JP2010136254A - Digital signal transmitting apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a transmission apparatus which modulates a digital signal, using a predetermined modulation system for transmitting the digital signal toward a receiving apparatus via a predetermined transmission line. <P>SOLUTION: This transmission apparatus includes: a pseudo-atellite relay 6 having characteristics obtained by approximating characteristics of a relay on a transmission line; a vector arithmetic operation section 30 which obtains, as an error vector, deviation of a signal point, after passing through the satellite relay, from an ideal IQ signal point after mapping from a signal point of a digital signal transmitted via the pseudo satellite relay 6, and converts the signal point, after mapping of this signal point into a signal point corrected with the error vector; a delay section 7 for performing timing adjustment for correcting the signal point after mapping of this signal point with the error vector; and a quadrature modulation section 14 for performing quadrature modulation at the signal point corrected with the error vector. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a digital signal transmission apparatus that reduces the deterioration of required C / N due to a transmission path by performing distortion correction of signal points on the transmission path for each symbol and performing modulation.

  Of digital broadcasting of various standards currently in operation, using satellite broadcasting as an example, multiple broadcasters can transmit independent TS (transport stream) using a satellite repeater provided in the broadcasting satellite. Are multiplexed. Standards adopted in satellite digital broadcasting include ISDB-S and DVB-S2. Therefore, hereinafter, a description will be given of a generalized transmission apparatus that conforms to these standards.

  FIG. 1 is a block diagram showing a configuration of a transmission system via a satellite repeater provided in a broadcasting satellite. A main signal obtained by multiplexing video / audio / data broadcasting and the like is transmitted to the real satellite 2 by a digital modulation method specified by control information such as a TMCC signal from the transmission device 1. The satellite repeater of the actual satellite 2 includes an input multiplexer (IMUX) filter 21 which is an input filter placed in front of an amplifier, a traveling wave tube amplifier (TWTA) 22, and an output multiplexer (OMUX) which is an output filter after the amplifier. ) Filter 23 and the like, band extraction is performed for each channel from the broadcast wave signal received by the IMUX filter 21, gain control is performed by the traveling wave tube amplifier (TWTA) 22, unnecessary in the OMUX filter 23 Frequency components are suppressed, broadcast wave signals for all channels are synthesized by a subsequent synthesizer (not shown), and broadcast waves are directed toward receiving devices 3-1 to 3-N (N is a natural number of 1 or more). Send a signal.

  Even if various transmission controls are performed in the transmission device 1, the reception devices 3-1 to 3-N constantly monitor control information such as a TMCC signal transmitted together with the multiplexed broadcast wave signal. It is possible to switch the reception method and the like following.

  FIG. 2 is a block diagram showing only the configuration of the modulator 11 of the conventional transmission apparatus 1. The modulator 11 of the transmission apparatus 1 converts a serial bit string into parallel with respect to a data signal to be transmitted (hereinafter also simply referred to as a digital signal) to which predetermined encoding is applied and control information such as a TMCC signal is added. A serial / parallel conversion (S / P) unit 12 that performs mapping, a mapping unit 13 that performs mapping for each predetermined modulation method, and an orthogonal modulation unit 14 that performs orthogonal modulation according to each predetermined modulation method.

  The signal point coordinates mapped to the signal points corresponding to the digital modulation method specified by the control information such as the TMCC signal by the mapping unit 13 are input to the quadrature modulation unit 14, and the quadrature modulation unit 14 converts the signal point coordinates into the signal point coordinates. Quadrature modulation is performed to generate a modulated wave signal. The modulated wave signal generated by the quadrature modulation unit 14 is uplinked toward the real satellite 2.

  The predetermined digital modulation scheme includes BPSK including π / 2 shift BPSK, QPSK including π / 4 shift QPSK, 8PSK, 16APSK, 32APSK, and the like. The mapping unit 13 is a mapper corresponding to these modulation schemes. Can be prepared.

  The function of the satellite repeater in the real satellite 2 shown in FIG. 1 will be further described. The IMUX filter 21 is a band-pass filter corresponding to each channel frequency, and can extract only a band component for one channel from the received broadcast wave signal. The traveling wave tube amplifier (TWTA) 22 can further amplify the power of the extracted broadcast wave signal for one channel. The OMUX filter 23 is a band pass filter corresponding to each channel frequency, and extracts only the band component for one channel from the broadcast wave signal amplified by the traveling wave tube amplifier (TWTA) 22 and suppresses unnecessary frequency components. can do.

  On the other hand, it is desirable that the traveling wave tube amplifier (TWTA) 22 performs power amplification processing so that the relationship between the input level and the output level is proportional. However, this input / output characteristic actually shows non-linearity in which the gain decreases as the input level increases, and at the same time, the phase of the output signal relative to the input signal also rotates. Accordingly, when the input level is gradually increased, the output level is increased up to a certain level, but when the input level is exceeded, the output level is decreased. The operating point immediately before such a decrease in output level is generally called the output saturation point. Further, the case where the input level is lowered by X [dB] from the output saturation point is called “input back-off X [dB]”. Similarly, the input level is narrowed and the output level is lowered by Y [dB]. The operation in the state is referred to as “output backoff Y [dB]”.

  Since the most efficient transmission is possible at the saturation point of the traveling wave tube amplifier (TWTA) 22, when using PSK modulation such as BPSK including π / 2 shift BPSK, QPSK including π / 4 shift QPSK, and 8PSK, The input signal of the traveling wave tube amplifier (TWTA) 22 is automatically adjusted by a preattenuator or the like so as to be input at a level such that the input back-off becomes 0 dB. On the other hand, in the case of APSK modulation such as 16APSK and 32APSK, since there are signal points having a plurality of amplitudes in the signal point arrangement, the required C / N is likely to deteriorate due to the nonlinear characteristics of the amplifier. For this reason, when these modulation methods are used, the input back-off for the input signal of the traveling wave tube amplifier (TWTA) 22 depends on the output back-off for each combination of the modulation method and the error correction code. It is automatically adjusted by a pre-attenuator or the like so that the power loss and the required C / N deterioration due to nonlinearity are input at a level that minimizes the sum.

  As described above, a modulator used in a conventional digital signal transmission apparatus has a signal point corresponding to a symbol for each information bit number that can be transmitted simultaneously in one symbol according to a modulation method. The carrier wave is modulated by the transmission signal points mapped so as to be fixed. In particular, multi-level amplitude phase modulation such as 32APSK requires more linearity with respect to signal distortion, and in broadcasting satellite, in order to operate the traveling wave tube amplifier (TWTA) 22 to some extent linear, a larger output back-off is required. (For example, refer to Patent Document 1).

