CN115174323B - Frequency modulation signal detection method, frequency modulation signal detection device, electronic equipment and storage medium - Google Patents
Frequency modulation signal detection method, frequency modulation signal detection device, electronic equipment and storage medium Download PDFInfo
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- H—ELECTRICITY
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- H04L27/00—Modulated-carrier systems
- H04L27/0014—Carrier regulation
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- H—ELECTRICITY
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- H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
- H04B1/69—Spread spectrum techniques
- H04B2001/6912—Spread spectrum techniques using chirp
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- H—ELECTRICITY
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Abstract
The present disclosure provides a method, an apparatus, an electronic device, and a storage medium for detecting a frequency-modulated signal, where the frequency-modulated signal includes a signal frame header and a signal frame body, the signal frame header includes a first specified number of frequency-up signals and a second specified number of frequency-down signals, and the signal frame body includes a third specified number of turn-back frequency-up signals for carrying a third specified number of modulation data, the method includes: determining a starting position of the signal frame head according to the received first specified number of frequency rising signals; calculating carrier frequency offset according to the received first specified number of frequency rising signals and the received second specified number of frequency falling signals; carrying out carrier frequency offset compensation on the received signal frame according to the carrier frequency offset to obtain a compensated signal frame; and demodulating the compensated signal frame body to obtain the modulation data, thereby being convenient for realizing the detection and demodulation of the frequency modulation signal with low cost and low complexity.
Description
Technical Field
The disclosure relates to the field of communication, and in particular relates to a frequency modulation signal detection method, a frequency modulation signal detection device, electronic equipment and a storage medium.
Background
The Chirp signal is a kind of Chirp signal, and the amplitude has no modulation data. In the current technical scheme, the receiver processes amplitude data and phase data simultaneously, and certain invalid operation exists. For example, vector multiplication and fast fourier transform (Fast Fourier Transform, FFT) operations are required, the operation amount is large, and cost and power consumption are not easy to reduce; whereas demodulation is relatively complex with an analog voltage controlled oscillator (Voltage Control Oscillator, VCO).
Disclosure of Invention
In order to solve the problems in the related art, embodiments of the present disclosure provide a method, an apparatus, an electronic device, and a storage medium for detecting a frequency modulation signal.
In a first aspect, an embodiment of the present disclosure provides a method for detecting a fm signal, where the fm signal includes a signal frame header and a signal frame body, the signal frame header includes a first specified number of frequency-up signals and a second specified number of frequency-down signals, and the signal frame body includes a third specified number of return frequency-up signals, where the third specified number of modulation data is carried, the method includes: determining a starting position of the signal frame head according to the received first specified number of frequency rising signals; calculating carrier frequency offset according to the received first specified number of frequency rising signals and the received second specified number of frequency falling signals; carrying out carrier frequency offset compensation on the received signal frame according to the carrier frequency offset to obtain a compensated signal frame; demodulating the compensated signal frame body to obtain the modulation data.
According to an embodiment of the present disclosure, among others,
the first specified number is 10; and/or
The second specified number is 2.
According to an embodiment of the present disclosure, among others,
the initial frequency of the foldback frequency up signal is proportional to the modulation data.
According to an embodiment of the present disclosure, among others,
the frequency range of the FM signal is from a carrier frequency minus 125 kilohertz to a carrier frequency plus 125 kilohertz.
According to an embodiment of the present disclosure, among others,
the determining the start position of the signal frame header according to the received first specified number of frequency rising signals includes:
calculating the frequency of the received frequency-modulated signal according to the I path part and the Q path part of the received frequency-modulated signal, and obtaining the frequency of a received frequency rising signal from the frequency of the received frequency-modulated signal;
dividing a received third appointed number of frequency rising signals into a first part and a second part, calculating a mean value of a first frequency difference according to the frequency of the received first part and the frequency of a first part of pre-stored frequency rising signals, and calculating a mean value of a second frequency difference according to the frequency of the received second part and the frequency of a second part of pre-stored frequency rising signals, wherein the third appointed number is smaller than or equal to the first appointed number;
Calculating a third specified number of frequency difference minimum values according to the average value of the first frequency difference and the average value of the second frequency difference;
calculating the minimum frequency difference vector of the frequency rising signal and the minimum frequency difference vector average value of the frequency rising signal according to the minimum frequency difference value of the third specified number;
and determining the signal frame header according to the minimum frequency difference vector of the frequency rising signal, the minimum frequency difference vector average value of the frequency rising signal and the specified threshold.
According to an embodiment of the present disclosure, among others,
calculating the carrier frequency offset according to the received first specified number of frequency rising signals and the received second specified number of frequency falling signals comprises:
calculating fractional carrier frequency offset according to the minimum frequency difference vector average value of the frequency rising signal and the downward integer value of the minimum frequency difference vector average value of the frequency rising signal;
calculating integer carrier frequency offset according to the minimum frequency difference vector average value of the frequency rising signal and the minimum frequency difference vector average value of the frequency falling signal;
and calculating the carrier frequency offset according to the fractional carrier frequency offset and the integer carrier frequency offset.
According to an embodiment of the present disclosure, among others,
the demodulating the compensated signal frame body to obtain the modulation data includes:
Calculating a frequency difference, a maximum frequency difference and a maximum frequency difference index according to the received foldback frequency rising signal and a pre-stored frequency rising signal;
calculating demodulation data according to the frequency difference, the maximum frequency difference index and the sampling frequency;
and rounding the demodulation data to obtain the modulation data.
According to an embodiment of the present disclosure, among others,
the sampling frequency is obtained by multiplying the symbol rate of the frequency modulated signal by the number of over-samples.
According to an embodiment of the present disclosure, among others,
calculating demodulation data according to the frequency difference, the maximum frequency difference index and the sampling frequency comprises:
calculating demodulation data according to a first partial frequency difference of the foldback frequency rising signal and the sampling frequency under the condition that the maximum frequency difference index is equal to or more than half of the length of the foldback frequency rising signal; and/or
And calculating demodulation data according to the second part frequency difference of the foldback frequency rising signal and the sampling frequency under the condition that the maximum frequency difference index is smaller than half of the length of the foldback frequency rising signal.
