A broadband communication signal effective value measurement method and system

Abstract

The present invention provides a method and system for measuring the effective value of a broadband communication signal, belonging to the technical field of communication signal parameter measurement. The present invention divides a broadband communication signal into two paths, performs oversampling modulation on the first path signal according to a first oversampling clock to obtain a first data stream; and performs oversampling modulation on the second path signal according to a second oversampling clock to obtain a second data stream; the frequency of the first oversampling clock is different from the frequency of the second oversampling clock. The product of the first data stream and the second data stream is digitally filtered to obtain an instantaneous product signal, and the effective value of the broadband communication signal is determined based on the instantaneous product signal. The effective values ​​of the high-frequency and low-frequency components of the measured signal are converted into DC components, while retaining the randomness and high-frequency characteristics of the quantization noise, so as to facilitate further filtering and decimation of the quantization noise through filtering and truncation averaging, thereby obtaining an effective value measurement result, thereby improving the bandwidth and accuracy of the effective value measurement.

Description

Technical Field

[0001] The present invention relates to a method and system for measuring the effective value of a broadband communication signal, belonging to the technical field of communication signal parameter measurement. Background Art

[0002] Currently, OFDM (Orthogonal Frequency Division Multiplexing) modulation technology has been widely adopted in various communications fields. For example, OFDM-based broadband power line carrier communications and wireless communications are used in the field of power consumption information collection. These OFDM-based broadband communication signals have a wide frequency bandwidth. For example, the high-speed carrier HPLC communication defined by the State Grid Corporation of China's corporate standard has four selectable frequency bands: 1.953 MHz to 11.96 MHz, 2.441 MHz to 5.615 MHz, 0.781 MHz to 2.930 MHz, and 1.758 MHz to 2.930 MHz. In practical field applications, rapid assessment of the energy, or effective value, of broadband communication signals is required. For example, this is used to analyze channel occupancy in wireless communications and to quickly assess signal strength and channel attenuation during communications maintenance. However, due to the large bandwidth occupied by broadband signals, traditional measurement methods require either double the bandwidth or the highest-frequency analog-to-digital conversion to obtain the complete signal before further analysis of the signal energy using a digital processor. This not only places high demands on the performance of the analog-to-digital converter, but also generates a large amount of sampled data and the corresponding computational complexity.

[0003] Currently, an oversampling modulation technology is widely used in the analog-to-digital conversion of low-frequency signals. Figure 1 This is the principle of first-order oversampling analog-to-digital conversion, as described in "Hardware Implementation of Σ-Δ Analog-to-Digital Converters in Intelligent Instruments," published in the January 2011 issue of "Modern Measurement and Laboratory Management." The analog input signal Ain is subtracted from the output of a 1-bit DAC and fed into an integrator. The integrator's output and the zero-level value are then fed into a comparator, which updates the comparator's output value under clock control at the oversampling rate. This comparator is also known as a 1-bit quantizer. The high and low levels of the comparator's output control the 1-bit DAC, causing it to output two levels: +Vref and -Vref. This circuit implements 1-bit oversampling modulation, generating a 1-bit data stream. Through digital filtering and downsampling, the sampled data of the analog input signal Ain is finally obtained. Due to its low cost, this oversampling analog-to-digital converter is widely used in low-frequency signal measurement.

[0004] However, the above-mentioned oversampling modulation method uses filtered sampling, which limits the effective bandwidth of the method's analog-to-digital conversion. For broadband signals with a large bandwidth, the high-frequency components after the low-bandwidth oversampling analog-to-digital conversion are filtered out. The effective value of the signal obtained by further using the square average and square root does not contain high-frequency components, resulting in large errors and low accuracy. Summary of the Invention

[0005] The purpose of the present invention is to provide a method and system for measuring the effective value of a broadband communication signal, which is used to solve the problem that the existing oversampling modulation method has limited signal bandwidth and cannot effectively measure the broadband communication signal.

