CN102904849A - Burst communication system utilizing transient peak energy - Google Patents
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Abstract
Disclosed is a burst communication system utilizing transient peak energy. A transmitter adopts a simplified expanded binary phase shift keying modulation mode, a receiver comprises a receiving antenna, the receiving antenna is connected with an analog receiver, the analog receiver is connected with an analog-to-digital converter, the analog-to-digital converter is connected with an EBPSK (expanded binary phase shift keying) digital modulator, and the EBPSK digital modulator is connected with a frame processor; the analog receiver comprises a pre-amplifier, the pre-amplifier is connected with a frequency mixer, and the frequency mixer is connected with an intermediate-frequency amplifier; and the EBPSK digital modulator comprises a digital impacting filter, the digital impacting filter is connected with a preprocessor, the preprocessor is connected with a return-to-zero decision device, the return-to-zero decision device is connected with a delay calculation module, both the delay calculation module and the preprocessor are connected to a variable delayer, the variable delayer is connected with an integration decision device, the return-to-zero decision device is further connected with a clock generator, the clock generator is connected to the integration decision device, and a frequency synthesizer is respectively connected to the frequency mixer and the clock generator.
Description
Technical field
The invention belongs to digital communication and wireless sensor network technology field, be specifically related to a kind of transient peak Energy Transfer short data of signal in setting up process or hypervelocity burst communication method of small data packets of receiving of utilizing.
Background technology
1, Sensor Network and burst communication
Wireless sensor network (WSN:Wireless Sensor Network) is the important support of Internet of Things, the multi-hop data communication network that normally is made of with the self-organizing form a large amount of automatics that spatially distribute is processed so as to Monitoring Data is sent to receiving center.The node of WSN has also been equipped radio set and microcontroller except being equipped with one or more transducers, size and cost depend on the scale of WSN and the complexity of single-sensor node.Common this WSN node will be powered by minicell, and its time-to-live mainly is subject to the life-span of battery, thus energy-conservation most important for the useful life that prolongs the WSN node, also more meet the demand for development of current pursuit energy-saving and emission-reduction, environmental protection.
Because radio transmitter is the main modular that consumes energy in the WSN node, therefore shorten by fair means or foul the operating time of transmitter, can effectively prolong the work timing of WSN node, and reduce interference for other WSN node and whole sensing network, thereby improve the capacity of whole wireless sensor network.Therefore, WSN wishes that each node can finish data transfer short as far as possible " bursting " in the period.
In addition, have the expert to point out after the scouting of having analyzed external high frequency (HF) frequency range, the impact of perturbation technique on antijam communication: narrow band signal length just is difficult for being intercepted and captured less than 50ms, just is difficult for being directed/locating less than 110ms.And to very high frequency(VHF)/hyperfrequency (VHF/UHF) frequency range, signal length also should be shorter.Therefore, burst communications anti-interference, anti-intercepting and capturing are preferably in the 10ms magnitude finishes communication, and this wishes or require in the lasting moment of signal of communication as far as possible efficiently modulation/transmission efficient is arranged naturally.
2, the extended binary phase shift keying modulation of simplifying
1) availability of frequency spectrum and capacity usage ratio
The broadband wireless business demand of rapid growth has proposed more and more higher requirement to radio communication, has directly caused aerial radio frequency more and more crowded, compresses to greatest extent the wireless transmission frequency spectrum and has important practical significance and direct economic benefit.The availability of frequency spectrum of digital communication system, the numeric code rate that can transmit in the available units frequency band (represents with bps/Hz, but strictly speaking, should be deduction information rate or " only " code check after the chnnel coding) examine, depend primarily on frequency bandwidth shared when the binary data code stream is modulated into transmission frequency range analog carrier.
The capacity usage ratio of wireless communication system can directly be used as reaching required technical indicator or measuring for finishing the required transmitting power of Given task function (W).But because antenna can be introduced extra gain (no matter being transmitting antenna or reception antenna) and with the kind of antenna with form and different, therefore examine more reasonable and direct with received signal to noise ratio (SNR).
2) overall efficiency index
The availability of frequency spectrum and capacity usage ratio are the basic indexs that any communication system section must face, but restricted by classical channel capacity, and the two is difficult to satisfactory to both parties, therefore can come more objective, more fully assessment as overall target with bps/Hz/SNR.Condition certainly should be under identical channel condition, the same error rate and equal clean code check relatively.Its intension is just like pursuing " (Bandwidth-Constrained) steps on the gas (passing high code check) and as far as possible fuel-efficient (saving transmitting power) in the bicycle road ".For the wireless sensor network that is formed by a large amount of sensor node self-organizings, all the more so.Because not hard to imagine, remarkable " traffic rules " (networking agreement) no matter how also is difficult to the old wreck of a group low speed excessive fuel consumption (code speed is low and energy consumption is high) is organized into the traffic and transportation system (sensor network) of high-efficiency long-life.
