CN113852384A - Method for enhancing signal-to-noise ratio of radio frequency signal - Google Patents
Method for enhancing signal-to-noise ratio of radio frequency signal Download PDFInfo
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Abstract
The invention relates to the technical field of signal processing, in particular to a method for enhancing the signal-to-noise ratio of a radio frequency signal, which comprises the following steps: s1, receiving radio frequency signals, and searching a specific reflector signal from a static object of the signals as a reference; s2 calculating the average phase of the pulse for k frames of the signal
And calculate
A phase difference from the reference signal at the k-th frame; s3 uses the phase difference in S3 to correct the time domain noise, and after the noise is transmitted to the edge device, it uses the cascade filterAnd outputting the radio frequency signal after denoising. The phase of the received radio frequency signal after time domain noise correction is more stable, the noise is removed by utilizing a cascade filter, the signal-to-noise ratio of the received baseband signal is improved, the noise is greatly inhibited after the signal is output after the cascade filter, and the quality of the radio frequency signal is improved.
Description
Technical Field
The invention relates to the technical field of signal processing, in particular to a method for enhancing the signal-to-noise ratio of a radio frequency signal.
Background
Human Action Recognition (HAR) plays a key role in a wide range of real-world applications, traditionally achieved through wearable sensing. Recently, in order to avoid the burden and discomfort of wearable devices, a device-less approach using Radio Frequency (RF) signals has become a promising alternative to HAR. Most of the latest plant-less methods require training a large deep neural network model in the time or frequency domain, require a large amount of memory to contain the model, and require intensive computations to infer human activity.
Thus, even with significant advances in device-less HAR, current device-less approaches are far from realistic in the real world, as the computing and storage resources owned by edge devices are limited in the real world.
The deficiencies of the existing solutions for RF-based, equipment-less approaches: (1) the narrow Wi-Fi channel bandwidth results in limited resolution to resolve the active mode; (2) preprocessing the raw signal acquired by the hardware helps remove signal noise, but important signal features including activity information may also be lost. A method for signal-to-noise ratio enhancement of a radio frequency signal is therefore presented herein.
Disclosure of Invention
Aiming at the defects of the prior art, the invention discloses a method for enhancing the signal-to-noise ratio of a radio frequency signal, which is used for solving the problems.
The invention is realized by the following technical scheme:
the invention provides a method for enhancing the signal-to-noise ratio of a radio frequency signal, which comprises the following steps:
s1, receiving radio frequency signals, and searching a specific reflector signal from a static object of the signals as a reference;
s2 calculating the average phase of the pulse for k frames of the signal
And calculate
A phase difference from the reference signal at the k-th frame;
and S3, performing time domain noise correction by using the phase difference in S2, transmitting the time domain noise correction to edge equipment, denoising by using a cascade filter, and outputting a radio frequency signal.
Further, in S1, the pulse with the largest amplitude is selected from the static objects of the rf signal as a reference.
Further, in the method, the time domain noise correction uses the phase difference to rapidly adjust the phase of each sample to reduce phase jitter.
Further, the cascade filter includes a low pass filter and a smoothing filter.
Further, the cascaded filter denoising is used for improving the signal-to-noise ratio of the received baseband signal.
Further, the low pass filter comprises a finite impulse response low pass filter with taps and a hamming window.
Further, the output of the finite impulse response low-pass filter is subjected to N-point window smoothing filtering by a smoothing filter, wherein N is a positive integer less than 26.
The invention has the beneficial effects that:
the phase of the received radio frequency signal after time domain noise correction is more stable, the noise is removed by utilizing a cascade filter, the signal-to-noise ratio of the received baseband signal is improved, the noise is greatly inhibited after the signal is output after the cascade filter, and the quality of the radio frequency signal is improved.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.
FIG. 1 is a diagram of steps of a method for signal-to-noise ratio enhancement of a radio frequency signal;
FIG. 2 is a phase diagram after time domain correction according to an embodiment of the present invention;
FIG. 3 is a diagram of a raw received baseband signal according to an embodiment of the present invention;
fig. 4 is a signal diagram after cascade filtering according to an embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Example 1
The embodiment discloses a method for enhancing the signal-to-noise ratio of a radio frequency signal as shown in fig. 1, which comprises the following steps:
s1, receiving radio frequency signals, and searching a specific reflector signal from a static object of the signals as a reference;
s2 calculating the average phase of the pulse for k frames of the signal
And calculate
A phase difference from the reference signal at the k-th frame;
and S3, performing time domain noise correction by using the phase difference in S2, transmitting the time domain noise correction to edge equipment, denoising by using a cascade filter, and outputting a radio frequency signal.
The present embodiment selects the pulse with the largest amplitude from the static objects of the radio frequency signal as a reference. Time domain noise correction uses phase differences to quickly adjust the phase of each sample to reduce phase jitter.
The cascade filter of the present embodiment includes a low-pass filter and a smoothing filter. The cascaded filter denoising is used for improving the signal-to-noise ratio of the received baseband signal. The low-pass filter comprises a finite impulse response low-pass filter with taps and a Hamming window.
