CN111487476B - Quasi-peak detection method and quasi-peak detector - Google Patents
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Abstract
The application discloses quasi-peak detection method and quasi-peak detector, including A/D conversion module, digital control oscillator, RBW module, module of seeking mould and quasi-peak detection module, firstly wait to examine signal conversion digital signal, again to the digital signal that obtains with quadrature mixing mode mixing to zero frequency signal, filter according to a preset bandwidth to obtaining first mixing signal I and second mixing signal Q respectively, and to first mixing signal I and second mixing signal Q modulus after the filtration in order to obtain the module value sequence, carry out quasi-peak detection to waiting to examine signal according to the module value sequence at last. Because the quasi-peak detection is carried out after the signal to be detected is converted into the digital signal, the digitization of the quasi-peak detector is realized, and the quasi-peak detection is more accurate, quicker and easy to store.
Description
Technical Field
The invention relates to the technical field of electromagnetic interference measurement, in particular to a quasi-peak detection method and a quasi-peak detector.
Background
Electromagnetic interference is composed of useless and spurious conducted and radiated electric signals, all electronic and electric products have the problem of electromagnetic interference, the electromagnetic interference can be instantaneous, pulse or steady in a time domain, and the electromagnetic interference frequency spectrum component is from 50Hz power frequency to microwave signals in a frequency domain. The electromagnetic interference signal may be narrowband or wideband, and may be coherent or non-coherent. In order to reflect the characteristics of the electromagnetic interference signal, the emc test receiver employs various detection methods, such as peak detection, quasi-peak detection, mean square detection (RMS), bias compensation detection, and amplitude probability distribution detection. The GB/T6113/CISPR16 standard specifies the EMI measurement specification, wherein there is an explicit measurement method for peak-detected receivers. The quasi-peak detector in the prior art is realized by adopting an analog circuit formed by analog devices, so that the detection result of the quasi-peak detector is influenced by the performance of the analog devices, the temperature of the working environment and other factors, and the problems of large measurement error, poor stability, difficult parameterization, low flexibility, low measurement speed and the like exist.
Disclosure of Invention
The application discloses a quasi-peak detection method and a quasi-peak detector, which realize digital improvement of the quasi-peak detector in the prior art.
According to a first aspect, there is provided in an embodiment a quasi-peak detection method comprising:
converting the signal to be detected into a digital signal;
mixing the digital signal to a zero-frequency signal in a quadrature mixing mode to obtain a first mixing signal I and a second mixing signal Q;
filtering the first mixing signal I and the second mixing signal Q according to a preset bandwidth respectively;
performing modulo on the filtered first mixing signal I and the filtered second mixing signal Q to obtain a modulus sequence;
and carrying out quasi-peak detection on the signal to be detected according to the modulus sequence.
Further, the mixing the digital signal to a zero-frequency signal in a quadrature mixing manner to obtain a first mixing signal I and a second mixing signal Q, further includes:
the first mixing signal I and the second mixing signal Q are down-sampled before being filtered according to a preset bandwidth.
Further, the preset bandwidth comprises a 6dB bandwidth.
Further, the quasi-peak detection of the signal to be detected according to the modulus sequence includes:
inputting the modulus sequence into a charge and discharge detection model, wherein the charge and discharge detection model formula comprises:
y(n)=b0x(n)+b1x(n-1)-a1y(n-1);
wherein x (n) is the modulus sequence input to the charge-discharge detection wave model, and y (n) is the output sequence of the charge-discharge detection wave model;
when the charge-discharge detection wave model is charged:
b0=b1=(1+2τcha/Ts)-1,a1=(1-2τcha/Ts)/ (1+2τcha/Ts),τchais the charging time constant, TsIs a sampling rate parameter related to the sampling rate at which the signal to be examined is converted into a digital signal;
when the charge-discharge detection wave model discharges:
b0=0，b1=(1+2τdis/Ts)-1,a1=(1-2τdis/Ts)/ (1+2τdis/Ts),τdisis the discharge time constant, TsIs a sampling rate parameter related to the sampling rate at which the signal to be examined is converted into a digital signal.
Further, the quasi-peak detection is performed on the signal to be detected according to the modulus sequence, and the method further includes:
when k1 x y (n-1) is less than or equal to x (n), the charging mode is the first charging mode;
where x (n) is the modulus sequence input to the charge-discharge detection wave model, y (n) is the output sequence of the charge-discharge detection wave model, and k1 is a first slope constant.
Further, the obtaining of the quasi-peak detection parameters of the signal to be detected according to the modulus sequence further includes:
when k1 x y (n-1) is less than or equal to x (n), the charging mode is the first charging mode;
when k1 x y (n-1) is less than or equal to x (n) is less than k2 x y (n-1), the charging mode is the second charging mode;
wherein x (n) is the modulus sequence input to the charge-discharge detection wave model, y (n) is the output sequence of the charge-discharge detection wave model, k1 is a first slope constant, and k2 is a second slope constant.