  On the other hand, ISDB-T, DVB-T, DVB-T2 and the like are standards adopted in terrestrial digital broadcasting.

  In these standards, a multiplexing method called OFDM (Orthogonal Frequency Division Multiplexing) is adopted. In OFDM, modulated waves such as 64QAM, which is a kind of QPSK and APSK, are multiplexed and transmitted on thousands of equally spaced carriers (see, for example, Non-Patent Document 1).

  FIG. 7 is a block diagram showing a configuration of a transmission apparatus using OFDM. The modulator 11 of the transmission apparatus 1 includes a serial / parallel conversion (S / P) unit 12 that converts a serial bit string into parallel with respect to a digital signal, a mapping unit 13 that maps each predetermined modulation method, 2 is the same as the transmission apparatus shown in FIG. 2 in that it includes an orthogonal modulation unit 14 that performs orthogonal modulation in accordance with each predetermined modulation method, but serial / parallel conversion (S / P) units 151a and 151b, and inverse high speed. The difference is that an OFDM conversion unit 15 including a Fourier transform (IFFT) unit 152 and parallel / serial conversion (P / S) units 153a and 153b is provided.

  Normally, a pilot signal, a transmission control signal, and a guard interval (not shown) are inserted in this block diagram, but they are omitted here because they do not affect the following description.

  In FIG. 7, as a function of a general transmission device that radiates radio waves by power amplification, an amplifier 16 including a filter 161, a power amplification unit 162, and a filter 163 in the output stage, and an antenna 17 are also shown. is there.

  Signal point coordinates mapped by a modulation method corresponding to a digital modulation method designated by control information such as a TMCC signal by a mapping unit 13 are converted into a number of OFDM by serial / parallel conversion (S / P) units 151a and 151b. Allocated to carrier wave. Next, an inverse fast Fourier transform (IFFT) unit 152 converts a large number of OFDM carriers into the same number of time axis signals. Furthermore, the parallel / serial conversion (P / S) units 153a and 153b convert the obtained time axis signal into one time series signal. Thereafter, the signal is input to the quadrature modulation unit 14, and the quadrature modulation unit 14 performs quadrature modulation on the signal to generate a modulated wave signal. The modulated wave signal generated by the quadrature modulation unit 14 further suppresses an unnecessary frequency component by the filter 161, amplifies it to a predetermined power by the power amplification unit 162, suppresses the unnecessary frequency component by the filter 163, and Radio waves are emitted toward a receiver (not shown).

  The predetermined digital modulation scheme includes BPSK including π / 2 shift BPSK, QPSK including π / 4 shift QPSK, 8PSK, 16QAM, 32QAM, 64QAM, 128QAM, or 256QAM which is a kind of APSK. The mapping unit 13 can prepare a mapper corresponding to these modulation methods.

  Since a modulated wave that has been multiplexed by OFDM has a very high peak power with respect to the average power, this power amplifier is required to have extremely high linearity and is operated with a large back-off (for example, Non-Patent Document 2). reference).

Japanese Patent Publication No. 2008-199574 Japan Broadcasting Corporation, NHK Digital Television Technical Textbook, published by Japan Broadcasting Corporation, February 20, 2007, p.112 Transistor Technology March 2008 Special Issue, “RF World No. 1”, CQ Publishing, published March 1, 2008, p. 55

  In a conventional modulator, after passing through a satellite repeater, the signal point arrangement on the receiver side is shifted from the desired point due to nonlinear distortion of the traveling wave tube amplifier (TWTA), even if the signal bit arrangement is the same information bit. And spread on the orthogonal IQ plane. For this reason, in particular, in multi-value amplitude phase modulation, errors are likely to occur due to intersymbol interference, resulting in an increase in required C / N and deterioration in transmission quality. Further, in the case of multi-level amplitude phase modulation, the output power of the traveling wave tube amplifier (TWTA) is taken off, while the reception power is reduced, resulting in the required C / N degradation. In addition, since terrestrial digital broadcasting also employs OFDM, the amplifier needs to be operated with a large back-off.

  In view of the above problems, the object of the present invention is to reduce the required C / N degradation amount and output back-off amount as much as possible by correcting nonlinear distortion caused by a satellite repeater or the like in advance on the modulator side of the transmission apparatus. Another object of the present invention is to provide a digital signal transmitting apparatus that reduces the deviation of signal point arrangement on the receiving apparatus side.

  According to the present invention, when transmitting a multi-level modulation signal, an error vector between an ideal signal point arrangement (hereinafter referred to as an ideal IQ signal point) and an IQ signal point after passing through an assumed transmission path is symbol by symbol. By calculating and converting the signal vector into a signal point obtained by subtracting the error vector, the spread of the symbol points due to passage through the transmission path is reduced on the IQ plane, and the required C / N deterioration is improved.

That is, a transmitting apparatus according to the present invention is a transmitting apparatus that modulates a digital signal with a predetermined modulation method in order to transmit a digital signal to a receiving apparatus via a predetermined transmission path, A pseudo transmitter having characteristics corresponding to the characteristics of the target device, and a deviation of a signal point after passing the target device from a signal point of a digital signal transmitted through the pseudo transmitter with respect to an ideal IQ signal point after mapping Vector calculation means for obtaining an error vector and converting the signal point after mapping of the signal point to a signal point corrected with the error vector, and timing for correcting the signal point after mapping of the signal point with the error vector Timing adjusting means for adjusting, quadrature modulation means for performing quadrature modulation at the signal point corrected by the error vector,
It is characterized by providing.

  The transmitting device according to the present invention is a transmitting device that modulates a digital signal with a predetermined modulation scheme in order to transmit the digital signal to the receiving device via the predetermined transmission path, A pseudo transmitter having characteristics corresponding to the characteristics of the target device, and a signal point deviation after passing the target device with respect to an ideal IQ signal point after mapping from a signal point of a digital signal transmitted through the pseudo transmitter is an error. Vector calculation means for obtaining a signal point after mapping of the signal point as a vector and converting the signal point to a signal point corrected with the error vector, and timing adjustment for correcting the signal point after mapping of the signal point with the error vector The timing adjusting means as a set of signal point converters includes a plurality of signal point converters arranged in series and a plurality of signal point converters arranged in series. , Characterized in that it comprises a quadrature modulating means for quadrature modulating a signal point after mapping of the signal point at the signal point is corrected in the error vector.

