KR101164853B1 - Signal processing method and system - Google Patents

Abstract

The present invention relates to a signal processing method and system. The signal processing system of the present invention includes a reception antenna for receiving a wireless signal, an all-optical converter for converting a wireless signal into an optical signal, an optical fiber for transmitting an optical signal, and an optical signal transmitted through the optical fiber to a wireless signal. It includes a photoelectric conversion unit. According to the present invention, it is possible to reduce the volume or weight compared to the prior art, a simpler system configuration is possible, and there is an advantage in terms of cost.

Wireless signal, Signal processing, Antenna, Optical signal, Optical fiber, Optical conversion, Photoelectric conversion

Description

Signal processing method and system {SIGNAL PROCESSING METHOD AND SYSTEM}

The present invention relates to a signal processing method and system.

The present invention is derived from the research conducted as part of the Ministry of Knowledge Economy's information and communication standard development support project [Task Management Number: 2008-P1-30-06F82, Task name: Development of broadband RF antenna measurement technology standard].

When measuring radio signals to analyze antenna characteristics, electromagnetic compatibility (EMC), effective radiated power (ERP), and effective isotropic radiated power (EIRP), a radio frequency (RF) cable connected to the receiving antenna affects electromagnetic waves. Because of the madness, there is a problem that accurate measurement is difficult. The reason why the RF cable affects electromagnetic waves is that the RF cable acts as a secondary radiator due to the current generated in the shielded outer surface of the RF cable. In general, the antenna is rotated when measuring the characteristics of the antenna. However, when the antenna rotates, the cable connected to the antenna moves together, and an error occurs in the measurement result as the cable moves. In particular, when the vertically polarized antenna moves vertically connected cable, the error of the measurement result is quite large, and there is a research result that this error can be 7dB to 10dB.

Several techniques are known for minimizing the effects of RF cable in wireless signal measurement. One of the most used methods is the use of ferrite beads (Ferrite Bead). Using ferrite beads minimizes the current drawn in the RF cable, and this method is effective in reducing the error in measurement results caused by the RF cable. However, ferrite beads are generally effective in the frequency band of several MHz to several hundred MHz, but do not operate well in the frequency band above GHz. Another technique for reducing the impact of RF cables is to mount a quarter-wave sleeve balun on the RF cable. However, since the balun has a structurally limited bandwidth, this method also has a problem that it is effective only in a limited frequency band. In addition, coaxial lines used in ferrite beads or baluns also increase the weight of the overall system and the complexity of the system configuration.

On the other hand, the wireless signal measurement in the outside site is more diverse than the wireless signal measurement in the room such as the FAC (Fully Anechoic Chamber), the Semi-Anechoic Chamber (SAC), and the Open Site (OS). Consider environmental factors. For example, it is difficult to make accurate measurements of radio signals due to various interference sources (e.g. trees, buildings, etc.) other than the ones to be measured. This problem results in a more complex structure of the signal measurement system. The distance between the signal source to be measured and the signal measurement system is also important, because the distance can vary many factors that indicate the distribution of the electromagnetic field, the gain of the antenna, and the output of other antennas and wireless devices. Also, the height from the ground of the signal measurement system should be considered to reduce measurement errors due to reflections and diffraction from external buildings or ground.

Therefore, the present invention can always display the same characteristics regardless of the frequency of the signal in the processing of the radio signal, in particular the signal processing method and system that can prevent secondary radiation phenomena due to the use of conventional RF cable To provide a purpose.

In another aspect, the present invention is to provide a signal processing method and system that can reduce the volume or weight, a simpler configuration, and lower cost compared to the prior art.

The objects of the present invention are not limited to the above-mentioned objects, and other objects and advantages of the present invention, which are not mentioned above, can be understood by the following description, and more clearly by the embodiments of the present invention. It will also be readily apparent that the objects and advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims.

The present invention for achieving the object of the present invention, in the signal processing system, a receiving antenna for receiving a wireless signal, an all-optical conversion unit for converting a wireless signal into an optical signal, an optical fiber for transmitting the optical signal and the optical fiber transmitted through the optical fiber It characterized in that it comprises a photoelectric conversion unit for converting the signal into a wireless signal.

The present invention also provides a signal processing method comprising the steps of: receiving a wireless signal, converting a wireless signal into an optical signal, transmitting an optical signal through the optical fiber, and converting the optical signal transmitted through the optical fiber into a wireless signal It is another feature that includes the step of converting.

