CN102546501B - 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 multi-position random polarity MCP-EBPSK modulation and demodulation method, which is based on a modified random polarity continuous phase expansion binary phase shift keying modulation method, which includes a multi-position random polarity MCP - EBPSK modulator and MCP-EBPSK signal demodulator with multiple position random polarity. The MCP-EBPSK modulator with multiple positions and random polarities uses multiple information symbols to modify the random polarity continuous phase keying of the different phase modulation periods of the sinusoidal carrier, and the MCP-EBPSK demodulator with multiple positions and random polarities An impulse filter is included to emphasize the phase modulation information of the received signal and eliminate its polarity variation, so that the demodulation performance is not affected by the multi-position random polarity modulation. The modulated signal of the invention doubles the transmission code rate and spectrum utilization rate of the random polarity CP-EBPSK communication system, occupies narrower bandwidth, wider code rate adaptability range, better demodulation performance and more flexible use.

Description

Modulation and Demodulation Method of Multiple Position Random Polarity MCP-EBPSK

technical field

The invention relates to information modulation and demodulation in digital communication, in particular to an MCP-EBPSK modulation and demodulation method of multi-position random polarity, which belongs to the technical field of digital information transmission with high spectral efficiency.

Background technique

The rapidly growing demand for broadband wireless services puts forward higher and higher requirements for wireless communication, which directly leads to more and more crowded radio frequencies in the air, especially with the third generation (3G) and fourth generation (4G) broadband mobile With the development of communication networks, the contiguous spectrum of lower frequency bands is almost exhausted. The auction price for the right to use 10MHz spectrum for 20 years in Europe has reached 4 billion euros. In my country, it is difficult to buy the most favorable frequency and bandwidth with money. Therefore, like energy and water resources, spectrum is also an important strategic resource of the country, and compressing wireless transmission spectrum to the maximum has important practical significance and direct economic benefits. In order to transmit information at a high speed within a unit frequency band, it is necessary to increase the spectrum utilization rate as much as possible (assessed in bps/Hz), which has become the core competitive index and key common technology of the new generation information transmission system.

1. CP-EBPSK modulation

In order to tighten the spectrum, we have invented a "Continuous Phase-Extended Binary Phase Shift Keying" (CP-EBPSK: Continue Phase-Extended Binary Phase Shift Keying) modulation (see "Extended Binary Phase Shift Keying Modulation for Spectrum Tightening and demodulation method", invention patent authorization announcement number: CN101582868B), its unified expression is:

s ₀ (t)=sinω _c t, 0≤t<T

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

Among them, s ₀ (t) and s ₁ (t) represent the modulation waveforms of symbols “0” and “1” respectively, ω _c is the angular frequency of the modulated carrier, and 0<Δ<1 is the phase modulation index. It can be seen that the symbol period T=2πN/ _ωc lasts for N≥1 carrier periods, and the modulation period of the "1" symbol lasts for K<N carrier periods, and K and N are both integers to ensure full-period modulation.

It can be seen from formula (1) that the CP-EBPSK modulation waveform has the following characteristics:

1) The phase is continuous, and the time waveform is also continuous;

2) The angular frequency of data “0” is ω _c , the angular frequency of data “1” is ω _c ±Δω _c cosω _c t (the derivative of signal phase ω _c t±Δω _c sinω _c t with respect to time t), the instantaneous frequency The change is ±Δ·ω _c , which is a finite value. When Δ<<1, the spectrum of CP-EBPSK modulated wave can be expected to be tightened;

3) If τ=T is taken, modulation of a single carrier cycle can be realized, so that the highest code rate is numerically equal to the carrier frequency, and the bandwidth reaches the widest. As the modulation duty ratio τ/T=K/N decreases (or the modulation index Δ decreases), at a certain power spectral density (PSD: Power Spectrum Density) level, the CP-EBPSK modulated waveform The bandwidth can always tend to the so-called Ultra Narrow Band (UNB: Ultra Narrow Band).

For example, in formula (1), take Δ=0.01, N=16, K=2, _fc = _ωc /2π=40kHz, and the time waveform of the CP-EBPSK modulation signal is shown as the solid line in Figure 1(a) , comparing it with the time waveform of the standard sinusoidal signal (the dotted line in Figure 1(a)), it can be seen that the signal waveform modulated by CP-EBPSK is very close to the sinusoidal wave. Figure 1(b) is the power spectrum of the CP-EBPSK modulated signal, where the ordinate takes the amplitude of the power spectrum at the carrier frequency as 0 dB. It can be seen from Figure 1(b) that when Δ<<1, the energy of the CP-EBPSK modulated signal is highly concentrated, and the amplitude of the carrier frequency (located at 40kHz) is about 70dB (10 million times) higher than that of other sidebands.

The specific implementation is: when the modulator inputs the symbol "0", the modulator selects the waveform sample output shown in s ₀ (t), otherwise when the input is the symbol "1", the modulator selects s ₁ (t ) shows the waveform sample output, the phase modulation indices Δ of the modulation waveforms corresponding to all symbols "1" are equal and remain unchanged.

