JP4697774B2 - Signal level adjusting device, communication device, and signal level adjusting method - Google Patents

Description

  The present invention relates to a signal level adjusting device and a signal level adjusting method for analyzing the frequency characteristics of an unbalanced component in a transmission path through which a multicarrier communication signal is transmitted, and a communication device of a multicarrier communication system.

  Conventionally, balanced transmission systems that perform data transmission using a pair of transmission lines in a balanced state have been widely used. In this type of balanced transmission system, a transmission line such as a dedicated communication line is often used, such as a telephone line, and a certain degree of balance is usually maintained.

  Recently, there has been proposed a power line communication system that performs data transmission by superimposing a high-frequency signal on a power line that carries power such as a commercial power source. As this type of power line communication system, a multicarrier communication system communication device that transmits and receives multicarrier communication signals is known (see, for example, Patent Document 1). A power line used as a transmission line in a power line communication system is not originally a communication line. Therefore, the degree of balance may vary depending on the wiring situation in each house, the equipment connected to the power source, and the like. For this reason, when a power line is used as a transmission line, the degree of balance may change depending on each environment, and transmission characteristics may be greatly different.

  When performing power line communication in multi-carrier communication system, the common mode current and radiation noise are measured to detect the frequency component corresponding to each carrier as an amount indicating the degree of balance in the transmission path. By reducing the output level of the large carrier frequency band, radiation can be reduced. In addition, by increasing the output level in the frequency band of carriers with small common mode current and radiation noise, it is possible to use multi-level modulation in communication data and increase the amount of data transmission per unit time. And stable communication at higher speed.

  By the way, in the power line communication, when there is an existing communication system or the like in the used frequency band, it is possible to mask the carriers in the frequency band in advance, that is, to provide a notch in some frequency bands of a plurality of carriers for transmission. Has been made.

  In order to detect the frequency component of each carrier with respect to the unbalanced component of the transmission line, the common mode current and radiation noise in the transmission line are converted into a digital signal, and the value on the frequency axis using FFT (Fast Fourier Transform). It is necessary to use a method such as calculating the level for each carrier after conversion into However, processing such as FFT takes a lot of time, and there is a situation that it cannot cope with high-speed processing such as real-time analysis. Therefore, instead of calculating the level of the unbalanced component for each carrier for all carriers, the number of carriers for calculating the unbalanced component is reduced and processing is performed with the carriers thinned out. A method is also conceivable in which the level of the unbalanced component of another carrier is estimated based on the level of the unbalanced component.

  Here, when the level of the unbalanced component is calculated for the notch band in which no carrier is transmitted, the calculation result is a low value. If the low value calculated in the notch band is assigned as the level of the unbalanced component of the carrier adjacent to the notch band, the detection result of this adjacent carrier will be smaller than the actual value, and the output level (transmission level) will be Control to increase is performed, and a problem that the output level of the carrier becomes excessively higher than an appropriate value occurs.

JP 2003-218831 A

  The present invention has been made in view of the above circumstances. When analyzing the frequency characteristics of unbalanced components in a transmission path for multicarrier communication, if there is a notch band that does not transmit a predetermined carrier, An object of the present invention is to provide a signal level adjusting device, a communication device, and a signal level adjusting method capable of preventing erroneous detection of an unbalanced component of a carrier.

The signal level adjusting apparatus of the present invention is a signal level adjusting apparatus that adjusts the signal level of a multicarrier communication signal composed of a plurality of carriers in accordance with an unbalanced component in a transmission line, and the signal level adjusting apparatus performs the above-mentioned unbalance by time-frequency conversion. A time-frequency conversion unit that calculates the signal level of the balanced component on the frequency axis, and a signal level of the unbalanced component calculated by the time-frequency conversion unit, are not calculated by the time-frequency conversion unit. A signal level estimator for estimating the signal level of the balanced component; and a waveform generator for generating the multicarrier communication signal based on the signal level of the unbalanced component estimated by the signal level estimator. The level estimation unit uses the signal level of the unbalanced component calculated by the time-frequency conversion unit, and does not transmit a predetermined carrier. Outside Chi band, and estimates the signal level of the unbalanced component.

In the above configuration, by using the signal level of the unbalanced component calculated by the time-frequency conversion unit, the signal level of the unbalanced component in the frequency band outside the notch band that does not transmit a predetermined carrier is estimated, thereby notch band. Even if there is, it is possible to prevent erroneous detection of an unbalanced component of a carrier adjacent to this notch band.

  Further, the present invention is the above-described signal level adjustment device, wherein the signal level estimation unit includes a detected carrier, which is a carrier whose signal level of an unbalanced component is calculated by the time-frequency conversion unit, in the notch band. When located, a signal of an undetected carrier which is a carrier whose signal level of an unbalanced component is not calculated by the time-frequency conversion unit using a signal level of a detected carrier that is outside the notch band adjacent to or adjacent to the notch band. The level is estimated.

  In the above configuration, when the signal level estimation unit estimates the signal level of the non-detected carrier, if the detected carrier is located in a notch band that does not transmit a carrier in the multicarrier communication signal, the notch band adjacent to or near this notch band. Even if there is a notch band, an error in the unbalanced component of the carrier adjacent to the notch band is detected by estimating the level of the undetected carrier near the notch band using the signal level of the detected carrier outside. Detection can be prevented.

  Further, the present invention is the signal level adjustment device described above, wherein the signal level estimation unit includes N detection carriers (N is an integer of 1 or more) and a number (a is 1 or more) adjacent thereto. A maximum value or an average value of the signal levels calculated by these detected carriers, and this value is calculated between the N detected carriers and the N detected carriers. The level estimation values of the non-detected carrier and the non-detected carrier adjacent to the a number of detected carriers are used.

  With the above configuration, by appropriately setting the number of detected carriers N and a used for level estimation, even if there is a notch band, the maximum or average value can be obtained using the signal level of the detected carrier outside the notch band. It is possible to calculate and use this value as a level estimation value of the non-detection carrier between or adjacent to the detection carriers, and an appropriate level estimation value can be obtained.

  Also, the present invention is the above signal level adjustment device, wherein the signal level estimation unit is calculated with N detection carriers (N is an integer of 1 or more) that is wider than the width of the notch band. The maximum value or average value of the detected signal levels is obtained, and this value is used as the level estimation value of the N detected carriers and the non-detected carrier among the N detected carriers.

