CN113132281A - Linear frequency modulation signal tracking method, device, wireless communication equipment and storage medium - Google Patents
Linear frequency modulation signal tracking method, device, wireless communication equipment and storage medium Download PDFInfo
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Abstract
The application relates to a linear frequency modulation signal tracking method, a linear frequency modulation signal tracking device, wireless communication equipment and a storage medium. The method comprises the following steps: acquiring a current linear frequency modulation signal and precompensation information of the current linear frequency modulation signal; pre-compensating the current linear frequency modulation signal according to the pre-compensation information of the current linear frequency modulation signal to obtain a pre-compensated signal; determining a search range of the pre-compensated signal according to a time interval between a current linear frequency modulation signal and a previous linear frequency modulation signal; searching the peak power and the corresponding frequency point of the frequency domain signal in a searching range; and determining the frequency offset and the time offset of the current linear frequency modulation signal according to the frequency point of the peak power. The method ensures that the received linear frequency modulation signal is aligned with the local signal by pre-compensating the received linear frequency modulation signal, searches the peak power and the corresponding frequency point of the frequency domain signal in the search range, reduces the influence of noise, reduces the false alarm rate under the condition of low signal-to-noise ratio, and simultaneously improves the capturing and tracking performance.
Description
Technical Field
The present application relates to the field of wireless communication technologies, and in particular, to a linear frequency modulation signal tracking method and apparatus, a wireless communication device, and a storage medium.
Background
The satellite mobile communication system is a communication system which provides data transmission or communication service for a mobile terminal and a fixed terminal by using a communication satellite, has the advantages of wide coverage, long communication distance, small geographical limitation, capability of providing communication service for the terminal at any time and any place and the like, and is an essential strategic communication system in China.
The Chirp signal is also called as a Chirp signal, has a strong anti-interference characteristic as a large time-bandwidth product signal, and can complete time offset and frequency offset estimation under the condition of a low signal-to-noise ratio, so that the Chirp signal is widely applied to wireless communication systems, particularly high-dynamic communication systems such as satellite communication systems and the like.
In a wireless communication system, due to a Doppler effect caused by relative motion between terminals, the terminals need to track continuously, and the current chirp signal tracking method has a high false alarm rate.
Disclosure of Invention
In view of the above, it is necessary to provide a chirp signal tracking method, apparatus, wireless communication device and storage medium capable of reducing a false alarm rate in response to the above technical problems.
In a first aspect, a chirp tracking method is provided, the method comprising:
acquiring a current linear frequency modulation signal and precompensation information of the current linear frequency modulation signal;
pre-compensating the current linear frequency modulation signal according to the pre-compensation information of the current linear frequency modulation signal to obtain a pre-compensated signal;
determining a search range of the pre-compensated signal according to a time interval between the current chirp signal and a previous chirp signal;
searching the peak power of the frequency domain signal and the corresponding frequency point in the searching range;
and determining the frequency offset and the time offset of the current linear frequency modulation signal according to the frequency point of the peak power.
In one embodiment, the determining of the pre-compensation information of the current chirp signal includes:
and determining the pre-compensation information of the current chirp signal according to the time interval between the current chirp signal and the last chirp signal, the pre-compensation information of the last chirp signal and the frequency offset of the last chirp signal.
In one embodiment, the method further comprises:
when the current chirp signal is the first chirp signal, the frequency offset of the first chirp signal is obtained by sliding capture in the full bandwidth and is used as the pre-compensation information of the next chirp signal.
In one embodiment, the pre-compensation information includes a pre-compensation frequency offset and a pre-compensation time offset;
determining pre-compensation information of the current chirp signal according to a time interval between the current chirp signal and a previous chirp signal, pre-compensation information of the previous chirp signal, and a frequency offset of the previous chirp signal, including:
determining the pre-compensation frequency offset of the current linear frequency modulation signal according to the pre-compensation frequency offset of the previous linear frequency modulation signal and the frequency offset of the previous linear frequency modulation signal;
and determining the pre-compensated time offset of the current linear frequency modulation signal according to the pre-compensated frequency offset of the current linear frequency modulation signal and the time interval.
In one embodiment, determining the pre-compensated time offset of the current chirp signal according to the pre-compensated frequency offset of the current chirp signal and the time interval includes:
and determining the pre-compensation time offset of the current linear frequency modulation signal according to the pre-compensation frequency offset of the current linear frequency modulation signal, the clock precision of the receiving end, the actual sampling rate of the receiving end and the time interval.
In one embodiment, after obtaining the pre-compensated signal, before searching for the peak power of the frequency domain signal and the corresponding frequency point in the search range, the method further includes:
carrying out correlation processing on the precompensated signal and a local signal to obtain a frequency sweeping signal;
and carrying out fast Fourier transform on the sweep frequency signal to obtain a frequency domain signal.
In one embodiment, the search range includes a frequency offset search range and a time offset search range;
determining a search range of the pre-compensated signal according to the time interval, comprising:
determining acceleration frequency deviation and acceleration time deviation according to the time interval and the acceleration of the receiving end;
and determining the search range according to the acceleration frequency offset and the acceleration time offset.
In a second aspect, there is provided a chirp tracking apparatus, the apparatus comprising:
the acquisition module is used for acquiring the current linear frequency modulation signal and precompensation information;
the pre-compensation module is used for pre-compensating the current linear frequency modulation signal according to the pre-compensation information to obtain a pre-compensated signal;
a search range determining module for determining a search range of the pre-compensated signal according to the time interval;
the searching module is used for searching the peak power of the frequency domain signal and the corresponding frequency point in the searching range;
and the determining module is used for determining the frequency offset and the time offset of the current linear frequency modulation signal according to the frequency point of the peak power.