In the embodiment, after the reflection of the target is received by the ultra-wideband radio and transmitted to the edge device, the radio frequency reflection is denoised by using a cascade filter.
Example 2
The embodiment discloses a radio frequency signal processing method, which needs to remove noise caused by hardware and environment before inputting data into a neural network so as to improve signal quality. Thus, radio frequency signal processing includes phase noise reduction and signal to noise ratio enhancement.
The phase noise reduction of the present embodiment aims to reduce the phase jitter Δ w (t-kT)s). To achieve this, first, the present embodiment finds a reflector signal from a static object as a reference. For example, we can select the pulse with the largest amplitude. Second, for k frames, we can calculate the average phase of the pulse
Then, the present embodiment calculates
The difference in phase with the reference signal at the k-th frame. Finally, the phase of each sample is rapidly adjusted by using the difference. It can be seen that the phase after time domain noise correction is more stable as shown in fig. 2.
In the signal-to-noise ratio enhancement of the present embodiment, the original received baseband signal is corrupted by noise, as shown in fig. 3. Noise introduces errors into the neural network model. In particular, if mishandled, random noise will be learned by the neural network model and easily over-fit.
Therefore, the embodiment utilizes a cascade filter for denoising, thereby improving the signal-to-noise ratio of the received baseband signal.
The cascade filter of the present embodiment includes a low-pass filter and a smoothing filter. First a Finite Impulse Response (FIR) low pass filter is used with 26 taps and a hamming window. The output of the FIR low pass filter is then subjected to 5-point window smoothing. Fig. 4 shows the signal output after the cascade filtering, and the noise is greatly suppressed.
Example 3
In a specific implementation level, the embodiment applies a radio frequency signal to noise ratio enhancement method to human body identification, which is specifically as follows:
receiving radio frequency signals, and searching a specific reflector signal from a signal static object as a reference;
calculating the average phase of the pulse for k frames of the signal
And calculate
A phase difference from the reference signal at the k-th frame;
and correcting time domain noise by using the middle phase difference, transmitting the time domain noise to edge equipment, denoising by using a cascade filter, and outputting a radio frequency signal.
Removing the static environment after signal processing, and detecting the human motion by adopting a standard deviation and peak value average detection algorithm;
activating a signal self-adaptive convolution neural network according to the detection result, and performing full convolution operation by adopting a depth separable convolution and a point convolution or group convolution factor to establish a lightweight signal self-adaptive CNN block;
and extracting features from the spectrogram of time and frequency of the radio frequency signal by using separated branches in the CNN block, applying the features to the HAR, and deducing to obtain a human body motion result.
The phase of the received radio frequency signal after time domain noise correction is more stable, the noise is removed by using a cascade filter, the signal to noise ratio of the received baseband signal is improved, and the information extracted from the radio frequency signal can be utilized to the maximum extent, so that the accuracy of action identification is improved.
In summary, the phase of the received radio frequency signal after time domain noise correction is more stable, the signal to noise ratio of the received baseband signal is improved by using a cascade filter for denoising, the noise is greatly suppressed by the signal output after the cascade filter, and the quality of the radio frequency signal is improved.
The above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.
Claims (7)
1. A method for signal-to-noise ratio enhancement of a radio frequency signal, said method comprising the steps of:
s1, receiving radio frequency signals, and searching a specific reflector signal from a static object of the signals as a reference;
s2 calculating the average phase of the pulse for k frames of the signal
And calculate
A phase difference from the reference signal at the k-th frame;
and S3, performing time domain noise correction by using the phase difference in S2, transmitting the time domain noise correction to edge equipment, denoising by using a cascade filter, and outputting a radio frequency signal.
2. The method of claim 1, wherein in step S1, the pulse with the largest amplitude is selected from the static objects of the rf signal as a reference.
3. The method of claim 1, wherein the time domain noise correction uses the phase difference to rapidly adjust the phase of each sample to reduce phase jitter.
4. The method of claim 1, wherein the cascade filter comprises a low pass filter and a smoothing filter.
5. The method as claimed in claim 4, wherein said cascaded filter denoising is used to improve the signal-to-noise ratio of the received baseband signal.
6. The method of claim 5, wherein the low pass filter comprises a finite impulse response low pass filter with taps and Hamming windows.
7. The method of claim 5, wherein the output of the FIR low-pass filter is N-point window smoothed by a smoothing filter, wherein N is a positive integer less than 26.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN117315886A (en) * | 2023-09-07 | 2023-12-29 | 安徽建筑大学 | UWB radar-based method and device for detecting impending falling of personnel |
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- 2021-09-27 CN CN202111138352.XA patent/CN113852384A/en active Pending
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| CN1677876A (en) * | 2004-03-31 | 2005-10-05 | 清华大学 | Method and system for removing phase noise in a time-domain synchronous OFDM receiver |
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Cited By (2)
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| CN117315886B (en) * | 2023-09-07 | 2024-04-12 | 安徽建筑大学 | UWB radar-based method and device for detecting impending falling of personnel |
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