According to an embodiment of the present disclosure, among others,
the first partial frequency difference of the foldback frequency up signal includes: a frequency difference between a first portion of the foldback frequency rise signal and a first portion of the frequency rise signal; and/or
The second partial frequency difference of the foldback frequency rising signal includes: a frequency difference between the second portion of the foldback frequency rising signal and the second portion of the frequency rising signal.
In a second aspect, in an embodiment of the present disclosure, there is provided a detection apparatus for a frequency-modulated signal, including:
a signal frame head determining module, configured to determine a start position of the signal frame head according to the received first specified number of frequency rising signals;
the carrier frequency offset calculation module is used for calculating carrier frequency offset according to the received first specified number of frequency rising signals and the received second specified number of frequency falling signals;
the carrier frequency offset compensation module is used for carrying out carrier frequency offset compensation on the received signal frame body according to the carrier frequency offset to obtain a compensated signal frame body;
and the demodulation module is used for demodulating the compensated signal frame body to obtain the modulation data.
In a third aspect, embodiments of the present disclosure provide a chip comprising a detection device for a frequency modulated signal according to the second aspect.
In a fourth aspect, embodiments of the present disclosure provide an electronic device comprising a memory and a processor, wherein the memory is configured to store one or more computer instructions, wherein the one or more computer instructions are executed by the processor to implement the method of the first aspect.
In a fifth aspect, embodiments of the present disclosure provide a computer-readable storage medium having stored thereon computer instructions which, when executed by a processor, implement a method according to the first aspect.
The technical scheme provided by the embodiment of the disclosure can comprise the following beneficial effects:
according to the technical scheme provided by the embodiment of the disclosure, the starting position of the signal frame head is determined according to the received first specified number of frequency rising signals, the carrier frequency offset is calculated according to the received first specified number of frequency rising signals and the received second specified number of frequency falling signals, the carrier frequency offset compensation is carried out on the received signal frame body according to the carrier frequency offset, the compensated signal frame body is obtained, the compensated signal frame body is demodulated, the modulation data is obtained, and the detection and demodulation of the frequency modulation signals are realized with low cost and low complexity.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the disclosure.
Drawings
Other features, objects and advantages of the present disclosure will become more apparent from the following detailed description of non-limiting embodiments, taken in conjunction with the accompanying drawings. In the drawings:
Fig. 1 shows an exemplary schematic diagram of a frequency modulated signal according to an embodiment of the present disclosure.
Fig. 2 shows a flowchart of a method of fm signal detection according to an embodiment of the disclosure.
Fig. 3 shows a flowchart of a signal frame header detection method according to an embodiment of the present disclosure.
Fig. 4 shows a flowchart of a carrier frequency offset calculation method according to an embodiment of the present disclosure.
Fig. 5 shows a flowchart of a demodulation method according to an embodiment of the present disclosure.
Fig. 6 shows a block diagram of a frequency modulated signal detection apparatus according to an embodiment of the present disclosure.
Fig. 7 shows a block diagram of an electronic device according to an embodiment of the disclosure.
Fig. 8 shows a schematic diagram of a computer system suitable for use in implementing methods according to embodiments of the present disclosure.
Detailed Description
Hereinafter, exemplary embodiments of the present disclosure will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily implement them. In addition, for the sake of clarity, portions irrelevant to description of the exemplary embodiments are omitted in the drawings.
In this disclosure, it is to be understood that terms such as "comprises" or "comprising," etc., are intended to indicate the presence of a tag, number, step, action, component, section or combination thereof disclosed in this specification, and are not intended to exclude the possibility that one or more other tags, numbers, steps, actions, components, sections or combinations thereof are present or added.
In addition, it should be noted that, without conflict, the embodiments of the present disclosure and the labels in the embodiments may be combined with each other. The present disclosure will be described in detail below with reference to the accompanying drawings in conjunction with embodiments.
The Chirp signal is a kind of Chirp signal, and has no modulation data in amplitude. In the current technical scheme, the receiver processes amplitude data and phase data simultaneously, and certain invalid operation exists. For example, vector multiplication and fast fourier transform (Fast Fourier Transform, FFT) operations are required, the operation amount is large, and cost and power consumption are not easy to reduce; whereas demodulation is relatively complex with an analog voltage controlled oscillator (Voltage Control Oscillator, VCO).
In order to solve the above problems, the present disclosure provides a method, an apparatus, an electronic device, and a storage medium for detecting a frequency modulated signal.
Fig. 1 shows an exemplary schematic diagram of a frequency modulated signal according to an embodiment of the present disclosure.
Those of ordinary skill in the art will appreciate that fig. 1 illustrates a 1-frame fm signal, and is not limiting of the present disclosure.
As shown in fig. 1, the 1-frame fm signal includes: a frequency rising signal segment, a frequency falling signal segment and a signal frame body.
The frequency rising signal section includes: the frequency up signal, for example, a first specified number of 10 cycles, the frequency down signal segment includes: for example 2, a second specified number of cycles. The signal frame body includes: for example, a third specified number N of cycles of the foldback frequency up signal. The frequency up signal segment and the frequency down signal segment form a signal frame header.
In the disclosed embodiments, the frequency of the frequency up signal increases linearly with time, e.g., from "carrier frequency-125 KHz" to "carrier frequency +125KHz".
In the disclosed embodiments, the frequency up signal may be expressed as:
css_basic_signal_up(m)＝exp(j*2*pi*((m^2/2/M/L^2)-(1/2*m/L)))
wherein L is an oversampling number, which may be an integer not less than 4, SF is a spreading factor, m=2 SF M=0 to L M-1, the step is 1, M2 is the square of M, and L2 is the square of L.
The frequency of the frequency-reduced signal is linearly reduced over time, for example from "carrier frequency +125KHz" to "carrier frequency-125 KHz".
In the disclosed embodiments, the frequency down signal may be expressed as:
css_basic_signal_down(m)＝exp(-j*2*pi*((m^2/2/M/L^2)-(1/2*m/L)))
wherein L is an oversampling number, which may be an integer not less than 4, SF is a spreading factor, m=2 SF M=0 to L M-1, the step is 1, M2 is the square of M, and L2 is the square of L.
The sampling frequency is obtained by multiplying the symbol rate of the frequency modulated signal by the oversampling number L.