In a third aspect, a wireless communication device is provided, comprising a memory and a processor, the memory storing a computer program, the processor implementing the following steps when executing the computer program:
acquiring a current linear frequency modulation signal and precompensation information of the current linear frequency modulation signal;
pre-compensating the current linear frequency modulation signal according to the pre-compensation information of the current linear frequency modulation signal to obtain a pre-compensated signal;
determining a search range of the pre-compensated signal according to a time interval between the current chirp signal and a previous chirp signal;
searching the peak power of the frequency domain signal and the corresponding frequency point in the searching range;
and determining the frequency offset and the time offset of the current linear frequency modulation signal according to the frequency point of the peak power.
In a fourth aspect, there is provided a computer readable storage medium having stored thereon a computer program which when executed by a processor performs the steps of:
acquiring a current linear frequency modulation signal and precompensation information of the current linear frequency modulation signal;
pre-compensating the current linear frequency modulation signal according to the pre-compensation information of the current linear frequency modulation signal to obtain a pre-compensated signal;
determining a search range of the pre-compensated signal according to a time interval between the current chirp signal and a previous chirp signal;
searching the peak power of the frequency domain signal and the corresponding frequency point in the searching range;
and determining the frequency offset and the time offset of the current linear frequency modulation signal according to the frequency point of the peak power.
The linear frequency modulation signal tracking method, the linear frequency modulation signal tracking device, the wireless communication equipment and the storage medium acquire the current linear frequency modulation signal and the pre-compensation information of the current linear frequency modulation signal; pre-compensating the current linear frequency modulation signal according to the pre-compensation information of the current linear frequency modulation signal to obtain a pre-compensated signal; determining a search range of the pre-compensated signal according to a time interval between the current chirp signal and a previous chirp signal; searching the peak power of the frequency domain signal and the corresponding frequency point in the searching range; and determining the frequency offset and the time offset of the current linear frequency modulation signal according to the frequency point of the peak power. The method ensures that the received linear frequency modulation signal is aligned with the local signal by pre-compensating the received linear frequency modulation signal, and then searches the peak power and the corresponding frequency point of the frequency domain signal in the search range, thereby reducing the influence of noise, reducing the false alarm rate under the condition of low signal-to-noise ratio, and simultaneously improving the capturing and tracking performance.
Drawings
FIG. 1 is a diagram of an exemplary embodiment of a chirp tracking method;
FIG. 2 is a schematic flow chart of a chirp tracking method in one embodiment;
FIG. 3 is a schematic diagram of a waveform of a chirp signal in one embodiment;
FIG. 4 is a functional block diagram of a chirp tracking method in one embodiment;
FIG. 5 is a block diagram of a chirp tracking device in one embodiment;
fig. 6 is an internal block diagram of a wireless communication device in one embodiment.
Detailed Description
In order to make the objects, technical solutions and advantages of the present application more apparent, the present application is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present application and are not intended to limit the present application.
The Chirp signal is also called as a Chirp signal, has a strong anti-interference characteristic as a large time-bandwidth product signal, and can complete time offset and frequency offset estimation under the condition of a low signal-to-noise ratio, so that the Chirp signal is widely applied to wireless communication systems, particularly high-dynamic communication systems such as satellite communication systems and the like.
In a wireless communication system, due to a doppler effect caused by relative motion between terminals and a frequency offset and a sampling offset caused by instability of a terminal clock, the terminals need to continuously track, and therefore, it is significant to complete signal detection, time offset estimation and frequency offset estimation in the wireless communication system.
The Chirp signal is typically transmitted periodically in these systems and can therefore be used as a tracking reference signal for the entire system.
The mathematical expression of the Chirp signal is
Wherein the content of the first and second substances,
t is the duration of the Chirp signal, and the waveform diagram of the Chirp signal is shown in fig. 1.
Any real signal can be represented in the form of the sum of two conjugated complex signals, then:
wherein the content of the first and second substances,
signal of balance component
Is an up-chirp waveform whose instantaneous frequency is derived from time
Is increased to
(ii) a Component signal
Is a down-chirp wave (down-chirp) signal whose instantaneous frequency varies with time
Is reduced to
(ii) a The absolute value of the rate of change of the two component signal frequencies is the same.
The Chirp signal acquisition usually adopts a frequency domain synchronization algorithm and comprises the following steps:
step 1: dividing the received signal into two paths to be compared with the locally pre-stored complex signal
And
multiplying to obtain an up-solution swept frequency signal
Sum-lower solution swept signal
；
Step 2: will be provided with
And
performing FFT operation to obtain frequency domain signal
And
；
and step 3: searching within full bandwidth
And
peak power and corresponding frequency points (if the PAPR is used as the decision criterion, the average power in the whole bandwidth needs to be calculated);
and 4, step 4: if the threshold value is larger than the set threshold value, part of the signals or all the signals are considered to fall into the search window.
When the threshold is assumed to be exceeded, the peak frequency points obtained by the upper and lower frequency sweeping branches are recorded as
And
the equations for calculating the frequency offset and timing offset are as follows:
after the system is synchronized, the Chirp signal still needs to be tracked subsequently.