The communication physical layer of existing WSN node, adopt traditional pseudo random sequence Direct-Spread (DSSS) and classical BPSK/QPSK (binary system/quaternary phase shift keying) modulation, although technical ripe already, power efficiency is the highest in theory, but because spectrum efficiency is low, thereby data rate is low in same spectral bandwidth, be used for this occasion that needs the more frequent sudden transmission of short data of WSN, will cause communication " shaking hands " slow (needing at least 30ms), transfer of data slow (only having 250kbps), and power system capacity low (each receptive WSN nodes of access point institute is far below the agreement nominal value), this just needs the transmitter and receiver of node to start shooting for more time, caused on the contrary thus the energy consumption increase, because in each functional module of WSN node, transmitter is " rich and influential family " of power consumption.
3) binary phase shift keying of expansion modulation
Patent of invention " unified binary quadrature shift keying modulation and demodulation method " (patent No.: ZL200710025203.6), defined binary phase shift keying (the EBPSK:Extended Binary Phase Shift Keying) modulation of class expansion:
s
0(t)＝Asinω
ct，0≤t＜T
Wherein, s
0(t) and s
1(t) represent respectively the modulation waveform of code element " 0 " and " 1 ", ω
cBe carrier angular frequencies; Code-element period T=2 π N/ ω
cContinued N 〉=1 carrier cycle, the modulating time length τ of " 1 " code element=2 π K/ ω
cContinued K＜N carrier cycle, K and N are integer and modulate to guarantee complete cycle, and τ: T=K: N can be described as " modulation duty cycle ".
(1) the phase angle θ of carrier wave keying is less in the formula, and it is poorer that EBPSK detects performance.Therefore simple in order to guarantee demodulation performance and realization, get θ=π, another benefit of bringing thus is to be conducive to receiver to come anti-channel fading and impulse disturbances by amplitude limit.(1) formula is reduced at this moment
s
0(t)＝Asinω
ct，0≤t＜T
As seen the EBPSK modulation signal waveform of this moment is except the section start in data " 1 " has the saltus step of anti-phase and amplitude A+B in short-term, and all the other ones are continuous sine waves.
3, digital shock filter (Digital Impacting Filters)
For " 0 ", asymmetric modulation that " 1 " different wave shape is very little, the classical matched filter that is used for the symmetric modulation waveform and related detecting method are no longer best.In order to improve the demodulation performance for the EBPSK modulation signal, one class infinite impulse response (IIR) digital filter, consisted of by a pair of conjugation zero point and at least two pairs of conjugate poles, the signal carrier frequency is higher than zero frequency but is lower than all pole frequencies, and the close degree of zero frequency and pole frequency will reach 10 of signal carrier frequency at least
-3Magnitude.Thus, this filter is by the precipitous trap-selecting frequency characteristic in its passband center, information modulation (the phase hit that the EBPSK modulation signal can be located in code element " 1 ", cycle disappearance or pulse occur) change obvious and strong parasitic amplitude modulation into and impact, output signal-to-noise ratio is significantly improved, even can be under the situation that signal is flooded fully by noise (SNR＜0) highlight the modulation intelligence of signal with the form of overshoot, therefore be referred to as digital shock filter or EBPSK signal digital booster, but locate then without corresponding wave forms impact in code element " 0 ", (see " impact filtering method that is used for strengthening asymmetric binary modulating signal ", patent of invention publication number: CN101599754) as shown in Figure 1.
Adopt the shock filter of simple zero-3 limit, its transfer function shape is:
Wherein filter coefficient is:
b
0＝1，b
1＝-1.618092409933249，b
2＝0.99990000250000044；
a
1＝-4.5620074920961651，a
2＝9.5862839416819483，a
3＝-11.56698066110164，
a
4＝8.4523528839743243，a
5＝-3.5467147693005732，a
6＝0.6855154433139603。
4, sudden transmission
According to early-stage Study, if EBPSK receiver signal to noise ratio snr＞0dB then adopts the defined EBPSK modulation transmissions of (2) formula code check can reach 1/10 of communication carrier frequency.Therefore, if get 10MHz as carrier frequency (HF frequency range) or intermediate frequency (VHF/UHF frequency range), then in the 10ms burst length, can transmit 10000 bit data, or 625 Chinese characters (16 of each Chinese characters).But this is ideal situation, because on the one hand, also will deduct the shared data bit such as synchronous head, chnnel coding; On the other hand, receiver is set up for catching and growing out of nothing synchronously progressively of burst of data string signal, synchronously or the data bit when not reaching stable state synchronously be difficult for correct the detection, make mistakes many.
