CN103439686A - Single-channel radio direction finding system - Google Patents

Abstract

The invention discloses a single-channel radio direction finding system, which includes an antenna array, a single-pole double-throw radio frequency switch module, a receiving radio frequency channel, a spectrum analysis module, a control module and an output display module. The antenna array and the single-pole double-throw radio frequency switch module The single pole double throw radio frequency switch module is connected with the receiving radio frequency channel, the receiving radio frequency channel is connected with the spectrum analysis module, the spectrum analysis module is connected with the control module, and the control module is respectively connected with the single pole double throw The radio frequency switch module is connected with the output display module. Aiming at the problem of radio direction finding in communication and military applications, the invention adopts a periodically switched antenna array controlled by a high-speed radio frequency switch, and realizes the measurement of radio incident direction by analyzing the spectrum components of received radio signals. The invention is suitable for fast radio direction finding requiring low hardware complexity and low cost.

Description

Single Channel Radio Direction Finding System

technical field

The invention relates to the technical field of antenna engineering, in particular to a single-channel radio direction-finding system for realizing radio direction-finding by using a single radio frequency channel. the

Background technique

Traditional radio direction-finding technology generally consists of antenna arrays, multi-channel receivers and controllers, and output display modules, such as phase interferometers, and direction-finding arrays based on super-resolution spatial spectrum estimation. Compared with the single-channel direction-finding system, the direction-finding system with multiple radio frequency channels has the disadvantages of complex hardware structure and high cost. At the same time, the amplitude and phase consistency of each radio frequency channel is required to be better, and additional correction equipment is required. Chinese patent "A single-channel radiolocation and direction-finding system and its direction-finding method" (patent application number: 201010598996.2) proposes a single-channel direction-finding method, which uses a switch to switch between antenna units distributed around the circumference. The phase relationship of radio signals received on adjacent antenna units is used to perform direction finding, but this direction finding method requires only one radio signal to be incident in a direction finding cycle. When multiple radio signals are incident at the same time, the resulting phase relationship is confused, causing direction finding failure. the

Contents of the invention

Aiming at the above-mentioned deficiencies in the prior art, the present invention provides a single-channel radio direction-finding system, which uses a single radio frequency channel to complete rapid direction-finding of radio signals. the

The present invention is achieved through the following technical solutions. the

A single-channel radio direction finding system, comprising an antenna array 1, a single-pole double-throw radio frequency switch module 2, a receiving radio frequency channel, a spectrum analysis module 8, a control module 9 and an output display module 10, the antenna array 1 and the single-pole double-throw radio frequency The switch module 2 is connected, the single pole double throw radio frequency switch module 2 is connected with the receiving radio frequency channel, the receiving radio frequency channel is connected with the spectrum analysis module 8, and the spectrum analysis module 8 is connected with the control module 9, the The control module 9 is connected with the single pole double throw radio frequency switch module 2 and the output display module 10 respectively, wherein:

- antenna array for receiving incoming radio signals;

-Single pole double throw radio frequency switch module, used to periodically select the radio signal received by the antenna array and feed it into the receive radio frequency channel;

-Receive the radio frequency channel, amplify the received radio signal with low noise, down-convert it to an intermediate frequency signal and suppress the generated high frequency component to obtain an analog intermediate frequency signal, and then convert the analog intermediate frequency signal into a digital signal;

- The spectrum analysis module estimates the fundamental frequency component spectrum of the digital signal output on the receiving radio frequency channel and the first harmonic component spectrum generated by the single pole double throw radio frequency switch module in the digital domain;

- The control module controls the periodic opening and closing of the single-pole double-throw radio frequency switch module by outputting logic signals; by comparing the relative relationship between the fundamental frequency component and the frequency spectrum of the first harmonic component, the radio incidence direction is obtained;

- an output display module, the control module outputs the obtained radio incident direction information to the display module and displays it. the

Preferably, when the antenna array performs one-dimensional direction finding, two antenna units are used. the

Preferably, the single pole double throw radio frequency switch module is a single pole double throw radio frequency switch or a combination of a power divider and a single pole single throw switch. the

Preferably, the single-pole double-throw radio frequency switch module performs periodic sampling, and the radio signal fed into the receiving radio frequency channel includes not only the original spectrum components, but also various harmonic components generated with the switching frequency f _p as a cycle.

