A timing recovery method and device for UWB

Abstract

The present invention provides a timing recovery method and device for UWB, the method comprising: receiving high sampling rate multi-channel ADC data, controlling the time of inserting new multi-channel ADC data by read enable; adjusting the rate of the multi-channel ADC data at regular intervals; despreading the leading sequence by using the IQ data after interpolation and carrier recovery, performing synchronous capture to extract the code chip synchronization position information; obtaining the peak energy information by the code chip synchronization position information, and performing crystal oscillator deviation detection; dynamically adjusting the bandwidth, capturing and locking the crystal oscillator deviation value; controlling the interpolation numerical control oscillator according to the crystal oscillator deviation value, generating a timing error value and an integer time indication pulse for interpolation; using the timing error value and the integer time indication pulse to perform real-time interpolation filtering on the IQ data, and recovering the ideal data of the best sampling point. The timing recovery method and device for UWB provided by the present invention effectively improves the estimation accuracy of the timing error and can converge quickly.

Description

Technical Field

[0001] The present invention relates to the technical field of ultra-wideband technology, and in particular to a timing recovery method and device for UWB. Background Art

[0002] With the development of communication technology, UWB (ultra-wideband) technology has been widely recognized for its high-speed transmission and positioning capabilities. Compared with other communication technologies, it has many advantages such as low power consumption, high-speed transmission, high positioning accuracy, strong anti-multipath capability, and high security. However, the high-bandwidth characteristics of UWB put forward higher requirements on the communication system using this technology. The analog end needs a high-speed ADC to sample the RF signal, and the digital end uses a high-speed ADC to sample data for high-reliability and low bit error rate reception. Since the crystal oscillators at both ends of the transmitter and receiver cannot be completely synchronized, it is necessary to perform sampling point timing recovery on the ADC sampling, otherwise it will seriously affect the system performance parameters.

[0003] The traditional timing error recovery method can be an analog method based on a phase-locked loop to adjust the ADC clock. However, this method is gradually being eliminated in the digitalization of communications.

[0004] Therefore, it is necessary to provide a timing recovery method and device for UWB to effectively solve the above problems. Summary of the invention

[0005] In view of the problems and shortcomings of the prior art, the present invention provides a timing recovery method and device for UWB, which effectively improves the estimation accuracy of the timing error and can converge quickly.

[0006] An embodiment of the present invention provides a timing recovery method for UWB, the method comprising:

[0007] Receive high sampling rate multi-channel ADC data and control the time to insert new multi-channel ADC data through read enable;

[0008] Regularly adjusting the rate of the multi-channel ADC data;

[0009] Despread the pilot sequence using the interpolated and carrier-recovered IQ data, perform synchronization capture, and extract the chip synchronization position information;

[0010] Obtain peak energy information through the chip synchronization position information to perform crystal oscillator deviation detection;

[0011] Dynamically adjust bandwidth, capture and lock the first crystal oscillator deviation value;

[0012] Controlling a numerically controlled oscillator according to the first crystal oscillator deviation value to generate a timing error value and an integer time indication pulse for interpolation;

[0013] Using the timing error value and the integer time indication pulse to perform real-time interpolation filtering on the IQ data to restore the ideal data of the best sampling point;

[0014] The first crystal oscillator deviation value is calculated by the following formula:

[0015]

[0016] in, is the first crystal oscillator deviation value, is the update period, arctan is the inverse tangent function, and Respectively in After time despreading Luhe Road data, is the leading symbol period.

[0017] Preferably, the sampling rate of the multi-channel ADC data is 1 Gsps, and the multi-channel is 8 channels.

[0018] Preferably, the ADC data sampling rate is restored according to the crystal oscillator deviation direction and the timing adjustment indication pulse, and the timing adjustment indication pulse is obtained by accumulating integer time indication pulses.

[0019] Preferably, all cached data are synchronously updated in each clock cycle, and new data sequentially overwrite old data, and then output to the interpolation filter, which selects different cached data according to the crystal oscillator offset direction and the integer indication pulse.

[0020] Preferably, the cache data includes a clock rate and a rate between channels.

[0021] Preferably, loop filtering is performed on the first crystal oscillator deviation value to obtain a second crystal oscillator deviation value, and the second crystal oscillator deviation value is calculated by the following formula:

[0022]

[0023] in, is the second crystal oscillator deviation value after loop filtering of the current symbol, Represents the current symbol filter loop coefficient, It is the crystal oscillator deviation value after loop filtering of the previous symbol.