Considering the doppler effect of the terminal and the influence of the clock precision, there is a certain deviation between the actual arrival time of the Chirp signal in the next period and the ideal time, and the existing methods have two types:
the method comprises the following steps: captured at the desired punctual location. At the moment, timing deviation exists between the received signal and the local signal, the signal falling into a capture window is reduced, the capture gain is reduced, and the false-alarm probability is increased;
the method 2 comprises the following steps: searching according to a certain step. As many signals as possible can be ensured to fall into a capture window, the problem of gain reduction caused by sampling deviation is solved, but as the capture operation needs to be carried out once (Fast Fourier Transform (FFT) operation needs to be carried out twice) every time the signals slide once, the operation amount and the processing time are correspondingly improved; and because the sliding times are more, under the condition of low signal-to-noise ratio, the false alarm probability is increased;
in addition, after the frequency domain is switched to, the power peak position is searched in the whole frequency domain, the range of the peak value is not considered, and under the condition of low signal to noise ratio, the peak power position is wrong due to the fluctuation of noise, so that the false alarm is increased, and the frequency offset and time offset calculation are wrong.
Based on the above, the application provides a linear frequency modulation signal tracking method under the conditions of high dynamic and low signal-to-noise ratio, which can overcome the problem of high false alarm probability or high false alarm probability in the prior art.
The chirp signal tracking method provided by the application can be applied to the application environment shown in fig. 1. Wherein a terminal 102 communicates with another terminal or base station 104 over a wireless network. The terminal 102 acquires the chirp signal received by the receiving end and tracks the signal by using the chirp signal tracking method provided by the application. The terminal 102 may be, but is not limited to, various wireless communication devices such as a personal computer, a notebook computer, a smart phone, a tablet computer, and a vehicle-mounted device.
In one embodiment, as shown in fig. 2, a chirp tracking method is provided, which is described by taking the example that the method is applied to the terminal in fig. 1, and includes the following steps:
The pre-compensation information refers to information for aligning the current chirp signal with the local signal.
Specifically, the terminal 102 serves as a receiving end, another terminal or the base station 104 serves as a transmitting end, the terminal 102 receives the current chirp signal transmitted by the transmitting end, and meanwhile, the terminal acquires pre-compensation information of the current chirp signal from the memory.
And 204, pre-compensating the current linear frequency modulation signal according to the pre-compensation information of the current linear frequency modulation signal to obtain a pre-compensated signal.
Specifically, the frequency offset and the time offset of the current linear frequency modulation signal are precompensated according to precompensation information of the current linear frequency modulation signal, and a precompensated signal is obtained. The pre-compensation can reduce frequency offset and time offset caused by Doppler motion, clock precision and clock precision between the transmitting end and the receiving end, so that the pre-compensated signal is aligned with the local signal.
Specifically, the terminal 102 obtains the time interval of two chirp signals according to the system plan. Carrying out correlation processing on the precompensated signal and a local signal to obtain a frequency domain signal; due to the influences caused by the acceleration of a receiving end and clock drift, the pre-compensated signal cannot be completely aligned with a local signal, the distance change and the speed change between a transmitting end and the receiving end are determined according to the time interval between the current linear frequency modulation signal and the last linear frequency modulation signal and the acceleration of the receiving end, the acceleration time bias can be determined according to the distance change, the acceleration frequency bias can be determined according to the speed change, and the frequency band searching range of the frequency domain signal is determined according to the acceleration frequency bias and the acceleration time bias.
And step 208, searching the peak power of the frequency domain signal and the corresponding frequency point in the searching range.
Specifically, the peak power and the corresponding frequency point of the frequency domain signal are searched in the frequency band searching range. And performing threshold-crossing detection according to the peak power, and if the peak power is greater than a preset threshold value, considering that part of or all of the signals fall into a search window to realize tracking of the signals. The search range of the peak power of the frequency domain signal is limited, the influence of noise is reduced, and the capturing and tracking performance is obviously improved under the condition of low signal-to-noise ratio.
And step 210, determining the frequency offset and the time offset of the current linear frequency modulation signal according to the frequency point of the peak power.
Specifically, if the frequency exceeds the threshold, the peak frequency points obtained by the upper and lower frequency sweeping branches of the frequency domain signal are recorded as
And
the equation for calculating the frequency offset and the time offset of the current chirp signal is as follows:
wherein the content of the first and second substances,
representing the frequency offset of the current chirp signal,
representing the time offset of the current chirp signal.
In the linear frequency modulation signal tracking method, the current linear frequency modulation signal and the pre-compensation information of the current linear frequency modulation signal are obtained; pre-compensating the current linear frequency modulation signal according to the pre-compensation information of the current linear frequency modulation signal to obtain a pre-compensated signal; determining a search range of the pre-compensated signal according to a time interval between the current chirp signal and a previous chirp signal; searching the peak power of the pre-compensated signal within the search range; and determining the frequency offset and the time offset of the current linear frequency modulation signal according to the peak power. The method ensures that the received linear frequency modulation signal is aligned with the local signal by pre-compensating the received linear frequency modulation signal, then searches the peak power of the signal in the searching range, reduces the influence of noise, reduces the false alarm rate under the condition of low signal-to-noise ratio, and simultaneously improves the capturing and tracking performance.
In one embodiment, the determining of the pre-compensation information of the current chirp signal includes:
and determining the pre-compensation information of the current chirp signal according to the time interval between the current chirp signal and the last chirp signal, the pre-compensation information of the last chirp signal and the frequency offset of the last chirp signal.