Preferably, the switching frequency f _p of the single-pole double-throw radio frequency switch module satisfies the following relationship with the bandwidth B of the receiving radio frequency channel:

_fp > 2B.

Preferably, the receiving radio frequency channel is a single radio frequency receiving channel, including a low noise amplifier 3, a local oscillator signal generation module 4, a frequency down conversion module 5, a low-pass filter module 6 and an analog-to-digital conversion module 7, wherein the low noise The amplifier 3 is connected with the single-pole double-throw radio frequency switch module 2, and the down-conversion module 5 is connected with the low-noise amplifier 3, the local oscillator signal generation module 4 and the low-pass filter module 6 respectively, and the low-pass filter module 6 is connected with the model The digital conversion module 7 is connected, and the analog-to-digital conversion module 7 is connected with the spectrum analysis module 8, wherein:

- low noise amplifier 3 for low noise amplification of received radio signals;

-Local oscillator signal generation module 4, used to generate the local oscillator signal required for down-conversion;

-down-conversion module 5, used for down-converting the received radio signal to an intermediate frequency signal;

-Low-pass filtering module 6, used for performing low-pass filtering on the down-converted signal, and filtering out the high-frequency components generated after the down-conversion module;

- an analog-to-digital conversion module 7, which converts the obtained intermediate frequency analog signal into a digital signal. the

Preferably, the spectrum analysis module uses a dedicated chip for spectrum estimation, a digital signal processor chip (DSP) or a programmable logic chip (CPLD, FPGA), and uses discrete Fourier transform (DFT) or fast Fourier transform ( FFT) method to estimate. the

Preferably, the control module controls the single-pole double-throw radio frequency switch module through a single-chip microcomputer, a digital signal processor (DSP) or a programmable logic chip (CPLD, FPGA). the

Preferably, the method for obtaining the radio incident direction by the control module is specifically:

By analyzing and comparing the relationship between the fundamental frequency component spectrum Γ ₀ and the first harmonic component spectrum Γ ₁ , the radio incidence direction θ is obtained. The specific calculation relationship is as follows:

$\mathrm{<span\; class="notranslate">\; \&theta;</span>}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; arcsin</span>}<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; \&lambda;</span>}}{\mathrm{<span\; class="notranslate">\; \&pi;D</span>}}\mathrm{<span\; class="notranslate">\; arctan</span>}\frac{\mathrm{<span\; class="notranslate">\; \&pi;</span>}{\mathrm{<span\; class="notranslate">\; \&Gamma;</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}{\mathrm{<span\; class="notranslate">\; 2</span>}{\mathrm{<span\; class="notranslate">\; \&Gamma;</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}}<span\; class="notranslate">\; )</span>$

Among them, λ is the wavelength value corresponding to the fundamental frequency component, and D is the distance between the antenna elements; when the incident signal is a broadband radio frequency signal, the fundamental frequency component of several frequency points can be selected for comparison with the first harmonic component , the angle information estimated at each frequency point is averaged as the incident direction of the broadband radio frequency signal. the

The working process of the single-channel radio direction-finding system provided by the present invention is as follows: the control unit outputs a control signal to control the single-pole double-throw radio frequency switch to periodically connect the two antenna units. The radio signals received on the two antenna units are time-sharedly fed into the low-noise amplifier module through the single-pole double-throw radio frequency switch. The high-frequency components generated therein. The output analog intermediate frequency signal is converted into a digital signal by the analog-to-digital conversion module, and then the frequency spectrum of the fundamental frequency component of the received signal and the first harmonic component generated by the switch are estimated in the digital domain by the spectrum analysis module. In the control module, the direction of the incident radio signal is obtained by comparing the relative relationship between the frequency spectrum of the fundamental frequency component and the first harmonic component. Finally, the control module outputs the estimated incident direction to the display module for display. the