Further, the quasi-peak detection is performed on the signal to be detected according to the modulus sequence, and the method further includes:
a first discharge mode when x (n) < k1 × y (n-1);
where x (n) is a modulus sequence input to the charge-discharge detection wave model, y (n) is an output sequence of the charge-discharge detection wave model, and k1 is a first slope constant.
Further, the quasi-peak detection of the signal to be detected according to the modulus sequence includes:
inputting the sequence of modulus values into a mechanical time model, the mechanical time model formula comprising:
y1(n)=c*x(n)+c*x(n-1)+d*y1(n-1);
y2(n)=c*y1(n)+c*y1(n-1)+d*y2(n-1);
wherein x (n) is an output sequence of the charge-discharge detection model, y1(n) is the output sequence of the mechanical time model output, y2(n) is a radical of1(n) input to the output sequence obtained by the mechanical time model, c = K(1/2)×(2×Tm×fs+1)-1,d=(2×Tm×fs-1)×(2×Tm×fs+1)-1Tm is a mechanical time constant, fs is a sampling rate constant related to the sampling rate at which the signal to be examined is converted into a digital signal, and K is the open-loop amplification factor of the mechanical time model.
According to a second aspect, there is provided in another embodiment a quasi-peak detector comprising:
the A/D conversion module is used for converting the signal to be detected into a digital signal;
a numerically controlled oscillator for mixing the digital signal to a zero frequency signal in a quadrature mixing manner to obtain a first mixing signal I and a second mixing signal Q;
the RBW module is used for filtering the first mixing signal I and the second mixing signal Q according to a preset bandwidth;
the module calculating module is used for calculating the module of the first mixing signal I and the second mixing signal Q after filtering so as to obtain a module value sequence;
and the quasi-peak detection module is used for carrying out quasi-peak detection on the signal to be detected according to the module value sequence.
Further, the quasi-peak detection module is configured to input the modulus sequence into a charge-discharge detection model, where the charge-discharge detection model formula includes:
y(n)=b0x(n)+b1x(n-1)-a1y(n-1);
wherein x (n) is the modulus sequence input to the charge-discharge detection wave model, and y (n) is the output sequence of the charge-discharge detection wave model;
when the charge-discharge detection wave model is charged:
b0=b1=(1+2τcha/Ts)-1,a1=(1-2τcha/Ts)/ (1+2τcha/Ts),τchais the charging time constant, TsIs a sampling rate parameter related to the sampling rate at which the signal to be examined is converted into a digital signal;
when the charge-discharge detection wave model discharges:
b0=0，b1=(1+2τdis/Ts)-1,a1=(1-2τdis/Ts)/ (1+2τdis/Ts),τdisis the discharge time constant, TsIs a sampling rate parameter related to the sampling rate at which the signal to be examined is converted into a digital signal;
when k1 x y (n-1) is less than or equal to x (n), the charging mode is the first charging mode;
wherein x (n) is the modulus sequence input to the charge-discharge detection wave model, y (n) is the output sequence of the charge-discharge detection wave model, and k1 is a first slope constant;
and/or the presence of a gas in the gas,
a first discharge mode when x (n) < k1 × y (n-1);
where x (n) is a modulus sequence input to the charge-discharge detection wave model, y (n) is an output sequence of the charge-discharge detection wave model, and k1 is a first slope constant.
According to the quasi-peak detection method and the quasi-peak detector of the embodiment, the quasi-peak detector comprises an A/D conversion module, a digital control oscillator, an RBW module, a module solving module and a quasi-peak detection module, a signal to be detected is converted into a digital signal, the obtained digital signal is mixed to a zero-frequency signal in an orthogonal frequency mixing mode, the obtained first frequency mixing signal I and the obtained second frequency mixing signal Q are filtered according to a preset bandwidth respectively, the filtered first frequency mixing signal I and the filtered second frequency mixing signal Q are subjected to modulus so as to obtain a modulus sequence, and finally the quasi-peak detection is carried out on the signal to be detected according to the modulus sequence. Because the quasi-peak detection is carried out after the signal to be detected is converted into the digital signal, the digitization of the quasi-peak detector is realized, and the quasi-peak detection is more accurate, faster and easy to store.
