t) waveform sample, (please noting that different wave shape is very little) as shown in Figure 8.Under the beat control of the clock pulse that said clock generator produced, select the corresponding modulation waveform sample jointly by the multi-system information symbol sequence of input and the output of said pseudo-random sequence generator.

3) when " 0 " code element in the transmission multi-system information sequence, directly select modulation waveform sample S ₀(t) export, needn't consider the output valve of said pseudo-random sequence generator; And when sending non-" 0 " code element, then must { 1, the value of 1} be selected phase-modulation index+Δ and the-pairing modulation waveform of Δ, has promptly directly accomplished computing " ξ Δ " according to pseudo random number ξ ∈ that pseudo-random sequence generator produced.

4) the selected corresponding modulation waveform sample that goes out is sent into said DAC again after said digital filter filtering, has promptly converted the multi-system of the polarity at random MCP-EBPSK modulation signal output of simulation to.

5) since multielement positional of the present invention at random the power spectrum secondary lobe of polarity MCP-EBPSK modulation signal force down significantly (for example in Fig. 9, be lower than-70dB), so usually no longer need the digital filtering link among Fig. 7.

In order to provide availability of frequency spectrum index intuitively; According to FCC (FCC) harsh-the 60dB bandwidth criteria; To the multielement positional of the CP-EBPSK modulation of the modulation of polarity CP-EBPSK at random, multi-system and η=1/2 at random polarity CP-EBPSK modulation carried out-60dB bandwidth and availability of frequency spectrum statistics, the result is shown in table 1 and table 2.Signal carrier frequency in the table is 21.4MHz, and when N=30, the bit rate of CP-EBPSK modulation is about 713.3kbps, and the bit rate of quaternary CP-EBPSK modulation is about 1.426Mbps.It is thus clear that under all situations, the availability of frequency spectrum has all surpassed 230bps/Hz, far above used modulation system

During table 1 K=2 3 kinds of modulation systems-contrast of 60dB bandwidth and the availability of frequency spectrum

During table 2 N=30 3 kinds of modulation systems-contrast of 60dB bandwidth and the availability of frequency spectrum

2, the multielement positional MCP-EBPSK demodulator of polarity at random

Figure 10 is the said multielement positional realization block diagram of the MCP-EBPSK demodulator of polarity at random, and said demodulator comprises an analog to digital converter (ADC), a digital impact filtering device, an envelope detector, M-1 integration decision device and a multiplexer.Its course of work is following:

1) multielement positional of the said ADC simulation that will receive at random the MCP-EBPSK modulation signal of polarity (generally having down-converted to intermediate-freuqncy signal) convert into and give numeral after the digital signal and impact filter.

2) said numeral impact filter is a kind of special IIR type digital band-pass filter; Constitute with at least one pair of conjugate pole zero point by a pair of conjugation; The multielement positional carrier frequency of the MCP-EBPSK modulation signal of polarity at random is higher than the zero frequency of impact filtering device but is lower than all pole frequencies; And zero frequency and pole frequency near degree, to reach 10 of signal carrier frequency at least ^-2～10 ^-3Magnitude.The transfer function of common digital iir filter can be write as following form:

$H\left(z\right)=\frac{\underset{j=0}{\overset{J}{\mathrm{\&Sigma;}}}{b}_j\&CenterDot;z^{-j}}{1-\underset{i=1}{\overset{I}{\mathrm{\&Sigma;}}}{a}_i\&CenterDot;z^{-i}}=\frac{1+\underset{j=1}{\overset{J}{\mathrm{\&Sigma;}}}{b}_j\&CenterDot;z^{-j}}{1-\underset{i=1}{\overset{I}{\mathrm{\&Sigma;}}}{a}_i\&CenterDot;z^{-i}}---\left(4\right)$

A wherein ₀=b ₀=1, z is the Z-transformation domain variable, b _jBe conjugation zero point, a _iBe conjugate pole.Again because numeral is impacted filter by constituting at a pair of conjugation zero point and at least one pair of conjugate pole, so 2=J≤I in (4) formula.

