JP7324094B2 - Measuring device and program - Google Patents

Description

The present invention relates to an OFDM (Orthogonal Frequency Division Multiplexing) signal measurement apparatus and program for next-generation terrestrial digital broadcasting.

The next-generation terrestrial broadcasting is scheduled to expand the transmission capacity while inheriting the OFDM modulation system, which is the current ISDB-T (Integrated Services Digital Broadcasting-Terrestrial).

For example, in the current terrestrial digital broadcasting (ISDB-T), 64QAM (Quadrature Amplitude Modulation) with a uniform constellation (uniform constellation; UC) is used as the maximum multilevel modulation as a carrier modulation method. Six bits are transmitted by one carrier symbol (see, for example, Non-Patent Document 1).

On the other hand, in next-generation terrestrial broadcasting, in order to transmit large-capacity content services such as 4K and 8K SHV (Super Hi-Vision) as ultra-high-definition video that surpasses high-definition, multi-level modulation exceeding 64QAM (currently 4096QAM) is required. is considered as the maximum multi-level modulation), and the transmission capacity is expanded using ultra-multi-level OFDM modulation technology including a carrier modulation method of a constellation with non-uniform signal point intervals (non-uniform constellation; NUC) (For example, see Non-Patent Document 2). Furthermore, in the next-generation terrestrial broadcasting, it is being studied to double the transmission capacity by using polarized wave MIMO (multiple-input and multiple-output) technology that simultaneously uses horizontal polarization and vertical polarization.

In the current terrestrial digital broadcasting (ISDB-T), scattered pilots ( SP) signal symbols are arranged, that is, one type of SP signal signal point arrangement (once in 12 carriers in the carrier number direction, once in 4 symbols in the symbol number direction, and 1 symbol of the SP signal is placement).

On the other hand, in the next-generation terrestrial broadcasting, it is possible to change the arrangement of SP signal symbols individually in each layer (A layer, B layer, and C layer) of the data signal (data carrier) multiplexed in the OFDM signal (for example, , once for 6 carriers in the carrier number direction in layer A, once for 12 carriers in the carrier number direction in layer B, and 1 symbol of the SP signal can be specified), It is under consideration to include the information in the TMCC control information and transmit it.

In particular, in next-generation terrestrial broadcasting, use of orthogonal 1-system and 2-system SP signals is being studied when transmitting OFDM signals in the MIMO system.

FIG. 10 shows an example of orthogonal 1-system/2-system SP signal arrangement (hereinafter simply referred to as "SP arrangement") and code as SP signals during MIMO transmission under consideration for next-generation terrestrial broadcasting. It is a figure which shows. For example, during MIMO transmission, the 1-system SP arrangement is transmitted with horizontal polarization, and the 2-system SP arrangement is transmitted with vertical polarization. These 1-system and 2-system SP signals are generated corresponding to the sign inversion method for each layer. In the sign inversion method, the SP signal of the 2nd system is obtained by multiplying the SP signal arranged as the 1st system by +1 or -1 (the absolute value of the amplitude of the SP is maintained).

More specifically, the SP arrangement of system 2 is the first SP symbol in the frame of the OFDM signal of system 2 (hereinafter also referred to as "OFDM frame") (the first SP in the time direction of the carrier number at the beginning of system 2). symbol), the SP symbol at the beginning of the OFDM frame of system 1 (the first SP symbol in the time direction of the first carrier number of system 1) is multiplied by +1 (non-sign inversion), and the SP symbol at the beginning of this OFDM frame , the code values of the SP symbols are alternately inverted in the symbol direction (time direction) and carrier direction (frequency direction) in the carrier-symbol space defined based on the carrier interval Dx and the symbol interval Dy. Furthermore, in the SP arrangement of the 2 system, the basic block of the carrier-symbol space including the SP symbol at the beginning of the OFDM frame is arranged by alternately inverting the code of the SP symbol in basic block units in the carrier direction and the symbol direction. and In this way, the SP arrangement of system 2 is based on the SP symbol at the beginning of the OFDM frame, and the SP arrangement of system 1 is based on SP (non-sign inverted) symbols and SP (sign inverted) in the symbol direction (time direction). ) symbols are alternately assigned, and the signs of the SP symbols are alternately inverted in the carrier direction and the symbol direction in units of basic blocks in the carrier-symbol space.

By the way, an OFDM signal measuring device compatible with polarization MIMO is commercially available (see, for example, Non-Patent Document 3). A conventional OFDM signal measuring device performs demodulation of a MIMO-OFDM signal sequentially from the first symbol of an OFDM frame. Separation of the 1st system and the 2nd system is performed using the SP symbol whose sign is inverted in the processing of the equalization unit. SP symbols are also used for channel estimation. Therefore, in the conventional MIMO-OFDM signal measurement device, the reception power, frequency characteristics, constellation, MER (Modulation Error Ratio), and delay profile are calculated based on the detection of the first symbol of the OFDM frame. It is measurable.

“Transmission method standard for terrestrial digital television broadcasting ARIB STD-B31 Version 2.2”, revised on March 18, 2014, Association of Radio Industries and Businesses (ARIB) Takuya Tsuji, Shingo Asakura, Susumu Saito, Tomohiro Saito, Kazuhiko Shibuya, “Transmission Technology for Next-Generation Terrestrial Broadcasting -Improvement of Ultra-Multilevel Signal Transmission Characteristics by Non-Uniform Mapping-”, Institute of Image Information and Television Engineers Technical Report, Vol. 38, No. 5, January 2014, pp.117-120 “MIMO Performance and Condition Numbers in LTE Tests”, Keysight Technologies, [online], [searched on August 19, 2019], Internet <URL: http://literature.cdn.keysight.com/litweb/ pdf/5990-4759EN.pdf>

A conventional OFDM signal measuring apparatus as disclosed in Non-Patent Document 3 detects the beginning of an OFDM frame during demodulation processing of a MIMO-OFDM signal. Detecting the beginning of an OFDM frame requires a buffer memory in the measuring device to temporarily store at least one OFDM frame of the input signal. An OFDM frame has a length of 224 symbol periods for an FFT size of 8k, 112 symbol periods for 16k, and 56 symbol periods for 32k. At least 224 symbol periods are required as memory buffer capacity. For this reason, the conventional OFDM signal measuring apparatus needs to prepare a buffer memory having a buffer capacity for at least one OFDM frame, which poses a problem in terms of cost reduction. In addition, conventional MIMO-OFDM signal measurement equipment requires the necessary programs and hardware to detect the beginning of OFDM frames, just like a normal receiver, and there is room for improvement in terms of cost. there were. Furthermore, since the conventional OFDM signal measuring apparatus requires time to acquire signals for at least one OFDM frame, there is room for improvement in the time required to obtain signal analysis results.

In addition, in the conventional OFDM signal measurement device, correct measurement of frequency characteristics and constellation is necessary to enable signal analysis even when the code relationship of SP arrangement differs for each layer, unless the beginning of the OFDM frame is detected. is not possible.

