KR101953297B1 - Method and apparatus for improving a detection rate of frequency hopping signals - Google Patents

Abstract

According to an aspect, a method of processing a frequency hopping signal may include: generating a first signal by applying a first window having a predetermined size to a received signal; Generating a first spectrum by applying a fast Fourier transform to the first signal; Generating a second signal by applying a second window of which the first window is delayed to the received signal; Generating a second spectrum by applying a fast Fourier transform to the second signal; And detecting the frequency hopping signal using the first spectrum and the second spectrum.

Description

Method and apparatus for improving a detection rate of frequency hopping signals

A method and apparatus for improving the detection rate of a frequency hopping signal. In particular, it relates to a method and apparatus for improving the detection rate of frequency hopping signals used in military communications.

Spread Spectrum technology is widely used to securely transmit signals. Frequency spreading (Frequency Hopping) method of spreading technology is used in military communication and commercial communication.

In commercial communications, frequency hopping is used to efficiently use bandwidth with multiple users minimizing interference. In commercial communication, frequency hopping technology is used as a technology such as Bluetooth standard and WLAN standard.

In military communications, the frequency hopping technique has been studied because of its excellent anti-jamming performance. Frequency hopping technology is a communication method in which a carrier hops on various frequency channels on a wide band without using a fixed carrier to transmit information. This frequency hopping technique makes it difficult to detect and recover enemy forces on friendly transmission signals. Conversely, if the enemy transmits or receives in the form of a frequency hopping signal, it will be difficult for the allies to detect and recover them. For this reason, a method for detecting and restoring a frequency hopping signal is an important research field, and many studies have been conducted. Many studies have proposed various methods to improve the detection rate of frequency hopping signals.

A method and apparatus for improving the detection rate of a frequency hopping signal are provided. In addition, the present invention provides a computer-readable recording medium having recorded thereon a program for executing the method on a computer. The technical problem to be solved is not limited to the above technical problems, and other technical problems may exist.

According to an aspect, a method of processing a frequency hopping signal may include: generating a first signal by applying a first window having a predetermined size to a received signal; Generating a first spectrum by applying a fast Fourier transform to the first signal; Generating a second signal by applying a second window of which the first window is delayed to the received signal; Generating a second spectrum by applying a fast Fourier transform to the second signal; And detecting the frequency hopping signal using the first spectrum and the second spectrum.

In the above-described method, the size of the first window and the size of the second window are determined in consideration of the size of the fast Fourier transform.

In the above-described method, the detecting step includes outputting a sum of the peak values of each of the first spectrum and the second spectrum.

In the above-described method, the received signal includes a modulated signal using a M-ary Frequency Shift Keying (MFSK) scheme.

In the above-described method, the frequency hopping signal includes any one of a signal using a fast frequency hopping method and a signal using a slow frequency hopping method.

A computer-readable recording medium according to another aspect includes a recording medium recording a program for executing the above-described method on a computer.

According to yet another aspect, an apparatus for processing a frequency hopping signal includes: a receiving unit receiving a signal; A first signal is generated by applying a first window having a predetermined size to the received signal, a fast Fourier transform is applied to the first signal, and a first spectrum is generated. A second signal is generated by applying a second window delayed by the first window to the received signal, and a third signal is generated by applying the window having the predetermined range to the received signal. A signal processor for generating a second spectrum by applying a fast Fourier transform; And a detector configured to detect the frequency hopping signal using the first spectrum and the second spectrum.

In the above-described apparatus, the size of the first window and the size of the second window are determined in consideration of the size of the fast Fourier transform.

In the above-described apparatus, the detection unit outputs the sum of the peak values of each of the first spectrum and the second spectrum.

In the above-described apparatus, the received signal includes a modulated signal using a M-ary Frequency Shift Keying (MFSK) scheme.

In the above-described apparatus, the frequency hopping signal includes any one of a signal using a fast frequency hopping method and a signal using a slow frequency hopping method.

