JP3972057B2 - Measuring device, measuring method, measuring program and recording medium - Google Patents

Description

The present invention relates to a measuring apparatus, a measuring method, a measuring program, and a recording medium. In particular, the present invention relates to a measurement apparatus, a measurement method, a measurement program, and a recording medium that measure a carrier frequency phase difference and a skew between a plurality of transmitters that transmit data signals in parallel using a plurality of subcarriers. This application is related to the following Japanese application. For designated countries where incorporation by reference of documents is permitted, the contents described in the following application are incorporated into this application by reference and made a part of this application.
1. Japanese Patent Application No. 2005-367828 Filing date December 21, 2005 Japanese Patent Application No. 2006-137058 Filing Date May 16, 2006

  MIMO (Multiple Input Multiple Output) is known as a spatial multiplexing transmission technique for wireless communication. According to the communication apparatus using MIMO, a plurality of transmission signals can be transmitted simultaneously from the transmission side to the reception side using the same frequency. MIMO is planned to be adopted in, for example, IEEE 802.11n.

  A communication device using MIMO or the like includes a plurality of transmitters therein. The plurality of transmitters have a carrier signal phase error (carrier frequency phase difference). When the carrier frequency phase difference is large, the phase rotation of the frequency characteristic applied to the propagation path becomes large. Therefore, the communication device using MIMO cannot accurately reproduce the frequency characteristic of the propagation path, and as a result, good Communication is not possible. Therefore, a communication apparatus using MOMO needs to measure the carrier frequency phase difference between a plurality of transmitters in advance and perform calibration so that the influence of the carrier frequency phase difference does not affect the communication. In addition, in the plurality of transmitters, a skew is generated between the transmission signals due to the output delay of each transmitter, and a phase error depending on the frequency occurs for each subcarrier.

  In addition, since the presence of a prior art document is not recognized at this time, the description regarding a prior art document is abbreviate | omitted.

  By the way, the measuring apparatus displays a plurality of transmission signals output from a plurality of transmitters on an oscilloscope, and measures a carrier frequency phase difference and a skew. However, the measurement apparatus must have a very high-speed and wide-band oscilloscope when the carrier signal of the transmission signal is in the GHz band. In addition, the measuring device requires a channel corresponding to the number of transmitters. In addition, when measuring an OFDM signal or the like in which information is modulated on a large number of subcarriers, it is difficult for the measuring apparatus to accurately measure the carrier frequency phase difference and the skew by eliminating the frequency characteristics and the like.

  Therefore, an object of the present invention is to provide a measuring apparatus, a measuring method, a measuring program, and a recording medium that can solve the above-described problems. This object is achieved by a combination of features described in the independent claims. The dependent claims define further advantageous specific examples of the present invention.

  In order to solve the above-described problem, in the first embodiment of the present invention, there is provided a measuring apparatus that measures a carrier frequency phase difference between a plurality of transmitters that transmit a data signal in parallel using a plurality of subcarriers. Thus, at a first timing, a first transmission control is made to transmit, from the first transmitter, a first transmission signal obtained by modulating a first data signal using a subcarrier that does not overlap with a subcarrier used for transmission by a transmitter other than the first transmitter. And a second transmission signal obtained by modulating the first data signal by the subcarrier in a state where the transmitter other than the second transmitter does not transmit the subcarrier used for transmitting the first transmission signal at the second timing. And a first combined signal obtained by combining a plurality of transmission signals transmitted in parallel from a plurality of transmitters at a first timing. A combining unit that outputs a second combined signal obtained by combining a plurality of transmission signals transmitted in parallel from a plurality of transmitters at a second timing, and a sampling unit that samples the first combined signal and the second combined signal, respectively. The transmission signal for each subcarrier included in the first transmission signal is extracted from the sampled first combined signal, and the transmission signal for each subcarrier included in the second transmission signal is extracted from the sampled second combined signal. From the extraction unit, the transmission signal for each subcarrier included in the first transmission signal, and the transmission signal for each subcarrier included in the second transmission signal, the phase delay for each subcarrier of the second transmission signal with respect to the first transmission signal And a carrier between the first transmitter and the second transmitter based on the phase delay calculated by the first phase difference calculator and the first phase difference calculator Providing a measuring device and a carrier frequency phase difference calculating unit for calculating a wave number retardation.

  According to a second aspect of the present invention, there is provided a measuring apparatus for measuring a skew between a plurality of transmitters that transmit a data signal in parallel using a plurality of subcarriers, and at the first timing, the first transmitter A first transmission control unit that causes the first transmitter to transmit a first transmission signal obtained by modulating the first data signal using subcarriers that do not overlap with subcarriers used for transmission by other transmitters, and second transmission at the second timing. Second transmission in which a second transmission signal obtained by modulating the first data signal by the subcarrier is transmitted from the second transmitter in a state where transmission by the subcarrier used for transmission of the first transmission signal is not performed by a transmitter other than the transmitter. A control unit, a first combined signal obtained by combining a plurality of transmission signals transmitted in parallel from a plurality of transmitters at a first timing, and a plurality of transmitters at a second timing A synthesis unit that outputs a second synthesized signal obtained by synthesizing a plurality of transmission signals transmitted in parallel, a sampling unit that samples each of the first synthesized signal and the second synthesized signal, and a sampled first synthesized signal An extraction unit that extracts a transmission signal for each subcarrier included in the first transmission signal and extracts a transmission signal for each subcarrier included in the second transmission signal from the sampled second combined signal; A first phase difference calculation unit that calculates a phase delay for each subcarrier of the second transmission signal with respect to the first transmission signal, from the transmission signal for each subcarrier included and the transmission signal for each subcarrier included in the second transmission signal. And a skew calculator that calculates a skew between the first transmitter and the second transmitter based on the phase delay calculated by the first phase difference calculator. To provide a location.

  According to a third aspect of the present invention, there is provided a measurement method for measuring a carrier frequency phase difference between a plurality of transmitters that transmit a data signal in parallel using a plurality of subcarriers. A first transmission control stage in which a first transmission signal obtained by modulating a first data signal by a subcarrier not overlapping with a subcarrier used for transmission by a transmitter other than one transmitter is transmitted from the first transmitter; and at a second timing, A second transmission signal obtained by modulating the first data signal by the subcarrier is transmitted from the second transmitter in a state where transmission by the subcarrier used for transmission of the first transmission signal is not performed by a transmitter other than the second transmitter. A second transmission control stage, a first combined signal obtained by combining a plurality of transmission signals transmitted in parallel from a plurality of transmitters at a first timing, and a second timing; A synthesis stage for outputting a second synthesized signal obtained by synthesizing a plurality of transmission signals transmitted in parallel from a plurality of transmitters; a sampling stage for sampling each of the first synthesized signal and the second synthesized signal; Extracting a transmission signal for each subcarrier included in the first transmission signal from the first combined signal, and extracting a transmission signal for each subcarrier included in the second transmission signal from the sampled second combined signal; Calculating a phase delay for each subcarrier of the second transmission signal relative to the first transmission signal from the transmission signal for each subcarrier included in the first transmission signal and the transmission signal for each subcarrier included in the second transmission signal; 1 phase difference calculation stage and a carrier frequency between the first transmitter and the second transmitter based on the phase delay calculated in the first phase difference calculation stage To provide a measuring method and a calculation step the carrier frequency phase difference to calculate a phase difference.