  In addition, the transmission device according to the present invention is a transmission device that modulates the digital signal with a predetermined modulation scheme and performs OFDM multiplexing to transmit the digital signal to the reception device via a predetermined transmission path. An OFDM converter that converts the frequency axis signal point sequence into a time axis OFDM signal, a pseudo transmitter having characteristics corresponding to the characteristics of the target device on the transmission path, and the time axis signal point sequence as a frequency axis OFDM signal. An OFDM inverse conversion unit for conversion, and a signal point deviation after passing through the target device with respect to an ideal IQ signal point after mapping from a signal point of a digital signal transmitted via the pseudo-transmitter is obtained as an error vector, Vector calculation means for converting the signal point after mapping of the point into a signal point corrected by the error vector, and the signal point after mapping of the signal point is converted into the error vector. Timing adjusting means for adjusting the timing for correction at the time, an OFDM converter for converting the signal point corrected by the error vector into a time-axis OFDM signal, and orthogonal modulation means for performing orthogonal modulation with the time-axis OFDM signal It is characterized by.

  In addition, the transmission device according to the present invention is a transmission device that modulates the digital signal with a predetermined modulation scheme and performs OFDM multiplexing to transmit the digital signal to the reception device via a predetermined transmission path. An OFDM converter that converts the frequency axis signal point sequence into a time axis OFDM signal, a pseudo transmitter having characteristics corresponding to the characteristics of the target device on the transmission path, and converts the time axis signal point sequence into a frequency axis OFDM signal. OFDM inverse transform unit, obtains, as an error vector, a deviation of a signal point after passing through the target device with respect to an ideal IQ signal point after mapping from a signal point of a digital signal transmitted through the pseudo transmitter, and mapping of the signal point Vector calculation means for converting a later signal point into a signal point corrected with the error vector, and a signal point after mapping of the signal point with the error vector The timing adjustment means for adjusting the timing to correct is set as a set of signal point converters, and a plurality of signal point converters arranged in series and the plurality of signal point converters arranged in series after the mapping of the signal points. An OFDM conversion unit that converts a signal point obtained by correcting the signal point with the error vector into a time-axis OFDM signal, and orthogonal modulation means that orthogonally modulates the time-axis OFDM signal are provided.

  In the transmission apparatus according to the present invention, the predetermined modulation scheme includes ASK, PSK, or APSK. Since QAM is one in which the signal point arrangement is selected on an orthogonal lattice in APSK modulation, QAM is also included in APSK.

  A transmitting apparatus according to the present invention is a transmitting apparatus that transmits a digital signal by VSB modulation using a predetermined modulation method in order to transmit a digital signal to a receiving apparatus via a predetermined transmission path. A VSB filter unit that performs predetermined band limitation, a pseudo transmitter having characteristics corresponding to the characteristics of the target device on the transmission path, a VSB detection unit that performs VSB detection, and a digital signal transmitted via the pseudo transmitter A deviation of the signal point after passing through the target device from the ideal IQ signal point after mapping from the signal point is obtained as an error vector, and the signal point after mapping the signal point is converted to a signal point corrected with the error vector. Vector calculation means; timing adjustment means for adjusting timing for correcting the signal points after mapping of the signal points with the error vectors; and the error vectors. A VSB filter unit for performing a predetermined band limiting on the corrected signal point sequence Le, characterized in that it comprises a quadrature modulating means for quadrature modulating the output of the VSB filter unit.

  A transmitting apparatus according to the present invention is a transmitting apparatus that transmits a digital signal by VSB modulation using a predetermined modulation method in order to transmit a digital signal to a receiving apparatus via a predetermined transmission path. A VSB filter unit that performs a predetermined band limitation, a pseudo transmitter having characteristics corresponding to the characteristics of the target device on the transmission path, a VSB detection unit that performs VSB detection, and a signal point of a digital signal transmitted via the pseudo transmitter To calculate a deviation of the signal point after passing through the target device from the ideal IQ signal point after mapping as an error vector, and convert the signal point after mapping of the signal point to a signal point corrected by the error vector And a set of signal point converters for adjusting timing in order to correct the signal point after mapping of the signal point with the error vector Then, a predetermined band limitation is applied to a signal point sequence in which signal points after mapping of the signal points are corrected by the error vector by the plurality of signal point converters arranged in series and the plurality of signal point converters arranged in series. And a VSB filter unit for performing orthogonal modulation, and orthogonal modulation means for performing orthogonal modulation on the output of the VSB filter unit.

  In the transmission apparatus according to the present invention, the predetermined modulation scheme is a modulation scheme in which signal points are arranged one-dimensionally.

  In the transmitter according to the present invention, the pseudo transmitter has a set value that approximates characteristics of a predetermined input filter, amplifier, and output filter in the target device. When no amplifier is present in the repeater, both the input filter and the output filter mean simple band-pass filters.

  Further, in the transmission device according to the present invention, the target device includes a repeater, an electrical device, an optical device, or a combination thereof having one or more known characteristics among the frequency characteristics and nonlinear characteristics of phase and amplitude. It is characterized by.

  According to the present invention, since the expected transmission path distortion is calculated in advance on the transmission side and corrected for each symbol, a large required C / C is required particularly in the case of multilevel amplitude phase modulation that is weak against the influence of nonlinear distortion. There exists an effect which improves deterioration of N.

  First, the transmission apparatus according to the first embodiment of the present invention will be described. In each drawing, the same reference numerals will be given to the same components.

Example 1
FIG. 3 is a block diagram showing only the configuration of the modulator in the transmission apparatus according to the first embodiment of the present invention (as described above, a generalized transmission apparatus compliant with various standards). The transmission apparatus 1 according to the first embodiment is a transmission apparatus applicable to the transmission system via the satellite repeater provided in the broadcast satellite shown in FIG. 1, and transmits a broadcast wave signal to the existing broadcast satellite. Can do. Further, it can be incorporated into a transmission system independently of another existing transmission apparatus. Therefore, the transmission apparatus 1 according to the first embodiment can be compliant with standards adopted in digital broadcasting, such as ISDB-S, DVB-S2, and the like. Therefore, in order to transmit the digital signal to the receiving device 3-N via the satellite repeater of the real satellite 2, the transmitting device 1 according to the first embodiment modulates the digital signal with a predetermined modulation method. Configured as

  As shown in FIG. 3, the modulator in the transmission apparatus 1 of the first embodiment uses a serial / serial signal that converts a serial bit string into parallel with respect to a digital signal to be transmitted (a signal before modulation subjected to predetermined encoding). A parallel conversion (S / P) unit 12, a mapping unit 13 that maps for each predetermined modulation method, a signal point conversion unit 5, and an orthogonal modulation unit 14 that performs orthogonal modulation in accordance with each predetermined modulation method Prepare. Here, the serial / parallel conversion (S / P) unit 12, the mapping unit 13, and the quadrature modulation unit 14 function in the same manner as the conventional general transmission apparatus shown in FIG.