[0006] In order to achieve the above object, the present invention provides a method for measuring the effective value of a broadband communication signal, comprising the following steps:

[0007] 1) dividing a broadband communication signal into two paths, oversampling and modulating the first path signal according to a first oversampling clock to obtain a first data stream; oversampling and modulating the second path signal according to a second oversampling clock to obtain a second data stream; the frequency of the first oversampling clock and the frequency of the second oversampling clock are different;

[0008] 2) Performing digital filtering on the product of the first data stream and the second data stream to obtain an instantaneous product signal, and determining the effective value of the broadband communication signal based on the instantaneous product signal.

[0009] The data stream of a broadband communication signal after oversampling modulation contains a large amount of high-frequency quantization noise and useful signals. The high-frequency quantization noise is a random signal that varies erratically and is located in the high-frequency range of the oversampling modulation frequency. The useful signal is a signal with a certain regularity and is located in a frequency range lower than the oversampling modulation frequency. Multiplying the first and second data streams directly converts the measured effective value of the signal into a DC component while retaining the quantization random noise located in the high-frequency range. This facilitates subsequent digital filtering to extract the effective value component of the signal after filtering out the high-frequency quantization noise, thereby improving the bandwidth and accuracy of the effective value measurement. Furthermore, the oversampling clocks of the two oversampling modulations are set to different values ​​to avoid correlation between the quantization noise of the two oversampling modulation outputs. This ensures that the noise component of the two oversampling modulation output data streams, after multiplication, is irregular and remains a random signal, allowing it to be removed through filtering and truncated averaging. Based on the above principles, the present invention converts the effective values ​​of the high-frequency and low-frequency components of the measured signal into DC components, while still retaining the randomness and high-frequency characteristics of the quantization noise, making it easier to further filter out the quantization noise through filtering extraction and truncation averaging, thereby obtaining the effective value measurement result, thereby improving the bandwidth and accuracy of the effective value measurement.

[0010] Furthermore, in the above-mentioned method for measuring the effective value of a broadband communication signal, the second signal needs to be proportionally adjusted before being oversampled and modulated according to the second oversampling clock, and the adjustment coefficient K of the proportional adjustment is less than 1 and not less than 0.5; after multiplying the instantaneous product signal by the inverse of the adjustment coefficient K, the effective value of the broadband communication signal is determined.

[0011] The purpose of proportional adjustment of the second signal is to further increase the difference between the product result of the high-frequency quantization noise signal and the product result of the useful signal to be measured, so that the subsequent digital filtering processing can filter out the high-frequency quantization noise signal while retaining more useful signals to be measured, thereby reducing the loss of useful signals to be measured in broadband communication signals and improving the accuracy of effective value measurement.

[0012] Furthermore, in the above-mentioned broadband communication signal effective value measurement method, the ratio of the frequency of the first sampling clock to the frequency of the second sampling clock is P, and P is an integer greater than 1.

[0013] Furthermore, in the above-mentioned broadband communication signal effective value measurement method, the digital filtering process in step 2) includes integral comb filtering, filtering extraction and finite impulse response gain compensation filtering.

[0014] Due to the large amount of signal transmission in broadband communication signals, the filtering process requires a high processing speed. Integral comb filtering has a simple structure and high processing efficiency, so it is selected to process the product of the two data streams.

[0015] Furthermore, in the above-mentioned broadband communication signal effective value measurement method, the transfer function of the integral comb filter is:

[0016]

[0017] Wherein, G is the index of the integral comb filter, D is the delay factor, and M is the ratio of the sampling frequency of the first-pass oversampling modulation to the filtering decimation sampling frequency.

[0018] Furthermore, in the above-mentioned broadband communication signal effective value measurement method, the transfer function of the finite impulse response gain compensation filter is:

[0019]

[0020] Among them, x(n) is the input data sequence, y(n) is the output data sequence, N cmp is the order of the FIR gain compensation filter.

[0021] Furthermore, in the above-mentioned broadband communication signal effective value measurement method, in step 1), the oversampling modulation of the first signal and the second signal both adopts a second-order oversampling modulator, and the second-order oversampling modulator is a second-order Σ-Δ oversampling modulator.