Drawings
FIG. 1 is a quasi-peak detection circuit;
FIG. 2 is a charge and discharge emphasis circuit for quasi-peak detection;
FIG. 3 is a preprocessing circuit for mechanical time constant acquisition;
FIG. 4 is a schematic block diagram of a quasi-peak detection circuit;
FIG. 5 is a block diagram model of a digital transfer function in an implementation;
FIG. 6 is a block diagram model of a digital transfer function in an implementation;
FIG. 7 is a flow diagram illustrating a quasi-peak detection method according to an embodiment;
FIG. 8 is a timing diagram of a modulo sequence in one embodiment;
FIG. 9 is a schematic diagram of a quasi-peak detector in one embodiment;
FIG. 10 is a timing diagram illustrating the modulo sequence in one embodiment.
Detailed Description
The present invention will be described in further detail with reference to the following detailed description and accompanying drawings. Wherein like elements in different embodiments are numbered with like associated elements. In the following description, numerous details are set forth in order to provide a better understanding of the present application. However, those skilled in the art will readily recognize that some of the features may be omitted or replaced with other elements, materials, methods in different instances. In some instances, certain operations related to the present application have not been shown or described in detail in order to avoid obscuring the core of the present application from excessive description, and it is not necessary for those skilled in the art to describe these operations in detail, so that they may be fully understood from the description in the specification and the general knowledge in the art.
Furthermore, the features, operations, or characteristics described in the specification may be combined in any suitable manner to form various embodiments. Also, the various steps or actions in the method descriptions may be transposed or transposed in order, as will be apparent to one of ordinary skill in the art. Thus, the various sequences in the specification and drawings are for the purpose of describing certain embodiments only and are not intended to imply a required sequence unless otherwise indicated where such sequence must be followed.
The numbering of the components as such, e.g., "first", "second", etc., is used herein only to distinguish the objects as described, and does not have any sequential or technical meaning. The term "connected" and "coupled" when used in this application, unless otherwise indicated, includes both direct and indirect connections (couplings).
The basic characteristics of the quasi-peak detector are specified in GB/T6113/CISPR16, and include the requirements of 6dB medium frequency bandwidth, charging and discharging time constant, critical damping indicator mechanical time constant, detector front circuit overload coefficient, and overload coefficient between the detector and the indicator. Wherein the charging time constant is the charging time constant from the instant when the constant sinusoidal voltage is applied to the input of the detector stage until the output voltage of the detector reaches 63% of its final value. The discharge time constant is the time taken from the moment when the constant sine wave voltage applied to the input terminal of the detector is removed until the output voltage of the detector drops to 37% of the initial value. The critical damping indicator has mechanical time constant reflecting some damping effect from quasi-peak detection output to indication, so that the charge and discharge process of the detector is hard to distinguish from the final voltage of the detector, and the A/D conversion is used to obtain the output voltage of the detector. As shown in Table 1, GB/T6113/CISPR16 specifies reference bandwidths of four frequency points of the quasi-peak detector, wherein the reference bandwidths are all 6dB bandwidths.
TABLE 1
Due to the difficulties of directly measuring the fundamental characteristics of the quasi-peak detector, there is a clear measurement method for receivers with quasi-peak detectors in GB/T6113/CISPR16, which measures the performance of the detector not directly but by detecting the absolute amplitude accuracy and relative relationship of the impulse response of the quasi-peak detector.
The quasi-peak detector is designed taking into account three factors:
1) the quasi-peak detection front has peak detection;
2) designing a charge and discharge time weighting circuit for the peak detector circuit;
3) a circuit capable of simulating the critical damping time mechanical constant of the quasi-peak detector should be included.
In addition to the above three-point quasi-peak detector, the overload factor of the circuit in front of the detector and the overload factor between the detector and the indicator must be satisfied.
Referring to fig. 1, a quasi-peak detector circuit includes an operational amplifier a11, a capacitor C11, and a diode D11, wherein an intermediate frequency signal to be detected is input from the positive electrode of the operational amplifier a11, a signal output from the output terminal of the operational amplifier a11 is used for quasi-peak parameter detection, the positive electrode of the diode D11 is connected to the negative electrode of the operational amplifier a11, the negative electrode of the diode D11 is connected to the output terminal of the operational amplifier a11, and the capacitor C11 is connected in series to the two ends of the diode D11.
Referring to fig. 2, a charge and discharge emphasis circuit for quasi-peak detection includes a resistor R21, a resistor R22, a resistor R23, a resistor R24, a capacitor C21, an inductor L21, and a diode D21. The diode D21, the resistor R23, the inductor L21 and the resistor R24 are sequentially connected in series between the input end and the output end of the charging and discharging emphasis circuit, the resistor R21 is connected in series between the connection end of the diode D21 and the resistor R23 and the ground GND, and the capacitor C21 is connected between the output end of the charging and discharging emphasis circuit and the ground GND.