When the control signal is 1, the SPDT RF switch is switched to one end, and when the control signal is 0, the SPDT RF switch is switched to the other end. It can be seen from FIG. 3 that when the switch is switched, the signal of the received wireless signal changes abruptly. The sudden change of phase is related to the incident direction of the wireless signal, and is reflected in the frequency spectrum of the output signal of the SPDT RF switch, so that the direction of the wireless signal can be estimated according to the frequency spectrum of the output signal. the

The working principle of the single-channel radio direction-finding system provided by the present invention is as follows: a single-pole double-throw radio frequency switch is used in the radio frequency front end to periodically open the channels of each antenna unit according to a specific timing sequence to realize single-channel reception of radio signals. When radio signals are incident on the antenna array from different directions, the spectrum structures of the radio signals received by a single radio frequency channel are different. By analyzing the spectrum structure of the received radio signal, the incident direction of the radio signal is estimated. the

Compared with the prior art, the present invention has the following technical characteristics:

The single-channel radio direction finding system provided by the invention has simple system structure and low cost, and can measure the incident direction of multiple irrelevant radio signals arriving at the same time and the incident angle of broadband radio signals. the

Description of drawings

Other characteristics, objects and advantages of the present invention will become more apparent by reading the detailed description of non-limiting embodiments with reference to the following drawings:

Fig. 1 is a system block diagram of the present invention;

Figure 2 is a schematic diagram of the control timing of the SPDT RF switch;

Figure 3 is a schematic diagram of the output signal under the current control sequence of the SPDT RF switch;

Figure 4 is a model diagram of a single-channel radio direction-finding system performing direction-finding on two radio signals incident from different directions;

Figure 5 is the result of direction finding of two radio signals incident from different directions by a single-channel radio direction finding system;

In the figure: 1 is the antenna array, 2 is the SPDT RF switch module, 3 is the low-noise amplifier, 4 is the local oscillator signal generation module, 5 is the down-conversion module, 6 is the low-pass filter module, and 7 is the analog-to-digital conversion module , 8 is a spectrum analysis module, 9 is a control module, and 10 is an output display module. the

Detailed ways

The following is a detailed description of the embodiments of the present invention: this embodiment is implemented on the premise of the technical solution of the present invention, and provides detailed implementation methods and specific operation processes. It should be noted that those skilled in the art can make several modifications and improvements without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. the

Please also refer to Figures 1 through 5. the

This embodiment provides a single-channel radio direction finding system, including an antenna array 1, a single-pole double-throw radio frequency switch module 2, a receiving radio frequency channel, a spectrum analysis module 8, a control module 9 and an output display module 10, the antenna array 1 Connected with the single pole double throw radio frequency switch module 2, the single pole double throw radio frequency switch module 2 is connected with the receiving radio frequency channel, and the receiving radio frequency channel is connected with the spectrum analysis module 8, and the spectrum analysis module 8 is connected with the control module 9 connected, the control module 9 is respectively connected with the single pole double throw radio frequency switch module 2 and the output display module 10, wherein:

- antenna array for receiving incoming radio signals;

-Single pole double throw radio frequency switch module, used to periodically select the radio signal received by the antenna array and feed it into the receive radio frequency channel;

-Receive the radio frequency channel, amplify the received radio signal with low noise, down-convert it to an intermediate frequency signal and suppress the generated high frequency component to obtain an analog intermediate frequency signal, and then convert the analog intermediate frequency signal into a digital signal;

- The spectrum analysis module estimates the fundamental frequency component spectrum of the digital signal output on the receiving radio frequency channel and the first harmonic component spectrum generated by the single pole double throw radio frequency switch module in the digital domain;

- The control module controls the periodic opening and closing of the single-pole double-throw radio frequency switch module by outputting logic signals; by comparing the relative relationship between the fundamental frequency component and the frequency spectrum of the first harmonic component, the radio incidence direction is obtained;