  According to a fourth aspect of the present invention, there is provided a measurement method for measuring a skew between a plurality of transmitters that transmit data signals in parallel using a plurality of subcarriers, wherein the first transmitter is at a first timing. In a first transmission control stage in which a first transmission signal in which a first data signal is modulated by a subcarrier that does not overlap with a subcarrier used for transmission by a transmitter other than the first transmitter is transmitted from the first transmitter; Second transmission in which a second transmission signal obtained by modulating the first data signal by the subcarrier is transmitted from the second transmitter in a state where transmission by the subcarrier used for transmission of the first transmission signal is not performed by a transmitter other than the transmitter. A control stage, a first combined signal obtained by combining a plurality of transmission signals transmitted in parallel from a plurality of transmitters at a first timing, and a plurality of transmission signals at a second timing; A synthesis stage for outputting a second synthesized signal obtained by synthesizing a plurality of transmission signals transmitted in parallel from the transmitter, a sampling stage for sampling the first synthesized signal and the second synthesized signal, respectively, and the sampled first synthesized signal An extraction step of extracting a transmission signal for each subcarrier included in the first transmission signal from the sampled second combined signal, and extracting a transmission signal for each subcarrier included in the second transmission signal from the sampled second combined signal; Calculating a phase delay for each subcarrier of the second transmission signal relative to the first transmission signal from the transmission signal for each subcarrier included in the transmission signal and the transmission signal for each subcarrier included in the second transmission signal. And a skew for calculating a skew between the first transmitter and the second transmitter based on the phase delay calculated in the first phase difference calculating step To provide a measuring method and a step out.

  According to a fifth aspect of the present invention, there is provided a measurement program for operating a computer as a measurement apparatus that measures a carrier frequency phase difference between a plurality of transmitters that transmit data signals in parallel using a plurality of subcarriers. The computer causes the first transmitter to transmit, from the first transmitter, a first transmission signal obtained by modulating the first data signal using a subcarrier that does not overlap with a subcarrier used for transmission by a transmitter other than the first transmitter at the first timing. The first data signal is modulated by the subcarrier in a state in which transmission by the subcarrier used for transmission of the first transmission signal by the transmitter other than the second transmitter is not performed at one transmission control unit and the second timing. A second transmission control unit for transmitting two transmission signals from the second transmitter and a plurality of transmitters transmitted in parallel at the first timing A synthesis unit that outputs a first synthesized signal obtained by synthesizing a plurality of transmission signals and a second synthesized signal obtained by synthesizing a plurality of transmission signals transmitted in parallel from a plurality of transmitters at a second timing; And a sampling section for sampling each of the second combined signals, a transmission signal for each subcarrier included in the first transmission signal is extracted from the sampled first combined signal, and the second transmission signal is extracted from the sampled second combined signal An extraction unit that extracts a transmission signal for each subcarrier included in the transmission signal, a transmission signal for each subcarrier included in the first transmission signal, and a transmission signal for each subcarrier included in the second transmission signal. A first phase difference calculator that calculates a phase delay for each subcarrier of the second transmission signal with respect to the first phase difference, and a first phase difference calculated by the first phase difference calculator Shin unit and the second measurement program to function as the carrier frequency phase difference calculator for calculating a carrier frequency phase difference between the transmitter and to provide a recording medium which records the measurement program.

  According to a sixth aspect of the present invention, there is provided a measurement program for operating a computer as a measurement device that measures skew between a plurality of transmitters that transmit data signals in parallel using a plurality of subcarriers. First transmission control for transmitting a first transmission signal obtained by modulating a first data signal by a subcarrier not overlapping with a subcarrier used for transmission by a transmitter other than the first transmitter at a first timing The second transmission signal obtained by modulating the first data signal by the subcarrier in a state in which transmission by the subcarrier used for transmission of the first transmission signal is not performed by a transmitter other than the second transmitter at the second timing. A second transmission control unit for transmitting from the second transmitter, and a plurality of transmission signals transmitted in parallel from the plurality of transmitters at the first timing; A synthesis unit that outputs the synthesized first synthesized signal and a second synthesized signal obtained by synthesizing a plurality of transmission signals transmitted in parallel from a plurality of transmitters at a second timing; a first synthesized signal and a second synthesized signal; A sampling section for sampling each of the subcarriers included in the first transmission signal, and a subcarrier included in the second transmission signal from the sampled second composite signal. A second transmission signal for the first transmission signal from an extraction unit that extracts each transmission signal, a transmission signal for each subcarrier included in the first transmission signal, and a transmission signal for each subcarrier included in the second transmission signal A first phase difference calculation unit that calculates a phase delay for each subcarrier, and a first transmitter and a first phase difference based on the phase delay calculated by the first phase difference calculation unit Measurement program to function as the skew calculation unit for calculating a skew between the transmitter and to provide a recording medium which records the measurement program.

  The above summary of the invention does not enumerate all the necessary features of the present invention, and sub-combinations of these feature groups can also be the invention.

The structure of the measuring apparatus 20 which concerns on embodiment of this invention is shown with the structure of the to-be-measured apparatus 10. FIG. An example of the transmission signal output from the 1st transmitter 11 and the 2nd transmitter 12 is shown. An example of the synthesized signal synthesized by the synthesis unit 33 is shown. An example of the phase difference with respect to each subcarrier frequency is shown. The flowchart of the carrier frequency phase difference measurement process by the measuring apparatus 20 is shown. The structure of the measuring apparatus 20 which concerns on the 1st modification of this embodiment is shown with the structure of the to-be-measured apparatus 10. FIG. The flowchart of the skew measurement process by the measuring apparatus 20 which concerns on the 1st modification of this embodiment is shown. The structure of the measuring apparatus 20 which concerns on the 2nd modification of this embodiment is shown with the structure of the to-be-measured apparatus 10. FIG. The transmission signal output from the 1st transmitter 11 and the 2nd transmitter 12 which were controlled by the 1st transmission control part 31 and the 2nd transmission control part 32 which concern on the 3rd modification of this embodiment is shown. An example of the phase difference with respect to each subcarrier frequency measured by the measuring apparatus 20 which concerns on the 3rd modification of this embodiment is shown. 2 shows an exemplary hardware configuration of a computer 1900 according to an embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Device under test 11 1st transmitter 12 2nd transmitter 20 Measuring device 31 1st transmission control part 32 2nd transmission control part 33 Combining part 34 Sampling part 35 Synthetic signal memory | storage part 36 Extraction part 41 1st DFT memory 42 2nd DFT Memory 43 Third DFT memory 44 Fourth DFT memory 45 First phase difference calculation unit 46 Second phase difference calculation unit 47 Skew calculation unit 48 Carrier frequency phase difference calculation unit 51 First output terminal 52 Second output terminal 53 First input terminal 54 Second input terminal 61 First change rate calculation unit 62 Second change rate calculation unit 63 Calculation unit 71 Intercept calculation unit 72 Phase difference output unit 81 Inclination calculation unit 82 Skew output unit 1900 Computer 2000 CPU
2010 ROM
2020 RAM
2030 Communication interface 2040 Hard disk drive 2050 Flexible disk drive 2060 CD-ROM drive 2070 Input / output chip 2075 Graphic controller 2080 Display device 2082 Host controller 2084 Input / output controller 2090 Flexible disk 2095 CD-ROM

  Hereinafter, the present invention will be described through embodiments of the invention. However, the following embodiments do not limit the claimed invention, and all combinations of features described in the embodiments are invented. It is not always essential to the solution.

  FIG. 1 shows a configuration of a measuring apparatus 20 according to the present embodiment, together with a configuration of a device under measurement 10. The device under measurement 10 includes a first transmitter 11 and a second transmitter 12 that transmit an Orthogonal Division Multiplexing (OFDM) signal. The measuring device 20 measures a carrier frequency phase difference between a plurality of transmitters. The measuring device 20 measures the carrier frequency phase difference between the first transmitter 11 and the second transmitter 12, for example. A carrier frequency phase difference between a plurality of transmitters refers to a phase difference between carrier signals of the respective transmitters.