Referring to fig. 3, a preprocessing circuit for obtaining a mechanical time constant includes a resistor R31, a resistor R32, a resistor R33, a resistor R34, a capacitor C31, a capacitor C32, and an operational amplifier a 31. The output end of the operational amplifier A31 is used as the output end of the preprocessing circuit, and the resistor R31 and the resistor R32 are connected in series between the input end of the preprocessing circuit and the negative input end of the operational amplifier A31. The capacitor C31 is connected between the negative input terminal of the operational amplifier a31 and the ground GND, the capacitor C32 is connected between the connection terminal of the resistor R31 and the resistor R32 and the output terminal of the operational amplifier a31, the resistor R33 is connected between the positive input terminal of the operational amplifier a31 and the ground GND, and the resistor R34 is connected between the positive input terminal and the output terminal of the operational amplifier a 31.
The intermediate frequency signal to be measured reaches the standard of a charging time constant and a discharging time constant after being processed by the charging and discharging weighting circuit, and then the charging and discharging weighted voltage signal is processed by the analog circuit for the mechanical time constant of the critical damping indicator, and finally the voltage of the quasi-peak detector is formed and output to the damping meter. The various parameters of the calibration quasi-peak detector may be based on the basic characteristics of the quasi-peak detector as specified in GB/T6113/CISPR16, as shown in table 2:
TABLE 2
The pulse intensities of the reference signals applied by the quasi-peak detector are different under different bandwidths, and the pulse intensity is also called pulse area, and is defined as the area of a certain pulse voltage integrated with time. The quasi-peak detector is realized by adopting an analog circuit, the detection result of the quasi-peak detector is influenced by the performance of an analog device, the temperature of a working environment and other factors, and the problems of large measurement error, poor stability, difficult parameterization, low flexibility, low measurement speed and the like exist.
For convenience of explanation of the digital quasi-peak detector in the pre-protection of the present application, the quasi-peak detector is simplified, please refer to fig. 4, which is a schematic block diagram of a quasi-peak detector circuit, and the quasi-peak detector includes a charge and discharge circuit and a damping meter. Wherein, U (t)Intermediate frequency signal, U, output by envelope detection circuit2(t) is a quasi-peak detection output signal, the damping meter is used for indicating peak voltage, the charging time constant of the quasi-peak detection circuit is determined by a resistor R1 and a capacitor C, the discharging time constant is determined by a resistor R2 and a capacitor C, the discharging time of the quasi-peak detection circuit is much longer than the charging time, so R2>>And R1. Then U (t) and U2(t) has:
U2(S)= U(S)×（SC+R2 -1）-1×[R1+(SC+ R2 -1)-1]-1;
its transfer function is then:
H(s)=U2(s)/U(s)=（SC+R2 -1）-1×[R1+(SC+ R2 -1)-1]-1
=R2×(R1+R2) -1×[1+S×R1×R2×(R1+R2)-1×C]-1
because of R2>>R1, said R2×（R1+R2）-1Approximately equal to 1, the transfer function can be approximated as:
H(s)=U2(s)/U(s)= [1+S×R1×R2×(R1+R2)-1×C]-1
=(1+Sτ)-1,(τ= R1×R2×(R1+R2)-1×C);
the transfer function is subjected to analog-digital conversion by adopting a double-line row conversion method, and the mapping relation is as follows:
s=2×Ts-1×(1-z-1) ×(1+z-1) -1;
where Ts is the sampling rate of the digital signal.
Referring to fig. 5, a block diagram of a digital transfer function in an implementation is shown, where x (n) is an input sequence and y (n) is an output sequence, and the transformed digital transfer function is:
H（z）=(b0+b1z-1)(1+a1z-1)-1;
wherein, b0=b1=(1+2τfs)-1，a1=(1-2τfs) ×(1+2τfs)-1。
The charge/discharge determination condition is the magnitude relationship between x (n) and y (n-1).
And when the quasi-peak detector is charged:
y(n)=b0x(n)+b1 x (n-1)-a1y(n-1);
wherein, b0=b1=(1+2τcha/Ts)-1，a1=(1-2τcha/Ts) ×(1+2τcha/Ts)-1,τchaIs the charging time constant.
Discharge time b of quasi-peak detector0=0, then:
y(n)=b1 x (n-1)-a1y(n-1);
wherein, b1=(1+2τdis/Ts)-1，a1=(1-2τdis/Ts) ×(1+2τdis/Ts)-1,τdisIs the discharge time constant.
The mechanical time constant (Tm) is realized by adopting circuit simulation, and the motion equation of the critical damping indicator is given in the GB/T6113/CISPR16 specification:
TM 2(d2a/dt2)+2 TM(da/dt)+a=ki;
where a is the bias indication for the critical damping indicator, i is the current flowing through the critical damping indicator, and k is the time constant of the critical damping indicator.