[0022] Furthermore, in the above-mentioned broadband communication signal effective value measurement method, the method also includes performing analog low-pass filtering on the broadband signal before dividing the broadband signal into two paths, and the analog low-pass filtering adopts a second-order Butterworth low-pass filter.

[0023] The second-order Butterworth low-pass filter is a commonly used filter type with the characteristics of simple structure and convenient calculation.

[0024] Furthermore, in the above-mentioned method for measuring the effective value of a broadband communication signal, the effective value of the broadband communication signal is obtained by averaging the instantaneous product signal and then taking the square root.

[0025] The present invention also provides a broadband communication signal effective value measurement system, which includes a processor and a memory, wherein the processor adopts the above-mentioned broadband communication signal effective value measurement method. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 A schematic diagram of a conventional first-order oversampling analog-to-digital conversion circuit;

[0027] Figure 2 It is a schematic diagram of the principle of the present invention;

[0028] Figure 3 4 is a structural diagram of a second-order oversampling modulator used in an embodiment of the method of the present invention;

[0029] Figure 4 The broadband communication signal S is simulated and inputted by the embodiment of the method of the present invention. IN The amplitude-frequency characteristic curve of

[0030] Figure 5 is the effective value R of 100 measurements output in the embodiment of the method of the present invention m Statistical histogram of errors;

[0031] Figure 6 Schematic diagram of the structure of the system embodiment of the present invention. DETAILED DESCRIPTION

[0032] In order to make the objectives, technical solutions and advantages of the present invention more clear, the present invention is further described in detail below with reference to the accompanying drawings and embodiments.

[0033] like Figure 2 As shown, the present invention's method for measuring the effective value of a broadband communication signal involves filtering and preprocessing the broadband communication signal, performing two-way oversampling modulation on the preprocessed broadband communication signal, digitally filtering and extracting the product of the two 1-bit signals obtained by the oversampling modulation, and finally obtaining the effective value measurement data of the broadband communication signal through truncated averaging and square root calculation. Furthermore, to increase the difference between the two oversampling modulation results, a frequency reduction factor is set to make the clock frequencies of the two oversampling modulation channels inconsistent, and a proportional coefficient is adjusted for one of the channels.

[0034] Method Example:

[0035] 1) Obtain the broadband communication signal to be measured and perform preprocessing.

[0036] Since there are a lot of high-frequency noise signals in the broadband communication signal to be measured, it is necessary to perform low-pass filtering on the broadband communication signal first. Assume that the broadband communication signal to be measured is s IN , will s IN An analog low-pass filtering process is performed to obtain an analog filtered signal. The analog low-pass filtering in this embodiment uses an analog second-order Butterworth filter with a corner frequency of 1 MHz. The gain of this filter is close to 1 and the phase shift is close to 0 below 500 kHz. As other embodiments, the low-pass filtering process of the present invention can also use other low-pass filters, such as Butterworth filters and Chevrolet filters of other orders.

[0037] 2) The preprocessed signal is divided into two paths, and oversampling and modulating are performed on each of them to obtain two data streams.

[0038] The analog filtered signal is divided into two paths, the first signal is s' IN , the second signal is s" IN , for the first signal s' IN Oversampling modulation is performed according to the first oversampling clock to obtain a first 1-bit data stream s 1bit , the sampling frequency of the first oversampling modulation process is equal to the oversampling clock frequency f ov Same; for analog conditioning signal s" IN Perform the second oversampling modulation process to obtain the second 1-bit data stream s 2bit The sampling frequency of the second oversampling modulation process is the result of the oversampling clock frequency being P times lowered, that is, f ov / P. In this embodiment, the oversampling clock frequency f ov =10.24MHz, the frequency reduction coefficient P is 2, then the sampling frequency f of the second oversampling modulation process is ov / P=5.12MHz. In addition, the second signal s" IN Multiply by the adjustment coefficient K, the adjusted signal s" IN Perform the second oversampling modulation process to obtain the second 1-bit data stream s 2bit , where the value of K is not less than 0.5 and less than 1. In this embodiment, K is 0.5.