  With the above configuration, the maximum value or the average value is calculated using the signal level of the detected carrier in a range wider than the width of the notch band, and this value is used as the level estimated value of the non-detected carrier between or adjacent to the detected carriers. And an appropriate level estimate can be obtained.

  Further, the present invention is the above-described signal level adjustment device, wherein the signal level estimation unit is a non-detected carrier in the vicinity of the notch band, and a detection carrier having a high frequency or a low frequency immediately outside the notch band. Using the calculated signal level, this value is used as the level estimation value of the undetected carrier.

  With the above configuration, when performing level estimation of the non-detected carrier in the vicinity of the notch band, by performing level estimation using the signal level calculated with the latest high frequency or low frequency detected carrier outside this notch band, An appropriate level estimation value can be obtained.

  Further, the present invention is the above-described signal level adjusting device, wherein the signal level estimation unit is configured to calculate, in the non-detected carrier, the signal level calculated by using a detected carrier having a frequency close to the non-detected carrier and a low frequency. Is the level estimated value, and in the detected carrier, the signal level calculated by the detected carrier is directly used as the level estimated value.

  With the above configuration, in the non-detected carrier, level estimation is performed using the signal level calculated in the latest high frequency and low frequency detected carriers of the non-detected carrier, and in the detected carrier, the signal calculated in the detected carrier. By using the level as the level estimation value as it is, it is possible to appropriately estimate the level of the non-detected carrier in the vicinity of the notch band even when there is a notch band.

  Further, the present invention provides any one of the above signal level adjusting devices, wherein digital data of an unbalanced component detection signal in the transmission path is input, and the number of points when performing time-frequency conversion of the digital data is calculated. A pre-processing unit that performs pre-processing to reduce the number of carriers of the multi-carrier communication signal, and the time-frequency conversion unit performs time-frequency conversion on the unbalanced component digital data with the reduced number of points. Is.

  With the above configuration, by providing a preprocessing unit, it is possible to prevent the phase and amplitude components of other frequency bands (carriers) from affecting the calculation result of time-frequency conversion, and to calculate an accurate signal level. Become.

  A communication apparatus according to the present invention includes any one of the signal level adjustment apparatuses described above, and includes a transmission unit that adjusts and outputs a transmission level for each carrier of the multicarrier communication signal by the signal level adjustment apparatus. .

  In the above configuration, by adjusting the transmission level for each carrier of the multicarrier communication signal based on the detection result of each frequency component related to the unbalanced component of the transmission path, while reducing the radiation level from the transmission path, It becomes possible to keep the transmission level for each carrier as large as possible. Even if there is a notch band, an appropriate value can be obtained as the detection result of the unbalanced component for which level estimation has been performed, so the level estimation using the detection carrier in the notch band results in a small detection value, and transmission Problems such as the level being controlled to be larger than the appropriate value can be eliminated.

The signal level adjustment method of the present invention is a signal level adjustment method for adjusting the signal level of a multicarrier communication signal composed of a plurality of carriers in accordance with an unbalanced component in a transmission path, which is performed by time-frequency conversion. Using the step of calculating the signal level of the unbalanced component on the frequency axis and the signal level of the unbalanced component calculated by the time-frequency conversion, the signal of the unbalanced component not calculated by the time-frequency conversion Estimating the level, and generating the multi-carrier communication signal based on the estimated signal level of the unbalanced component, and estimating the signal level of the unbalanced component in the time - using the signal level of the unbalanced components calculated by the frequency conversion, the outer notch band not transmit predetermined carrier And estimates the signal level of the unbalanced component.

  According to the present invention, when there is a notch band that does not transmit a predetermined carrier when analyzing the frequency characteristics of the unbalanced component in the transmission path for multicarrier communication, erroneous detection of the unbalanced component of the carrier around the notch band is performed. Can be prevented.

  In an embodiment of the present invention, in a balanced transmission system that performs data transmission through a balanced transmission line, a signal level adjustment device that adjusts the signal level of a multicarrier communication signal according to an unbalanced component in the transmission line, and the signal level adjustment device In addition, a configuration example of a communication device including a transmission unit and a reception unit is shown. The signal level adjusting device of this embodiment is suitably used for a balanced transmission system such as a power line communication system using a power line as a transmission path. Further, the data communication can be applied to data communication such as power line communication using frequency division multiplexing signals, OFDM (Orthogonal Frequency Division Multiplexing), or ADSL (Asymmetric Digital Subscriber Line).

  FIG. 1 is a block diagram showing a configuration of a communication apparatus according to an embodiment of the present invention. The communication device 1 according to the present embodiment is a communication device of a power line communication system that uses a power line 10 such as a residential power line as a transmission line and transmits and receives data by a multicarrier communication method using OFDM or the like. Used as The communication device 1 includes an unbalanced component analyzer 2 that detects an unbalanced component of the power line 10 and analyzes its frequency characteristics, a transmitter 3 that transmits data, a receiver 4 that receives data, The transmission unit 3 and the reception unit 4 are configured to include a coupling transformer 5 that couples the power line 10.

  The unbalanced component analyzing unit 2 includes an unbalanced component detecting unit 21 that detects a common mode current in the power line 10, and an A / D converting unit 22 that converts the common mode current detected by the unbalanced component detecting unit 21 into digital data. The FFT preprocessing unit (preprocessing unit) 23 that performs preprocessing when performing FFT (Fast Fourier Transform) on the output of the A / D conversion unit 22 and the output of the FFT preprocessing unit 23 are subjected to FFT processing. An FFT unit (time-frequency conversion unit) 24 that performs time-frequency conversion, calculates a detection value on the frequency axis of the common mode current, and performs frequency analysis, and an unbalance in a detection carrier obtained as an output of the FFT unit 24 Based on the level detection result of the component, the level estimation unit 25 that estimates the level of the unbalanced component of the other undetected carrier, and the detection result of the unbalanced component using the level estimated value of the unbalanced component To configured to have a detection result output unit 26 for outputting. Note that FFT is an example of time-frequency conversion, and is not necessarily limited thereto.

  The unbalanced component detection unit 21 detects the unbalanced component of the transmission line by detecting the common mode current of the power line 10 composed of a pair of transmission conductors using a transformer, a resistance bridge, an ammeter, a voltmeter, or the like. To do. The FFT preprocessing unit 23 has a function of reducing the number of FFT points in the subsequent stage by performing addition processing or subtraction processing on data of a predetermined sampling number that has been A / D converted by the A / D conversion unit 22.