FIG. 11 is a diagram showing an example of SP arrangement for each layer during MIMO transmission in next-generation terrestrial broadcasting. At the time of MIMO transmission in next-generation terrestrial broadcasting, the same SP arrangement can be used for each layer (the code relationship between layers is also the same), and the SP arrangement can be different for each layer (when the code relationship between layers is also different). ), and can be configured with various SP arrangement patterns. When the SP arrangement is the same for each layer, the code at the beginning of the SP is aligned for each symbol (in the example shown in the left diagram of FIG. 11, Dy= 4, and the sign relation between layers is the same). On the other hand, when the SP arrangement is different for each layer, depending on the symbol, there are cases where the SP arrangement and code relationship are different for each layer (in the example shown in the right diagram of FIG. 10, layers A, B, and C Each layer has a combination of values of Dy=1, 2, or 4, and the code relationship between layers may also differ).

However, in the conventional OFDM signal measuring device, unless the beginning of the OFDM frame is detected, it is impossible to demodulate so that the different SP arrangements and code relationships for each layer are linearly continuous as frequency characteristics. The frequency characteristic cannot be linearly continued except for the detection of the head, and the constellation cannot be measured correctly.

Therefore, in view of the above-mentioned problems, an object of the present invention is to provide a measuring apparatus and a program capable of measuring MIMO-OFDM signals at a lower cost and in a shorter time even if the SP arrangement differs for each layer. to provide.

The measuring apparatus of the present invention is an OFDM signal measuring apparatus that receives a MIMO-transmitted OFDM signal and uses a frequency based on a scattered pilot (SP) signal for each layer in the OFDM signal after synchronous regeneration. and a signal analysis means for analyzing and measuring a measurement value including at least a constellation of data signals in the OFDM signal, wherein the signal analysis means analyzes the SP signal for each layer in the OFDM signal after synchronous reproduction. and equalization means for executing equalization processing for correcting the OFDM signal based on the signal point arrangement of the SP signal of system 1 and the signal point arrangement of the SP signal of system 1. During MIMO transmission having two types of SP arrangement patterns, which are signal point arrangements of two-system SP signals in which predetermined SP symbols are regularly sign-inverted, the first symbol of the SP signal for each layer is obtained from the OFDM signal after synchronous regeneration. a buffer memory for storing an OFDM signal for a predetermined symbol period from the head symbol of the SP signal; and a predetermined propagation path estimation by performing complex division on the OFDM signal for the predetermined symbol period. SP complex division means for estimating the amplitude/phase change amount of the SP signal by, SP time direction interpolation means for executing SP interpolation processing in the time direction using the amplitude/phase change amount, and the SP interpolation processing in the time direction frequency characteristic conversion means for converting the subsequent OFDM signal into an OFDM signal having a frequency characteristic in which the SP signal is linearly continuous when the SP signal has nonlinear frequency characteristics; and OFDM obtained from the frequency characteristic conversion means. SP frequency direction interpolation means for performing SP interpolation processing in the frequency direction on a signal, and complex division means for correcting the OFDM signal by performing complex division on the OFDM signal after the SP interpolation processing in the frequency direction. characterized by

Further, in the measuring apparatus of the present invention, the frequency characteristic conversion means determines whether the code of the leading symbol of the SP signal is the same or different on the same symbol for each layer of the OFDM signal after the SP interpolation processing in the time direction. is determined, and when the SP signal has a nonlinear frequency characteristic, the SP signal is converted into an OFDM signal having a linearly continuous frequency characteristic.

Further, in the measuring apparatus of the present invention, the frequency characteristic conversion means sets the frequency characteristic of the SP signal in the OFDM signal after the SP interpolation processing in the time direction as the first frequency characteristic, and the SP signal having the first frequency characteristic. The presence or absence of a layer in which the sign of the signal may be inverted and the periodicity of the sign inversion are determined from the TMCC information, and for the SP signal of the layer determined as having the possibility of sign inversion, for the predetermined symbol period, The SP symbol whose sign is inverted according to the determined periodicity is converted into a second frequency characteristic in which the sign is inverted into a non-sign-inverted SP symbol, and the first and second frequency characteristics are compared to obtain a linear is selected and output to the SP frequency direction interpolating means.

Further, in the measuring apparatus of the present invention, the frequency characteristic conversion means calculates a sum of amplitude distances between adjacent SP symbols in the carrier direction for each of the first and second frequency characteristics, Of the second frequency characteristics, one having a smaller sum of amplitude distances is determined to be linearly continuous frequency characteristics, and an OFDM signal having more linearly continuous frequency characteristics is selected and output. .

Furthermore, the program of the present invention constitutes a program for causing a computer to function as the signal analysis means in the measuring apparatus of the present invention.

According to the present invention, it is possible to measure a MIMO-OFDM signal at a lower cost and in a shorter time even if the SP arrangement differs for each layer. In other words, according to the present invention, detection of the beginning of an OFDM frame becomes unnecessary, so that the necessary programs and hardware become unnecessary, and the buffer capacity of the buffer memory for signal analysis of the MIMO-OFDM signal can be reduced. It is possible to shorten the analysis time.

1 is a block diagram showing a schematic configuration of an OFDM signal measuring apparatus according to an embodiment of the present invention; FIG. 1 is a block diagram showing a schematic configuration of a signal analysis section in an OFDM signal measuring apparatus according to an embodiment of the present invention; FIG. 1 is a block diagram showing a schematic configuration of an equalization section of an example in an OFDM signal measuring apparatus of an embodiment according to the present invention; FIG. FIG. 4 is a block diagram showing a schematic configuration of an equalization section of a comparative example in a conventional OFDM signal measuring device; FIG. 10 is a diagram schematically showing the actual operation of the equalizer of the comparative example in the OFDM signal measuring device of the prior art, the operation when detecting the beginning of the OFDM frame, the frequency characteristics obtained at this time, and the constellation; be. FIG. 10 is a diagram schematically showing the operation when trying to detect the beginning of an SP, the frequency characteristics obtained at this time, and the constellation as a problem of the equalization unit of the comparative example in the OFDM signal measuring device of the prior art; . 4 is a flow chart showing control of a frequency characteristic conversion section during MIMO transmission provided in an equalization section of an embodiment of an OFDM signal measuring apparatus according to an embodiment of the present invention; 4(a) to 4(d) are diagrams for explaining control of a frequency characteristic conversion section provided in an equalization section of an example of an OFDM signal measuring apparatus according to an embodiment of the present invention. FIG. As the actual operation of the equalization unit of the embodiment of the OFDM signal measuring apparatus according to the present invention, the operation of detecting the beginning of the SP, the frequency characteristics obtained at this time, and the constellation are schematically shown. is a diagram shown in FIG. FIG. 2 is a diagram showing an example of arrangement and codes of orthogonal 1-system and 2-system pilot signals as scatter pilots (SP) during MIMO transmission under consideration for next-generation terrestrial broadcasting. FIG. 10 is a diagram showing an example of SP arrangement for each layer during MIMO transmission in next-generation terrestrial broadcasting;

An OFDM signal measuring apparatus 1 according to an embodiment of the present invention will be described below with reference to the drawings.