  The OFDM signal is an example of a transmission signal according to the present invention. The first transmitter 11 and the second transmitter 12 are an example of a transmitter according to the present invention. That is, the first transmitter 11 and the second transmitter 12 are an example of a plurality of transmitters that transmit data signals in parallel using a plurality of subcarriers. Further, the measuring device 20 may measure the carrier frequency phase difference between transmitters provided in different devices, instead of measuring the carrier frequency phase difference between a plurality of measuring devices provided in one device. Good. The measuring apparatus 20 is not limited to the measurement of the carrier frequency phase difference between two transmitters, and may measure the carrier frequency phase difference between three or more transmitters.

  The device under measurement 10 includes a first transmission control unit 31, a second transmission control unit 32, a synthesis unit 33, a sampling unit 34, a synthesized signal storage unit 35, an extraction unit 36, a first DFT memory 41, The second DFT memory 42, the third DFT memory 43, the fourth DFT memory 44, the first phase difference calculation unit 45, the second phase difference calculation unit 46, and the carrier frequency phase difference calculation unit 48 are provided, and the carrier is efficiently provided. Measure the frequency phase difference.

  The first transmission control unit 31 transmits a control signal to the first transmitter 11 and the second transmitter 12 via the first output terminal 51, thereby the first transmitter 11 and the second transmitter 12. From each of these, the OFDM signal at the first timing is transmitted. More specifically, the first transmission control unit 31 converts the first OFDM signal obtained by modulating the first data signal with subcarriers that do not overlap with subcarriers used for transmission by transmitters other than the first transmitter 11 at the first timing. 1 Transmit from the transmitter 11. In addition, at the first timing, the first transmission control unit 31 transmits transmitters other than the second transmitter 12 in parallel with the first transmitter 11 transmitting the first OFDM signal by two or more subcarriers. However, the second transmitter 12 may transmit a third transmission signal obtained by modulating the second data signal using two or more subcarriers not used for transmission.

  The second transmission control unit 32 transmits a control signal to the first transmitter 11 and the second transmitter 12 via the second output terminal 52, thereby the first transmitter 11 and the second transmitter 12. A predetermined OFDM signal at the second timing is transmitted from each of the above. More specifically, the second transmission control unit 32 performs the first transmission by the subcarrier in a state in which transmission by the subcarrier used for transmission of the first OFDM signal is not performed by the transmitter other than the second transmitter 12 at the second timing. A second OFDM signal obtained by modulating the data signal is transmitted from the second transmitter 12. In addition, the second transmission control unit 32 transmits transmitters other than the first transmitter 11 in parallel with the second transmitter 12 transmitting the second OFDM signal by two or more subcarriers at the second timing. However, the first transmitter 11 may transmit a fourth transmission signal obtained by modulating the second data signal using two or more subcarriers not used for transmission.

  The synthesizer 33 inputs the OFDM signal output from the first transmitter 11 via the first input terminal 53 and inputs the OFDM signal output from the second transmitter 12 via the second input terminal 54. To do. More specifically, the combining unit 33 combines the first combined signal obtained by combining a plurality of OFDM signals transmitted in parallel from the first transmitter 11 and the second transmitter 12 at the first timing, and the first transmission at the second timing. And a second combined signal obtained by combining a plurality of transmission signals transmitted in parallel from the transmitter 11 and the second transmitter 12. For example, the combining unit 33 may combine the plurality of input OFDM signals by adding them.

  The sampling unit 34 receives the synthesized signal output from the synthesizing unit 33, and samples the input synthesized signal by performing analog-digital conversion according to a sampling clock having a predetermined frequency. More specifically, the sampling unit 34 samples the first synthesized signal and the second synthesized signal, respectively. The synthesized signal storage unit 35 stores the first synthesized signal and the second synthesized signal sampled by the sampling unit 34.

  The extraction unit 36 performs discrete Fourier transform such as fast Fourier transform on the first synthesized signal and the second synthesized signal stored in the synthesized signal storage unit 35, and each subcarrier of the first synthesized signal and the second synthesized signal. The transmission signal that is modulated in (1) is extracted. More specifically, the extraction unit 36 extracts a transmission signal for each subcarrier included in the first OFDM signal from the sampled first combined signal, and extracts each transmission signal for each subcarrier included in the second OFDM signal from the sampled second combined signal. The transmitted signal is extracted. In addition, the extraction unit 36 extracts a transmission signal for each subcarrier included in the third OFDM signal from the sampled first combined signal, and subcarriers included in the fourth OFDM signal from the sampled second combined signal. Each transmission signal may be extracted.

  The first DFT memory 41, the second DFT memory 42, the third DFT memory 43, and the fourth DFT memory 44 store the transmission signal for each subcarrier extracted by the extraction unit 36. The first DFT memory 41 stores the transmission signal transmitted as the first OFDM signal at the first timing for each subcarrier. The second DFT memory 42 stores the transmission signal transmitted as the second OFDM signal at the second timing for each subcarrier. The third DFT memory 43 stores the transmission signal transmitted as the third OFDM signal at the first timing for each subcarrier. The fourth DFT memory 44 stores the transmission signal transmitted as the fourth OFDM signal at the second timing for each subcarrier.

  The first phase difference calculation unit 45 transmits each subcarrier included in the first OFDM signal stored in the first DFT memory 41 and each subcarrier included in the second OFDM signal stored in the second DFT memory 42. The phase delay for each subcarrier of the second OFDM signal with respect to the first OFDM signal is calculated from the signal. The second phase difference calculation unit 46 transmits each subcarrier included in the third OFDM signal stored in the third DFT memory 43 and each subcarrier included in the fourth OFDM signal stored in the fourth DFT memory 44. From the signal, the phase delay for each subcarrier of the third OFDM signal relative to the fourth OFDM signal is calculated.

  The carrier frequency phase difference calculator 48 calculates a carrier frequency phase difference between the first transmitter 11 and the second transmitter 12 based on the phase delay calculated by the first phase difference calculator 45. In addition, the carrier frequency phase difference calculator 48 calculates the carrier frequency phase difference between the first transmitter 11 and the second transmitter 12 based on the phase delay calculated by the second phase difference calculator 46. You can do it.

  As an example, the carrier frequency phase difference calculation unit 48 may include an intercept calculation unit 71 and a phase difference output unit 72. The intercept calculation unit 71 has an angular frequency of 0 based on at least one of the phase delay for each subcarrier calculated by the first phase difference calculation unit 45 or the phase delay for each subcarrier calculated by the second phase difference calculation unit 46. The phase delay corresponding to the subcarrier is calculated. The phase difference output unit 72 outputs the phase delay corresponding to the subcarrier whose angular frequency is 0 calculated by the intercept calculation unit 71 as the carrier frequency phase difference.

  According to the measuring device 20, the transmission signal is extracted for each subcarrier by discrete Fourier transform, and the extracted transmission signals are respectively compared in phase. Therefore, the carrier frequency phase difference can be calculated efficiently without using an oscilloscope or the like. The carrier frequency phase difference can be easily calculated even when the carrier frequency is high. Moreover, according to the measuring apparatus 20, since the OFDM signal transmitted in parallel from a plurality of transmitters is combined and the carrier frequency phase difference is measured, one measurement channel can be provided regardless of the number of transmitters. .

  FIG. 2 shows an example of transmission signals output from the first transmitter 11 and the second transmitter 12. The first transmission control unit 31 causes the first transmitter 11 to transmit the first OFDM signal at the first timing, and then the second transmission control unit 32 performs the first transmitter at the second timing after the first timing. 11 transmits the fourth OFDM signal. Further, the first transmission control unit 31 causes the second transmitter 12 to transmit the third OFDM signal at the first timing, and then the second transmission control unit 32 causes the second transmitter 12 to transmit the second OFDM signal at the second timing. Send a signal.

  As an example, the first transmission control unit 31 is configured such that the values of the I signal and the Q signal are predetermined for each of even-numbered subcarriers (hereinafter referred to as even subcarriers) among all the subcarriers. 1 data signal is modulated, and a signal of DC level (signal level is 0 for both IQ) is modulated to each of odd-numbered subcarriers (hereinafter referred to as odd subcarriers), and a guard interval (GI of a predetermined length) ) Is added to the first transmitter 11. Then, the first transmission control unit 31 outputs the generated first OFDM signal from the first transmitter 11 at the first timing. Equation (1) below shows the first OFDM signal.