- an output display module, the control module outputs the obtained radio incident direction information to the display module and displays it. the

Further, when the antenna array performs one-dimensional direction finding, two antenna units are used. the

Further, the single-pole double-throw radio frequency switch module is a single-pole double-throw radio frequency switch or a combination of a power divider and a single-pole single-throw switch. the

Further, the single-pole double-throw radio frequency switch module performs periodic sampling, and the radio signal fed into the receiving radio frequency channel includes not only the original spectrum components, but also various harmonic components generated with the switching frequency f _p as a cycle.

Further, the switching frequency _fp of the single-pole double-throw radio frequency switch module satisfies the following relationship with the bandwidth B of the receiving radio frequency channel:

_fp > 2B.

Further, the receiving radio frequency channel is a single radio frequency receiving channel, including a low noise amplifier 3, a local oscillator signal generation module 4, a frequency down conversion module 5, a low pass filter module 6 and an analog-to-digital conversion module 7, wherein the low noise The amplifier 3 is connected with the single-pole double-throw radio frequency switch module 2, and the down-conversion module 5 is connected with the low-noise amplifier 3, the local oscillator signal generation module 4 and the low-pass filter module 6 respectively, and the low-pass filter module 6 is connected with the model The digital conversion module 7 is connected, and the analog-to-digital conversion module 7 is connected with the spectrum analysis module 8, wherein:

- low noise amplifier 3 for low noise amplification of received radio signals;

-Local oscillator signal generation module 4, used to generate the local oscillator signal required for down-conversion;

-down-conversion module 5, used for down-converting the received radio signal to an intermediate frequency signal;

-Low-pass filtering module 6, used for performing low-pass filtering on the down-converted signal, and filtering out the high-frequency components generated after the down-conversion module;

- an analog-to-digital conversion module 7, which converts the obtained intermediate frequency analog signal into a digital signal. the

Further, the spectrum analysis module uses a dedicated chip for spectrum estimation, a digital signal processor chip (DSP) or a programmable logic chip (CPLD, FPGA), and uses discrete Fourier transform (DFT) or fast Fourier transform ( FFT) method to estimate. the

Further, the control module realizes the control of the single-pole double-throw radio frequency switch module through a single-chip microcomputer, a digital signal processor (DSP) or a programmable logic chip (CPLD, FPGA). the

Further, the method for obtaining the radio incidence direction by the control module is specifically:

By analyzing and comparing the relationship between the fundamental frequency component spectrum Γ ₀ and the first harmonic component spectrum Γ ₁ , the radio incidence direction θ is obtained. The specific calculation relationship is as follows:

$\mathrm{<span\; class="notranslate">\; \&theta;</span>}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; arcsin</span>}<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; \&lambda;</span>}}{\mathrm{<span\; class="notranslate">\; \&pi;D</span>}}\mathrm{<span\; class="notranslate">\; arctan</span>}\frac{\mathrm{<span\; class="notranslate">\; \&pi;</span>}{\mathrm{<span\; class="notranslate">\; \&Gamma;</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}{\mathrm{<span\; class="notranslate">\; 2</span>}{\mathrm{<span\; class="notranslate">\; \&Gamma;</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}}<span\; class="notranslate">\; )</span>$

Among them, λ is the wavelength value corresponding to the fundamental frequency component, and D is the distance between the antenna elements; when the incident signal is a broadband radio frequency signal, the fundamental frequency component of several frequency points can be selected for comparison with the first harmonic component , the angle information estimated at each frequency point is averaged as the incident direction of the broadband radio frequency signal. the

Specifically:

- Antenna array 1 for receiving radio frequency radio signals;

- Single pole double throw radio frequency switch 2, used to switch and control the reception of radio frequency radio signals;

- low noise amplifier 3, used for low noise amplification of the received radio frequency signal;

-Local oscillator signal generation module 4, used to generate the local oscillator signal required for down-conversion;