To the multielement positional of η=1/2 polarity MCP-EBPSK modulation signal at random, present embodiment utilization search has automatically obtained following impact filtering device design result:

0. 1 pairs of conjugate poles of 1 pair of conjugation:

b ₁＝-1.618640351773825，b ₂＝1；

a ₁＝-1.449036912558672，a ₂＝0.802018791906955。

0. 2 pairs of conjugate poles of 1 pair of conjugation:

b ₁＝-1.618995687176257，b ₂＝1；

a ₁＝-1.817361012430280，a ₂＝1.436763412570941，a ₃＝-0.513559435879943，a ₄＝0.079854429688135。

0. 3 pairs of conjugate poles of 1 pair of conjugation:

b ₁＝-1.618495523346314，b ₂＝1；

a ₁＝-1.973401307621458，a ₂＝1.707892238042286，a ₃＝-0.700903759306155，a ₄＝0.130496898023677，a ₅＝-0.002568125322230，a ₆＝0.000019814679492。

0. 4 pairs of conjugate poles of 1 pair of conjugation:

b ₁＝-1.618291601965442，b ₂＝1；

a ₁＝-2.168053222193768，a ₂＝2.187962929169438，a ₃＝-1.299383678361045，a ₄＝0.492378155435954，a ₅＝-0.120711291984894，a ₆＝0.018620887125597。a ₇＝-0.001643075331654，a ₈＝0.000066921767388。

0. 5 pairs of conjugate poles of 1 pair of conjugation:

b ₁＝-1.618170608461342，b ₂＝1；

a ₁＝-1.939474919995603，a ₂＝1.681237455829215，a ₃＝-0.732433281562777，a ₄＝0.188918888567184，a ₅＝-0.030731478479574，a ₆＝0.003265945453330，a ₇＝-0.000226833477136，a ₈＝0.000010064787649，a ₉＝-0.000000262232114，a ₁₀＝0.000000003180191。

3) carry out LPF again after the output signal of said envelope detector impact filter takes absolute value; Be used for outstandingly receiving the phase modulation information of signal and eliminating its change in polarity thereby cooperate, make demodulation performance not receive the influence of pseudo random sequence phase modulated with the impact filtering device.

4) utilize numeral to impact filter said signal is exported envelope in amplitude and locational difference, adopt the multichannel decision method to realize the demodulation of M binary information symbol.Shown in figure 10; The impact filtering signal envelope of said envelope detector output is divided into the M-1 road carries out the integration judgement respectively; (1≤m≤M-1) the road decision device only is responsible for distinguishing symbol " m " to m; Promptly only the position that code-element period internal symbol " m " possibly occur near to the sample of signal integration after foundation " thresholding m " adjudicate; To distinguish symbol " m " and symbol " 0 " (want under the control of lock-out pulse on the throne certainly, and omitted the common practise of this this area of bit synchronization DISCHARGE PULSES EXTRACTION among Figure 10).In other words, multielement positional of the present invention at random the MCP-EBPSK demodulator of polarity utilize the amplitude of impact filtering output signal envelope to distinguish symbol " m " and symbol " 0 "; Each non-" 0 " information symbol is distinguished in the position (with respect to the time delay of symbol " 1 ") that utilizes symbol " m " in code-element period, to occur.And for sprocket bit " 1 ", we can make the pairing system duration of symbol " 1 " simply is K ₁Be slightly larger than other M-2 the pairing system duration of non-" 0 " information symbol K.For example when K=2, get K ₁Be 3 or 4, pass through impact filtering and envelope detection like this after, the pairing impact amplitude of symbol " 1 " can obviously surpass the amplitude of other M-1 symbol (comprising symbol " 0 ").

5) utilize described multiplexer that M-1 road court verdict is merged output; Promptly obtain the demodulation result (if the input signal of M-1 road decision device does not all surpass the threshold value of response, then last demodulation result just judgement is symbol " 0 ") of final M binary information sequence.Because when not having intersymbol interference, the judgement on each road output result is non-overlapping copies in time, thereby the output of said multiplexer is exactly M-1 road decision device output result's stack.

Based on the above numeral that designs impact filter coefficient to the quaternary at random the MCP-EBPSK modulator-demodulator of polarity carried out emulation; Obtained ber curve shown in figure 11; Show the digital filter demodulation performance that adopts 0. 3 pairs of conjugate poles of 1 pair of conjugation best (situation that surpasses 3 pairs of conjugate poles is not drawn), and operand is moderate.

The above is merely the preferred embodiments of the present invention, is not limited to the present invention, and for a person skilled in the art, the present invention can have various changes and variation.All within spirit of the present invention and principle, any modification of being done, be equal to replacement, improvement etc., all should be included within protection scope of the present invention.

Claims (5)

1. multielement positional polarity MCP-EBPSK modulation and demodulation method at random is characterized in that step comprises:

1) optimizes the power spectrum shape of polarity CP-EBPSK modulation signal at random and promote demodulation performance.