  The FFT unit 24 converts detection data on the time axis of the unbalanced component into data on the frequency axis by FFT, and detects the signal level of the unbalanced component for each frequency band corresponding to a plurality of carriers of the multicarrier communication signal. Calculate as a value. At this time, the FFT preprocessing unit 23 performs the FFT of the reduced number of points, thereby reducing the FFT processing amount and enabling the FFT processing to be executed in a short time.

  Based on the detection result in the frequency band of the carrier (detected carrier) for which the signal level of the unbalanced component is calculated by the FFT unit 24, the level estimation unit 25 performs unbalance by FFT processing in which the number of points in the FFT unit 24 is reduced. The signal level of the unbalanced component is estimated for the frequency band of the carrier (non-detected carrier) for which the component signal level is not calculated. The detection result output unit 26 stores the unbalanced component level of each carrier in association with information such as the carrier frequency by using the level estimation value estimated by the level estimation unit 25, and detects the unbalanced component for all carriers. Output as a result. This detection result is obtained as the amplitude of the common mode current for each carrier on the frequency axis, and is supplied to the transmitter 3.

  The transmission unit 3 includes a waveform generation unit 31 that generates a transmission waveform, an amplification unit 32 that amplifies or attenuates the transmission waveform, and a notch information storage unit 33 that stores information of a frequency band (notch band) that does not transmit a carrier. It is configured. The information on the notch band is supplied to the waveform generation unit 31 and is also supplied to the level estimation unit 25 in the unbalanced component analysis unit 2.

  The waveform generator 31 controls the transmission level for each carrier. Specifically, when the value of the unbalanced component of each carrier output from the detection result output unit 26 exceeds a preset threshold A (power down threshold), the transmission level of that carrier is set to a predetermined amount. Reduce. If the value of the unbalanced component of each carrier is smaller than a preset threshold B (power-up threshold), the carrier transmission level is increased by a predetermined amount. The threshold A is set to a value larger than the threshold B. Thereby, the common mode current for each carrier is reduced, and the transmission level for each carrier can be kept large while preventing the radiation level from the transmission path from becoming excessive. Note that the signal level adjustment apparatus according to the present embodiment includes the unbalanced component analysis unit 2 (at least the FFT unit 23 and the level estimation unit 25) and the waveform generation unit 31 of the transmission unit 3.

  In the above configuration example, the FFT preprocessing unit 23 is provided, but the FFT preprocessing unit is not necessarily provided. It is possible to reduce the number of points in the FFT without providing an FFT preprocessing unit. For example, in the case of an apparatus that does not require a calculation result with very high accuracy in detection of an unbalanced component and subsequent signal level adjustment, the circuit configuration related to the FFT preprocessing unit is not provided by not providing the FFT preprocessing unit. Simplification and reduction of processing time can be achieved.

  FIG. 2 is a diagram illustrating an example of a transmission signal waveform and a common mode current waveform. In the transmission line of the power line communication system, the common mode corresponding to the frequency characteristic of the unbalanced component of the power line 10 is shown in FIG. 2B for the multicarrier transmission signal shown in FIG. A current is generated.

FIG. 3 is a diagram showing detection points for detecting unbalanced components and interpolation points for interpolating detection results. FIG. 3 shows operations of the level estimation unit 25 and the detection result output unit 26 that estimate and interpolate the level of the unbalanced component of the undetected carrier based on the detection result of the detected carrier. The unbalanced component analysis unit 2 performs the FFT in the FFT unit 24 with the number of FFT points being 1 / ²ⁿ of the number of carriers. FIG. 3 shows an example in which the detection result of the latest detected carrier having a high frequency is assigned to the non-detected carrier and estimated. As shown in FIG. 3A, when n = 1, half (1/2) carriers are detection points (indicated by black circles) corresponding to detected carriers. In this case, the detection result of the adjacent detection point on the higher frequency side is assigned to the interpolation point (indicated by a white circle) corresponding to the non-detected carrier. As shown in FIG. 3B, when n = 2, 1/4 of the total number of carriers is a detection point (detection carrier). In this case, the detection result of the adjacent detection point on the higher frequency side is assigned to the interpolation point (non-detected carrier, three consecutive carriers). In this way, for a non-detected carrier for which a detection result cannot be obtained by thinning out the number of FFT samples, the signal level is estimated by interpolation based on the detection result of the detected carrier.

  FIG. 4 is a diagram showing an operation of reducing the number of FFT points by addition processing and taking out only the components of even-numbered harmonics to eliminate the influence of adjacent carriers. FIG. 4 shows an analog signal waveform image (that is, a waveform image showing each frequency component), but it is actually realized by a digital data calculation process. As shown in FIGS. 4A to 4D, the number of samplings is obtained by adding the data of the first half (1 to k / 2) and the data of the second half (k / 2 + 1 to k) of the sampling number k, respectively. The odd period signal at k is canceled out and the even period signal is doubled in amplitude. Therefore, the first half data and the second half data of the sampling number k are added and the amplitude is halved to extract only the signal components of even-numbered harmonics at the sampling number k, and the sampling number is k / 2. And can be halved.

  For the signal of the even period, each data of the first quarter (1 to k / 4) of the first half of the sampling number k, the next quarter (k / 4 + 1 to k / 2), and the second half By adding the first quarter (k / 2 + 1 to 3k / 4) data and the next quarter (3k / 4 + 1 to k) data, only the signal component of the fourth harmonic Can also be taken out.

  Further, by subtracting each data of the first half (1 to k / 2) and each data of the second half (k / 2 + 1 to k) of the sampling number k, the signal of the even period in the sampling number k is canceled, and the odd period The signal is doubled in amplitude. Therefore, by subtracting the first half data and the second half data of the sampling number k and halving the amplitude, it is possible to extract only the signal component of the odd multiple wave at the sampling number k.

