JP4369902B2 - Electric field strength calculation apparatus, electric field strength calculation method, and electric field strength calculation program - Google Patents

Description

  The present invention relates to radio wave measurement technology and signal processing technology in an area where a single frequency network (SFN) is incorporated, and in particular, an electric field for calculating the electric field strength of radio waves transmitted from each relay station. The present invention relates to an intensity calculation device, an electric field intensity calculation method, and an electric field intensity calculation program.

  Conventionally, in broadcasting based on Orthogonal Frequency Division Multiplexing (OFDM), a broadcast wave (OFDM wave) transmitted in an SFN environment is demodulated by an OFDM demodulator, and a constellation (signal arrangement diagram) is obtained. Observe and measure a modulation error ratio (MER), and extract a scattered pilot signal (SP signal) inserted in the OFDM wave and having a known amplitude and phase, Using this extracted SP signal, the DU ratio (D / D) indicating the ratio of the intensity of the direct wave of the OFDM wave and the delayed wave (reflected wave, scattered wave, sneak wave) delayed by the multipath. U; Desired to Undesired ratio ) And a delay profile including the delay time of the delayed wave (hereinafter referred to as SP method) has been proposed.

  Further, a method is disclosed in which an OFDM wave transmitted in an SFN environment is observed with a spectrum analyzer, and an amplitude frequency characteristic of the OFDM wave is analyzed by FFT (Fast Fourier Transform) (Patent Document 1). reference).

Conventionally, when calculating the electric field strength of a radio wave transmitted from each relay station in an SFN environment, first, the antenna is directed to each relay station, and the electric field strength and delay profile of the received radio wave are calculated. It was measured with a measuring instrument, and then the measured data was analyzed and calculated.
Japanese Unexamined Patent Publication No. 2001-223666 (paragraph numbers 0021 to 0024, FIGS. 1 and 2)

  However, in the SFN environment, the radio waves transmitted from each transmission station are on the same channel, and therefore, the radio waves obtained by combining the radio waves from a plurality of transmission stations are observed by the measuring instrument. Since there was no method for analyzing the electric field strength of each transmitting station from the synthesized radio wave, the electric field strength of the radio wave from each transmitting station could not be measured accurately.

  The present invention has been made to solve the above-described problems of the prior art, and is an electric field strength calculation device capable of instantaneously and accurately measuring the electric field strength of radio waves from each transmitting station in an SFN environment. An object of the present invention is to provide an electric field intensity calculation method and an electric field intensity calculation program.

  In order to solve the above-described problem, the electric field intensity calculation device according to claim 1 is transmitted from a measurement target transmission station that is a measurement target transmission station and other transmission stations received by an antenna in a single frequency network. A field strength calculation device for calculating a field strength of a transmission station, which is a field strength of a signal transmitted from the measurement target transmission station, on the basis of an OFDM signal composed of a plurality of received signals. And a DU ratio measuring means and a transmitting station electric field strength calculating means.

  According to this configuration, the field strength calculation device measures the field strength of the OFDM signal received in the direction corresponding to the measurement target transmission station with the antenna by the reception field strength measurement unit, and measures the measurement target by the DU ratio measurement unit. Based on the position information of the transmitting station and other transmitting stations, the DU ratio, which is the ratio of the strength of the signal transmitted from the measuring target transmitting station and the signal transmitted from the other transmitting station in the OFDM signal, is measured. In addition, the field strength calculating device uses the field strength Em measured by the reception field strength measurement means and the DU ratio (D / U) measured by the DU ratio measurement means by the transmission station field strength calculation means. The electric field strength E is calculated by the following equation (1).

  Thereby, the electric field strength calculating apparatus measures the electric field strength and the DU ratio from the radio wave received by the antenna directed to the transmission station to be measured, and from the transmitting station based on the electric field strength and the DU ratio. It is possible to calculate the field strength of the transmitting station of the radio wave.

  According to a second aspect of the present invention, there is provided an electric field strength calculation method comprising: a plurality of signals transmitted from a measurement target transmission station that is a measurement target transmission station and other transmission stations, received by an antenna in a single frequency network; An electric field strength calculation method for calculating a transmission station electric field strength, which is an electric field strength of a signal transmitted from the measurement target transmission station, on the basis of an OFDM signal composed of: an electric field strength / DU ratio measuring step; A local electric field intensity calculating step.