-down-conversion module 5, used for down-converting the received radio frequency signal to an intermediate frequency signal;

-Low-pass filtering module 6, used for performing low-pass filtering on the down-converted signal, and filtering out the high-frequency signal generated after the down-converting module;

-Analog-to-digital conversion module 7 converts the analog signal after down-conversion into a digital signal;

-Spectrum analysis module 8, carries out spectrum analysis to the digital signal that analog-to-digital conversion module (7) obtains

- The control module 9 controls the state of the high-speed radio frequency switch, estimates the radio incidence direction through the spectrum information obtained by the spectrum analysis module (8), and outputs and displays it;

- Output display module 10 for displaying the estimated radio direction information. the

A radio frequency switch is used to periodically control the reception of radio signals on the antenna array 1 ; the control module 9 obtains the incident direction of radio signals by comparing the relative relationship between frequency components obtained by the spectrum analysis module 8 . the

Antenna array: used to receive incoming radio signals, when performing one-dimensional direction finding, two antenna elements are used. the

Single pole double throw radio frequency switch: used to periodically select the radio signal received by each unit of the antenna array and feed it into a single radio frequency receiving channel. Due to the periodic sampling of the RF switch, the radio signal fed into the RF channel not only includes the original spectrum components, but also generates various harmonic components with the switching frequency f _p as the cycle. In order to ensure that the sampled radio signal is not distorted, the switching frequency of the high-speed radio frequency switch and the bandwidth B of the received radio frequency signal should satisfy the following relationship:

_fp > 2B.

Receiving radio frequency channel: used to amplify the received radio signal with low noise, move the spectral components to the intermediate frequency through the down converter, and convert the obtained analog intermediate frequency signal into a digital signal through the analog-to-digital converter. As shown in FIG. 1 , the receiving channel is composed of a low noise amplifier 3 , a local oscillator signal generation module 4 , a frequency down conversion module 5 , a low-pass filter module 6 and an analog-to-digital conversion module 7 . the

Spectrum analysis module: use the discrete Fourier transform (DFT) or fast Fourier transform (FFT) method to estimate the spectral components of the intermediate frequency signal output on the receiving radio frequency channel. As shown in Figure 1, the spectrum analysis module is realized by a dedicated chip (8) for spectrum estimation. the

Control module: the control module controls the periodic opening and closing of the radio frequency switch by outputting logic signals. As shown in Figure 1, the control module is implemented by a single-chip microcomputer. The incident direction θ of the radio signal is obtained by analyzing and comparing the relationship between the spectrum Γ ₀ of the fundamental frequency component of the received signal and the spectrum Γ ₁ of the first harmonic component. The specific calculation relationship is as follows:

$\mathrm{<span\; class="notranslate">\; \&theta;</span>}<span\; class="notranslate">\; =</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; arcsin</span>}<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; \&lambda;</span>}}{\mathrm{<span\; class="notranslate">\; \&pi;D</span>}}\mathrm{<span\; class="notranslate">\; arctan</span>}\frac{\mathrm{<span\; class="notranslate">\; \&pi;</span>}{\mathrm{<span\; class="notranslate">\; \&Gamma;</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}{\mathrm{<span\; class="notranslate">\; 2</span>}{\mathrm{<span\; class="notranslate">\; \&Gamma;</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}}<span\; class="notranslate">\; )</span>$

Wherein, λ is the wavelength value corresponding to the fundamental frequency component, and D is the distance between antenna elements. When the incident signal is a broadband radio frequency signal, the fundamental frequency components of several frequency points can be selected for comparison with the first harmonic component, and the angle information estimated at each frequency point can be averaged as the incident direction of the broadband radio frequency signal. Therefore, the present invention has the ability to measure the direction of incidence of broadband radio signals. the

Output display module: the channel control module outputs the obtained radio incident direction information to the display module for display. the