(overall structure)
FIG. 1 is a block diagram showing a schematic configuration of an OFDM signal measuring apparatus 1 according to an embodiment of the present invention. The measurement device 1 shown in FIG. Received OFDM signals are distinguished from OFDM signals transmitted by the SISO system using one of the polarized waves, and are configured as a device for performing predetermined measurements of these OFDM signals. It includes converters 13 and 14 , analog/digital (A/D) converters 15 and 16 , a signal analyzer 17 , and a data collector 18 . The data collection unit 18 has a display unit 181 , an operation unit 182 and a recording unit 183 .

It should be noted that the MIMO method and the MISO method do not need to be distinguished from each other in the measurement apparatus 1 from the viewpoint of measuring OFDM signals for each of a plurality of types of polarization (horizontal polarization and vertical polarization in this example). MISO is included when MIMO is used in the following description. Furthermore, since the measuring apparatus 1 is configured to measure MIMO OFDM signals, it can also measure SISO OFDM signals. Therefore, in the following description, an example will be described in which the measuring apparatus 1 mainly receives OFDM signals transmitted by the MIMO method and performs predetermined measurements, which will be described later.

The received power measuring unit 11 receives a horizontally polarized OFDM signal via a horizontally polarized receiving antenna (not shown), measures the received power, generates received power data indicating the measurement result, and performs signal analysis. Output to unit 17 . In addition, the received power measuring unit 12 receives a vertically polarized OFDM signal via a vertically polarized wave receiving antenna (not shown), measures the received power, and generates received power data indicating the measurement result. Output to the signal analysis unit 17 . Therefore, the reception power measurement units 11 and 12 are configured as reception power measurement means for receiving the OFDM signal for each polarization, measuring the reception power for each polarization, and generating reception power data for each polarization.

The frequency converter 13 frequency-converts a horizontal polarized OFDM signal received via a horizontal polarized wave reception antenna (not shown) into an intermediate frequency signal, and outputs the intermediate frequency signal to the A/D converter 15 . Further, the frequency converter 14 frequency-converts a vertically polarized OFDM signal received via a vertically polarized wave reception antenna (not shown) into an intermediate frequency signal, and outputs the intermediate frequency signal to the A/D converter 16 . Accordingly, the frequency conversion units 13 and 14 are configured as frequency conversion means for frequency-converting the OFDM signals received for each polarization into signals of intermediate frequencies.

The A/D conversion unit 15 converts the horizontally polarized OFDM signal frequency-converted to the intermediate frequency into a digital value, and outputs the digital value to the signal analysis unit 17 . Further, the A/D converter 16 converts the vertically polarized OFDM signal frequency-converted to the intermediate frequency into a digital value, and outputs the digital value to the signal analysis unit 17 . Accordingly, the A/D conversion units 15 and 16 are configured as analog/digital conversion means for converting the OFDM signal for each polarization frequency-converted to the intermediate frequency into a digital value.

The signal analysis unit 17 includes means for demodulating the TMCC signal and the data signal assigned to each layer, which are multiplexed on the OFDM signal for each polarization converted into the digital value, and estimating the phase and amplitude value of the data signal. Means for analyzing and measuring the delay profile based on the possible pilot signal (SP signal), frequency characteristics, the constellation of the data signal, and the modulation error ratio (MER), and TMCC (Transmission and Multiplexing Configuration Control Information) Analysis of means for analyzing and measuring the MER of a signal and condition numbers indicating evaluation values related to transmission of the multiple types of polarization (horizontal polarization and vertical polarization in this example) and means for outputting each measured value including the received power data for each polarization obtained from the received power measuring units 11 and 12 to the display unit 181 or the recording unit 183 .

Although not essential, the signal analysis unit 17 in this embodiment further includes means for demodulating the LLch signal multiplexed with the OFDM signal for each polarization and analyzing and measuring the MER of the LLch signal.

Then, the signal analysis unit 17 can selectively specify from the operation unit 182 which of the data signal, TMCC signal, and LLch signal the MER of which signal is to be measured.

In addition, the signal analysis unit 17 can measure all of the measured values of the delay profile and frequency characteristics based on the SP signal, the constellation and MER of the data signal for each layer, and the condition number. However, as a modified example, it is also possible to configure the operation unit 182 to selectively specify a part of each measurement value to be measured.

Each measurement value measured by the signal analysis unit 17 can be specified to be displayed on the display unit 181 or recorded on the recording unit 183 by setting from the operation unit 182 .

The data collection unit 18 has a function of automatically receiving information (GPS information) on the reception point, operates the signal analysis unit 17 in response to an analysis instruction from the operation unit 182, and collects each measurement value measured by the signal analysis unit 17. , and the information of the reception point (GPS information) are displayed on the display unit 181 in one screen, or recorded in the recording unit 183 .

(Signal analysis part)
FIG. 2 is a block diagram showing a schematic configuration of the signal analysis section 17 in the OFDM signal measuring apparatus 1 according to one embodiment of the present invention.

The signal analysis unit 17 includes a horizontal polarization signal analysis unit 17H, a vertical polarization signal analysis unit 17V, and a condition number calculation unit 17C, which operate based on instructions from the operation unit 182 .

The horizontal polarization signal analysis unit 17H receives the horizontal polarization OFDM signal converted into the digital value obtained from the A/D conversion unit 15, and converts the OFDM signal based on the instruction from the operation unit 182. demodulates the TMCC signal and LLch signal multiplexed into each layer and the data signal assigned to each layer, selectively performs predetermined measurements related to the data signal, the TMCC signal, the LLch signal, and the SP signal, and measures the received power Each measured value including the reception power data of the horizontally polarized OFDM signal obtained from the unit 11 is output to the display unit 181 or the recording unit 183 .

The vertical polarization signal analysis unit 17V receives the vertical polarization OFDM signal converted into the digital value obtained from the A/D conversion unit 16, and converts the OFDM signal based on the instruction from the operation unit 182. demodulates the TMCC signal and LLch signal multiplexed into each layer and the data signal assigned to each layer, selectively performs predetermined measurements related to the data signal, the TMCC signal, the LLch signal, and the SP signal, and measures the received power Each measured value including the reception power data of the OFDM signal for vertical polarization obtained from the unit 12 is output to the display unit 181 or the recording unit 183 .

The condition number calculation unit 17C calculates the maximum singularity based on the measurement results (delay profile and frequency response) of the horizontal polarization signal analysis unit 17H and the vertical polarization signal analysis unit 17V from the matrix of the channel response constituting MIMO. A value and a minimum singular value are obtained, a condition number is calculated from their ratio, and the calculated value is output to the display unit 181 or the recording unit 183 . Calculation of this condition number is performed when measurement results of the delay profile and frequency response are obtained by the horizontal polarization signal analysis unit 17H and the vertical polarization signal analysis unit 17V based on an instruction from the operation unit 182. . If the value of the condition number is small, it indicates that the propagation path constituting MIMO is in good condition, and if the value is large, it indicates that it is in bad condition.

In FIG. 2, since the vertical polarization signal analysis unit 17V is configured in the same manner as the horizontal polarization signal analysis unit 17H, only the components of the horizontal polarization signal analysis unit 17H are illustrated in detail. . Hereinafter, the components of the horizontal polarization signal analysis unit 17H will be described as a representative.

The horizontal polarization signal analysis unit 17H includes a data input/output unit 170, a synchronization reproduction unit 171, a TMCC decoding unit 172, a control information reading unit 173, an equalization unit 175, a signal separation unit 176, and a deinterleaving unit. A section 177, a layer separation section 178, and MER calculation sections 179A, 179B, and 179C.