In Equation (1), t, Tx1 _Symbol1 (t), ω _C , ω _{n, e} , ξ _{n, e} mean the following contents. The same applies to equation (2) and thereafter.
t: Time Tx1 _Symbol1 (t): First OFDM signal ω _C transmitted by the first transmitter 11 at the first timing: Angular frequency ω _{n, e of} carrier signal ξ _{n, e} : Even angular frequency of even subcarrier Subcarrier phase

  In addition, as an example, the first transmission control unit 31 modulates the second data signal in which the values of the I signal and the Q signal are predetermined for each of the odd subcarriers, and the DC level for each of the even subcarriers. The second transmitter 12 generates a third OFDM signal to which a predetermined length of GI is added. Then, the first transmission control unit 31 outputs the generated third OFDM signal from the second transmitter 12 at the first timing. Equation (2) below shows the third OFDM signal.

In Expression (2), Tx2 _Symbol1 (t), ω _{n, o} , ξ _{n, o} , Δτ, and Δθ mean the following contents. The same applies to equations (3) and thereafter.
Tx2 _Symbol1 (t): Third OFDM signal ω _{n, o} transmitted by the second transmitter 12 at the first timing: Angular frequency of an odd subcarrier ξ _{n, o} : Phase of an odd subcarrier Δτ: First transmitter 11 Δθ between the first transmitter 11 and the second transmitter 12: carrier frequency phase difference between the first transmitter 11 and the second transmitter 12

  Further, as an example, the second transmission control unit 32 modulates the second data signal for each odd subcarrier and modulates a DC level signal for each even subcarrier to obtain a predetermined length of GI. The added fourth OFDM signal is generated by the first transmitter 11. Then, the second transmission control unit 32 causes the first transmitter 11 to output the generated fourth OFDM signal at the second timing. Equation (3) below shows the fourth OFDM signal.

In the formula _{(3), Tx1 Symbol2 (t} ), Δt 2 means the following:. The same applies to equation (4) and thereafter.
Tx1 _Symbol2 (t): the fourth OFDM signal Δt ₂ transmitted by the first transmitter 11 at the second timing: time difference between the first timing and the second timing

  Further, as an example, the second transmission control unit 32 modulates the first data signal for each of the even subcarriers, and modulates the DC level signal for each of the odd subcarriers to obtain a predetermined length of GI. The second transmitter 12 is caused to generate the added second OFDM signal. Then, the second transmission control unit 32 causes the second transmitter 12 to output the generated second OFDM signal at the second timing. Equation (4) below shows the second OFDM signal.

In Expression (4), Tx2 _Symbol2 (t) means the following content.
Tx2 _Symbol2 (t): the second OFDM signal transmitted by the second transmitter 12 at the second timing

  As described above, according to the measurement apparatus 20, the signal is modulated between the first OFDM signal transmitted from the first transmitter 11 and the third OFDM signal transmitted from the second transmitter 12 at the first timing. Transmission control can be performed so that existing subcarriers do not overlap. Similarly, according to the measuring apparatus 20, at the second timing, the sub-modulation of the signal between the fourth OFDM signal transmitted from the first transmitter 11 and the second OFDM signal transmitted from the second transmitter 12 is performed. Transmission control can be performed so that carriers do not overlap. Thereby, according to the measuring apparatus 20, since the signal transmitted from two transmitters can be added and combined and processed, the carrier frequency phase difference can be measured by one measurement channel.

  FIG. 3 shows an example of the synthesized signal synthesized by the synthesis unit 33. The synthesizer 33 adds the first OFDM signal whose signal is modulated to the even subcarrier and the third OFDM signal whose signal is modulated to the odd subcarrier at the first timing, and the signal is modulated to all subcarriers. The first synthesized signal is generated. In addition, at the second timing, the combining unit 33 adds the fourth OFDM signal whose signal is modulated to the odd subcarrier and the second OFDM signal whose signal is modulated to the even subcarrier, so that the signal is transmitted to all the subcarriers. The modulated second synthesized signal is output.

  The extraction unit 36 performs a discrete Fourier operation (DFT) on each of the first synthesized signal and the second synthesized signal. The extraction unit 36 performs a discrete Fourier transform on the calculation range obtained by subtracting the GI length from one symbol length. The extraction unit 36 cuts out the calculation range from the position delayed by the same time (Δx) from the symbol start position (for example, the center position of the GI) for each of the first synthesized signal and the second synthesized signal, Perform discrete Fourier transform. Thereby, the extraction part 36 can eliminate the phase shift between the 1st synthetic signal and the 2nd synthetic signal accompanying discrete Fourier transform.

  The extraction unit 36 can extract transmission signals modulated on all subcarriers by performing discrete Fourier transform as described above. The extraction unit 36 separates the extracted transmission signal into a signal that has been modulated into even subcarriers and a signal that has been modulated into odd subcarriers, and stores them in the corresponding memory among the first DFT memory 41 to the fourth DFT memory 44. Remember each one.

  FIG. 4 shows an example of the phase difference for each subcarrier frequency. The first phase difference calculation unit 45 calculates the phase difference of the second OFDM signal with respect to the first OFDM signal for each subcarrier. The first OFDM signal is modulated to an even subcarrier at the first timing, and the second OFDM signal is modulated to an even subcarrier at the second timing. Further, the first data signal is modulated in both the first OFDM signal and the second OFDM signal. That is, the first OFDM signal and the second OFDM signal are modulated in the same phase. Therefore, the first phase difference calculation unit 45 can detect the phase delay of the second OFDM signal with respect to the first OFDM signal by detecting the phase difference between the transmission signals (IQ signals) extracted for each subcarrier. Further, as shown in the following formula (5), the first phase difference calculation unit 45 can detect the phase delay by complex-dividing the extracted signal and obtaining the declination angle.

  The second phase difference calculation unit 46 calculates the phase difference of the third OFDM signal with respect to the fourth OFDM signal. Similarly, in the third OFDM signal and the fourth OFDM signal, the same signal (second data signal) is modulated to the same subcarrier (odd subcarrier). Therefore, the second phase difference calculation unit 46 can detect the phase delay of the third OFDM signal with respect to the fourth OFDM signal. Further, as shown in the following formula (6), the second phase difference calculation unit 46 can detect the phase difference by complex-dividing the extracted signal and obtaining the declination angle.

  Then, the carrier frequency phase difference calculation unit 48 calculates the phase delay (Δθ) corresponding to the subcarrier whose angular frequency is 0, based on at least one of the calculated expressions (5) and (6). As an example, the carrier frequency phase difference calculation unit 48 approximates a straight line representing a phase delay with respect to the subcarrier angular frequency based on at least one sample point of the calculated equations (5) and (6). Above, the phase delay (Δθ) at the point where the subcarrier angular frequency becomes 0 is calculated.

  According to the measuring apparatus 20, since the phase delay is obtained for each odd subcarrier and even subcarrier as described above, the carrier frequency phase difference can be calculated efficiently. Moreover, according to the measuring apparatus 20, the carrier frequency phase difference can be calculated with high resolution by setting the phase delay corresponding to the subcarrier having the angular frequency of 0 as the carrier frequency phase difference. Moreover, according to the measuring apparatus 20, by calculating the carrier frequency phase difference based on the phase delay, it is possible to calculate an accurate carrier frequency phase difference excluding the frequency characteristics.

