CN101252568B - Frequency domain direct sequence spread-spectrum and fractional number Fourier field csep signal spread-spectrum transmitting method - Google Patents

Abstract

Disclosed is a frequency domain direct sequence spread spectrum and fractional Fourier domain chip signal spread spectrum transmission method, relating to the mixed spread spectrum technology and solving the problems that interference signals in a receiver have influence on a single spread spectrum system and single-frequency sinusoidal interference causes the best energy accumulation having moreinterference on the direct sequence spread spectrum system after the traditional Fourier transformation. In an emission process, a binary information code source is branched into two paths of binary information by a serial-to-parallel converter and the two paths of binary information are respectively modulated and then summarized to produce an emission signal s(t). In a receiving process, the received signal is ensured to respectively go through a radio frequency filter, a sampler and a p-order fractional Fourier transformer to produce a fractional domain signal rp(u). In one demodulation process, the rp(u) is ensured to respectively go through a multi-order fractional Fourier domain filter and a multi-order fractional Fourier domain transformer, a direct spread spectrum sequence generator, a carrier signal generator and a filter to produce a user demodulation information r1(t); and in the other demodulation process, rp(u) is ensured to go through a peak position decider to produce a r2(t); the r1(t) and the r2(t) are ensured to go through the serial-to-parallel transformer to produce a demodulation information r(t).

Description

Frequency domain direct sequence spread spectrum and fractional number Fourier field are cut general signal spread-spectrum transmitting method

Technical field

The present invention relates to the mixing spread spectrum technique in a kind of radio communication, be specifically related to a kind of frequency domain direct sequence spread spectrum and score field and cut the method that general signal spread-spectrum combined spread spectrum signal produces and receives.

Background technology

The frequency spectrum that spread spectrum communication system is meant information signal to be transmitted becomes broadband signal after with the irrelevant spread spectrum function expansion of certain specific and information signal to be transmitted, send in the channel and transmit, utilize corresponding techniques or means with its frequency spectrum compression of having expanded at receiving terminal, revert to the bandwidth of original information signal to be transmitted, thereby reach the communication system of transmission information purpose.Produce the mode of spread-spectrum signal according to communication system, can be divided into Resistant DS Spread Spectrum System, frequency-hopping spread-spectrum system, several classes such as THSS system, the characteristics of spread spectrum communication system maximum are to have very strong antijamming capability, the interference that enters receiver mainly contains band limit stable Gaussian random disturbances, arrowband spot jamming and broadband barrage jamming etc., when interference signal aims at the centre frequency of spread spectrum system, radio-frequency carrier for Resistant DS Spread Spectrum System has extremely strong interference, and the interference when the broadband is blocked, bigger for frequency-hopping spread-spectrum system harm, the hybrid spread spectrum communication mode is than single direct sequence, frequency hopping, the THSS mode has more excellent characteristic.

Fractional Fourier transform is a kind of generalized form of Fourier transform, can be interpreted as signal the time plane internal coordinate axle be rotated counterclockwise method for expressing on the fractional order Fourier domain that arbitrarily angled back constitutes around initial point, because fractional Fourier transform has the character that many traditional Fourier transforms do not possess, have in the signal processing field in recent years comparatively widely and use.The integrated form of fractional Fourier transform is defined as:

$F^{p}f\left(u\right)={\∫}_{-\∞}^{+\∞}f\left(t\right){\mathrm{\κ}}_p(u,t)\mathrm{dt}$

$=\left\{\begin{array}{cc}\sqrt{\frac{1-i\cot \mathrm{\&alpha;}}{2\mathrm{\&pi;}}}{\&Integral;}_{-\&infin;}^{+\&infin;}\exp \left[i(\frac{u^2+{\mathrm{<figure-callout\; id="2"\; label="t"\; filenames="DEST\_PATH\_RE-HSB00000014059100011.png,S2008100643123E00011.png"\; state="\{\{state\}\}">t</figure-callout>}}^2}{2}\cot \mathrm{\&alpha;}-\mathrm{ut}\csc \mathrm{\&alpha;})\right]f\left(t\right)\mathrm{dt}& \mathrm{\&alpha;}\&NotEqual;\mathrm{n\&pi;}\\ f\left(t\right)& \mathrm{\&alpha;}=2\mathrm{n\&pi;}\\ f(-t)& \mathrm{\&alpha;}=(2n\&PlusMinus;1)\mathrm{\&pi;}\end{array}\right.$