The present invention is effective because it can be used to basically improve the detection performance of the frequency hopping signal. Assuming that the pseudo random random pattern of the frequency hopping signal is not known, the signal is detected by an energy detection method. When creating an energy map of a signal collected in a frequency-time (FT) domain, the present invention uses windowing to increase the detection performance of the collected FFT signal. This may be applied to both a fast frequency hopping and a slow frequency hopping scheme among frequency hopping communication methods. In addition, the present invention can be effectively used even when attempting to jam the enemy signal (Jamming). It can also be applied to commercial communications such as Bluetooth to provide better quality communications.

1 is a block diagram illustrating an example of an apparatus for processing a frequency hopping signal, according to an exemplary embodiment.
2 is a diagram for describing a frequency hopping signal, according to an exemplary embodiment.
3 is a block diagram illustrating an example of an apparatus for processing a frequency hopping signal, according to an exemplary embodiment.
4 is a diagram for describing an operation of a signal processor according to an exemplary embodiment.
5 is a flowchart illustrating an example of a method of processing a frequency hopping signal, according to an exemplary embodiment.

The terminology used in the embodiments is a general term that has been widely used as much as possible in consideration of the functions of the present invention, but may vary according to the intention or precedent of a person skilled in the art, the emergence of new technology, and the like. In addition, in certain cases, there is also a term arbitrarily selected by the applicant, in which case the meaning will be described in detail in the description of the invention. Therefore, the terms used in the present invention should be defined based on the meanings of the terms and the contents throughout the present invention, rather than the names of the simple terms.

When a part of the specification is said to "include" any component, this means that it may further include other components, except to exclude other components unless otherwise stated. In addition, the “…” described in the specification. Wealth ”,“… Module ”means a unit for processing at least one function or operation, which may be implemented in hardware or software, or a combination of hardware and software.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention.

Hereinafter, with reference to the drawings will be described embodiments of the present invention;

1 is a block diagram illustrating an example of an apparatus for processing a frequency hopping signal, according to an exemplary embodiment.

Referring to FIG. 1, an apparatus 100 for processing a frequency hopping signal includes a receiver 110, a signal processor 120, and a detector 130.

The receiver 110 receives a signal from an external device. For example, the receiver 110 may be configured of an antenna (not shown) for receiving a signal, a high frequency reception circuit for amplifying, converting, etc. the received signal.

The receiver 110 may receive a frequency hopping signal. For example, the frequency hopping signal may be a signal using a fast frequency hopping method or a signal using a slow frequency hopping method.

Fast frequency hopping technology refers to the use of multiple hops per bit. On the other hand, the slow frequency hopping technique means a method of allocating several bits per hop. Specific methods of the fast frequency hopping technique and the slow frequency hopping technique are obvious to those of ordinary skill in the art, and thus detailed descriptions thereof will be omitted.

Meanwhile, the signal received by the receiver 110 may be a modulated signal using a M-ary frequency shift keying (MFSK) scheme. A specific example of the signal received by the receiver 110 will be described later with reference to FIG. 2.

2 is a diagram for describing a frequency hopping signal, according to an exemplary embodiment.

2A illustrates an example of a bit sequence representing data to be transmitted. FIG. 2B illustrates an example in which data shown in FIG. 2A is modulated by a binary frequency shift keying (BFSK) modulation scheme. In addition, FIG. 2D illustrates an example in which a signal corresponding to six frequencies shown in FIG. 2C and a signal shown in FIG. 2B are combined.

In general, in a direct spreading system, a PSK (Phase Shift Keying) method is mainly used as a modulation scheme. However, in frequency hopping systems, frequency shift keying (FSK) is mainly used as a modulation method. Meanwhile, the PN sequence is multiplied by the FH-Modulator included in the transmitter (not shown) of the signal, whereby the carrier frequency of the modulated signal is hopped pseudo-randomly. )

The frequency hopping signal generated by the above-described process may be difficult to catch an accurate signal because the carrier frequency of the signal hops at a high speed, but the power of the signal is very low (that is, Noise level), it is very difficult for a receiver to distinguish these signals from noise.