The data input/output unit 170 inputs the reception power data of the horizontally polarized OFDM signal obtained from the reception power measurement unit 11, and operates the operation unit 182 to synchronize with other measured values such as the delay profile and frequency response. It outputs to the display unit 181 or the recording unit 183 based on the instruction from.

The synchronization reproduction unit 171 receives the OFDM signal for horizontal polarization that has been converted into the digital value obtained from the A/D conversion unit 15, performs orthogonal demodulation, and performs symbol synchronization and carrier frequency synchronization reproduction of the OFDM signal. , which includes a guard interval (GI) correlator 1711 , an LLch, TMCC correlator 1712 , and an LLch, TMCC designator 1713 .

A guard interval (GI) correlator 1711 detects an effective symbol position by correlating guard intervals by comparing signals at times separated by an FFT (Fast Fourier Transform) window for the orthogonally demodulated OFDM signal, This is a functional unit that synchronizes carrier frequencies.

LLch, TMCC correlation section 1712 uses the LLch signal and TMCC signal multiplexed in the OFDM signal in order to detect the carrier frequency shift in the OFDM signal after the guard interval correlation, or the LLch, TMCC designation section 1713, using the LLch signal and the TMCC signal designated by the external input, performs correlation detection of the carrier position of the OFDM signal. LLch signals and TMCC signals are signals with carrier numbers determined in advance, and usually have larger amplitudes than data signals (data carriers). , and the symbol synchronization and carrier frequency of the OFDM signal can be synchronously reproduced with high accuracy.

The LLch, TMCC designation unit 1713 is a functional unit that designates the LLch signal and the TMCC signal by external input from the operation unit 182 to the LLch, TMCC correlation unit 1712. The TMCC control information received can be arbitrarily set from the operation unit 182 .

The TMCC decoding unit 172 extracts and decodes the TMCC signal from the OFDM signal that has undergone symbol synchronization and carrier frequency synchronous reproduction through the LLch and TMCC correlation unit 1712, thereby acquiring TMCC control information and reading the control information. Output to unit 173 . Transmission parameter information indicating the encoding modulation scheme such as the carrier modulation scheme and the error correction coding rate can be obtained by decoding the TMCC signal.

Control information reading section 173 outputs the TMCC control information obtained from TMCC decoding section 172 to MER calculating sections 179A, 179B, and 179C for each layer. When the TMCC control information designates the TMCC signal by the external input from the operation unit 182 via the LLch and TMCC designation unit 1713, the designated TMCC control information is eventually read out, but the external input from the operation unit 182 TMCC control information may be read directly. That is, the operation unit 182 uses the MER calculation units 179A, 179B, and 179C to read control information to determine which of the externally input TMCC control information and the TMCC control information in the TMCC signal multiplexed on the OFDM signal is to be used. 173 can be set.

As with the LLch signal and the TMCC signal, the SP signal has a predetermined carrier number, amplitude and phase, and is known to the measuring device 1 side. In the next-generation terrestrial broadcasting, it is possible to change the symbol arrangement of the SP signal individually for each layer (A layer, B layer, and C layer) of the data carrier multiplexed in the OFDM signal. In the measurement apparatus 1 according to the embodiment, the SP signal to be extracted can be designated to the equalization section 175 by an external input from the operation section 182 .

The equalization unit 175 has a unique function according to the present invention, which will be described in detail later with reference to FIG. Detect the leading symbol of the SP signal (SP symbol at the beginning of the carrier number), and the OFDM signal for a predetermined symbol period (20 symbol periods in this example, a symbol period shorter than 1 OFDM frame) from the leading symbol of the SP signal has a buffer memory 1752 for storing Note that the buffer memory 1752 according to the present invention does not need to store OFDM signals for one OFDM frame period (at least 224 symbol periods) as in the prior art.

Then, the equalization unit 175 performs complex division on the OFDM signal stored in the buffer memory 1752 to perform a predetermined propagation path estimation (SP signal as a known transmission signal and SP signal as an actual reception signal. After estimating the amount of change in amplitude and phase by estimation using a channel matrix) and executing SP interpolation processing in the time direction, the frequency characteristic conversion unit 1755 according to the present invention performs when the SP signal has a nonlinear frequency characteristic, Processing is performed to convert the SP signal into an OFDM signal having linearly continuous frequency characteristics.

Subsequently, the equalization unit 175 executes equalization processing for correcting the OFDM signal by performing SP interpolation processing in the frequency direction on the OFDM signal obtained from the frequency characteristic conversion unit 1755 and performing complex division. Output to the signal separation unit 176 .

In addition, based on the instruction from the operation unit 182, the equalization unit 175, for the SP signal in the OFDM signal after the SP interpolation processing, the transmission device (known on the measurement device 1 side) that transmitted the corresponding OFDM signal From the transmission antenna (not shown) to the reception antenna (not shown) of the measuring device 1 of the present embodiment, each path from the propagation path response (variation on the frequency axis between transmission and reception) for each polarization By transforming the frequency domain signal into a time domain signal by inverse fast Fourier transforming the channel response of , a delay profile indicating the amount of change on the time axis between transmission and reception is obtained. Frequency characteristics are obtained by Fourier transform, and these measured values are output to the display section 181 or the recording section 183 . In other words, the delay profile is measured on the time axis, and the frequency characteristic is measured on the frequency axis.

The signal separation unit 176 separates the OFDM signal after SP interpolation and complex division processing by the equalization unit 175 by a signal separation/extraction method by one of ZF, MMSE, and MLD designated by the operation unit 182. , the vertical polarization component is separated and removed from the horizontal polarization OFDM signal of the MIMO scheme, and output to the deinterleaving section 177 .

Since the configuration of the horizontal polarization signal analysis unit 17H is described here, the signal separation unit 176 provided in the horizontal polarization signal analysis unit 17H converts the MIMO horizontal polarization OFDM signal into the vertical polarization. A signal separation unit 176, which is also provided in the vertical polarization signal analysis unit 17V, separates and removes the horizontal polarization component from the MIMO vertical polarization OFDM signal. Configured. Therefore, the signal separation units 176 provided in the horizontal polarization signal analysis unit 17H and the vertical polarization signal analysis unit 17V may be integrated so as to separate signals for each polarization. In any case, the processing after the deinterleaving unit 177 shown in FIG. 2 is performed on the OFDM signal after the SP interpolation processing for each polarization.

The deinterleaving unit 177 performs deinterleaving processing on the OFDM signal for horizontal polarization obtained through the signal separation unit 176 to restore the signal interleaved by the transmission device (not shown) side, and the layer separation unit 178 performs deinterleaving processing. output to

The layer separation unit 178 separates the data signals (data carriers) of each layer (A layer, B layer, and C layer) multiplexed on the OFDM signal for horizontal polarization, and generates MER calculation units 179A, 179B, 179C.

In addition, based on an instruction from the operation unit 182, the layer separation unit 178 displays the constellation of the data signals (data carriers) of each layer (A layer, B layer, and C layer) for each polarized wave on the display unit 181. Or output to the recording unit 183 .

