CN105450312A - Sending method and device for acoustic wave communication - Google Patents
Sending method and device for acoustic wave communication Download PDFInfo
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- CN105450312A CN105450312A CN201410385343.4A CN201410385343A CN105450312A CN 105450312 A CN105450312 A CN 105450312A CN 201410385343 A CN201410385343 A CN 201410385343A CN 105450312 A CN105450312 A CN 105450312A
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Abstract
The invention discloses a sending method for acoustic wave communication. The sending method includes the following steps of: performing the following treatments on a data unit: setting a check code; modulating the data unit to M carriers according to a preset code rule, wherein the M is a positive integer being greater than or equal to 2, the M carriers meet a pairwise orthogonal relationship, an absolute value of a frequency difference of any two carriers in the M carriers is less than or equal to 22 kHz, and the code rule includes a phase parameter or an amplitude parameter; adding a synchronous code; adding a cyclic prefix; and generating an acoustical signal. The invention also provides a corresponding sending device for acoustic wave communication. The method and device is safe in transmission, a transmission distance can be controlled through regulation of the volume of a loudspeaker during a transmission process; and the anti-interference performance is strong, the signal quality is high, the adaptability is strong, the attenuation is weak, and the adaptability of various terminal devices can be effectively improved.
Description
Technical field
The present invention relates to wireless communication field, the sending method of particularly signal transacting and transmission in a kind of acoustic communication and device.
Background technology
For conventional at present local, near-field communication technology, as bluetooth and WiFi, need communicating pair to match before communicating, and need additional equipment; And NFC/RIFD technology also needs special equipment usually, and be often used for the one-way transmission of data.For the acoustic communication art for transfer of data, conventional is ultrasonic communication, and this also needs extra device just can realize, and this all will cause transmission cost to improve, and is also difficult to guarantee technology efficiency of the practice simultaneously.
At present, the frequency range that general portable set can be play and record is 0 ~ 22KHz.In 0 ~ 2KHz band interference comparatively serious (comprising people's one's voice in speech, the sound etc. of surrounding environment), be unsuitable for transfer of data.The way of frequency range as communication frequency of employing 16KHz ~ 22KHz is there is in prior art, in fact for 16KHz ~ 18KHz frequency range, when playing and record, signal attenuation is serious, due to the microphone of mobile phone and the quality of loud speaker uneven, therefore such sound frequency range can not good adaptive all types of mobile phone, is not also suitable for transfer of data.
One publication technology mentions that data are carried out the frequency of sound wave modulation of 20Hz ~ 20kHz by the mode adopting frequency map to be namely similar to FSK, but for ensureing the transmitting of data, needs the frequency of each transmission to remain on 50ms; Then need to ensure that frequency transmission continues 40ms in another publication technology, and need transmitting terminal synchronous with receiving terminal.Well imagine, when data volume is larger time, the transmission time that such transmission means needs is very large, so its efficiency is lower.
OFDM (OrthogonalFrequencyDivisionMultiplexing) i.e. orthogonal frequency division multiplexi, in fact OFDM is MCM (MultiCarrierModulation), the one of multi-carrier modulation.The main thought of OFDM is: channel is divided into some orthogonal sub-channels, high-speed data signal is converted to parallel low speed sub data flow, is modulated to and transmits on each of the sub-channels.Orthogonal signalling by adopting correlation technique to separate at receiving terminal, can reduce the mutual interference (ICI) between subchannel like this.Signal bandwidth on every sub-channels is less than the correlation bandwidth of channel, therefore every sub-channels can regard flatness decline as, thus can intersymbol interference be eliminated, and due to the bandwidth of every sub-channels be only the sub-fraction of former channel width, channel equalization becomes relatively easy.
OFDM modulation technology has the characteristics such as anti-interference, anti-frequency decay, is generally applied to high frequency, wideband transmit field, and is lessly applied to acoustic communication field.
Summary of the invention
Based on this, need to provide a kind of acoustic communication technical scheme with good terminal adaptability, high-transmission efficiency, low cost input.
For achieving the above object, inventor provide a kind of acoustic communication sending method, comprise step:
One data cell is handled as follows:
Check code is set;
Described data cell is modulated on M carrier wave by pre-arranged code rule, M be more than or equal to 2 positive integer, a described M carrier wave meets the relation of pairwise orthogonal, and in M carrier wave, the absolute value of the frequency-splitting of any two carrier waves is less than or equal to 22kHz; Described coding rule comprises phase parameter or range parameter;
Add synchronous code;
Add Cyclic Prefix;
Generate voice signal.
Further, in described acoustic communication sending method, described data cell " is modulated on M carrier wave by pre-arranged code rule " and specifically comprises by step:
Data cell is converted to one group of sequence of complex numbers by default transformation rule, and from this sequence of complex numbers, choose M plural number by default selection rule, and this M plural number is formed with default composition rule the data group that a length is N with (N-M) individual 0, and N point inverse Fourier transform is done to this data group; Wherein N>M and N=2
i, i is positive integer;
Connect all inverse Fourier transform consequential signals and obtain modulation result signal.
Further, in described acoustic communication sending method, described data cell comprises data length, grouping number or packet numbering, and the numerical value of data length, grouping number or packet numbering is all less than or equal to 255.
Further, in described acoustic communication sending method, the value of M is 2-64, and in M carrier wave, the absolute value range of the frequency-splitting of any two carrier waves is 86Hz-16kHz.
Further, in described acoustic communication sending method, the value of M is 2-16, and in M carrier wave, the absolute value range of the frequency-splitting of any two carrier waves is 750Hz-3kHz.
Further, in described acoustic communication sending method, the frequency of the voice signal that step " generation voice signal " generates is positioned at following ranges:
(93.75*0.9*k-93.75*1.1*k)Hz，
(86.13*0.9*k-86.13*1.1*k)Hz，
(78.13*0.9*k-78.13*1.1*k)Hz，
(62.5*0.9*k-62.5*1.1*k) Hz, or
(43.1*0.9*k-43.1*1.1*k) Hz, wherein k=0,1 ..., 255.