Accordingly, the signal processor 120 according to an embodiment of the present invention may improve the detection performance of the frequency hopping signal by applying the first window and the second window to the received signal.

Referring back to FIG. 1, the signal processor 120 generates a first signal by applying a first window having a predetermined size to a signal received by the receiver 110. The signal processor 120 generates a first spectrum by applying a fast Fourier transform to the first signal.

In parallel with the process of generating the first signal and the first spectrum, the signal processor 120 generates a second signal by applying a second window to the signal received by the receiver 110. Here, the second window means a window in which the first window is delayed. In other words, the second window has a starting point that is delayed by a predetermined time from the starting point of the first window. Here, the size of the first window and the size of the second window may be determined in consideration of the size of the fast Fourier transform. The signal processor 120 generates a second spectrum by applying a fast Fourier transform to the second signal.

The detector 130 detects the frequency hopping signal using the first spectrum and the second spectrum. Specifically, the detector 130 outputs the sum of the peak values of each of the first spectrum and the second spectrum.

In general, a fast Fourier Transform (FFT) receiver is used to detect a frequency hopping signal in the wide band. FFT means converting the components of the time axis into frequency components. At this time, the resolution of the frequency is determined according to the FFT point.

For example, when the FFT point is N and the sampling frequency of the signal is fs, the frequency represented by one FFT point is fs / N. For example, when fs = 0 ~ 16MHz, N = 1024, the frequency is represented every 16M / 1024 intervals. When the FFT receiver detects a frequency weak signal, it shows the best detection performance if the frequency of the detection signal exactly matches an integer multiple of fs / N. However, if the frequency of the detection signal does not exactly match an integer multiple of fs / N, spectral leakage occurs. If the frequency of the detection signal is located in the middle of the FFT point, spectral leakage occurs most severely, and this case shows the worst detection performance.

Apparatus 100 according to an embodiment of the present invention applies a window to a received signal to minimize degradation of detection performance due to spectral leakage. When a window is applied, the effect of compressing the range where spectral leakage occurs can be obtained. Conversely, however, if the frequency of the detection signal exhibits good detection performance that exactly matches the FFT signal, some performance degradation occurs by applying a window. Thus, the device 100 applies the first window and the second window to compensate for the loss of signal power due to the application of the window. In other words, the apparatus 100 applies the first window and the second window delayed by the first window to the received signal. Accordingly, the apparatus 100 exhibits improved detection performance both in the case of exactly matching the FFT point and in the case of spectral leakage due to not exactly matching the FFT point.

3, operations of the signal processor 120 and the detector 130 of the apparatus 100 will be described in detail.

3 is a block diagram illustrating an example of an apparatus for processing a frequency hopping signal, according to an exemplary embodiment.

The operation of the receiver 110 shown in FIG. 3 is as described above with reference to FIG. 1. Therefore, hereinafter, a detailed description of the receiver 110 will be omitted.

The signal processor 120 generates a first signal by applying a first window to the signal received by the receiver 110. Here, the size of the first window may be determined in consideration of the fast Fourier transform (FFT) size.

The signal processor 120 generates a first spectrum by applying a fast Fourier transform to the first signal.

The signal processor 120 sets a second window in which the first window is delayed. In other words, the signal processor 120 sets a point delayed from the start point of the first window as the start point of the second window.

For example, the signal processor 120 may determine a start point of the second window based on a delay value of a signal preprocessed by the signal processor 120 (that is, a signal previously received by the receiver 110). Depending on factors such as a different transmission path of the signal, a signal transmitted from a transmitter (not shown) may be delayed and arrive at the receiver 110. As the signal processor 120 determines the start point of the second window based on the delay value of the preprocessed signal, the detection performance of the frequency hopping signal may be further improved.