  According to this method, in the electric field intensity / DU ratio measurement step, the electric field intensity of the OFDM signal received by the antenna in the direction corresponding to the measurement target transmission station is measured, and the positions of the measurement target transmission station and other transmission stations are measured. DU ratio, which is the ratio of the intensity of the signal transmitted from the measurement target transmission station to the signal transmitted from another transmission station in the OFDM signal, is measured in the transmission station electric field strength calculation step. From the electric field intensity Em and the DU ratio (D / U) measured in the intensity / DU ratio measurement step, the transmission station electric field intensity E is calculated by the following equation (1).

  Thereby, the electric field strength and the DU ratio are measured from the radio wave received by the antenna directed to the transmission station to be measured, and the transmission station electric field of the radio wave from the transmission station is measured based on the electric field strength and the DU ratio. The intensity can be calculated.

  According to a third aspect of the present invention, there is provided a program for calculating an electric field strength, wherein a plurality of signals transmitted from a measurement target transmission station that is a measurement target transmission station and other transmission stations are received by an antenna in a single frequency network. Based on an OFDM signal comprising: a computer for calculating a transmission station field strength which is a field strength of a signal transmitted from the measurement target transmission station; a reception field strength measurement means; a DU ratio measurement means; a transmission station It was made to function as electric field strength calculation means.

  According to such a configuration, the field strength calculation program measures the field strength of the OFDM signal received in the direction corresponding to the measurement target transmission station by the antenna by the reception field strength measurement unit, and measures the measurement target by the DU ratio measurement unit. Based on the position information of the transmitting station and other transmitting stations, the DU ratio, which is the ratio of the strength of the signal transmitted from the measuring target transmitting station and the signal transmitted from the other transmitting station in the OFDM signal, is measured. In addition, the field strength calculating device uses the field strength Em measured by the reception field strength measurement means and the DU ratio (D / U) measured by the DU ratio measurement means by the transmission station field strength calculation means. The electric field strength E is calculated by the following equation (1).

  Thereby, the electric field strength calculation program measures the electric field strength and the DU ratio from the radio wave received by the antenna directed to the transmission station to be measured, and from the transmitting station based on the electric field strength and the DU ratio. It is possible to calculate the field strength of the transmitting station of the radio wave.

  The electric field intensity calculation device, electric field intensity calculation method, and electric field intensity calculation program according to the present invention have the following excellent effects. According to the first, second, or third aspect of the invention, it is possible to instantaneously calculate the transmission station electric field intensity of the radio wave from each transmission station and not to analyze the antenna directivity. Therefore, it is possible to calculate the transmission station electric field intensity of the radio wave from each transmission station with high accuracy, with little influence of the antenna setting error.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(Configuration of electric field strength calculation device)
First, the configuration of the electric field intensity calculation device 1 will be described with reference to FIG. FIG. 1 is a block diagram showing a configuration of an electric field strength calculating apparatus according to the present invention.

  The electric field strength calculating apparatus 1 receives broadcast waves (OFDM signals) received by an antenna (not shown) and uses the electric field strengths of the signals transmitted from a plurality of relay stations (transmitting stations) included in the OFDM signals. A certain relay station electric field strength (transmitting station electric field strength) is calculated. The electric field strength calculating device 1 includes a band pass filter 10, a high frequency amplification means 11, a channel selection means 12, an intermediate frequency conversion means 13, an intermediate frequency amplification means 14, a band pass filter 15, a detection means 16, Reception field strength measurement means 17, A / D conversion means 18, delay profile measurement means 19, measurement value storage means 20, relay station field strength calculation means 21, measurement channel input means 22, transmission specification storage Means 23, measurement relay station selection means 24, measurement point information input means 25, and video display means 26 are provided.

