A simple signal interference detection method

Abstract

The present application relates to a simple signal interference detection method, which adopts signal statistics method, no longer uses energy as the discrimination basis, obtains N-bit digital signal S through A / D conversion, and respectively calculates zero-mean N-bit digital signal S0 and standard deviation sigma, compares the size of S0 and sigma, when S0<=sigma, then the counter k is added by 1, and omega is calculated, through judging the relationship between omega and 0.6826, whether the received space signal is normal and whether there is interference signal in the space can be effectively detected, the signal interference detection method of the present application overcomes the false alarm problem of interference detection when the energy of useful signal is large, and also overcomes the interference detection failure problem when the interference energy is small, and the process is simple and convenient to operate, which greatly reduces the complexity of signal interference detection.

Description

Technical Field

[0001] This invention relates to a simple signal interference detection method, applicable to various types of receivers such as weapon models, ground stations, spaceborne, and rocket-borne receivers. Background Technology

[0002] Currently, interference detection uses the energy detection method. Generally, the energy of actual satellite signals in space is very low. Traditional methods assess the energy of the received signal; if the energy is high, it is considered an interference signal. However, this method uses a relatively simple discrimination mechanism, and under ideal conditions, the energy detection method can effectively identify interference signals. But in real-world environments, the electromagnetic environment in space is extremely complex, with signals of various frequencies, power levels, and standards. Using the energy method for identification is no longer sufficient for practical applications. Furthermore, during system integration testing, satellite signal simulators are used to test and verify receivers. When the simulator signal power is amplified, using the energy method to identify interference will result in false alarms. In some real-world environments, satellite signals are extremely weak, approaching the receiver's sensitivity specifications. In such cases, even low-power interference can cause the receiver to malfunction. In the energy detection method, the received signal energy is not high, but interference is still present and causes the receiver to malfunction; this method cannot effectively identify interference signals. Due to its limitations, the energy detection method is not ideal in practical applications. Summary of the Invention

[0003] The purpose of this invention is to overcome the above-mentioned shortcomings of the prior art and provide a simple interference detection method. This method overcomes the problem of false alarms in interference detection when the useful signal energy is large, and also overcomes the problem of interference detection failure when the interference energy is small. It can effectively detect whether the received spatial signal is normal and whether there is interference signal in the space.

[0004] The above-mentioned objective of the present invention is achieved through the following technical solution:

[0005] A simple method for detecting signal interference includes the following steps:

[0006] (1) Perform A / D conversion on the received analog signal to obtain an N-bit digital signal S;

[0007] (2) Calculate the moving average U of the obtained N-bit digital signal and subtract the value of U from the signal S to obtain the N-bit digital signal S0 with zero mean;

[0008] (3) Squaring S0 gives S0 2 Then find S0 2 moving average And simultaneously calculate the moving average of S0. square

[0009] (4) Use minus Obtain the variance value σ of the signal. 2 ;

[0010] (5) The difference between the two sides σ 2 Take the square root to obtain the standard deviation σ;

[0011] (6) Within each time interval T, count M S0 values. When |S0|≤σ, increment the counter k by 1 and calculate... The initial value of k is 0. If ω fluctuates around 0.6826, the signal is considered normal. If ω deviates significantly from 0.6826, the signal is considered to be interfered with. The greater the deviation, the higher the proportion of interference signal.

[0012] Where N and M are both positive integers.

[0013] In the above simple signal interference detection method, if ω fluctuates within the range of 0.6826±1% in step (6), the signal can be considered normal; if ω fluctuates outside the range of 0.6826±1%, interference can be considered to exist.

[0014] In the above simple signal interference detection method, the time period T in step (6) is 10 milliseconds to 5 seconds.

[0015] The beneficial effects of this invention compared to the prior art are as follows:

[0016] (1) The signal interference detection method of the present invention adopts the signal statistics method, no longer using energy as the basis for identification. The zero-mean N-bit digital signal S0 and standard deviation σ are calculated respectively. The magnitudes of S0 and σ are compared and ω is calculated. By judging the relationship between ω and 0.6826, it is possible to effectively detect whether the received spatial signal is normal and whether there is interference signal in the space. The signal interference detection method of the present invention overcomes the problem of false alarm of interference detection when the useful signal energy is large, and also overcomes the problem of interference detection failure when the interference energy is small.

[0017] (2) The signal interference detection method of the present invention can effectively identify interference signals in actual environments, regardless of how complex the electromagnetic environment is, and has strong versatility.

[0018] (3) During the system connection test, when the simulator is used, the signal power is amplified in the signal interference detection method of the present invention, which will not produce false alarm interference and improves the accuracy of signal interference detection.

[0019] (4) The signal interference detection method of the present invention is simple in process and easy to operate, which greatly reduces the complexity of signal interference detection. It can be used as an effective basis for analyzing the electromagnetic environment of the system during system joint testing and has strong practicality.

[0020] (5) The signal interference detection method of the present invention can be applied to various types of receivers such as weapon models, ground stations, spaceborne, and rocket-borne receivers. It can effectively detect whether the received space signal is normal and whether there is interference signal in space, and has a very wide range of applications. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the system structure used in the signal interference detection method of the present invention. Detailed Implementation

[0022] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments:

[0023] The signal interference detection method of the present invention performs A / D conversion on the received analog signal to obtain a digital signal, quantizes the digital signal, performs mathematical statistics on the quantized digital signal, and finally identifies whether interference exists based on the statistical values.