2. Random polarity CP-EBPSK modulation

Since the larger the phase modulation index Δ, the better the demodulation performance of the CP-EBPSK modulated signal, so the selection of Δ often cannot be too small because it needs to compromise the spectrum utilization rate and energy utilization rate at the same time. For example, in order to obtain a high code rate, we take f _c =30MHz, N=4 (at this time, the code rate is f _c /N=30/N=7.5Mbps), K=2 and Δ=0.1 for simulation, at this time The power spectrum of the CP-EBPSK modulated signal is shown in Figure 2(a). The abscissa in the figure is the frequency, in MHz, and the ordinate is the relative amplitude, in dB. 10,000 symbols were taken when calculating the power spectrum. It can be seen that the sidebands of the power spectrum of the CP-EBPSK modulated signal fail to meet the stricter requirement of less than -60dB at this time, mainly because the sidebands contain relatively high discrete spectrum (ie, line spectrum) components. Therefore, if the line spectrum in the power spectrum sideband of the CP-EBPSK modulated signal can be removed or reduced, it is expected to further reduce the sideband level of the power spectrum of the CP-EBPSK modulated signal.

Note that during the keying modulation period of each symbol "1" of CP-EBPSK, the phase modulation index Δ in formula (1) either remains unchanged, or alternately changes symbols (ie +Δ or -Δ), this rule The nature is the root cause of the line spectrum component (corresponding to the periodic sine component in the time domain) in the PSD sideband. However, if the sign of the phase modulation index Δ (that is, the modulation polarity) is randomly changed (that is, +Δ or -Δ is randomly selected) when the symbol "1" is transmitted, it is expected to reduce or eliminate the sideband line spectrum, thereby further Tighten the power spectrum of CP-EBPSK modulated signal, reduce interference to adjacent channels, and improve spectrum utilization. Therefore, we proposed a "CP-EBPSK communication system and its communication method modulated by pseudo-random sequence" (invention patent application number: 201110092668.X), by adding a pseudo-random sequence to the original CP-EBPSK modulator The generator uses the pseudo-random number it generates to randomly select the polarity of Δ (that is, the sign is positive or negative), that is, in formula (1), the modulation for data "0" remains unchanged, while for data "1", Then examine the value of the current random number of this pseudo-random sequence, if the value is 0, get +Δ in (1) formula, if this value is 1, then get-Δ in (1) formula; "The randomness of the phase change in the keying modulation period removes most of the line spectrum on the PSD main lobe and side lobe of the CP-EBPSK modulation signal, making the spectrum of the modulated signal more compact (more than 20dB as shown in Figure 2(b)), It can be easily evaluated with a more demanding -60dB power bandwidth, and the demodulation performance is basically not affected.

3. MPPSK modulation

In classic pulse modulation applications such as radar systems and pulse ultra-wideband (IR-UWB) communication systems, different symbol information is usually transmitted by using the position of the pulse relative to the carrier, such as pulse position modulation (PPM: PulsePosition Modulation). We once took advantage of this to invent the "multiple position phase shift keying (MPPSK: M-ary Position Phase Shift Keying) modulation and demodulation method" (invention patent number: ZL200710025202.1), using multiple information symbols to Phase shift keying is performed at different phase jump positions, so that the extended binary phase shift keying (EBPSK: Extended Binary Phase Shift Keying) modulation method (for the ZL200710025203.6 patent we invented before, that is, "unified binary phase shift keying) Orthogonal modulation and demodulation method" is extended to multi-ary modulation and demodulation, and the transmission code rate and spectrum utilization rate are doubled under the condition that the spectrum structure and transmission power are almost unchanged.

4. Demodulation of EBPSK modulated signal

Regarding the demodulation of EBPSK modulated signals, we have disclosed a digital zero group A time-delayed infinite impulse response (IIR) filter to highlight phase jumps in EBPSK modulated signals. The digital zero group delay filter is composed of a pair of conjugate zeros and a pair of conjugate poles, the zero frequency is lower than the pole frequency, and the signal carrier frequency is set between the zero frequency and the pole frequency, that is, between the amplitude frequency curve of the filter and the pole frequency Near the intersection point of the phase-frequency curve, to make use of its transient characteristics to make the output of the modulated signal through the filter produce overshoot at the phase modulation, and the closeness of the zero frequency and the pole frequency is not worse than 10 ^-2 of the carrier frequency Magnitude.

"Shock filter method for enhancing asymmetric binary modulation signal" (application number: 200910029875.3, publication number: CN101599754) by adding at least one or more pairs of conjugates near the original poles of the digital zero group delay filter Pole, get a higher overshoot amplitude and better demodulation performance, so it is called a digital shock filter.

Contents of the invention

For continuing to improve the frequency spectrum structure of random polarity CP-EBPSK modulation signal, the object of the present invention is to provide a kind of revised CP-EBPSK (recorded as MCP-EBPSK, i.e. Modified CP-EBPSK) modulation method, and it is extended to multiple The random polarity MCP-EBPSK modulation and demodulation method of the system is used to double the transmission code rate and spectrum utilization rate of the random polarity CP-EBPSK communication system.

In order to solve the above-mentioned technical problems and realize the above-mentioned technical effects, the present invention is realized through the following technical solutions:

A kind of multiple location random polarity MCP-EBPSK modulation and demodulation method, the step comprises:

1. Optimize the power spectrum shape of the random polarity CP-EBPSK modulation signal and improve the demodulation performance.

