CN106161785B - A kind of smart phone real-time communication method based on hidden voice signal - Google Patents
A kind of smart phone real-time communication method based on hidden voice signal Download PDFInfo
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- CN106161785B CN106161785B CN201610487156.6A CN201610487156A CN106161785B CN 106161785 B CN106161785 B CN 106161785B CN 201610487156 A CN201610487156 A CN 201610487156A CN 106161785 B CN106161785 B CN 106161785B
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04M—TELEPHONIC COMMUNICATION
- H04M1/00—Substation equipment, e.g. for use by subscribers
- H04M1/72—Mobile telephones; Cordless telephones, i.e. devices for establishing wireless links to base stations without route selection
- H04M1/724—User interfaces specially adapted for cordless or mobile telephones
- H04M1/72403—User interfaces specially adapted for cordless or mobile telephones with means for local support of applications that increase the functionality
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B11/00—Transmission systems employing sonic, ultrasonic or infrasonic waves
Abstract
The invention discloses a kind of smart phone real-time communication methods based on hidden voice signal, by utilizing orthogonal frequency division multiplexi modelled signal, determine subcarrier modulation modes, analyze the position that original audio signal determines suitable embedding data packet, adaptively embedding data signal, packet header detection, channel estimation, extract eight step such as signal and data correction, utilize the audio signal being highly easy to get in the masking effect and life of human auditory system, while ensuring not influence human ear audio audio experience in main channel, realize dominant loudspeaker-microphone data hiding communication non-in real time.
Description
Technical field
The invention belongs to acoustic communication technical fields, and in particular to a kind of smart phone based on hidden voice signal is real-time
Communication means.
Background technique
With the prevalence of smart machine, people are widely used these equipment and obtain and propagate information.Meanwhile electronics is wide
The equipment that plate, laptop etc. are equipped with screen and speakers is accused, conveniently information source is had become.Broadband service is public
Point out in the Global Internet phenomenon report of department's Sandvine semiannual period: in north America region, video and voice data stream are occupied
Peak period is more than 70% broadband network flow.Under this trend, it is desirable to watch and (listening to) video (sound in user
Frequently while), the smart machine that can hold to user transmits other useful information.For example, ratio is broadcast live in viewing NBA in football fan
Games-time can receive the background introduction and racing season performance statistics data of sportsman and team on intelligent devices.Existing technology is logical
Often directly display additional information；Or first encode information onto and be then displayed on screen for visual image (such as two dimensional code), then
Image is captured by the smart machine that user holds, and is decoded.The former will will affect the viewing experience of user；It is right
In the shake of camera, the offset of angle on the latter, smart machine, user between screen at a distance from, barrier, relative movement, all
It will affect acquisition of information, the flexibility of communication system caused to substantially reduce.Due to audio signal can by diffraction and reflection around
Barrier propagation is crossed, and is propagated to four sides, therefore, the carrier for using audio signal as additional information can solve the above problem.
This invention address that using the audio signal being highly easy to get in the masking effect and life of human auditory system, research and spy
A kind of communication system that hidden information is transmitted between loudspeaker and mobile microphone of rope.
Human ear is related to the perception of volume and the frequency of voice signal, and most sensitive frequency range is 2~4KHz.Frequency
When higher, only the sound of more louder volume could be discovered by human ear.Meanwhile there is the hearing system of people frequency domain masking and time domain to cover
Cover effect.The former refers in two signals similar in frequency, volume it is bigger will shelter lesser one.The latter refers to when two
When signal almost occurs simultaneously, the signal to give great volume will hinder perception of the people to the smaller signal of volume.Therefore, in order to ensure user
To the audio experience of original audio signal, need to select its signal vehicle frequency.
