Signal data synchronization method for multi-microphone array

Abstract

The invention provides a signal data synchronization method for a multi-microphone array, and the method comprises the steps: generating a digital synchronization signal through a main control processing unit, generating an analog synchronization signal through a digital-to-analog converter, and transmitting the analog synchronization signal to each microphone array unit; each microphone array unit obtains a respective synchronizing signal and transmits the synchronizing signal to the main control processing unit; the re-sampler adjusts the sampling interval of the synchronizing signal, and the phase discriminator detects the phase difference between the re-sampled synchronizing signal and the local high-frequency synchronizing signal and feeds back the phase difference to the re-sampler until the re-sampled synchronizing signal and the local high-frequency synchronizing signal have the same frequency and keep a stable phase difference; and performing mobile cross-correlation on the resampled synchronizing signal and a local high-frequency synchronizing signal in the delay estimator, and compensating delay deviation through a delayer. And the main control processing unit performs synchronization processing by using the local synchronization signal and the received return synchronization signal, and further adjusts the microphone signal of the array unit to achieve strict sample synchronization.

Description

Technical Field

[0001] The present invention belongs to the technical field of signal transmission, and particularly relates to a signal data synchronization method for a multi-microphone array. Background Art

[0002] Since the microphone array has the characteristic of directional sound pickup, it can effectively suppress the noise interference in non-target directions and is a commonly used noise reduction means. In many application scenarios, multiple arrays need to work together. Currently, the common cooperation method is that each array transmits the processing results to the main control processing unit for fusion, and this kind of fusion at the processing result level does not require strict data synchronization. In addition, there are also some scenarios where comprehensive processing of the signals collected by each array is required, which requires the system to have a strict sample synchronization mechanism. However, since each array has an independent clock circuit and control timing, strict sample synchronization is a challenging problem.

[0003] There are two requirements for the signal data synchronization of multiple arrays: one is the synchronization of the starting moment. Since each array uploads data in frames according to its own control timing when transmitting data to the main control processing unit, it is difficult for the main control unit to determine whether the starting moments of the signal data received from each array at the same time are synchronized. The other is the synchronization of the sampling period. Since each array uses an independent clock circuit, the sampling periods are not exactly the same. Although the deviation in a single period is extremely small, the deviation will become larger and larger after long-term accumulation. If not adjusted in time, it will lead to serious out-of-step. Summary of the Invention

[0004] The purpose of the present invention is to provide a signal data synchronization method for a multi-microphone array, aiming to solve the above problems.

[0005] The present invention is implemented as follows. A signal data synchronization method for a multi-microphone array, the method includes the following steps:

[0006] Step S1: The main control processing unit generates a digital synchronization signal syn(n), generates an analog synchronization signal Syn(t) by a digital-to-analog converter, and sends it to each microphone array unit;

[0007] Step S2: Each microphone array unit samples through its own analog-to-digital converter, obtains its own synchronization signal, and transmits it to the main control processing unit;

[0008] Step S3: The resampler in the main control processing unit adjusts the sampling interval of the synchronization signal, the phase discriminator detects the phase difference between the resampled synchronization signal and the local high-frequency synchronization signal, and feeds it back to the resampler. Through the feedback control mechanism, the sampling interval is continuously adjusted until the resampled synchronization signal is in the same frequency as the local high-frequency synchronization signal and maintains a stable phase difference;

[0009] Step S4: In the delay estimator of the master control processing unit, perform a moving cross-correlation on the resampled synchronization signal and the local high-frequency synchronization signal, and determine the relative time delay d between the two according to the maximum value of the cross-correlation result. k Compensate for the delay deviation through a delay device to complete the synchronization of the starting moment.

[0010] A further technical solution of the present invention is that in the step S1, the synchronization signal syn(n) includes a low-frequency signal syn L (n) and a high-frequency signal syn H (n), and the formula is as follows:

[0011] syn L (n) = A L ·cos(2πf L ·Δt s n)

[0012] syn H (n) = A H ·cos(2πf H ·Δt s n)

[0013] Among them, the low-frequency signal is used to synchronize the starting moment, and its frequency f L is determined according to the maximum deviation of the starting moment. The high-frequency synchronization signal is used to synchronize the sampling interval, and its frequency f H is determined according to the nominal sampling rate. A L and A H are the amplitudes of the low-frequency and high-frequency synchronization signals respectively. Let F L = f L ·Δt s , F H = f H ·Δt s , then the formula can be expressed as:

[0014] syn L (n) = A L ·cos(2πF L n)

[0015] syn H (n) = A H ·cos(2πF H n)

[0016] Add the low-frequency and high-frequency synchronization signals to obtain the synchronization signal syn(n) = syn L (n) + syn H (n).