In addition, the layer separation section 178 multiplexes and outputs the TMCC signal and the LLch signal in the IQ signal format separately from the corresponding data signal to one or more of the MER calculation sections 179A, 179B, and 179C. Note that the layer separation unit 178 of this example multiplexes the TMCC signal and the LLch signal for all of the MER calculation units 179A, 179B, and 179C so that the TMCC signal or the LLch signal can be selected and specified from any layer. ing.

The MER calculation units 179A, 179B, and 179C selectively calculate the MER of the data signal, the TMCC signal, or the LLch signal of the corresponding coded modulation scheme based on the TMCC control information, based on the instruction from the operation unit 182. and output to the display unit 181 or the recording unit 183.

(Structure of Equalization Section of One Example According to the Present Invention)
FIG. 3 is a block diagram showing a schematic configuration of the equalization section 175 of one example in the OFDM signal measuring apparatus 1 of one embodiment according to the present invention. The equalization unit 175 of this embodiment includes an SP head detection unit 1751, a buffer memory 1752, an SP complex division unit 1753, an SP time direction interpolation unit 1754, a frequency characteristic conversion unit 1755, an SP frequency direction interpolation unit 1756, and a complex division unit 1757. , and a data output unit 1758 .

The equalization unit 175 of this embodiment shown in FIG. 3 has a buffer memory 1752 with a smaller buffer capacity than the equalization unit 175P based on the prior art (described later with reference to FIG. 4). , the provision of an SP head detector 1751 for detecting the head symbol of the SP signal (the SP symbol at the head of the carrier number) instead of detecting the head of the OFDM frame, and the newly provided frequency characteristic converter 1755. , are different.

The SP head detection unit 1751 receives the OFDM signal after synchronous reproduction from the synchronous reproduction unit 171, detects the head symbol of the SP signal, and detects a predetermined symbol period (20 symbol periods in this example) from the head symbol of the SP signal. The OFDM signal for a symbol period shorter than one OFDM frame is stored in the buffer memory 1752 .

In particular, as described with reference to FIG. 10, the SP head detector 1751 regularly detects predetermined SP symbols for the signal point arrangement of the SP signal of system 1 and the signal point arrangement of the SP signal of system 1. Even in MIMO transmission with two types of SP arrangement patterns, which are signal point arrangements of two systems of SP signals whose signs are inverted, the leading symbol of the SP signal for each layer is detected from the OFDM signal after synchronous regeneration, and the SP The OFDM signal for a predetermined symbol period (20 symbol periods in this example) from the leading symbol of the signal is stored in the buffer memory 1752 .

Therefore, the buffer memory 1752 stores the OFDM signal for a predetermined symbol period (20 symbol periods in this example) from the leading symbol of the SP signal. Here, in next-generation terrestrial broadcasting, as described with reference to FIG. and can be configured with various SP placement patterns for the data symbols. On the other hand, since the equalization unit 175 of this embodiment is provided with an SP head detection unit 1751 and a frequency characteristic conversion unit 1755, which will be described later, the buffer memory 1752 can store up to 20 symbols in any SP arrangement pattern. The buffer capacity for the period is sufficient. That is, as illustrated in FIG. 11, each of the A layer, the B layer, and the C layer has a combination of values of Dy=1, 2, or 4, and the buffer memory 1752 has a maximum of 4 symbols in the time direction. (Dy=4)×5 symbols (maximum interval)=20 symbol periods of OFDM signals may be temporarily stored. Note that the buffer memory 1752 can have a buffer capacity of less than 20 symbol periods when only SP arrangements with a specific Dy value are specified and measured. can be a buffer capacity for temporarily storing OFDM signals for 1 symbol (Dy=1)×1 symbol (minimum interval)=1 symbol period.

The SP complex division unit 1753 performs complex division on the OFDM signal for a predetermined symbol period from the first symbol of the SP signal stored in the buffer memory 1752, thereby estimating the propagation path, and presuming the SP signal as a known transmission signal. Then, the amplitude/phase change amount of the SP signal as the actual received signal is detected, and the OFDM signal for the symbol period and information on the amplitude/phase change amount used for SP interpolation are sent to the SP time direction interpolation unit Output to 1754.

The SP time direction interpolation unit 1754 executes SP interpolation processing in the symbol direction (time direction) of the OFDM signal for the symbol period based on the information on the amplitude/phase change amount obtained from the SP complex division unit 1753, The OFDM signal after the SP interpolation processing in the time direction is output to the frequency characteristic conversion section 1755 .

The frequency characteristic conversion unit 1755 will be described later in detail with reference to FIGS. 7 and 8. For each OFDM signal after SP interpolation processing in the time direction, the OFDM signal after SP interpolation processing in the time direction is converted to It is determined whether the codes of the leading symbols of the SP signals on the same symbol are the same or different, and when the SP signal has nonlinear frequency characteristics, the SP signal is converted into an OFDM signal having linearly continuous frequency characteristics. Output to SP frequency direction interpolation section 1756 . The frequency characteristics are two-dimensional, with the horizontal axis representing the carrier numbers of the SP signals represented for all of the A, B, and C layers, and the vertical axis representing the amplitude of the SP signals for each layer. be able to. Also, during non-MIMO transmission, the processing of this frequency characteristic conversion unit 1755 can be omitted and bypassed.

SP frequency direction interpolation section 1756 performs SP interpolation processing in the frequency direction on the OFDM signal having frequency characteristics obtained from frequency characteristic conversion section 1755 and outputs the result to complex division section 1757 .

The complex division unit 1757 performs equalization processing for correcting the OFDM signal by performing complex division on the original OFDM signal using the OFDM signal after the SP interpolation processing in the frequency direction by the SP frequency direction interpolation unit 1756, Output to the signal separation unit 176 .

Based on an instruction from the operation unit 182, the data output unit 1758 externally outputs the frequency characteristic of the SP signal in the OFDM signal after the SP interpolation processing in the frequency direction by the SP frequency direction interpolation unit 1756 and the corresponding delay profile data. do. Based on an instruction from the operation unit 182, the data output unit 1758 outputs the frequency characteristics (first and second frequency characteristics) of the SP signal obtained from the SP time direction interpolation unit 1754 and the frequency characteristics conversion unit 1755, respectively. , the corresponding delay profile data can also be configured to be externally output.

(Configuration of equalization unit of comparative example based on conventional technology)
Here, with reference to FIGS. 4 to 6, the equalization unit 175P of a comparative example in the conventional measuring device disclosed in Non-Patent Document 3 and its problems will be described. FIG. 4 is a block diagram showing a schematic configuration of an equalization section 175P of a comparative example in a conventional OFDM signal measuring apparatus. Also, FIG. 5 shows, as the actual operation of the equalizer 175P of the comparative example in the conventional OFDM signal measuring apparatus, the operation when detecting the beginning of the OFDM frame, the frequency characteristics obtained at this time, and the constellation. is a diagram schematically showing the . FIG. 6 shows the operation when trying to detect the beginning of the SP, the frequency characteristics obtained at this time, and the constellation as a problem of the equalization unit 175P of the comparative example in the OFDM signal measuring apparatus of the prior art. FIG. 3 is a schematic diagram;

First, as shown in FIG. 4, the equalization unit 175P of the comparative example based on the conventional technology includes an OFDM frame head detection unit 1751P, a buffer memory 1752P, an SP complex division unit 1753, an SP time direction interpolation unit 1754, an SP frequency direction interpolation unit A section 1756 , a complex division section 1757 and a data output section 1758 are provided. The operations of the SP complex division unit 1753, the SP time direction interpolation unit 1754, the SP frequency direction interpolation unit 1756, the complex division unit 1757, and the data output unit 1758 in the equalization unit 175P are the same as those according to the present invention shown in FIG. It operates in the same manner as the equalization unit 175 of the embodiment. Therefore, in FIG. 4, the same reference numerals are assigned to the same components as the equalization unit 175 of the embodiment according to the present invention shown in FIG.