In the disclosed embodiment, the initial frequency of the N-period foldback frequency rising signal is proportional to the modulated data D1, D2, &.& gt, DN, respectively, for carrying the modulated data D1, D2, &.& gt, DN-1, DN. In the return frequency rising signal, the frequency is linearly raised from the initial frequency to the carrier frequency +125KHz, and then returned to the carrier frequency-125 KHz, and is linearly raised to the initial frequency.
In the embodiment of the disclosure, for a given symbol modulation value N, 0.ltoreq.N.ltoreq.M-1, the digital foldback frequency up signal expression in one period is:
css_basic_signal_reverse(m)＝exp(j*2*pi*((m^2/2/M/L^2)-(1/2*m/L)))
m＝[L*N:1:L*M-1,0:1:L*N-1]。
in the disclosed embodiment, N is a modulated data value that needs to be transmitted. N may be, for example, 7, or 14.
Those of ordinary skill in the art will appreciate that the first, second, and third specified amounts may be other values, and the disclosure is not limited in this regard.
In the embodiment of the disclosure, at the receiver side, the starting position of the signal frame header may be determined by the received frequency rising signal segment, and then the carrier frequency offset may be calculated according to the received frequency rising signal segment and the frequency falling signal segment. And carrying out carrier frequency offset compensation on the received signal frame body by using the carrier frequency offset to obtain a compensated signal frame body. The signal frame body is demodulated to obtain modulated data D1, D2, and.
In the embodiment of the disclosure, through the design of the frequency rising signal section, the frequency falling signal section and the signal frame body, complex computation such as vector multiplication, FFT and the like can be avoided in the processes of signal frame head detection, carrier frequency offset estimation and demodulation, so that the design is simplified, and the implementation complexity of a receiver is reduced.
In the embodiment of the present disclosure, determining the start position of the signal frame header through the received frequency rising signal segment may be achieved in the following manner.
In the embodiment of the disclosure, through the I-path and Q-path data of the received frequency modulation signal, the inverse tangent atan (Q/I) is obtained to obtain the phase information of the received frequency modulation signal, and the phase information is subjected to front-back difference to obtain the frequency information, which is denoted by y, namely the frequency of the frequency modulation signal. And detecting a frequency rising signal segment according to the frequency rising characteristic in the frequency y of the frequency modulation signal.
The nth frequency up signal yn in the frequency up signal segment is represented as a vector yn= [ yn1, yn2], where yn1 is a first portion of yn and yn2 is a second portion of yn, and lengths of yn1 and yn2 may be the same. The pre-stored frequency up signal up chirp can be expressed as: x= [ x1, x2], x1 is a first part of x, x2 is a second part of x, and x1 and x2 are the same length.
Vector subtraction is performed and then the result of the subtraction is averaged:
Delta_disn1＝mean(yn1-x1)，
Delta_disn2＝mean(yn2-x2)，
mean () is an averaging operation.
The minimum is taken for the two averages of the nth symbol:
Min_dis1＝min(Delta_disn1,Delta_disn2)
taking the latest continuous m (m < N) Min_dis1 values to form a vector
dis_vect＝[Min_dis1(n-m+1),Min_dis1(n-m+2),…Min_dis1(n)]
Continuously sliding a window containing m Min_disco1, and averaging the vectors dis_vect to obtain
Mean_dis2_up＝mean(dis_vect)
Setting a threshold Th determined by simulation, and if max (abs (dis_vect-mean_disco2_up)) < Th, detecting a signal frame header; otherwise, no signal frame header is detected. Where max () is calculated with a maximum value and abs () is calculated with an absolute value.
In the embodiment of the disclosure, after the signal frame header is accurately detected, a frequency-reduced signal segment and a signal frame body can be obtained from the frequency-modulated signal according to the structure of the frequency-modulated signal.
In the disclosed embodiments, after the signal frame header is detected, the fractional carrier frequency offset cfo_frac and the integer carrier frequency offset cfo_int may be estimated.
CFO_frac＝Mean_dis2_up-floor(Mean_dis2_up)
floor () represents a rounding down operation.
In the embodiment of the present disclosure, for the frequency-falling signal segment, another mean_dist2 value, denoted mean_dist2_down, may be calculated by adopting the same processing manner as that of the frequency-rising signal segment, and the mean_dist2_down value is denoted as the integer carrier frequency offset
CFO_int＝round((Mean_dis_up+Mean_dis_down)/2)
round () represents a rounding up operation.
In embodiments of the present disclosure, the total carrier frequency offset
CFO＝CFO_frac+CFO_int
In the embodiment of the disclosure, carrier frequency offset compensation is performed on the received signal frame body through the CFO, so as to obtain a compensated signal frame body, and then the compensated signal frame body is demodulated, so as to obtain modulation data.
For the received foldback frequency rising signal zn after carrier frequency offset compensation, calculating
[Max_val,max_idx]＝max(abs(zn-x))
Wherein max_val is calculated by taking the maximum value, abs () is calculated by taking the absolute value, and the pre-stored frequency rising signal is expressed as: x= [ x1, x2], and max_idx is an index value corresponding to the maximum value.
If max_idx is equal to or greater than M/2, a first partial frequency difference yn1-x1 of the foldback frequency up signal is calculated, and data_demod1=mean (abs (yn 1-x 1)/freq_rate) is calculated,
if max_idx < M/2, the second partial frequency difference yn2-x2 of the foldback frequency up signal is calculated, and data_demod1=mean (abs (yn 2-x 2)/freq_rate) is calculated.
Calculate the demodulated Data data_demod=round (data_demod1)
And changing the value of data_demod into a 2-system value, and performing parallel-serial conversion processing to obtain modulation Data. Where SF is a spreading factor and freq_rate is a rate of change of the frequency of the return frequency rising signal with time.
In the embodiment of the disclosure, in the signal frame header detection, carrier frequency offset estimation and demodulation processes, complex computation such as vector multiplication and FFT is not used, so that the design is simplified, and the implementation complexity of a receiver is reduced.
In an embodiment of the present disclosure, as previously set forth for fig. 1, a 1-frame frequency modulated signal comprises: a frequency rising signal segment, a frequency falling signal segment and a signal frame body.
The frequency rising signal section includes: the frequency up signal, for example, a first specified number of 10 cycles, the frequency down signal segment includes: for example 2, a second specified number of cycles. The signal frame body includes: for example, a third specified number N of cycles of the foldback frequency up signal. The foldback frequency up signal carries the modulated data. The frequency up signal segment and the frequency down signal segment form a signal frame header.