Inventor additionally provides a kind of acoustic communication dispensing device, comprises verification and arranges module, modulation module, synchronous code module, cyclic prefix module and sound generation module;
Described correction verification module is used for arranging check code to data cell;
Described modulation module is for being modulated to M carrier wave by described data cell by pre-arranged code rule, M be more than or equal to 2 positive integer, a described M carrier wave meets the relation of pairwise orthogonal, and in M carrier wave, the absolute value of the frequency-splitting of any two carrier waves is less than or equal to 22kHz; Described coding rule comprises phase parameter or range parameter;
Described synchronous code module is used for adding synchronous code;
Described cyclic prefix module is used for adding Cyclic Prefix;
Described sound generation module is for generating voice signal.
Further, in described acoustic communication dispensing device, described data cell is modulated on M carrier wave by pre-arranged code rule and specifically comprises by modulation module:
Data cell is converted to one group of sequence of complex numbers by default transformation rule, and from this sequence of complex numbers, choose M plural number by default selection rule, and this M plural number is formed with default composition rule the data group that a length is N with (N-M) individual 0, and N point inverse Fourier transform is done to this data group; Wherein N>M and N=2
i, i is positive integer;
Connect all inverse Fourier transform consequential signals and obtain modulation result signal.
Further, in described acoustic communication dispensing device, described data cell comprises data length, grouping number or packet numbering, and the numerical value of data length, grouping number or packet numbering is all less than or equal to 255.
Further, in described acoustic communication dispensing device, the value of M is 2-64, and in M carrier wave, the absolute value range of the frequency-splitting of any two carrier waves is 86Hz-16kHz.
Further, in described acoustic communication dispensing device, the value of M is 2-16, and in M carrier wave, the absolute value range of the frequency-splitting of any two carrier waves is 750Hz-3kHz.
Further, in described acoustic communication dispensing device, the frequency of the voice signal that sound generation module generates is positioned at following ranges:
(93.75*0.9*k-93.75*1.1*k)Hz，
(86.13*0.9*k-86.13*1.1*k)Hz，
(78.13*0.9*k-78.13*1.1*k)Hz，
(62.5*0.9*k-62.5*1.1*k) Hz, or
(43.1*0.9*k-43.1*1.1*k) Hz, wherein k=0,1 ..., 255.
Be different from prior art, technique scheme is easy to use, transmitting procedure without the need to coupling, with biography; Transmission security, transmitting procedure carrys out controls transfer distance by regulating speaker volume; Strong interference immunity, adopt OFDM modulation technology, anti-frequency decay, improves the environment resistant interference performance of system simultaneously; Signal quality is high, strong adaptability, decay more weak, and effectively can improve the adaptability of various terminal equipment, can flexible Application on the terminal equipment with microphone and/or loud speaker, comprise the mobile terminal of Android, ios, windowsphone operating system and the PC etc. of windows platform.
Accompanying drawing explanation
Fig. 1 is the flow chart of acoustic communication sending method described in an embodiment of the present invention;
Fig. 2 is the structural representation of acoustic communication dispensing device described in an embodiment of the present invention.
Description of reference numerals:
21-Data Division module
22-verification arranges module
23-modulation module
24-synchronous code module
25-cyclic prefix module
26-sound generation module
Embodiment
By describe in detail technical scheme technology contents, structural feature, realized object and effect, coordinate accompanying drawing to be explained in detail below in conjunction with specific embodiment.
Referring to Fig. 1, is the flow chart of acoustic communication sending method described in an embodiment of the present invention; Described method comprises the steps:
S11, split data to be sent by preset length condition, obtain some data cells.
In this step, first select or edit particular content to be sent, calculating the length of data to be sent, then with the length being no more than 40 bytes, data to be sent being split according to the setting of system in practical application, obtain some data cells.Follow-up data processing all will be carried out respectively in units of each data cell.When the original length of data to be sent has inherently met preset length condition, this step can have been saved.
S12, check code is arranged to data cell.
In this step, first each data cell after splitting is marked, then in units of 1bit, be arranged at front end data at the end of data cell and divide into groups corresponding bit.By arranging check code, the data demodulates for receiving terminal provides the foundation of redundancy error check.Described verification mode comprises parity check, odd-even difference parity check sum CRC cyclic redundancy check (CRC), can also be that other can reach the conventional method of data check object.
S13, described data cell to be modulated on M carrier wave by pre-arranged code rule.
This step specifically comprises:
Data cell is converted to one group of sequence of complex numbers by default transformation rule, and from this sequence of complex numbers, choose M plural number by default selection rule, and this M plural number is formed with default composition rule the data group that a length is N with (N-M) individual 0, and N point inverse Fourier transform is done to this data group; Wherein N>M and N=2
i, i is positive integer;
Connect all inverse Fourier transform consequential signals and obtain modulation result signal.
Described default transformation rule can be BPSK or QPSK.According to BPSK conversion, then " 0 " in Serial No. be modulated to "-1 ", " 1 " in Serial No. is modulated to " 1 ", thus obtains positive and negative staggered bpsk signal; Change according to QPSK, then " 00 " in sequence is modulated to "-1-i ", " 01 " is modulated to "-1+i ", " 10 " are modulated to " 1-i ", " 11 " are modulated to " 1+i ", thus obtain the QPSK data flow of four phase places, facilitate the carrier modulation of follow-up data, for transfer of data provides safeguard.
Described default selection rule can comprise original position that to choose M plural number from described sequence of complex numbers or choose rule, such as, from sequence of complex numbers i
1-i
10in select 3 plural numbers, can be i
1, i
2, i
3, can be i
5, i
6, i
7, can be i
4, i
8, i
10, also can be i
9, i
3, i
7.
(N-M) individual 0 described in described default composition rule comprises is the position in the data group of N in length, such as should be positioned at the front end that length is the data group of N by (N-M) individual 0, be positioned at the rear end that length is the data group of N, or be positioned at the centre that length is the data group of N.
Preferred default composition rule is will be somebody's turn to do (N-M) individual 0 to be placed in the centre that length is the data group of N.Such as, work as N=10, during M=6, the number of 0 is 4, and according to described preferred composition rule, to be the data group arrangement mode of N be this length: a
1, a
2, a
3, 0,0,0,0, a
4, a
5, a
6.Wherein a
1-a
6for valid data.The usefulness of this preferred composition rule is, in practical operation, part fft converts the result obtained, and to be characterized as centre be maximum positive frequency value and negative frequency value, and two is 0; And being placed in centre by 0, then treatment effect is equivalent to get continuous print-L-+L frequency values, then after the operation of moving 0-22k frequency range, can obtain a continuous print frequency.