Here, the frequency characteristic of the measurement device 20 is A (ω _n ), the signal output from the first transmitter 11 is Q ₁ (ω _n ), and the signal output from the second transmitter 12 is Q _2. If the _{(ω n), Q 1 (} ω n) signal _{R 1} to the measuring apparatus 20 receives the (omega _n) is represented by the following formula _{(7), Q 2 (ω} n) of the measuring device 20 is received The signal R ₂ (ω _n ) is expressed by the following equation (8).

The first phase difference calculation unit 45 and the second phase difference calculation unit 46 indicate the phase delay of the second OFDM signal with respect to the first OFDM signal and the phase delay of the third OFDM signal with respect to the fourth OFDM signal, as shown in the following equation (9): The reception signal R ₂ (ω _n ) of the second transmitter 12 is divided by the reception signal R ₁ (ω _n ) of the first transmitter 11 to calculate the deflection angle. Therefore, the first phase difference calculation unit 45 and the second phase difference calculation unit 46 can remove the frequency characteristic A (ω _n ) of the measurement device 20 in obtaining the phase delay. Thus, according to the measuring device 20, an accurate carrier frequency phase difference can be calculated regardless of the frequency characteristics of the measuring device 20.

  FIG. 5 shows a flowchart of the carrier frequency phase difference measurement process by the measurement apparatus 20. First, the first transmission control unit 31 causes the first transmitter 11 to transmit the first OFDM signal and the second transmitter 12 to transmit the third OFDM signal at the first timing (S11). Next, the combining unit 33 combines the transmitted first OFDM signal and the third OFDM signal to generate a first combined signal, and then the sampling unit 34 samples the first combined signal, and then combines them. The signal storage unit 35 stores the sampled first combined signal (S12).

  Next, the second transmission control unit 32 causes the first transmitter 11 to transmit the fourth OFDM signal and the second transmitter 12 to transmit the second OFDM signal at the second timing (S13). Next, the synthesizer 33 synthesizes the transmitted fourth OFDM signal and the second OFDM signal to generate a second synthesized signal. Subsequently, the sampling unit 34 samples the second synthesized signal, and then synthesizes the second synthesized signal. The signal storage unit 35 stores the sampled second composite signal (S14).

  Next, the extraction unit 36 performs a discrete Fourier transform on the first combined signal and the second combined signal, and extracts a transmission signal modulated on each subcarrier from each (S15). Next, the first phase difference calculation unit 45 calculates the phase difference for each subcarrier of the second OFDM signal with respect to the first OFDM signal based on the result extracted in step S15 (S16). Next, the second phase difference calculation unit 46 calculates the phase difference for each subcarrier of the fourth OFDM signal with respect to the third OFDM signal based on the result extracted in step S15 (S17). Then, the carrier frequency phase difference calculation unit 48 calculates the carrier frequency phase difference between the first transmitter 11 and the second transmitter 12 based on the phase difference calculated in step S16 and step S17 (S18).

  FIG. 6 shows the configuration of the measuring apparatus 20 according to the first modification of the present embodiment, together with the configuration of the device under measurement 10. FIG. 7 shows a flowchart of skew measurement processing by the measuring apparatus 20 according to the first modification of the present embodiment. Note that the measurement apparatus 20 according to the present modification employs substantially the same function and configuration as the measurement apparatus 20 shown in FIG. 1, and therefore the description thereof will be omitted except for the difference from the measurement apparatus 20 shown in FIG. 1.

  The measuring apparatus 20 according to the first modification measures the skew between the first transmitter 11 and the second transmitter 12. The skew between a plurality of transmitters refers to the time difference between the output delays of the signals output from the respective transmitters. Note that the measuring apparatus 20 may measure the skew between transmitters provided in different devices, instead of measuring the skew between a plurality of measuring devices provided in one device. The measuring apparatus 20 is not limited to measuring the skew between two transmitters, and may measure the skew between three or more transmitters.

  The measurement apparatus 20 includes a skew calculation unit 47 instead of the carrier frequency phase difference calculation unit 48. The skew calculation unit 47 calculates the skew between the first transmitter 11 and the second transmitter 12 based on the phase delay calculated by the first phase difference calculation unit 45. In addition to this, the skew calculator 47 may calculate the skew between the first transmitter 11 and the second transmitter 12 based on the phase delay calculated by the second phase difference calculator 46.

  Further, the measuring device 20 performs the process of step S19 shown in FIG. 7 instead of the process of step S18 shown in FIG. In step S19, the skew calculation unit 47 calculates the skew between the first transmitter 11 and the second transmitter 12 based on the phase difference calculated in steps S16 and S17 (S19).

  According to such a measuring apparatus 20, a transmission signal is extracted for each subcarrier by discrete Fourier transform, and the extracted transmission signals are phase-compared. Therefore, the skew can be calculated efficiently without using an oscilloscope or the like. The skew can be easily calculated even when the carrier frequency is high. Moreover, according to the measuring apparatus 20, since the skew is measured by combining OFDM signals transmitted in parallel from a plurality of transmitters, one measurement channel can be provided regardless of the number of transmitters.

  Moreover, the skew calculation part 47 may have the 1st change rate calculation part 61, the 2nd change rate calculation part 62, and the calculating part 63 as an example.

The first rate-of-change calculator 61 calculates a first rate of change, which is the rate of change of the phase delay with respect to the angular frequency of the subcarrier, from the phase delay of each subcarrier of the second OFDM signal with respect to the first OFDM signal. That is, the first rate-of-change calculator 61 calculates the first rate of change Δθ _{n, e} / which is the rate of change of the phase θ _{n, e with} respect to the angular frequency ω _{n, e} of the even subcarrier based on the above equation (5). Δω _{n, e} is calculated. In other words, the first change rate calculation unit 61 calculates the slope of the phase θ _{n, e} . Instead of this, the first rate-of-change calculator 61 calculates a first rate of change, which is a rate of change of the phase delay with respect to the angular frequency of the subcarrier, from the phase delay of each subcarrier of the first OFDM signal with respect to the second OFDM signal. It may be calculated.

The second rate-of-change calculator 62 calculates a second rate of change, which is the rate of change of the phase with respect to the angular frequency of the subcarrier, from the phase delay for each subcarrier of the third OFDM signal with respect to the fourth OFDM signal. That is, the second rate-of-change calculator 62 calculates the second rate of change Δθ _{n, o} / _, which is the rate of change of the phase θ _{n, o with} respect to the angular frequency ω _{n, o} of the odd subcarrier, based on the above equation (6). Δω _{n, o} is calculated. That is, the second change rate calculation unit 62 calculates the gradient of the phase θ _{n, o} . Instead of this, the second rate-of-change calculator 62 calculates the second rate of change, which is the rate of change of the phase delay with respect to the angular frequency of the subcarrier, from the phase delay of each subcarrier of the fourth OFDM signal with respect to the third OFDM signal. It may be calculated.

The computing unit 63 removes the time difference (Δt ₂ ) between the first timing and the second timing by adding or subtracting the first change rate and the second change rate, and the time difference between the first timing and the second timing ( The skew is calculated by dividing the addition result or the subtraction result from which Δt ₂ ) is removed by 2.

  For example, the calculation unit 63 has a first change rate as a change rate of a phase delay for each subcarrier of the second OFDM signal with respect to the first OFDM signal, and a second change rate as a subcarrier of the fourth OFDM signal with respect to the third OFDM signal. For each phase delay change rate, the skew may be calculated by dividing the difference between the first change rate and the second change rate by two. Further, as an example, the calculation unit 63 has a first change rate that is a change rate of a phase delay for each subcarrier of the second OFDM signal with respect to the first OFDM signal, and a second change rate that of the third OFDM signal with respect to the fourth OFDM signal. In the case of the change rate of the phase delay for each subcarrier, the skew may be calculated by dividing the sum of the first change rate and the second change rate by 2.