In an embodiment of the present disclosure, the frequency modulated signal includes a signal frame header and a signal frame body.
According to the embodiment of the disclosure, the signal frame header comprises a first specified number of frequency rising signals and a second specified number of frequency falling signals, the signal frame body comprises a third specified number of foldback frequency rising signals and is used for carrying a third specified number of modulation data, and the frequency modulation signals comprise the signal frame header and the signal frame body, so that detection and demodulation of the frequency modulation signals are conveniently realized at low cost and low complexity.
According to an embodiment of the present disclosure, the first specified number is 10; and/or the second designated number is 2, so that frame header detection and carrier frequency offset estimation are conveniently realized.
In the disclosed embodiment, as previously described, the initial frequency of the N-period foldback frequency rising signal is proportional to the modulated data D1, D2, &.& gt, DN for carrying the modulated data D1, D2, &.&... In the return frequency rising signal, the frequency is linearly raised from the initial frequency to the carrier frequency +125KHz, and then returned to the carrier frequency-125 KHz, and is linearly raised to the initial frequency.
According to the embodiment of the disclosure, the initial frequency of the foldback frequency rising signal is in direct proportion to the modulation data, so that the modulation data is conveniently carried in the foldback frequency rising signal.
According to the embodiment of the disclosure, the frequency range of the frequency modulation signal is from 125 kilohertz to 125 kilohertz, so that a good balance is achieved between the bandwidth occupied by the frequency modulation signal and the reliability of detecting the frequency modulation signal.
Fig. 2 shows a flowchart of a method of fm signal detection according to an embodiment of the disclosure.
According to an embodiment of the present disclosure, the frequency modulated signal includes a signal frame header including a first specified number of frequency up signals and a second specified number of frequency down signals, and a signal frame body including a third specified number of return frequency up signals for carrying a third specified number of modulated data.
As shown in fig. 2, the frequency modulation signal detection method includes: steps S201, S202, S203, S204.
In step S201, a start position of the signal frame header is determined according to the received first specified number of frequency up signals.
In step S202, a carrier frequency offset is calculated according to the received first specified number of frequency up signals and the received second specified number of frequency down signals.
In step S203, carrier frequency offset compensation is performed on the received signal frame according to the carrier frequency offset, so as to obtain a compensated signal frame.
In step S204, the compensated signal frame body is demodulated, so as to obtain the modulated data.
According to an embodiment of the present disclosure, determining a start position of the signal frame header by receiving the first specified number of frequency up signals; calculating carrier frequency offset according to the received first specified number of frequency rising signals and the received second specified number of frequency falling signals; carrying out carrier frequency offset compensation on the received signal frame according to the carrier frequency offset to obtain a compensated signal frame; demodulating the compensated signal frame body to obtain the modulation data, so that complex calculations such as vector multiplication, FFT and the like are not used, the design is simplified, the implementation complexity of a receiver is reduced, and the signal frame head synchronization, carrier frequency offset estimation, carrier frequency offset compensation and demodulation are accurately completed to obtain accurate modulation data.
Fig. 3 shows a flowchart of a signal frame header detection method according to an embodiment of the present disclosure.
As shown in fig. 3, the signal frame header detection method includes: steps S301, S302, S303, S304, S305.
In step S301, the frequency of the received variable frequency signal is calculated from the I-path portion and the Q-path portion of the received variable frequency signal, and the frequency of the received frequency-raised signal is obtained from the frequency of the received variable frequency signal.
In step S302, the received third specified number of frequency rising signals is divided into a first part and a second part, a mean value of the first frequency difference is calculated according to the frequency of the received first part and the frequency of the first part of the pre-stored frequency rising signals, and a mean value of the second frequency difference is calculated according to the frequency of the received second part and the frequency of the second part of the pre-stored frequency rising signals, wherein the third specified number is smaller than or equal to the first specified number.
In step S303, a third specified number of frequency difference minima is calculated from the mean value of the first frequency difference and the mean value of the second frequency difference.
In step S304, a minimum frequency difference vector of the frequency rising signal and a minimum frequency difference vector average of the frequency rising signal are calculated according to the third specified number of minimum frequency differences.
In step S305, the signal frame header is determined according to the minimum frequency difference vector of the frequency rising signal, the minimum frequency difference vector average value of the frequency rising signal, and a specified threshold.
In the embodiment of the present disclosure, as described above, in the embodiment of the present disclosure, phase information of a received fm signal is obtained by inverting tangent atan (Q/I) through I-path and Q-path data of the received fm signal, and the phase information is differentiated before and after to obtain frequency information, which is denoted by y, that is, the frequency of the fm signal. And detecting a frequency rising signal segment according to the frequency rising characteristic in the frequency y of the frequency modulation signal.
Setting a threshold Th determined by simulation, and if max (abs (dis_vect-mean_disco2_up)) < Th, detecting a signal frame header; otherwise, no signal frame header is detected. Where max () is calculated with a maximum value and abs () is calculated with an absolute value.
According to an embodiment of the present disclosure, determining the start position of the signal frame header according to the received first specified number of frequency up signals includes: calculating the frequency of the received frequency-modulated signal according to the I path part and the Q path part of the received frequency-modulated signal, and obtaining the frequency of a received frequency rising signal from the frequency of the received frequency-modulated signal; dividing a received third appointed number of frequency rising signals into a first part and a second part, calculating a mean value of a first frequency difference according to the frequency of the received first part and the frequency of a first part of pre-stored frequency rising signals, and calculating a mean value of a second frequency difference according to the frequency of the received second part and the frequency of a second part of pre-stored frequency rising signals, wherein the third appointed number is smaller than or equal to the first appointed number; calculating a third specified number of frequency difference minimum values according to the average value of the first frequency difference and the average value of the second frequency difference; calculating the minimum frequency difference vector of the frequency rising signal and the minimum frequency difference vector average value of the frequency rising signal according to the minimum frequency difference value of the third specified number; and determining the signal frame header according to the minimum frequency difference vector of the frequency rising signal, the minimum frequency difference vector average value of the frequency rising signal and the specified threshold, so that complex calculations such as vector multiplication, FFT and the like are not used, the design is simplified, the implementation complexity of a receiver is reduced, the signal frame header is accurately detected, and the accurate frame synchronization is performed.