Modulation in present embodiment is OFDM modulation in essence, employ 128 subcarriers (i.e. N=128) in its process, carrier spacing Δ f=375Hz, effective sub-carrier number is 8 (i.e. M=8), significant character duration T=2.67ms, signal bandwidth f=3k.
The main implementation procedure of OFDM is based on Fourier transform and inverse transformation.Before inverse Fourier transform operation, also comprise a pretreatment operation in this step, after conversion, also comprise a post-processing operation.Be specially:
To a data cell, serioparallel exchange is carried out in units of a byte, 8bit data by each byte are divided into front and back 4bit, 120 0 form 128 bit one group of data as redundant data are added in the middle of this, then inverse fast Fourier transform is carried out to the data that this group comprises 128 bit, obtain frequency domain data, be completed after frequency domain conversion until all grouped datas, again by each group of data convert, parallel data is converted to the data flow of serial, the each grouping frequency domain data being about to obtain is the data flow of a whole string according to original sequential combination, thus complete OFDM modulation.The 8bit of above-mentioned each byte is the real data source forming effective subcarrier, occupies the transmission time of T=2.67ms in data stream transmission process; 120 0 that add, namely adding 0 of 120bit is frequency aliasing in order to prevent data, constitutes the carrier spacing of Δ f=375Hz in data stream transmission process, can effective separate data byte.
Preferably, the value of M is 2-64, and in M carrier wave, the absolute value range of the frequency-splitting of any two carrier waves is 86Hz-16kHz.
More preferably, the value of M is 2-16, and in M carrier wave, the absolute value range of the frequency-splitting of any two carrier waves is 750Hz-3kHz.
For above-mentioned two preferred versions, be described for K, M get 2 for one-channel signal code check: now transmission rate can think 2K, but along with the raising of M, need to reduce K value and could keep stability, so total speed K*M is also not exclusively proportional to M.Simultaneously along with M increases, computational complexity also increases thereupon.
When M gets 2, be equivalent to serioparallel exchange in units of 2 bit, each 1bit before and after being divided into, in the middle of this, add 126 0 technique effects forming one group of data of 128 bit be, improve the transmission rate of nearly a times than unicast communication, estimation can reach 1.2kbps (when taking BPSK to modulate).
When M gets 16, be equivalent in units of two byte 16bit, each 8bit in front and back, middle 112 0.Its technique effect is, in the computing environment that the computing capabilitys such as mobile device are poor, smoothly can run, and ensure that higher transmission rate, theory can reach 4.8kbps.
When M gets 32, be equivalent in units of 4 byte 32bit, each 16bit in front and back, middle 96 0.Its technique effect is, all higher than the transmission rate of the scheme that M gets 2 or 16, and more stable when transfer voice, and be applicable to the practical scene of the sound device better performances such as such as iphone, theoretical transmission rate can reach 9.6kbps.
When M gets 64, be equivalent in units of 8 byte 64bit, each 32bit in front and back, middle 64 0.In several scheme, transmission rate is the highest, and be applicable to the hardware device customizing high-end microphone, theoretical transmission rate can reach 19.2kbps.
In M carrier wave, the absolute value range of the frequency-splitting of any two carrier waves is relevant with M in fact.Such as, at more than 3kHz, then get the frequency differential ranges (actual spectrum 3kHz-6kHz) of 3kHz, general mobile phone can smooth reception, now, as M=8, just in time obtains minimum interval 375Hz.For some high-end handsets, the spectral range of about 6-8kHz can receive, if now M=8, frequency-splitting maximum absolute value value gets 6kHz, and minimum interval is just in time 750Hz.16kHz is the scope that the hardware device of some special customizations can reach.
Difference on the frequency minimum value 86Hz is that M gets 64, value when maximum frequency difference is 5504.
S14, in data cell, add synchronous code.
Namely add the synchronous code of 7 OFDM symbol compositions in the front end of each packet, synchronous code is according to certain aligned transfer, and the signal be mainly used in when receiving data is synchronous, and sign form is:
P＝[1,0,1,0,-1,0,1,0]；
-P＝[-1,0,-1,0,1,0,-1,0]；
1＝[1,1,1,1,1,1,1,1]。
The use of synchronous code, mainly in order to receiving terminal is when data demodulates, as the foundation of data syn-chronization, channel estimating etc., too increases certain redundancy and the robustness of data simultaneously.
The structure of synchronous code is made up of 7 OFDM symbol, and 7 symbols are respectively [1,0,1,0 ,-1,0,1,0], and [1,0,1,0 ,-1,0,1,0], [-1,0 ,-1,0,1,0 ,-1,0], [-1,0 ,-1,0,1,0 ,-1,0], [1,0,1,0 ,-1,0,1,0], [1,0,1,0 ,-1,0,1,0], [1,1,1,1,1,1,1,1], the sequence of " P, P ,-P ,-P, P, P, 1 " is namely constituted.
In other embodiments, adding of synchronous code also can generate whenever carrying out before voice signal, might not as in the embodiment described in after described data cell " is modulated on M carrier wave by pre-arranged code rule " by step and before step " adds Cyclic Prefix ".
Further, data cell comprises synchronous code, data length, grouping number, packet numbering or real data.Wherein the numerical value of data length, grouping number or packet numbering is all less than or equal to 255.
Wherein, synchronous code FCH is mainly used in receiving terminal to the synchronous of data and channel estimating judgement; The data of a byte length describe the length of the actual data that should send of transmitting terminal; Packet count specifies the total number of packet sending data; Packet numbering specifies the packet numbering of notebook data grouping, for illustration of the physical location residing for this grouped data, carries out arrangement reduction for receiving terminal to data; The real data part of the grouping of transmission, data division saves the actual data content of each group.By the organic assembling of above-mentioned grouping, receiving terminal effectively demodulation can restore the data that transmitting terminal sends, and has corresponding error check ability.