  The computing unit 63 also has a first rate of change of the phase delay for each subcarrier of the first OFDM signal relative to the second OFDM signal, and a second rate of change for each subcarrier of the fourth OFDM signal relative to the third OFDM signal. In this case, the skew may be calculated by dividing the sum of the first change rate and the second change rate by two. In addition, the calculation unit 63 has a first change rate that is a change rate of a phase delay for each subcarrier of the first OFDM signal with respect to the second OFDM signal, and a second change rate that is set for each subcarrier of the third OFDM signal with respect to the fourth OFDM signal. In this case, the skew may be calculated by dividing the difference between the first change rate and the second change rate by two.

  According to the measuring apparatus 20, since the change rate of the phase characteristic is obtained for each odd subcarrier and even subcarrier as described above, the skew can be calculated efficiently. Further, according to the measuring apparatus 20, the skew can be calculated with high resolution by calculating the skew based on the change rate of the phase delay. Moreover, according to the measuring apparatus 20, by obtaining the skew based on the difference in the change rate of the phase delay, it is possible to calculate an accurate skew that excludes the frequency characteristics.

  FIG. 8 shows the configuration of the measuring apparatus 20 according to the second modification of the present embodiment, together with the configuration of the device under measurement 10. Note that the measurement apparatus 20 according to the present modification employs substantially the same function and configuration as the measurement apparatus 20 shown in FIG. 1, and therefore the description thereof will be omitted except for the difference from the measurement apparatus 20 shown in FIG. 1.

  The measuring apparatus 20 according to this modification further includes a skew calculation unit 47. The skew calculation unit 47 has the same configuration and function as the skew calculation unit 47 shown in FIG. Thereby, according to the measuring apparatus 20 which concerns on this modification, both a carrier frequency phase error and a skew can be calculated efficiently.

  FIG. 9 shows transmission signals output from the first transmitter 11 and the second transmitter 12 controlled by the first transmission control unit 31 and the second transmission control unit 32 according to the third modification of the present embodiment. . Note that the measurement apparatus 20 according to the present modification employs substantially the same function and configuration as the measurement apparatus 20 shown in FIG. 1, and therefore the description thereof will be omitted except for the difference from the measurement apparatus 20 shown in FIG. 1.

In the present modification, the second transmission control unit 32 may cause the second transmitter 12 to transmit the second OFDM signal at the second timing delayed from the first timing by multiplying the symbol period by a positive integer. In addition to this, the second transmission control unit 32 may cause the first transmitter 11 to transmit the fourth OFDM signal at a second timing delayed from the first timing by multiplying the symbol period by a positive integer. As an example, the second transmission control unit 32 may link the fourth OFDM signal transmitted at the second timing to the symbol immediately after the symbol of the first OFDM signal transmitted at the first timing. Similarly, the second transmission control unit 32 may connect the second OFDM signal transmitted at the second timing to the symbol immediately after the third OFDM signal transmitted at the first timing. By setting in this way, ω _n × Δt ₂ = 2π × k (k is an arbitrary integer), and therefore the time difference between the first timing and the second timing in Equation (5) and Equation (6). Δt2 may be 0.

  Furthermore, in this modification, the intercept calculation unit 71 calculates the angular frequency from the phase delay for each subcarrier of the second transmission signal with respect to the first transmission signal and the phase delay for each subcarrier of the third transmission signal with respect to the fourth transmission signal. The relationship with the phase delay may be approximated to a straight line, and the phase delay corresponding to the subcarrier having an angular frequency of 0 may be calculated based on the approximated straight line.

FIG. 10 shows an example of the phase difference for each subcarrier frequency measured by the measuring apparatus 20 according to the third modification. In the present modification, the time difference Δt ₂ between the first timing and the second timing is 0, so both the equations (5) and (6) are the same equation. In other words, the slopes of the phase delay of the second OFDM signal with respect to the first OFDM signal and the phase delay of the fourth OFDM signal with respect to the third OFDM signal with respect to the angular frequency of the subcarrier match. Therefore, the carrier frequency phase difference calculation unit 48 can approximate a straight line using both the phase delay of the second OFDM signal with respect to the first OFDM signal and the phase delay of the fourth OFDM signal with respect to the third OFDM signal. Thereby, according to the measuring apparatus 20 according to the present modification, the phase delay (Δθ: carrier phase frequency difference) corresponding to the subcarrier with the angular frequency of 0 is more accurately obtained using the phase delay of a large number of samples. Can be calculated.

When the time difference Δt ₂ between the first timing and the second timing is 0, the phase delay of the second OFDM signal with respect to the first OFDM signal or the fourth OFDM signal with respect to the third OFDM signal in the equations (5) and (6) The slope of the phase delay with respect to the subcarrier angular frequency is a skew (Δτ) between the first transmitter 11 and the second transmitter 12. Therefore, the skew calculation unit 47 approximates a straight line using at least one of the phase delay of the second OFDM signal relative to the first OFDM signal and the phase delay of the fourth OFDM signal relative to the third OFDM signal, and calculates the slope of the straight line. Thus, the skew can be obtained. Thereby, according to the measuring apparatus 20 which concerns on this modification, the skew between the 1st transmitter 11 and the 2nd transmitter 12 can be simply calculated using the phase delay of many samples. .

  FIG. 11 shows an example of a hardware configuration of a computer 1900 according to this embodiment. A computer 1900 according to this embodiment is connected to a CPU peripheral unit having a CPU 2000, a RAM 2020, a graphic controller 2075, and a display device 2080 that are connected to each other by a host controller 2082, and to the host controller 2082 by an input / output controller 2084. Input / output unit having communication interface 2030, hard disk drive 2040, and CD-ROM drive 2060, and legacy input / output unit having ROM 2010, flexible disk drive 2050, and input / output chip 2070 connected to input / output controller 2084 With.

  The host controller 2082 connects the RAM 2020 to the CPU 2000 and the graphic controller 2075 that access the RAM 2020 at a high transfer rate. The CPU 2000 operates based on programs stored in the ROM 2010 and the RAM 2020 and controls each unit. The graphic controller 2075 acquires image data generated by the CPU 2000 or the like on a frame buffer provided in the RAM 2020 and displays it on the display device 2080. Instead of this, the graphic controller 2075 may include a frame buffer for storing image data generated by the CPU 2000 or the like.

  The input / output controller 2084 connects the host controller 2082 to the communication interface 2030, the hard disk drive 2040, and the CD-ROM drive 2060, which are relatively high-speed input / output devices. The communication interface 2030 communicates with other devices via a network. The hard disk drive 2040 stores programs and data used by the CPU 2000 in the computer 1900. The CD-ROM drive 2060 reads a program or data from the CD-ROM 2095 and provides it to the hard disk drive 2040 via the RAM 2020.

  The input / output controller 2084 is connected to the ROM 2010, the flexible disk drive 2050, and the relatively low-speed input / output device of the input / output chip 2070. The ROM 2010 stores a boot program that the computer 1900 executes at startup, a program that depends on the hardware of the computer 1900, and the like. The flexible disk drive 2050 reads a program or data from the flexible disk 2090 and provides it to the hard disk drive 2040 via the RAM 2020. The input / output chip 2070 connects various input / output devices via a flexible disk drive 2050 and, for example, a parallel port, a serial port, a keyboard port, a mouse port, and the like.

  A program provided to the hard disk drive 2040 via the RAM 2020 is stored in a recording medium such as the flexible disk 2090, the CD-ROM 2095, or an IC card and provided by the user. The program is read from the recording medium, installed in the hard disk drive 2040 in the computer 1900 via the RAM 2020, and executed by the CPU 2000.