  Here, the OFDM signal received here will be described with reference to FIG. FIG. 2 is an explanatory diagram for explaining an OFDM signal obtained by an antenna that receives radio waves transmitted from two relay stations in an SFN environment and input to an electric field strength calculation apparatus according to the present invention. (A) is explanatory drawing for demonstrating the electromagnetic wave from two relay stations received by an antenna in SFN environment, (b) is the spectrum of the OFDM signal received by the antenna, and the said OFDM signal It is a schematic diagram which shows typically the spectrum of the electromagnetic wave transmitted from each included relay station.

As shown in FIG. 2A, the radio waves transmitted from the relay station I _A and the relay station I _B are received by the antenna A in the SFN environment. Therefore, as shown in FIG. 2 (b), the OFDM signal W _O that is received here, the radio wave W _B transmitted from the radio wave W _A and the relay station I _B transmitted from the relay station I _A are combined OFDM signal.

  Returning to FIG. 1, the description will be continued. The band-pass filter 10 is a filter that passes only the frequency component of an OFDM signal [RF (Radio Frequency) signal] of the input signal. The OFDM signal that has passed through the bandpass filter 10 is output to the high frequency amplification means 11.

  The high frequency amplification means 11 amplifies the voltage of the OFDM signal input from the band pass filter 10. The OFDM signal amplified here is output to the channel selection means 12. Further, the gain value of the high frequency amplification means 11 is output to the reception electric field strength measurement means 17.

  The channel selection unit 12 extracts a signal of the physical channel based on the information of the physical channel input from the measurement channel input unit 22. The signal extracted here is output to the intermediate frequency conversion means 13. Note that the channel selection unit 12 includes, for example, an amplifier that amplifies the signal of the physical channel based on the information of the physical channel input from the measurement channel input unit 22, and a filter that removes signals of other physical channels. can do.

  The intermediate frequency conversion means 13 converts the frequency of the signal (RF signal) input from the channel selection means 12 to an intermediate frequency signal [IF (Intermediate Frequency) signal]. The converted intermediate frequency signal is output to the intermediate frequency amplification means 14.

  The intermediate frequency amplification means 14 amplifies the signal input from the intermediate frequency conversion means 13. The amplified signal is output to the band pass filter 15. The gain value of the intermediate frequency amplifying unit 14 is output to the received electric field strength measuring unit 17.

  The band pass filter 15 is a filter that allows only the intermediate frequency component of the signal input from the intermediate frequency amplifying means 14 to pass therethrough. The signal that has passed through the bandpass filter 15 is output to the detection means 16 and the A / D conversion means 18.

  The detection means 16 detects the power value of the signal input from the bandpass filter 15. The signal indicating the power value generated here is output to the received electric field strength measuring means 17.

The received electric field strength measuring unit 17 calculates the electric field strength of the input OFDM signal based on the gain value of the high frequency amplifying unit 11, the gain value of the intermediate frequency amplifying unit 14, and the power value detected by the detecting unit 16. Measure. Here, when the gain value of the high frequency amplification means 11 is G _h [dB], the gain value of the intermediate frequency amplification means 14 is G _m [dB], and the power value detected by the detection means 16 is P [dB], the electric field The intensity is P · G _m · G _h . The electric field strength measured here is stored in the measured value storage means 20 and output to the video display means 26.

  The A / D conversion means 18 converts the signal input from the band pass filter 15 into a digitized signal. The signal digitized here is input to the delay profile measuring means 19.

  The delay profile measurement means (DU ratio measurement means) 19 includes a signal input from the A / D conversion means 18, information on latitude and longitude of a plurality of relay stations input from the measurement relay station selection means 24, and a delay adjustment amount. And the ratio of the intensity of the signal transmitted from each of the plurality of relay stations by measuring the delay profile based on the latitude and longitude (antenna position) information of the measurement point input from the measurement point information input means 25 DU ratio is measured. Here, the measured DU ratio is stored in the measured value storage means 20 and output to the video display means 26. The delay adjustment amount indicates a time for adjusting the timing of transmitting a radio wave set in each relay station so that the delay time of the delayed wave is within the guard interval.