For example, on the phase-locked receive of 400MHz frequency range as shown in Figure 2 and the 20MHz intermediate frequency based on the EBPSK demodulator of digital impact filtering, the modulation duty cycle of getting the EBPSK signal waveform is K: N=2: 20, then can get the 1Mbps code check at the 20MHz intermediate frequency.It is 80MHz that EBPSK demodulator analog to digital converter (ADC) sample frequency is set, and namely each intermediate frequency cycle can be adopted 4 points.Because may there be larger time constant in loop filter (LF) and the narrow-band digital shock filter section of the automatic gain of receiver control (AGC) circuit, phase-locked loop, so that each sudden transmission, receive signal section and have one from being established to stable transit time (Fig. 3 is measured waveform), when not reaching certain thresholding height, will adjudicate and make mistakes, therefore must give up transitional code element.Be 3.4ms this transit time under above-mentioned waveform parameter and code check through surveying, therefore adjudicate for correct the reception, abandoned the data of front 4ms.The waste of this code check (or transmission time) and emitted energy only just accounted for 40% in the packet of 10ms in length, and for shorter packet, then this part expense will be more remarkable.Particularly use for typical wireless sensor network, even get sufficiently high 16 ADC of precision, gather a secondary data and also only be equivalent to 1 Chinese character; Once monitor 5 sensing amounts (such as temperature, humidity, pressure, vibrations, displacement etc.), also only have 80 net amount certificates, according to the 1Mbps code check, 80 μ s can pass.But in order to guarantee the shock filter stable output signal, just need to wait for 4ms, cause the huge waste of resource.Therefore, with synchronously, be the key of Effective Raise EBPSK burst communication performance for the fast detecting of the burst signal of EBPSK modulation.
5, quick bit synchronization
In order to reduce the transit time of EBPSK receiver, we disclose a kind of " the binary phase shift keying rapid synchronous method for modulating burst communication of expansion " (patent of invention publication number: CN101895387A), the method has been got rid of analog phase-locked look and the digital phase-locked loop in the receiver, directly will impact envelope and send into respectively rapid adjustment behind threshold detector and the Variable delay device, in 30 code elements, can set up accurately bit synchronization.Based on the EBPSK receiver overall block-diagram of this quick bit synchronization method as shown in Figure 4.
Compare with Fig. 2, because Fig. 4 has removed the slower phase-locked loop of the process of setting up, thereby the transient process of Fig. 5 has shortened a lot.However, owing to after signal amplitude rises near peak value (" A " point), again having occurred near the very low valley point (" B " point) of signal amplitude among Fig. 5, the signal to noise ratio here is minimum, the bunchiness error code easily appears, thereby for safe, usually the working point be selected in and enter after the stable state (after " C " point.And just really enter stable state from the beginning of " D " point), when particularly needing to transmit continuous bit stream or large packet.
Summary of the invention
For realizing, the object of the present invention is to provide a kind of sudden transmission time shorten of complete data packet to the burst communication system that utilizes the transient peak energy of inferior Millisecond.
For solving the problems of the technologies described above, the present invention is achieved through the following technical solutions:
Utilize the burst communication system of transient peak energy, comprise transmitter and receiver, described transmitter adopts the extended binary phase shift keying modulation of simplifying, and the modulating data expression formula is one of following 3 kinds of reduced forms of (2) formula:
1) anti-phase modulation (PRM:Phase Reversal Modulation):
s
0(t)＝sinω
ct，0≤t＜T
2) lack periodic modulation (MCM:Missing Cycle Modulation):
s
0(t)＝sinω
ct，0≤t＜T
3) burst pulse modulation (NPM:Narrow Pulse Modulation) is similar to traditional pulsed radar signal:
s
0(t)＝0，0≤t＜T
Described receiver comprises that one is used for receiving the reception antenna of modulation signal, described reception antenna connects an analog receiver, described analog receiver connects an analog to digital converter, and described analog to digital converter connects an EBPSK digital demodulator, and described EBPSK digital demodulator connects a Frame Handler;
Described analog receiver comprises that one connects the preamplifier of described reception antenna, described preamplifier connects a frequency mixer, described frequency mixer connects one for the intermediate frequency amplifier that connects described analog to digital converter, also comprises a frequency synthesizer, and described frequency synthesizer connects described frequency mixer;
Described EBPSK digital demodulator comprises that one is used for connecting the digital shock filter of described analog to digital converter, described digital shock filter connects a preprocessor, described preprocessor connects a NRZ decision device, described NRZ decision device connects a time delay computing module, described time-delay calculation module and described preprocessor all are connected to a Variable delay device, described Variable delay device connects one for the integration decision device that connects described Frame Handler, in addition, described NRZ decision device also connects a clock generator, described clock generator also is connected to described integration decision device, simultaneously, described frequency synthesizer also is connected to described clock generator.