  The signal point conversion unit 5 includes a pseudo satellite repeater 6, a delay unit 7, and a vector calculation unit 30 including a first vector addition unit 8 and a second vector addition unit 9.

  The pseudo-satellite repeater 6 has characteristics approximating the frequency characteristics and nonlinear characteristics of the phase and amplitude of the satellite repeater of the real satellite 2 shown in FIG. 1, that is, an input multiplexer (IMUX) filter 61, a traveling wave tube amplifier ( TWTA) 62 and an output multiplexer (OMUX) filter 63. The IMUX filter 61 performs band extraction for each channel from the digital signal input through the mapping unit 13, and a traveling wave tube amplifier (TWTA). The gain is controlled by 62 and unnecessary frequency components are suppressed by the OMUX filter 63. Thereby, the pseudo satellite repeater 6 simulates a signal point IQ that can be generated by the satellite repeater of the real satellite 2 with respect to the ideal IQ signal point after mapping the signal point of the digital signal to be transmitted. Send a signal.

  The first vector adder 8 generates, for each symbol, a signal point shift from the ideal IQ signal point after mapping of the signal point of the digital signal to be transmitted, which is transmitted from the pseudo satellite repeater 6, as an error vector.

  The delay unit 7 adjusts timing in order to correct the signal point after mapping of the signal point by the mapping unit 13 with the error vector by the first vector addition unit 8. Therefore, the delay unit 7 functions to adjust timing with the same delay amount as the delay amount D generated by the pseudo satellite repeater 6.

  The second vector addition unit 9 converts the signal point after mapping of the signal point by the mapping unit 13 into a signal point corrected by the error vector by the first vector addition unit 8. The first vector adder 8 and the second vector adder 9 constitute a vector calculator 30 and function as a vector calculator.

  The quadrature modulation unit 14 performs quadrature modulation in accordance with a predetermined modulation method at the signal point corrected with the error vector by the second vector addition unit 9. The predetermined modulation scheme includes BPSK including π / 2 shift BPSK, QPSK including π / 4 shift QPSK, 8PSK, 16APSK, or 32APSK.

  Hereinafter, the operation of the transmission apparatus according to the first embodiment will be described in more detail.

  The digital signal input to the modulator in the transmitter 1 of the first embodiment is serial / parallel converted into the number of bits that can be transmitted per symbol by the serial / parallel conversion (S / P) unit 12 using the modulation method used for transmission. The The mapping unit 13 performs a mapping process for converting the converted signal into an I signal amplitude and a Q signal amplitude.

  Next, the mapped signal is divided into two, one of which is an input multiplexer (IMUX) filter 61 and traveling wave tube amplifier (TWTA) in the pseudo satellite repeater 6 simulating the characteristics of the satellite repeater of the real satellite 2. ) 62 and an output multiplexer (OMUX) filter 63. Here, the amplitude characteristic and the group delay characteristic with respect to the frequency of the IMUX filter 61 and the OMUX filter 63 in the pseudo satellite repeater 6 and the AM-AM characteristic and AM-PM characteristic of the TWTA are the characteristics of the satellite repeater of the real satellite 2. It is set to an approximate characteristic, and is preferably set to a value at the time of designing the actual satellite 2 or equivalent to a set value during operation of the satellite repeater of the actual satellite 2.

  Further, since the pseudo satellite repeater 6 may simulate the characteristics of the satellite repeater of the real satellite 2, it is not strictly required to be identical to the characteristics of the satellite repeater of the real satellite 2. Not too long. Therefore, as long as it has the same function as the input multiplexer (IMUX) filter 61, traveling wave tube amplifier (TWTA) 62, and output multiplexer (OMUX) filter 63, it can be configured in any manner. For example, the traveling wave tube amplifier Instead of (TWTA) 62, it may be configured by a memory storing a lookup table for amplifying and converting a corresponding digital value signal. Further, the input multiplexer (IMUX) filter 61 and the output multiplexer (OMUX) filter 63 can also be constituted by digital filters.

  Next, assuming that the delay amount D caused by the passage through the pseudo satellite repeater 6 is given by the delay unit 7 to the other signal of the two distributions in the mapped signal, the same delay amount D is used for vector calculation for each symbol. Try to synchronize.

  Next, the first vector addition unit 8 first derives, for each symbol, the deviation of the signal point after passing through the pseudo satellite repeater 6 as seen from the ideal IQ signal point after the mapping as an error vector. The calculation for obtaining the error vector is performed so that the average power of the signal points input from the pseudo satellite repeater 6 is equal to the average power of the IQ signal points input from the delay unit 7, or more preferably, the vector adder After adjusting so that the average power of the output of 8 is minimized, the IQ signal point vector input from the delay unit 7 is subtracted from the signal point vector input from the pseudo satellite repeater 6. Next, a signal point obtained by subtracting the error vector is generated by the second vector adder 9 (see FIG. 4). The second vector adder 9 is set so that the average power of the converted IQ signal point is equal to the average power of the original ideal IQ signal point so as not to affect the subsequent processing of the quadrature modulation unit 14 and the subsequent. After the conversion, the amplitude of all symbols is adjusted by a constant and output.

  The quadrature modulation unit 14 performs quadrature modulation using these vector-calculated signal points. In this case, the vector calculation unit 30 is composed of the first vector addition unit 8 and the second vector addition unit 9, but the calculation performed by these two times the vector of the output signal point of the delay unit 7, It is also realized by adjusting the output vector of the repeater 6 so that the average power of the signal point input from the pseudo satellite repeater 6 becomes equal to the average power of the IQ signal point input from the delay unit 7 and then subtracting it. it can.

  Therefore, according to the transmission apparatus 1 of the first embodiment, it is possible to transmit a broadcast wave signal with improved required C / N degradation.

  Next, a transmission apparatus according to the second embodiment of the present invention will be described. In each drawing, the same reference numerals will be given to the same components.

(Example 2)
FIG. 5 is a block diagram showing only the configuration of the modulator in the transmission apparatus according to the second embodiment of the present invention.