According to the present invention as described above, it is possible to always display the same characteristics irrespective of the frequency of the signal in the processing of the radio signal, in particular, it is possible to prevent secondary radiation phenomena due to the use of conventional RF cable There is an advantage.

In addition, according to the present invention it is possible to reduce the volume or weight compared to the prior art, it is possible to simplify the system configuration, there is an advantage in terms of cost.

The above objects, features, and advantages will be described in detail with reference to the accompanying drawings, and thus, those skilled in the art may easily implement the technical idea of the present invention. In describing the present invention, when it is determined that the detailed description of the known technology related to the present invention may unnecessarily obscure the gist of the present invention, the detailed description will be omitted. Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the drawings, the same reference numerals are used to indicate the same or similar components.

1 is a diagram illustrating a wireless signal measuring system and a field signal measuring environment to which a signal processing method according to the present invention can be applied.

Compared to wireless signal measurement in the room such as an anechoic chamber (FAC: Fully Anechoic Chamber), a semi-anechoic chamber (SAC), and an open site (OS: Open Site), wireless signal measurement in an external site as shown in FIG. Should take additional environmental factors into account. First, as shown in FIG. 1, a signal measurement system for measuring a radio signal 116 and a signal source 114 for generating a radio signal 116 (eg, a base station or relay station of a mobile communication system or broadcast system). There may be houses, factories, trees, cars, and the like between 102 and 112. Since such interfering signal sources between the signal source 114 and the signal measuring systems 102 to 112 cause a decrease in the accuracy of the measurement in the measurement of the radio signal, consideration for such an interfering signal source in the measurement of the radio signal Is needed.

On the other hand, the distance from the signal source 114 is also a factor in wireless signal measurement in the field. Typically, a signal source 114, such as a base station, will copy a radio signal 116, such as an RF signal, for communication or broadcast service in its service area. In this case, in order to provide a service for a sufficiently large area, the signal source 114 is mainly disposed at a height higher than a certain level from the ground, such as the pylon 118. The radiant energy of the radio signal 116 radiated from this signal source 114 is reduced as a function of distance.

Measurement of the radio signal 116, such as electromagnetic waves, may be made in the near-field, the Fresnel zone, the far-field, and the like. When measuring the gain of an antenna or the strength of a signal, it is important whether this measurement is made in the near field or in the far field. This is because various factors representing the output of the antenna and the wireless device, such as the distribution of the electromagnetic field and the gain, vary depending on the distance of the measurement point from the transmitting antenna 114 generating the wireless signal.

When the distance between the signal source 114 and the signal measurement systems 102 to 112 is sufficiently far apart, the antenna gain or signal strength at the signal measurement point becomes a constant value, which is the gain of the antenna generally referred to. Or a stable propagation intensity that calculates the effective radiant output. When the size of the antenna is D, even if the gain is measured at a distance that satisfies Rayleigh's well-known far-field formula (Equation 1), an error of about 0.5 dB occurs. Therefore, to reduce the measurement error, it is necessary to measure at a much longer distance than this.

In order to reduce the error according to the interference signal source and the measurement distance, it is necessary for the signal measuring systems 102 to 112 to secure a sufficient distance from the signal source 114, and also to at least a height corresponding to the signal source 114 from the ground. Should be secured.

The signal processing method according to the present invention reflects such considerations, and the signal measuring systems 102 to 112 shown in FIG. 1 are applied to the signal processing method according to the present invention. As shown in FIG. 1, the signal measurement systems 102-112 include a receiving antenna 102, a mast 104, an optical cable 106, a support 108 for supporting the master, and a height for adjusting the mast height. The motor 110 includes a mobile vehicle 112. In the case of using the signal measuring systems 102 to 112, the adjustment of the height of the mast 104 through the motor 110 and the mounting of the mobile vehicle 112 also enable the desired distance adjustment.

On the other hand, according to the prior art, the radio signal 116 copied from the signal source 114 is input to the receiving antenna 102 through a free space of a predetermined distance. The input wireless signal 116 is then transmitted to a signal analysis system, for example a spectrum analyzer, via a conventional RF cable, and the signal analysis system detects the reception level of the transmitted wireless signal 116. The conventional signal measuring system using the RF cable has the disadvantage of being able to use only in a limited bandwidth, causing secondary radiation by the RF cable, and increasing the overall system complexity and weight. .