  A program that is installed in the computer 1900 and causes the computer 1900 to function as the measuring device 20 includes a first transmission control module, a second transmission control module, a synthesis module, a sampling module, and a synthesized signal storage module. An extraction unit module, a first DFT memory module, a second DFT memory module, a third DFT memory module, a fourth DFT memory module, a first phase difference calculation unit module, a second phase difference calculation unit module, and a carrier frequency A phase difference calculation module. These programs or modules work on the CPU 2000 or the like to change the computer 1900 into the first transmission control unit 31, the second transmission control unit 32, the synthesis unit 33, the sampling unit 34, the synthesized signal storage unit 35, the extraction unit 36, the first Functions as a 1DFT memory 41, a second DFT memory 42, a third DFT memory 43, a fourth DFT memory 44, a first phase difference calculation unit 45, a second phase difference calculation unit 46, a skew calculation unit 47, and a carrier frequency phase difference calculation unit 48, respectively. Let

  The program or module shown above may be stored in an external storage medium. As the storage medium, in addition to the flexible disk 2090 and the CD-ROM 2095, an optical recording medium such as DVD or CD, a magneto-optical recording medium such as MO, a tape medium, a semiconductor memory such as an IC card, or the like can be used. Further, a storage device such as a hard disk or RAM provided in a server system connected to a dedicated communication network or the Internet may be used as a recording medium, and the program may be provided to the computer 1900 via the network.

  As mentioned above, although this invention was demonstrated using embodiment, the technical scope of this invention is not limited to the range as described in the said embodiment. It will be apparent to those skilled in the art that various modifications or improvements can be made to the above embodiment. It is apparent from the scope of the claims that the embodiments added with such changes or improvements can be included in the technical scope of the present invention.

Claims (15)