In the equalization section 175P of the comparative example shown in FIG. 4, an OFDM frame head detection section 1751P is provided instead of the SP head detection section 1751 shown in FIG. 3, and the frequency characteristic conversion section 1755 shown in FIG. 3 is not provided.

The OFDM frame head detector 1751P detects the head symbol of the OFDM frame from the input OFDM signal and stores the OFDM signal for one OFDM frame period in the buffer memory 1752P.

Therefore, the buffer memory 1752P stores OFDM signals for one OFDM frame period (at least 224 symbol periods). Therefore, in the equalization unit 175P of the comparative example, the OFDM signal for one OFDM frame period (at least 224 symbol periods) is stored as the buffer capacity of the buffer memory 1752P for detecting the beginning of the OFDM frame with an arbitrary FFT size. buffer capacity is required, which results in high cost.

The SP complex division unit 1753 shown in FIG. 4 estimates the propagation path by performing complex division on the OFDM signal for one OFDM frame period (at least 224 symbol periods) stored in the buffer memory 1752P, and estimates a transmission signal that is known in advance. and the amplitude and phase variation of the SP signal as the actual received signal are detected, and the OFDM signal for the symbol period and information on the amplitude and phase variation used for SP interpolation are SP Output to the time direction interpolation unit 1754 .

The SP time direction interpolation unit 1754 shown in FIG. 4 performs SP interpolation processing in the symbol direction (time direction) of the OFDM signal for the symbol period based on the information on the amplitude/phase change amount obtained from the SP complex division unit 1753. Then, the OFDM signal after SP interpolation processing in the time direction is output to the SP frequency direction interpolation section 1756 .

The SP frequency direction interpolation section 1756 shown in FIG. 4 performs SP interpolation processing in the frequency direction on the OFDM signal after the SP interpolation processing in the time direction, and outputs the result to the complex division section 1757 .

The complex division unit 1757 shown in FIG. 4 uses the OFDM signal after SP interpolation processing in the frequency direction by the SP frequency direction interpolation unit 1756 to perform complex division on the original OFDM signal, thereby performing equalization processing for correcting the OFDM signal. and output to the signal separator 176 .

The data output unit 1758 shown in FIG. 4 externally outputs the frequency characteristic of the SP signal in the OFDM signal after the SP interpolation processing in the frequency direction by the SP frequency direction interpolation unit 1756 and the corresponding delay profile data.

Here, an OFDM signal for one OFDM frame period includes SP (non-sign inversion) and SP (sign inversion) having periodicity. For this reason, for example, when the SP arrangement is the same for each layer (the code relation between layers is also the same) as shown in the upper left diagram of FIG. When the SP arrangement is different for each layer (the code relation between layers may also be different) as shown in (in the example shown, Dy=2 in layers A and B, and Dy=4 in layer C), However, since the equalization unit 175P performs equalization processing based on the beginning of the OFDM frame in the frequency direction as well, all frequency characteristics of each layer (A layer, B layer, C layer) are linearly continuous. can be obtained (see the middle left and middle right diagrams of FIG. 5). The left middle diagram and the right middle diagram of FIG. 5 show the frequency characteristics of all the layers A, B, and C combined. ”), an imaginary part of horizontal polarization (“horizontal Im”), a real part of vertical polarization (“vertical Re”), and an imaginary part of vertical polarization (“vertical Im”).

Then, since a linearly continuous frequency characteristic can be obtained, as a result, as illustrated in the lower left and lower right diagrams of FIG. 5, the signal constellation equalized using this frequency characteristic is correctly obtained. In the lower left diagram and the lower right diagram of FIG. 5 , the constellation at the time of vertical polarization of the C layer is illustrated with the horizontal axis and the vertical axis as the I axis and the Q axis, respectively. The coordinate values of the real part of the vertical polarization (“vertical Re”) and the imaginary part of the vertical polarization (“vertical Im”) are normalized. Therefore, when analyzing the OFDM signal for one OFDM frame period, the equalization unit 175P of the comparative example shown in FIG. , B layer, and C layer constellations can be stably measured.

However, in the equalization unit 175P of the comparative example shown in FIG. 4, it is necessary to prepare a buffer memory 1752P having a buffer capacity for at least one OFDM frame, which is disadvantageous for cost reduction. In addition, the OFDM frame head detection unit 1751P requires programs and hardware necessary for detecting the head of the OFDM frame, which is also disadvantageous for cost reduction. Furthermore, the equalization unit 175P of the comparative example requires time to acquire signals for at least one OFDM frame, which is also disadvantageous in shortening the signal analysis time.

By the way, even if a relatively large buffer capacity of at least one OFDM frame is allowed in the buffer memory 1752P in the equalization unit 175P of the comparative example shown in FIG. Simply replacing it with the SP head detection unit 1751 shown in FIG. 3 cannot linearly continue the SP arrangement and code relationship, which differ for each layer, as frequency characteristics. This will be described with reference to FIG.

As shown in FIG. 6, the equalization unit 175P when the OFDM frame head detection unit 1751P shown in FIG. 4 is simply replaced with the SP head detection unit 1751 shown in FIG. As shown, when the SP arrangement is the same for each layer (the code relationship between layers is also the same) (in the example shown, Dy=4 for all layers), the frequency direction is based on the leading symbol of the SP signal. Therefore, the periodicity of SP (non-sign inversion) and SP (sign inversion) is maintained, and all frequency characteristics of each layer (A layer, B layer, C layer) are linearly continuous. can be obtained (see the middle left diagram in FIG. 6), and measurements of the constellations of the A layer, B layer, and C layer can also be stably obtained (see the lower left diagram in FIG. 6).

However, as shown in the upper right diagram of FIG. 6, when the SP arrangement is different for each layer (the sign relation between layers may also be different) (in the illustrated example, Dy=2 in layers A and B, and Dy in layer C). = 4), the equalizer 175P obtained by simply replacing the OFDM frame head detector 1751P shown in FIG. 4 with the SP head detector 1751 shown in FIG. Since equalization is performed on the basis of symbols, the periodicity of SP (non-sign inversion) and SP (sign inversion) cannot be maintained, and in this example, only the frequency characteristic of layer C becomes nonlinear (right side of FIG. 6). middle diagram), and the measurement of the C layer constellation becomes unstable (see the lower right diagram in FIG. 6).