[0024] Preferably, the timing error value is calculated by the following formula:

[0025]

[0026] in, Indicates the maximum count integer value, represents the phase conversion factor, Indicates crystal oscillator deviation value, The output range is ,when Changes from one direction to 0 or from the other direction to , Will restart from 0 or Start counting, at this time the interpolation numerically controlled oscillator will output integer time indication pulses to the data buffer unit, and the data buffer unit adjusts the channel data.

[0027] Preferably, the interpolation filtering is calculated by the following formula:

[0028]

[0029] in, The symbol means to take the first value that is smaller than the symbol. The symbol means to take the first value greater than the value inside the symbol. represents the ideal sampling point value, is the previous sampling point of the interpolation filter input. is the next sampling point of the interpolation filter input. The data is restored from the best sampling point.

[0030] The embodiment of the present invention further provides a timing recovery device for UWB, the device comprising:

[0031] The first level buffer is used to receive high sampling rate multi-channel ADC data and control the time of inserting new multi-channel ADC data through read enable;

[0032] A second level buffer, which is used to regularly adjust the rate of the multi-channel ADC data;

[0033] A synchronization module, which uses the IQ data after interpolation and carrier recovery to despread the leading sequence, perform synchronization capture and extract the chip synchronization position information;

[0034] A crystal oscillator deviation detector, which is used to obtain peak energy information through the chip synchronization position information and perform crystal oscillator deviation detection;

[0035] A loop filter, which is used to dynamically adjust the bandwidth, capture and lock the first crystal oscillator deviation value;

[0036] An interpolation digitally controlled oscillator, which is used to control a digitally controlled oscillator according to the first crystal oscillator deviation value to generate a timing error value and an integer time indication pulse for interpolation;

[0037] An interpolation filter, which uses the timing error value and the integer time indication pulse to perform real-time interpolation filtering on the IQ data to restore the ideal data of the best sampling point;

[0038] The first crystal oscillator deviation value is calculated by the following formula:

[0039]

[0040] in, is the first crystal oscillator deviation value, is the update period, arctan is the inverse tangent function, and Respectively in After time despreading Luhe Road data, is the leading symbol period.

[0041] Compared with the prior art, the technical solution of the embodiment of the present invention has the following beneficial effects:

[0042] The embodiment of the present invention provides a timing recovery method and device for UWB, the method comprising: receiving high sampling rate multi-channel ADC data, and controlling the time of inserting new multi-channel ADC data through read enable; adjusting the rate of the multi-channel ADC data at a fixed time; despreading the leading sequence by using the IQ data after interpolation and carrier recovery, and performing synchronous capture to extract the code chip synchronization position information; obtaining the peak energy information through the code chip synchronization position information, and performing crystal oscillator deviation detection; dynamically adjusting the bandwidth, capturing and locking the first crystal oscillator deviation value; controlling the interpolation numerically controlled oscillator according to the first crystal oscillator deviation value, and generating a timing error value and an integer time indication pulse for interpolation; using the timing error value and the integer time indication pulse to perform real-time interpolation filtering on the IQ data, and recovering the ideal data of the best sampling point, thereby effectively improving the estimation accuracy of the timing error and enabling rapid convergence;

[0043] Furthermore, at high sampling rates, not much storage resources need to be consumed, and the clock frequency is low, which reduces the timing error estimation resources;

[0044] Furthermore, the method significantly improves the receiving sensitivity in demodulation performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following is a brief introduction to the drawings required for use in the embodiments or the prior art descriptions. Obviously, the drawings described below are some embodiments of the present invention, not all embodiments. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative labor.

[0046] Figure 1 A flowchart of a timing recovery method for UWB according to a preferred embodiment of the present invention;

[0047] Figure 2 The figure is a schematic structural diagram of a timing recovery device for UWB according to a preferred embodiment of the present invention. DETAILED DESCRIPTION

[0048] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0049] The technical solution of the present invention is described in detail with specific embodiments below. The following specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described in detail in some embodiments.

[0050] In view of the problems and shortcomings of the prior art, the present invention provides a timing recovery method and device for UWB, which effectively improves the estimation accuracy of the timing error and can converge quickly.