  The transmission apparatus 1 according to the second embodiment is an apparatus configured to further improve error correction accuracy in the transmission apparatus according to the first embodiment described above. That is, the pseudo satellite repeater 6, the vector calculation unit 30 functioning as a vector calculation unit, and the delay unit 7 functioning as a timing adjustment unit in the transmission apparatus of the first embodiment are arranged in series as a set of signal point converters. The quadrature modulation unit 14 includes a signal point converter at the final stage in which signal points after mapping of signal points by the mapping unit 13 are arranged in series by a plurality of signal point converters arranged in series. Quadrature modulation is performed at the signal point corrected by the error vector obtained through the above process.

  In the transmission apparatus 1 of the second embodiment, a set of signal point converters 1-n (n is a natural number of 1 or more) function in the same manner. In FIG. Input multiplexer (IMUX) filters 61-1, 61-2, 61-3, traveling wave tube amplifiers (TWTA) 62-1, 62-2, 62-3, and output multiplexer (OMUX) filters 63-1, 63 -2, 63-3, vector operation units 30-1, 30-2, 30-3, first vector addition units 8-1, 8-2, 8-3, delay units 7-1, 7- 2, 7-2 a, 7-2 b, 7-3, 7-3 a, 7-3 b, and 7-3 c and second vector adders 9-1, 9-2, and 9-3, respectively. Input multiplexer (IMUX) filter 61 and traveling wave tube amplification in the transmitter of Example 1 Has a (TWTA) 62, an output multiplexer (OMUX) filter 63, a vector operation unit 30, a first vector addition unit 8, a delay unit 7, a function corresponding to the second vector adding unit 9.

  In FIG. 5, the signals input to the subtraction “−” of the vector addition 8-2 and the vector addition 8-3 use 2 and 3 delay units from the output of the mapping 13, respectively. If the output is −1, the configuration up to the subtraction “−” of the vector addition 8-2 can reduce the delay D7-2a and the delay unit to one. Furthermore, if the connection of the subtraction “−” of the vector addition 8-3 is made the output of the delay D7-2a based on the above assumption, it is possible to reduce the delay unit to one.

  Therefore, according to the transmission apparatus 1 of the second embodiment, it is possible to transmit a broadcast wave signal in which the required C / N deterioration is further improved.

  An example of the result of the simulation calculation in the transmission apparatus 1 according to the first and second embodiments is typically shown in FIG. 6 for 32APSK modulation.

  Referring to FIG. 6, FIG. 6 (A) shows a mapping of ideal IQ signal points in A shown in FIG. Accordingly, it is desirable that the 32 APSK modulated signal point originally reaches the receiving device with this signal point arrangement.

  FIG. 6B shows an IQ signal after passing through the pseudo satellite repeater 6 in FIG. 5B shown in FIG. 5, which has an IQ signal point arrangement equivalent to that at the time of demodulation through the satellite repeater in the real satellite 2. Shows the mapping of points. This is because when the ideal IQ signal point is orthogonally modulated and passed through the satellite repeater, the band limitation by the input multiplexer (IMUX) filter, the nonlinear characteristic by the traveling wave tube amplifier (TWTA), the band by the output multiplexer (OMUX) filter This is because of the influence of the restriction, and it can be seen that when the existing satellite repeater is passed without correction, the equivalent reception C / N is greatly degraded. According to the simulation results, the error vector amplitude (EVM) at this time was 16.2%. Here, the output back-off (output ratio at the time of modulation wave output to saturation output at the time of no modulation in the output of the OMUX filter) was set to 3.0 dB.

  FIG. 6C shows mapping of IQ signal points represented by error vectors obtained by one vector operation in C shown in FIG.

  FIG. 6D shows an IQ equivalent to that obtained when demodulating the signal modulated by the IQ signal point corrected by one vector calculation in FIG. 5D shown in FIG. The mapping of the IQ signal point after passing through the pseudo satellite repeater 6 having the signal point arrangement is shown. It can be seen that the degradation of equivalent C / N is improved as compared with FIG. According to the result of the simulation, the EVM could be suppressed to 6.9%.

  FIG. 6E shows the mapping of IQ signal points represented by error vectors obtained by two vector operations in E shown in FIG.

  FIG. 6 (F) shows an IQ signal equivalent to that at the time of demodulation in which the signal modulated by the IQ signal point corrected with the twice error vector in F shown in FIG. 5 is passed through the satellite repeater in the real satellite 2. The mapping of the IQ signal point after passing through the pseudo satellite repeater 6 having the point arrangement is shown. Compared with FIG. 6D, it can be seen that the deterioration of the equivalent C / N is further improved. According to the result of simulation, EVM could be suppressed to 4.2%.

  Thus, it can be seen that a further decrease in EVM value and improvement in required C / N deterioration can be expected by a plurality of distortion correction calculations.

  Next, a transmission device according to a third embodiment of the present invention will be described. In each drawing, the same reference numerals will be given to the same components.

(Example 3)
FIG. 8 is a block diagram illustrating a configuration of the transmission apparatus according to the third embodiment of the present invention. The transmission apparatus 1 according to the third embodiment is a transmission apparatus applicable to the transmission system using OFDM shown in FIG. 7 described above, and can transmit a broadcast wave signal to an existing broadcast receiver. Further, it can be incorporated into a transmission system independently of another existing transmission apparatus. Therefore, the transmission apparatus 1 according to the third embodiment can be compliant with standards adopted in digital broadcasting, for example, ISDB-T, DVB-T, DVB-T2, and the like. Therefore, the transmission apparatus 1 according to the third embodiment is configured as a transmission apparatus that modulates the digital signal with a predetermined modulation method in order to transmit the digital signal to a reception apparatus (not illustrated).

  As illustrated in FIG. 8, the modulator 11 in the transmission device 1 according to the third embodiment converts a serial bit string into a serial signal in parallel with a digital signal to be transmitted (a signal before modulation subjected to predetermined encoding). / Parallel conversion (S / P) unit 12, mapping unit 13 for mapping for each predetermined modulation scheme, signal point conversion unit 5, OFDM conversion unit 15, and orthogonal modulation unit 14 for performing orthogonal modulation. Here, the serial / parallel conversion (S / P) unit 12, the mapping unit 13, the OFDM conversion unit 15, and the quadrature modulation unit 14 function in the same manner as in the conventional general transmission apparatus shown in FIG. To do.

  The signal point conversion unit 5 includes an OFDM conversion unit including serial / parallel conversion (S / P) units 181a and 181b, an inverse fast Fourier transform (IFFT) unit 182, and parallel / serial conversion (P / S) units 183a and 183b. 18, a pseudo-amplifier 19 including a filter unit 191, a power amplification unit 192, and a filter unit 193, serial / parallel conversion (S / P) units 201a and 201b, a fast Fourier transform (FFT) unit 202, and parallel / serial An OFDM inverse conversion unit 20 including conversion (P / S) units 203a and 203b, a delay unit 7, and a vector operation unit 30 including a first vector addition unit 8 and a second vector addition unit 9 are provided.