Further, described digital shock filter is the infinite impulse response structure, is made of a pair of conjugation zero point and at least two pairs of conjugate poles, and the signal carrier frequency is higher than zero frequency but is lower than all pole frequencies, and the close degree of zero frequency and pole frequency will reach 10 of signal carrier frequency at least
-3Magnitude;
Further, described preprocessor is that the parasitic amplitude modulation waveform that described digital shock filter produces is got the envelope absolute value;
Further, described NRZ decision device carries out shaping by threshold judgement to the impact envelope of described preprocessor output, obtain NRZ after, send into simultaneously described bit clock generator and described time-delay calculation module;
Further, when NRZ " 1 " occurring, described time-delay calculation module is measured its high level lasting time, according to the relative position relation that impacts envelope highest point and NRZ " 1 " trailing edge, obtains impacting the amount of delay of envelope;
Further, the initial time of described bit clock generator aligns with the trailing edge of NRZ " 1 ", produces the bit synchronization clock corresponding with transmission code rate;
Further, described Variable delay device is dynamically adjusted the time-delay of impacting envelope according to the measured amount of delay of described time-delay calculation module, the rising edge of bit synchronization clock is alignd with the highest point that impacts envelope, thereby reach bit synchronous purpose;
Further, described integration decision device as time reference, to adjudicating behind the envelope-sampling value integration in the code element, namely demodulates received data sequence with the bit synchronization pulse of described bit clock generator output;
Further, described Frame Handler is to the bit synchronous code stream of bursting of described integration decision device output, utilize 11 Barker codes to carry out with it coherent detection, only detect the extraction of just carrying out valid data information behind 11 Barker code frame heads of " 11100010010 ", this preamble detecting process has been finished abandoning of invalid data and judgement that valid data are initial simultaneously, has realized frame synchronization.
The present invention has following beneficial effect:
1. the phase of bursting, short, anti-intercepting and capturing were strong.Because used receiver need not analog phase-locked look and digital phase-locked loop, only utilize the impact filtering envelope of EBPSK modulation signal in 30 code elements, to set up accurately bit synchronization, thereby the system of originally bursting is operated in the envelope oscillations phase in the EBPSK signal impact filtering response initial segment 0.2ms, therefore the sudden transmission of short data can be (even shorter at inferior Millisecond, if code check is higher) moment finish, so miniature packet is difficult to be intercepted and captured or is disturbed.
2. high, the more environmental protection of system energy efficiency.
1) design of Frame of the present invention has guaranteed that the moment high-amplitude overshoot period that described system takes full advantage of receiver shock filter transient response initial segment carries out bursting of valid data, mean value when this moment, received signal to noise ratio was higher than stable state, the not only transmission of valid data more reliable (or transmitting power can be lower), and the available machine time of transmitter can shorten dramatically, be particularly conducive to the energy-saving and cost-reducing of miniature data collection station and wireless sensor network node etc.;
2) EBPSK is single sine-shaped simple binary constant enveloped modulation, particularly MCM and NPM more on-line operation at the on off state of sine pulse, linearity for the last stage of transmitter power amplifier greatly reduces, and peak power (transient state " electromagnetic pulse " communication) and operating efficiency are higher;
3) no matter whether wireless sensor network node itself or its battery reclaim, the capital affects environment, and the present invention is conducive to prolong the useful life of similar battery, thereby help to reduce the battery consumption, and it is (low in energy consumption to reduce the carbon emission amount, heating must be low, and can suitably reduce battery production).
3. receiver is simpler, general, can be totally digitilized integrated.Receiver of the present invention is owing to having saved analog phase-locked look, the local oscillator that can utilize common crystal to produce replaces the RF Voltage-Controlled Oscillator than complex and expensive, need not carrier synchronization and sample-synchronous, thereby not only totally digitilized integrated demodulator is realized more simply inexpensive, and can directly place the intermediate frequency amplifier output of any communication control processor, versatility is very strong.
4. power system capacity is large, and electromagnetic interference is low.Because sudden transmission time of individual data bag shortens dramatically, thereby the capacity of the multi-user system of organizing in time division multiple access (TDMA) mode greatly increases, otherwise or, the electromagnetic interference in the system between the multi-user can significantly reduce.
Above-mentioned explanation only is the general introduction of technical solution of the present invention, for can clearer understanding technological means of the present invention, and can be implemented according to the content of specification, below with preferred embodiment of the present invention and cooperate accompanying drawing to be described in detail as follows.The specific embodiment of the present invention is provided in detail by following examples and accompanying drawing thereof.
Description of drawings
Accompanying drawing described herein is used to provide a further understanding of the present invention, consists of the application's a part, and illustrative examples of the present invention and explanation thereof are used for explaining the present invention, do not consist of improper restriction of the present invention.In the accompanying drawings:
Fig. 1 is that 3 kinds of EBPSK modulation signals of (4) formula are by the envelope absolute value of output response behind (3) formula shock filter.
Fig. 2 is the EBPSK receiver block diagram that 400MHz frequency range 20MHz intermediate frequency is realized.
Fig. 3 adopts the EBPSK receiver of Fig. 2 for initial fluctuating () and the testing result (descending) of the signal data frame shock filter output envelope of 10ms sudden transmission actual measurement.
Fig. 4 is the overall block-diagram of receiver of the present invention.
Fig. 5 is the envelope absolute value of receiver shock filter output waveform shown in Figure 4, and abscissa is the time among the figure, and ordinate is amplitude.