The uniform expression of CP-EBPSK modulation is:

s ₀(t)＝sinω _ct， 0≤t＜T

$s_1\left(t\right)=\left\{\begin{array}{cc}\sin ({\mathrm{\&omega;}}_{c}t\&PlusMinus;\mathrm{\&Delta;}\sin {\mathrm{\&omega;}}_{c}t),& 0\&le;t<\mathrm{\&tau;},0<\mathrm{\&Delta;}<1\\ \sin {\mathrm{\&omega;}}_{c}t,& 0<\mathrm{\&tau;}\&le;t<T\end{array}\right.---\left(1\right)$

Wherein, s ₀(t) and s ₁(t) represent the modulation waveform of code element " 0 " and " 1 " respectively, ω _cBe the angular frequency of modulated carrier, 0＜Δ＜1 is a phase-modulation index; It is thus clear that code-element period T=2 π N/ ω _cContinued N>=1 carrier cycle, the modulation period of " 1 " code element has continued K＜N carrier cycle, and K and N are integer to guarantee modulation complete cycle;

In expression formula (1), introduce one less than 1 power spectrum shape adjustment coefficient η, when η=1, do not add the CP-EBPSK of the polarity at random modulation signal of correction, thereby obtain the expression formula of the MCP-EBPSK of the polarity at random modulation system shown in (2) formula:

s ₀(t)＝sinω _ct，0≤t＜NT _c

$s_1\left(t\right)=\left\{\begin{array}{cc}\sin ({\mathrm{\&omega;}}_{c}t+\mathrm{\&xi;}\&CenterDot;\mathrm{\&Delta;}\sin \left(\mathrm{\&eta;}{\mathrm{\&omega;}}_{c}t\right)),& 0\&le;t<{\mathrm{KT}}_c\\ \sin {\mathrm{\&omega;}}_{c}t,& 0<{\mathrm{KT}}_c\&le;t<{\mathrm{NT}}_c\end{array}\right.---\left(2\right)$

Wherein, T _c=2 π/ω _cBe carrier cycle, ξ ∈ 1,1} has determined the polarity of phase place Stochastic Modulation, and η ∈ (0,1] be the power spectrum shape adjustment coefficient that the MCP-EBPSK modulation is introduced, the implication of other variable is identical with (1) formula;

2) polarity MCP-EBPSK modulation system is extended to multi-system by binary system at random:

The MCP-EBPSK of polarity at random modulation expression formula, expand the multielement positional MCP-EBPSK modulation system of polarity at random shown in (3) formula by (2) formula definition:

$s_k\left(t\right)=\left\{\begin{array}{ccc}\sin {\mathrm{\&omega;}}_{c}t,& 0\&le;t<{\mathrm{NT}}_c,& k={\mathrm{KT}}_c,0\\ \left\{\begin{array}{c}\sin {\mathrm{\&omega;}}_{c}t,\\ \sin ({\mathrm{\&omega;}}_{c}t+\mathrm{\&xi;}\&CenterDot;\mathrm{\&Delta;}\sin \left(\mathrm{\&eta;}{\mathrm{\&omega;}}_{c}t\right)),\\ \sin {\mathrm{\&omega;}}_{c}t,\end{array}\right.& \begin{array}{c}0\&le;t\&le;(k-1)\\ (k-1){\mathrm{KT}}_c<t<(k-r_g){\mathrm{KT}}_c,\\ (k-r_g){\mathrm{KT}}_c\&le;t<{\mathrm{NT}}_c,\end{array}& \begin{array}{c}\\ 1\&le;k\&le;M-1\\ \end{array}\end{array}\right.---\left(3\right)$

Wherein, k=0,1 ..., M-1 is a M binary information symbol, and M＞2 kind of different value is arranged; 0≤r _g＜1 is symbol protection interval controlling elements; By M, K, N, η, Δ and r _gConstituted one group " modulation parameter " changing signal bandwidth, efficiency of transmission and demodulation performance; As M=2 and r _g=0 o'clock, (3) formula just deteriorated to (2) formula;

3) to multielement positional at random the impact filtering response of polarity MCP-EBPSK modulation signal carry out the multichannel judgement and realize demodulation:

To the multielement positional that the receives MCP-EBPSK modulation signal of polarity at random, at first adopt numeral to impact the phase modulated that filter will receive signal and be converted into the parasitic amplitude modulation of exporting signal; Be aided with multichannel adaptive threshold judgement detection again and realize the demodulation of polarity MCP-EBPSK modulation signal at random of said multielement positional.