Here, the size of the first window and the size of the second window may be the same. Accordingly, the size of the second window may be determined in consideration of the fast Fourier transform (FFT) size.

The signal processor 120 generates a second signal by applying a second window to the signal received by the receiver 110. The signal processor 120 generates a second spectrum by applying a fast Fourier transform to the second signal.

Hereinafter, an example in which the signal processing unit 120 applies the first window and the second window to the signal received by the receiver 110 will be described with reference to FIG. 4.

4 is a diagram for describing an operation of a signal processor according to an exemplary embodiment.

4A illustrates an example of a signal that the receiver 110 receives. 4B illustrates an example in which the signal processing unit 120 applies the first window to the signal shown in FIG. 4A. 4C illustrates an example in which the signal processing unit 120 applies a second window to the signal shown in FIG. 4A.

Referring to FIG. 4A, a total of 512 FFT points may be provided. In this case, referring to FIGS. 4B to 4C, sizes of the first window and the second window may correspond to sizes of 127 FFT points. The start point of the second window may be set to a point delayed by a time point corresponding to 127 FFT points from the start point of the first window.

Referring back to FIG. 3, the detector 130 detects the frequency hopping signal using the first spectrum and the second spectrum. Specifically, the detector 130 outputs the sum of the peak values of each of the first spectrum and the second spectrum.

5 is a flowchart illustrating an example of a method of processing a frequency hopping signal, according to an exemplary embodiment.

Referring to FIG. 5, a method for processing a frequency hopping signal consists of steps that are processed in time series in the apparatus 100 shown in FIGS. 1 and 3. Therefore, even if omitted below, it can be seen that the above description of the apparatus 100 shown in FIGS. 1 and 3 also applies to the method of processing the frequency hopping signal of FIG. 5.

In operation 510, the signal processor 120 generates a first signal by applying a first window having a predetermined size to the signal received by the receiver 110. Here, the size of the first window may be determined in consideration of the size of the fast Fourier transform. In this case, the signal received by the receiver 110 may be a modulated signal using a M-ary frequency shift keying (MFSK) scheme.

In operation 520, the signal processor 120 generates a first spectrum by applying a fast Fourier transform to the first signal.

In operation 530, the signal processor 120 generates a second signal by applying a second window having a delayed first window to the received signal. Here, the size of the second window may also be determined in consideration of the size of the fast Fourier transform.

In operation 540, the signal processor 120 applies a fast Fourier transform to the second signal to generate a second spectrum.

In operation 550, the detector 130 detects the frequency hopping signal using the first spectrum and the second spectrum. For example, the detector 130 outputs the sum of the peak values of each of the first spectrum and the second spectrum.

It will also be appreciated that the various illustrative logical blocks, and algorithm steps described in connection with the embodiments disclosed herein, may be implemented as electronic hardware, computer software, or a combination thereof. To clearly illustrate this interchangeability of hardware and software, various illustrative components, blocks, modules, circuits, and steps have been described above generally in terms of their functionality.

Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the overall system. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of exemplary embodiments of the present invention.

Various example logic blocks described in connection with the embodiments disclosed herein may be a general purpose processor, digital signal processor (DSP), application specific integrated circuit (ASIC), field programmable gate array (FPGA) or other programmable logic device, Discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein may be implemented or performed.

A general purpose processor may be a microprocessor, but in the alternative, the processor may be any conventional processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices, eg, a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration.

The steps of a method or algorithm described in connection with the embodiments disclosed herein may be implemented directly in hardware, in a software module executed by a processor, or in a combination thereof. The software module may include random access memory (RAM), flash memory, read only memory (ROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM), registers, hard disk, removable disk, It may reside on a CD-ROM or any other form of storage medium known in the art. An exemplary storage medium is coupled to the processor such that the processor can read information from and write information to the storage medium.