  Here, referring to FIG. 3 (refer to FIG. 1 as appropriate), a method in which the delay profile measuring means 19 measures the DU ratio of signals from two relay stations will be described using a specific example. FIG. 3 is an explanatory diagram for explaining how the delay profile measuring means measures the DU ratio of signals from two relay stations. FIG. 3A schematically shows the arrangement of two relay stations and antennas. (B) is a graph showing an example of a delay profile of a signal received by an antenna.

First, the delay profile measuring means 19 includes the latitude and longitude information and delay adjustment amount of the two relay stations, the latitude and longitude information of the measurement point (position of the antenna A) input from the measurement point information input means 25, Based on the above, the delay time of the signal from each relay station is calculated. For example, as shown in FIG. 3 (a), the distance from the relay station I _A to the antenna A installed toward the relay station I _A is 11.7km, distance from the relay station I _B to the antenna A is 13 When the delay is not adjusted on the transmission side at .2 km, the difference between the distances of the two relay stations I _A and I _{B to} the antenna A is 1.5 km, and the delay profile measuring means 19 determines the difference between the distances. the radio wave propagation speed (0.3km / μsec) divided by the value (5 .mu.sec), calculated as the delay time for the signal from the relay station I _a signal from the relay station I _B.

  Further, for example, the distance from one relay station (not shown) to the measurement point is 10 km, and the distance from the other relay station (not shown) to the measurement point is 13 km. In this relay station, the delay is +30 μsec. When the adjustment amount is set, the delay time of the radio wave transmitted from this relay station is 40 μsec {(13 [km] −10 [km]) / 0.3 [km / μsec] +30 [μsec] }.

Subsequently, the delay profile measuring means 19 measures the delay profile based on the signal input from the A / D conversion means 18 and measures the DU ratio. Here, the delay profile measurement means 19 can measure the delay profile using the SP signal included in the signal input from the A / D conversion means 18 and measure the DU ratio. For example, as shown in FIG. 3 (b), the delay profile measuring unit 19 detects the peak P _A of the SP signals included in the signal from the relay station I _A, to the intensity of the peak P _A, A / The intensity ratio of the signal input from the D conversion means 18 is measured, and a delay profile indicating the relationship between the intensity ratio and the delay time from the time when the SP signal is input is generated. Then, the delay profile measuring means 19 sets the peak P _B at the time delayed from the time when the peak P _A was received by the calculated delay time as the peak of the SP signal from the relay station I _B , and the intensity of this SP signal. Is measured as the DU ratio. In FIG. 3 (b), the delay time is the SP signals from the relay station I _B peaks at 5 .mu.sec, the ratio of the intensity of the time (11 [dB]) is measured as a DU ratio.

  Returning to FIG. 1, the description will be continued. The measurement value storage means 20 stores the electric field strength and DU ratio of the signal of the physical channel input from the measurement channel input means 22, and is a general storage means such as a semiconductor memory or a hard disk. The stored field strength and DU ratio are read out when the relay station field strength calculation means 21 described later calculates the relay station field strength of the relay station to be measured.

  The relay station electric field strength calculating means (transmitting station electric field strength calculating means) 21 reads the electric field strength and the DU ratio stored in the measured value storage means 20, and calculates the relay station electric field strength of the relay station to be measured. Is. The relay station electric field strength calculated here is output to the video display means 26.

Here, with reference to FIG. 4 (refer to FIG. 1 as appropriate), a method of calculating the relay station electric field strength by the relay station electric field strength calculation means 21 will be described. FIG. 4 schematically shows the electric field strength of the signals from the two relay stations, the electric field strength and DU ratio of the signal received by the antenna, and the direction of the antenna measured by the electric field strength calculation apparatus according to the present invention. FIG. 4A is a schematic diagram illustrating a state in which an antenna is directed to the relay station I _A, and FIG. 4B is a schematic diagram illustrating a state in which the antenna is directed to the relay station I _B.

As shown in FIG. 4 (a), the antenna A, and the signal of the electric field strength (RS field strength) Ea from the relay station I _A, and the signal of relay station I field strength (RS field strength) from _B Eb is when received, the antenna a is directed towards the relay station I _a, and the direction of an angle θ with respect to the orientation of the antenna a has a relay station I _B. Then, it is assumed that the field intensity of the OFDM signal received by the antenna A is Ema and the DU ratio is (D / U _a ). Further, as shown in FIG. 4 (b), the electric field intensity of the OFDM signal received by the antenna A in a state with its antenna A to the relay station I _B is Emb, DU ratio met (D / U _b) Suppose.