The signal measuring system 102 to 112 of FIG. 1 to which the signal processing method according to the present invention and the signal processing method according to the present invention are applied are intended to solve this disadvantage. The wireless signal 116 received by the receiving antenna 102 is converted into an optical signal by an all-optical conversion module used instead of a commercial RF cable, and reaches the photoelectric conversion module via an optical rotary joint and an optical cable. The transmitted optical signal is converted into a wireless signal 116 by the photoelectric conversion module and transferred to a signal analysis system such as a spectrum analyzer. According to the present invention it is possible to ensure the normal operation of the system even in the frequency band of GHz, to prevent secondary radiation phenomenon, to reduce the weight of the system and to simplify the configuration more.

FIG. 2 is a configuration diagram illustrating the signal measuring system shown in FIG. 1 in more detail.

The receiving antenna 202 for receiving a radio signal from a signal source is disposed at one end of the mast 204 which is height-adjustable and made of a non-metallic material. The mast 204 has a node 206, through which the mast 204 is capable of height adjustment in the same principle as adjusting the length of the fishing rod. Height adjustment of the mast is possible via the motor 212 located below. Meanwhile, the wireless signal input through the receiving antenna 202 is transmitted to the signal analysis module by the optical cable 208 composed of optical fibers. The receiving antenna 202, the mast 204, the optical cable 208, the motor 212, etc. are mounted in a mobile vehicle to measure the signal where desired, and a support for fixing the mast 204 when measuring the signal ( 210 may be used.

3 is a block diagram showing the configuration of a signal processing system according to an embodiment of the present invention.

As shown in FIG. 3, a signal processing system according to an exemplary embodiment of the present invention includes a reception antenna 304, a first all-optical converter 306, an isolator 308, a first optical rotary joint 310, and a first optical joint. Photoelectric conversion unit 312, mast 314, optical fiber 316, second photoelectric conversion unit 318, second rotating unit 320, second optical rotary joint 322, third photoelectric conversion unit 324 ), An electrical signal output porter 326, a signal analyzer 328, a second all-optical converter 330, and a controller 332.

The radio signal 302 copied from the signal source is input to the receive antenna 304. In the frequency band below 1 GHz, a half-wavelength standard dipole antenna may be used as the receiving antenna 304, and in the frequency band of 1 GHz to 4 GHz, the horn antenna may be used as the receiving antenna 304. The radio signal received by the reception antenna 304 is converted into an optical signal by the first all-optical converter 306. The first all-optical converter 306 stabilizes the power of the input wireless signal 302 and matches a low noise amplifier (LNA) to match the impedance between the receiving antenna 304 and the first all-optical converter 306. It may include. In addition, a distributed feedback laser diode (DFB LD) is used as the first all-optical converter 306 and the second all-optical converter 330. In addition, the reception antenna 304 may be connected to the first all-optical converter 306 through a subminiature coaxial connector.

Although not shown in FIG. 1, a first rotating part may be included where the first optical rotary joint 310 is disposed to change the polarization mode of the receiving antenna 304 to adjust the polarization of the optical signal. The first rotating unit adjusts the polarization mode of the receiving antenna 304 while rotating by 90 degrees. An optical fiber 316 is connected to the first rotating part for transmitting an optical signal, and the signal processing system includes a first optical rotary joint 310 to prevent the optical fiber 316 from being twisted by the rotation of the first rotating part. do. When the first optical rotary joint 310 is included, the optical signal may be returned to the first all-optical converter 306 due to a reflection phenomenon such as Fresnel reflection. Since this acts as a deadly noise in a signal processing system, an isolator 308 may be included to prevent this.

The optical signal converted by the first all-optical converter 306 moves through the optical fiber 316. On the other hand, when the signal is measured by rotating the receiving antenna 304 by 360 degrees to obtain the characteristics of the signal source according to the radiation pattern of the antenna, it is possible to obtain the maximum power and radiation pattern, such as 360 degrees of the receiving antenna 304 The second rotating part 320 is included for rotation. When the second rotating part 320 is rotated, the upper end of the second rotating part 320, that is, the receiving antenna 304, the first all-optical converting part 306, the optical fiber 316, and the like rotate together. The second optical rotary joint 322 is included to prevent the twisting of the optical fiber 316 due to the rotation of the second rotating part 320.