Fig. 6 is that the realization block diagram of EBPSK modulator: Fig. 9 (a) is anti-phase modulator, and Fig. 9 (b) is for lacking the periodic modulation device, and Fig. 9 (c) is narrow pulse modulator.
Fig. 7 is K: N=2: 20: 3 kinds of time domain waveforms of simplifying the EBPSK modulation.
Fig. 8 is K: N=2: 20: 3 kinds of power spectrum emulation of simplifying the EBPSK modulation.
Fig. 9 is that the demodulation performance that 3 kinds of simplification EBPSK are modulated at additive white Gaussian noise channel compares: the ber curve of Fig. 9 (a) when being K=2; Ber curve when Fig. 9 (b) is K=3 and K=4.
Figure 10 is the sudden transmission frame structure, totally 240.
Figure 11 is the auto-correlation function as 11 Barker codes of frame head.
Figure 12 is receiver implementation result figure shown in Figure 7, and wherein, Figure 12 (a) is the output that impact filtering output waveform takes absolute value; Figure 12 (b) is the impact envelope waveform that obtains after Figure 12 (a) signal waveform low-pass filtering; Figure 12 (c) is the NRZ that obtains after Figure 12 (b) shaping; Figure 12 (d) is the measured amount of delay of time-delay calculation device; Figure 12 (e) is the bit synchronization clock waveform; Figure 12 (f) impacts the waveform of envelope after the Variable delay device is dynamically adjusted.
Figure 13 is the envelope absolute value of transient state EBPSK receiver shock filter output waveform when bursting.
Figure 14 is that transient state is impacted envelope and the effective information comparison diagram that demodulates when bursting, and wherein Figure 14 (a) is that amplify the part of Figure 13, and Figure 14 (b) is the code element of exporting through behind demodulation judgement, the preamble detecting.
Figure 15 is the effective code element contrast before and after the preamble detecting, wherein Figure 15 (a) removes major part to abandon the effective output symbol of position after (only having kept last " 101010 "), and Figure 15 (b) then is the actual valid data output that has detected and removed behind 11 Barker code frame heads " 11100010010 ".
Figure 16 is anti-frequency deviation performance test result of the present invention.
Embodiment
Referring to shown in Figure 5 owing to being the peak value that impacts envelope amplitude in the whole signal transition process near " A " point, therefore near this secured transmission of payload data, not only reliable, and can wait for that receiver impact filtering transient process finishes, thereby also quicker.For example, in Fig. 5, the envelope range value of signal is stabilized in about 14 after " D " point although crossed, and between " E " point and " F " put, the ratio that the envelope range value of signal but all is not less than the signal power at 20, two places was (20/14)
2≈ 2, and be equivalent to signal transmission power is doubled at least (transmitting power of signal can be saved half at least in other words), power efficiency greatly improves, and energy-saving effect is remarkable.And than just starting valid data and also can save at least the transmitter work of half and the time of channel occupancy at " C " point.
Utilize the receiver of Fig. 4, and match with the EBPSK transmission code rate, design efficient Frame (or independent data bag) structure, so that valid data appear near the highest transient peak that receives the response of signal impact filtering, realized namely that thus short packages utilizes the transient peak energy of signal to carry out burst communication.Thereby the signal transmission frame that satisfies described specification requirement structurally will comprise following 3 part substances at least:
1) abandons the position.Referring to shown in Figure 5, the amplitude mean value of (after " D " point) when the sample of signal amplitude of (before " G " point) not yet reaches stable state because the Frame the initial segment, thereby signal to noise ratio is lower, transfer of data is reliable not, gives it up.
2) frame head.Be used for frame synchronization, and the sign valid data is initial.
3) valid data.The data message of actual transmissions.
According to the above-mentioned thinking that relates to, below with reference to the accompanying drawings and in conjunction with the embodiments, describe the present invention in detail.
1.EBPSK modulator
Such as (4a), (4b) with (4c) shown in the formula, the realization block diagram of its modulator is respectively shown in Fig. 6 (a)～(c) respectively for the modulation system expression formula of described PRM, MCM and NPM.
1) the PRM modulator of EBPSK
Such as Fig. 6 (a), comprise sine-wave oscillator, inverter and electronic switch S.Wherein the sine-wave oscillator output frequency is f
cSine wave, be divided into upper and lower two-way, above branch road directly export, below branch road through the anti-phase output of inverter; Two inputs of two branch road connecting electronic switch S, electronic switch S select arbitrary signal in two branch roads as the PRM signal of output; Original transmission information sequence is converted to corresponding pulse train, is used for the selection of described control electronic switch S.For described pulse train, only the initial time in data " 1 " is high level, and the duration is τ; At other constantly, pulse train section keeps low level.And pulse train is when low level, and upper tributary signal is output signal, otherwise lower tributary signal is output signal.
2) the MCM modulator of EBPSK
Such as Fig. 6 (b), except inverter and electronic switch being reduced to a strangler, all the other are identical with the PRM modulator.And strangler is except the time blocking-up of the high level of data pulse string, and all the other times are straight-through.