[0017] A further technical solution of the present invention is: in step S2, the synchronization signal sampled by the kth array unit is recorded as syn k (n k ), the formula is Among them, n k is the sample index of the kth array synchronization signal, and is the low-frequency component amplitude and high-frequency component amplitude of the synchronization signal obtained by the k-th array unit, is the sampling interval of the kth array element, and are the initial phases of the low-frequency synchronization signal and the high-frequency synchronization signal collected by the kth array unit, respectively. The formula can be expressed as

[0018] A further technical solution of the present invention is: in step S3, the sampling interval of the input original signal is set to be a constant The sampling interval of the resampled signal is a function of the sample points, denoted by The mth sample after resampling syn' k (m) Time for in, is the initial moment, and the moment of the mth sample after resampling is the moment of the original signal samples and Between samples, the symbol [x] represents the largest integer not less than x, and the signal value of the sample is obtained by interpolation. Due to the deviation of the sampling interval, syn' k The signal frequency in (n) is related to F L and F H There is a certain deviation, recorded as and So syn' k (n) can be expressed as

[0019] A further technical solution of the present invention is: in the phase detector, the resampled synchronization signal syn' k (n) Synchronize with the local high-frequency signal H (n) and then the trigonometric product and difference expansion can be obtained.

[0020]

[0021] The fourth item reflects the frequency difference and phase difference between the two synchronization signals, whose frequency components are much lower than the first three items. The fourth item is separated by using low-pass filtering and used as the output p(n) of the phase discriminator, that is

[0022]

[0023] A further technical solution of the present invention is that in step S3, the phase discriminator feeds back the output p(n) to the resampler, and adjusts the resampling interval according to p(n) until p(n) is close to 0. At this time, the frequency deviation is close to 0, and the phase deviation is stably maintained at π / 2, that is, the sampling interval synchronization is completed.

[0024] The beneficial effect of the present invention is that the main control processing unit will perform synchronization processing by using the local synchronization signal and the received feedback synchronization signal, and then adjust the microphone signals of the array unit to achieve sampling period synchronization and start time synchronization. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 is a flowchart of the data synchronization method of the present invention;

[0026] Figure 2 is a schematic diagram of the structure and data transmission of the multi-microphone array system of the present invention;

[0027] Figure 3 is a functional block diagram of the main control processing unit of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0028] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0029] A signal data synchronization method for a multi-microphone array provided by the present invention includes the following steps:

[0030] Step S1: The main control processing unit generates a digital synchronization signal syn(n), generates an analog synchronization signal Syn(t) by a digital-to-analog converter, and sends it to each microphone array unit;

[0031] Step S2: Each microphone array unit samples through its own analog-to-digital converter, obtains its own synchronization signal and transmits it to the main control processing unit;

[0032] Step S3: The resampler in the main control processing unit adjusts the sampling interval of the synchronization signal. The phase discriminator detects the phase difference between the resampled synchronization signal and the local high-frequency synchronization signal, and feeds it back to the resampler. Through the feedback control mechanism, the sampling interval is continuously adjusted until the resampled synchronization signal is of the same frequency as the local high-frequency synchronization signal and maintains a stable phase difference.

[0033] Step S4: In the delay estimator of the main control processing unit, perform a moving cross-correlation on the resampled synchronization signal and the local high-frequency synchronization signal, and determine the relative time delay d between the two according to the maximum value of the cross-correlation result. k Compensate for the delay deviation through a delay device to complete the synchronization of the starting moment.

[0034] This solution proposes a signal data synchronization method for a multi-microphone array. As Figure 2 shown, in addition to including multiple microphone array units (hereinafter simply referred to as array units), the system also includes a main control processing unit. The main control processing unit generates a digital synchronization signal syn(n), and then generates an analog synchronization signal Syn(t) through a digital-to-analog converter (D / A), and sends it to each array unit. This signal is received by each array unit and synchronously collected as a digital signal together with several other microphone signals in the array unit. Denote the signal collected by the kth array unit as syn k (n k ) and upload them to the main control processing unit together through the data bus. The main control processing unit will use the local synchronization signal syn(n) and the received feedback synchronization signal syn k (n k ) for synchronization processing, and then adjust the microphone signal of the array unit to make it achieve strict sample synchronization.