The communication channel of audio signal includes loudspeaker and microphone, realizes that electric signal is believed to audio signal, audio respectively
Number arrive electric signal conversion.The response frequency range of most of loudspeakers is 50~20000Hz, but different loudspeaker frequencies selects
The property of selecting property decline is different, and can decline to a great extent in high band performance.Microphone also has the property of frequency selective fading, more
Voice signal of the microphone of number smart phone to frequency higher than 17KHz can not respond.And the sound that human ear can be heard
Frequency range is 20~18000Hz, this range has been more than the frequency range that microphone can respond.Therefore, believed using audio
Number additional information that can not perceive of carrying human ear, needs to carry out signal fine design.In practical application, outside noise is dry
It disturbs, the propagation loss of audio signal, code capacity, the power between the robustness of not sentience and the information transmitting of additional signal
The factors such as weighing apparatus, require to be considered.
Summary of the invention
In order to solve the above-mentioned technical problems, the present invention provides a kind of smart phones based on hidden voice signal to lead in real time
The method of letter.
The technical scheme adopted by the invention is that: a kind of smart phone real-time communication method based on hidden voice signal,
Characterized by comprising the following steps:
Step 1: utilizing orthogonal frequency division multiplexi modelled signal；
Step 2: determining subcarrier modulation modes；
Step 3: analysis original audio signal determines the position of suitable embedding data packet；
Step 4: adaptively embedding data signal；
Step 5: packet header detection；
Step 6: channel estimation；
Step 7: extracting signal；
Step 8: data correction.
Preferably, the specific implementation of step 1 includes following sub-step:
Step 1.1: 64 subcarriers of the selection frequency between 8~14.3KHz are used to carry data information, and frequency exists
7 subcarriers between 14.4~15KHz carry control signal；All subcarrier widths are chosen for 100Hz；
Step 1.2: the mode of modulated signal is determined according to the Energy distribution situation of original audio；When original audio is greater than
The spectral energy density of 8KHz is less than 3*10-2When J/Hz, the special shape of ASK is utilized --- on-off keying (OOK) modulates letter
Number, and the part that original audio is more than 8KHz is deleted before embedding data；Otherwise, using EDK come modulated signal, and in insertion number
It is more than the part of 14.3KHz according to preceding deletion original audio；
Step 1.3: the data flow of insertion is divided into several data packets, selection in the first half of duration frequency from
fminIt is increased to fmax, later half is reduced to f in the timeminLinear FM signal as packet header (fmin=17KHz, fmax=
20KHz), and fill one section of 50ms silence period；Data-signal is distributed into each data packet again, frequency of use is
The pilot signal of 14.5KHz is for time selectivity estimation, Doppler frequency estimation；A Duan Te is chosen in the tail portion of marking signal
The signal of measured length is as cyclic prefix, for resisting intersymbol interference and inter-carrier interference.,
Preferably, the specific implementation process of step 2 is: the audio signal of corresponding informance packet, low band audio signal
ESD byBe calculated, the ESD of high band audio signal byIt is calculated；Its
In, l is sampling number in each packet；F (KHz) representation signal frequency；F (f) represents frequency as the amplitude of the signal of f；Δ f (i,
J) frequency range, i.e. f ∈ [f are representedi, fj]；
Default modulator approach is ASK, when meeting Eph> Ehigh, andWhen select EDK for modulator approach (EhighAnd Rhl
Indicate that E is arranged in two measurement threshold values, the present inventionhigh=3*10-2J/Hz,
Preferably, the specific implementation process of step 3 is: being directed to the corresponding audio fragment of each symbol, calculate whole
The energy spectral density E of a frequency band audio signalst, audio signal energy spectral density Esl, high band audio signal energy spectral density Esh,
Calculation method is identical with packet；
Define threshold value Emin, indicate the minimum audio energy spectral density that implant data symbol needs；Work as Est> EminShi Caixiang sound
Otherwise embedding data in frequency segment is embedded in without data.