Wherein f (t) is the time domain expression-form of signal, F ^pF (u) is the p rank fractional Fourier transform of f (t), K _p(u t) is transformation kernel, and u is the score field coordinate, α=p pi/2.The inverse transformation of fractional Fourier transform can be expressed as:

$F^{p}f\left(u\right)={\&Integral;}_{-\&infin;}^{+\&infin;}f\left(t\right){\mathrm{\&kappa;}}_{-p}(u,t)\mathrm{dt}$

Therefore the fraction Fourier conversion of signal f (t) can be interpreted as f (t) and examine κ with inverse transformation _-p(u, t) be the base function space on expansion, this fraction Fourier conversion nuclear is one group of quadrature, the frequency modulation rate is Qie Pu (Qie Pu) base of cot α (α=p pi/2), therefore cut general signal will show as an impulse function in suitable fraction Fourier conversion territory for one, promptly fractional Fourier transform has best energy accumulating characteristic to the given general signal of cutting in certain fractional order Fourier domain.The expression formula of wherein cutting general signal is:

Parameter

f ₀, k controls phase place, centre frequency and the frequency modulation rate of cutting general signal respectively, A represents to cut the amplitude of general signal, the pass of k and bandwidth B is B=kT, wherein T is for cutting general signal time domain width.Cutting general signal in expression formula is complex signal, and transmitting terminal should send real signal in real system is used, and therefore gets two conjugation and cuts general signal stack, and phase place gets 0, makes it become the cosine function form:

c(t)＝{exp[i(2πf ₀t+πkt ²)]+exp[-i(2πf ₀t+πkt ²)]}/2

＝cos(2πf ₀t+πkt ²)

The basic function of tradition Fourier transform is sinusoidal wave, therefore single frequency sinusoidal is disturbed best energy accumulating behind traditional Fourier transform, so disturb bigger for Resistant DS Spread Spectrum System, and when fractional Fourier transform under the situation of p ≠ 1, single frequency sinusoidal is disturbed does not have tangible energy accumulating effect.

Summary of the invention

The objective of the invention is in order to solve the problem that interference signal in the receiver disturbs the optimum energy capture that produces that Resistant DS Spread Spectrum System is disturbed to the influence of single spread spectrum system and single frequency sinusoidal behind traditional Fourier transform.

Technical scheme of the present invention realizes by following steps:

Emission process:

Step 1: binary message sign indicating number source obtains two-way binary message c by first deserializer ₁(t), c ₂(t).

Step 2: the first direct spreading sequence generator generates direct spread spectrum sequence signals b ₁(t), binary message c ₁(t) direct spread spectrum sequence signals b therewith ₁(t) multiply each other, obtain Direct Sequence Spread Spectrum Signal m ₁(t), the signal n of first carrier signal generator output ₁(t) with Direct Sequence Spread Spectrum Signal m ₁(t) multiply each other and carry out binary phase shift keying modulation, obtain modulation signal s ₁(t).

Step 3: cut general signal generator output and cut general signal f (t), binary message c ₂(t) with the modulation of cutting general signal f (t) process waveform maker, obtain modulation signal s ₂(t).Work as c ₂(t) be at 1 o'clock, waveform maker output frequency modulation rate is the general signal of cutting of k; Work as c ₂(t) be at 0 o'clock, waveform maker output frequency modulation rate is the general signal of cutting of-k.At last with modulation signal s ₁(t) with modulation signal s ₂(t) launch through the user side antenna by the transmission signal s (t) that obtains after the adder addition.

Receiving course:

Step 4: the signal R (t) that receives is obtained score field signal r by p rank fractional Fourier transform device after through radio-frequency filter and sampler _p(u), then with score field signal r _p(u) carry out demodulation respectively.

Step 5: first via demodulating process, score field signal r _p(u) earlier by the fractional number Fourier field filter filtering of p rank cut (the 2 π f of exp[i in the general signal ₀T+ π kt ²)]/2 energy, convert the signal into the 2-p rank by 2-2p rank fractional Fourier transform device again, afterwards by the fractional number Fourier field filter filtering of 2-p rank cut (the 2 π f of exp[-i in the general signal ₀T-π kt ²)]/2 energy, obtain time-domain signal r by p-2 rank fractional Fourier transform device again _s(t), the direct spread spectrum sequence signals b of the second direct spreading sequence generator generation and reception and signal Synchronization ₂(t), this direct spread spectrum sequence signals b ₂(t) with time-domain signal r _s(t) multiply each other and carry out despreading, the signal n of signal after the despreading and the output of the second carrier signal maker ₂(t) multiply each other and obtain restituted signal, this restituted signal obtains user's demodulating information r by filter ₁(t);

The second road demodulating process will be by the score field signal r that obtains behind the fractional Fourier transform device of p rank _p(u) adjudicate by the peak decision device, half section time output 1 exports 0 when peak appears at score field during the second half section before peak appears at score field, obtains user's demodulating information r ₂(t).