  FIG. 5 is a diagram illustrating an example of the FFT preprocessing unit. In this example, the number of FFT points is reduced by addition processing. The FFT preprocessing unit 23 </ b> A includes a k / 2-stage shift register 231 and an adder 232. In this configuration, the adder 232 adds sampling data of k sample periods (a period in which the sampling period is k) and sampling data shifted by k / 2 stages by the k / 2 stage shift register 231. The first half (1 to k / 2) data of the sampling number k and the second half (k / 2 + 1 to k) data are added. Then, the FFT of the number of points halved to k / 2 is executed by the subsequent FFT unit 24A. As a result, the influence of adjacent carriers can be removed while reducing the number of FFT points, and the amplitude of the desired carrier can be accurately detected. In addition, since the number of FFT points is halved, the processing time required to analyze the frequency characteristics can be shortened.

  FIG. 6 is a diagram illustrating a specific example of a transmission carrier having a notch band. FIG. 6 shows an example of a transmission wave composed of 400 carriers on the frequency axis as a transmission carrier for performing multicarrier communication by wavelet OFDM. Note that the lower side of FIG. 6 indicates carrier numbers 0 to 399. In the illustrated example, there is a notch band in which there are no four carriers of carrier numbers n + 2 to n + 5.

  FIG. 7 is a diagram illustrating a specific example of the detection result of the unbalanced component by FFT. Here, it is assumed that the detection value of the signal level of the unbalanced component is obtained by FFT in the FFT unit 24 for every 100 carriers out of the 400 carriers shown in FIG. In addition, the lower side of FIG. 7 has shown the FFT number of 0-99. In the illustrated example, detection values of signal levels are obtained for every fourth detection carrier, and the detection level of the FFT number X corresponding to the notch band is 0 due to the influence of the adjacent detection carrier. It is getting bigger.

  FIG. 8 is a diagram for explaining problems in the operation of level estimation in the level estimation unit 25 and transmission level control in the waveform generation unit 31. When the detection result of a detected carrier in the notch band is applied to a non-detected carrier in a non-notch band (normal carrier band) adjacent to the notch band, the transmission level is increased by the detection value of the signal level having a small notch band. Control is performed, and there is a possibility that the transmission level of the carrier becomes excessively higher than an appropriate value. FIG. 8A shows a transmission carrier, which has a notch band. FIG. 8B shows the measured value of the unbalanced component corresponding to the transmission carrier shown in FIG. 8A. Since no carrier exists in the notch band, no unbalanced component is generated.

  FIG. 8C shows a signal level detection value that is the result of processing of the unbalanced component measurement value shown in FIG. 8B by the FFT unit 24, and a level estimation value of the undetected carrier by the level estimation unit 25. Is shown. In this example, the number of FFT points is set to 1/4 of the number of carriers, and the values corresponding to the FFT numbers (values indicated by vertical broken lines, that is, the values of the peaks of solid lines) are calculated by FFT. It becomes the detected value of the signal level of the unbalanced component in each detected carrier. Then, as shown by the thick lines extending in the horizontal direction from the respective detected values in FIG. 8C, the three detected non-detected carriers on the frequency side higher than the respective detected carriers are the same as the detected values of the detected carriers. Is the estimated level of the unbalanced component.

  The waveform generation unit 31 of the transmission unit 5 controls the transmission level to be lowered by a predetermined amount when the value of the unbalanced component of each carrier exceeds the threshold A, and when the value is smaller than the threshold B, the transmission level is reduced to the predetermined amount. Control to raise. When the detected carrier is a notch band, the detected value of the signal level of the detected carrier in the notch band is lower than the threshold value B. Therefore, this low value is used to estimate the level of the unbalanced components of the three adjacent non-detected carriers. If assigned as a value, it differs from the actual value of the unbalanced component on the undetected carrier. FIG. 8D shows a transmission carrier after transmission level control. As shown in the figure, the transmission level of the carrier whose detected value or level estimated value of the unbalanced component exceeds the threshold A is reduced, and the detected value or estimated level of the unbalanced component signal level is lower than the threshold B. Smaller carriers have an increased transmission level. As a result of this control, as shown in FIG. 8E, the unbalanced component after the transmission level control is an unbalanced component in two undetected carriers having the same level estimated value as the detected value of the signal level in the notch band. The value of will increase.

  In order to avoid the above-described adverse effects, in this embodiment, when the level estimation unit 25 estimates the level of the unbalanced component of the non-detected carrier, the non-detected carrier around the notch band detects the detected carrier in the notch band. A process for removing the influence of the detected signal level is performed.

  FIG. 9 is a diagram illustrating a first embodiment of operations in the level estimation unit 25 and the waveform generation unit 31. In the first embodiment, the maximum value or average of N + a detection carriers obtained by adding a detection carrier adjacent to N detection carriers as the level estimation value M of N detection carriers and non-detection carriers therebetween. A level estimation value M is set as a representative value of a corresponding estimation range (N detection carriers, non-detection carriers in between, and a detection carrier on the a detection carrier side) corresponding to this value. The transmission level of each carrier is controlled using M.

  In the first embodiment, there are notch bands for three carriers in the transmission carrier as shown in FIG. 9A, and the measured values of the unbalanced components corresponding to each transmission carrier as shown in FIG. 9B. Is obtained. At this time, the detected value of the signal level by the FFT processing in the FFT unit 24 is the value indicated by the vertical broken line in FIG. 9C, that is, the value of the peak of the solid line. Here, N = 1 and a = 1. The level estimation unit 25 performs N + a detection carriers, that is, a detection carrier of interest and one detection carrier on the higher frequency side in a total of two detection carriers in the direction of low frequency to high frequency on the frequency axis. Find the maximum or average value. Then, this value is set as a representative value of two corresponding detected carriers and three non-detected carriers between them, and this is set as a level estimation value M. FIG. 9 shows a case where the maximum value is used as the level estimation value M.

  When the above processing is repeated for all detected carriers in order from a low frequency to a high frequency, the level estimation value of each carrier is indicated by a thick line extending in the horizontal direction in FIG. 9C. The detection result output unit 26 stores the level estimation value of the unbalanced component obtained by the level estimation in association with information such as the frequency of each carrier, and outputs it as the detection result of the unbalanced component for all carriers.

  The waveform generator 31 controls the transmission level to increase by a predetermined amount when the value of the unbalanced component of each carrier exceeds the threshold A, and decreases the transmission level by a predetermined amount when the value is smaller than the threshold B. To control. In this case, since the detection result of the unbalanced component exceeds the threshold A in the high frequency band, as shown in FIG. 9D, a high unbalanced component is detected in the transmission carrier after the transmission level control. The transmission level of the carrier in the frequency band is lowered. As a result, as shown in FIG. 9E, the transmission level for each carrier is adjusted so that the unbalanced component after transmission level control falls within the appropriate range.