[0039] The first oversampling modulation and the second oversampling modulation are both adopted as follows Figure 3The second-order Σ-Δ oversampling modulator shown in the figure differs only in the clock frequency of the digital quantizer. The difference between the input analog signal and the quantizer output is taken, and the difference signal is input to the first integrator. The difference between the first integrator output and the quantizer output is taken, and the difference signal is input to the second integrator. The transfer function of the first integrator is: The transfer function of the second integrator is The output result of the second integrator is input to the quantizer. Under different sampling frequency control, when the input w≥0, the quantizer outputs y=1; when the input w<0, the output y=-1, then y(n) is the oversampling modulation result.

[0040] If the first oversampling modulation process and the second oversampling modulation process use the same oversampling clock signal and the same input amplitude, the 1-bit data streams output by the two oversampling modulations will be highly correlated. This means that the quantization noise signal and the useful signal in the two analog signals are difficult to distinguish by the subsequent digital filter. This results in the subsequent digital filtering process filtering out both the high-frequency quantization noise signal and part of the useful signal. Alternatively, while retaining the useful signal, it also retains part of the high-frequency quantization noise signal, causing errors in the effective value calculation process and affecting the accuracy of the effective value calculation. Therefore, the present invention introduces an adjustment coefficient K and a frequency reduction coefficient P to increase the difference between the quantization noise signal and the useful signal to be measured, facilitating the filter to perform filtering processing.

[0041] 3) Calculate the product of the two data streams and perform digital filtering and extraction processing on them to obtain the instantaneous product signal, and use it to determine the effective value.

[0042] The first 1-bit data stream s 1bit and the second 1-bit data stream s 2bit The product of 1 bit data stream q 1bit ; Then multiply the product 1 bit data stream q 1bit After digital filtering and extraction, the instantaneous product signal q can be obtained s The digital filtering extraction used includes three steps, namely integral comb filtering, sampling multiple extraction and finite impulse response gain compensation filtering. The transfer function of the integral comb filter is:

[0043]

[0044] Among them, G is the index of the integral comb filter, D is the delay factor, and M is the sampling multiple; in this implementation, G is 3, D is 1, and M is 2048.

[0045] The clock for the sampling multiple extraction process comes from the sampling clock, which is generated by the oversampling clock f ovThe sampling frequency is obtained by reducing the frequency by 2048 times, so the sampling frequency is f s =f ov / M=5kHz. The output result is extracted and input into the finite impulse response gain compensation filter according to the sampling frequency. The filter form is:

[0046]

[0047] Among them, x(n) is the input data sequence, y(n) is the output data sequence, N cmp is the order of the finite impulse response gain compensation filter, N cmp Take 9, h cmp (k) is the filter coefficient, k ranges from 0 to 8 filter coefficient h cmp (k) are: 0.001299248657, -0.01282067554, 0.07066814073, -0.3129967511, 1.507702125, -0.3129967511, 0.07066814073, -0.01282067554, 0.001299248657.

[0048] Finally, in order to achieve the measurement of effective signals, the present invention obtains the instantaneous product signal q s Take every N sampling points for truncated averaging, and multiply the result of the truncated averaging by the inverse of the proportional coefficient 1 / K, that is, multiply it by 2 to obtain the average product signal q m , average product signal q m Then calculate the measured effective value R by square root m In this embodiment, the number of sampling points N=2000.

[0049] In order to further verify the effect of the present invention, a simulation test environment was built based on MATLAB to conduct simulation tests on the present invention. The broadband communication signal S IN The amplitude-frequency characteristic curve is as follows Figure 4As shown in the figure, the signal consists of 1 kHz and 31 frequency components at 4096 Hz intervals from 304096 Hz to 426976 Hz. The amplitude of each frequency component is 0.1, and the phases are: -171.1°, 135.5°, 110.1°, -174.2°, -11.6°, -172.4°, 125.8°, -72°, -29.6°, 109.1°, and 177. 5°,36.6°,-171.7°,8.1°,-60.7°,99.3°,147.7°,50.3°,17.8°,-57.3°,-37.1°,-29.5°,-8.2°,-41.7°,-146.5°,-121.1°,77.1°,-131.6°,176.6°,-55.3°,40°,129.6°. Simulated input broadband communication signal S IN OFDM modulation signals can be simulated in the frequency band from 300k to 427kHz. IN The theoretical effective value of the signal is 0.4. The signal is output by the calculation method of the present invention 100 times the effective value of the measurement R m The average value is 0.398437, the error is -0.391%, and the statistical histogram of the error of 100 measurements is as follows Figure 5 According to the simulation results, the error of the effective value measurement of the broadband communication signal obtained by the embodiment of the present invention is relatively low.