Performing a single-sided laplace transform on the motion equation of the critical damping indicator, and setting Y (0) = Y' (0), the transfer function is:
H（s）=Y(s)/X(s)=K×[(Tm×s+1) ×( Tm×s+1)]-1;
then, a bilinear transformation method is used to perform analog-to-digital transformation on the transfer function, please refer to fig. 6, which is a block diagram model of a digital transfer function in implementation, where x (n) is an input sequence, y (n) is an output sequence, and the transformed digital transfer function is:
H（z）=[c×(1+ z-1) ×(1-d z-1)-1 ] × [c×(1+ z-1) ×(1-d z-1)-1 ];
wherein, c = K(1/2)×(2×Tm×fs+1)-1,d=(2×Tm×fs-1)×(2×Tm×fs+1)-1。
From the z expression, the transformed digital transfer function is a cascade of 2 identical first-order subsystems, and the time domain expression is:
y1(n)=c×x(n)+c×x(n-1)+d×y1(n-1);
y2(n)=c×y1(n)+c×y1(n-1)+d×y2(n-1);
the coefficients c and d may be obtained according to a time domain expression.
In summary, after analog-to-digital conversion of the transfer function, the alignment peak detector can be digitized.
In the embodiment of the application, a quasi-peak detection method and a quasi-peak detector are disclosed, and the quasi-peak detector comprises an A/D conversion module, a digital control oscillator, a RBW module, a module and a quasi-peak detection module, wherein a signal to be detected is converted into a digital signal, the obtained digital signal is mixed to a zero-frequency signal in an orthogonal frequency mixing mode, the obtained first frequency mixing signal I and the obtained second frequency mixing signal Q are filtered according to a preset bandwidth, the filtered first frequency mixing signal I and the filtered second frequency mixing signal Q are subjected to modulus so as to obtain a modulus sequence, and finally, the quasi-peak detection is performed on the signal to be detected according to the modulus sequence. Because the quasi-peak detection is carried out after the signal to be detected is converted into the digital signal, the digitization of the quasi-peak detector is realized, and the quasi-peak detection is more accurate, faster and easy to store.
Example one
Referring to fig. 7, a flowchart of a quasi-peak detection method in an embodiment includes:
step 100, acquiring a digital signal.
The signal to be detected is converted into a digital signal using an a/D converter.
Step 200, obtaining a mixing signal.
The digital signal is mixed to a zero frequency signal in a quadrature mixing manner to obtain a first mixing signal I and a second mixing signal Q. In one embodiment, a digital control oscillator is used to perform quadrature mixing on a signal to be detected converted into a digital signal to a zero frequency signal to obtain a first mixing signal I and a second mixing signal Q. In an embodiment, the obtained first mixing signal I and the second mixing signal Q are down-sampled, and the down-sampling may be performed by using CIC decimation and/or half-band decimation, so as to reduce the amount of data post-processing.
Step 300, filtering the mixed signal.
And respectively filtering the first mixing signal I and the second mixing signal Q according to a preset bandwidth. In an embodiment, the first mixing signal I and the second mixing signal Q are filtered with 6dB gaussian bandwidth, respectively. In an embodiment, the first mixing signal I and the second mixing signal Q are subjected to 6dB gaussian bandwidth filtering in multiple frequency ranges for later-stage selection, where the multiple frequency ranges can refer to reference bandwidths of four frequency points specified in GB/T6113/CISPR16, and are all 6dB bandwidths.
In step 400, the mixed signal is modulo to obtain a modulo sequence.
And performing modulus operation on the filtered first mixing signal I and the filtered second mixing signal Q to obtain a modulus value sequence. In one embodiment, the module value sequence is arranged according to the module value acquisition sequence, and the acquisition time intervals of any two adjacent module values are equal and related to the analog-to-digital conversion frequency and the down-sampling frequency of the signal to be detected.
Step 500, quasi-peak detection.
And carrying out quasi-peak detection on the signal to be detected according to the modulus sequence. In one embodiment, the quasi-peak detection of the signal to be detected according to the modulus sequence includes:
inputting the module value sequence into a charge-discharge detection model, wherein the charge-discharge detection model formula comprises:
y(n)=b0x(n)+b1x(n-1)-a1y(n-1);
where x (n) is a modulus sequence of the input charge-discharge detection model, and y (n) is an output sequence of the charge-discharge detection model.
When the charge-discharge detection wave model is charged:
b0=b1=(1+2τcha/Ts)-1,a1=(1-2τcha/Ts)/ (1+2τcha/Ts),τchais the charging time constant, TsIs a sampling rate parameter related to the sampling rate at which the signal to be examined is converted into a digital signal;
when the charge-discharge detection wave model discharges:
b0=0，b1=(1+2τdis/Ts)-1,a1=(1-2τdis/Ts)/ (1+2τdis/Ts),τdisis the discharge time constant, TsIs a sampling rate parameter related to the sampling rate at which the signal to be examined is converted into a digital signal.