  FIG. 10 is a flowchart showing the processing procedure of the first embodiment of the operation in the level estimation unit 25 and the waveform generation unit 31. First, it is determined whether the processing of unbalanced component level estimation and transmission level control has been completed for all carriers (step S11). If not completed, the process proceeds to level estimation processing by the level estimation unit 25 in the next step S12. If it has been completed, this process ends. In step S12, the level estimation unit 25 obtains a maximum value or an average value among N + a (here, 2) detected carriers, and calculates this value as N (here, 1) detected carriers and non-intervals therebetween. This is set as the level estimate M of the detected carrier.

  Next, the waveform generation unit 31 determines whether or not the level estimation value M is larger than the threshold value A (step S13), and if it is larger, performs control to decrease the transmission level of the corresponding carrier (step S14). If the level estimation value M is less than or equal to the threshold A in step S13, it is determined whether or not the level estimation value M is smaller than the threshold B (step S15). If the level estimation value M is smaller, control is performed to increase the transmission level of the corresponding carrier. (Step S16). Then, based on the transmission level control result, the transmission levels of the detected carrier and the non-detected carrier within the estimation range that is the range in which the level estimation value M is set are determined (step S17). Thereafter, the process returns to step S11, and the above process is repeated until the process of estimating the unbalanced component level and the control of the transmission level is completed for all carriers.

  By performing the processing of the first embodiment, the level estimation value M of the non-detected carrier within the estimation range (within the N detected carriers for which level estimation is performed) is determined by the maximum value or the average value of the N + a detected carriers. It is determined. Therefore, by appropriately setting the values of N and a, even if a notch band exists, for example, the level estimation value M can be obtained within a range larger than the width of the notch band. Thus, it is possible to prevent the level estimation of the non-detected carrier outside the notch band from being performed based on the detected value of the signal level in the notch band. As a result, transmission level control based on the detection result of the unbalanced component can be performed appropriately, and it is possible to eliminate the problem that the transmission level is controlled to be larger than the appropriate range.

  In the above processing example, the operation of selecting N detection carriers and a detection carriers adjacent to them in the direction from low frequency to high frequency and determining the level estimation value M is shown. The same processing may be performed from the high frequency to the low frequency. In addition, the values of N and a for which the estimation range for performing level estimation is determined may be set as appropriate according to the installation state of the notch band, or may be variable depending on the width and frequency of the notch band. Is also possible. By setting the values of N and a according to the notch band and appropriately setting the estimation range, it is possible to finely control the transmission level for each carrier.

  FIG. 11 is a diagram illustrating a second embodiment of the operation in the level estimation unit 25 and the waveform generation unit 31. In the second embodiment, an estimation range in which level estimation is performed is set to be a range wider than the width of the notch band, a maximum value or an average value in N detection carriers within the estimation range is obtained, and this value is obtained as a level estimation value. This is set as M, and the transmission level of each carrier is controlled using the level estimation value M.

  In the second embodiment, there are notch bands for eight carriers in the transmission carrier as shown in FIG. 11A, and the measurement values of the unbalanced components corresponding to each transmission carrier as shown in FIG. 11B. Is obtained. At this time, the detected value of the signal level by the FFT processing in the FFT unit 24 is a value indicated by a vertical broken line in FIG. Here, since every fourth detected carrier, N = 3 (for nine carriers) so that the estimation range is wider than the notch band for eight carriers. The level estimation unit 25 includes a maximum value or an average value in three detection carriers on the frequency side including N detection carriers, that is, a detection carrier of interest, from a low frequency to a high frequency direction on the frequency axis. Ask for. Then, this value is set as a representative value of the corresponding three detected carriers and six non-detected carriers between them, and this is set as the level estimation value M. FIG. 11 shows a case where the maximum value is used as the level estimation value M.

  When the above processing is repeated for all detected carriers in order from a low frequency to a high frequency, the level estimation value of each carrier is as shown by a thick line extending in the horizontal direction in FIG. The detection result output unit 26 stores the level estimation value of the unbalanced component obtained by the level estimation in association with information such as the frequency of each carrier, and outputs it as the detection result of the unbalanced component for all carriers.

  The waveform generator 31 controls the transmission level to increase by a predetermined amount when the value of the unbalanced component of each carrier exceeds the threshold A, and decreases the transmission level by a predetermined amount when the value is smaller than the threshold B. To control. In this case, since the detection result of the unbalanced component exceeds the threshold A in the frequency band higher than the notch band, a large number of unbalanced components are detected in the transmission carrier after transmission level control as shown in FIG. The transmission level of the high frequency band carrier is reduced. As a result, as shown in FIG. 11E, the transmission level for each carrier is adjusted so that the unbalanced component after the transmission level control falls within an appropriate range.

  FIG. 12 is a flowchart showing the processing procedure of the second embodiment of the operation in the level estimation unit 25 and the waveform generation unit 31. First, it is determined whether or not the processing of unbalanced component level estimation and transmission level control has been completed for all carriers (step S21). If not completed, the process proceeds to level estimation processing by the level estimation unit 25 in the next step S22. If it has been completed, this process ends. In step S22, the level estimation unit 25 obtains a maximum value or an average value among N (here, 3) detected carriers, and sets this value as the level estimated value M of the detected carrier and the non-detected carrier in the meantime. To do.

  The subsequent processing of steps S23 to S27 is the same as the processing of steps S13 to S17 shown in FIG. 10, and the level estimation value M is determined by the waveform generation unit 31 by determining the level estimation value M and the threshold A and threshold B. When the value exceeds the thresholds A and B, the transmission level is adjusted to increase or decrease, and is determined as the transmission level of the detected carrier and the non-detected carrier within the estimated range.

  In the above-described processing example, the operation of selecting N detected carriers from the low frequency to the high frequency and determining the level estimation value M is shown. On the contrary, the same applies from the high frequency to the low frequency. You may make it perform the process of. In addition, when the width of the notch band is variable, by changing the value of N for which the estimation range for performing level estimation is determined, the estimation range can be varied in accordance with the width of the notch band, and appropriate level estimation is performed. It can be performed.