[0051] Figure 1 FIG. 1 is a flow chart of a timing recovery method for UWB according to a preferred embodiment of the present invention. Figure 1 , a timing recovery method for UWB, the method comprising:

[0052] Step S101: receiving high sampling rate multi-channel ADC (Analog-to-Digital Converter) data, and controlling the time of inserting new multi-channel ADC data through read enable;

[0053] Step S102: regularly adjusting the rate of the multi-channel ADC data;

[0054] Step S103: Despread the preamble sequence using the interpolated and carrier-recovered IQ data, perform synchronization capture, and extract chip synchronization position information;

[0055] Step S104: obtaining peak energy information through the chip synchronization position information and performing crystal oscillator deviation detection;

[0056] Step S105: dynamically adjusting the bandwidth, capturing and locking the first crystal oscillator deviation value;

[0057] Step S106: controlling a numerically controlled oscillator according to the first crystal oscillator deviation value to generate a timing error value and an integer time indication pulse for interpolation;

[0058] Step S107: using the timing error value and the integer time indication pulse to perform real-time interpolation filtering on the IQ data to restore the ideal data of the best sampling point;

[0059] The first crystal oscillator deviation value is calculated by the following formula:

[0060]

[0061] in, is the first crystal oscillator deviation value, is the update period, arctan is the inverse tangent function, and Respectively in After time despreading Luhe Road data, is the leading symbol period.

[0062] Specifically, in step S101, the first-level buffer is used to receive high-sampling-rate multi-channel ADC data, the ADC sampling rate is 1Gsps, and the 8-channel IQ sampling data is connected to the first-level buffer after the pre-stage gain adjustment and channel filtering. The first-level buffer can be an asynchronous FIFO. The asynchronous FIFO input write clock rate is 8-divided 125MHz, the output read clock rate is 6-divided 166.7MHz, and the asynchronous FIFO depth is designed according to the crystal oscillator deviation. The requirement can be met, and the ADC data sampling rate can be restored by controlling the asynchronous FIFO read enable according to the crystal oscillator deviation direction and the timing adjustment indication pulse. The timing adjustment indication pulse is obtained by accumulating the integer time indication pulse.

[0063] In step S102, the second level buffer is used to receive data output by the asynchronous FIFO, the first level buffer is used for clock rate adjustment, and the second level buffer is used for rate adjustment between channels. The buffer size is The second level buffer is a data buffer unit. All buffered data are updated synchronously in each clock cycle, and the new data overwrites the old data in turn, and then output to the interpolation filter. The interpolation filter selects different buffered data according to the crystal oscillator offset direction and integer indication pulse.

[0064] In step S103, a local spread spectrum codeword is first generated, and the despread data is obtained by correlating the ADC data after carrier recovery and timing recovery with the locally stored spread spectrum code. Similar to the carrier recovery and timing recovery, the received signal is compensated for carrier frequency, and its input is the carrier frequency deviation. The correlation process can simplify the segmented accumulation of the sampled data, and then the despread data is synchronously captured. The synchronous capture process is a process of searching for correlation peaks. When the preset threshold and the preset number of times are met, the synchronous capture is considered to be successful, and then the code chip synchronization position information is output to the crystal oscillator deviation detector.

[0065] In a specific implementation, loop filtering is performed on the first crystal oscillator deviation value to obtain a second crystal oscillator deviation value, and the second crystal oscillator deviation value is calculated by the following formula:

[0066]

[0067] in, is the second crystal oscillator deviation value after loop filtering of the current symbol, Represents the current symbol filter loop coefficient, It is the crystal oscillator deviation value after loop filtering of the previous symbol.

[0068] The loop filter is a first-order IIR filter. The filter bandwidth is adjusted according to the symbol count. At the beginning, a larger capture bandwidth is used to quickly capture the crystal deviation. As the symbol count increases, the filter bandwidth is slowly reduced to obtain better stability.

[0069] In a specific implementation, the timing error value is calculated by the following formula:

[0070]

[0071] in, Indicates the maximum count integer value, represents the phase conversion factor, Indicates crystal oscillator deviation value, The output range is ,when Changes from one direction to 0 or from the other direction to , Will restart from 0 or Start counting, at this time the interpolation numerically controlled oscillator will output integer time indication pulses to the data buffer unit, and the data buffer unit adjusts the channel data.