When k1 x y (n-1) ≦ x (n), it is the first charging mode. Where x (n) is a modulus sequence of the input charge-discharge detection model, y (n) is an output sequence of the charge-discharge detection model, and k1 is a first slope constant.
Referring to FIG. 8, a timing diagram of an exemplary modulus sequence is shown, wherein the ordinate represents modulus and the abscissa represents modulus sequence number N. Because the envelope detection of the modular value sequence in the analog quasi-peak detection is realized by a diode, the charging can be divided into two sections to correspond to two charging slopes, and the discharging only has one slope. In one embodiment, the first charging mode and the second charging mode of the charge-discharge detection model, as shown in fig. 8, include the curve k1 being the first charging mode and the curve k2 being the second charging mode, then:
when k1 x y (n-1) is less than or equal to x (n), the charging mode is the first charging mode;
when k1 x y (n-1) is less than or equal to x (n) is less than k2 x y (n-1), the charging mode is the second charging mode;
wherein x (n) is a modulus sequence of the input charge-discharge detection model, y (n) is an output sequence of the charge-discharge detection model, k1 is a first slope constant, and k2 is a second slope constant.
When x (n) < k1 × y (n-1), the first discharge mode is established.
Where x (n) is a modulus sequence of the input charge-discharge detection model, y (n) is an output sequence of the charge-discharge detection model, and k1 is a first slope constant.
The values of the first slope constant k1 and the second slope constant k2 correspond to the following table:
| Band | A | | C&D |
| k1 | |||
| 1 | 1 | 1 | |
| |
1 | 2.5 | 4.15 |
the bands A, B, C and D are referred to GB/T6113/CISPR16 specification requirements, and proper calibration is actually carried out, as shown in the following table:
the obtaining of the critical damped mechanical time constant (Tm) comprises:
inputting an output sequence of the charge-discharge detection wave model into a mechanical time model, wherein a mechanical time model formula comprises:
y1(n)=c*x(n)+c*x(n-1)+d*y1(n-1);
y2(n)=c*y1(n)+c*y1(n-1)+d*y2(n-1);
wherein x (n) is the output sequence of the charge-discharge detection model, y1(n) is the output sequence of the mechanical time model output, y2(n) is a radical of1(n) input to the output sequence obtained by the mechanical time model, c = K(1/2)×(2×Tm×fs+1)-1,d=(2×Tm×fs-1)×(2×Tm×fs+1)-1Tm is the mechanical time constant, fs is the sampling rate constant associated with the sampling rate parameter of the signal to be examined converted into a digital signal, and K is the open loop amplification of the mechanical time model.
According to the quasi-peak detection method of the embodiment, a signal to be detected is converted into a digital signal, the obtained digital signal is mixed to a zero-frequency signal in a quadrature mixing mode, the obtained first mixing signal I and the obtained second mixing signal Q are filtered according to a preset bandwidth, a modulus is taken for the filtered first mixing signal I and the filtered second mixing signal Q to obtain a modulus sequence, and finally the quasi-peak detection is performed on the signal to be detected according to the modulus sequence. Because the signal to be detected is converted into a digital signal and then quasi-peak detection is carried out on the signal to be detected, the digitization of the quasi-peak detector is realized, and the quasi-peak detection is more accurate, faster and easy to store.
Example two
Referring to fig. 9, a circuit structure of a quasi-peak detector in an embodiment is schematically shown, which includes an a/D conversion module 10, a numerically controlled oscillator 20, an RBW module 30, a modulus module 40, and a quasi-peak detection module 50. The a/D conversion module 10 is used to convert the signal to be detected into a digital signal. The numerically controlled oscillator 20 is configured to mix the digital signal to a zero-frequency signal in a quadrature mixing manner to obtain a first mixing signal I and a second mixing signal Q. The RBW block 30 is configured to filter the first mixing signal I and the second mixing signal Q according to a predetermined bandwidth. The modulo module 40 is configured to modulo the filtered first mixing signal I and the second mixing signal Q to obtain a modulo sequence. The quasi-peak detection module 50 is used for performing quasi-peak detection on the signal to be detected according to the modulus sequence. The quasi-peak detection module 50 is configured to input a modulus sequence into a charge-discharge detection model, where the charge-discharge detection model formula includes:
y(n)=b0x(n)+b1x(n-1)-a1y(n-1);
where, x (n) is a modulus sequence of the input charge-discharge detection model, and y (n) is an output sequence of the charge-discharge detection model.