3) the NPM modulator of EBPSK
Such as Fig. 6 (c), except with the information sequence negate, NPM modulator and MCM modulator are identical.Strangler is except the time blocking-up of the high level of data pulse string, and all the other times are straight-through.
As seen from Figure 7, very simple by the time domain waveform section of the simple special case code element " 1 " of 3 kinds of EBPSK modulation of represented this of (4) formula and " 0 "; As seen from Figure 8, after code-element period T (or N) and modulating range τ (or K) are given, these 3 kinds of EBPSK special cases have identical power spectrum structure and shape, just carrier amplitude is different from the ratio of sidebands levels, and theory analysis shows with Computer Simulation section: for identical code-element period, modulating range is larger, and power spectrum main lobe and secondary lobe section are narrower, but corresponding amplitude is also higher, simultaneously demodulation performance also better (referring to Fig. 9) under certain condition.Shown also that thus EBPSK is modulated at the flexibility of regulating or taking into account the availability of frequency spectrum and capacity usage ratio aspect.
Select the 400MHz working frequency range, the 120 μ s duration of bursting.For the defined anti-phase EBPSK modulation system of (4a) formula, get τ: T=3: 15, IF-FRE f
c=30MHz, then corresponding code check is 2Mbps.
2. sudden transmission frame structure
With the 2Mbps code check 120 μ s that burst, can transmit 120 μ s * 2Mbps=240bit, the design transmission frame-form is wherein just exported envelope and bit synchronous foundation for receiving the signal impact filtering for front 101 as shown in figure 10, do not contain effective data, namely give up after the demodulation; Middle 11 Barker codes " 11100010010 " that adopt are as frame head, and its auto-correlation function has sharp-pointed unimodal characteristic as shown in figure 11, is easy to distinguish with information code; Last 128 data messages that are used for sudden transmission.As seen the effective information (the once non-compression sampling values of 8 16 sensing amounts) of 16 bytes or 8 Chinese characters (2 bytes/every Chinese character) can be transmitted in this system in 120 μ s burst times, the waveform of Figure 12 high order end is seen in the sudden transmission impact filtering response of the whole frame data of one, arrange 128 valid data information wherein to be positioned near its envelope peak, effectively to utilize the transient peak energy of signal.Figure 13 (a) then is that amplify the part corresponding to the frame signal of bursting among Figure 12.
3. receiver structure
Referring to shown in Figure 4, no matter adopt any EBPSK modulation, can utilize the receiver of transient peak energy to be consisted of by analog receiver 10, analog to digital converter 11, EBPSK digital demodulator 12 and Frame Handler 8.Wherein analog receiver is made of with frequency synthesizer 1004 preamplifier 1001, frequency mixer 1002, intermediate frequency amplifier 1003, the high-frequency signal that to modulate from the 400MHz frequency range EBPSK of reception antenna 9 becomes the intermediate-freuqncy signal of 30MHz, gives the EBPSK digital demodulator after the analog to digital converter 11 of 14 precision is converted to digital medium-frequency signal according to the 90MHz sample frequency.
4.EBPSK digital demodulator
Referring to shown in Figure 4, described EBPSK digital demodulator 12 comprises a digital shock filter 1, described digital shock filter 1 connects a preprocessor 2, described preprocessor 2 connects a NRZ decision device 3, described NRZ decision device 3 connects a time delay computing module 4, described time-delay calculation module 4 and described preprocessor 2 all are connected to a Variable delay device 5, and described Variable delay device 5 connects an integration decision device 6.In addition, described NRZ decision device 3 also connects a clock generator 7, and described clock generator 7 also is connected to described integration decision device 6.Simultaneously, the frequency synthesizer in the described analog receiver also is connected to described clock generator 7.Its realization principle and functions of modules are as follows:
1) described digital shock filter 1 adopts the given simple zero-3 limit iir filter of (4) formula to realize, the modulation intelligence that EBPSK modulation signal code element " 1 " is located is outstanding to be the parasitic amplitude modulation impact.
2) described preprocessor 2 is take absolute value first (waveform shown in Figure 14 (a)) to be impacted in the parasitic amplitude modulation that described digital shock filter 1 produces carry out low-pass filtering again, to extract the envelope of the EBPSK signal impact filtering response shown in Figure 14 (b).In the present embodiment, described low-pass filtering adopts finite impulse response (FIR) digital filter, and 4MHz is following to be passband, and 10MHz is above to be stopband.