  By performing the processing of the second embodiment, the estimated range is a range of N detected carriers that is wider than the width of the notch band, and the level estimated value M of the non-detected carrier within this estimated range. Is determined by the maximum or average value of N detected carriers. For this reason, even when the detected carrier is located in the notch band, it is possible to prevent the level estimation of the non-detected carrier outside the notch band from being performed based on the detected value of the signal level in the notch band. As a result, transmission level control based on the detection result of the unbalanced component can be performed appropriately, and it is possible to eliminate the problem that the transmission level is controlled to be larger than the appropriate range. Further, in the second embodiment, since the processing procedure is simple, it is possible to execute the processing of carrier unbalanced component level estimation and transmission level control at high speed.

  FIG. 13 is a diagram illustrating a third embodiment of the operation in the level estimation unit 25 and the waveform generation unit 31. In the third embodiment, when the level of a non-detected carrier in the vicinity of the notch band is estimated when the detected carrier is located in the notch band, the signal level of the nearest high frequency or low frequency detected carrier adjacent to the notch band is used. This value is set as the level estimation value M.

  In the third embodiment, there are notch bands for three carriers in the transmission carrier as shown in FIG. 13A, and the measured values of the unbalanced components corresponding to each transmission carrier as shown in FIG. 13B. Is obtained. At this time, the detected value of the signal level by the FFT processing in the FFT unit 24 is the value indicated by the vertical broken line in FIG. 13C, that is, the value of the peak of the solid line. Here, the number of detected carriers that perform level estimation at a time is N = 1. The level estimation unit 25 obtains a maximum value or an average value in N detection carriers on the frequency side including the detection carrier of interest from a low frequency to a high frequency direction on the frequency axis. Since N = 1 here, the detected value of the signal level of the detected carrier is the maximum value and the average value, and this value is set as a representative value of the detected carrier and three non-detected carriers on the higher frequency side. This is set as the level estimation value M.

  The level estimation unit 25 refers to the notch band information stored in the notch information storage unit 33 to determine whether the detected carrier is a notch band. Here, in the case of the notch band, the detection value of the signal level of the nearest high frequency side detection carrier or the low frequency side detection carrier adjacent to the notch band is used, and this value is used as the detection carrier of the notch band. And the representative value of three non-detected carriers on the higher frequency side or lower frequency side is set as a representative value M. FIG. 13 shows a case where the detected value of the signal level of the detected carrier on the high frequency side is used as the level estimation value M.

  When the above processing is repeated for all detected carriers in order from a low frequency to a high frequency, the level estimation value of each carrier is as shown by a black dot on the detected carrier and a thick line extending in the horizontal direction in FIG. The detection result output unit 26 stores the level estimation value of the unbalanced component obtained by the level estimation in association with information such as the frequency of each carrier, and outputs it as the detection result of the unbalanced component for all carriers.

  The waveform generator 31 controls the transmission level to increase by a predetermined amount when the value of the unbalanced component of each carrier exceeds the threshold A, and decreases the transmission level by a predetermined amount when the value is smaller than the threshold B. To control. In this case, the detection result of the unbalanced component is lower than the threshold B in the low frequency band (band corresponding to FFT number 1) and exceeds the threshold A in the high frequency band (band corresponding to FFT number 99). 13 (D), in the transmission carrier after the transmission level control, the transmission level of the carrier in the low frequency band in which the unbalance component is detected to be small is raised, and the high frequency band in which the unbalance component is detected in a large amount. The carrier transmission level is lowered. As a result, as shown in FIG. 13E, the transmission level for each carrier is adjusted so that the unbalanced component after transmission level control falls within the appropriate range.

  FIG. 14 is a flowchart illustrating a processing procedure according to the third embodiment of the operations in the level estimation unit 25 and the waveform generation unit 31. First, it is determined whether unbalanced component level estimation and transmission level control processing has been completed for all carriers (step S31). If not completed, the process proceeds to level estimation processing by the level estimation unit 25 subsequent to step S32. If it has been completed, this processing is terminated. In step S32, the level estimation unit 25 obtains the maximum value or the average value among N (here, 1) detection carriers, and detects this value (here, the detection value of the signal level of the detection carrier). The representative value of the three non-detected carriers up to the carrier and the adjacent detected carrier on the higher frequency side is set as a level estimation value M.

  Further, the level estimation unit 25 refers to the notch band information and determines whether or not the detected carrier is a notch band (step S33). Here, when the detected carrier is in the notch band, the detected value of the signal level of the adjacent detected carrier on the higher frequency side or the detected carrier on the lower frequency side is used, and this value is used as the detected carrier in the notch band and A representative value of three non-detected carriers on the higher frequency side or lower frequency side is set as a representative value M and set as a level estimation value M (step S34).

  The subsequent processing of steps S35 to S39 is the same as the processing of steps S13 to S17 shown in FIG. 10, and the waveform generation unit 31 determines the level estimation value M by determining the level estimation value M and the threshold A and threshold B. When the value exceeds the thresholds A and B, the transmission level is adjusted to increase or decrease, and is determined as the transmission level of the detected carrier and the non-detected carrier within the estimated range.

  In the above-described processing example, the operation of selecting N detection carriers, determining the notch band, and determining the level estimation value M in the direction from the low frequency to the high frequency is shown. Similar processing may be performed in the frequency direction. Further, the level estimation may be performed based on the maximum value, the average value, or the like using the detection values of the signal level in both adjacent detection carriers on the high frequency side and the low frequency side.

  By performing the processing of the third embodiment, when the detected carrier is in the notch band, the level estimation value M of the detected carrier and the non-detected carrier in the notch band and the non-detected carrier in the vicinity of the notch band is It is determined by the detected value of the signal level of the nearest detected carrier adjacent above or below the notch band. For this reason, even when a detected carrier is located in the notch band, the detected value of the signal level outside the notch band is used for level estimation, and the non-detected carrier outside the notch band is detected by the detected value of the signal level in the notch band. Can be prevented from being estimated. As a result, transmission level control based on the detection result of the unbalanced component can be performed appropriately, and it is possible to eliminate the problem that the transmission level is controlled to be larger than the appropriate range.

  FIG. 15 is a diagram illustrating a fourth embodiment of operations in the level estimation unit 25 and the waveform generation unit 31. In the fourth embodiment, when level estimation of a non-detected carrier is performed, a level estimation value M is set using the detection values of the signal level in the latest high frequency and low frequency detection carriers adjacent to the non-detected carrier, For the detected carrier, the detected value of the signal level in the detected carrier is used as the level estimated value M as it is, and the transmission level of each carrier is controlled using these level estimated values M.