  The pseudo-amplifier 19 has characteristics approximate to the frequency characteristics and nonlinear characteristics of the phase and amplitude in the amplifier 16 shown in FIG. 7, that is, includes a filter 191, a power amplifier 192, and a filter 193. Unnecessary frequency components are suppressed, amplified to a predetermined power by the power amplifier 192, and unnecessary frequency components are suppressed by the filter 193.

  As a result, the pseudo-amplifier 19 is multiplexed with OFDM having a signal point that simulates a signal point shift that can be caused by the amplifier 16 with respect to the ideal IQ signal point after mapping the signal point of the digital signal to be transmitted. Send IQ signal of axis signal. Further, the OFDM inverse conversion unit 20 at the subsequent stage converts the IQ signal of the time axis signal multiplexed by OFDM output from the pseudo-amplifier 19 into an IQ signal of the frequency axis.

  The first vector addition unit 8 generates, for each symbol, a deviation from the signal point after mapping of the signal point of the digital signal to be transmitted, which is sent from the OFDM inverse conversion unit 20, from the ideal IQ signal point as an error vector.

  The delay unit 7 adjusts timing in order to correct the signal point after mapping of the signal point by the mapping unit 13 with the error vector by the first vector addition unit 8. Therefore, the delay unit 7 functions to adjust the timing with the same delay amount as the delay amount D generated by the OFDM conversion unit 18, the pseudo amplifier 19, and the OFDM inverse conversion unit 20.

  The second vector addition unit 9 converts the signal point after mapping of the signal point by the mapping unit 13 into a signal point corrected by the error vector by the first vector addition unit 8. The first vector adder 8 and the second vector adder 9 constitute a vector calculator 30 and function as a vector calculator.

  The OFDM conversion unit 15 assigns the output of the signal conversion unit 5 to a number of OFDM carriers by serial / parallel conversion (S / P) units 151a and 151b. Next, an inverse fast Fourier transform (IFFT) unit 152 converts a large number of OFDM carriers into the same number of time axis signals. Furthermore, the parallel / serial conversion (P / S) units 153a and 153b convert the obtained time axis signal into one time series signal. Thereafter, the signal is input to the quadrature modulation unit 14, and the quadrature modulation unit 14 performs quadrature modulation according to a predetermined modulation method at the signal point corrected by the error vector by the second vector addition unit 9. The predetermined modulation schemes here include BPSK including π / 2 shift BPSK, QPSK including π / 4 shift QPSK, 8PSK, 16QAM, 32QAM, 64QAM, 128QAM, and 256QAM.

  Hereinafter, the operation of the transmission apparatus according to the third embodiment will be described in more detail.

  The digital signal input to the modulator in the transmitter 1 of the third embodiment is serial / parallel converted to the number of bits that can be transmitted per symbol by the serial / parallel conversion (S / P) unit 12 using the modulation method used for transmission. The The mapping unit 13 performs a mapping process for converting the converted signal into an I signal amplitude and a Q signal amplitude.

  Next, the mapped signal is divided into two, and one of the signals is allocated to a number of OFDM carriers by the serial / parallel conversion (S / P) units 181a and 181b of the OFDM conversion unit 18. The inverse Fourier transform (IFFT) unit 182 converts OFDM carrier waves into the same number of time axis signals. This time axis signal is passed through the filter 191, the power amplifier 192, and the filter 193 in the pseudo-amplifier 19 that simulates the characteristics of the amplifier 16. Here, the amplitude characteristic and group delay characteristic with respect to the frequency of the filter 191 and the filter 193 in the pseudo amplifier 19 and the AM-AM characteristic and AM-PM characteristic of the power amplifier 192 are set to characteristics close to those of the amplifier 16, Preferably, it is set to a value at the time of designing the amplifier 16 or equivalent to a setting value during operation of the amplifier 16. The signal after passing through the pseudo repeater is distributed in the same number as the OFDM carrier by the serial / parallel conversion (S / P) units 201a and 201b of the OFDM inverse conversion unit 20, and is converted into a frequency axis signal by the fast Fourier transform (FFT) unit 202. Converted. Thereafter, the signal is converted into one signal series by parallel / serial conversion (P / S) units 203a and 203b. This signal sequence is a sequence of signal points affected by the pseudo-amplifier 19.

  Needless to say, the pseudo-amplifier 19 is not required to be strictly identical to the characteristics of the amplifier 16 because it may simulate the characteristics of the amplifier 16. Therefore, as long as the filter 161, the power amplification unit 162, and the filter 163 have the same functions, the filter 161, the power amplification unit 162, and the filter 163 can be configured in any manner. For example, instead of the power amplification unit 192, the corresponding digital value signal is amplified and converted. It can also be configured with a memory storing an uptable. In addition, the filter 191 and the filter 193 can be configured by digital filters.

  Assuming that the delay amount D caused by passing through the OFDM converter 18, the pseudo-amplifier 19, and the OFDM inverse converter 20 is given, the delay unit 7 gives the same delay amount D to the other signal of the two distributions in the mapped signal. Every time a vector operation is performed, synchronization is performed.

  In the vector calculation, the first vector adder 8 first calculates the deviation of the signal points after passing through the OFDM converter 18, the pseudo-amplifier 19, and the OFDM inverse converter 20 as viewed from the ideal IQ signal points after the mapping as an error vector for each symbol. To derive. The calculation for obtaining the error vector is performed so that the average power of the signal points input from the OFDM inverse transform unit 20 is equal to the average power of the IQ signal points input from the delay unit 7, or more preferably, the vector addition unit After adjusting so that the average power of the output of 8 is minimized, the IQ signal point vector input from the delay unit 7 is subtracted from the signal point vector input from the OFDM inverse transform unit 20.

  Next, a signal point obtained by subtracting the error vector is generated by the second vector adder 9 (see FIG. 4). Note that the second vector adder 9 makes the average power of the converted IQ signal point the same as the average power of the original ideal IQ signal point so as not to affect the subsequent processing of the OFDM conversion unit 15. After conversion, the amplitudes of all symbols are adjusted by a constant multiple and output. Thereafter, the signal points obtained by the vector calculation in the OFDM conversion unit 15 are converted into OFDM signals, and the orthogonal modulation unit 14 performs orthogonal modulation. Here, the vector calculation unit 30 is composed of the first vector addition unit 8 and the second vector addition unit 9, but the calculation performed by these two times the vector of the output signal point of the delay unit 7, the pseudo amplifier This can also be realized by adjusting the 19 output vectors so that the average power of signal points input from the OFDM inverse transform unit 20 becomes equal to the average power of IQ signal points input from the delay unit 7 and then subtracting them.