[0024] In modern communication, useful signals are transmitted embedded in noise. Therefore, the normal signal received by the receiver should be white noise with a normal amplitude distribution. Based on the normal amplitude distribution of the received signal, the confidence level for an amplitude not exceeding one standard deviation of the amplitude is 0.6826. When the signal is normal, its statistical parameters should fluctuate slightly around 0.6826. However, when interference is present, because the amplitude, frequency, and mode of the interference signal are completely different from the noise, it will change the signal's parameter characteristics; that is, the received signal will no longer exhibit a normal amplitude distribution. The statistical parameters will then deviate significantly from 0.6826. By identifying these statistical parameters, the presence of interference signals can be effectively determined.

[0025] The specific process of the signal interference detection method of the present invention is as follows:

[0026] Step (1): Perform A / D conversion on the received analog signal to obtain an N-bit digital signal S;

[0027] Step (2): Calculate the moving average U of the obtained N-bit digital signal and subtract the value of U from the signal S to obtain the N-bit digital signal S0 with zero mean;

[0028] Step (3): Squaring S0 gives S0 2 Then find S0 2 moving average And simultaneously calculate the moving average of S0. square

[0029] Step (4), using minus Obtain the variance value σ of the signal. 2 ;

[0030] Step (5), the difference σ between the two sides 2 Take the square root to obtain the standard deviation σ;

[0031] Step (6): Within each time interval T, count M S0 values. When |S0|≤σ, increment the counter k by 1 and calculate... If ω fluctuates around 0.6826, i.e., within the range of 0.6826 ± 1%, the signal is considered normal. If ω deviates significantly from 0.6826, i.e., fluctuates outside the range of 0.6826 ± 1%, interference is considered to exist in the signal. The greater the deviation, the higher the proportion of interference signal. The initial value of counter k is 0, and ω is the proportion of M sampled values ​​S0 whose absolute value is less than or equal to one times σ. N is the number of bits converted by the A / D converter, and M is the sampling frequency of the A / D converter.

[0032] The T time period is typically 10 milliseconds to 5 seconds.

[0033] like Figure 1 The figure shows a schematic diagram of the system structure used in the signal interference detection method of the present invention. As can be seen from the figure, the system consists of an A / D converter, a DC removal module, a standard deviation calculation module, a quantization module, and a statistical module.

[0034] Example 1

[0035] (1) An 8-bit A / D converter is used to convert the analog signal into an 8-bit digital signal S. The 8-bit digital signal S enters the DC removal module implemented by FPGA programming. The DC removal module uses a moving average method to obtain the expected mean U. Then, the expected mean U is subtracted from the original 8-bit signal S to obtain a digital signal S0 with a mean of zero.

[0036] (2) After obtaining the digital signal S0 with a mean of zero, it is sent to the standard deviation module implemented by FPGA programming to obtain the standard deviation σ of the digital signal.

[0037] (3) After obtaining the standard deviation σ, the digital signal S0 with a mean of zero and the standard deviation σ are simultaneously sent to the quantization module implemented by the FPGA programming. In the quantization module, the signal is classified as follows: when the digital signal S0 > 1 times the standard deviation σ, a two-bit binary number 11 is output; when 0 < the digital signal S0 < 1 times the standard deviation σ, a two-bit binary number 10 is output; when -1 times the standard deviation σ < the digital signal S0 < 0, a two-bit binary number 01 is output; when the digital signal S0 < -1 times the standard deviation σ, a two-bit binary number 00 is output.

[0038] (4) In the statistical module implemented by FPGA programming, 40M digital signal samples can be obtained by calculating a time period of 1 second and an A / D sampling frequency of 40MHz. The number of 11, 10, 01, and 00 samples k1, k2, k3, and k4 are counted within this 1 second, where 10 and 01 (K2 and k3) meet the requirements.

[0039] (5) Calculate ω=(k2+k3) / 40M. If ω fluctuates within the range of 0.6826±1%, it is considered that there is no interference. If ω fluctuates outside the range of 0.6826±1%, that is, deviates from the range of 0.6826±1%, it is considered that there is signal interference.

[0040] The above description is only the best specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the protection scope of the present invention.

[0041] The contents not described in detail in this specification are common knowledge to those skilled in the art.

Claims

1. A simple method for detecting signal interference, characterized in that... Includes the following steps: (1) Perform A / D conversion on the received analog signal to obtain an N-bit digital signal S; (2) Calculate the moving average U of the obtained N-bit digital signal S, and subtract the value of U from the N-bit digital signal S to obtain the N-bit digital signal S0 with zero mean; (3) Squaring S0 gives S0 2 Then find S0 2 moving average And simultaneously calculate the moving average of S0. square (4) Use minus Obtain the variance value σ of the signal. 2 ; (5) The difference between the two sides σ 2 Take the square root to obtain the standard deviation σ; (6) Within each time interval T, count M S0 values. When |S0|≤σ, increment the counter k by 1 and calculate... The initial value of k is 0. If ω fluctuates within the range of 0.6826±1%, the signal is considered normal. If ω fluctuates outside the range of 0.6826±1%, the signal is considered to be interfered with. The more severe the deviation, the higher the proportion of interference signal. Where N and M are both positive integers.

2. The simple signal interference detection method according to claim 1, characterized in that: The time period T in step (6) is 10 milliseconds to 5 seconds.

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