Each data cell after grouping includes the real data part of the packet numbering+grouping of packet count+1 byte of data length+1 byte of synchronous code+1 byte of 7 OFDM symbol length.The parameter of dividing into groups in addition is specially:
Often organize maximum length: 40 OFDM symbol are 40byte;
Often organize maximum total bit number: 40 × 8=320bit.
To the reason that block length scope limits be, in order to simplified communication system in specific implementation process, do not consider sampling frequency synchronization and the carrier frequency synchronization of ofdm system, therefore the length of transfer of data can not be oversize, otherwise can cause error code because error is cumulative.Data are easily interfered and error code in transmitting procedure simultaneously, therefore use transmitted in packets.Through a large amount of actual measurement, when block length is (20 ~ 80) symbol, system most effective, other length also can accept, but are at least less than 240 symbols, otherwise can, because the impact of error code, be difficult to successfully receive.Block length in general communication method is generally long or unrestricted, and final sound may be caused unstable.Present embodiment, by limiting block length, reaches reliable and stable laser propagation effect.
S15, in data cell, add Cyclic Prefix.
The continuous data stream that 128bit is unit can be obtained after completing the OFDM modulation of data, now each 128bit is reintegrated, rear 32bit is wherein copied the front end of adding 128bit stream to, form the continuous data stream of 160bit, complete the circulation of data, namely achieve the interpolation of Cyclic Prefix.
S16, generation voice signal.
By this step, the data flow after above-mentioned coded modulation is modulated on the frequency band that can transmit again, generates voice signal.Its design parameter is: according to sampling thheorem, the sample frequency being not less than data frequency 2 times is adopted to sample to data stream, in order to preferably to data sampling, the sample frequency being not less than 48kHz can be adopted, then the microphone of regular handset and loud speaker is used can to receive good frequency f=3 ~ 7KHz as carrier frequency, then the data obtained sampling are multiplied with carrier signal and obtain frequency band transmission data, namely complete the band modulation of data, thus obtain the audio data stream that can supply transfer voice.The frequency of the voice signal generated in this step is positioned at following ranges:
(93.75*0.9*k-93.75*1.1*k)Hz，
(86.13*0.9*k-86.13*1.1*k)Hz，
(78.13*0.9*k-78.13*1.1*k)Hz，
(62.5*0.9*k-62.5*1.1*k) Hz, or
(43.1*0.9*k-43.1*1.1*k) Hz, wherein k=0,1 ..., 255.
When the voice signal that order generates is positioned at above-mentioned range frequencies, just in time can obtain orthogonality in the conventional sample rate scope of two common sound pick-up outfits.Such as, under 48k sample rate, get the relation that both can form arbitrarily pairwise orthogonal in the first class frequency.
Inventor finds in the process selecting signal frequency range, the frequency range can play due to the loudspeaker of general mobile phone is (0 ~ 22KHz) signal, the frequency range that mobile microphone can be recorded is (0 ~ 22KHz), the frequency range that the microphone of part mobile phone can be recorded is that (0 ~ 9KHz) (known mobile phone has millet 1, Nubia mobile phone), in (0 ~ 3KHz) frequency range, signal is easy to the impact being subject to ambient noise, such as people's one's voice in speech etc.Therefore operable frequency range is (3KHz ~ 22KHz).In addition inventor finds through test, the signal of more than 16KHz mobile phone play and be attenuated in receiving course very seriously, be not therefore suitable for transmission data, therefore operable frequency range is (3KHz ~ 16KHz).If want compatible all mobile phones, so operable frequency range is (3KHz ~ 9KHz).
In addition, study discovery through inventor, the decay formula propagated in atmosphere based on sound is known, and decay mainly comprises launches decay and absorption of air two parts; Under general room temperature and relative humidities, transmission range one timing, 22kHz sharply increases with the transfer voice attenuation rate of upper frequency, therefore in M carrier wave, the absolute value of the frequency-splitting of any two carrier waves should be less than or equal to 22kHz, otherwise is carrying out making sound wave highest frequency more than 22kHz in frequency spectrum shift process.Consider the existence of certain environment noise, for maintaining signal to noise ratio, 16kHz is more optimistic estimated value; When ambient noise is larger, about 3kHz has stronger robustness.
Inventor is when a large amount of actual tests obtains subcarrier spacing Δ f for (86HZ ~ 750HZ), and communication efficiency is better.When lower than 86Hz, between each subcarrier, easily there is spectral interference, cause the error rate to improve.When higher than 750Hz, the utilance of frequency spectrum is lower, and transmission code rate is difficult to improve.The value of effective sub-carrier number N can be obtained by signal bandwidth f and subcarrier spacing Δ f, N=f/ Δ f.
Further, in step S13, in order to improve code check, use multiple carrier signal transmission data simultaneously.In order to avoid the mutual aliasing of intercarrier, choose mutually orthogonal carrier signal.These mutually orthogonal subcarriers meet following formula:
Wherein Tsym represents the signal period.The orthogonal frequency can selected under 48kHz sample frequency has the frequency shown in table 1.Several or the whole Frequency points in frequency 1, frequency 2, frequency 3 or frequency 4 can be selected according to the actual requirements.
The orthogonal frequency (unit Hz) can selected during table 1 sample frequency 48kHz
Again such as, the orthogonal frequency can selected under 44.1kHz sample frequency has the frequency shown in table 2.Several or the whole Frequency points in frequency 1, frequency 2, frequency 3 or frequency 4 can be selected according to the actual requirements.
The orthogonal frequency (unit Hz) can selected during table 2 sample frequency 44.1kHz
The acoustic communication sending method of present embodiment design achieve to data quick, modulate and send accurately and efficiently, the highest transmission rate realizing 2.4kbps in the system adopting BPSK modulation, and the highest transmission rate can reach 4.8kbps in the system adopting QPSK modulation.
Referring to Fig. 2, is the structural representation of acoustic communication dispensing device described in an embodiment of the present invention; Described device comprises Data Division module 21, verification arranges module 22, modulation module 23, synchronous code module 24, cyclic prefix module 25 and sound generation module 26.
Described Data Division module 21, for splitting data to be sent by preset length condition, obtains some data cells.
Described verification arranges module 22 for arranging check code to data cell.