  As described above, according to the transmission device 1 of the third embodiment, in order to transmit a digital signal to the reception device via a predetermined transmission path, the digital signal is modulated by a predetermined modulation method and OFDM-multiplexed. The transmission apparatus is provided as a transmission apparatus, which includes an OFDM conversion unit 18 that converts a frequency-axis signal point sequence into a time-axis OFDM signal, and a pseudo-transmitter having a characteristic corresponding to the characteristic of a target device on a transmission path (this book). In the embodiment, a pseudo-amplifier 19), an OFDM inverse transform unit 20 that converts a time-axis signal point sequence into a frequency-axis OFDM signal, and an ideal IQ signal after mapping from signal points of a digital signal transmitted via a pseudo-transmitter The deviation of the signal point after passing through the target device with respect to the point is obtained as an error vector, and the signal point after mapping of the signal point is converted into a signal point corrected with the error vector. A Kottle calculation unit 30, a delay unit 7 that adjusts timing to correct the signal point after mapping of the signal point with an error vector, and an OFDM conversion unit 15 that converts the signal point corrected with the error vector into a time-axis OFDM signal And a quadrature modulation unit 14 that performs quadrature modulation using the time-axis OFDM signal, and can transmit a broadcast wave signal with improved degradation of required C / N.

  Further, as in the case of the expansion from the first embodiment to the second embodiment, the error correction accuracy in the transmission device can be further increased. That is, the transmission apparatus according to the third embodiment includes an OFDM conversion unit 18, a pseudo-amplifier 19, an OFDM inverse conversion unit 20, a vector calculation unit 30 that functions as a vector calculation unit, and a delay unit 7 that functions as a timing adjustment unit. The signal point converter includes a plurality of signal point converters 1-n arranged in series, and the OFDM conversion unit 15 uses the plurality of signal point converters arranged in series to perform signal point mapping after signal points are mapped by the mapping unit. The signal points corrected by the error vector obtained through the final stage signal point converter arranged in series are converted into OFDM signals, and the orthogonal modulation unit 14 is configured to orthogonally modulate the output of the OFDM conversion unit 15. It is also possible to do.

  More specifically, as a mode in which the transmission device 1 of the third embodiment is expanded, in order to transmit a digital signal to the reception device via a predetermined transmission path, the digital signal is modulated by a predetermined modulation method. It can be provided as a transmission apparatus that performs OFDM multiplexing transmission. This transmission apparatus includes an OFDM converter 18 that converts a frequency-axis signal point sequence into a time-axis OFDM signal, a pseudo-transmitter (in this embodiment, a pseudo-amplifier 19) having characteristics corresponding to the characteristics of a target device on the transmission path, OFDM inverse conversion unit 20 for converting a time axis signal point sequence to a frequency axis OFDM signal, and a signal point after passing through the target device with respect to an ideal IQ signal point after mapping from a signal point of a digital signal transmitted via the pseudo transmitter Is calculated as an error vector, and a vector calculation unit 30 that converts the signal point after mapping of the signal point to a signal point corrected with the error vector, and the signal point after mapping of the signal point is corrected with the error vector A plurality of signal point converters 1-n arranged in series, and a series arrangement A plurality of signal point converters convert the signal point after mapping of the signal point with the error vector, an OFDM conversion unit 15 that converts the signal point into a time-axis OFDM signal, and orthogonally modulates the time-axis OFDM signal It is also possible to employ a configuration that includes a quadrature modulation unit 14 and transmits a broadcast wave signal with improved required C / N degradation.

  In the above-described embodiment, the case where the present invention is applied to satellite digital broadcasting and terrestrial digital broadcasting that performs OFDM multiplexing has been described as a representative example. However, the present invention can also be applied to other transmission paths. For example, 16QAM modulation, 32QAM modulation, or the like is used as a modulation method for material transmission for transmitting a video signal from a shooting site to a studio via a communication satellite and / or a repeater. In this case, the mapping unit 13 in FIG. 3 according to the first embodiment or FIG. 5 according to the second embodiment corresponds to 16QAM or 32QAM modulation, and the characteristics of the pseudo satellite repeater or pseudo amplifier are set to the input multiplexer (IMUX) of the communication satellite. ) It may be configured to approximate the characteristics of the filter, traveling wave tube amplifier, and output multiplexer (OMUX) filter.

  Further, in the case where the digitally modulated signal is further subjected to electrical / optical conversion and transmitted through an optical fiber, and the optically / electrically converted signal is restored and digitally demodulated, an electrical / optical converter, Non-linear characteristics of the optical / electrical converter may be a problem. In such a case, in FIG. 3 or FIG. 5, instead of configuring the pseudo satellite repeater 6 with an input multiplexer (IMUX) filter 61, a traveling wave tube amplifier (TWTA) 62, and an output multiplexer (OMUX) filter 63, It is composed of an electrical / optical converter and an optical / electrical converter, and the characteristics are made to be non-linear characteristics of the electrical / optical converter and optical / electrical converter that are actually used. Degradation due to the nonlinear characteristics of the converter can be suppressed.

  Moreover, the transmission apparatus in the present invention can also be applied to transmission systems other than OFDM that transmit via a terrestrial repeater.

  For example, in the terrestrial digital broadcasting in the United States and Korea, an 8-value / 16-value VSB is transmitted in which 8-value or 16-value signal points are modulated at equal intervals on one dimension and then half of the spectrum is removed by a filter. The ATSC system employing modulation is used, and there may be a case where the nonlinear characteristic of the power amplifier that finally transmits radio waves becomes a problem. In this case, in FIG. 3 or FIG. 5, instead of configuring the pseudo satellite repeater 6 with an input multiplexer (IMUX) filter 61, a traveling wave tube amplifier (TWTA) 62, and an output multiplexer (OMUX) filter 63, A VSB comprising a VSB filter, a power amplifier, and a VSB detector for performing a predetermined band limitation, and further arranging a VSB filter for performing a predetermined band limitation in front of the quadrature modulation unit 14, suppresses deterioration due to nonlinear characteristics of the power amplifier. A modulator can be configured. In the ATSC system, 8-value / 16-value VSB modulation based on modulation in which 8-point or 16-value signal points are equally spaced in one dimension is adopted. However, the signal point on the IQ plane is set at the origin. If the modulation method is one-dimensionally arranged on a single straight line passing through, a VSB modulator based on the modulation method can be configured. For example, the number of signal points is selected as a power of 2 such as 32, 64, and 128. It is also possible to employ a modulation scheme in which signal points are arranged one-dimensionally at equal intervals or unequal intervals.