[0072] The interpolation numerically controlled oscillator selects the output timing error value to change from small to large or from large to small according to the direction of the crystal oscillator deviation.

[0073] In a specific implementation, the interpolation filtering is calculated by the following formula:

[0074]

[0075] in, The symbol means to take the first value that is smaller than the symbol. The symbol means to take the first value greater than the value inside the symbol. represents the ideal sampling point value, is the previous sampling point of the interpolation filter input. is the next sampling point of the interpolation filter input. The data is restored from the best sampling point.

[0076] Figure 2 FIG. 1 is a schematic diagram of a timing recovery device for UWB according to a preferred embodiment of the present invention. Figure 2 , a timing recovery device for UWB, the device comprising:

[0077] The first level buffer 21 is used to receive high sampling rate multi-channel ADC data and control the time of inserting new multi-channel ADC data through read enable;

[0078] A second level buffer 22, which is used to regularly adjust the rate of the multi-channel ADC data;

[0079] A synchronization module 24, which uses the IQ data after interpolation and carrier recovery to despread the preamble sequence, perform synchronization capture and extract chip synchronization position information;

[0080] A crystal oscillator deviation detector 25, which is used to obtain peak energy information through the code chip synchronization position information and perform crystal oscillator deviation detection;

[0081] A loop filter 26, which is used to dynamically adjust the bandwidth, capture and lock the first crystal oscillator deviation value;

[0082] An interpolation digital controlled oscillator 27, which is used to control a digital controlled oscillator according to the first crystal oscillator deviation value to generate a timing error value and an integer time indication pulse for interpolation;

[0083] An interpolation filter 23, which uses the timing error value and the integer time indication pulse to perform real-time interpolation filtering on the IQ data to restore the ideal data of the best sampling point;

[0084] The first crystal oscillator deviation value is calculated by the following formula:

[0085]

[0086] in, is the first crystal oscillator deviation value, is the update period, arctan is the inverse tangent function, and Respectively in After time despreading Luhe Road data, is the leading symbol period.

[0087] In a specific implementation, the first-level buffer 21 is an asynchronous FIFO (First In First Out), which controls when to insert new multi-channel ADC data through read enable to achieve the purpose of data rate conversion. The second-level buffer 22 is a data buffer unit, which acts as a bridge between the original data and the interpolation filter 23 and adjusts the rate of the multi-channel ADC data regularly.

[0088] In summary, an embodiment of the present invention provides a timing recovery method and device for UWB, the method comprising: receiving high sampling rate multi-channel ADC data, and controlling the time of inserting new multi-channel ADC data through read enable; regularly adjusting the rate of the multi-channel ADC data; using the IQ data after interpolation and carrier recovery to despread the leading sequence, and synchronously capture and extract the code synchronization position information; obtaining the peak energy information through the code synchronization position information, and performing crystal oscillator deviation detection; dynamically adjusting the bandwidth, capturing and locking the first crystal oscillator deviation value; controlling the interpolation digital controlled oscillator according to the first crystal oscillator deviation value, and generating a timing error value and an integer time indication pulse for interpolation; using the timing error value and the integer time indication pulse to perform real-time interpolation filtering on the IQ data, and recovering the ideal data of the best sampling point, which effectively improves the estimation accuracy of the timing error and can converge quickly;

[0089] Furthermore, at high sampling rates, not much storage resources need to be consumed, and the clock frequency is low, which reduces the timing error estimation resources;

[0090] Furthermore, the method significantly improves the receiving sensitivity in demodulation performance.