Preferably, step 4 specific implementation process is:
For the subcarrier that ASK mode is modulated, the energy intensity calculation formula for being embedded in signal is as follows:
For the subcarrier that EDK mode is modulated, the strength calculation formula for being embedded in signal is as follows:
Wherein, β indicates embedment strength coefficient, BsiIt is the Bandwidth adjustment value in EDK, EmaxIt is that measurement insertion signal power spectrum is close
Spend the threshold value of maximum value, EslIndicate the energy spectral density of signal.
Preferably, the specific implementation of step 5 includes following sub-step:
Step 5.1: packet header signal is detected using envelope detection；
Step 5.2: obtaining subcarrier modulation modes.
Preferably, the specific implementation of step 6 includes following sub-step:
Step 6.1: the least square estimation method is used, using in each packet on the corresponding subcarrier of first symbol
Pilot tone, carry out frequency selectivity estimation；
Defining w (n) is ambient noise, and h (n) is channel impulse response, and N is the sample number in each mark, and x (n) is to connect
The signal sequence received；After removing cyclic prefix, receiving end receives in first symbol signal expression are as follows:
By Fourier transformation, y (n) is transformed into frequency domain from time domain, expression formula are as follows:
Y (k)=X (k) * H (k)+W (k) k=0,1 ..., N-1；
The then estimated value of channel impulse response, calculation formula are as follows:
Wherein, Xp(k) pilot frequency sequence, W are indicatedp(k) ambient noise at pilot tone, H are indicatedp(k) indicate that channel is rung at pilot tone
It answers,Indicate evaluated error；
Step 6.2: using the least square estimation method, believed using the pilot tone on the subcarrier of 14.5KHz in each symbol
Number carry out time selectivity estimation and Doppler frequency estimation；
Because of the frequency f of transmitting terminal pilot signalsIt is known that passing through the frequency f of pilot signal in the signal of detection receiving endrJust
The factor of determination of Doppler shift effect can be calculated:And then pass through formula:It calculates
Obtain the frequency deviation of all subcarriers；Here v indicates the aerial spread speed of sound, v0Indicate the movement speed of mobile phone, θ table
Show the angle between loudspeaker and mobile phone moving direction.
Preferably, step 7 specific implementation process is: a length and subcarrier bandwidth are identical " data window ", are responsible for
Intercept centre frequency and the identical data of first sub-carrier frequencies；According to corresponding subcarrier-modulated method, signal is carried out
Demodulation；" data window " moves forward the length of a subcarrier bandwidth later, until the data that are embedded in all subcarriers all by
It extracts.
Preferably, in step 7, since the energy of insertion signal has with the average energy of the audio fragment of corresponding symbol
It closes, is accordingly used in extracting the threshold size of each symbol, be adjusted according to the average energy of audio signal.
Preferably, the specific implementation of step 8 includes following sub-step:
Step 8.1: error correction in symbol；In a symbol, error detection and correction noise is carried out using RS code and is drawn
The mistake risen；Before being RS code by data encoding, other all elements are set by the last one element of original information
Exclusive or value, recipient carry out same xor operation to the decoded data of RS code, the correctness for verify data；
Step 8.2: intersymbol erasure correction；Symbol in packet indicates with cell (i), wherein [1,30] i ∈, cell
(i) (j) indicates the bit on j-th of subcarrier, wherein [1,64] j ∈；The last m symbol in packet is chosen as odd
Even parity check symbol enablesTo each j ∈ [1,60], enableWhen multi-bit error occurs for only one symbol in s relevant symbols, this
The symbol of mistake just passes through other s-1 symbol and is restored.
Compared with the existing technology, the beneficial effects of the present invention are: communication distance and angle are broader, for non-line of sight communication
Environment and equipment mobile robustness are stronger.
Detailed description of the invention
Fig. 1 is the schematic diagram of the embodiment of the present invention.
Specific embodiment
Understand for the ease of those of ordinary skill in the art and implement the present invention, with reference to the accompanying drawings and embodiments to this hair
It is bright to be described in further detail, it should be understood that implementation example described herein is merely to illustrate and explain the present invention, not
For limiting the present invention.