[0050] System Example:

[0051] like Figure 6 As shown, the present invention also provides a broadband communication signal effective value measurement device, comprising a memory, a processor, and an internal bus. The processor and memory exchange data and communications with each other via the internal bus. The processor can be a microprocessor (MCU), a programmable logic device (FPGA), or other processing device. The memory can be any type of memory that stores information electrically, such as RAM and ROM; any type of memory that stores information magnetically, such as hard disks, floppy disks, magnetic tapes, magnetic core memories, bubble memories, and USB flash drives; any type of memory that stores information optically, such as CDs and DVDs; and other types of memory, such as quantum memories and graphene memories.

Claims

1. A method for measuring the effective value of a broadband communication signal, characterized in that: The steps include: 1) Splitting a broadband communication signal into two paths, oversampling and modulating the first path signal according to a first oversampling clock to obtain a first data stream; first proportionally adjusting the second path signal, and then oversampling and modulating the second path signal according to a second oversampling clock to obtain a second data stream; The frequency of the first oversampling clock is different from the frequency of the second oversampling clock, and the first data stream and the second data stream are both 1-bit data streams; 2) Performing digital filtering on the product of the first data stream and the second data stream to obtain an instantaneous product signal, and determining the effective value of the broadband communication signal based on the instantaneous product signal.

2. The broadband communication signal effective value measurement method according to claim 1, characterized in that: The adjustment coefficient K of the proportional adjustment is less than 1 and not less than 0.5; the effective value of the broadband communication signal is determined after the instantaneous product signal is multiplied by the inverse of the adjustment coefficient K.

3. The broadband communication signal effective value measurement method according to claim 2, characterized in that: The ratio of the frequency of the first sampling clock to the frequency of the second sampling clock is P, where P is an integer greater than 1.

4. The method for measuring the effective value of a broadband communication signal according to any one of claims 1 to 3, wherein: The digital filtering process in step 2) includes integral comb filtering, filtering extraction and finite impulse response gain compensation filtering.

5. The broadband communication signal effective value measurement method according to claim 4, characterized in that: The transfer function of the integral comb filter is: Wherein, G is the index of the integral comb filter, D is the delay factor, and M is the ratio of the sampling frequency of the first-pass oversampling modulation to the filter extraction clock frequency.

6. The method for measuring the effective value of a broadband communication signal according to claim 4, wherein: The transfer function of the finite impulse response gain compensation filter is: Among them, x(n) is the input data sequence, y(n) is the output data sequence, N cmp is the order of the FIR gain compensation filter.

7. The method for measuring the effective value of a broadband communication signal according to any one of claims 1 to 3, wherein: In step 1), the oversampling modulation of the first signal and the second signal both adopts a second-order oversampling modulator, and the second-order oversampling modulator is a second-order Σ-Δ oversampling modulator.

8. The method for measuring the effective value of a broadband communication signal according to any one of claims 1 to 3, wherein: The method further includes performing analog low-pass filtering on the broadband signal before dividing the broadband signal into two paths, wherein the analog low-pass filtering adopts a second-order Butterworth low-pass filter.

9. The method for measuring the effective value of a broadband communication signal according to claim 1, wherein: The effective value of the broadband communication signal is obtained by averaging the instantaneous product signal and then taking the square root.

10. A broadband communication signal effective value measurement system, characterized in that: The invention comprises a processor and a memory, wherein the processor adopts the broadband communication signal effective value measurement method according to any one of claims 1 to 9.

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