3) described NRZ decision device 3 utilizes threshold judgement that the impact envelope of described preprocessor 2 outputs is carried out shaping, obtain the NRZ shown in Figure 14 (c) after, send into simultaneously described bit clock generator 7 and described time-delay calculation module 4.Detection threshold is the desirable arithmetic mean that impacts envelope peak and its reference level value (i.e. horizontal line among the figure) shown in Figure 14 (b) usually.When NRZ " 1 " occurring:
1. described time-delay calculation module 4 is measured its high level lasting time (the present embodiment is namely directly counted the sampling number of its high level in the duration), according to the relative position relation that impacts envelope highest point and NRZ " 1 " trailing edge, obtain impacting the amount of delay of envelope, shown in Figure 14 (d);
2. at the trailing edge of NRZ " 1 " the described bit clock generator 7 of resetting, its initial time is alignd with the trailing edge of NRZ " 1 ", produce the bit synchronization clock corresponding with the 2Mbps code check, shown in Figure 14 (e).
4) amount of delay measured according to described time-delay calculation module 4 of described Variable delay device 5 is dynamically adjusted the time-delay of impacting envelope, and the bit synchronization rising edge clock is alignd with impact envelope highest point, shown in Figure 14 (f), thereby reaches bit synchronous purpose.This example utilizes the addressable shift register to realize the Variable delay device, and the address of shift register is exactly the amount of delay that impacts envelope, and the output of shift register then is the content in the register pointed of this address.
5) described integration decision device 6 as time reference, to adjudicating behind the envelope-sampling value integration in the code element, namely demodulates received data sequence with the bit synchronization pulse of described bit clock generator 7 outputs.Because after bit synchronization is set up, impact the peak value of envelope corresponding to the bit synchronization rising edge of a pulse, lower range value is then corresponding to bit synchronization pulse trailing edge, for this reason described integration decision device 6 respectively the rising edge of synchronised clock in place and trailing edge to get a plurality of sampled points cumulative respectively, if 2 accumulated values are more approaching, can judge that this code element is " 0 ", otherwise be " 1 ", can take full advantage of like this characteristics that phase hit that shock filter can make EBPSK modulation is transformed into the high-amplitude pulse, make court verdict more excellent.
5. Frame Handler
Shown in Figure 13 (a), comprised in the output code flow of described EBPSK digital demodulator and abandoned position, frame head and data message, also need to carry out frame for this reason and process.Thereby as shown in Figure 4, described integration decision device 6 connects a Frame Handler 8, the bit synchronous code stream of bursting of 8 pairs of described integration decision device 6 outputs of described Frame Handler, utilize 11 Barker codes " 11100010010 " to carry out with it coherent detection, only detect the extraction of just carrying out valid data information behind these 11 Barker code frame heads, be the valid data output of final extraction shown in Figure 13 (b).This preamble detecting process has been finished abandoning of invalid data in Figure 10 Frame and judgement that valid data are initial simultaneously, has realized frame synchronization.Figure 15 is seen in effective code element contrast before and after the preamble detecting, wherein Figure 15 (a) removes major part to abandon the effective output symbol of position after (only having kept last " 101010 "), and Figure 15 (b) then is the actual valid data output that has detected and removed behind 11 Barker code frame heads " 11100010010 ".By Figure 12 and Figure 13 as seen, institute of the present invention construction data is burst and is abandoned the effect of position in the frame, avoid exactly the unreliable of EBPSK impact filtering response the initial segment low signal-to-noise ratio transition region demodulating data, and valid data are arranged near thereafter the signal transient peak value as far as possible the i.e. the highest zone of signal to noise ratio.
6. anti-frequency deviation performance
The front is mentioned, we require described shock filter 1 to be made of a pair of conjugation zero point and at least two pairs of conjugate poles, and the signal carrier frequency is higher than zero frequency but is lower than all pole frequencies, and the close degree of zero frequency and pole frequency will reach 10 of signal carrier frequency at least
-3Magnitude.Therefore, trap-selecting frequency characteristic that this filter passband center is precipitous, not only can be used for the demodulation of EBPSK modulation signal, and certain frequency locking ability is arranged: as long as the transmitting-receiving frequency skew does not exceed this trap-frequency-selecting scope, native system can be in the situation that there be phase-locked loop to work.For this reason, we are respectively at EBPSK signal(-) carrier frequency f
cCarried out different relative frequency deviation Δ f/f when being respectively 1MHz, 10MHz with 50MHz
cTest, the results are shown in Figure 16.As shown in Figure 16, for different carrier frequency, as relative frequency deviation Δ f/f
c10
-3During magnitude, native system can guarantee at least to transmit continuously 10,000 code elements (the present embodiment only need transmit 240 code elements) and the error code that once causes because of the transmitting-receiving frequency difference just occur.Because common crystal oscillator precision is at least 10
-5Above, therefore even in this burst communication, there is certain transmitting-receiving frequency difference, at least still can reliably carry out static communication, can save phase-locked loop fully.
The above is the preferred embodiments of the present invention only, is not limited to the present invention, and for a person skilled in the art, the present invention can have various modifications and variations.Within the spirit and principles in the present invention all, any modification of doing, be equal to replacement, improvement etc., all should be included within protection scope of the present invention.