[0035] The synchronization signal syn(n) includes two parts, a low-frequency signal syn L (n) and a high-frequency signal syn H (n), as shown in equations (1) respectively:

[0036] syn L (n) = A L ·cos(2πf L ·Δt s n)

[0037] syn H (n) = A H ·cos(2πf H ·Δt s n) (1)

[0038] Among them, the low-frequency synchronization signal is used to synchronize the starting moment, and its frequency f L is determined according to the maximum deviation of the starting moment. For example, if the starting moment deviation is 1 ms, f L can be set to 500 Hz. The high-frequency synchronization signal is used to synchronize the sampling interval, and its frequency f H is determined according to the nominal sampling rate. For example, if the nominal sampling rate is 16 kHz, f H can be set to 8 kHz. A L and A H are the amplitudes of the low-frequency and high-frequency synchronization signals respectively.

[0039] Let F L = f L ·Δt s , F H = f H ·Δt s , then equation (1) can be expressed as equation (2).

[0040] syn L (n) = A L ·cos(2πF L n)

[0041] syn H (n) = A H ·cos(2πF H n) (2)

[0042] Add the low-frequency and high-frequency synchronization signals to obtain the synchronization signal syn(n) = syn L (n) + syn H (n).

[0043] The master control processing unit sends syn(n) to the signal acquisition ends of each array unit. Each array unit samples through its own analog-to-digital converter (A / D) to obtain its own synchronization signal. Denote the synchronization signal sampled by the k-th array unit as syn k (n k ), as shown in equation (3),

[0044]

[0045] where n k is the sample index of the synchronization signal of the k-th array. Since the sampling of each array unit is independent, there is a separate sample index. and are the amplitudes of the low-frequency component and high-frequency component of the synchronization signal obtained by the k-th array unit, is the sampling interval of the k-th array unit. and are the initial phases of the low-frequency synchronization signal and the high-frequency synchronization signal collected by the k-th array unit, respectively. Let Then syn in equation (3) k (n k ) can be expressed as equation (4). Here, it is a symbol representing the product of the sampling frequency f L and the sampling time interval , which can be regarded as a constant.

[0046]

[0047] The signal data of each array unit, including the microphone signal and the synchronization signal, will be transmitted to the main control processing unit to achieve signal data synchronization. As Figure 3 shown, the main control processing unit will perform resampling processing and delay processing on the signal data of each array unit according to the deviation between the local synchronization signal and the feedback synchronization signal of each array unit until the deviation of the synchronization signal is minimized.

[0048] The resampler and the phase discriminator in the main control processing unit are used to achieve sampling period synchronization. The resampler is used to adjust the sampling interval of the signal, and the phase discriminator is used to detect the phase difference between the resampled synchronization signal syn’ k (n) and the local high-frequency synchronization signal syn H (n), and feedback it to the resampler. Through this feedback control mechanism, the sampling interval is continuously adjusted until syn’ k (n) and syn H (n) are of the same frequency and maintain a stable phase difference, that is, the sampling interval synchronization is completed.

[0049] Taking the signal input by the k-th array unit as an example, assume that the sampling interval of the original input signal is a constant The sampling interval of the resampled signal is a sample point function, denoted as The time when the m-th sample syn’ k (m) after resampling is located where, is the initial time, which can be set to 0. Therefore, the time when the m-th sample after resampling is located is between the -th sample and the -th sample of the original signal. The symbol [x] represents the largest integer not less than x, and the signal value of this sample can be obtained through interpolation calculation. Due to the deviation of the sampling interval, the signal frequency in syn’ k (n) has a certain deviation from F L and F H , denoted as and So syn’ k(n) can be expressed as equation (5).

[0050]

[0051] In the phase discriminator, first, the resampled synchronization signal syn’ k (n) is multiplied by the local high-frequency synchronization signal syn H (n). After expanding the product of trigonometric functions into the sum-to-product form, the four added terms in equation (6) can be obtained. The fourth term reflects the frequency difference and phase difference between the two synchronization signals, and its frequency component is much lower than the first three terms. Therefore, the fourth term can be separated by low-pass filtering and used as the output p(n) of the phase discriminator, that is, the result in equation (7).

[0052]

[0053] p(n) will be fed back to the resampler. According to p(n), the resampling interval is adjusted until p(n) is close to 0. At this time, the frequency deviation is close to 0, and the phase deviation is stably maintained at π / 2, that is, the sampling interval synchronization is completed.