Described modulation module 23 is for being modulated to M carrier wave by described data cell by pre-arranged code rule, M be more than or equal to 2 positive integer, a described M carrier wave meets the relation of pairwise orthogonal, and in M carrier wave, the absolute value of the frequency-splitting of any two carrier waves is less than or equal to 22kHz; Described coding rule comprises phase parameter or range parameter; Specifically comprise:
Data cell is converted to one group of sequence of complex numbers by default transformation rule, and from this sequence of complex numbers, choose M plural number by default selection rule, and this M plural number is formed with default composition rule the data group that a length is N with (N-M) individual 0, and N point inverse Fourier transform is done to this data group; Wherein N>M and N=2
i, i is positive integer.
Connect all inverse Fourier transform consequential signals and obtain modulation result signal.
Described synchronous code module 24 is for adding synchronous code.
Described cyclic prefix module 25 is for adding Cyclic Prefix.
Described sound generation module is for generating voice signal.
The concrete mode that this device realizes acoustic communication sending function is as follows:
First, Data Division module 21, for splitting data to be sent by preset length condition, obtains some data cells.First Data Division module 21 is selected or is edited particular content to be sent, calculates the length of data to be sent, then splits data to be sent with the length being no more than 40 bytes according to the setting of system in practical application, obtains some data cells.Follow-up data processing all will be carried out respectively in units of each data cell.When the original length of data to be sent has inherently met preset length condition.Data Division module 21 and performed function thereof can be saved.
Verification arranges module 22 for arranging check code to a data cell.
First verification arranges module 22 and marks each data cell, then in units of 1bit, is arranged at front end data at the end of data cell and divides into groups corresponding bit.By arranging check code, the data demodulates for receiving terminal provides the foundation of redundancy error check.Described verification mode comprises parity check, odd-even difference parity check sum CRC cyclic redundancy check (CRC), can also be that other can reach the conventional method of data check object.
Modulation module 23 is for being modulated to M carrier wave by described data cell by pre-arranged code rule.Specifically comprise:
Data cell is converted to one group of sequence of complex numbers by default transformation rule, and from this sequence of complex numbers, choose M plural number by default selection rule, and this M plural number is formed with default composition rule the data group that a length is N with (N-M) individual 0, and N point inverse Fourier transform is done to this data group; Wherein N>M and N=2
i, i is positive integer;
Connect all inverse Fourier transform consequential signals and obtain modulation result signal.
Described default transformation rule can be BPSK or QPSK.According to BPSK conversion, then " 0 " in Serial No. be modulated to "-1 ", " 1 " in Serial No. is modulated to " 1 ", thus obtains positive and negative staggered bpsk signal; Change according to QPSK, then " 00 " in sequence is modulated to "-1-i ", " 01 " is modulated to "-1+i ", " 10 " are modulated to " 1-i ", " 11 " are modulated to " 1+i ", thus obtain the QPSK data flow of four phase places, facilitate the carrier modulation of follow-up data, for transfer of data provides safeguard.
Described default selection rule can comprise original position that to choose M plural number from described sequence of complex numbers or choose rule, such as, from sequence of complex numbers i
1-i
10in select 3 plural numbers, can be i
1, i
2, i
3, can be i
5, i
6, i
7, can be i
4, i
8, i
10, also can be i
9, i
3, i
7.
(N-M) individual 0 described in described default composition rule comprises is the position in the data group of N in length, such as should be positioned at the front end that length is the data group of N by (N-M) individual 0, be positioned at the rear end that length is the data group of N, or be positioned at the centre that length is the data group of N.
Preferred default composition rule is will be somebody's turn to do (N-M) individual 0 to be placed in the centre that length is the data group of N.Such as, work as N=10, during M=6, the number of 0 is 4, and according to described preferred composition rule, to be the data group arrangement mode of N be this length: a
1, a
2, a
3, 0,0,0,0, a
4, a
5, a
6.Wherein a
1-a
6for valid data.The usefulness of this preferred composition rule is, in practical operation, part fft converts the result obtained, and to be characterized as centre be maximum positive frequency value and negative frequency value, and two is 0; And being placed in centre by 0, then treatment effect is equivalent to get continuous print-L-+L frequency values, then after the operation of moving 0-22k frequency range, can obtain a continuous print frequency.
The modulation that modulation module 23 carries out is OFDM modulation in essence, employ 128 subcarriers (i.e. N=128) in its process, carrier spacing Δ f=375Hz, effective sub-carrier number is 8 (i.e. M=8), significant character duration T=2.67ms, signal bandwidth f=3k.
The main implementation procedure of OFDM is based on Fourier transform and inverse transformation.Before carrying out inverse Fourier transform operation, modulation module 23 also needs to carry out a pretreatment operation, also comprises a post-processing operation after conversion.Be specially:
To a data cell, serioparallel exchange is carried out in units of a byte, 8bit data by each byte are divided into front and back 4bit, 120 0 form 128 bit one group of data as redundant data are added in the middle of this, then inverse fast Fourier transform is carried out to the data that this group comprises 128 bit, obtain frequency domain data, be completed after frequency domain conversion until all grouped datas, again by each group of data convert, parallel data is converted to the data flow of serial, the each grouping frequency domain data being about to obtain is the data flow of a whole string according to original sequential combination, thus complete OFDM modulation.The 8bit of above-mentioned each byte is the real data source forming effective subcarrier, occupies the transmission time of T=2.67ms in data stream transmission process; 120 0 that add, namely adding 0 of 120bit is frequency aliasing in order to prevent data, constitutes the carrier spacing of Δ f=375Hz in data stream transmission process, can separate data byte effectively.
Preferably, the value of M is 2-64, and in M carrier wave, the absolute value range of the frequency-splitting of any two carrier waves is 86Hz-16kHz.
More preferably, the value of M is 2-16, and in M carrier wave, the absolute value range of the frequency-splitting of any two carrier waves is 750Hz-3kHz.
For above-mentioned two preferred versions, be described for K, M get 2 for one-channel signal code check: now transmission rate can think 2K, but along with the raising of M, need to reduce K value and could keep stability, so total speed K*M is also not exclusively proportional to M.Simultaneously along with M increases, computational complexity also increases thereupon.