When the charge-discharge detection wave model is charged:
b0=b1=(1+2τcha/Ts)-1,a1=(1-2τcha/Ts)/ (1+2τcha/Ts),τchais the charging time constant, TsIs a sampling rate parameter related to the sampling rate at which the signal to be examined is converted into a digital signal.
When the charge-discharge detection wave model discharges:
b0=0，b1=(1+2τdis/Ts)-1,a1=(1-2τdis/Ts)/ (1+2τdis/Ts),τdisis the discharge time constant, TsIs a sampling rate parameter related to the sampling rate at which the signal to be examined is converted into a digital signal.
When k1 x y (n-1) ≦ x (n), it is the first charging mode. Where x (n) is a modulus sequence of the input charge-discharge detection model, y (n) is an output sequence of the charge-discharge detection model, and k1 is a first slope constant.
When x (n) < k1 × y (n-1), the first discharge mode is shown, where x (n) is a sequence of mode values of the input charge-discharge detection model, y (n) is a sequence of outputs of the charge-discharge detection model, and k1 is a first slope constant.
The first slope constant k1 may take on the following table:
| Band | A | | C&D |
| k1 | |||
| 1 | 1 | 1 |
wherein, the wave bands A, B, C and D refer to the GB/T6113/CISPR16 specification requirements, as shown in the following table:
obtaining a critical damped mechanical time constant (Tm) comprises:
inputting an output sequence of the charge-discharge detection wave model into a mechanical time model, wherein a mechanical time model formula comprises:
y1(n)=c*x(n)+c*x(n-1)+d*y1(n-1);
y2(n)=c*y1(n)+c*y1(n-1)+d*y2(n-1);
wherein x (n) is an output sequence of the charge-discharge detection model, y1(n) is the output sequence of the mechanical time model output, y2(n) is a radical of1(n) input to the output sequence obtained by the mechanical time model, c = K(1/2)×(2×Tm×fs+1)-1,d=(2×Tm×fs-1)×(2×Tm×fs+1)-1Tm is the mechanical time constant, fs is the sampling rate constant associated with the sampling rate parameter of the signal to be examined converted into a digital signal, and K is the open loop amplification of the mechanical time model.
In an embodiment, the dco 20 further includes a decimation module 21, where the decimation module 21 down-samples the acquired first mixing signal I and second mixing signal Q and outputs the down-sampled signals to the RBW module 30, and the down-sampling may be performed by CIC decimation and/or half-band decimation, so as to reduce the amount of data post-processing. The quasi-peak detection module 50 in the embodiment of the present application may be implemented by FPGA hardware or by computational software simulation.
Referring to fig. 10, a timing diagram of an exemplary module value sequence is shown, wherein the ordinate represents module values and the abscissa represents the module value sequence number N. The curve L0 is a module value sequence curve, the curve L1 is a module value curve of the interference signal in the module value sequence, the curve L2 is a charging and discharging curve of the interference signal, and the trapezoidal line L3 is a preset reference value. Quasi-peak detection can be achieved according to whether the charging and discharging curve L2 of the interference signal exceeds the preset reference value of the trapezoidal line L3.
Those skilled in the art will appreciate that all or part of the functions of the various methods in the above embodiments may be implemented by hardware, or may be implemented by computer programs. When all or part of the functions of the above embodiments are implemented by a computer program, the program may be stored in a computer-readable storage medium, and the storage medium may include: a read only memory, a random access memory, a magnetic disk, an optical disk, a hard disk, etc., and the program is executed by a computer to realize the above functions. For example, the program may be stored in a memory of the device, and when the program in the memory is executed by the processor, all or part of the functions described above may be implemented. In addition, when all or part of the functions in the above embodiments are implemented by a computer program, the program may be stored in a storage medium such as a server, another computer, a magnetic disk, an optical disk, a flash disk, or a portable hard disk, and may be downloaded or copied to a memory of a local device, or may be version-updated in a system of the local device, and when the program in the memory is executed by a processor, all or part of the functions in the above embodiments may be implemented.
The present invention has been described in terms of specific examples, which are provided to aid understanding of the invention and are not intended to be limiting. For a person skilled in the art to which the invention pertains, several simple deductions, modifications or substitutions may be made according to the idea of the invention.
Claims (9)
1. A quasi-peak detection method, comprising:
converting the signal to be detected into a digital signal;
mixing the digital signal to a zero-frequency signal in a quadrature mixing mode to obtain a first mixing signal I and a second mixing signal Q;
filtering the first mixing signal I and the second mixing signal Q according to a preset bandwidth respectively;
performing modulo on the filtered first mixing signal I and the filtered second mixing signal Q to obtain a modulus sequence;
and carrying out quasi-peak detection on the signal to be detected according to the modulus sequence.