The working process of the single-channel radio direction-finding system provided in this embodiment is as follows: the control unit outputs a control signal to control the single-pole double-throw radio frequency switch to periodically connect the two antenna units. The radio signals received on the two antenna units are time-sharedly fed into the low-noise amplifier module through the single-pole double-throw radio frequency switch. The high-frequency components generated therein. The output analog intermediate frequency signal is converted into a digital signal by the analog-to-digital conversion module, and then the frequency spectrum of the fundamental frequency component of the received signal and the first harmonic component generated by the switch are estimated in the digital domain by the spectrum analysis module. In the control module, the direction of the incident radio signal is obtained by comparing the relative relationship between the frequency spectrum of the fundamental frequency component and the first harmonic component. Finally, the control module outputs the estimated incident direction to the display module for display. the

Please refer to FIG. 2 and FIG. 3. FIG. 2 shows the control sequence of the SPDT RF switch and the schematic diagram of the RF signal received by the SPDT RF switch. In Figure 2, when the control signal is 1, the SPDT RF switch is switched to one end, and when the control signal is 0, the SPDT RF switch is switched to the other end. It can be seen from Figure 3 that when the switch is switched, the signal of the received wireless signal changes abruptly. The sudden change of phase is related to the incident direction of the wireless signal, and is reflected in the frequency spectrum of the output signal of the SPDT RF switch, so that the direction of the wireless signal can be estimated according to the frequency spectrum of the output signal. the

The basic principle of the present invention is to use a single-pole double-throw radio frequency switch at the radio frequency front end to periodically open the channels of each antenna unit according to a specific time sequence to realize single-channel reception of radio signals. When radio signals are incident on the antenna array from different directions, the spectrum structures of the radio signals received by a single radio frequency channel are different. By analyzing the spectrum structure of the received radio signal, the incident direction of the radio signal is estimated. the

In this example:

The SPDT RF switch module can be a SPDT RF switch, or the SPDT RF switch can be replaced by a splitter and a SPST switch;

The spectrum analysis module in Figure 1 uses a dedicated chip for spectrum estimation, a digital signal processor (DSP) for a single-chip microcomputer or a programmable logic chip (CPLD, FPGA) for estimation. the

The following uses the direction finding of two irrelevant information sources as an example for specific description. the

As shown in Fig. 4, two irrelevant signal sources are set to be incident on the antenna array in the present invention from two directions at the same time. The spacing of the antenna array is 15cm. The two sources are single-frequency signals, the amplitudes of which are both 1, and the carrier frequencies are 1GHz and 1.4GHz respectively. The angles of incidence relative to the normal to the antenna array are +40° and −20°, respectively. Set the signal-to-noise ratio (SNR) of the entire channel to be 10dB. For each switching cycle of the SPDT RF switch, 100 data points are sampled, and a total of 10 cycles are sampled. After the SPDT RF switch is periodically switched and received, the output RF signal is subjected to single-channel reception, down-conversion, mode conversion and spectrum analysis, and the incident direction of the two radio signals is calculated according to the aforementioned formula. the

As shown in FIG. 5 , the abscissa in the figure represents the angle, the diamond-shaped point with the ordinate of 1 represents the actual incident direction of the two radio signals, and the square point with the ordinate of 2 represents the estimated incident direction of the two radio signals. It can be seen that the estimation error of the first wireless signal is 0.25°, and the estimation error of the second wireless signal is 0.18°, successfully realizing the measurement of the directions of two radio signals incident from different directions. the

Specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art may make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention. the

Claims (9)

1. a single channel radio direction-finding system, it is characterized in that, comprise aerial array, the single-pole double throw RF switch module, receiving RF channel, spectrum analysis module, control module and output display module, described aerial array is connected with the single-pole double throw RF switch module, described single-pole double throw RF switch module is connected with receiving RF channel, described receiving RF channel is connected with spectrum analysis module, described spectrum analysis module is connected with control module, described control module is connected with the output display module with the single-pole double throw RF switch module respectively, wherein:

-aerial array, for receiving the radio signal of incident;

-single-pole double throw RF switch module, for the radio signal of periodically selecting aerial array to receive, and the feed-in receiving RF channel;