Specifically, frequency offset accumulation is determined according to the pre-compensation information of the previous linear frequency modulation signal and the frequency offset of the previous linear frequency modulation signal, and the frequency offset accumulation is used as the pre-compensation frequency offset of the current linear frequency modulation signal; and then determining the pre-compensation time offset of the current linear frequency modulation signal according to the pre-compensation frequency offset of the current linear frequency modulation signal and the relation between the frequency offset and the time offset.
In one embodiment, the method further comprises:
when the current chirp signal is the first chirp signal, the frequency offset of the first chirp signal is obtained by sliding capture in the full bandwidth and is used as the pre-compensation information of the next chirp signal.
Specifically, if the received chirp signal is the first chirp signal and the first chirp signal has no wireless frequency offset and cannot be pre-compensated, the frequency offset of the first chirp signal is obtained by sliding capture in a large range and is used as pre-compensation information of the next chirp signal.
In one embodiment, the pre-compensation information includes a pre-compensation frequency offset and a pre-compensation time offset;
determining pre-compensation information of the current chirp signal according to a time interval between the current chirp signal and a previous chirp signal, pre-compensation information of the previous chirp signal, and a frequency offset of the previous chirp signal, including:
determining the pre-compensation frequency offset of the current linear frequency modulation signal according to the pre-compensation frequency offset of the previous linear frequency modulation signal and the frequency offset of the previous linear frequency modulation signal;
and determining the pre-compensated time offset of the current linear frequency modulation signal according to the pre-compensated frequency offset of the current linear frequency modulation signal and the time interval.
Specifically, the pre-compensation frequency offset of the current linear frequency modulation signal is determined according to the pre-compensation frequency offset of the previous linear frequency modulation signal and the frequency offset of the previous linear frequency modulation signal
The specific formula is as follows:
wherein the content of the first and second substances,
representing the pre-compensated frequency offset of the last chirp,
representing the frequency offset of the last chirp.
Determining a relational expression of frequency deviation and time deviation according to the time interval between the current linear frequency modulation signal and the last linear frequency modulation signal and the clock precision of the receiving end, and determining the pre-compensation time deviation of the current linear frequency modulation signal according to the relational expression of the frequency deviation and the time deviation and the pre-compensation frequency deviation of the current linear frequency modulation signal.
In one embodiment, determining the pre-compensated time offset of the current chirp signal based on the pre-compensated frequency offset of the current chirp signal and the time interval comprises:
and determining the pre-compensation time offset of the current linear frequency modulation signal according to the pre-compensation frequency offset of the current linear frequency modulation signal, the clock precision of the receiving end, the actual sampling rate of the receiving end and the time interval.
Specifically, a relational expression of the frequency offset and the time offset is determined according to the time interval between the current linear frequency modulation signal and the last linear frequency modulation signal, the actual sampling rate of the receiving end and the clock precision of the receiving end, and the pre-compensation time offset of the current linear frequency modulation signal is determined according to the relational expression of the frequency offset and the time offset and the pre-compensation frequency offset of the current linear frequency modulation signal.
And calculating the Doppler frequency shift according to the relative motion rule of the transmitting end and the receiving end. Further, assume that the transmit end clock accuracy is
Receiving end clock accuracy of
. The doppler shift caused by the relative motion of the transmitting and receiving ends is:
wherein
The relative speed of the two parties for transmitting and receiving is an unknown parameter,
in order to be the speed of light,
the working frequency band is
。
And calculating the maximum frequency offset according to the deviation caused by the clock accuracy of the transmitting end and the receiving end. The maximum frequency offset is calculated as follows:
wherein the content of the first and second substances,
representing the maximum frequency offset.
Therefore, the pre-compensation frequency offset of the last chirp signal received by the receiving end is:
at the time of maximum speed
Maximum, the sum of the corresponding pre-compensation frequency offsets is maximum, which is:
wherein the content of the first and second substances,
。
the frequency offset of the chirp signal is caused by the relative motion of the transmitting end and the receiving end and the clock accuracy of the systems of the transmitting end and the receiving end, and the reasoning shows that the relative motion and the clock accuracy have the same influence on the Doppler frequency shift, so only one factor is considered in the calculation process.
The effect of doppler motion and clock accuracy on the signal sampling is considered. Taking a spread spectrum signal as an example, the other signals have the same principle. The spreading code signal at the nominal frequency can be expressed as:
wherein
In order to spread the code sequence, it is,
in order to spread the code symbol width,
is a unit rectangular pulse, and the functional expression is as follows:
the ideal sampling rate of the transmitting end is assumed to be
Then the actual sampling rate is
Then, the sampling sequence of the spread spectrum code signal at the transmitting end can be expressed as:
after conversion by a DAC (a converter that converts a discrete signal in the form of a binary digital quantity into an analog quantity based on a standard quantity), the analog signal can be expressed as:
when code doppler is present, the received spread spectrum code signal can be expressed as:
suppose that the receiving end isThe ideal sampling rate is
Then the actual sampling rate is
Thus, the sample sequence of the received signal can be expressed as:
order to
The received signal is equivalent to a use accuracy of
Sampling the desired signal after the clock frequency conversion.
And due to
And when
、
And
when the temperature of the water is higher than the set temperature,
and thus can be ignored, thereby
Error is about
Level, normalized error of
。
Actual conditions
、
And
is much less than
E.g. in general
The clock precision is typically a few ppm (
) And therefore the approximation error is smaller.