Here, in the case with its antenna A in the direction of the relay stations I _A, the directional function of an antenna A and D (θ) _ant1 respect to the direction of the relay stations I _B, towards the antenna A in the direction of the relay stations I _B When the directivity function of the antenna _A with respect to the direction of the relay station I _A is D (θ) _ant2 , the following relationships (2) to (5) are established.
Ema ² = Ea ² + {Eb · D (θ) _ant1 } ² (2)
D / U _a = Ea / (Eb · D (θ) _ant1 ) (3)
Emb ² = {Ea · D (θ) _ant2 } ² + Eb ² (4)
D / U _b = Eb / (Ea · D (θ) _ant2 ) (5)

  Then, when formulas (2) to (5) are summarized for relay station electric field strength Ea and relay station electric field strength Eb, the following formulas (6) and (7) are derived.

Therefore, relay station field strength calculation unit 21, when calculating the relay station field intensity Ea of the relay station I _A, the field strength Ema and DU ratio stored in the measured value storing means 20 and (D / U _a) Is read. Then, the relay station electric field strength calculation means 21 can calculate the relay station electric field strength Ea based on the equation (6). Similarly, relay station field strength calculation unit 21, the relay station when calculating the relay station field intensity Eb of the I _B, the electric field strength Emb stored in the measurement value storage unit 20 and the DU ratio (D / U _b) And read. Then, the relay station electric field strength calculating means 21 can calculate the relay station electric field strength Eb based on the equation (7).

The field strength Ema and the field strength Emb can be measured, and the relay station field strength can be calculated from the above formulas (2) and (4) based on the directivity of the antenna A. In the region where the directivity changes greatly due to the change in the angle θ (in the vicinity of θ = 90 ° in FIG. 4), the adjustment deviation in the direction of the antenna A greatly affects the calculation result. To do. Furthermore, according to the directivity of the antenna A, when the two relay stations I _A and I _B are in the same direction, the relay station electric field strength cannot be calculated.

  On the other hand, the relay station electric field strength calculation means 21 calculates the relay station electric field strength based on the measured electric field strength and the DU ratio, so that the influence of the setting error of the antenna A is small and the relay station electric field strength is highly accurate. Since the delay profile can be measured even when the relay station is in the same direction, the relay station electric field strength can be calculated.

  Returning to FIG. 1, the description will be continued. The measurement channel input means 22 inputs information on the physical channel to be measured from the outside. The information on the physical channel input here is output to the channel selection means 12.

  The transmission specification storage means 23 stores latitude and longitude information and delay adjustment amounts of various relay stations, and is a general storage means such as a semiconductor memory or a hard disk. The latitude and longitude information and the delay adjustment amount stored here are read out by the measurement relay station selection means 24 described later.

  Based on a command from the outside, the measurement relay station selection unit 24 reads out the latitude and longitude information and delay adjustment amount of the relay station to be measured, which are indicated by the command, from the transmission specification storage unit 23. . The read latitude and longitude information and delay adjustment amount of the relay station read out here are output to the delay profile measuring means 19.

  The measurement point information input means 25 inputs the latitude and longitude information of the measurement point (antenna position) from the outside. The information on the latitude and longitude of the measurement point input here is output to the delay profile measuring means 19.

  The video display unit 26 generates a screen image for receiving an instruction from the user, and also measures the measurement result of the electric field strength input from the received electric field strength measurement unit 17 and the DU ratio input from the delay profile measurement unit 19. A screen image for displaying the result and the calculation result of the relay station electric field strength input from the relay station electric field strength calculating means 21 is generated and output to a display device (not shown).

  As described above, the electric field strength calculating apparatus 1 uses the relay station electric field that is the electric field strength of the signal from the relay station based on the signal received by the antenna directed toward the relay station to be measured for the electric field strength. The intensity can be calculated. The electric field strength calculating apparatus 1 can calculate the relay station electric field strength with high accuracy with little influence of an antenna setting error.