It can be seen from Figure 1(b) and Figure 2 that CP-EBPSK modulation and random polarity CP-EBPSK modulation signals produce a second side lobe higher than the main lobe of the power spectrum at the double frequency of the carrier frequency, which affects the signal The further tightening of the bandwidth also disperses the energy of the signal. The main reason is that the modulation rate of the signal phase is too fast. For this reason, at first the present invention introduces a power spectrum shape adjustment coefficient η less than 1 in the expression of the random polarity CP-EBPSK modulation signal (being the random polarity CP-EBPSK modulation signal without correction when η=1 ), so as to obtain the expression of the random polarity MCP-EBPSK modulation mode shown in formula (2):

s ₀ (t)=sinω _c t, 0≤t<NT _c

${\mathrm{<span\; class="notranslate">\; the\; s</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\left\{\begin{array}{cc}\mathrm{<span\; class="notranslate">\; sin</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; \&omega;</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; \&xi;</span>}<span\; class="notranslate">\; \&CenterDot;</span>\mathrm{<span\; class="notranslate">\; \&Delta;</span>}\mathrm{<span\; class="notranslate">\; sin</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&eta;</span>}{\mathrm{<span\; class="notranslate">\; \&omega;</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; )</span><span\; class="notranslate">\; ,</span>& \mathrm{<span\; class="notranslate">\; 0</span>}<span\; class="notranslate">\; \&le;</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; <</span>{\mathrm{<span\; class="notranslate">\; KT</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}\\ \mathrm{<span\; class="notranslate">\; sin</span>}{\mathrm{<span\; class="notranslate">\; \&omega;</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; ,</span>& \mathrm{<span\; class="notranslate">\; 0</span>}<span\; class="notranslate">\; <</span>{\mathrm{<span\; class="notranslate">\; KT</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}<span\; class="notranslate">\; \&le;</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; <</span>{\mathrm{<span\; class="notranslate">\; NT</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}\end{array}\right.<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span>$

Among them, T _c = 2π/ω _c is the carrier cycle, ξ∈{-1,1} determines the polarity of phase random modulation, η∈(0,1) is the power spectrum shape adjustment introduced by MCP-EBPSK modulation coefficient. The meanings of other variables are the same as in formula (1).

The power spectrum of the random polarity MCP-EBPSK modulation signal of η=1, 1/2, 1/3, 1/4 and 1/5 under the same conditions compared from Fig. 3 (a) ~ Fig. 3 (e), We can indeed see a tendency for PSD energy to be concentrated towards the carrier frequency and the main lobe. This is very natural, because when η = 0, (2) degenerates into a standard sine wave. When calculating the power spectrum in Figure 3, 100,000 symbols and ²²⁶ -point Fast Fourier Transform (FFT) were selected to ensure the highest possible accuracy and resolution.

From the demodulation performance comparison of these five kinds of random polarity MCP-EBPSK modulation signals shown in Figure 4, when η<1, because the energy of the random polarity MCP-EBPSK modulation signal is more toward its carrier frequency and The PSD main lobe is concentrated, resulting in better bit error rate performance. Especially with the demodulation performance improvement range when η=1/2 is the largest, for example, when the signal-to-noise ratio SNR=32dB in Fig. 4, the demodulation bit error rate ratio of the random polarity MCP-EBPSK modulation of η=1/2 The random polarity CP-EBPSK modulation of η=1 is reduced by nearly 2 orders of magnitude.

2. Extend the random polarity MCP-EBPSK modulation method from binary to multi-ary.

Referring to the aforementioned idea of MPPSK, the random polarity MCP-EBPSK modulation expression defined by formula (2) is expanded into the multi-position random polarity MCP-EBPSK modulation method shown in formula (3):

${\mathrm{<span\; class="notranslate">\; the\; s</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\left\{\begin{array}{ccc}\mathrm{<span\; class="notranslate">\; sin</span>}{\mathrm{<span\; class="notranslate">\; \&omega;</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; ,</span>& \mathrm{<span\; class="notranslate">\; 0</span>}<span\; class="notranslate">\; \&le;</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; <</span>{\mathrm{<span\; class="notranslate">\; NT</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}<span\; class="notranslate">\; ,</span>& \mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0</span>}\\ \left\{\begin{array}{c}\mathrm{<span\; class="notranslate">\; sin</span>}{\mathrm{<span\; class="notranslate">\; \&omega;</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; ,</span>\\ \mathrm{<span\; class="notranslate">\; sin</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; \&omega;</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; \&xi;</span>}<span\; class="notranslate">\; \&Center\; Dot;</span>\mathrm{<span\; class="notranslate">\; \&Delta;</span>}\mathrm{<span\; class="notranslate">\; sin</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; \&eta;\&omega;</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; )</span><span\; class="notranslate">\; ,</span>\\ \mathrm{<span\; class="notranslate">\; sin</span>}{\mathrm{<span\; class="notranslate">\; \&omega;</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; ,</span>\end{array}\right.& \begin{array}{c}\mathrm{<span\; class="notranslate">\; 0</span>}<span\; class="notranslate">\; \&le;</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; \&le;</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>{\mathrm{<span\; class="notranslate">\; KT</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}<span\; class="notranslate">\; ,</span>\\ <span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>{\mathrm{<span\; class="notranslate">\; KT</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}<span\; class="notranslate">\; <</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; <</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; r</span>}}_{\mathrm{<span\; class="notranslate">\; g</span>}}<span\; class="notranslate">\; )</span>{\mathrm{<span\; class="notranslate">\; KT</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}<span\; class="notranslate">\; ,</span>\\ <span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; r</span>}}_{\mathrm{<span\; class="notranslate">\; g</span>}}<span\; class="notranslate">\; )</span>{\mathrm{<span\; class="notranslate">\; KT</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}<span\; class="notranslate">\; \&le;</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; <</span>{\mathrm{<span\; class="notranslate">\; NT</span>}}_{\mathrm{<span\; class="notranslate">\; c</span>}}<span\; class="notranslate">\; ,</span>\end{array}& \mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; \&le;</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; \&le;</span>\mathrm{<span\; class="notranslate">\; m</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}\end{array}\right.<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 3</span>}<span\; class="notranslate">\; )</span>$

Among them, k=0,1,...,M-1 is an M-ary information symbol, and there are M>2 different values; 0≤r _g <1 is a symbol guard interval control factor. M, K, N, η, Δ, and r _g constitute a set of "modulation parameters" that change signal bandwidth, transmission efficiency, and demodulation performance.