The optical signal moving through the optical fiber 316 is transmitted to the third photoelectric converter 324. For reference, a photo detector may be used for the first photoelectric converter 312, the second photoelectric converter 318, and the third photoelectric converter 324. The optical signal transmitted to the third photoelectric conversion unit 324 is converted into a wireless signal, where the converted wireless signal has the same frequency as that of the wireless signal 302 input through the receiving antenna 304, that is, the same It is a radio signal with characteristics. The radio signal converted by the third photoelectric conversion unit 324 is modulated into the same radio signal as the radio signal 302 through a simple amplifier, etc., and the radio signal is converted into a signal analyzer through an electrical signal output porter 326. 328).

As such, by transmitting the wireless signal 302 received through the reception antenna 304 to the signal analyzer 328 through the optical fiber 316, signal interference generated by a conductor such as a conventional RF cable may be prevented. In addition, the mast 314 consisting of a non-metallic material also helps to prevent signal interference. In addition, in order to reduce signal interference, the all-optical converters 306 and 330 and the photoelectric converters 312, 318 and 324 may be configured to have their own power sources, for example, batteries.

As described above, the signal processing system according to an embodiment of the present invention may include a first rotating part for changing the polarization mode of the receiving antenna and a second rotating part 320 capable of rotating the receiving antenna 360 degrees. The controller 332 may be configured to control the polarization mode change of the first rotating part or the rotation of the second rotating part 320. Conventionally, the control signal transmission between the control unit 332 and the rotating unit is also made through the metallic conductor, and thus interference of the signal occurs. Therefore, in one embodiment of the present invention, a control signal made of light is transmitted to each rotating unit through the optical fiber. In this case, the control signal of the controller 332 may be transmitted using the same path as that of the optical fiber 316 used to transmit the wireless signal 302, or may be transmitted through an optical fiber separate from the optical fiber 316. May be In the embodiment of the present invention illustrated in FIG. 3, it is assumed that the control signal is transmitted through the same optical fiber 316 as the transmission path of the wireless signal 302. In FIG. 3, the control signal is indicated by a thick arrow to distinguish it from the wireless signal 302.

The controller 332 outputs a control signal for controlling the rotation of the first rotating part (not shown) or the second rotating part 320. At this time, the signal output from the control unit 332 is an electrical signal. The output control signal is input to the second all-optical converter 330 and converted into an optical signal. The converted optical signal moves through the optical fiber 316 and is input to the second photoelectric converter 318. The second photoelectric converter 318 converts the input optical signal into an electrical signal identical to the control signal output from the controller 332 and outputs the same. The output control signal is input to the second rotating unit to control the rotation of the receiving antenna 304.

Meanwhile, the optical signal output from the second all-optical converter 330 moves along the optical fiber 316 and is input to the first photoelectric converter 312. The first photoelectric converter 312 converts the input optical signal into an electrical signal identical to the control signal output from the controller 332 and outputs the same. The output control signal is input to the first rotating unit (not shown) to control the polarization mode of the receiving antenna 304.

As mentioned above, in one embodiment of the present invention, a single optical fiber 316 may be used to transmit a control signal from the wireless signal 302 and the controller 332 to simplify the overall system and reduce the weight. At this time, it is possible to transfer the two signals to one optical fiber 316 by using a method of different wavelengths of the control signal of the wireless signal 302 and the control unit 332. For example, the wavelength of the wireless signal 302 converted into the optical signal by the first all-optical converter 306 is 1550 nm, and the wavelength of the control signal converted into the optical signal by the second all-optical converter 330 is 1310nm can be set differently. By varying the wavelength of the optical signal as described above, the transmission of the wireless signal 302 and the control signal can be simultaneously performed.

4 is a structural diagram illustrating the structure of a receiving antenna unit, an all-optical converting unit, an optical fiber, and a mast of the signal processing system according to an exemplary embodiment of the present invention.

As shown in Figure 4, the receiving antenna 402 is connected to one end of the mast 406 is adjustable height. The mast 406 is adjustable in height by a motor that can be installed at the bottom, and having one or more nodes 410 can be height-adjusted like an antenna of a fishing rod or a home radio.