  In the fourth embodiment, there are notch bands for three carriers in the transmission carrier as shown in FIG. 15A, and measured values of the unbalanced components corresponding to each transmission carrier as shown in FIG. 15B. Is obtained. At this time, the detected value of the signal level by the FFT processing in the FFT unit 24 is a value indicated by a vertical broken line in FIG. The level estimation unit 25 first determines whether or not the carrier is a detected carrier in order to perform level estimation processing from a low frequency to a high frequency on the frequency axis. Here, in the case of a non-detected carrier, the detected value of the signal level in the nearest adjacent high-frequency side detected carrier and low-frequency side detected carrier is used, and the larger of these detected values is used as the non-detected carrier. Is set as the estimated level value M. In the case of a detected carrier, the detected value of the signal level in the detected carrier is set as the level estimated value M. Note that the average value of the latest high frequency side and low frequency side detected carriers may be used as the level estimation value M of the non-detected carrier.

  When the above processing is repeated for all the carriers in order from a low frequency to a high frequency, the level estimation value of each carrier is shown by a black dot on the detected carrier and a thick line extending in the horizontal direction in FIG. The detection result output unit 26 stores the level estimation value of the unbalanced component obtained by the level estimation in association with information such as the frequency of each carrier, and outputs it as the detection result of the unbalanced component for all carriers.

  The waveform generator 31 controls the transmission level to increase by a predetermined amount when the value of the unbalanced component of each carrier exceeds the threshold A, and decreases the transmission level by a predetermined amount when the value is smaller than the threshold B. To control. In this case, the detection result of the unbalanced component is lower than the threshold B in the low frequency band (band corresponding to FFT number 1) and exceeds the threshold A in the high frequency band (band corresponding to FFT number 99). As shown in FIG. 15D, in the transmission carrier after transmission level control, the transmission level of the carrier in the low frequency band in which the unbalance component is detected to be small is raised, and the high frequency band in which the unbalance component is detected in a large amount The carrier transmission level is lowered. As a result, as shown in FIG. 15E, the transmission level for each carrier is adjusted so that the unbalanced component after transmission level control falls within the appropriate range.

  FIG. 16 is a flowchart illustrating a processing procedure according to the fourth embodiment of the operations in the level estimation unit 25 and the waveform generation unit 31. First, it is determined whether unbalanced component level estimation and transmission level control processing has been completed for all carriers (step S41). If not completed, the process proceeds to level estimation processing by the level estimation unit 25 subsequent to step S42. If it has been completed, this processing is terminated. In step S42, the level estimation unit 25 determines whether the carrier is a detected carrier. Here, when the carrier is a non-detection carrier (not a detection carrier), the detection values of the signal level in the adjacent detection carrier on the higher frequency side and the detection carrier on the lower frequency side that are adjacent are used, and these detection values are large. This value is set as the level estimation value M of the undetected carrier (step S43). If the carrier is a detected carrier, the detected value of the signal level in the detected carrier is set as the level estimated value M (step S44).

  The subsequent processing of steps S45 to S49 is the same as the processing of steps S13 to S17 shown in FIG. 10, and the waveform generation unit 31 determines the level estimation value M by determining the level estimation value M and the threshold A and threshold B. When the value exceeds the thresholds A and B, the transmission level is adjusted to increase or decrease, and is determined as the transmission level of the detected carrier and the non-detected carrier within the estimated range.

  In the processing example described above, the operation for determining the level estimation value M of each carrier from the low frequency to the high frequency is shown. On the contrary, the same processing is performed from the high frequency to the low frequency. May be.

  By performing the processing of the fourth embodiment, the level estimation value M of the non-detected carrier is determined by the detection value of the signal level in the nearest upper and lower detected carriers. For this reason, even when a notch band exists, it is possible to prevent inappropriate level estimation of a non-detected carrier from being performed only by the detected value of the signal level of the notch band. As a result, transmission level control based on the detection result of the unbalanced component can be performed appropriately, and it is possible to eliminate the problem that the transmission level is controlled to be larger than the appropriate range.

  In the fourth embodiment, it is not necessary to use notch band information, and means for storing notch information can be omitted. Further, it is possible to estimate the level of the unbalanced component of each carrier and control the transmission level without depending on the width of the notch band, and it is possible to cope with the case where the notch band is variable. Further, finer transmission level control can be performed. However, when there is only a non-detected carrier in the band sandwiched between the detected carriers in the notch band, in this fourth embodiment, the transmission level of the corresponding non-detected carrier is controlled to be larger than the appropriate value. In the case where such a notch band is not set, the fourth embodiment can be applied. In addition, the process of the other 1st-3rd embodiment can be used in the part by which the above states are assumed, and the process of 4th Embodiment can also be used in another part.

  As described above, according to the present embodiment, the detection value of the signal level of the detected carrier in the notch band is not used for the level estimation of the unbalanced component of the non-detected carrier, thereby estimating the level of the unbalanced component. It is possible to prevent the value from becoming a low value corresponding to a state where no carrier is transmitted, and an appropriate level estimation value can be obtained. This makes it possible to appropriately control the transmission level of each carrier in multicarrier communication.

  The present invention prevents erroneous detection of an unbalanced component of a carrier around the notch band when there is a notch band that does not transmit a predetermined carrier when analyzing the frequency characteristics of the unbalanced component in a transmission path for multicarrier communication. This is useful for a signal level adjusting device and a signal level adjusting method for analyzing the frequency characteristics of the unbalanced component, a multi-carrier communication type communication device, and the like.