Note that the left middle diagram and right middle diagram of FIG. 6 also show the frequency characteristics of all the layers A, B, and C combined in the same manner as in FIG. Similarly to FIG. 5 , the constellation in the case of vertically polarized waves in the C layer is illustrated with the horizontal axis and the vertical axis being the I axis and the Q axis, respectively.

That is, even if the equalization unit 175P simply replaces the OFDM frame start detection unit 1751P shown in FIG. 4 with the SP start detection unit 1751 shown in FIG. ) are present at predetermined intervals in the symbol direction. Therefore, if the SP arrangement for each layer is the same, the sign of the SP for each layer is the same, so the propagation path can be estimated without problems.

However, in the equalization unit 175P in which the OFDM frame head detection unit 1751P shown in FIG. 4 is simply replaced with the SP head detection unit 1751 shown in FIG. Since the positive and negative signs of SPs for each layer may differ, segments with different positive and negative SP signs are inverted in the frequency characteristics obtained by estimating the propagation path, and OFDM demodulation cannot be performed correctly. .

In other words, when the SP arrangement is different for each layer, the code at the beginning of the SP in the lowest layer (layer C) and the SP in the layer above it (layer A and layer B) may be different in the same symbol. , the frequency characteristics are not linear if the propagation path is estimated from the leading symbol of the SP signal and the frequency characteristics are obtained. As shown in the right diagram of FIG. 6, for example, if the sign of the SP in the lowest layer (C layer) is inverted, the frequency characteristic is such that the sign of the signal in the lowest layer (C layer) is inverted. The constellation of a signal equalized using is not demodulated correctly.

Therefore, the equalizer 175 of the embodiment according to the present invention shown in FIG. 3 has a smaller buffer capacity than the equalizer 175P (described later with reference to FIG. 4) based on the prior art. A memory 1752, and an SP head detection unit 1751 that detects the head symbol of the SP signal (SP symbol at the head of the carrier number) instead of detecting the head of the OFDM frame. A characteristic converter 1755 is provided.

(Control of frequency characteristic conversion section in equalization section of one embodiment according to the present invention)
FIG. 7 is a flow chart showing control of the frequency characteristic conversion section 1755 during MIMO transmission provided in the equalization section 175 of one example in the OFDM signal measuring apparatus 1 of one embodiment according to the present invention. 8A to 8D are diagrams for explaining the control of the frequency characteristic converter 1775. FIG.

As shown in FIG. 7, the frequency characteristic conversion unit 1775 first inputs an OFDM signal after SP interpolation processing in the time direction, and converts the OFDM signal with the frequency characteristic of the SP signal as a "first frequency characteristic". Temporarily hold (step S1).

Subsequently, the frequency characteristic conversion unit 1755 determines from the TMCC information whether or not there is a layer in which the SP signal having the first frequency characteristic may undergo sign inversion and the periodicity of the sign inversion. For the SP signal of the hierarchy determined as, in the predetermined symbol period (20 symbol periods), the SP (sign-inverted) symbol is multiplied by -1 according to the determined periodicity and converted to an SP (non-sign-inverted) symbol. (step S2). For example, assuming that only the frequency characteristic of layer C is nonlinear as the first frequency characteristic of the input SP signal as shown in FIG. , the positive/negative sign of the sign-inverted SP symbol of layer C is inverted to generate the second frequency characteristic from the first frequency characteristic.

As described with reference to FIG. 10, during MIMO transmission, the leading SP symbol of the OFDM frame of system 2 is obtained by multiplying the leading SP symbol of the OFDM frame of system 1 by +1 (non-coded Inversion), based on the SP symbol at the beginning of this OFDM frame, the code of the SP symbol in the symbol direction (time direction) and carrier direction (frequency direction) in the carrier-symbol space defined based on the carrier interval Dx and the symbol interval Dy Alternately inverts the values. The SP arrangement of system 2 is obtained by arranging the basic blocks of the carrier-symbol space including the SP symbol at the beginning of the OFDM frame by alternately inverting the sign of the SP symbol in basic block units in the carrier direction and the symbol direction. is. Whether or not the code inversion method is adopted is described in the TMCC information so that the receiving side can discriminate.

Subsequently, the frequency characteristic conversion unit 1755 converts the "first frequency characteristic" into a "second frequency characteristic" by inverting the sign of the SP symbol based on the determination, and converts the second frequency characteristic is once generated and temporarily held (step S3).

Subsequently, the frequency characteristic converter 1755 compares the first and second frequency characteristics and selects an OFDM signal having more linearly continuous frequency characteristics.

More specifically, the frequency characteristic conversion unit 1755 calculates the sum of amplitude distances between adjacent SP symbols in the carrier direction in the hierarchy for each of the first and second frequency characteristics (step S4). For example, as shown in FIG. 8(c), the frequency characteristic conversion unit 1755 converts SP symbols adjacent in the carrier direction in all layers for each polarization of MIMO transmission with respect to the first frequency characteristic shown in FIG. 8(a). In addition to calculating the sum of the amplitude distances between, as shown in FIG. 8(d), for the second frequency characteristics shown in FIG. Calculate the sum of amplitude distances between SP symbols. 8(c) and (d) are enlarged illustrations of SP symbols appearing at the boundary between the A layer (or B layer) and the C layer. 4 illustrates the non-linear frequency characteristics compared to .

Finally, the frequency characteristic conversion unit 1755 determines that the frequency characteristic with the smaller sum of the amplitude distances is the linearly continuous frequency characteristic among the first and second frequency characteristics, and determines that the frequency characteristic is more linearly continuous. It selects the OFDM signal that it has and outputs it to the SP frequency direction interpolator 1756 (step S5). The SP arrangement can know the sign-inverted hierarchy from the TMCC information, but which of the non-linear frequency characteristic and the linear frequency characteristic appears first changes depending on the leading symbol of the detected SP signal. It will be. That is, if the codes of the leading symbols of the detected SP signals for each layer are aligned, the linear frequency characteristics appear first, but if they are not aligned, the nonlinear frequency characteristics appear first, so steps S4 and S5. verification process is required.

In this way, the frequency characteristic conversion unit 1755 determines whether the codes of the leading symbols of the SP signals on the same symbol of the OFDM signals after the SP interpolation processing in the time direction are the same or different for each layer. When the signal has nonlinear frequency characteristics, the SP signal is converted into an OFDM signal having linearly continuous frequency characteristics.

Therefore, the equalization unit 175 of the embodiment according to the present invention shown in FIG. 3 having the frequency characteristic conversion unit 1755 analyzes the OFDM signal for a predetermined symbol period (20 symbol periods in this example) from the leading symbol of the SP signal. Even so, for example, when the SP arrangement is the same for each layer (the code relation between layers is also the same) as shown in the upper left diagram of FIG. As shown in the upper right figure, when the SP arrangement is different for each layer (the code relation between layers may also be different) (in the illustrated example, Dy=2 in layers A and B, and Dy=4 in layer C), In either case, all the frequency characteristics of each layer (A layer, B layer, and C layer) can be linearly continuous (see the left middle diagram and the right middle diagram in FIG. 9).