Thus, it is possible to prevent the occurrence of,
。
from the above analysis, it can be known that the frequency offset and the time offset are linear relationships, and the time offset can be obtained from the frequency offset:
assuming that the last Chirp signal is correctly captured, the time interval between the current Chirp signal to be captured and the last Chirp signal is
And considering no influence of acceleration and clock stability, the pre-compensation time offset of the current linear frequency modulation signal of the receiving end is as follows:
namely: when the frequency deviation is as
Time of arrival of actual signal lags
Point (or lead)
A point).
Then, when capturing the current Chirp signal, the frequency deviation is precompensated
Time offset precompensation
The sampling points ensure that the received signal is perfectly aligned with the local signal.
In this embodiment, the pre-compensation processing is performed on the chirp signal according to the pre-compensation frequency offset and the pre-compensation time offset of the current chirp signal, the length of the signal falling into the capture window is increased, the capture gain is correspondingly improved, and the capture tracking performance is improved to some extent.
In one embodiment, after obtaining the pre-compensated signal, before searching for the peak power of the frequency domain signal and the corresponding frequency point in the search range, the method further includes:
carrying out correlation processing on the precompensated signal and a local signal to obtain a frequency sweeping signal;
and carrying out fast Fourier transform on the sweep frequency signal to obtain a frequency domain signal.
Specifically, the frequency sweep signal includes an up-solution frequency sweep signal and a down-solution frequency sweep signal. Dividing the pre-compensated signal into two paths to be identical to the locally pre-stored complex signal
And
multiplying to obtain an up-solution swept frequency signal
Sum-lower solution swept signal
。
The frequency domain signal includes an upper and a lower frequency domain signal. Performing FFT operation on the upper solution frequency sweep signal and the lower solution frequency sweep signal to obtain an upper solution frequency domain signal
And the lower solution frequency domain signal
。
Decoding a frequency domain signal over a band search range search
Peak power of
And the lower solution frequency domain signal
Peak power of
. If the PAPR is used as a decision criterion, the average power over the entire bandwidth needs to be calculated. And performing threshold-crossing detection according to the peak power, and if the peak power is greater than a preset threshold value, considering that part of or all of the signals fall into a search window to realize tracking of the signals.
In the embodiment, the influence of noise is reduced by limiting the search range of the peak power of the frequency domain signal, and the capturing and tracking accuracy is obviously improved under the condition of low signal-to-noise ratio. And sliding search is not needed, so that the computation amount and the processing time delay are reduced, and the capturing and tracking efficiency is improved.
In one embodiment, the search range includes a frequency offset search range and a time offset search range;
determining a search range of the pre-compensated signal according to the time interval, comprising:
determining acceleration frequency deviation and acceleration time deviation according to the time interval and the acceleration of the receiving end;
and determining the search range according to the acceleration frequency offset and the acceleration time offset.
Specifically, the acceleration frequency offset and the acceleration time offset are determined according to the time interval and the acceleration of the receiving end; and determining a frequency offset search range and a time offset search range according to the acceleration frequency offset and the acceleration time offset.
In practical situations, due to the influences of acceleration, clock drift and the like, after pre-compensation, the received signal and the local signal cannot be completely aligned, but a reasonable frequency offset and time offset range can be estimated.
Assuming that when the current Chirp signal is captured, the reasonable frequency offset search range and the time offset search range are respectively +/-
And
then there is
,
From the equation of the frequency offset and the time offset of the current chirp signal, it can be known that:
finishing to obtain:
note the book
Then there is
The inequality shows that when the peak power of the frequency domain signal is searched, the searching in the whole frequency band is not needed, and only the searching in the whole frequency band is needed
Searching in the frequency band. Therefore, the influence of the out-of-band noise on the peak position can be greatly reduced under the condition of low signal-to-noise ratio.
Further, if the receiving end has acceleration in the time interval between the current chirp signal and the previous chirp signal, the acceleration in the time interval is set as
The distance between the two parties of communication changes due to acceleration
And speed variation
Respectively as follows:
acceleration time bias caused by acceleration
And acceleration frequency offset
Comprises the following steps:
then
And
can be respectively used as the time offset search range in the capturing process
And frequency offset search range
。
In addition, consider that the maximum frequency offset of the system is
Thereby to make
Further calculation yields:
in conclusion, the frequency offset search range and the time offset search range should be based on the practical application scenario
And
calculated, for simplicity, generally in the order of
。
The above
The minimum range is given in the embodiments of the present application, and the implementation of the present application will properly relax the range according to specific situations or configure the range according to the maximum possible range, and all of the embodiments are within the scope of the present application.
In the embodiment of the application, the acceleration frequency offset and the acceleration time offset are determined by calculating the distance change and the speed change of two communication parties caused by the acceleration of the receiving end, so that the frequency band search range is further accurately determined, and the capture tracking performance is improved.
In order to easily understand the technical solution provided by the embodiment of the present application, as shown in fig. 4, a chirp tracking method provided by the embodiment of the present application is briefly described with a complete chirp tracking process:
(1) and acquiring the current linear frequency modulation signal and the pre-compensation information of the current linear frequency modulation signal.
The pre-compensation information comprises a pre-compensation frequency offset and a pre-compensation time offset;
determining the pre-compensation frequency offset of the current linear frequency modulation signal according to the pre-compensation frequency offset of the previous linear frequency modulation signal and the frequency offset of the previous linear frequency modulation signal;
and determining the pre-compensation time offset of the current linear frequency modulation signal according to the pre-compensation frequency offset of the current linear frequency modulation signal and the time interval.