[0054] After the sampling period synchronization, the starting time synchronization of the signal is also required. In the delay estimator, the signal syn’ k (n) is subjected to moving cross-correlation, and the relative time delay d k between the two is determined according to the maximum value of the cross-correlation result, and then the delay deviation is compensated by the delay device, and the starting time synchronization can be completed.

[0055] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A signal data synchronization method for a multi-microphone array, characterized in that, The method includes the following steps: Step S1: The main control processing unit generates a digital synchronization signal syn(n), and an analog synchronization signal Syn(t) is generated by a digital-to-analog converter and sent to each microphone array unit; Step S2: Each microphone array unit samples through its respective analog-to-digital converter, obtains its respective synchronization signal, and transmits it to the main control processing unit; Step S3: The resampler in the main control processing unit adjusts the sampling interval of the synchronization signal. The phase discriminator detects the phase difference between the resampled synchronization signal and the local high-frequency synchronization signal, and feeds it back to the resampler. Through the feedback control mechanism, the sampling interval is continuously adjusted until the resampled synchronization signal is of the same frequency as the local high-frequency synchronization signal and maintains a stable phase difference; Step S4: In the delay estimator of the main control processing unit, perform a moving cross-correlation on the resampled synchronization signal and the local high-frequency synchronization signal, and determine the relative time delay d between the two according to the maximum value of the cross-correlation result k , and compensate for the delay deviation through a delay device to complete the synchronization of the starting moment.

2. The signal data synchronization method for a multi-microphone array according to claim 1, characterized in that In the step S1, the synchronization signal syn(n) includes a low-frequency signal syn L (n) and a high-frequency signal syn H (n), and the formula is as follows: syn L y(n) = A L · cos(2πf L · Δt s n) syn H y(n) = A H · cos(2πf H · Δt s n) Among them, the low-frequency signal is used to synchronize the starting moment, and its frequency f L is determined according to the maximum deviation of the starting moment. The high-frequency synchronization signal is used to synchronize the sampling interval, and its frequency f H is determined according to the nominal sampling rate. A L and A H are the amplitudes of the low-frequency and high-frequency synchronization signals respectively. Let F L = f L ·Δt s , F H = f H ·Δt s , then the formula can be expressed as: syn L y(n) = A L ·cos(2πF L n) syn H (n)=A H ·cos(2πF H n) Add the low-frequency and high-frequency synchronization signals to obtain the synchronization signal syn(n) = syn L (n) + syn H (n).

3. A signal data synchronization method for a multi-microphone array according to claim 1, characterized in that In step S2, the synchronization signal sampled by the k-th array unit is denoted as syn k (n k ), and the formula is where n k is the sample index of the k-th array synchronization signal, and are the amplitudes of the low-frequency component and the high-frequency component of the synchronization signal obtained by the k-th array unit, is the sampling interval of the k-th array unit, and are the initial phases of the low-frequency synchronization signal and the high-frequency synchronization signal collected by the k-th array unit respectively. Let Then the formula can be expressed as 4. A signal data synchronization method for a multi-microphone array according to claim 1, characterized in that, In step S3, assume that the sampling interval of the input original signal is a constant The sampling interval of the resampled signal is a function of sample points, denoted as The m-th sample syn’ k at the moment where is where is the initial moment, and the moment where the m-th sample after resampling is located is between the -th sample and -th sample of the original signal. The symbol [x] represents the largest integer not less than x. The signal value of this sample is obtained by interpolation. Due to the deviation of the sampling interval, the signal frequency in syn’ k (n) has a certain deviation from F L and F H which is denoted as and Therefore, syn’ k (n) can be expressed as 5. A signal data synchronization method for a multi-microphone array according to claim 4, characterized in that In the phase discriminator, the resampled synchronization signal syn’ k (n) is multiplied by the local high-frequency synchronization signal syn H (n). After expanding the product of trigonometric functions into sum-to-product form, the formula Among them, the fourth item reflects the frequency difference and phase difference between the two synchronization signals, and its frequency components are much lower than the first three items. The fourth item is separated by low-pass filtering and used as the output p(n) of the phase detector, that is 6. A signal data synchronization method for a multi-microphone array according to claim 5, characterized in that, In step S3, the phase detector feeds the output p(n) back to the resampler, adjusts the resampling interval according to p(n) until p(n) approaches 0. At this time, the frequency deviation approaches 0, and the phase deviation is stably maintained at π / 2, that is, the sampling interval synchronization is completed.

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