The block diagram which shows the structure of the communication apparatus which concerns on embodiment of this invention. Diagram showing examples of transmit signal waveform and common mode current waveform Diagram showing detection points for detecting unbalanced components and interpolation points for interpolating detection results The figure which shows the operation | movement which takes out only the component of an even-numbered harmonic while reducing the number of points of FFT by addition processing in this embodiment. The figure which shows an example of the FFT pre-processing part in this embodiment The figure which shows the specific example of the transmission carrier which has a notch band The figure which shows the specific example of the detection result of the unbalanced component by FFT The figure explaining the malfunction in the operation | movement of the level estimation in a level estimation part, and the transmission level control in a waveform generation part The figure which shows 1st Embodiment of the operation | movement in the level estimation part and waveform generation part of this embodiment. The flowchart which shows the process sequence of 1st Embodiment of the operation | movement in the level estimation part and waveform generation part of this embodiment. The figure which shows 2nd Embodiment of operation | movement in the level estimation part and waveform generation part of this embodiment. The flowchart which shows the process sequence of 2nd Embodiment of the operation | movement in the level estimation part and waveform generation part of this embodiment. The figure which shows 3rd Embodiment of the operation | movement in the level estimation part and waveform generation part of this embodiment. The flowchart which shows the process sequence of 3rd Embodiment of the operation | movement in the level estimation part and waveform generation part of this embodiment. The figure which shows 4th Embodiment of the operation | movement in the level estimation part and waveform generation part of this embodiment. The flowchart which shows the process sequence of 4th Embodiment of the operation | movement in the level estimation part and waveform generation part of this embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Communication apparatus 2 Unbalance component analysis part 3 Transmission part 4 Reception part 5 Coupling transformer 10 Power line 21 Unbalance component detection part 22 A / D conversion part 23 FFT pre-processing part 24 FFT part 25 Level estimation part 26 Detection result output part 31 Waveform generation unit 32 Amplification unit 33 Notch information storage unit

Claims (11)

A signal level adjusting device that adjusts the signal level of a multicarrier communication signal composed of a plurality of carriers according to an unbalanced component in a transmission path,
A time-frequency conversion unit for calculating a signal level on the frequency axis of the unbalanced component by time-frequency conversion;
A signal level estimation unit that estimates a signal level of an unbalanced component that is not calculated by the time-frequency conversion unit using a signal level of the unbalanced component calculated by the time-frequency conversion unit;
A waveform generation unit that generates the multicarrier communication signal based on the signal level of the unbalanced component estimated by the signal level estimation unit;
The signal level estimation unit uses the signal level of the unbalanced component calculated by the time-frequency conversion unit to estimate the signal level of the unbalanced component outside the notch band that does not transmit a predetermined carrier. Adjustment device. The signal level adjusting device according to claim 1,
When the detected carrier, which is a carrier for which the signal level of the unbalanced component has been calculated by the time-frequency converter, is located in the notch band, the signal level estimation unit is outside the notch band adjacent to or near the notch band. A signal level adjusting apparatus that estimates a signal level of an undetected carrier that is a carrier for which an unbalanced component signal level is not calculated by the time-frequency conversion unit using a signal level of a certain detected carrier. The signal level adjusting device according to claim 2,
The signal level estimator uses N detected carriers (N is an integer of 1 or more) and a (a is an integer of 1 or more) adjacent detection carriers, and calculates these detected carriers. A maximum value or an average value of the detected signal level is obtained, and this value is determined based on the N detection carriers, a non-detection carrier between the N detection carriers, and a non-detection adjacent to the a detection carrier side. A signal level adjusting device for estimating the carrier level. The signal level adjusting device according to claim 2,
The signal level estimation unit obtains a maximum value or an average value of signal levels calculated by N detection carriers (N is an integer of 1 or more) that is wider than the width of the notch band, and obtains this value as the value A signal level adjustment apparatus that uses N detected carriers and a level estimation value of non-detected carriers among the N detected carriers. The signal level adjusting device according to claim 2,
The signal level estimator uses a signal level calculated for a non-detected carrier in the vicinity of the notch band and a detected carrier of the latest high frequency or low frequency outside the notch band, and uses this value for the non-detected carrier. A signal level adjustment device for level estimation. The signal level adjusting device according to claim 2,
In the non-detected carrier, the signal level estimation unit sets a maximum value or an average value of the signal levels calculated by using the detected high-frequency and low-frequency detected carriers nearest to the non-detected carrier as a level estimated value. Is a signal level adjustment device using the signal level calculated by the detected carrier as it is as a level estimation value. The signal level adjusting device according to any one of claims 1 to 6,
A preprocessing unit that inputs digital data of an unbalanced component detection signal in the transmission path and performs preprocessing for reducing the number of points when performing time-frequency conversion of the digital data from the number of carriers of the multicarrier communication signal With
The time-frequency conversion unit performs a time-frequency conversion on the unbalanced component digital data with the reduced number of points.   Communication comprising the signal level adjusting device according to any one of claims 1 to 7, and comprising a transmission unit that adjusts and outputs a transmission level for each carrier of the multicarrier communication signal by the signal level adjusting device. apparatus. A signal level adjustment method for adjusting a signal level of a multicarrier communication signal including a plurality of carriers according to an unbalanced component in a transmission path,
Calculating a signal level on the frequency axis of the unbalanced component by time-frequency conversion;
Estimating the signal level of the unbalanced component not calculated by the time-frequency conversion using the signal level of the unbalanced component calculated by the time-frequency conversion;
Generating the multi-carrier communication signal based on the signal level of the estimated unbalanced component;
In the step of estimating the signal level of the unbalanced component, the signal level of the unbalanced component outside the notch band in which a predetermined carrier is not transmitted using the signal level of the unbalanced component calculated by the time-frequency conversion. A signal level adjustment method for estimating. A multicarrier communication signal comprising a plurality of carriers includes a notch that does not transmit a predetermined carrier, and adjusts the signal level of the multicarrier signal according to an unbalanced component in a transmission path,
A time-frequency conversion unit that calculates a signal level of an unbalanced component on the frequency axis by time-frequency conversion for at least one of the first carrier and the second carrier among the plurality of carriers;
For the third carrier of the plurality of carriers, the signal level of the unbalanced component is used as the signal level of the unbalanced component of the first carrier or the second carrier calculated by the time-frequency converter. A signal level estimation unit for estimating
  A waveform generation unit that generates the multicarrier communication signal based on the signal level of the unbalanced component of the third carrier estimated by the signal level estimation unit;
The signal level estimation unit uses the signal level of the first carrier or the second carrier when the first carrier and the second carrier are included in a band not having a notch. If the signal level of the third carrier is estimated and the first carrier is not transmitted by being included in a band having a notch and the second carrier is included in a band not having a notch, A signal level adjusting apparatus that estimates the signal level of the third carrier using the signal level of the second carrier. The signal level adjusting device according to claim 10, wherein the second carrier in the band not having a notch is adjacent to or in the vicinity of the band having a notch.

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