Present invention is primarily based on spatial-acoustic communications, consider human ear and smart machine acoustic characteristic, propose one kind and be based on
The experimental method and system of the smart phone real time communication of hidden voice signal.This method makes full use of the masking of human auditory system to imitate
It should be realized while ensuring not influence human ear audio audio experience in main channel with the audio signal being highly easy to get in life
Real-time non-dominant loudspeaker-microphone data hiding communication.The present invention can be used as existing hidden screen-camera
The supplement of communication system improves rate of data signalling and confidence level.
Method provided by the invention can use computer software technology implementation process.Referring to Fig. 1, one kind provided by the invention
Smart phone real-time communication method based on hidden voice signal, comprising the following steps:
Step 1, using orthogonal frequency division multiplexi modelled signal, specific implementation process is:
Step 1.1,64 subcarriers of the selection frequency between 8~14.3KHz are used to carry data signals, and frequency exists
7 subcarriers between 14.4~15KHz carry control signal, and all subcarrier widths are chosen for 100Hz.
Step 1.2, according to the Energy distribution situation of original audio signal, selection is adjusted every using EDK ASK technology
Signal on a subcarrier；It is data packet by the data stream, each data packet contains 31 symbols (comprising data bit) and 1
A packet header signal for synchronization, and the embedding cycle prefix before each symbol.
The specific implementation process of embodiment is described as follows:
64 subcarriers of the selection frequency between 8~14.3KHz first are used to carry data information, frequency 14.4~
7 subcarriers between 15KHz carry control signal.
Secondly, when spectral energy density of the original audio greater than 8KHz is less than 3*10-2When J/Hz, the special form of ASK is utilized
Formula --- on-off key carrys out modulated signal, and the part that original audio is more than 8KHz is deleted before embedding data；Otherwise, using EDK
Carry out modulated signal, and deletes the part that original audio is more than 14.3KHz before embedding data；
Finally, the data flow of insertion is divided into several data packets by the present invention.Selection frequency in the first half of duration
From being increased to, the linear FM signal being reduced in the later half time fills the silence period of one section of 50ms as packet header.It leads
Frequency is synchronous with receiving end for ofdm signal transmitting terminal.It is chosen in this example, the entire pilot signal duration is 100ms.Again
Data-signal is distributed into each data packet, the pilot signal that frequency of use is 14.5KHz is estimated for time selectivity, is how general
Strangle frequency displacement estimation.The Data Labels duration that length is 100ms is chosen in this example.One section is chosen in the tail portion of marking signal
The signal of specific length is as cyclic prefix, and the duration is 10ms in this example, for resisting intersymbol interference and inter-carrier interference.
Step 2, subcarrier modulation modes are determined, energy point is carried out to audio fragment corresponding with each data packet
Analysis selects subcarrier modulation modes (ASK or EDK) for the data packet；The control of a 14.6KHz is embedded in the packet header of data packet
Signal processed indicates the modulation system that corresponding subcarrier uses.
Specific implementation process is:
Defining l is sampling number in each packet；F (KHz) representation signal frequency；F (f) represents frequency as the width of the signal of f
Degree；Δ f (i, j) represents frequency range, i.e. f ∈ [fi, fj]。
The then audio signal of corresponding informance packet, being averaged energy spectral density (ESD) can be by being calculated.Low frequency section audio letter
Number ESD can be byBe calculated, the ESD of high band audio signal byIt calculates
It arrives.
Default modulator approach is ASK, when meeting Eph> Ehigh, andWhen select EDK for modulator approach.The present embodiment
Middle selection selects Ehigh=3*10-2J/Hz,And the signal of 14.6KHz is embedded in each pilot tone to show selection
Modulator approach.