When M gets 2, be equivalent to serioparallel exchange in units of 2 bit, each 1bit before and after being divided into, in the middle of this, add 126 0 technique effects forming one group of data of 128 bit be, improve the transmission rate of nearly a times than unicast communication, estimation can reach 1.2kbps (when taking BPSK to modulate).
When M gets 16, be equivalent in units of two byte 16bit, each 8bit in front and back, middle 112 0.Its technique effect is, in the computing environment that the computing capabilitys such as mobile device are poor, smoothly can run, and ensure that higher transmission rate, theory can reach 4.8kbps.
When M gets 32, be equivalent in units of 4 byte 32bit, each 16bit in front and back, middle 96 0.Its technique effect is, all higher than the transmission rate of the scheme that M gets 2 or 16, and more stable when transfer voice, and be applicable to the practical scene of the sound device better performances such as such as iphone, theoretical transmission rate can reach 9.6kbps.
When M gets 64, be equivalent in units of 8 byte 64bit, each 32bit in front and back, middle 64 0.In several scheme, transmission rate is the highest, and be applicable to the hardware device customizing high-end microphone, theoretical transmission rate can reach 19.2kbps.
In M carrier wave, the absolute value range of the frequency-splitting of any two carrier waves is relevant with M in fact.Such as, at more than 3kHz, then get the frequency differential ranges (actual spectrum 3kHz-6kHz) of 3kHz, general mobile phone can smooth reception, now, as M=8, just in time obtains minimum interval 375Hz.For some high-end handsets, the spectral range of about 6-8kHz can receive, if now M=8, frequency-splitting maximum absolute value value gets 6kHz, and minimum interval is just in time 750Hz.16kHz is the scope that the hardware device of some special customizations can reach.
Difference on the frequency minimum value 86Hz is that M gets 64, value when maximum frequency difference is 5504.
Synchronous code module 24 for adding synchronous code in data cell.
Namely add the synchronous code of 7 OFDM symbol compositions in the front end of each packet, synchronous code is according to certain aligned transfer, and the signal be mainly used in when receiving data is synchronous, and sign form is:
P＝[1,0,1,0,-1,0,1,0]；
-P＝[-1,0,-1,0,1,0,-1,0]；
1＝[1,1,1,1,1,1,1,1]。
The use of synchronous code, mainly in order to receiving terminal is when data demodulates, as the foundation of data syn-chronization, channel estimating etc., too increases certain redundancy and the robustness of data simultaneously.
The structure of synchronous code is made up of 7 OFDM symbol, and 7 symbols are respectively [1,0,1,0 ,-1,0,1,0], and [1,0,1,0 ,-1,0,1,0], [-1,0 ,-1,0,1,0 ,-1,0], [-1,0 ,-1,0,1,0 ,-1,0], [1,0,1,0 ,-1,0,1,0], [1,0,1,0 ,-1,0,1,0], [1,1,1,1,1,1,1,1], the sequence of " P, P ,-P ,-P, P, P, 1 " is namely constituted.
Further, data cell comprises synchronous code, data length, grouping number, packet numbering or real data.Wherein the numerical value of data length, grouping number or packet numbering is all less than or equal to 255.
Wherein, synchronous code FCH is mainly used in receiving terminal to the synchronous of data and channel estimating judgement; The data of a byte length describe the length of the actual data that should send of transmitting terminal; Packet count specifies the total number of packet sending data; Packet numbering specifies the packet numbering of notebook data grouping, for illustration of the physical location residing for this grouped data, carries out arrangement reduction for receiving terminal to data; The real data part of the grouping of transmission, data division saves the actual data content of each group.By the organic assembling of above-mentioned grouping, receiving terminal effectively demodulation can restore the data that transmitting terminal sends, and has corresponding error check ability.
Each data cell after grouping includes the real data part of the packet numbering+grouping of packet count+1 byte of data length+1 byte of synchronous code+1 byte of 7 OFDM symbol length.The parameter of dividing into groups in addition is specially:
Often organize maximum length: 40 OFDM symbol are 40byte;
Often organize maximum total bit number: 40 × 8=320bit.
To the reason that block length scope limits be, in order to simplified communication system in specific implementation process, do not consider sampling frequency synchronization and the carrier frequency synchronization of ofdm system, therefore the length of transfer of data can not be oversize, otherwise can cause error code because error is cumulative.Data are easily interfered and error code in transmitting procedure simultaneously, therefore use transmitted in packets.Through a large amount of actual measurement, when block length is (20 ~ 80) symbol, system most effective, other length also can accept, but are at least less than 240 symbols, otherwise can, because the impact of error code, be difficult to successfully receive.Block length in general communication method is generally long or unrestricted, and final sound may be caused unstable.Present embodiment, by limiting block length, reaches reliable and stable laser propagation effect.
OFDM modulation module 25 is for carrying out OFDM modulation to data cell.
In the modulated process of OFDM modulation module 25, employ 128 subcarriers, carrier spacing Δ f=375Hz, effective sub-carrier number is 8, significant character duration T=2.67ms, signal bandwidth f=3k.
The main implementation procedure of OFDM is based on Fourier transform and inverse transformation.In fact, OFDM modulation module 25 also comprised a pretreatment operation before inverse Fourier transform operation, also comprised a post-processing operation after conversion.Be specially:
OFDM modulation module 25 carries out serioparallel exchange to a data cell in units of a byte, 8bit data by each byte are divided into front and back 4bit, 120 0 form 128 bit one group of data as redundant data are added in the middle of this, then inverse fast Fourier transform is carried out to the data that this group comprises 128 bit, obtain frequency domain data, be completed after frequency domain conversion until all grouped datas, again by each group of data convert, parallel data is converted to the data flow of serial, the each grouping frequency domain data being about to obtain is the data flow of a whole string according to original sequential combination, thus complete OFDM modulation.The 8bit of above-mentioned each byte is the real data source forming effective subcarrier, occupies the transmission time of T=2.67ms in data stream transmission process; 120 0 that add, namely adding 0 of 120bit is frequency aliasing in order to prevent data, constitutes the carrier spacing of Δ f=375Hz in data stream transmission process, can effective separate data byte.
Cyclic prefix module 25 is for adding Cyclic Prefix.