2. multielement positional according to claim 1 is polarity MCP-EBPSK modulation and demodulation method at random; It is characterized in that realizing the multi-system MCP-EBPSK signal modulator of the polarity at random of this modulator approach; Comprise a pseudo-random sequence generator; A waveform sample memory module, a clock generator and a digital to analog converter DAC, the course of work of this modulator is following:

A1) pseudo-random sequence generator utilizes that it produces have only-1 with+1 two kind maybe value pseudo random number ξ ∈ { 1,1} controls the symbol of phase-modulation index Δ, i.e. the phase modulated polarity of non-" 0 " data in (2) formula or (3) formula.

A2) the waveform sample memory module possesses the function of read-only memory and MUX simultaneously, has stored the modulation signal S shown in (3) formula _k(t) waveform sample; Under the beat control of the clock pulse that clock generator produced, select the corresponding modulation waveform sample jointly by the multi-system information symbol sequence of input and the output of said pseudo-random sequence generator;

A3) when " 0 " code element in the transmission multi-system information sequence, directly select modulation waveform sample S ₀(t) output; And when sending non-" 0 " code element, then must { 1, the value of 1} be selected phase-modulation index+Δ and the-pairing modulation waveform of Δ, has promptly directly accomplished computing " ξ Δ " according to pseudo random number ξ ∈ that pseudo-random sequence generator produced;

A4) the selected corresponding modulation waveform sample that goes out is sent into said DAC, has promptly converted the multi-system of the polarity at random MCP-EBPSK modulation signal output of simulation to.

3. multielement positional according to claim 2 is polarity MCP-EBPSK modulation and demodulation method at random, it is characterized in that also comprising digital filter, said step a4) in, the modulation waveform sample is sent into said DAC again after digital filter filtering.

4. multielement positional according to claim 1 is polarity MCP-EBPSK modulation and demodulation method at random; The multielement positional that it is characterized in that realizing this demodulation method is the MCP-EBPSK demodulator of polarity at random; Comprise an analog to digital converter ADC, a digital impact filtering device, envelope detector, a M-1 integration decision device and a multiplexer, the course of work of this demodulator is following:

B1) multielement positional of the ADC simulation that will receive at random the MCP-EBPSK modulation signal of polarity convert into and give numeral after the digital signal and impact filter;

B2) carry out LPF again after the output signal of said envelope detector impact filter takes absolute value;

B3) utilize numeral to impact filter said signal is exported envelope in amplitude and locational difference, adopt the multichannel decision method to realize the demodulation of M binary information symbol;

The impact filtering signal envelope of envelope detector output is divided into M-1 integration decision device of M-1 route to carry out integration respectively and adjudicates; (1≤m≤M-1) the road decision device only is responsible for distinguishing symbol " m " to m; Promptly only adjudicating according to " thresholding m " after to the sample of signal integration, to distinguish symbol " m " and symbol " 0 " the position that code-element period internal symbol " m " possibly occur near;

B4) utilize multiplexer that M-1 road court verdict is merged output, promptly obtain the demodulation result of final M binary information sequence.

5. multielement positional according to claim 4 is polarity MCP-EBPSK modulation and demodulation method at random; It is characterized in that it is a kind of IIR type digital band-pass filter that said numeral is impacted filter; Constitute with at least one pair of conjugate pole zero point by a pair of conjugation; The carrier frequency of the modulation signal that receives is higher than the zero frequency of impact filtering device but is lower than all pole frequencies, and zero frequency and pole frequency near degree, to reach 10 of signal carrier frequency at least ^-2～10 ^-3Magnitude; The transfer function of said digital iir filter is following:

$H\left(z\right)=\frac{\underset{j=0}{\overset{J}{\mathrm{\&Sigma;}}}{b}_j\&CenterDot;z^{-j}}{1-\underset{i=1}{\overset{I}{\mathrm{\&Sigma;}}}{a}_i\&CenterDot;z^{-i}}=\frac{1+\underset{j=1}{\overset{J}{\mathrm{\&Sigma;}}}{b}_j\&CenterDot;z^{-j}}{1-\underset{i=1}{\overset{I}{\mathrm{\&Sigma;}}}{a}_i\&CenterDot;z^{-i}}---\left(4\right)$

A wherein ₀=b ₀=1, z is the Z-transformation domain variable, b _jBe conjugation zero point, a _iBe conjugate pole; Again because numeral is impacted filter by constituting at a pair of conjugation zero point and at least one pair of conjugate pole, so 2=J≤I in (4) formula.

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