When M=2 and r _g =0, formula (3) degenerates into formula (2).

From the power spectrum comparison of the random polarity CP-EBPSK modulation signal shown in Figure 5 (a) and the quaternary CP-EBPSK modulation signal of random polarity shown in Figure 5 (b), from the η shown in Figure 5 (c) =1/2 of the random polarity MCP-EBPSK modulation signal and the power spectrum of the random polarity quaternary MCP-EBPSK modulation signal of η=1/2 shown in Fig. 5 (d), we can see that the introduction After multi-ary modulation, the shape of power spectrum of random polarity CP-EBPSK modulation signal and random polarity MCP-EBPSK modulation signal is basically unchanged, but the line spectrum component is obviously reduced.

3. Perform multi-channel judgment on the shock filter response of the multi-position random polarity MCP-EBPSK modulated signal to realize demodulation.

The receiver of the multi-position random polarity MCP-EBPSK modulated signal still first adopts a digital shock filter to convert the phase modulation of the input signal into the spurious amplitude modulation of the output signal, and then supplements it with multi-channel adaptive threshold judgment detection to realize the multi-element Demodulation of position random polarity MCP-EBPSK modulated signals. The digital impact filter is a special IIR filter, which exhibits notch-frequency selection characteristics in an extremely narrow passband bandwidth, and converts tiny phase jumps in the modulated signal into amplitude shocks, thereby highlighting the The waveform difference in the amplitude of the output signal is eliminated, which is beneficial to realize the demodulation of the phase modulation signal through the threshold judgment.

From the random polarity CP-EBPSK modulation shown in Figure 6, the quaternary CP-EBPSK modulation and the demodulation bit error rate comparison of the quaternary MCP-EBPSK modulation signal of the random polarity of n=1/2 can be seen, in Under the same bit error rate, the signal-to-noise ratio (SNR) required to demodulate the random polarity quaternary MCP-EBPSK modulated signal of η=1/2 is the lowest. This is the result of removing most of the line spectrum components that wasted the transmitting power and making the power spectrum energy more concentrated. More importantly, compared with the CP-EBPSK modulation of random polarity, since the random polarity quaternary MCP-EBPSK modulation of η=1/2 doubles the transmission bit rate, the signal required to transmit each bit of data The noise ratio (ie EbN0) is reduced by half.

The principle of this method is explained as follows:

Based on the MCP-EBPSK modulation mode of random polarity, the MCP-EBPSK modulation mode of described random polarity is expressed as (2) formula, and (2) formula is extended from binary system to multi-ary system, and its expression is as (3 ) shown in the formula. M, K, N, η, Δ, and r _g constitute a set of "modulation parameters" that change signal bandwidth, transmission efficiency, and demodulation performance.

The MCP-EBPSK modulator with multi-position random polarity includes a pseudo-random sequence generator, which uses the pseudo-random number ξ generated by it to control the sign of Δ, which has only two possible values -1 and +1, namely (2) The phase modulation polarity of non-"0" data in formula or (3). The multi-position random polar MCP-EBPSK modulator uses M-ary information symbols to directly control the position of the phase jump moment of the sinusoidal carrier in each non-"0" symbol period through formula (3). The MCP-EBPSK modulator with multi-position random polarity introduces the power spectrum shape adjustment coefficient η to adjust the shape of the modulated signal power spectrum and improve the demodulation performance.

The multi-position random polarity MCP-EBPSK demodulator includes a digital shock filter, which is used to highlight the phase modulation information of the received signal and eliminate its polarity change, so that the demodulation performance is not affected by the random change of phase modulation polarity. The digital shock filter is an infinite impulse response bandpass filter, which is composed of a pair of conjugate zeros and at least one pair of conjugate poles, the zero frequency is lower than the pole frequency, and the signal carrier frequency is higher than the zero of the shock filter Frequency but lower than all pole frequencies, and the closeness between zero frequency and pole frequency should not be inferior to the order of 10 ^-2 ~ 10 ^-3 of the signal carrier frequency, so as to make use of its transient characteristics to make the modulated signal pass through the filter The output produces overshoot at the phase modulation. The MCP-EBPSK demodulator with multi-position random polarity utilizes the difference in amplitude and position of the output envelope of the multi-ary signal symbols by the digital impact filter, and uses a multi-way decision method to realize the demodulation of the M-ary symbols.

The present invention has the following beneficial effects:

1) Spectrum utilization is greatly improved. Since the phase change of the CP-EBPSK modulation mode is continuous during the keying period, the height of the line spectrum in the signal power spectrum is greatly reduced by using random polarity keying modulation, so the bandwidth occupied by the modulated signal is extremely narrow and has a high spectrum utilization. The rate is closer to the "ultra-narrowband" in the traditional sense. The introduction of the power spectrum shape adjustment coefficient η optimizes the shape of the power spectrum, and the introduction of multi-ary modulation not only enables more information symbols to be transmitted in one symbol period, but also doubles the information transmission rate and reduces the line spectrum. Therefore, the bandwidth of the modulated signal is extremely narrow, and the spectrum utilization rate has been greatly improved.