The continuous data stream that 128bit is unit can be obtained after completing the OFDM modulation of data, now each 128bit reintegrates by cyclic prefix module 26, rear 32bit is wherein copied the front end of adding 128bit stream to, form the continuous data stream of 160bit, complete the circulation of data, namely achieve the interpolation of Cyclic Prefix.
Sound generation module 26 is for generating voice signal.
Particularly, data flow after above-mentioned process to be modulated on the frequency band that can transmit again and to generate voice signal, the design parameter of its process is: according to sampling thheorem, the sample frequency being not less than data frequency 2 times is adopted to sample to data stream, in order to preferably to data sampling, the sample frequency being not less than 48kHz can be adopted, then the microphone of regular handset and loud speaker is used can to accept good frequency f=3 ~ 7KHz as carrier frequency, then the data obtained sampling are multiplied with carrier signal and obtain frequency band transmission data, namely the band modulation of data is completed, thus obtain the audio data stream that can supply transfer voice.The frequency of the voice signal generated is positioned at following ranges:
(93.75*0.9*k-93.75*1.1*k)Hz，
(86.13*0.9*k-86.13*1.1*k)Hz，
(78.13*0.9*k-78.13*1.1*k)Hz，
(62.5*0.9*k-62.5*1.1*k) Hz, or
(43.1*0.9*k-43.1*1.1*k) Hz, wherein k=0,1 ..., 255.
When the voice signal that order generates is positioned at above-mentioned range frequencies, just in time can obtain orthogonality in the conventional sample rate scope of two common sound pick-up outfits.Such as, under 48k sample rate, get the relation that both can form arbitrarily pairwise orthogonal in the first class frequency.
Inventor finds in the process selecting signal frequency range, the frequency range can play due to the loudspeaker of general mobile phone is (0 ~ 22KHz) signal, the frequency range that mobile microphone can be recorded is (0 ~ 22KHz), the frequency range that the microphone of part mobile phone can be recorded is that (0 ~ 9KHz) (known mobile phone has millet 1, Nubia mobile phone), in (0 ~ 3KHz) frequency range, signal is easy to the impact being subject to ambient noise, such as people's one's voice in speech etc.Therefore operable frequency range is (3KHz ~ 22KHz).In addition inventor finds through test, the signal of more than 16KHz mobile phone play and be attenuated in receiving course very seriously, be not therefore suitable for transmission data, therefore operable frequency range is (3KHz ~ 16KHz).If want compatible all mobile phones, so operable frequency range is (3KHz ~ 9KHz).
In addition, study discovery through inventor, the decay formula propagated in atmosphere based on sound is known, and decay mainly comprises launches decay and absorption of air two parts; Under general room temperature and relative humidities, transmission range one timing, 22kHz sharply increases with the transfer voice attenuation rate of upper frequency, therefore in M carrier wave, the absolute value of the frequency-splitting of any two carrier waves should be less than or equal to 22kHz, otherwise is carrying out making sound wave highest frequency more than 22kHz in frequency spectrum shift process.Consider the existence of certain environment noise, for maintaining signal to noise ratio, 16kHz is more optimistic estimated value; When ambient noise is larger, about 3kHz has stronger robustness.
Inventor is when a large amount of actual tests obtains subcarrier spacing Δ f for (86HZ ~ 750HZ), and communication efficiency is better.When lower than 86Hz, between each subcarrier, easily there is spectral interference, cause the error rate to improve.When higher than 750Hz, the utilance of frequency spectrum is lower, and transmission code rate is difficult to improve.The value of effective sub-carrier number N can be obtained by signal bandwidth f and subcarrier spacing Δ f, N=f/ Δ f.
Further, modulation module 23, in order to improve code check, uses multiple carrier signal transmission data simultaneously.In order to avoid the mutual aliasing of intercarrier, choose mutually orthogonal carrier signal.These mutually orthogonal subcarriers meet following formula:
Wherein Tsym represents the signal period.The orthogonal frequency can selected under 48kHz sample frequency has the frequency shown in table 1.Several or the whole Frequency points in frequency 1, frequency 2, frequency 3 or frequency 4 can be selected according to the actual requirements.
Again such as, the orthogonal frequency can selected under 44.1kHz sample frequency has the frequency shown in table 2.Several or the whole Frequency points in frequency 1, frequency 2, frequency 3 or frequency 4 can be selected according to the actual requirements.
The acoustic communication dispensing device of present embodiment design achieve to data quick, modulate and send accurately and efficiently, the highest transmission rate realizing 2.4kbps in the system adopting BPSK modulation, and the highest transmission rate can reach 4.8kbps in the system adopting QPSK modulation.
It should be noted that, in this article, the such as relational terms of first and second grades and so on is only used for an entity or operation to separate with another entity or operating space, and not necessarily requires or imply the relation that there is any this reality between these entities or operation or sequentially.And, term " comprises ", " comprising " or its any other variant are intended to contain comprising of nonexcludability, thus make to comprise the process of a series of key element, method, article or terminal equipment and not only comprise those key elements, but also comprise other key elements clearly do not listed, or also comprise by the intrinsic key element of this process, method, article or terminal equipment.When not more restrictions, the key element limited by statement " comprising ... " or " comprising ... ", and be not precluded within process, method, article or the terminal equipment comprising described key element and also there is other key element.In addition, in this article, " be greater than ", " being less than ", " exceeding " etc. be interpreted as and do not comprise this number; " more than ", " below ", " within " etc. be interpreted as and comprise this number.
Those skilled in the art should understand, the various embodiments described above can be provided as method, device or computer program.These embodiments can adopt the form of complete hardware embodiment, completely software implementation or the embodiment in conjunction with software and hardware aspect.The hardware that all or part of step in the method that the various embodiments described above relate to can carry out instruction relevant by program has come, described program can be stored in the storage medium that computer equipment can read, for performing all or part of step described in the various embodiments described above method.Described computer equipment, includes but not limited to: personal computer, server, all-purpose computer, special-purpose computer, the network equipment, embedded device, programmable device, intelligent mobile terminal, intelligent home device, wearable intelligent equipment, vehicle intelligent equipment etc.; Described storage medium, includes but not limited to: the storage of RAM, ROM, magnetic disc, tape, CD, flash memory, USB flash disk, portable hard drive, storage card, memory stick, the webserver, network cloud storage etc.