In the alternative, the storage medium may be integral to the processor. The processor and the storage medium may reside in an ASIC. The ASIC may reside in a user terminal. In the alternative, the processor and the storage medium may reside as discrete components in a user terminal.

In one or more illustrative embodiments, the functions described may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, the functions may be stored or transmitted as one or more instructions or code on a computer-readable medium. Computer-readable media includes computer storage media. A storage medium may be any available medium that can be accessed by a computer. By way of example, and not limitation, such computer-readable media may be desired in the form of RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or instructions or data structures. It can include any other medium that can be used to carry or store the program code and can be accessed by a computer.

Also, any connection is properly termed a computer-readable medium. For example, if software is transmitted from a website, server, or other remote source using coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL), or wireless technologies such as infrared, wireless, and microwave, the coaxial Cables, fiber optic cables, twisted pairs, DSL, or wireless technologies such as infrared, wireless and microwave are included within the definition of the medium. As used herein, disks and disks include compact disks (CDs), laser disks, optical disks, digital versatile discs (DVDs), floppy disks, and Blu-ray disks, where: Disks generally magnetically reproduce data, but discs optically reproduce data using lasers. Combinations of the above should also be included within the scope of computer-readable media.

The previous description of the disclosed exemplary embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these exemplary embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments described herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

100: device
110: receiver
120: signal processing unit
130: detector

Claims (11)

A method of processing a frequency hopping signal,
Generating a first signal by applying a first window having a predetermined size to the received signal;
Generating a first spectrum by applying a fast Fourier transform to the first signal;
Generating a second signal by applying a second window of which the first window is delayed to the received signal;
Generating a second spectrum by applying a fast Fourier transform to the second signal; And
Detecting the frequency hopping signal using the first spectrum and the second spectrum;
The start time of the second window is determined according to the delay value of the previously received signal, the size of the second window is the same as the size of the first window,
Generating the first signal and generating the first spectrum, generating the second signal and generating the second spectrum are performed in parallel. The method of claim 1,
The size of the first window and the size of the second window are determined in consideration of the size of the fast Fourier transform. The method of claim 1,
The detecting step,
Outputting a sum of the peak values of each of the first spectrum and the second spectrum. The method of claim 1,
The received signal includes a modulated signal using M-ary frequency shift keying (MFSK). The method of claim 1,
The frequency hopping signal is one of a signal using a fast frequency hopping method and a signal using a slow frequency hopping method. A computer-readable recording medium having recorded thereon a program for executing the method of claim 1 on a computer. An apparatus for processing a frequency hopping signal,
Receiving unit for receiving a signal;
A first signal is generated by applying a first window having a predetermined size to the received signal, a fast Fourier transform is applied to the first signal, and a first spectrum is generated. A second signal is generated by applying a second window delayed by the first window to the received signal, and a third signal is generated by applying the window having the predetermined range to the received signal. A signal processor for generating a second spectrum by applying a fast Fourier transform; And
And a detector configured to detect the frequency hopping signal using the first spectrum and the second spectrum.
The start time of the second window is determined according to a delay value of a signal previously received by the receiver, and the size of the second window is equal to the size of the first window.
And the signal processor is configured to perform the step of generating the first signal and the step of generating the first spectrum in parallel with the step of generating the second signal and the step of generating the second spectrum. The method of claim 7, wherein
The size of the first window and the size of the second window are determined in consideration of the size of the fast Fourier transform. The method of claim 7, wherein
The detection unit,
And outputting the sum of the peak values of each of the first spectrum and the second spectrum. The method of claim 7, wherein
The received signal includes a signal modulated by M-ary frequency shift keying (MFSK). The method of claim 7, wherein
The frequency hopping signal is one of a signal using a fast frequency hopping method and a signal using a slow frequency hopping method.

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