2) The energy utilization rate is greatly improved. Because the shock filter can prevent the demodulator from being affected by the random reversal of the polarity of the signal phase modulation, and because the power spectrum shape adjustment coefficient η can suppress the side lobe height at the 2-fold frequency of the carrier (for example, when η<1/2) , or make it closer to the carrier frequency (for example, when η=1/2), so that the energy of the modulated signal is more concentrated, so that the demodulation performance of the system is also improved. Due to the same sinusoidal carrier, the modulated signal power obtained by using the random polarity multi-ary system MCP-EBPSK modulation of the present invention is the same as that obtained by using the existing random polarity binary CP-EBPSK modulation as a comparison, but the transmitted The bit rate of the information is doubled, so in the case of no intersymbol interference, the signal-to-noise ratio required to transmit each bit of data, that is, E _b /N ₀ , is also doubled, and the energy utilization rate is greatly improved.

3) Wide range of applications. The air spectrum is a scarce natural resource, and the high-efficiency modulation and demodulation method described in the present invention reduces the occupation of spectrum resources from the bottom layer, and is more suitable for using the idea of cognitive radio (Cognitive Radio, CR) to further realize dynamic spectrum access Combined with static narrowband occupation, it can make good use of public resources from the top layer, especially suitable for various bandwidth-limited channels such as digital voice broadcasting, digital walkie-talkie, power line carrier, plastic optical fiber and other application fields.

The above description is only an overview of the technical solutions of the present invention. In order to understand the technical means of the present invention more clearly and implement them according to the contents of the description, the preferred embodiments of the present invention and accompanying drawings are described in detail below. The specific embodiment of the present invention is given in detail by the following examples and accompanying drawings.

Description of drawings

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

Figure 2 is the signal power spectrum comparison between CP-EBPSK modulation and random polarity CP-EBPSK modulation when Δ=0.1, where Figure 2(a) is the power spectrum of CP-EBPSK modulation signal, and Figure 2(b) is the random polarity The power spectrum of a CP-EBPSK modulated signal. The abscissa in the figure is the frequency, the unit is MHz, the ordinate is the relative amplitude, the unit is dB, and 10,000 symbols are selected when calculating the power spectrum.

Figure 3 is the power spectrum of the MCP-EBPSK modulation signal with random polarity when the carrier frequency is 21.4MHz, the sampling frequency is 214MHz, Δ=0.1, K:N=2:10, the abscissa in the figure is the frequency, and the unit is MHz , the ordinate is the relative magnitude, the unit is dB. Wherein, Fig. 3 (a) is the power spectrum of the random polarity CP-EBPSK modulation signal of n=1; Fig. 3 (b) is the power spectrum of the random polarity MCP-EBPSK modulation signal of n=1/2 Fig. 3 (c) is the power spectrum of the random polarity MCP-EBPSK modulation signal of n=1/3; Fig. 3 (d) is the power spectrum of the random polarity MCP-EBPSK modulation signal of n=1/4; Fig. 3(e) is the power spectrum of a random polarity MCP-EBPSK modulated signal with η=1/5.

Figure 4 is a comparison of the demodulation performance of the five random polarity MCP-EBPSK modulation signals shown in Figure 3 .

Figure 5 is the power spectrum comparison of three random polarity CP-EBPSK modulation signals when the carrier frequency is 21.4MHz, the sampling frequency is 214MHz, Δ=0.1, K:N=2:10, M=4, and the power spectrum is calculated 100,000 symbols and ²²⁶ -point FFT were selected, the abscissa in the figure is the frequency, the unit is MHz, and the ordinate is the relative amplitude, the unit is dB. Wherein, Fig. 5 (a) is Fig. 2 (a) redrawn for convenience of comparison, i.e. the power spectrum of the CP-EBPSK modulation signal; Fig. 5 (b) is the power spectrum of the quaternary CP-EBPSK modulation signal; Fig. 5(c) is Figure 3(a) redrawn for the convenience of comparison, that is, the power spectrum of the unmodified random polarity CP-EBPSK modulation signal with n=1; Figure 5(d) is the quadrature Make the power spectrum of the CP-EBPSK modulation signal; Fig. 5 (e) is Fig. 3 (b) redrawn for convenience of comparison, namely the power spectrum of the random polarity MCP-EBPSK modulation signal of n=1/2; Fig. 5 (f) is the power spectrum of the quaternary MCP-EBPSK modulated signal of random polarity with n=1/2.

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

Fig. 7 is a block diagram of circuit realization of MCP-EBPSK modulator with multi-position random polarity.

Fig. 8 is an example of the time-domain waveform of the random polarity quaternary MCP-EBPSK modulation signal with η=1/2, and the modulation parameters are Δ=0.1, K:N=2:10, M=4. The abscissa indicates the number of sampling points, and the ordinate indicates the signal amplitude.

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

Fig. 10 is a circuit realization block diagram of multi-position random polarity MCP-EBPSK demodulator based on digital impact filter multiple decision.

Fig. 11 is the bit error rate curve of demodulation η=1/2 random polarity quaternary MCP-EBPSK modulated signal obtained by simulation based on the digital shock filter coefficient provided by the present invention, and no channel coding is used.

Detailed ways

The present invention will be described in detail below with reference to the accompanying drawings and in combination with embodiments.