[0091] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A timing recovery method for UWB, characterized in that: The method comprises: Receive high sampling rate multi-channel ADC data and control the time to insert new multi-channel ADC data through read enable; Regularly adjusting the rate of the multi-channel ADC data; Despread the pilot sequence using the interpolated and carrier-recovered IQ data, perform synchronization capture, and extract the chip synchronization position information; Obtain peak energy information through the chip synchronization position information to perform crystal oscillator deviation detection; Dynamically adjust bandwidth, capture and lock the first crystal oscillator deviation value; Controlling a numerically controlled oscillator according to the first crystal oscillator deviation value to generate a timing error value and an integer time indication pulse for interpolation; Using the timing error value and the integer time indication pulse to perform real-time interpolation filtering on the IQ data to restore the ideal data of the best sampling point; The first crystal oscillator deviation value is calculated by the following formula: in, is the first crystal oscillator deviation value, is the update period, arctan is the inverse tangent function, I(t) and Q(t) are the I-channel and Q-channel data after despreading at time t, respectively. is the leading symbol period; The first crystal oscillator deviation value is loop filtered to obtain a second crystal oscillator deviation value, and the second crystal oscillator deviation value is calculated by the following formula: in, is the second crystal oscillator deviation value after loop filtering of the current symbol, Represents the current symbol filter loop coefficient, is the crystal oscillator deviation value after loop filtering of the previous symbol; The timing error value is calculated by the following formula: Among them, Max represents the maximum count integer value, represents the phase conversion factor, Indicates the crystal oscillator deviation ppm value, The output range is (0, Max). Changes to 0 in one direction or to Max in the other direction, It will start counting again from 0 or Max. At this time, the interpolation numerically controlled oscillator will output integer time indication pulses to the data buffer unit, and the data buffer unit will adjust the channel data.

2. The timing recovery method for UWB according to claim 1, characterized in that: The sampling rate of the multi-channel ADC data is 1 Gsps, and the multi-channel is 8 channels.

3. The timing recovery method for UWB according to claim 1, characterized in that: The ADC data sampling rate is restored according to the crystal oscillator deviation direction and the timing adjustment indication pulse, wherein the timing adjustment indication pulse is obtained by accumulating integer time indication pulses.

4. The timing recovery method for UWB according to claim 1, characterized in that: All cached data are synchronously updated in each clock cycle, and new data sequentially overwrite old data, and then output to the interpolation filter, which selects different cached data according to the crystal oscillator offset direction and the integer indication pulse.

5. The timing recovery method for UWB according to claim 4, characterized in that: The cache data includes a clock rate and a rate between channels.

6. The timing recovery method for UWB according to claim 1, characterized in that: The interpolation filter is calculated by the following formula: in, The symbol means to take the first value that is smaller than the symbol. The symbol indicates taking the first value greater than the symbol upwards, b(m) indicates the ideal sampling point value, is the previous sampling point of the interpolation filter input. is the next sampling point of the interpolation filter input. The data is restored from the best sampling point.

7. A timing recovery device for UWB, characterized in that: The device comprises: The first level buffer is used to receive high sampling rate multi-channel ADC data and control the time of inserting new multi-channel ADC data through read enable; A second level buffer, which is used to regularly adjust the rate of the multi-channel ADC data; A synchronization module, which uses the IQ data after interpolation and carrier recovery to despread the leading sequence, perform synchronization capture and extract the chip synchronization position information; A crystal oscillator deviation detector, which is used to obtain peak energy information through the chip synchronization position information and perform crystal oscillator deviation detection; A loop filter, which is used to dynamically adjust the bandwidth, capture and lock the first crystal oscillator deviation value; An interpolation digitally controlled oscillator, which is used to control a digitally controlled oscillator according to the first crystal oscillator deviation value to generate a timing error value and an integer time indication pulse for interpolation; An interpolation filter, which uses the timing error value and the integer time indication pulse to perform real-time interpolation filtering on the IQ data to restore the ideal data of the best sampling point; The first crystal oscillator deviation value is calculated by the following formula: in, is the first crystal oscillator deviation value, is the update period, arctan is the inverse tangent function, I(t) and Q(t) are the I-channel and Q-channel data after despreading at time t, respectively. is the leading symbol period; The first crystal oscillator deviation value is loop filtered to obtain a second crystal oscillator deviation value, and the second crystal oscillator deviation value is calculated by the following formula: in, is the second crystal oscillator deviation value after loop filtering of the current symbol, Represents the current symbol filter loop coefficient, is the crystal oscillator deviation value after loop filtering of the previous symbol; The timing error value is calculated by the following formula: Among them, Max represents the maximum count integer value, represents the phase conversion factor, Indicates the crystal oscillator deviation ppm value, The output range is (0, Max). Changes to 0 in one direction or to Max in the other direction, It will start counting again from 0 or Max. At this time, the interpolation numerically controlled oscillator will output integer time indication pulses to the data buffer unit, and the data buffer unit will adjust the channel data.

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