On the other hand, the all-optical converter 404 is connected to the receiving antenna 402. The optical fiber 408 is connected to the all-optical converter 404 to transfer the optical signal converted and output by the all-optical converter 404. Although not shown in FIG. 4, between the receiving antenna 402 and the optical fiber 408, in addition to the all-optical conversion unit 404, an isolator for preventing light reflection, a polarization mode adjustment of the receiving antenna 402, or a 360 degree rotation is performed. An optical rotary joint may be further included to prevent twisting of the optical fiber 408.

5 is a configuration diagram illustrating a connection between a receiving antenna and a mast of a signal processing system according to another exemplary embodiment of the present invention.

In an embodiment of the present invention described with reference to FIG. 4, the receiving antenna 402 may be rotated 360 degrees by a rotating unit (not shown). However, when the reception antenna 402 is rotated in the structure as shown in FIG. 4, a problem arises in that the reception distance of the wireless signal is changed by the rotation. Therefore, there is a need for a structure capable of maintaining the same reception distance of a wireless signal regardless of the 360 degree rotation of the reception antenna 402.

This problem can be solved by connecting the receiving antenna 502 and the mast 512 such that the plane formed by the inlet end surface of the receiving antenna 502 and the center axis of the mast 512 are coplanar with each other. have. In another embodiment of the present invention, the receiving antenna 502 and the mast 512 to the jig 508 of the non-metallic material for this structure. When the receiving antenna 502 and the mast 512 are connected using the jig 508, the center of gravity of the receiving antenna 502 does not coincide with the center of the mast 512.

In FIG. 5, the wireless signal received through the receive antenna 502 is transmitted to the all-optical converter 506 via a short RF cable 504. The all-optical converter 506 converts the input wireless signal into an optical signal and outputs the optical signal to another module through the optical fiber 510. As mentioned above, the all-optical conversion unit 506 has its own power supply such as a battery, so it is not necessary to receive power from an external cable.

According to the present invention described so far, it is possible to always exhibit the same characteristics regardless of the frequency of the signal in the processing of the radio signal, in particular, the advantage of preventing secondary radiation caused by the use of conventional RF cable There is this.

In addition, according to the present invention it is possible to reduce the volume or weight compared to the prior art, it is possible to simplify the system configuration, there is an advantage in terms of cost.

The present invention described above is capable of various substitutions, modifications, and changes without departing from the spirit of the present invention for those skilled in the art to which the present invention pertains. It is not limited by.

1 is a diagram illustrating a wireless signal measuring system and a signal measuring environment to which a signal processing system according to the present invention is applied.

FIG. 2 is a configuration diagram illustrating the signal measuring system shown in FIG. 1 in more detail. FIG.

3 is a block diagram showing a configuration of a signal processing system according to an embodiment of the present invention.

4 is a structural diagram illustrating the structure of a receiving antenna unit, an all-optical converting unit, an optical fiber, and a mast of a signal processing system according to an embodiment of the present invention;

5 is a configuration diagram illustrating a connection between a receiving antenna and a mast of a signal processing system according to another embodiment of the present invention.

Claims (10)

A receiving antenna for receiving a wireless signal; An all-optical converting unit converting the wireless signal into an optical signal; An optical fiber for transmitting the optical signal; A photoelectric conversion unit converting the optical signal transmitted through the optical fiber into the wireless signal; And A first rotating part for changing the polarization mode of the receiving antenna Signal processing system comprising. delete The method according to claim 1, And a second rotating part capable of rotating the receiving antenna 360 degrees. The method of claim 3, A control unit for changing a polarization mode of the first rotating unit or controlling the rotation of the second rotating unit; And And a optical rotary joint disposed between the receiving antenna and the controller. 5. The method of claim 4, And an isolator disposed between the receive antenna and the optical rotary joint. The method according to claim 1, The mast further includes a mast disposed at one end, And an entrance end face of the receiving antenna and a center axis of the mast are coplanar with each other. The method according to claim 6, The mast is Signal processing system with adjustable height and composed of non-metallic material. Receiving a wireless signal; Converting the wireless signal into an optical signal; Transmitting the optical signal through an optical fiber; Converting the optical signal transmitted through the optical fiber into the wireless signal; And Controlling a polarization mode change of the receiving antenna; The wireless signal is received by the receive antenna Signal processing method. delete The method of claim 8, The receiving antenna is rotatable 360 degrees, And controlling the rotation of the receiving antenna.

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