Step 3, original audio signal is analyzed, determines the position of suitable embedding data packet；It is accorded with to each in data packet
Number corresponding audio fragment carries out energy spectrometer when meeting preset condition, adaptive to the segment in the next steps
Ground embedding data is answered, is otherwise embedded in without data.The control letter of 14.8KHz is embedded in into audio fragment as each
Number, as its whether the label of embedding data.
Specific implementation process is:
For the corresponding audio fragment of each symbol, the energy spectral density E of entire frequency band audio signal is calculatedst, audio
The energy spectral density E of signalsl, high band audio signal energy spectral density Esh, E in calculation method and step 2pt、Epl、EphPhase
Together.Here calculating is directed to audio fragment corresponding with each mark in packet.
Define threshold value Emin, indicate the minimum audio energy spectral density that implant data symbol needs.Only work as Est> EminShi Cai
Otherwise the embedding data into audio fragment is embedded in without data.E is chosen in this examplemin=6*10-3J/Hz.At 14.8KHz
Being implanted into a control signal, whether there is or not insertion signals to indicate this section audio.
Step 4, adaptively embedding data signal；Original audio signal energy is higher, and the intensity for being embedded in signal is bigger, instead
It is lower.
Specific implementation process is:
For the subcarrier that ASK mode is modulated, the energy intensity calculation formula for being embedded in signal is as follows:
For the subcarrier that EDK mode is modulated, the strength calculation formula for being embedded in signal is as follows:
Wherein, β indicates embedment strength coefficient, BsiIt is the Bandwidth adjustment value in EDK, EmaxIt is that measurement insertion signal power spectrum is close
Spend the threshold value of maximum value, EslIndicate the energy spectral density of signal；
In the present embodiment, B is chosensi=20Hz.EmaxIt is the threshold value for measuring insertion signal energy spectral density maximum value, this example
In take Emax=5*10-2J/Hz.When the enhancing of the energy of original audio signal, since insertion signal has had enough robusts
Property, therefore its intensity remains unchanged, and otherwise will likely influence user to the sense of hearing body of original audio signal because noise is excessive
It tests.
For the ease of channel estimation, the energy of transmitting terminal pilot signal must be known to recipient, therefore lead in this example
The energy size of frequency signal takes fixed value.
After embedding data signal, by inverse Fourier transform, it can be sent to by loudspeaker to receiving end.
Step 5, packet header detect, using frequency in packet header 14.6KHz control signal come the tune of determination flag subcarrier
Adjusting method.
Specific implementation process is:
Step 5.1: packet header signal is detected using envelope detection.Theoretically, envelope maximum value it is corresponding be packet header position
It sets.But in practical application, due to the presence of signal ring time and rise time, in the signal of receiving end, near the position of packet header
Envelope size it is very close.This will lead to the synchronous error of at most 5 sampled points, cause unpredicted phase offset.?
In this system, corresponding 4410 sampled points of each symbol, therefore be no more than the timing error sub-carrier signal of 5 sampled points
Amplitude and Energy distribution have little effect.
Step 5.2: obtaining subcarrier modulation modes.After positioning packet header, believed by the control that wherein frequency is 14.6KHz
Number, receiving end can know the modulation system of subcarrier.
Step 6, channel estimation is carried out；Using pectination-bulk hybrid pilot, pass through first symbol pair in data packet first
The pilot tone on subcarrier answered carries out frequency selectivity estimation (FSE)；It recycles in each symbol on 14.5KHz subcarrier
Pilot tone carries out time selectivity estimation (TSE) and Doppler frequency estimation (DFOE).
Specific implementation process is:
Step 6.1: using least-squares estimation (LSE) method, utilize the corresponding son of first symbol in each packet
Pilot tone on carrier wave carries out frequency selectivity estimation (FSE).