Step 6: two-way user demodulating information r ₁(t) and r ₂(t) obtain demodulating information r (t) by second deserializer; Above-mentioned formula f ₀The expression centre frequency, k represents the frequency modulation rate, and the pass of k and bandwidth B is B=kT, and wherein T is for cutting general signal time domain width.

The present invention utilized traditional Resistant DS Spread Spectrum System with based on the method for cutting general signal spread-spectrum of fractional Fourier transform, proposed the frequency domain direct sequence spread spectrum and cut the general signal spread-spectrum method of mixing spread-spectrum linked together with fractional number Fourier field, make and exist in the transmission course and the same situation of the single frequency sinusoidal wave interference (a kind of interference the most serious) of homophase frequently of frequency domain Resistant DS Spread Spectrum System carrier wave the frequency domain Resistant DS Spread Spectrum System, because sine wave can be as produce obvious energy accumulating in traditional Fourier domain in score field, therefore to the interference reduction of demodulation, increase with respect to traditional Resistant DS Spread Spectrum System antijamming capability, because the process of two-way band spectrum modulation and demodulation is all in identical frequency band, realize multiplexing of channel, therefore also strengthened the disguise and the fail safe of system.

Description of drawings

Fig. 1 is the structural representation of emitter of the present invention; Fig. 2 is the structural representation of receiving system of the present invention; Fig. 3 is that frequency modulation rate k is the oscillogram of the general signal p of 1 o'clock cut rank fractional number Fourier field; Fig. 4 is that frequency modulation rate k is-1 o'clock the oscillogram of cutting general signal p rank fractional number Fourier field; Fig. 5 is binary message c ₂(t) be the oscillogram of 1 o'clock received signal r (t) by the signal score field behind radio-frequency filter 6, sampler 7 and the p rank fractional Fourier transform device 8; Fig. 6 is binary message c ₂(t) be the oscillogram of 0 o'clock received signal R (t) by the signal score field behind radio-frequency filter 6, sampler 7 and the p rank fractional Fourier transform device 8.

Embodiment

Embodiment one: present embodiment is described in conjunction with Fig. 1 and Fig. 2.

The emitter of present embodiment Fig. 1 by first deserializer 1, the first direct spreading sequence generator 2, first carrier signal generator 3, waveform maker 4, cut general signal generator 5 and form.

Step 1: binary message sign indicating number source 15 obtains two-way binary message c by first deserializer 1 ₁(t), c ₂(t);

Step 2: the first direct spreading sequence generator 2 generates direct spread spectrum sequence signals b ₁(t), binary message c ₁(t) direct spread spectrum sequence signals b therewith ₁(t) multiply each other, obtain Direct-Spread signal m ₁(t), the signal n of first carrier signal generator 3 outputs ₁(t) with Direct-Spread signal m ₁(t) multiply each other and carry out binary phase shift keying modulation, obtain modulation signal s ₁(t);

Step 3: cut general signal generator 5 outputs and cut general signal f (t), binary message c ₂(t) with the modulation of cutting general signal f (t) process waveform maker 4, obtain modulation signal s ₂(t), work as c ₂(t) be at 1 o'clock, waveform maker 4 output frequency modulation rates are the general signal of cutting of k, work as c ₂(t) be at 0 o'clock, waveform maker 4 output frequency modulation rates are for the general signal of cutting of-k, at last with modulation signal s ₁(t) with modulation signal s ₂(t) launch through the user side antenna by the transmission signal s (t) that obtains after the adder addition.

The receiving system of present embodiment Fig. 2 is made up of radio-frequency filter 6, sampler 7, p rank fractional Fourier transform device 8, p rank fractional number Fourier field filter 9,2-2p rank fractional Fourier transform device 10,2-p rank fractional number Fourier field filter 11, p-2 rank fractional Fourier transform device 12, the second direct spreading sequence generator 22, the second carrier signal maker 33, filter 13, peak decision device 14 and second deserializer 21.