1. MCP-EBPSK modulator with multiple positions and random polarity

Fig. 7 is the implementation block diagram of the multi-ary MCP-EBPSK signal modulator of described random polarity, and described modulator comprises a pseudo-random sequence generator, a waveform sample storage module, a clock generator, a digital-to-analog converter (DAC), and an optional digital filter. Its working process is as follows:

1) The pseudo-random sequence generator uses the pseudo-random number ξ∈{-1,1} that it generates with only two possible values -1 and +1 to control the sign of the phase modulation index Δ, namely (2) The phase modulation polarity of non-"0" data in formula or (3).

2) The waveform sample storage module has the functions of read-only memory (ROM) and multiplexer (MUX) simultaneously, and has stored the waveform sample of the modulation signal S _k (t) shown in (3) formula, as shown in Figure 8 shown (note that the waveforms differ very little). Under the beat control of the clock pulse generated by the clock generator, the corresponding modulation waveform samples are jointly selected from the input multi-ary information symbol sequence and the output of the pseudo-random sequence generator.

3) When sending the "0" symbol in the multi-ary information sequence, directly select the modulated waveform sample S ₀ (t) to output, without considering the output value of the pseudo-random sequence generator; and when sending a non-"0" symbol, the modulation waveform corresponding to the phase modulation index +Δ and -Δ must be selected according to the value of the pseudo-random number ξ∈{-1,1} generated by the pseudo-random sequence generator, that is, the operation is directly completed "ξ·Δ".

4) The selected corresponding modulated waveform samples are filtered by the digital filter and then sent to the DAC, that is, converted into an analog random polarity multi-ary MCP-EBPSK modulated signal for output.

5) Since the sidelobe of the power spectrum of the multivariate position random polarity MCP-EBPSK modulation signal of the present invention has been greatly suppressed (for example, it has been lower than -70dB in Fig. 9), so the digital filtering link in Fig. 7 is generally no longer needed .

In order to give an intuitive spectrum utilization index, according to the strict -60dB bandwidth standard of the US Federal Communications Commission (FCC), the random polarity CP-EBPSK modulation, the multi-ary CP-EBPSK modulation and the multi-element η=1/2 The position random polarity CP-EBPSK modulation has carried out the -60dB bandwidth and spectrum utilization rate statistics, the result is shown in Table 1 and Table 2. The signal carrier frequency in the table is 21.4MHz. 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 can be seen that in all cases, the spectrum utilization rate exceeds 230bps/Hz, which is much higher than the current modulation method

Table 1 Comparison of -60dB bandwidth and spectrum utilization of three modulation methods when K=2

Table 2 Comparison of -60dB bandwidth and spectrum utilization of three modulation methods when N=30

2. MCP-EBPSK demodulator with multiple positions and random polarity

Fig. 10 is the realization block diagram of the MCP-EBPSK demodulator of described multivariate position random polarity, and described demodulator comprises an analog-to-digital converter (ADC), a digital shock filter, an envelope detector, M- 1 integral decision device, and a multiplexer. Its working process is as follows:

1) The ADC converts the received analog MCP-EBPSK modulated signal (generally down-converted to an intermediate frequency signal) into a digital signal and sends it to the digital impact filter.

2) The digital impact filter is a special type IIR digital bandpass filter, which is composed of a pair of conjugate zeros and at least a pair of conjugate poles, and the carrier frequency of the MCP-EBPSK modulation signal with multiple position random polarity It is higher than the zero frequency of the impact filter but lower than all the pole frequencies, and the closeness between the zero frequency and the pole frequency must be at least on the order of 10 ^-2 to 10 ^-3 of the signal carrier frequency. Usually the transfer function of a digital IIR filter can be written as follows:

$\mathrm{<span\; class="notranslate">\; h</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; z</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\frac{\underset{\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0</span>}}{\overset{\mathrm{<span\; class="notranslate">\; J</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{\mathrm{<span\; class="notranslate">\; b</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; z</span>}}^{<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; j</span>}}}{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span>\underset{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; I</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{\mathrm{<span\; class="notranslate">\; a</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; z</span>}}^{<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; i</span>}}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>\underset{\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; J</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{\mathrm{<span\; class="notranslate">\; b</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; z</span>}}^{<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; j</span>}}}{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span>\underset{\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; I</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{\mathrm{<span\; class="notranslate">\; a</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; z</span>}}^{<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; i</span>}}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 4</span>}<span\; class="notranslate">\; )</span>$

Where a ₀ =b ₀ =1, z is a variable in the Z transform domain, b _j is a conjugate zero point, and a _i is a conjugate pole. And because the digital impact filter is composed of a pair of conjugate zeros and at least one pair of conjugate poles, so 2=J≤I in the formula (4).

For the multivariate position random polarity MCP-EBPSK modulation signal of η=1/2, the present embodiment utilizes automatic search to obtain the following shock filter design results:

1 pair of conjugate zeros and 1 pair of conjugate poles:

b ₁ =-1.618640351773825, b ₂ =1;

a ₁ =-1.449036912558672, a ₂ =0.802018791906955.

1 pair of conjugate zeros and 2 pairs of conjugate poles:

b ₁ =-1.618995687176257, b ₂ =1;

a ₁ =-1.817361012430280, a ₂ =1.436763412570941, a ₃ =-0.513559435879943,

a ₄ =0.079854429688135.

1 pair of conjugate zeros and 3 pairs of conjugate poles:

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.

1 pair of conjugate zeros and 4 pairs of conjugate poles:

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.

1 pair of conjugate zeros and 5 pairs of conjugate poles:

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) The envelope detector performs low-pass filtering after taking the absolute value of the output signal of the shock filter, so as to cooperate with the shock filter to highlight the phase modulation information of the received signal and eliminate its polarity change, so that the demodulation Performance is not affected by pseudo-random sequence phase modulation.