A measuring device for measuring a carrier frequency phase difference between a plurality of transmitters that transmit data signals in parallel using a plurality of subcarriers,
A first transmission control unit for transmitting, from the first transmitter, a first transmission signal obtained by modulating a first data signal by a subcarrier not overlapping with a subcarrier used for transmission by a transmitter other than the first transmitter at a first timing. When,
At a second timing, a second transmission signal obtained by modulating the first data signal by the subcarrier is transmitted in a state where transmission by the subcarrier used for transmission of the first transmission signal is not performed by a transmitter other than the second transmitter. A second transmission control unit for transmitting from the second transmitter;
A first combined signal obtained by combining a plurality of transmission signals transmitted in parallel from the plurality of transmitters at a first timing and a plurality of transmission signals transmitted in parallel from the plurality of transmitters at a second timing. A combining unit that outputs a second combined signal;
A sampling unit for sampling each of the first synthesized signal and the second synthesized signal;
A transmission signal for each subcarrier included in the first transmission signal is extracted from the sampled first combined signal, and a transmission signal for each subcarrier included in the second transmission signal is extracted from the sampled second combined signal. An extraction unit for extracting
A phase delay for each subcarrier of the second transmission signal with respect to the first transmission signal from a transmission signal for each subcarrier included in the first transmission signal and a transmission signal for each subcarrier included in the second transmission signal A first phase difference calculating unit for calculating
A measuring apparatus comprising: a carrier frequency phase difference calculating unit that calculates a carrier frequency phase difference between the first transmitter and the second transmitter based on the phase delay calculated by the first phase difference calculating unit. At the first timing, the first transmission control unit transmits a transmission other than the second transmitter in parallel with the first transmitter transmitting the first transmission signal using two or more subcarriers. A third transmission signal obtained by modulating the second data signal with two or more subcarriers not used in the transmission is transmitted from the second transmitter,
At the second timing, the second transmission control unit transmits, in parallel with the second transmitter transmitting the second transmission signal using two or more subcarriers, by a transmitter other than the first transmitter. A fourth transmission signal obtained by modulating the second data signal by two or more subcarriers not used in the transmission is transmitted from the first transmitter,
The extraction unit further extracts a transmission signal for each subcarrier included in the third transmission signal from the sampled first combined signal and includes the sampled second combined signal in the fourth transmission signal. Extract the transmitted signal for each subcarrier,
A phase delay for each subcarrier of the third transmission signal with respect to the fourth transmission signal from a transmission signal for each subcarrier included in the third transmission signal and a transmission signal for each subcarrier included in the fourth transmission signal A second phase difference calculation unit for calculating
The carrier frequency phase difference calculation unit includes a phase delay for each subcarrier of the second transmission signal with respect to the first transmission signal and a phase delay for each subcarrier of the third transmission signal with respect to the fourth transmission signal. The measurement apparatus according to claim 1, wherein a carrier frequency phase difference between the first transmitter and the second transmitter is calculated. The carrier frequency phase difference calculator is
Based on at least one of the phase delay for each subcarrier calculated by the first phase difference calculation unit or the phase delay for each subcarrier calculated by the second phase difference calculation unit, corresponding to a subcarrier having an angular frequency of 0 An intercept calculation unit for calculating the phase delay to be
The measurement apparatus according to claim 2, further comprising: a phase difference output unit that outputs, as the carrier frequency phase difference, a phase delay corresponding to a subcarrier having an angular frequency of 0 calculated by the intercept calculation unit. The second transmission control unit causes the second transmitter to transmit the second transmission signal at the second timing delayed from the first timing by multiplying a symbol period by a positive integer;
The intercept calculation unit includes an angular frequency and a phase delay from a phase delay for each subcarrier of the second transmission signal with respect to the first transmission signal and a phase delay for each subcarrier of the third transmission signal with respect to the fourth transmission signal. The measurement apparatus according to claim 3, wherein a phase delay corresponding to a subcarrier having an angular frequency of 0 is calculated based on the approximated straight line. The second transmission control unit causes the second transmitter to transmit the second transmission signal at the second timing delayed from the first timing by multiplying a symbol period by a positive integer;
The measurement apparatus according to claim 1, further comprising a skew calculation unit that calculates a skew between the first transmitter and the second transmitter based on the phase delay calculated by the first phase difference calculation unit. A measuring device that measures skew between a plurality of transmitters that transmit data signals in parallel using a plurality of subcarriers,
A first transmission control unit for transmitting, from the first transmitter, a first transmission signal obtained by modulating a first data signal by a subcarrier not overlapping with a subcarrier used for transmission by a transmitter other than the first transmitter at a first timing. When,
At a second timing, a second transmission signal obtained by modulating the first data signal by the subcarrier is transmitted in a state where transmission by the subcarrier used for transmission of the first transmission signal is not performed by a transmitter other than the second transmitter. A second transmission control unit for transmitting from the second transmitter;
A first combined signal obtained by combining a plurality of transmission signals transmitted in parallel from the plurality of transmitters at a first timing and a plurality of transmission signals transmitted in parallel from the plurality of transmitters at a second timing. A combining unit that outputs a second combined signal;
A sampling unit for sampling each of the first synthesized signal and the second synthesized signal;
A transmission signal for each subcarrier included in the first transmission signal is extracted from the sampled first combined signal, and a transmission signal for each subcarrier included in the second transmission signal is extracted from the sampled second combined signal. An extraction unit for extracting
A phase delay for each subcarrier of the second transmission signal with respect to the first transmission signal from a transmission signal for each subcarrier included in the first transmission signal and a transmission signal for each subcarrier included in the second transmission signal A first phase difference calculating unit for calculating
A measuring apparatus comprising: a skew calculating unit that calculates a skew between the first transmitter and the second transmitter based on the phase delay calculated by the first phase difference calculating unit. At the first timing, the first transmission control unit transmits a transmission other than the second transmitter in parallel with the first transmitter transmitting the first transmission signal using two or more subcarriers. A third transmission signal obtained by modulating the second data signal with two or more subcarriers not used in the transmission is transmitted from the second transmitter,
At the second timing, the second transmission control unit transmits, in parallel with the second transmitter transmitting the second transmission signal using two or more subcarriers, by a transmitter other than the first transmitter. A fourth transmission signal obtained by modulating the second data signal by two or more subcarriers not used in the transmission is transmitted from the first transmitter,
The extraction unit further extracts a transmission signal for each subcarrier included in the third transmission signal from the sampled first combined signal and includes the sampled second combined signal in the fourth transmission signal. Extract the transmitted signal for each subcarrier,
A phase delay for each subcarrier of the third transmission signal with respect to the fourth transmission signal from a transmission signal for each subcarrier included in the third transmission signal and a transmission signal for each subcarrier included in the fourth transmission signal A second phase difference calculation unit for calculating
The carrier frequency phase difference calculation unit includes a phase delay for each subcarrier of the second transmission signal with respect to the first transmission signal and a phase delay for each subcarrier of the third transmission signal with respect to the fourth transmission signal. The measurement apparatus according to claim 6, wherein a carrier frequency phase difference between the first transmitter and the second transmitter is calculated. The skew calculation unit
A first rate-of-change calculating unit that calculates a first rate of change that is a rate of change of the phase delay with respect to the angular frequency of the subcarrier from the phase delay of each subcarrier of the second transmitted signal with respect to the first transmitted signal;
A second rate-of-change calculating unit that calculates a second rate of change that is a rate of change of the phase with respect to the angular frequency of the subcarrier from the phase delay of each subcarrier of the fourth transmitted signal with respect to the third transmitted signal;
The measurement apparatus according to claim 7, further comprising: an arithmetic unit that calculates the skew by dividing a difference between the first change rate and the second change rate by two. The second transmission control unit causes the second transmitter to transmit the second transmission signal at the second timing delayed from the first timing by multiplying a symbol period by a positive integer;
The skew calculation unit calculates a change rate of a phase delay for each frequency of subcarriers from the phase delay for each subcarrier of the second transmission signal with respect to the first transmission signal, and sets the skew as the skew. Measuring device. A measurement method for measuring a carrier frequency phase difference between a plurality of transmitters that transmit data signals in parallel using a plurality of subcarriers,
A first transmission control stage in which a first transmission signal obtained by modulating a first data signal by a subcarrier not overlapping with a subcarrier used for transmission by a transmitter other than the first transmitter is transmitted from the first transmitter at a first timing; When,
At a second timing, a second transmission signal obtained by modulating the first data signal by the subcarrier is transmitted in a state where transmission by the subcarrier used for transmission of the first transmission signal is not performed by a transmitter other than the second transmitter. A second transmission control step for transmitting from the second transmitter;
A first combined signal obtained by combining a plurality of transmission signals transmitted in parallel from the plurality of transmitters at a first timing and a plurality of transmission signals transmitted in parallel from the plurality of transmitters at a second timing. A synthesis stage for outputting a second synthesized signal;
A sampling stage for sampling each of the first synthesized signal and the second synthesized signal;
A transmission signal for each subcarrier included in the first transmission signal is extracted from the sampled first combined signal, and a transmission signal for each subcarrier included in the second transmission signal is extracted from the sampled second combined signal. An extraction stage for extracting,
A phase delay for each subcarrier of the second transmission signal with respect to the first transmission signal from a transmission signal for each subcarrier included in the first transmission signal and a transmission signal for each subcarrier included in the second transmission signal A first phase difference calculating step for calculating
A carrier frequency phase difference calculating step of calculating a carrier frequency phase difference between the first transmitter and the second transmitter based on the phase delay calculated in the first phase difference calculating step. A measurement method for measuring a skew between a plurality of transmitters that transmit data signals in parallel using a plurality of subcarriers,
A first transmission control stage in which a first transmission signal obtained by modulating a first data signal by a subcarrier not overlapping with a subcarrier used for transmission by a transmitter other than the first transmitter is transmitted from the first transmitter at a first timing; When,
At a second timing, a second transmission signal obtained by modulating the first data signal by the subcarrier is transmitted in a state where transmission by the subcarrier used for transmission of the first transmission signal is not performed by a transmitter other than the second transmitter. A second transmission control step for transmitting from the second transmitter;
A first combined signal obtained by combining a plurality of transmission signals transmitted in parallel from the plurality of transmitters at a first timing and a plurality of transmission signals transmitted in parallel from the plurality of transmitters at a second timing. A synthesis stage for outputting a second synthesized signal;
A sampling stage for sampling each of the first synthesized signal and the second synthesized signal;
A transmission signal for each subcarrier included in the first transmission signal is extracted from the sampled first combined signal, and a transmission signal for each subcarrier included in the second transmission signal is extracted from the sampled second combined signal. An extraction stage for extracting,
A phase delay for each subcarrier of the second transmission signal with respect to the first transmission signal from a transmission signal for each subcarrier included in the first transmission signal and a transmission signal for each subcarrier included in the second transmission signal A first phase difference calculating step for calculating
A skew calculating step of calculating a skew between the first transmitter and the second transmitter based on the phase delay calculated in the first phase difference calculating step. A measurement program for operating a computer as a measurement device for measuring a carrier frequency phase difference between a plurality of transmitters that transmit data signals in parallel using a plurality of subcarriers,
The computer,
A first transmission control unit for transmitting, from the first transmitter, a first transmission signal obtained by modulating a first data signal by a subcarrier not overlapping with a subcarrier used for transmission by a transmitter other than the first transmitter at a first timing. When,
At a second timing, a second transmission signal obtained by modulating the first data signal by the subcarrier is transmitted in a state where transmission by the subcarrier used for transmission of the first transmission signal is not performed by a transmitter other than the second transmitter. A second transmission control unit for transmitting from the second transmitter;
A first combined signal obtained by combining a plurality of transmission signals transmitted in parallel from the plurality of transmitters at a first timing and a plurality of transmission signals transmitted in parallel from the plurality of transmitters at a second timing. A combining unit that outputs a second combined signal;
A sampling unit for sampling each of the first synthesized signal and the second synthesized signal;
A transmission signal for each subcarrier included in the first transmission signal is extracted from the sampled first combined signal, and a transmission signal for each subcarrier included in the second transmission signal is extracted from the sampled second combined signal. An extraction unit for extracting
A phase delay for each subcarrier of the second transmission signal with respect to the first transmission signal from a transmission signal for each subcarrier included in the first transmission signal and a transmission signal for each subcarrier included in the second transmission signal A first phase difference calculating unit for calculating
A measurement program that functions as a carrier frequency phase difference calculation unit that calculates a carrier frequency phase difference between the first transmitter and the second transmitter based on the phase delay calculated by the first phase difference calculation unit. .   A recording medium on which the measurement program according to claim 12 is recorded. A measurement program for operating a computer as a measurement device that measures skew between a plurality of transmitters that transmit data signals in parallel using a plurality of subcarriers,
The computer,
A first transmission control unit for transmitting, from the first transmitter, a first transmission signal obtained by modulating a first data signal by a subcarrier not overlapping with a subcarrier used for transmission by a transmitter other than the first transmitter at a first timing. When,
At a second timing, a second transmission signal obtained by modulating the first data signal by the subcarrier is transmitted in a state where transmission by the subcarrier used for transmission of the first transmission signal is not performed by a transmitter other than the second transmitter. A second transmission control unit for transmitting from the second transmitter;
A first combined signal obtained by combining a plurality of transmission signals transmitted in parallel from the plurality of transmitters at a first timing and a plurality of transmission signals transmitted in parallel from the plurality of transmitters at a second timing. A combining unit that outputs a second combined signal;
A sampling unit for sampling each of the first synthesized signal and the second synthesized signal;
A transmission signal for each subcarrier included in the first transmission signal is extracted from the sampled first combined signal, and a transmission signal for each subcarrier included in the second transmission signal is extracted from the sampled second combined signal. An extraction unit for extracting
A phase delay for each subcarrier of the second transmission signal with respect to the first transmission signal from a transmission signal for each subcarrier included in the first transmission signal and a transmission signal for each subcarrier included in the second transmission signal A first phase difference calculating unit for calculating
A measurement program that functions as a skew calculation unit that calculates a skew between the first transmitter and the second transmitter based on the phase delay calculated by the first phase difference calculation unit.   A recording medium on which the measurement program according to claim 14 is recorded.

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