Fig. 4 shows a flowchart of a carrier frequency offset calculation method according to an embodiment of the present disclosure.
As shown in fig. 4, the carrier frequency offset calculation method includes: steps S401, S402, S403.
In step S401, a fractional carrier frequency offset is calculated according to the minimum frequency difference vector average value of the frequency rising signal and the downward integer value of the minimum frequency difference vector average value of the frequency rising signal.
In step S402, an integer carrier frequency offset is calculated according to the minimum frequency difference vector average value of the frequency rising signal and the minimum frequency difference vector average value of the frequency falling signal.
In step S403, the carrier frequency offset is calculated according to the fractional carrier frequency offset and the integer carrier frequency offset.
In the embodiment of the disclosure, as described above, after the signal frame header is accurately detected, the frequency-reduced signal segment and the signal frame body may be obtained from the fm signal according to the structure of the fm signal.
In the disclosed embodiments, after the signal frame header is detected, the fractional carrier frequency offset cfo_frac and the integer carrier frequency offset cfo_int may be estimated.
In embodiments of the present disclosure, the total carrier frequency offset
CFO＝CFO_frac+CFO_int。
According to an embodiment of the present disclosure, calculating the carrier frequency offset by receiving the first specified number of frequency up signals and the second specified number of frequency down signals includes: calculating fractional carrier frequency offset according to the minimum frequency difference vector average value of the frequency rising signal and the downward integer value of the minimum frequency difference vector average value of the frequency rising signal; calculating integer carrier frequency offset according to the minimum frequency difference vector average value of the frequency rising signal and the minimum frequency difference vector average value of the frequency falling signal; and calculating the carrier frequency offset according to the fractional carrier frequency offset and the integer carrier frequency offset, so that complex calculations such as vector multiplication, FFT and the like are not used, the design is simplified, the implementation complexity of the receiver is reduced, the carrier frequency offset is accurately calculated, accurate compensation of the carrier frequency offset is facilitated, and modulation data is conveniently and accurately demodulated.
Fig. 5 shows a flowchart of a demodulation method according to an embodiment of the present disclosure.
As shown in fig. 5, the demodulation method includes: steps S501, S502, S503.
In step S501, a frequency difference, a maximum frequency difference, and a maximum frequency difference index are calculated from the received foldback frequency up signal and the pre-stored frequency up signal.
In step S502, demodulation data is calculated from the frequency difference, the maximum frequency difference index, and the sampling frequency.
In step S503, a rounding operation is performed on the demodulated data, so as to obtain the modulated data.
As described above, in the embodiment of the present disclosure, carrier frequency offset compensation is performed on the received signal frame body through CFO, so as to obtain a compensated signal frame body, and then the compensated signal frame body is demodulated, so as to obtain modulated data.
For the received foldback frequency rising signal zn after carrier frequency offset compensation, calculating
[Max_val,max_idx]＝max(abs(zn-x))
Wherein max_val is calculated by taking the maximum value, abs () is calculated by taking the absolute value, and the pre-stored frequency rising signal is expressed as: x= [ x1, x2], and max_idx is an index value corresponding to the maximum value.
If max_idx is equal to or greater than M/2, a first partial frequency difference yn1-x1 of the foldback frequency up signal is calculated, and data_demod1=mean (abs (yn 1-x 1)/freq_rate) is calculated,
If max_idx < M/2, the second partial frequency difference yn2-x2 of the foldback frequency up signal is calculated, and data_demod1=mean (abs (yn 2-x 2)/freq_rate) is calculated.
Calculate the demodulated Data data_demod=round (data_demod1)
And changing the value of data_demod into a 2-system value, and performing parallel-serial conversion processing to obtain modulation Data. Where SF is a spreading factor and freq_rate is a rate of change of the frequency of the return frequency rising signal with time.
According to an embodiment of the present disclosure, the demodulating the compensated signal frame body to obtain the modulated data includes: calculating a frequency difference, a maximum frequency difference and a maximum frequency difference index according to the received foldback frequency rising signal and a pre-stored frequency rising signal; calculating demodulation data according to the frequency difference, the maximum frequency difference index and the sampling frequency; and (3) rounding the demodulation data to obtain the modulation data, so that complex calculations such as vector multiplication, FFT and the like are not used, the design is simplified, the implementation complexity of a receiver is reduced, and the modulation data is accurately demodulated.
According to the embodiment of the disclosure, the sampling frequency is obtained by multiplying the symbol rate of the frequency-modulated signal by the oversampling number, so that the complete information in the received frequency-modulated signal is better obtained by an oversampling mode, and the reliability of detection is improved.
According to an embodiment of the present disclosure, calculating demodulation data by referring to the frequency difference, the maximum frequency difference index, and the sampling frequency includes: calculating demodulation data according to a first partial frequency difference of the foldback frequency rising signal and the sampling frequency under the condition that the maximum frequency difference index is equal to or more than half of the length of the foldback frequency rising signal; and/or under the condition that the maximum frequency difference index is smaller than half of the length of the foldback frequency rising signal, calculating demodulation data according to the second part frequency difference of the foldback frequency rising signal and the sampling frequency, so that complex calculation such as vector multiplication, FFT and the like is not used, the design is simplified, the implementation complexity of a receiver is reduced, and the demodulation data is accurately demodulated.
According to an embodiment of the present disclosure, the frequency difference by the first portion of the foldback frequency rising signal includes: a frequency difference between a first portion of the foldback frequency rise signal and a first portion of the frequency rise signal; and/or the second partial frequency difference of the foldback frequency up signal comprises: the frequency difference between the second portion of the foldback frequency rising signal and the second portion of the frequency rising signal improves the accuracy of demodulation.
According to an embodiment of the present disclosure, a generating device for generating a frequency modulated signal includes: a signal frame header generation module, configured to generate a signal frame header, where the signal frame header includes: a first specified number of frequency up signals; a second specified number of frequency down signals; the signal frame body generating module is used for generating a signal frame body, the signal frame body comprises a third appointed number of foldback frequency rising signals and is used for carrying a third appointed number of modulation data, and the frequency modulation signals comprise the signal frame head and the signal frame body, so that the detection and demodulation of the frequency modulation signals are conveniently realized at low cost and low complexity.