4) Utilizing the difference in amplitude and position of the signal output envelope by the digital impact filter, and adopting a multi-path judgment method to realize the demodulation of the M-ary information symbol. As shown in Figure 10, the impact filter signal envelope output by the envelope detector is divided into M-1 paths for integral judgment respectively, and the mth (1≤m≤M-1) path decision device is only responsible for distinguishing the symbols "m", that is, the signal samples are only integrated near the position where the symbol "m" may appear in the symbol period and then judged according to the "threshold m" to distinguish the symbol "m" from the symbol "0" (of course, the bit synchronization pulse under the control of , and the common knowledge in the field of bit synchronization pulse extraction is omitted in FIG. 10 ). That is to say, the MCP-EBPSK demodulator of multivariate position random polarity of the present invention utilizes the magnitude of shock filter output signal envelope to distinguish symbol "m" and symbol "0"; The position (relative to the time delay of the symbol "1") to distinguish each non-"0" information symbol. In order to locate the symbol "1", we can simply make the duration K corresponding to the symbol " ₁ " slightly larger than the duration K corresponding to the other M-2 non-"0" information symbols. For example, when K=2, take K1 as 3 or 4, so that after shock filtering and envelope detection, the shock amplitude corresponding to the symbol "1" will obviously exceed the amplitude of other M-1 symbols (including the symbol "0") .

5) Utilize the multiplexer to combine and output the M-1 path decision results to obtain the final demodulation result of the M-ary information sequence (if the input signals of the M-1 path decision device do not exceed the response threshold value, the final demodulation result is judged to be the symbol "0"). Because when there is no inter-symbol interference, the decision output results of each path do not overlap each other in time, so the output of the multiplexer is the superposition of the output results of the M-1 path decision devices.

Based on the digital shock filter coefficients designed above, the quaternary random polarity MCP-EBPSK modem is simulated, and the bit error rate curve shown in Figure 11 is obtained, which shows that 1 pair of conjugated zeros and 3 pairs of conjugated The demodulation performance of the pole digital filter is the best (the situation of more than 3 pairs of conjugate poles is not drawn), and the calculation amount is moderate.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and changes. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims (3)

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

1) optimize the expansion of random polarity continuous phase binary phase shift keying (CP-EBPSK:Continue Phase-Extended Binary Phase Shift Keying) modulation signal power spectrum shape and promote demodulation performance;

The uniform expression of CP-EBPSK modulation is:

S ₀(t)＝sinω _ct， 0≤t<T

$S_1\left(t\right)=\left\{\begin{array}{c}\sin ({\mathrm{\&omega;}}_{c}t\&PlusMinus;\mathrm{\&Delta;}\sin {\mathrm{\&omega;}}_{c}t),0\&le;t<\mathrm{\&tau;},0<\mathrm{\&Delta;}<1\\ \sin {\mathrm{\&omega;}}_{c}t,0<\mathrm{\&tau;}\&le;t<T\end{array}\right.---\left(1\right)$

Wherein, S ₀and S (t) ₁(t) represent respectively the modulation waveform of code element " 0 " and " 1 ", ω _cfor the angular frequency of modulated carrier, 0< Δ <1 is phase-modulation index; Visible 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 ensure modulation complete cycle;

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

S ₀(t)＝sinω _ct， 0≤t<NT _c

$S_1\left(t\right)=\left\{\begin{array}{c}\sin ({\mathrm{\&omega;}}_{c}t+\mathrm{\&xi;}\&CenterDot;\mathrm{\&Delta;}\sin \left(\mathrm{\&eta;}{\mathrm{\&omega;}}_{c}t\right)),0\&le;t<{\mathrm{KT}}_c\\ \sin {\mathrm{\&omega;}}_{c}t,0<{\mathrm{KT}}_c\&le;t<{\mathrm{NT}}_c\end{array}\right.---\left(2\right)$

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

2) random polarity multielement positional phase shift keying (MPPSK:M-ary Position Phase Shift Keying) modulation system is extended to multi-system by binary system:

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

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

Wherein, k=0,1 ..., M-1 is M binary information symbol, has the value that M>2 kind is different; 0≤r _g<1 is the symbol protection Separation control factor; By M, K, N, η, Δ and r _gform 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) the impact filtering response of the random polarity MCP-EBPSK modulation signal of multielement positional is carried out to multichannel judgement and realizes demodulation:

To the MCP-EBPSK modulation signal of the random polarity of multielement positional receiving, first adopt digital shock filter the phase-modulation that receives signal to be converted into the parasitic amplitude modulation of output signal; Be aided with again the judgement of multichannel adaptive threshold and detect the demodulation that realizes the random polarity MCP-EBPSK modulation signal of described multielement positional;

Realize the multi-system MCP-EBPSK signal modulator of the random polarity 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 as follows:

What a1) pseudo-random sequence generator utilized that it produces only have-1 and+1 two kind may value pseudo random number ξ ∈ { 1,1} controls the symbol of phase-modulation index Δ, i.e. the phase-modulation polarity of non-" 0 " data in (2) formula or (3) formula;

A2) 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 rhythm control of the clock pulse producing at clock generator, go out corresponding modulation waveform sample by the output common choice of the multi-system information symbol sequence of inputting and described pseudo-random sequence generator;

A3) when send in multi-system information sequence " 0 " code element time, directly select modulation waveform sample S ₀(t) output; And when sending when non-" 0 " code element, the pseudo random number ξ ∈ that must produce according to pseudo-random sequence generator the value of 1,1}, select phase-modulation index+Δ and-the corresponding modulation waveform of Δ, directly completed computing " ξ Δ ";