Step 4: signal R (t) r (t) that receives is obtained score field signal r through radio-frequency filter 6 and sampler 7 backs by p rank fractional Fourier transform device 8 _p(u), then with score field signal r _p(u) carry out demodulation respectively;

Step 5: first via demodulating process, score field signal r _p(u) earlier by fractional number Fourier field filter 9 filterings of p rank cut (the 2 π f of exp[i in the general signal ₀T+ π kt ²)]/2 energy, again by converting the signal into the 2-p rank behind the 2-2p rank fractional Fourier transform device 10, afterwards by fractional number Fourier field filter 11 filterings of 2-p rank cut (the 2 π f of exp[-i in the general signal ₀T-π kt ²)]/2 energy, obtain time-domain signal r by p-2 rank fractional Fourier transform device 12 again _s(t), the direct spread spectrum sequence signals b of 22 generations of the second direct spreading sequence generator and reception and signal Synchronization ₂(t), this direct spread spectrum sequence signals b ₂(t) with time-domain signal r _s(t) multiply each other and carry out despreading, the signal n of signal after the despreading and 33 outputs of the second carrier signal maker ₂(t) multiply each other and obtain restituted signal, this restituted signal obtains user's demodulating information r by filter 13 ₁(t);

The second road demodulating process will be by the score field signal r that obtains behind the p rank fractional Fourier transform device 8 _p(u) adjudicate by peak decision device 14, half section time output 1 exports 0 when peak appears at score field during the second half section before peak appears at score field, obtains user's demodulating information r ₂(t);

Step 6: two-way user demodulating information r ₁(t) and r ₂(t) obtain demodulating information r (t) by second deserializer 21.

Claims (1)

1. frequency domain direct sequence spread spectrum and fractional number Fourier field are cut general signal spread-spectrum transmitting method, it is characterized in that it is realized by following steps:

Emission process:

Step 1: binary message sign indicating number source (15) obtains two-way binary message c by first deserializer (1) ₁(t), c ₂(t);

Step 2: the first direct spreading sequence generator (2) generates direct spread spectrum sequence signals b ₁(t), binary message c ₁(t) direct spread spectrum sequence signals b therewith ₁(t) multiply each other, obtain Direct-Spread signal m ₁(t), the signal n of first carrier signal generator (3) output ₁(t) with Direct-Spread signal m ₁(t) multiply each other and carry out binary phase shift keying modulation, obtain modulation signal s ₁(t);

Step 3: cut general signal generator (5) output and cut general signal f (t), binary message c ₂(t) with the modulation of cutting general signal f (t) process waveform maker (4), obtain modulation signal s ₂(t), work as c ₂(t) be at 1 o'clock, waveform maker (4) output frequency modulation rate is the general signal of cutting of k, works as c ₂(t) be at 0 o'clock, waveform maker (4) output frequency modulation rate is for the general signal of cutting of-k, at last with modulation signal s ₁(t) with modulation signal s ₂(t) launch through the user side antenna by the transmission signal s (t) that obtains after the adder addition;

Receiving course:

Step 4: the signal R (t) that receives is obtained score field signal r through radio-frequency filter (6) and sampler (7) back by p rank fractional Fourier transform devices (8) _p(u), then with score field signal r _p(u) carry out demodulation respectively;

Step 5: first via demodulating process, score field signal r _p(u) earlier by p rank fractional number Fourier field filters (9) filtering cut (the 2 π f of exp[i in the general signal ₀T+ π kt ²)]/2 energy, again by converting the signal into the 2-p rank behind the 2-2p rank fractional Fourier transform devices (10), afterwards by 2-p rank fractional number Fourier field filters (11) filtering cut (the 2 π f of exp[-i in the general signal ₀T-π kt ²)]/2 energy, obtain time-domain signal r by p-2 rank fractional Fourier transform devices (12) again _s(t), the direct spread spectrum sequence signals b of second direct spreading sequence generator (22) generation and reception and signal Synchronization ₂(t), this direct spread spectrum sequence signals b ₂(t) with time-domain signal r _s(t) multiply each other and carry out despreading, the signal n of signal after the despreading and the output of the second carrier signal maker (33) ₂(t) multiply each other and obtain restituted signal, this restituted signal obtains user's demodulating information r by filter (13) ₁(t);

The second road demodulating process will be by the score field signal r that obtains behind the p rank fractional Fourier transform devices (8) _p(u) adjudicate by peak decision device (14), half section time output 1 exports 0 when peak appears at score field during the second half section before peak appears at score field, obtains user's demodulating information r ₂(t);

Step 6: two-way user demodulating information r ₁(t) and r ₂(t) obtain demodulating information r (t) by second deserializer (21);

Above-mentioned formula f ₀The expression centre frequency, k represents the frequency modulation rate, and the pass of k and bandwidth B is B=kT, and wherein T is for cutting general signal time domain width.

Images