  The electric field strength calculation apparatus 1 can also realize each means as a function program in a computer, and can also be operated as a field strength calculation program by combining the function programs.

[Screen example of field strength calculation device]
Here, referring to FIG. 5 (refer to FIG. 1 as appropriate), an example of a screen for registering information necessary for calculating the relay station electric field strength and displaying the calculation result will be described. FIG. 5 is a schematic diagram illustrating an example of a screen for registering information necessary for calculating the relay station electric field strength, which is presented to the user by the electric field strength calculating device, and displaying the calculation result.

  As shown in FIG. 5, the screen W mainly includes operation buttons (b1 to b8), a map display area R1, a relay station information display area R2, and a measurement result display area R3. The operation buttons (b1 to b8), the map display area R1, the relay station information display area R2, and the measurement result display area R3 are displayed by the video display means 26.

  The electric field strength calculating device 1 uses the video display means 26 to measure the latitude / longitude registration button b1, the relay station latitude / longitude registration button b2, the measurement channel relay station direction selection button b3, the measurement button b4, and the measurement stop button b5. Then, a measurement result display button b6, a relay station electric field strength calculation button b7, and a power button b8 are displayed. Here, the measurement point latitude / longitude registration button b1 is an operation button for inputting a command for causing the measurement point information input means 25 to display a screen for inputting latitude and longitude information of the measurement point, and relay station latitude / longitude registration. The button b2 is an operation button for inputting a command for displaying a screen for inputting the latitude and longitude information of the relay station to be stored in the transmission specification storage means 23, and the measurement channel relay station direction selection button b3 is a measurement button. This is an operation button for inputting a command for selecting a target relay station and displaying a screen for inputting information of a physical channel to be measured.

  The measurement button b4 is an operation button for inputting a measurement start command, the measurement stop button b5 is an operation button for inputting a measurement stop command, and the measurement result display button b6 is a field strength and DU ratio. An operation button for inputting a command for displaying a measurement result, the relay station field strength calculation button b7 is an operation button for inputting a command to start calculation of the relay station field strength, and a power button b8 is used to end the display screen. This is an operation button for inputting a command.

  The map display area R1 is an area for displaying a map near the relay station to be measured. The relay station information display area R2 is an area for displaying information on the relay station to be measured. Further, the measurement result display region R3 is displayed by the measurement result of the electric field intensity measured by the reception electric field intensity measurement unit 17, the measurement result of the DU ratio measured by the delay profile measurement unit 19, and the relay station electric field intensity calculation unit 21. This is an area for displaying the calculated result of the calculated relay station electric field strength. Thereby, the user can confirm the measurement result of the electric field strength, the measurement result of the DU ratio, and the calculation result of the relay station electric field strength, and use the operation buttons (b1 to b8) with a mouse (not shown) or the like. By clicking, a command corresponding to the operation buttons (b1 to b8) can be input and executed.

[Operation of electric field strength calculation device]
Next, with reference to FIG. 6 (refer to FIG. 1 as appropriate), an operation in which the electric field strength calculation apparatus 1 according to the present invention calculates the relay station electric field strength of the signal from each relay station will be described. FIG. 6 is a flowchart showing the operation of the field strength calculation apparatus according to the present invention for calculating the relay station field strength of the signal from each relay station.

  First, the electric field strength calculating device 1 inputs the latitude and longitude information of the measurement point from the outside by the measurement point information input means 25 (step S11). Subsequently, the electric field strength calculating apparatus 1 inputs information indicating the relay station to be measured from the outside by the measurement relay station selecting unit 24 (step S12).

  Next, the electric field strength calculating apparatus 1 inputs information of the physical channel to be measured from the outside by the measurement channel input means 22 (step S13). Then, the electric field intensity calculation device 1 receives the OFDM signal from the band pass filter 10 (step S14). The OFDM signal input here is a signal received in step S12 and received by an antenna installed in the direction of the relay station to be measured.

  Subsequently, the electric field strength calculating apparatus 1 measures the electric field strength of the OFDM signal input in step S14 and measures the delay profile to obtain the DU ratio (step S15; electric field strength / DU ratio measuring step).