-receiving RF channel, carry out the radio signal of reception low noise amplification, downconvert to intermediate-freuqncy signal and suppress the high fdrequency component produced, and obtains analog if signal, then analog if signal is converted to digital signal;

-spectrum analysis module is estimated the fundamental component frequency spectrum of the digital signal exported on receiving RF channel and the frequency spectrum of harmonic component for the first time produced by the single-pole double throw RF switch module in numeric field;

-control module, control the periodicity of single-pole double throw RF switch module and open and turn-off by output logic signal; By relatively fundamental component and the relativeness of the frequency spectrum of harmonic component for the first time, obtain the radio incident direction;

-output display module, control module by the radio incident direction information output that obtains to display module and show.

2. single channel radio direction-finding system according to claim 1, is characterized in that, when described aerial array carries out the one dimension direction finding, adopts two antenna elements.

3. single channel radio direction-finding system according to claim 1, is characterized in that, described single-pole double throw RF switch module is single-pole double throw RF switch or is the combination of power splitter and single-pole single-throw switch (SPST).

4. according to the described single channel radio direction-finding system of claim 1 or 3, it is characterized in that, described single-pole double throw RF switch module is carried out periodic samples, and the radio signal of feed-in receiving RF channel not only comprises the original signal spectrum composition, also comprises with switching frequency f _peach harmonic component for the cycle generation.

5. single channel radio direction-finding system according to claim 4, is characterized in that, the switching frequency f of described single-pole double throw RF switch module _pand meet following relation between the bandwidth B of receiving RF channel:

f _p＞2B。

6. single channel radio direction-finding system according to claim 1, it is characterized in that, described receiving RF channel is injection receiving cable frequently, comprise low noise amplifier, local oscillation signal generation module, down conversion module, low-pass filtering module and analog-to-digital conversion module, wherein, described low noise amplifier is connected with the single-pole double throw RF switch module, described down conversion module respectively with low noise amplifier, local oscillation signal generation module is connected with low-pass filtering module, described low-pass filtering module is connected with analog-to-digital conversion module, described analog-to-digital conversion module is connected with spectrum analysis module, wherein:

-low noise amplifier, carry out low noise amplification for the radio signal to receiving;

-local oscillation signal generation module, the required local oscillation signal for generation of down coversion;

-down conversion module, downconvert to intermediate-freuqncy signal for the radio signal by receiving;

-low-pass filtering module, carry out low-pass filtering for the signal to after down coversion, the high fdrequency component that filtering produces after down conversion module;

-analog-to-digital conversion module, be converted to digital signal by the analog intermediate frequency signal obtained.

7. single channel radio direction-finding system according to claim 1, it is characterized in that, described spectrum analysis module is by spectrum estimation special chip, DSP chip or programmable logic chip and utilize discrete Fourier transformation or the Fast Fourier Transform (FFT) method is estimated.

8. single channel radio direction-finding system according to claim 1, is characterized in that, described control module realizes the control to the single-pole double throw RF switch module by single-chip microcomputer, digital signal processor or programmable logic chip.

9. single channel radio direction-finding system according to claim 1, is characterized in that, described control module obtains the method for radio incident direction, is specially:

By analysis and comparison fundamental component frequency spectrum Γ ₀with harmonic component frequency spectrum Γ for the first time ₁between relation, obtain radio incident direction θ, concrete calculated relationship is as follows:

$\mathrm{\&theta;}=-\arcsin \left(\frac{\mathrm{\&lambda;}}{\mathrm{\&pi;D}}\arctan \frac{\mathrm{\&pi;}{\mathrm{\&Gamma;}}_1}{2{\mathrm{\&Gamma;}}_0}\right)$

Wherein, λ is the wavelength value corresponding for fundamental component, and D is the distance between antenna element; When the signal of incident is broadband rf signal, can select the fundamental component of some frequencies and harmonic component for the first time to compare, each frequency place is estimated to the angle information obtained averages as the incident direction of broadband rf signal.

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