Defining w (n) is ambient noise, and h (n) is channel impulse response, and N is the sample number in each mark, and x (n) is to connect
The signal sequence received；After removing cyclic prefix, receiving end receives in first symbol signal expression are as follows:
By Fourier transformation, y (n) is transformed into frequency domain from time domain, expression formula are as follows:
Y (k)=X (k) * H (k)+W (k) k=0,1 ..., N-1；
The then estimated value of channel impulse response, calculation formula are as follows:
Wherein, Xp(k) pilot frequency sequence, W are indicatedp(k) ambient noise at pilot tone, H are indicatedp(k) indicate that channel is rung at pilot tone
It answers,Indicate evaluated error；
In the present embodiment, since the signal for being only more than 8KHz to frequency encodes, outside noise is had little effect,
Therefore the frequency selectivity decline of evaluated error very little, symbol is approximate therewith.
Step 6.2: using least-squares estimation (LSE) method, utilize leading on the subcarrier of 14.5KHz in each symbol
Frequency signal carries out time selectivity estimation (TSE) and Doppler frequency estimation (DFOE).
When receiving end when moving, due to the presence of Doppler effect, the amplitude and phase of channel response in a symbol
It will change.In order to compensate for evaluated error, need to take into account the movement of receiving end.Due to transmitting terminal pilot signal
Frequency fsKnown (14.5KHz) can calculate Doppler's frequency by the frequency fr of pilot signal in the signal of detection receiving end
The factor of determination of inclined effect:And then pass through formula:All sons can be calculated
The frequency deviation of carrier wave.Here v indicates the aerial spread speed of sound, v0Indicate mobile phone movement speed, θ indicate loudspeaker and
Angle between mobile phone moving direction.
After the influence for eliminating Doppler shift, all data-signals can be accurately positioned.
Step 7, signal is extracted, specific implementation process is:
After DFOE, the data of each subcarrier carrying are refined positioning, therefore can be restored using channel estimation
Original signal.
The present invention defines a length and subcarrier bandwidth is identical " data window ", is responsible for interception centre frequency and first
The identical data of sub-carrier frequencies.According to corresponding subcarrier-modulated method, signal is demodulated." data window " forward later
The length of a mobile subcarrier bandwidth, until the data being embedded in all subcarriers are all extracted.Due to being embedded in signal
Energy it is related with the average energy of the audio fragment of corresponding symbol, be accordingly used in extracting the threshold size of each symbol, root
It is adjusted according to the average energy of audio signal.
Step 8, data correction；Data error distribution situation in test data packet repeatedly under the same conditions, it is most of
The mistake of symbol is no more than 3 bits, it may be possible to since the noise in external environment causes；Small part symbol error is more than 10 ratios
It is special, it may be possible to since multipath effect causes, to need to guarantee the reliability of data using more odd encoder in symbol.
Orthogonal error-correcting system is designed, error correction in symbol, intersymbol erasure correction two parts are divided into.The former uses
RS code is detected and is corrected to the error in data due to caused by noise in symbol；For the latter, error correction is completed in symbol
Afterwards, the last m symbol it is known which symbol is insecure, therefore in availability data packet is as even-odd check
Mark carrys out error correction.
Specific implementation process is:
Step 8.1: error correction in symbol.In a symbol, emphasis handles mistake caused by noise.In this example,
RS code is selected to carry out error detection and correction.In the finite field comprising 15 elements, it can correct at mostA mistake member
Element, and detect any combination of at most n-k Error Elements.It is being RS by data encoding to improve error detection capability
Before code, it sets the last one element of original information to the exclusive or value of other all elements.After recipient decodes RS code
Data carry out same xor operation, the correctness for verify data.
Step 8.2: intersymbol erasure correction.The purpose of this step is a large amount of mistakes corrected in a few symbols, these are wrong
Mistake can not be corrected by RS code.Symbol in packet indicates with cell (i), wherein [1,30] i ∈, cell (i) (j) table
Show the bit on j-th of subcarrier, wherein [1,64] j ∈.After the completion of error correction in symbol, the present invention it is known which
Symbol is insecure, therefore can use the reliable symbol of other in packet to reacquire the information in these symbols.