The embodiment of the disclosure also provides a chip, which comprises the frequency modulation signal detection device, wherein the chip can be any chip capable of realizing frequency modulation signal detection, and the device can be realized into part or all of the chip through software, hardware or the combination of the two.
Fig. 6 shows a block diagram of a frequency modulated signal detection apparatus according to an embodiment of the present disclosure.
As shown in fig. 6, the fm signal detection apparatus includes: a signal frame head determining module 601, a carrier frequency offset calculating module 602, a carrier frequency offset compensating module 603 and a demodulating module 604.
A signal frame header determining module 601, configured to determine a start position of the signal frame header according to the received first specified number of frequency rising signals;
a carrier frequency offset calculation module 602, configured to calculate a carrier frequency offset according to the received first specified number of frequency rising signals and the received second specified number of frequency falling signals;
the carrier frequency offset compensation module 603 is configured to perform carrier frequency offset compensation on the received signal frame according to the carrier frequency offset, so as to obtain a compensated signal frame;
and a demodulation module 604, configured to demodulate the compensated signal frame body to obtain the modulated data.
According to the embodiment of the disclosure, a signal frame head determining module is used for determining a starting position of the signal frame head according to the received first specified number of frequency rising signals; the carrier frequency offset calculation module is used for calculating carrier frequency offset according to the received first specified number of frequency rising signals and the received second specified number of frequency falling signals; the carrier frequency offset compensation module is used for carrying out carrier frequency offset compensation on the received signal frame body according to the carrier frequency offset to obtain a compensated signal frame body; the demodulation module is used for demodulating the compensated signal frame body to obtain the modulation data, so that complex calculations such as vector multiplication, FFT and the like are not used, the design is simplified, the implementation complexity of the receiver is reduced, the signal frame head synchronization, carrier frequency offset estimation, carrier frequency offset compensation and demodulation are accurately completed, and the accurate modulation data are obtained.
Fig. 7 shows a block diagram of an electronic device according to an embodiment of the disclosure.
As shown in fig. 7, the electronic device includes a memory and a processor, wherein the memory is configured to store one or more computer instructions, wherein the one or more computer instructions are executed by the processor to implement:
a method of detecting a frequency modulated signal, the frequency modulated signal comprising a signal frame header and a signal frame body, the signal frame header comprising a first specified number of frequency up-signals and a second specified number of frequency down-signals, the signal frame body comprising a third specified number of fold-back frequency up-signals for carrying a third specified number of modulated data, the method comprising: determining a starting position of the signal frame head according to the received first specified number of frequency rising signals; calculating carrier frequency offset according to the received first specified number of frequency rising signals and the received second specified number of frequency falling signals; carrying out carrier frequency offset compensation on the received signal frame according to the carrier frequency offset to obtain a compensated signal frame; demodulating the compensated signal frame body to obtain the modulation data.
In an embodiment of the present disclosure, a method for processing a web,
the first specified number is 10; and/or
The second specified number is 2.
In an embodiment of the present disclosure, a method for processing a web,
the initial frequency of the foldback frequency up signal is proportional to the modulation data.
In an embodiment of the present disclosure, a method for processing a web,
the frequency range of the FM signal is from a carrier frequency minus 125 kilohertz to a carrier frequency plus 125 kilohertz.
In an embodiment of the present disclosure, a method for processing a web,
the determining the start position of the signal frame header according to the received first specified number of frequency rising signals includes:
calculating the frequency of the received frequency-modulated signal according to the I path part and the Q path part of the received frequency-modulated signal, and obtaining the frequency of a received frequency rising signal from the frequency of the received frequency-modulated signal;
dividing a received third appointed number of frequency rising signals into a first part and a second part, calculating a mean value of a first frequency difference according to the frequency of the received first part and the frequency of a first part of pre-stored frequency rising signals, and calculating a mean value of a second frequency difference according to the frequency of the received second part and the frequency of a second part of pre-stored frequency rising signals, wherein the third appointed number is smaller than or equal to the first appointed number;
Calculating a third specified number of frequency difference minimum values according to the average value of the first frequency difference and the average value of the second frequency difference;
calculating the minimum frequency difference vector of the frequency rising signal and the minimum frequency difference vector average value of the frequency rising signal according to the minimum frequency difference value of the third specified number;
and determining the signal frame header according to the minimum frequency difference vector of the frequency rising signal, the minimum frequency difference vector average value of the frequency rising signal and the specified threshold.
In an embodiment of the present disclosure, a method for processing a web,
calculating the carrier frequency offset according to the received first specified number of frequency rising signals and the received second specified number of frequency falling signals comprises:
calculating fractional carrier frequency offset according to the minimum frequency difference vector average value of the frequency rising signal and the downward integer value of the minimum frequency difference vector average value of the frequency rising signal;
calculating integer carrier frequency offset according to the minimum frequency difference vector average value of the frequency rising signal and the minimum frequency difference vector average value of the frequency falling signal;
and calculating the carrier frequency offset according to the fractional carrier frequency offset and the integer carrier frequency offset.
In an embodiment of the present disclosure, a method for processing a web,
the demodulating the compensated signal frame body to obtain the modulation data includes:
Calculating a frequency difference, a maximum frequency difference and a maximum frequency difference index according to the received foldback frequency rising signal and a pre-stored frequency rising signal;
calculating demodulation data according to the frequency difference, the maximum frequency difference index and the sampling frequency;
and rounding the demodulation data to obtain the modulation data.
In an embodiment of the present disclosure, a method for processing a web,
the sampling frequency is obtained by multiplying the symbol rate of the frequency modulated signal by the number of over-samples.
In an embodiment of the present disclosure, a method for processing a web,
calculating demodulation data according to the frequency difference, the maximum frequency difference index and the sampling frequency comprises:
calculating demodulation data according to a first partial frequency difference of the foldback frequency rising signal and the sampling frequency under the condition that the maximum frequency difference index is equal to or more than half of the length of the foldback frequency rising signal; and/or
And calculating demodulation data according to the second part frequency difference of the foldback frequency rising signal and the sampling frequency under the condition that the maximum frequency difference index is smaller than half of the length of the foldback frequency rising signal.