(2) And pre-compensating the current linear frequency modulation signal according to the pre-compensation information of the current linear frequency modulation signal to obtain a pre-compensated signal.
(3) And determining the search range of the frequency domain signal according to the time interval between the current linear frequency modulation signal and the last linear frequency modulation signal.
(4) Carrying out correlation processing on the precompensated signal and a local signal to obtain a frequency sweeping signal;
performing fast Fourier transform on the frequency sweep signal to obtain a frequency domain signal;
and searching the peak power of the frequency domain signal and the corresponding frequency point in the searching range.
(5) And determining the frequency offset and the time offset of the current linear frequency modulation signal according to the frequency point of the peak power.
It should be understood that, although the steps in the flowcharts of fig. 2 and 4 are shown in sequence as indicated by the arrows, the steps are not necessarily performed in sequence as indicated by the arrows. The steps are not performed in the exact order shown and described, and may be performed in other orders, unless explicitly stated otherwise. Moreover, at least a portion of the steps in fig. 2 and 4 may include multiple steps or multiple stages, which are not necessarily performed at the same time, but may be performed at different times, and the order of performing the steps or stages is not necessarily sequential, but may be performed alternately or alternately with other steps or at least a portion of the steps or stages in other steps.
In one embodiment, as shown in fig. 5, there is provided a chirp tracking apparatus including: an obtaining module 502, a pre-compensation module 504, a search range determining module 506, a search module 508, and a determining module 510, wherein:
the obtaining module 502 is configured to obtain a current chirp signal and pre-compensation information.
The pre-compensation module 504 is configured to pre-compensate the current chirp signal according to the pre-compensation information, so as to obtain a pre-compensated signal.
A search range determining module 506, configured to determine a search range of the pre-compensated signal according to the time interval.
The searching module 508 is configured to search for the peak power of the frequency domain signal and the corresponding frequency point within the search range.
A determining module 510, configured to determine a frequency offset and a time offset of the current chirp signal according to the frequency point of the peak power.
In one embodiment, the chirp tracking apparatus further includes a pre-compensation information determining module for determining pre-compensation information for the current chirp signal based on a time interval between the current chirp signal and a previous chirp signal, pre-compensation information for the previous chirp signal, and a frequency offset of the previous chirp signal.
In one embodiment, the pre-compensation information determining module is further configured to, when the current chirp signal is a first chirp signal, obtain a frequency offset of the first chirp signal by sliding capture within a full bandwidth, and use the frequency offset as the pre-compensation information of a next chirp signal.
In one embodiment, the pre-compensation information includes a pre-compensation frequency offset and a pre-compensation time offset;
the pre-compensation information determining module is further used for determining the pre-compensation frequency offset of the current linear frequency modulation signal according to the pre-compensation frequency offset of the previous linear frequency modulation signal and the frequency offset of the previous linear frequency modulation signal;
and determining the pre-compensated time offset of the current linear frequency modulation signal according to the pre-compensated frequency offset of the current linear frequency modulation signal and the time interval.
In one embodiment, the pre-compensation information determining module is further configured to determine the pre-compensation time offset of the current chirp signal according to the pre-compensation frequency offset of the current chirp signal, the clock accuracy of the receiving end, the actual sampling rate of the receiving end, and the time interval.
In one embodiment, the precompensation module 504 is further configured to perform correlation processing on the precompensated signal and the local signal to obtain a frequency sweep signal;
and carrying out fast Fourier transform on the sweep frequency signal to obtain a frequency domain signal.
In one embodiment, the search range includes a frequency offset search range and a time offset search range;
the search range determining module 506 is further configured to determine an acceleration frequency offset and an acceleration time offset according to the time interval and the acceleration of the receiving end;
and determining the search range according to the acceleration frequency offset and the acceleration time offset.
For specific limitations of the chirp tracking apparatus, reference may be made to the above limitations of the chirp tracking method, which are not described herein again. The various modules in the chirp tracking device described above may be implemented in whole or in part by software, hardware, and combinations thereof. The modules can be embedded in a hardware form or independent from a processor in the wireless communication device, and can also be stored in a memory in the wireless communication device in a software form, so that the processor can call and execute operations corresponding to the modules.
In one embodiment, a wireless communication device is provided, which may be a terminal, and its internal structure diagram may be as shown in fig. 6. The wireless communication device includes a processor, a memory, a communication interface, a display screen, and an input device connected by a system bus. Wherein the processor of the wireless communication device is configured to provide computing and control capabilities. The memory of the wireless communication device includes a non-volatile storage medium, an internal memory. The non-volatile storage medium stores an operating system and a computer program. The internal memory provides an environment for the operation of an operating system and computer programs in the non-volatile storage medium. The communication interface of the wireless communication device is used for carrying out wired or wireless communication with an external terminal, and the wireless communication can be realized through WIFI, an operator network, NFC (near field communication) or other technologies. The computer program is executed by a processor to implement a chirp tracking method. The display screen of the wireless communication equipment can be a liquid crystal display screen or an electronic ink display screen, and the input device of the wireless communication equipment can be a touch layer covered on the display screen, a key, a track ball or a touch pad arranged on the shell of the wireless communication equipment, an external keyboard, a touch pad or a mouse and the like.
Those skilled in the art will appreciate that the architecture shown in fig. 6 is a block diagram of only a portion of the architecture associated with the disclosed aspects and is not intended to limit the wireless communication devices to which the disclosed aspects apply, as a particular wireless communication device may include more or less components than those shown, or may combine certain components, or have a different arrangement of components.