  Here, the electric field strength calculating apparatus 1 first removes signals other than the frequency components of the OFDM signal from the OFDM signal (RF signal) input in step S14 by the bandpass filter 10, and then the high frequency amplification means. 11 amplifies the voltage of this OFDM signal. Then, the electric field strength calculating device 1 extracts the signal of the physical channel from this signal based on the information of the physical channel to be measured input in step S13 by the channel selection unit 12, and the intermediate frequency conversion unit 13 Then, frequency conversion is performed to generate an intermediate frequency signal (IF signal).

  Subsequently, the electric field intensity calculation device 1 amplifies the IF signal by the intermediate frequency amplification unit 14 and removes signals other than the intermediate frequency component by the band pass filter 15. Then, the electric field strength calculating device 1 detects the power value of the signal input from the bandpass filter 15 by the detection unit 16, and converts the power value of the signal detected by the detection unit 16 by the reception field strength measurement unit 17. The electric field strength of the OFDM signal is measured by multiplying the gain value of the high frequency amplification means 11 and the gain value of the intermediate frequency amplification means 14.

  Furthermore, the electric field strength calculating device 1 converts the signal input from the bandpass filter 15 into a digitized signal by the A / D conversion means 18 and the information input in step S12 by the measurement relay station selection means 24. The information on the latitude and longitude of the relay station to be measured and the delay adjustment amount are read from the transmission specification storage means 23. Then, the delay profile measuring means 19 measures the delay profile from the signal digitized by the A / D converting means 18, and further, the latitude and longitude information of the relay station to be measured, the delay adjustment amount, and step S11. Based on the latitude and longitude information of the measurement point input at, the delay time of the signal of the other relay station relative to the signal of the relay station to be measured is calculated, from the delay profile, from each of the plurality of relay stations Measure the DU ratio, which is the ratio of the intensity of the transmitted signals. As described above, the electric field strength calculating apparatus 1 can measure the electric field strength and the DU ratio. At this time, the electric field intensity calculation device 1 outputs the measurement result to a display device (not shown) connected to the outside via the video display means 26.

  And the electric field strength calculation apparatus 1 memorize | stores the delay profile and DU ratio measured in step S15 in the measured value memory | storage means 20 (step S16).

  Subsequently, the electric field strength calculating apparatus 1 determines whether the measurement relay station selecting unit 24 has measured the electric field strength and the DU ratio for all the transmission stations to be measured (step S17). If measurement has not been completed for all transmitting stations (No in step S17), the process returns to step S13, and the electric field intensity calculation device 1 uses the measurement channel input means 22 to externally measure the physical channel to be measured. The operation after the operation to input the information is performed.

  On the other hand, when the measurement is performed for all the transmitting stations (Yes in step S17), the electric field strength calculating apparatus 1 uses the relay station electric field strength calculating unit 21 to store the electric field strength stored in the measured value storage unit 20 in step S16. And the DU ratio are read, and the electric field strength (relay station electric field strength) of the signal from the relay station to be measured is calculated (step S18; transmitting station electric field strength calculation step).

  Then, the electric field strength calculating device 1 converts the calculation result calculated in step S18 into a displayable output format by the video display means 26, and outputs it to a display device (not shown) connected to the outside (step S19). ), The operation ends.