Claims (2)
1. utilize the burst communication system of transient peak energy, comprise transmitter and receiver, described transmitter adopts the extended binary phase shift keying modulation of simplifying, and the modulating data expression formula is one of following 3 kinds of forms:
1) anti-phase modulation
s
0(t)＝sinω
ct，0≤t＜T
2) lack periodic modulation
s
0(t)＝sinω
ct，0≤t＜T
3) burst pulse modulation
s
0(t)＝0，0≤t＜T
Wherein, s
0(t) and s
1(t) represent respectively the modulation waveform of code element " 0 " and " 1 ", T is code-element period, and τ is the keying modulation period, ω
cAngular frequency for modulated carrier;
It is characterized in that:
Described receiver comprises that one is used for receiving the reception antenna (9) of modulation signal, described reception antenna (9) connects an analog receiver (10), described analog receiver (10) connects an analog to digital converter (11), described analog to digital converter (11) connects an EBPSK digital demodulator (12), and described EBPSK digital demodulator (12) connects a Frame Handler (8);
Described analog receiver (10) comprises that one connects the preamplifier (1001) of described reception antenna (9), described preamplifier (1001) connects a frequency mixer (1002), described frequency mixer (1002) connects one for the intermediate frequency amplifier (103) that connects described analog to digital converter (11), also comprise a frequency synthesizer (1004), described frequency synthesizer (1004) connects described frequency mixer (1002);
Described EBPSK digital demodulator (12) comprises that one is used for connecting the digital shock filter (1) of described analog to digital converter (11), described digital shock filter (1) connects a preprocessor (2), described preprocessor (2) connects a NRZ decision device (3), described NRZ decision device (3) connects a time delay computing module (4), described time-delay calculation module (4) and described preprocessor (2) all are connected to a Variable delay device (5), described Variable delay device (5) connects one for the integration decision device (6) that connects described Frame Handler (8), in addition, described NRZ decision device (3) also connects a clock generator (7), described clock generator (7) also is connected to described integration decision device (6), simultaneously, described frequency synthesizer (1004) also is connected to described clock generator (7).
2. the burst communication system that utilizes the transient peak energy according to claim 1 is characterized in that:
1) described digital shock filter (1) is the infinite impulse response structure, consisted of by a pair of conjugation zero point and at least two pairs of conjugate poles, the signal carrier frequency is higher than zero frequency but is lower than all pole frequencies, and the close degree of zero frequency and pole frequency will reach 10 of signal carrier frequency at least
-3Magnitude;
2) described preprocessor (2) is that the parasitic amplitude modulation waveform that described digital shock filter (1) produces is got the envelope absolute value;
3) described NRZ decision device (3) carries out shaping by threshold judgement to the impact envelope of described preprocessor (2) output, obtain NRZ after, send into simultaneously described bit clock generator (7) and described time-delay calculation module (4);
4) when NRZ " 1 " occurring, described time-delay calculation module (4) is measured its high level lasting time, according to the relative position relation that impacts envelope highest point and NRZ " 1 " trailing edge, obtains impacting the amount of delay of envelope;
5) initial time of described bit clock generator (7) aligns with the trailing edge of NRZ " 1 ", produces the bit synchronization clock corresponding with transmission code rate;
6) described Variable delay device (5) is dynamically adjusted the time-delay of impacting envelope according to the measured amount of delay of described time-delay calculation module (4), the rising edge of bit synchronization clock is alignd with the highest point that impacts envelope, thereby reach bit synchronous purpose;
7) described integration decision device (6) as time reference, to adjudicating behind the envelope-sampling value integration in the code element, namely demodulates received data sequence with the bit synchronization pulse of described bit clock generator (7) output;
8) described Frame Handler (8) is to the bit synchronous code stream of bursting of described integration decision device (6) output, utilize 11 Barker codes to carry out with it coherent detection, only detect the extraction of just carrying out valid data information behind 11 Barker code frame heads of " 11100010010 ", this preamble detecting process has been finished abandoning of invalid data and judgement that valid data are initial simultaneously, has realized frame synchronization.
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| CN106169949A (en) * | 2016-08-22 | 2016-11-30 | 江苏理工学院 | Broadband adaptive extraction device and method for baseband signal bit synchronous clock |
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| CN105099977A (en) * | 2014-05-23 | 2015-11-25 | 中兴通讯股份有限公司 | Communicating method and communicating system based on EBPSK |
| WO2015176597A1 (en) * | 2014-05-23 | 2015-11-26 | 中兴通讯股份有限公司 | Ebpsk-based communication method and system |
| CN106169949A (en) * | 2016-08-22 | 2016-11-30 | 江苏理工学院 | Broadband adaptive extraction device and method for baseband signal bit synchronous clock |
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| CN112653642A (en) * | 2019-10-10 | 2021-04-13 | 华东交通大学 | Method for realizing peak energy burst communication based on EBPSK modulation |
| RU2776968C1 (en) * | 2021-04-14 | 2022-07-29 | Федеральное государственное бюджетное образовательное учреждение высшего образования "Майкопский государственный технологический университет" | Digital signal demodulator with multiple phase shift keying |
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