A4) selected go out corresponding modulation waveform sample send into described DAC, converted the random polarity multi-system MCP-EBPSK modulation signal output of simulation to;

Described digital shock filter is a kind of IIR type digital band-pass filter, by forming at a pair of conjugation zero point and at least one pair of conjugate pole, the carrier frequency of the modulation signal receiving is higher than the zero frequency of shock filter but lower than all pole frequencies, and the close degree of zero frequency and pole frequency at least will reach 10 of signal carrier frequency ^-2～10 ^-3magnitude; The transfer function of described IIR digital filter based is as follows:

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

Wherein a ₀=b ₀=1, z is Z-transformation domain variable, b _jfor conjugation zero point, a _ifor conjugate pole; Again because digital shock filter is by forming at a pair of conjugation zero point and at least one pair of conjugate pole, therefore 2=J≤I in (4) formula.

2. the random polarity MCP-EBPSK modulation and demodulation of multielement positional according to claim 1 method, is characterized in that also comprising digital filter, described step a4) in, modulation waveform sample is sent into described DAC after digital filter filtering again.

3. the random polarity MCP-EBPSK modulation and demodulation of a multielement positional method, is characterized in that step comprises:

1) optimize the expansion of random polarity continuous phase binary phase shift keying (CP-EBPSK:Continue Phase-Extended Binary Phase Shift Keying) modulation signal power spectrum shape and promote demodulation performance;

The uniform expression of CP-EBPSK modulation is:

S ₀(t)＝sinω _ct， 0≤t<T

$S_1\left(t\right)=\left\{\begin{array}{c}\sin ({\mathrm{\&omega;}}_{c}t\&PlusMinus;\mathrm{\&Delta;}\sin {\mathrm{\&omega;}}_{c}t),0\&le;t<\mathrm{\&tau;},0<\mathrm{\&Delta;}<1\\ \sin {\mathrm{\&omega;}}_{c}t,0<\mathrm{\&tau;}\&le;t<T\end{array}\right.---\left(1\right)$

Wherein, S ₀and S (t) ₁(t) represent respectively the modulation waveform of code element " 0 " and " 1 ", ω _cfor the angular frequency of modulated carrier, 0< Δ <1 is phase-modulation index; Visible 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 ensure modulation complete cycle;

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

S ₀(t)＝sinω _ct， 0≤t<NT _c

$S_1\left(t\right)=\left\{\begin{array}{c}\sin ({\mathrm{\&omega;}}_{c}t+\mathrm{\&xi;}\&CenterDot;\mathrm{\&Delta;}\sin \left(\mathrm{\&eta;}{\mathrm{\&omega;}}_{c}t\right)),0\&le;t<{\mathrm{KT}}_c\\ \sin {\mathrm{\&omega;}}_{c}t,0<{\mathrm{KT}}_c\&le;t<{\mathrm{NT}}_c\end{array}\right.---\left(2\right)$

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

2) random polarity multielement positional phase shift keying (MPPSK:M-ary Position Phase Shift Keying) modulation system is extended to multi-system by binary system:

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

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

Wherein, k=0,1 ..., M-1 is M binary information symbol, has the value that M>2 kind is different; 0≤r _g<1 is the symbol protection Separation control factor; By M, K, N, η, Δ and r _gform 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) the impact filtering response of the random polarity MCP-EBPSK modulation signal of multielement positional is carried out to multichannel judgement and realizes demodulation:

To the MCP-EBPSK modulation signal of the random polarity of multielement positional receiving, first adopt digital shock filter the phase-modulation that receives signal to be converted into the parasitic amplitude modulation of output signal; Be aided with again the judgement of multichannel adaptive threshold and detect the demodulation that realizes the random polarity MCP-EBPSK modulation signal of described multielement positional;

4) realize the MCP-EBPSK demodulator of the random polarity of multielement positional of this demodulation method, comprise an analog to digital converter ADC, a digital shock filter, envelope detector, a M-1 integration decision device and a multiplexer, the course of work of this demodulator is as follows:

B1) ADC gives digital shock filter after the MCP-EBPSK modulation signal of the random polarity of multielement positional of the simulation receiving is converted to digital signal;

B2) output signal of described envelope detector impact filter is carried out low-pass filtering again after taking absolute value;

B3) utilize digital shock filter to export envelope in amplitude and locational difference to described signal, adopt 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 and carries out respectively integration judgement, m (1≤m≤M-1) road decision device is only responsible for distinguishing symbol " m ", near the position that only may occur at code-element period internal symbol " m ", adjudicate according to " thresholding m " after to sample of signal integration, to distinguish symbol " m " and symbol " 0 ";

B4) utilize multiplexer JiangM-1 road court verdict to merge output, obtain the demodulation result of final M binary information sequence;

Described digital shock filter is a kind of IIR type digital band-pass filter, by forming at a pair of conjugation zero point and at least one pair of conjugate pole, the carrier frequency of the modulation signal receiving is higher than the zero frequency of shock filter but lower than all pole frequencies, and the close degree of zero frequency and pole frequency at least will reach 10 of signal carrier frequency ^-2～10 ^-3magnitude; The transfer function of described IIR digital filter based is as follows:

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

Wherein a ₀=b ₀=1, z is Z-transformation domain variable, b _jfor conjugation zero point, a _ifor conjugate pole; Again because digital shock filter is by forming at a pair of conjugation zero point and at least one pair of conjugate pole, therefore 2=J≤I in (4) formula.