In one embodiment, a wireless communication device is provided, comprising a memory and a processor, the memory having stored therein a computer program, the processor when executing the computer program implementing the steps of:
acquiring a current linear frequency modulation signal and precompensation information of the current linear frequency modulation signal;
pre-compensating the current linear frequency modulation signal according to the pre-compensation information of the current linear frequency modulation signal to obtain a pre-compensated signal;
determining a search range of the pre-compensated signal according to a time interval between the current chirp signal and a previous chirp signal;
searching the peak power of the frequency domain signal and the corresponding frequency point in the searching range;
and determining the frequency offset and the time offset of the current linear frequency modulation signal according to the frequency point of the peak power.
In one embodiment, the processor, when executing the computer program, further performs the steps of: the process of determining the pre-compensation information of the current chirp signal includes: and determining the pre-compensation information of the current chirp signal according to the time interval between the current chirp signal and the last chirp signal, the pre-compensation information of the last chirp signal and the frequency offset of the last chirp signal.
In one embodiment, the processor, when executing the computer program, further performs the steps of: when the current chirp signal is the first chirp signal, the frequency offset of the first chirp signal is obtained by sliding capture in the full bandwidth and is used as the pre-compensation information of the next chirp signal.
In one embodiment, the processor, when executing the computer program, further performs the steps of: the pre-compensation information comprises a pre-compensation frequency offset and a pre-compensation time offset; determining pre-compensation information of the current chirp signal according to a time interval between the current chirp signal and a previous chirp signal, pre-compensation information of the previous chirp signal, and a frequency offset of the previous chirp signal, including: determining the pre-compensation frequency offset of the current linear frequency modulation signal according to the pre-compensation frequency offset of the previous linear frequency modulation signal and the frequency offset of the previous linear frequency modulation signal; and determining the pre-compensated time offset of the current linear frequency modulation signal according to the pre-compensated frequency offset of the current linear frequency modulation signal and the time interval.
In one embodiment, the processor, when executing the computer program, further performs the steps of: determining a pre-compensated time offset of the current chirp signal based on the pre-compensated frequency offset of the current chirp signal and the time interval, including: and determining the pre-compensation time offset of the current linear frequency modulation signal according to the pre-compensation frequency offset of the current linear frequency modulation signal, the clock precision of the receiving end, the actual sampling rate of the receiving end and the time interval.
In one embodiment, the processor, when executing the computer program, further performs the steps of: after the pre-compensated signal is obtained, before searching the peak power of the frequency domain signal and the corresponding frequency point in the search range, the method further comprises the following steps: carrying out correlation processing on the precompensated signal and a local signal to obtain a frequency sweeping signal; and carrying out fast Fourier transform on the sweep frequency signal to obtain a frequency domain signal.
In one embodiment, the processor, when executing the computer program, further performs the steps of: the search range comprises a frequency offset search range and a time offset search range; determining a search range of the pre-compensated signal according to the time interval, comprising: determining acceleration frequency deviation and acceleration time deviation according to the time interval and the acceleration of the receiving end; and determining the search range according to the acceleration frequency offset and the acceleration time offset.
In one embodiment, a computer-readable storage medium is provided, having a computer program stored thereon, which when executed by a processor, performs the steps of:
acquiring a current linear frequency modulation signal and precompensation information of the current linear frequency modulation signal;
pre-compensating the current linear frequency modulation signal according to the pre-compensation information of the current linear frequency modulation signal to obtain a pre-compensated signal;
determining a search range of the pre-compensated signal according to a time interval between the current chirp signal and a previous chirp signal;
searching the peak power of the frequency domain signal and the corresponding frequency point in the searching range;
and determining the frequency offset and the time offset of the current linear frequency modulation signal according to the frequency point of the peak power.
In one embodiment, the computer program when executed by the processor further performs the steps of: the process of determining the pre-compensation information of the current chirp signal includes: and determining the pre-compensation information of the current chirp signal according to the time interval between the current chirp signal and the last chirp signal, the pre-compensation information of the last chirp signal and the frequency offset of the last chirp signal.
In one embodiment, the computer program when executed by the processor further performs the steps of: when the current chirp signal is the first chirp signal, the frequency offset of the first chirp signal is obtained by sliding capture in the full bandwidth and is used as the pre-compensation information of the next chirp signal.
In one embodiment, the computer program when executed by the processor further performs the steps of: the pre-compensation information comprises a pre-compensation frequency offset and a pre-compensation time offset; determining pre-compensation information of the current chirp signal according to a time interval between the current chirp signal and a previous chirp signal, pre-compensation information of the previous chirp signal, and a frequency offset of the previous chirp signal, including: determining the pre-compensation frequency offset of the current linear frequency modulation signal according to the pre-compensation frequency offset of the previous linear frequency modulation signal and the frequency offset of the previous linear frequency modulation signal; and determining the pre-compensated time offset of the current linear frequency modulation signal according to the pre-compensated frequency offset of the current linear frequency modulation signal and the time interval.
In one embodiment, the computer program when executed by the processor further performs the steps of: determining a pre-compensated time offset of the current chirp signal based on the pre-compensated frequency offset of the current chirp signal and the time interval, including: and determining the pre-compensation time offset of the current linear frequency modulation signal according to the pre-compensation frequency offset of the current linear frequency modulation signal, the clock precision of the receiving end, the actual sampling rate of the receiving end and the time interval.