In this example, the last m symbol in packet is chosen as parity check symbol.It enablesTo each j ∈ [1,64], enable
When multi-bit error occurs for only one symbol in s relevant symbols, the symbol of this mistake can be accorded with by other s-1
Number restored.
It should be understood that the part that this specification does not elaborate belongs to the prior art.
It should be understood that the above-mentioned description for preferred embodiment is more detailed, can not therefore be considered to this
The limitation of invention patent protection range, those skilled in the art under the inspiration of the present invention, are not departing from power of the present invention
Benefit requires to make replacement or deformation under protected ambit, fall within the scope of protection of the present invention, this hair
It is bright range is claimed to be determined by the appended claims.
Claims (8)
1. a kind of smart phone real-time communication method based on hidden voice signal, which comprises the following steps:
Step 1: utilizing orthogonal frequency division multiplexi modelled signal；
The specific implementation of step 1 includes following sub-step:
Step 1.1: 64 subcarriers of the selection frequency between 8~14.3KHz are used to carry data information, frequency 14.4~
7 subcarriers between 15KHz carry control signal；All subcarrier widths are chosen for 100Hz；
Step 1.2: the mode of modulated signal is determined according to the Energy distribution situation of original audio；When original audio is greater than 8KHz's
Spectral energy density is less than 3*10-2When J/Hz, the special shape of ASK is utilized --- on-off keying is being embedded in come modulated signal
The part that original audio is more than 8KHz is deleted before data；Otherwise, using EDK come modulated signal, and original is deleted before embedding data
Beginning audio is more than the part of 14.3KHz；
Step 1.3: the data flow of insertion is divided into several data packets, selection within the first half duration frequency from fminIncrease
For fmax, later half is reduced to f in the timeminLinear FM signal as packet header, and fill the silence period of one section of 50ms；Again
Data-signal is distributed into each data packet, the pilot signal that frequency of use is 14.5KHz is estimated for time selectivity, is how general
Strangle frequency displacement estimation；In the signal that one section of specific length is chosen in the tail portion of marking signal as cyclic prefix, done for resisting intersymbol
It disturbs and inter-carrier interference；
Step 2: determining subcarrier modulation modes；
Step 3: analysis original audio signal determines the position of suitable embedding data packet；
Step 4: adaptively embedding data signal；
Step 5: packet header detection；
Step 6: channel estimation；
Step 7: extracting signal；
Step 8: data correction.
2. the smart phone real-time communication method according to claim 1 based on hidden voice signal, which is characterized in that step
Rapid 2 specific implementation process is: the audio signal of corresponding informance packet, the ESD of low band audio signal by
Be calculated, the ESD of high band audio signal byIt is calculated；Wherein, l is sampled point in each packet
Number；F (KHz) representation signal frequency；F (f) represents frequency as the amplitude of the signal of f；Δ f (i, j) represents frequency range, i.e. f ∈
[fi,fj]；
Default modulator approach is ASK, when meeting Eph>Ehigh, andWhen select EDK for modulator approach；Wherein, EhighAnd Rhl
Indicate two measurement threshold values.
3. the smart phone real-time communication method according to claim 1 based on hidden voice signal, which is characterized in that step
Rapid 3 specific implementation process is: being directed to the corresponding audio fragment of each symbol, calculates the power spectrum of entire frequency band audio signal
Density Est, audio signal energy spectral density Esl, high band audio signal energy spectral density Esh, calculation method is identical with packet；
Define threshold value Emin, indicate the minimum audio energy spectral density that implant data symbol needs；Work as Est>EminShi Caixiang audio fragment
Otherwise middle embedding data is embedded in without data.