It is the block diagram which showed the structure of the electric field strength calculation apparatus in this invention. It is explanatory drawing for demonstrating the OFDM signal obtained by the antenna which received the electromagnetic wave transmitted from two relay stations in the environment of SFN, and input into the electric field strength calculation apparatus in this invention, (a) FIG. 4B is an explanatory diagram for explaining radio waves from two relay stations received by an antenna in an SFN environment, and FIG. 4B is a diagram illustrating the spectrum of an OFDM signal received by the antenna and each of the OFDM signals included in the OFDM signal. It is a schematic diagram which shows typically the spectrum of the signal of the electromagnetic wave from a relay station. It is explanatory drawing for demonstrating the method in which the delay profile measurement means of the electric field strength calculation apparatus in this invention measures the DU ratio of the signal from two relay stations, (a) is two relay stations, an antenna, (B) is a graph which shows the example of the delay profile of the signal received by an antenna. The schematic diagram which shows typically the relay station electric field strength of the signal from two relay stations measured by the electric field strength calculation apparatus in this invention, the electric field strength and DU ratio of the signal received by an antenna, and the direction of an antenna and a, (a) represents a schematic diagram showing a state with its antenna to relay station I _a, (b) is a schematic view showing a state with its antenna to relay station I _B. It is a schematic diagram which shows an example of the screen for registering the information required for calculation of the relay station electric field strength which is shown to the user by the electric field strength calculation device according to the present invention and displaying the calculation result. 5 is a flowchart showing an operation of the field strength calculation apparatus according to the present invention for calculating the relay station field strength of a signal from each relay station.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Field strength calculation apparatus 10 Band pass filter 11 High frequency amplification means 12 Channel selection means 13 Intermediate frequency conversion means 14 Intermediate frequency amplification means 15 Band pass filter 16 Detection means 17 Reception electric field strength measurement means 18 A / D conversion means 19 Delay profile measurement Means (DU ratio measuring means)
20 Measurement value storage means 21 Relay station field strength calculation means (transmission station field strength calculation means)
22 Measurement channel input means 23 Transmission specification storage means 24 Measurement relay station selection means 25 Measurement point information input means 26 Video display means

Claims (3)

In a single frequency network, based on an OFDM signal composed of a plurality of signals transmitted from a measurement target transmission station that is a transmission target to be measured and other transmission stations, received by the antenna, the measurement target transmission An electric field strength calculating device for calculating a transmitting station electric field strength which is an electric field strength of a signal transmitted from a station,
Received field strength measuring means for measuring the field strength of the OFDM signal received by the antenna in a direction corresponding to the measurement target transmitting station;
Based on the position information of the measurement target transmission station and the other transmission station, the ratio of the strength of the signal transmitted from the measurement target transmission station and the signal transmitted from the other transmission station in the OFDM signal A DU ratio measuring means for measuring a DU ratio;
From the electric field intensity Em measured by the receiving electric field intensity measuring means and the DU ratio (D / U) measured by the DU ratio measuring means, the transmitting station electric field intensity E is

Transmitting station electric field strength calculating means for calculating by the equation (1),
An electric field strength calculation device comprising: In a single frequency network, based on an OFDM signal composed of a plurality of signals transmitted from a measurement target transmission station that is a transmission target to be measured and other transmission stations, received by the antenna, the measurement target transmission A field strength calculation method for calculating a transmission station field strength that is a field strength of a signal transmitted from a station,
In the OFDM signal, the field strength of the OFDM signal received in the direction corresponding to the measurement target transmission station by the antenna is measured, and based on the position information of the measurement target transmission station and the other transmission station, An electric field strength / DU ratio measuring step for measuring a DU ratio, which is a ratio of the strength of a signal transmitted from the measurement target transmission station and a signal transmitted from the other transmission station;
From the electric field intensity Em measured in the electric field intensity / DU ratio measurement step and the DU ratio (D / U), the transmission station electric field intensity E is calculated as follows:

A transmitting station electric field intensity calculating step calculated by the equation (1);
An electric field strength calculation method comprising: In a single frequency network, based on an OFDM signal composed of a plurality of signals transmitted from a measurement target transmission station that is a transmission target to be measured and other transmission stations, received by the antenna, the measurement target transmission A computer to calculate the transmitting station field strength, which is the field strength of the signal transmitted from the station,
Received field strength measuring means for measuring the field strength of the OFDM signal received by the antenna in a direction corresponding to the measurement target transmitting station;
Based on the position information of the measurement target transmission station and the other transmission station, the ratio of the strength of the signal transmitted from the measurement target transmission station and the signal transmitted from the other transmission station in the OFDM signal A DU ratio measuring means for measuring a DU ratio;
From the electric field intensity Em measured by the receiving electric field intensity measuring means and the DU ratio (D / U) measured by the DU ratio measuring means, the transmitting station electric field intensity E is

An electric field strength calculation program that functions as a transmitting station electric field strength calculation means that is calculated by the equation (1).

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