In an embodiment of the present disclosure, a method for processing a web,
the first partial frequency difference of the foldback frequency up signal includes: a frequency difference between a first portion of the foldback frequency rise signal and a first portion of the frequency rise signal; and/or
The second partial frequency difference of the foldback frequency rising signal includes: a frequency difference between the second portion of the foldback frequency rising signal and the second portion of the frequency rising signal.
Fig. 8 shows a schematic diagram of a computer system suitable for use in implementing methods according to embodiments of the present disclosure.
As shown in fig. 8, the computer system includes a processing unit that can execute various processes in the above-described embodiments in accordance with a program stored in a Read Only Memory (ROM) or a program loaded from a storage section into a Random Access Memory (RAM). In the RAM, various programs and data required for the system operation are also stored. The processing unit, ROM and RAM are connected to each other by a bus. An input/output (I/O) interface is also connected to the bus.
The following components are connected to the I/O interface: an input section including a keyboard, a mouse, etc.; an output section including a Cathode Ray Tube (CRT), a Liquid Crystal Display (LCD), etc., and a speaker, etc.; a storage section including a hard disk or the like; and a communication section including a network interface card such as a LAN card, a modem, and the like. The communication section performs communication processing via a network such as the internet. The drives are also connected to the I/O interfaces as needed. Removable media such as magnetic disks, optical disks, magneto-optical disks, semiconductor memories, and the like are mounted on the drive as needed so that a computer program read therefrom is mounted into the storage section as needed. The processing unit may be implemented as a processing unit such as CPU, GPU, TPU, FPGA, NPU.
In particular, according to embodiments of the present disclosure, the methods described above may be implemented as computer software programs. For example, embodiments of the present disclosure include a computer program product comprising computer instructions which, when executed by a processor, implement the method steps described above. In such embodiments, the computer program product may be downloaded and installed from a network via a communications portion, and/or installed from a removable medium.
The flowcharts and block diagrams in the figures illustrate the architecture, functionality, and operation of possible implementations of systems, methods and computer program products according to various embodiments of the present disclosure. In this regard, each block in the flowchart or block diagrams may represent a module, segment, or portion of code, which comprises one or more executable instructions for implementing the specified logical function(s). It should also be noted that, in some alternative implementations, the functions noted in the block may occur out of the order noted in the figures. For example, two blocks shown in succession may, in fact, be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending upon the functionality involved. It will also be noted that each block of the block diagrams and/or flowchart illustration, and combinations of blocks in the block diagrams and/or flowchart illustration, can be implemented by special purpose hardware-based systems which perform the specified functions or acts, or combinations of special purpose hardware and computer instructions.
The units or modules referred to in the embodiments of the present disclosure may be implemented in software or in programmable hardware. The units or modules described may also be provided in a processor, the names of which in some cases do not constitute a limitation of the unit or module itself.
As another aspect, the present disclosure also provides a computer-readable storage medium, which may be a computer-readable storage medium included in the electronic device or the computer system in the above-described embodiments; or may be a computer-readable storage medium, alone, that is not assembled into a device. The computer-readable storage medium stores one or more programs for use by one or more processors in performing the methods described in the present disclosure.
The foregoing description is only of the preferred embodiments of the present disclosure and description of the principles of the technology being employed. It will be appreciated by those skilled in the art that the scope of the invention referred to in this disclosure is not limited to the specific combination of features described above, but encompasses other embodiments in which any combination of features described above or their equivalents is contemplated without departing from the inventive concepts described. Such as those described above, are mutually substituted with the technical features having similar functions disclosed in the present disclosure (but not limited thereto).
Claims (21)
1. A method of detecting a frequency modulated signal, the frequency modulated signal comprising a signal frame header and a signal frame body, the signal frame header comprising a first specified number of frequency up-signals and a second specified number of frequency down-signals, the signal frame body comprising a third specified number of fold-back frequency up-signals for carrying a third specified number of modulated data, the method comprising:
calculating the frequency of the received frequency-modulated signal according to the I path part and the Q path part of the received frequency-modulated signal, and obtaining the frequency of a received frequency rising signal from the frequency of the received frequency-modulated signal;
dividing a received third appointed number of frequency rising signals into a first part and a second part, calculating a mean value of a first frequency difference according to the frequency of the received first part and the frequency of a first part of pre-stored frequency rising signals, and calculating a mean value of a second frequency difference according to the frequency of the received second part and the frequency of a second part of pre-stored frequency rising signals, wherein the third appointed number is smaller than or equal to the first appointed number;
calculating a third specified number of frequency difference minimum values according to the average value of the first frequency difference and the average value of the second frequency difference;
Calculating the minimum frequency difference vector of the frequency rising signal and the minimum frequency difference vector average value of the frequency rising signal according to the minimum frequency difference value of the third specified number;
determining the signal frame header according to the minimum frequency difference vector of the frequency rising signal, the minimum frequency difference vector average value of the frequency rising signal and a specified threshold;
calculating carrier frequency offset according to the received first specified number of frequency rising signals and the received second specified number of frequency falling signals;
carrying out carrier frequency offset compensation on the received signal frame according to the carrier frequency offset to obtain a compensated signal frame;
demodulating the compensated signal frame body to obtain the modulation data.
2. The method of claim 1, wherein the first specified number is 10; and/or said second specified number is 2.
3. The method of claim 1, wherein the step of determining the position of the substrate comprises,
the initial frequency of the foldback frequency up signal is proportional to the modulation data.
4. The method of claim 1, wherein the step of determining the position of the substrate comprises,
the frequency range of the FM signal is from a carrier frequency minus 125 kilohertz to a carrier frequency plus 125 kilohertz.
5. The method of claim 1, wherein the step of determining the position of the substrate comprises,
calculating the carrier frequency offset according to the received first specified number of frequency rising signals and the received second specified number of frequency falling signals comprises:
calculating fractional carrier frequency offset according to the minimum frequency difference vector average value of the frequency rising signal and the downward integer value of the minimum frequency difference vector average value of the frequency rising signal;
calculating integer carrier frequency offset according to the minimum frequency difference vector average value of the frequency rising signal and the minimum frequency difference vector average value of the frequency falling signal;
and calculating the carrier frequency offset according to the fractional carrier frequency offset and the integer carrier frequency offset.