4. the smart phone real-time communication method according to claim 1 based on hidden voice signal, which is characterized in that step
Rapid 4 specific implementation process is:
For the subcarrier that ASK mode is modulated, the energy intensity calculation formula for being embedded in signal is as follows:
For the subcarrier that EDK mode is modulated, the strength calculation formula for being embedded in signal is as follows:
Wherein, β indicates embedment strength coefficient, BsiIt is the Bandwidth adjustment value in EDK, EmaxIt is to measure insertion signal energy spectral density most
The threshold value being worth greatly, EslIndicate the energy spectral density of signal.
5. the smart phone real-time communication method according to claim 1 based on hidden voice signal, which is characterized in that step
Rapid 5 specific implementation includes following sub-step:
Step 5.1: packet header signal is detected using envelope detection；
Step 5.2: obtaining subcarrier modulation modes.
6. the smart phone real-time communication method according to claim 1 based on hidden voice signal, which is characterized in that step
Rapid 6 specific implementation includes following sub-step:
Step 6.1: using the least square estimation method, utilize leading on the corresponding subcarrier of first symbol in each packet
Frequently, frequency selectivity estimation is carried out；
Defining w (n) is ambient noise, and h (n) is channel impulse response, and N is the sample number in each mark, and x (n) is to receive
Signal sequence；After removing cyclic prefix, receiving end receives in first symbol signal expression are as follows:
By Fourier transformation, y (n) is transformed into frequency domain from time domain, expression formula are as follows:
Y (k)=X (k) * H (k)+W (k) k=0,1 ..., N -1；
The then estimated value of channel impulse response, calculation formula are as follows:
Wherein, Xp(k) pilot frequency sequence, W are indicatedp(k) ambient noise at pilot tone, H are indicatedp(k) channel response at pilot tone is indicated,Indicate evaluated error；
Step 6.2: use the least square estimation method, using the pilot signal on the subcarrier of 14.5KHz in each symbol into
The estimation of row time selectivity and Doppler frequency estimation；
Because of the frequency f of transmitting terminal pilot signalsIt is known that passing through the frequency f of pilot signal in the signal of detection receiving endrIt can meter
Calculate the factor of determination of Doppler shift effect:And then pass through formula:Institute is calculated
There is the frequency deviation of subcarrier；Here v indicates the aerial spread speed of sound, v0Indicate the movement speed of mobile phone, θ indicates loudspeaking
Angle between device and mobile phone moving direction.
7. the smart phone real-time communication method according to claim 1 based on hidden voice signal, which is characterized in that step
Rapid 7 specific implementation process is: a length and subcarrier bandwidth are identical " data window ", are responsible for interception centre frequency and first
The identical data of sub-carrier frequencies；According to corresponding subcarrier-modulated method, signal is demodulated；Due to being embedded in the energy of signal
Amount is related with the average energy of the audio fragment of corresponding symbol, is accordingly used in extracting the threshold size of each symbol, be according to sound
The average energy of frequency signal is adjusted；" data window " moves forward the length of a subcarrier bandwidth later, until all sons
The data being embedded in carrier wave are all extracted.
8. the smart phone real-time communication method according to claim 1 based on hidden voice signal, which is characterized in that step
Rapid 8 specific implementation includes following sub-step:
Step 8.1: error correction in symbol；In a symbol, carried out caused by error detection and correction noise using RS code
Mistake；Before being RS code by data encoding, it sets the last one element of original information to the exclusive or of other all elements
Value, recipient carry out same xor operation to the decoded data of RS code, the correctness for verify data；
Step 8.2: intersymbol erasure correction；Symbol in packet indicates with cell (i), wherein [1,30] i ∈, cell (i)
(j) bit on j-th of subcarrier is indicated, wherein [1,64] j ∈；The last m symbol in packet is chosen as odd even
Checking symbol enablesTo each j ∈ [1,60], enableWhen multi-bit error occurs for only one symbol in s relevant symbols, this
The symbol of mistake just passes through other s-1 symbol and is restored.
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| CN105450312A (en) * | 2014-08-07 | 2016-03-30 | 福建天晴数码有限公司 | Sending method and device for acoustic wave communication |
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