Since a linearly continuous frequency characteristic can be obtained, as a result, the signal constellation equalized using this frequency characteristic is as shown in the lower left and lower right diagrams of FIG. correctly obtained. Therefore, even when analyzing an OFDM signal for a predetermined symbol period (20 symbol periods in this example, which is shorter than one OFDM frame) from the first symbol of the SP signal, the SP arrangement and code relationship are the same for each layer. Measurements of the constellations of the A layer, the B layer, and the C layer can also be stably obtained regardless of whether or not the constellation is. The left middle diagram and right middle diagram of FIG. 9 also show the frequency characteristics of all the layers A, B, and C combined as in FIG. Similarly to FIG. 6, the constellation in the case of vertically polarized waves in the C hierarchy is illustrated with the horizontal axis and the vertical axis being the I axis and the Q axis, respectively.

As a result, the equalization unit 175 of the embodiment according to the present invention shown in FIG. 3 performs a predetermined symbol period (20 symbol periods in this example, shorter than one OFDM frame) from the first symbol of the SP signal. Even in OFDM signal analysis, whether the SP arrangement is the same or different for each layer, it is possible to form an OFDM signal with linearly continuous frequency characteristics, and a stable constellation can be obtained. Obtainable.

Therefore, according to the measuring apparatus 1 of the present embodiment, even if the SP arrangement differs for each hierarchy, it is possible to measure a MIMO-OFDM signal at a lower cost and in a shorter time. In other words, according to the measurement apparatus 1 of the present embodiment, detection of the beginning of the OFDM frame is not required, so the necessary programs and hardware are not required, and the buffer memory for signal analysis of the MIMO-OFDM signal is not required. The buffer capacity can be reduced, and the analysis time can be shortened.

Regarding the examples of the respective embodiments described above, a computer that functions as the signal analysis unit 17 or the signal analysis unit 17 and the data collection unit 18 of the measuring device 1 is configured, and a program for functioning each means of these devices is suitable. can be used for Specifically, a control unit for controlling each means can be configured by a central processing unit (CPU) in a computer, and at least a storage unit for appropriately storing programs required to operate each means It can be configured with one memory. That is, by causing the CPU of such a computer to execute the program, the functions of the above-described means can be realized. Further, a program for realizing the function of each means can be stored in a predetermined area of the aforementioned storage section (memory). Such a storage unit can be configured with a RAM or ROM inside the device, or can be configured with an external storage device (eg, hard disk). Also, such a program can be made up of a part of software (stored in a ROM or an external storage device) on an OS used in a computer. Furthermore, a program for causing such a computer to function as each means can be recorded on a computer-readable recording medium. Moreover, each of the means described above can be configured as a part of hardware or software, and can be realized by combining them.

Although each of the above embodiments has been described as a representative example, it will be apparent to those skilled in the art that many modifications and substitutions can be made within the spirit and scope of the invention. For example, in the above description, the measuring apparatus 1 mainly measures MIMO OFDM signals, but it can also be used to measure MISO OFDM signals and SISO OFDM signals. Therefore, the present invention should not be construed as limited by the above-described embodiments, but only by the claims.

INDUSTRIAL APPLICABILITY The present invention is useful for measuring OFDM signals of next-generation terrestrial broadcasting.

1 measuring device 11, 12 received power measurement unit 13, 14 frequency conversion unit 15, 16 analog/digital (A/D) conversion unit 17 signal analysis unit 17H horizontal polarization signal analysis unit 17V vertical polarization signal analysis unit 17C Condition number calculation unit 18 Data collection unit 170 Data input/output unit 171 Synchronization reproduction unit 172 TMCC decoding unit 173 Control information reading unit 175 Equalization unit 175P Equalization unit in the prior art 176 Signal separation unit 177 Deinterleaving unit 178 Layer separation unit 179A , 179B, 179C MER calculation unit 181 display unit 182 operation unit 183 recording unit 1751 SP head detection unit 1751P OFDM frame head detection unit in conventional technology 1752 buffer memory 1752P buffer memory in conventional technology 1753 SP complex division unit 1754 SP time direction interpolation unit 1755 frequency characteristic conversion unit 1756 SP frequency direction interpolation unit 1757 complex division unit 1758 data output unit

Claims (5)

A measuring device for measuring OFDM signals, comprising:
Measurement including at least a frequency characteristic based on a scattered pilot (SP) signal for each layer in an OFDM signal after MIMO transmission, and a constellation of a data signal in the OFDM signal Equipped with signal analysis means for analyzing and measuring values,
The signal analysis means comprises equalization means for executing equalization processing for correcting the OFDM signal based on the SP signal for each layer in the OFDM signal after synchronous reproduction,
The equalization means is
Two types of SP constellations: the signal point constellation of the SP signal of system 1 and the signal point constellation of the SP signal of system 2 obtained by regularly inverting the sign of a predetermined SP symbol with respect to the signal point constellation of the SP signal of system 1. SP head detection means for detecting the head symbol of the SP signal for each layer from the OFDM signal after synchronization regeneration during MIMO transmission having a pattern;
a buffer memory for storing an OFDM signal for a predetermined symbol period from the head symbol of the SP signal;
SP complex division means for performing complex division on the OFDM signal for the predetermined symbol period and estimating an amplitude/phase change amount of the SP signal by a predetermined channel estimation;
SP time direction interpolation means for executing SP interpolation processing in the time direction using the amplitude/phase change amount;
frequency characteristic conversion means for converting the OFDM signal after the SP interpolation processing in the time direction into an OFDM signal having a frequency characteristic in which the SP signal is linearly continuous when the SP signal has a nonlinear frequency characteristic;
SP frequency direction interpolation means for performing SP interpolation processing in the frequency direction on the OFDM signal obtained from the frequency characteristic conversion means;
complex division means for correcting the OFDM signal by performing complex division on the OFDM signal after the SP interpolation processing in the frequency direction;
A measuring device comprising: The frequency characteristic conversion means determines whether the codes of the leading symbols of the SP signals on the same symbol of the OFDM signals after the SP interpolation processing in the time direction are the same or different for each layer, and the SP signals are non-linear. 2. The measuring apparatus according to claim 1, wherein when the SP signal has a frequency characteristic, it is converted into an OFDM signal having a linearly continuous frequency characteristic. The frequency characteristic converting means may set the frequency characteristic of the SP signal in the OFDM signal after the SP interpolation processing in the time direction as a first frequency characteristic, and may invert the sign of the SP signal having the first frequency characteristic. The presence or absence of a layer and the periodicity of sign inversion are determined from the TMCC information, and for the SP signal of the layer determined to have the possibility of sign inversion, the sign is inverted according to the determined periodicity for the predetermined symbol period. the SP symbol is converted to a non-sign-inverted SP symbol into a second frequency characteristic in which the sign is inverted, and the first and second frequency characteristics are compared to obtain a linearly continuous frequency characteristic. 3. The measuring apparatus according to claim 1, wherein an OFDM signal is selected and output to said SP frequency direction interpolating means. The frequency characteristic converting means calculates a sum of amplitude distances between adjacent SP symbols in a carrier direction for each of the first and second frequency characteristics, 4. The measuring apparatus according to claim 3, wherein the smaller sum of distances is determined to have linearly continuous frequency characteristics, and an OFDM signal having more linearly continuous frequency characteristics is selected and output. . A program for causing a computer to function as the signal analysis means in the measuring apparatus according to any one of claims 1 to 4.