In one embodiment, the computer program when executed by the processor further performs the steps of: after the pre-compensated signal is obtained, before searching the peak power of the frequency domain signal and the corresponding frequency point in the search range, the method further comprises the following steps: carrying out correlation processing on the precompensated signal and a local signal to obtain a frequency sweeping signal; and carrying out fast Fourier transform on the sweep frequency signal to obtain a frequency domain signal.
In one embodiment, the computer program when executed by the processor further performs the steps of: the search range comprises a frequency offset search range and a time offset search range; determining a search range of the pre-compensated signal according to the time interval, comprising: determining acceleration frequency deviation and acceleration time deviation according to the time interval and the acceleration of the receiving end; and determining the search range according to the acceleration frequency offset and the acceleration time offset.
It will be understood by those skilled in the art that all or part of the processes of the methods of the embodiments described above can be implemented by hardware instructions of a computer program, which can be stored in a non-volatile computer-readable storage medium, and when executed, can include the processes of the embodiments of the methods described above. Any reference to memory, storage, database or other medium used in the embodiments provided herein can include at least one of non-volatile and volatile memory. Non-volatile Memory may include Read-Only Memory (ROM), magnetic tape, floppy disk, flash Memory, optical storage, or the like. Volatile Memory can include Random Access Memory (RAM) or external cache Memory. By way of illustration and not limitation, RAM can take many forms, such as Static Random Access Memory (SRAM) or Dynamic Random Access Memory (DRAM), among others.
The technical features of the above embodiments can be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the above embodiments are not described, but should be considered as the scope of the present specification as long as there is no contradiction between the combinations of the technical features.
The above-mentioned embodiments only express several embodiments of the present application, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the concept of the present application, which falls within the scope of protection of the present application. Therefore, the protection scope of the present patent shall be subject to the appended claims.
Claims (10)
1. A method for chirp tracking, the method comprising:
acquiring a current linear frequency modulation signal and precompensation information of the current linear frequency modulation signal;
pre-compensating the current linear frequency modulation signal according to the pre-compensation information of the current linear frequency modulation signal to obtain a pre-compensated signal;
determining a search range of the pre-compensated signal according to a time interval between the current chirp signal and a previous chirp signal;
searching the peak power of the frequency domain signal and the corresponding frequency point in the searching range;
and determining the frequency offset and the time offset of the current linear frequency modulation signal according to the frequency point of the peak power.
2. The method of claim 1, wherein the determining the pre-compensation information of the current chirp signal comprises:
and determining the pre-compensation information of the current linear frequency modulation signal according to the time interval between the current linear frequency modulation signal and the previous linear frequency modulation signal, the pre-compensation information of the previous linear frequency modulation signal and the frequency offset of the previous linear frequency modulation signal.
3. The method of claim 2, further comprising:
and when the current linear frequency modulation signal is the first linear frequency modulation signal, acquiring the frequency offset of the first linear frequency modulation signal by sliding and capturing in the full bandwidth to be used as the pre-compensation information of the next linear frequency modulation signal.
4. The method of claim 2, wherein the pre-compensation information comprises a pre-compensated frequency offset and a pre-compensated time offset;
the determining the pre-compensation information of the current chirp signal according to the time interval between the current chirp signal and the previous chirp signal, the pre-compensation information of the previous chirp signal, and the frequency offset of the previous chirp signal includes:
determining the pre-compensation frequency offset of the current linear frequency modulation signal according to the pre-compensation frequency offset of the previous linear frequency modulation signal and the frequency offset of the previous linear frequency modulation signal;
and determining the pre-compensation time offset of the current linear frequency modulation signal according to the pre-compensation frequency offset of the current linear frequency modulation signal and the time interval.
5. The method of claim 4, wherein determining the pre-compensated time offset of the current chirp signal based on the pre-compensated frequency offset of the current chirp signal and the time interval comprises:
and determining the pre-compensation time offset of the current linear frequency modulation signal according to the pre-compensation frequency offset of the current linear frequency modulation signal, the clock precision of a receiving end, the actual sampling rate of the receiving end and the time interval.
6. The method of claim 1, wherein after obtaining the pre-compensated signal, before searching for the peak power of the frequency domain signal and the corresponding frequency point in the search range, the method further comprises:
carrying out correlation processing on the precompensated signal and a local signal to obtain a frequency sweeping signal;
and carrying out fast Fourier transform on the frequency sweep signal to obtain a frequency domain signal.
7. The method of claim 1, wherein the search range comprises a frequency offset search range and a time offset search range;
the determining a search range of the pre-compensated signal according to the time interval includes:
determining acceleration frequency deviation and acceleration time deviation according to the time interval and the acceleration of the receiving end;
and determining the search range according to the acceleration frequency offset and the acceleration time offset.
8. A chirp tracking apparatus, comprising:
the acquisition module is used for acquiring the current linear frequency modulation signal and precompensation information;
the pre-compensation module is used for pre-compensating the current linear frequency modulation signal according to the pre-compensation information to obtain a pre-compensated signal;
a search range determining module, configured to determine a search range of the pre-compensated signal according to the time interval;
the searching module is used for searching the peak power of the frequency domain signal and the corresponding frequency point in the searching range;
and the determining module is used for determining the frequency offset and the time offset of the current linear frequency modulation signal according to the frequency point of the peak power.
9. A wireless communication device comprising a memory and a processor, the memory storing a computer program, characterized in that the processor, when executing the computer program, implements the steps of the method of any of claims 1 to 7.
10. A computer-readable storage medium, on which a computer program is stored, which, when being executed by a processor, carries out the steps of the method of any one of claims 1 to 7.
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