2. The quasi-peak detection method according to claim 1, wherein said mixing said digital signal to a zero frequency signal in quadrature mixing to obtain a first mixed signal I and a second mixed signal Q, further comprises:
the first mixing signal I and the second mixing signal Q are down-sampled before being filtered according to a preset bandwidth.
3. The quasi-peak detection method of claim 1, wherein the predetermined bandwidth comprises a 6dB bandwidth.
4. The quasi-peak detection method according to claim 1, wherein the quasi-peak detection of the signal to be detected according to the modulus sequence comprises:
inputting the modulus sequence into a charge and discharge detection model, wherein the charge and discharge detection model formula comprises:
y(n)=b0x(n)+b1x(n-1)-a1y(n-1)；
wherein x (n) is the modulus sequence input to the charge-discharge detection wave model, and y (n) is the output sequence of the charge-discharge detection wave model;
when the charge-discharge detection wave model is charged:
b0=b1=(1+2τcha/Ts)-1，a1=(1-2τcha/Ts)/ (1+2τcha/Ts)，τchais the charging time constant, TsIs a sampling rate parameter related to the sampling rate at which the signal to be examined is converted into a digital signal;
when the charge-discharge detection wave model discharges:
b0=0，b1=(1+2τdis/Ts)-1，a1=(1-2τdis/Ts)/ (1+2τdis/Ts)，τdisis the discharge time constant, TsIs a sampling rate parameter related to the sampling rate at which the signal to be examined is converted into a digital signal.
5. The quasi-peak detection method according to claim 4, wherein said quasi-peak detecting said signal to be detected according to said sequence of mode values, further comprises:
when k1 x y (n-1) is less than or equal to x (n), the charging mode is the first charging mode;
where x (n) is the modulus sequence input to the charge-discharge detection model, y (n) is the output sequence of the charge-discharge detection model, and k1 is a first slope constant.
6. The quasi-peak detection method according to claim 4, wherein said quasi-peak detecting said signal to be detected according to said sequence of mode values, further comprises:
a first discharge mode when x (n) < k1 × y (n-1);
where x (n) is a modulus sequence input to the charge-discharge detection wave model, y (n) is an output sequence of the charge-discharge detection wave model, and k1 is a first slope constant.
7. The quasi-peak detection method according to claim 4, wherein the quasi-peak detection of the signal to be detected according to the modulus sequence comprises:
inputting the sequence of modulus values into a mechanical time model, the mechanical time model formula comprising:
y1(n)=c*x(n)+c*x(n-1)+d*y1(n-1)；
y2(n)=c*y1(n)+c*y1(n-1)+d*y2(n-1)；
wherein x (n) is the modulus sequence input to the charge-discharge detection wave model, y1(n) is the output sequence of the mechanical time model output, y2(n) is a radical of1(n) input to the output sequence obtained by the mechanical time model, c = K(1/2)×(2×Tm×fs+1)-1，d=(2×Tm×fs-1)×(2×Tm×fs+1)-1Tm is a mechanical time constant, fs is a sampling rate constant related to the sampling rate at which the signal to be examined is converted into a digital signal, and K is the open-loop amplification factor of the mechanical time model.
8. A quasi-peak detector, comprising:
the A/D conversion module is used for converting the signal to be detected into a digital signal;
the digital control oscillator is used for mixing the digital signal to a zero-frequency signal in a quadrature mixing mode so as to obtain a first mixing signal I and a second mixing signal Q;
the RBW module is used for filtering the first mixing signal I and the second mixing signal Q according to a preset bandwidth;
the module calculating module is used for calculating the module of the first mixing signal I and the second mixing signal Q after filtering so as to obtain a module value sequence;
and the quasi-peak detection module is used for carrying out quasi-peak detection on the signal to be detected according to the module value sequence.
9. The quasi-peak detector of claim 8, wherein the quasi-peak detection module is configured to input the sequence of mode values into a charge-discharge detection model, the charge-discharge detection model formulation comprising:
y(n)=b0x(n)+b1x(n-1)-a1y(n-1)；
wherein x (n) is the modulus sequence input to the charge-discharge detection wave model, and y (n) is the output sequence of the charge-discharge detection wave model;
when the charge-discharge detection wave model is charged:
b0=b1=(1+2τcha/Ts)-1，a1=(1-2τcha/Ts)/ (1+2τcha/Ts)，τchais the charging time constant, TsIs a sampling rate parameter related to the sampling rate at which the signal to be examined is converted into a digital signal;
when the charge-discharge detection wave model discharges:
b0=0，b1=(1+2τdis/Ts)-1，a1=(1-2τdis/Ts)/ (1+2τdis/Ts)，τdisis the discharge time constant, TsIs a sampling rate parameter related to the sampling rate at which the signal to be examined is converted into a digital signal.
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