6. The method of claim 4, wherein the step of determining the position of the first electrode is performed,
the demodulating the compensated signal frame body to obtain the modulation data includes:
calculating a frequency difference, a maximum frequency difference and a maximum frequency difference index according to the received foldback frequency rising signal and a pre-stored frequency rising signal;
calculating demodulation data according to the frequency difference, the maximum frequency difference index and the sampling frequency;
and rounding the demodulation data to obtain the modulation data.
7. The method of claim 6, wherein the step of providing the first layer comprises,
The sampling frequency is obtained by multiplying the symbol rate of the frequency modulated signal by the number of over-samples.
8. The method of claim 6, wherein the step of providing the first layer comprises,
calculating demodulation data according to the frequency difference, the maximum frequency difference index and the sampling frequency comprises:
calculating demodulation data according to a first partial frequency difference of the foldback frequency rising signal and the sampling frequency under the condition that the maximum frequency difference index is equal to or more than half of the length of the foldback frequency rising signal; and/or
And calculating demodulation data according to the second part frequency difference of the foldback frequency rising signal and the sampling frequency under the condition that the maximum frequency difference index is smaller than half of the length of the foldback frequency rising signal.
9. The method of claim 8, wherein the step of determining the position of the first electrode is performed,
the first partial frequency difference of the foldback frequency up signal includes: a frequency difference between a first portion of the foldback frequency rise signal and a first portion of the frequency rise signal; and/or
The second partial frequency difference of the foldback frequency rising signal includes: a frequency difference between the second portion of the foldback frequency rising signal and the second portion of the frequency rising signal.
10. A detection apparatus for a frequency modulated signal, the frequency modulated signal comprising a signal frame header and a signal frame body, the signal frame header comprising a first specified number of frequency up-signals and a second specified number of frequency down-signals, the signal frame body comprising a third specified number of fold-back frequency up-signals for carrying a third specified number of modulated data, the apparatus comprising:
the signal frame head determining module is used for calculating the frequency of the received frequency modulation signal according to the I path part and the Q path part of the received frequency modulation signal, and obtaining the frequency of the received frequency rising signal from the frequency of the received frequency modulation signal;
dividing a received third appointed number of frequency rising signals into a first part and a second part, calculating a mean value of a first frequency difference according to the frequency of the received first part and the frequency of a first part of pre-stored frequency rising signals, and calculating a mean value of a second frequency difference according to the frequency of the received second part and the frequency of a second part of pre-stored frequency rising signals, wherein the third appointed number is smaller than or equal to the first appointed number;
calculating a third specified number of frequency difference minimum values according to the average value of the first frequency difference and the average value of the second frequency difference;
Calculating the minimum frequency difference vector of the frequency rising signal and the minimum frequency difference vector average value of the frequency rising signal according to the minimum frequency difference value of the third specified number;
determining the signal frame header according to the minimum frequency difference vector of the frequency rising signal, the minimum frequency difference vector average value of the frequency rising signal and a specified threshold;
the carrier frequency offset calculation module is used for calculating carrier frequency offset according to the received first specified number of frequency rising signals and the received second specified number of frequency falling signals;
the carrier frequency offset compensation module is used for carrying out carrier frequency offset compensation on the received signal frame body according to the carrier frequency offset to obtain a compensated signal frame body;
and the demodulation module is used for demodulating the compensated signal frame body to obtain the modulation data.
11. The apparatus of claim 10, wherein the first specified number is 10; and/or said second specified number is 2.
12. The apparatus of claim 10, wherein the device comprises a plurality of sensors,
the initial frequency of the foldback frequency up signal is proportional to the modulation data.
13. The apparatus of claim 10, wherein the device comprises a plurality of sensors,
the frequency range of the FM signal is from a carrier frequency minus 125 kilohertz to a carrier frequency plus 125 kilohertz.
14. The apparatus of claim 10, wherein the device comprises a plurality of sensors,
the calculating carrier frequency offset according to the received first specified number of frequency rising signals and the received second specified number of frequency falling signals comprises:
calculating fractional carrier frequency offset according to the minimum frequency difference vector average value of the frequency rising signal and the downward integer value of the minimum frequency difference vector average value of the frequency rising signal;
calculating integer carrier frequency offset according to the minimum frequency difference vector average value of the frequency rising signal and the minimum frequency difference vector average value of the frequency falling signal;
and calculating the carrier frequency offset according to the fractional carrier frequency offset and the integer carrier frequency offset.
15. The apparatus of claim 14, wherein the device comprises a plurality of sensors,
the demodulating the compensated signal frame body to obtain the modulation data includes:
calculating a frequency difference, a maximum frequency difference and a maximum frequency difference index according to the received foldback frequency rising signal and a pre-stored frequency rising signal;
calculating demodulation data according to the frequency difference, the maximum frequency difference index and the sampling frequency;
and rounding the demodulation data to obtain the modulation data.
16. The apparatus of claim 15, wherein the device comprises a plurality of sensors,
The sampling frequency is obtained by multiplying the symbol rate of the frequency modulated signal by the number of over-samples.
17. The apparatus of claim 15, wherein the device comprises a plurality of sensors,
calculating demodulation data according to the frequency difference, the maximum frequency difference index and the sampling frequency comprises:
calculating demodulation data according to a first partial frequency difference of the foldback frequency rising signal and the sampling frequency under the condition that the maximum frequency difference index is equal to or more than half of the length of the foldback frequency rising signal; and/or
And calculating demodulation data according to the second part frequency difference of the foldback frequency rising signal and the sampling frequency under the condition that the maximum frequency difference index is smaller than half of the length of the foldback frequency rising signal.
18. The apparatus of claim 17, wherein the device comprises a plurality of sensors,
the first partial frequency difference of the foldback frequency up signal includes: a frequency difference between a first portion of the foldback frequency rise signal and a first portion of the frequency rise signal; and/or
The second partial frequency difference of the foldback frequency rising signal includes: a frequency difference between the second portion of the foldback frequency rising signal and the second portion of the frequency rising signal.
19. A chip comprising a detection device for a frequency modulated signal according to any one of claims 10-18.
20. An electronic device includes a memory and a processor; wherein the memory is for storing one or more computer instructions, wherein the one or more computer instructions are executed by the processor to implement the method steps of any of claims 1-9.
21. A readable storage medium having stored thereon computer instructions which, when executed by a processor, implement the method steps of any of claims 1-9.
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