The various embodiments described above describe with reference to the flow chart of method, equipment (system) and computer program according to embodiment and/or block diagram.Should understand can by the combination of the flow process in each flow process in computer program instructions realization flow figure and/or block diagram and/or square frame and flow chart and/or block diagram and/or square frame.These computer program instructions can being provided to the processor of computer equipment to produce a machine, making the instruction performed by the processor of computer equipment produce device for realizing the function of specifying in flow chart flow process or multiple flow process and/or block diagram square frame or multiple square frame.
These computer program instructions also can be stored in can in the computer equipment readable memory that works in a specific way of vectoring computer equipment, the instruction making to be stored in this computer equipment readable memory produces the manufacture comprising command device, and this command device realizes the function of specifying in flow chart flow process or multiple flow process and/or block diagram square frame or multiple square frame.
These computer program instructions also can be loaded on computer equipment, make to perform sequence of operations step on a computing device to produce computer implemented process, thus the instruction performed on a computing device is provided for the step realizing the function of specifying in flow chart flow process or multiple flow process and/or block diagram square frame or multiple square frame.
Although be described the various embodiments described above; but those skilled in the art are once obtain the basic creative concept of cicada; then can make other change and amendment to these embodiments; so the foregoing is only embodiments of the invention; not thereby scope of patent protection of the present invention is limited; every utilize specification of the present invention and accompanying drawing content to do equivalent structure or equivalent flow process conversion; or be directly or indirectly used in other relevant technical fields, be all in like manner included within scope of patent protection of the present invention.
Claims (12)
1. an acoustic communication sending method, comprises step:
One data cell is handled as follows:
Check code is set;
Described data cell is modulated on M carrier wave by pre-arranged code rule, M be more than or equal to 2 positive integer, a described M carrier wave meets the relation of pairwise orthogonal, and in M carrier wave, the absolute value of the frequency-splitting of any two carrier waves is less than or equal to 22kHz; Described coding rule comprises phase parameter or range parameter;
Add synchronous code;
Add Cyclic Prefix;
Generate voice signal.
2., in acoustic communication sending method as claimed in claim 1, described data cell " is modulated on M carrier wave by pre-arranged code rule " and specifically comprises by step:
Data cell is converted to one group of sequence of complex numbers by default transformation rule, and from this sequence of complex numbers, choose M plural number by default selection rule, and this M plural number is formed with default composition rule the data group that a length is N with (N-M) individual 0, and N point inverse Fourier transform is done to this data group; Wherein N>M and N=2
i, i is positive integer;
Connect all inverse Fourier transform consequential signals and obtain modulation result signal.
3., in acoustic communication sending method as claimed in claim 1 or 2, described data cell comprises data length, grouping number or packet numbering, and the numerical value of data length, grouping number or packet numbering is all less than or equal to 255.
4., in acoustic communication sending method as claimed in claim 1 or 2, the value of M is 2-64, and in M carrier wave, the absolute value range of the frequency-splitting of any two carrier waves is 86Hz-16kHz.
5., in acoustic communication sending method as claimed in claim 1 or 2, the value of M is 2-16, and in M carrier wave, the absolute value range of the frequency-splitting of any two carrier waves is 750Hz-3kHz.
6., in acoustic communication sending method as claimed in claim 1 or 2, the frequency of the voice signal that step " generation voice signal " generates is positioned at following ranges:
(93.75*0.9*k-93.75*1.1*k)Hz，
(86.13*0.9*k-86.13*1.1*k)Hz，
(78.13*0.9*k-78.13*1.1*k)Hz，
(62.5*0.9*k-62.5*1.1*k) Hz, or
(43.1*0.9*k-43.1*1.1*k) Hz, wherein k=0,1 ..., 255.
7. an acoustic communication dispensing device, comprises verification and arranges module, modulation module, synchronous code module, cyclic prefix module and sound generation module;
Described correction verification module is used for arranging check code to data cell;
Described modulation module is for being modulated to M carrier wave by described data cell by pre-arranged code rule, M be more than or equal to 2 positive integer, a described M carrier wave meets the relation of pairwise orthogonal, and in M carrier wave, the absolute value of the frequency-splitting of any two carrier waves is less than or equal to 22kHz; Described coding rule comprises phase parameter or range parameter;
Described synchronous code module is used for adding synchronous code;
Described cyclic prefix module is used for adding Cyclic Prefix;
Described sound generation module is for generating voice signal.
8., in acoustic communication dispensing device as claimed in claim 7, described data cell is modulated on M carrier wave by pre-arranged code rule and specifically comprises by modulation module:
Data cell is converted to one group of sequence of complex numbers by default transformation rule, and from this sequence of complex numbers, choose M plural number by default selection rule, and this M plural number is formed with default composition rule the data group that a length is N with (N-M) individual 0, and N point inverse Fourier transform is done to this data group; Wherein N>M and N=2
i, i is positive integer;
Connect all inverse Fourier transform consequential signals and obtain modulation result signal.
9., in acoustic communication dispensing device as claimed in claim 7 or 8, described data cell comprises data length, grouping number or packet numbering, and the numerical value of data length, grouping number or packet numbering is all less than or equal to 255.
10., in acoustic communication dispensing device as claimed in claim 7 or 8, the value of M is 2-64, and in M carrier wave, the absolute value range of the frequency-splitting of any two carrier waves is 86Hz-16kHz.
In 11. acoustic communication dispensing devices as claimed in claim 7 or 8, the value of M is 2-16, and in M carrier wave, the absolute value range of the frequency-splitting of any two carrier waves is 750Hz-3kHz.
In 12. acoustic communication dispensing devices as claimed in claim 7 or 8, the frequency of the voice signal that sound generation module generates is positioned at following ranges:
(93.75*0.9*k-93.75*1.1*k)Hz，
(86.13*0.9*k-86.13*1.1*k)Hz，
(78.13*0.9*k-78.13*1.1*k)Hz，
(62.5*0.9*k-62.5*1.1*k) Hz, or
(43.1*0.9*k-43.1*1.1*k) Hz, wherein k=0,1 ..., 255.
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