  Specifically, in the case of applying to VSB modulation, a transmission apparatus transmits a digital signal by VSB modulation using a predetermined modulation method in order to transmit the digital signal to the reception apparatus via a predetermined transmission path. Can be provided as a transmitting device. This transmission apparatus corresponds to the characteristics of the VSB filter unit (not shown) that performs predetermined band limitation and the target device (for example, the repeater of the real satellite 2) on the transmission line according to the description of the first embodiment. A pseudo transmitter 6 having characteristics, a VSB detection unit (not shown) that performs VSB detection, and a signal point of a digital signal transmitted via the pseudo transmitter 6 to the ideal IQ signal point after mapping from the target device. The deviation of the signal point after passing is obtained as an error vector, the signal point after mapping of the signal point is converted to a signal point corrected with the error vector, and the signal point after mapping of the signal point is A timing delay unit 7 that adjusts timing to correct with an error vector, a VSB filter unit (not shown) that performs a predetermined band limitation on a signal point sequence corrected with an error vector, And a quadrature modulator 14 which quadrature-modulates the output of the VSB filter portion can be configured to suppress degradation due to nonlinear characteristics of the transmission path.

  Furthermore, the transmission apparatus when applied to this VSB modulation has a VSB filter unit (not shown) for performing a predetermined band limitation and a target device (for example, the real satellite 2) on the transmission line according to the description of the second embodiment. A pseudo transmitter 6 having characteristics corresponding to the characteristics of the repeater), a VSB detection unit (not shown) for performing VSB detection, and an ideal IQ signal after mapping from a signal point of a digital signal transmitted via the pseudo transmitter 6 A deviation of a signal point after passing through the target device with respect to a point is determined as an error vector, and a signal point after mapping of the signal point is converted to a signal point corrected with the error vector, and the signal point A plurality of signal point converters 1 arranged in series, with the timing adjustment unit 30 that adjusts the timing to correct the signal points after mapping with an error vector as a set of signal point converters. n and a plurality of signal point converters 1-n arranged in series, a VSB filter unit (not shown) that performs a predetermined band limitation on a signal point series obtained by correcting the signal point after mapping of the signal point with the error vector. And an orthogonal modulation unit 14 that orthogonally modulates the output of the VSB filter unit, and can be configured to suppress deterioration due to nonlinear characteristics on the transmission path.

  Although the above embodiments have been described as representative examples, it will be apparent to those skilled in the art that many variations and substitutions can be made within the spirit and scope of the invention. For example, in the above-described embodiments, the satellite repeater or the terrestrial transmission side amplifier is described as an example. However, such a satellite repeater or the terrestrial transmission side amplifier has a frequency characteristic and nonlinearity of phase and amplitude. Since the present invention can be applied to a repeater, an electric device, an optical device, or a combination thereof having one or more known properties, these are collectively referred to as “target devices”. The transmission path is a signal path from signal modulation on the transmission side to signal demodulation on the reception side. In the above-described embodiment, the pseudo satellite repeater or the pseudo amplifier having the characteristics approximate to those of the satellite repeater or the terrestrial transmission side amplifier has been described. Since any device having characteristics approximating the characteristics of the target device on the transmission path (that is, characteristics corresponding to the characteristics of the target device on the transmission path) can be configured, these are collectively referred to as a “pseudo transmitter”. Further, “approximate characteristics” (that is, “corresponding characteristics”) includes “equivalent characteristics”. That is, the essence of the present invention is to predict the distortion generated in the repeater or the transmission path in advance in the transmission apparatus, and to reduce the distortion component before transmitting to improve the transmission characteristic. Any component of the repeater or the transmission path that causes deterioration may be used. In particular, as described in the embodiment, the present invention is effective in signal transmission of amplitude phase modulation.

  Accordingly, the invention should not be construed as limited by the embodiments described above, but only by the claims.

  According to the present invention, since transmission path distortion can be suitably reduced, it can be configured as a dedicated apparatus such as a non-linear distortion correction apparatus and a digital modulation apparatus, and a digital signal signal via a transmission path having transmission distortion. Useful for processing applications.

It is a block diagram which shows the structure of the transmission system via the satellite repeater with which the broadcasting satellite was equipped. It is a block diagram which shows only the structure of the modulator of the conventional generalized transmitter. It is a block diagram which shows only the structure of the modulator in the transmission apparatus of Example 1 by this invention. It is a figure which shows the vector calculation of the Example by this invention. It is a block diagram which shows only the structure of the modulator in the transmission apparatus of Example 2 by this invention. It is a figure which shows the calculation result of the signal point arrangement | positioning at the time of 32APSK modulation in the transmitter of the Example by this invention. It is a block diagram which shows the structure of the conventional generalized OFDM transmitter. It is a block diagram which shows the structure of the transmission apparatus of Example 3 by this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Transmitter 1-n Signal point converter 2 Real satellite 3-1 to 3-N Receiver 5 Signal point converter 6 Pseudo satellite repeater 7, 7-1, 7-2, 7-2a, 7-2b, 7-3 delay units 7-3a, 7-3b, 7-3c delay units 8, 8-1, 8-2, 8-3 first vector adder units 9, 9-1, 9-2, 9-3 2 vector addition unit 11 modulator 12 serial / parallel conversion (S / P) unit 13 mapping unit 14 orthogonal modulation unit 15 OFDM conversion unit 16 amplifier 17 antenna 18 OFDM conversion unit 19 pseudo amplifier 20 OFDM inverse conversion unit 21 input multiplexer (IMUX) ) Filter 22 traveling wave tube amplifier (TWTA)
23 Output multiplexer (OMUX) filters 30, 30-1, 30-2, 30-3 Vector operation units 61, 61-1, 61-2, 61-3 Input multiplexer (IMUX) filters 62, 62-1, 62- 2,62-3 traveling wave tube amplifier (TWTA)
63, 63-1, 63-2, 63-3 Output multiplexer (OMUX) filters 151a, 151b, 181a, 181b, 201a, 201b Serial / parallel conversion (S / P) units 153a, 153b, 183a, 183b, 203a, 203b Parallel / serial conversion (P / S) units 152, 182 Inverse fast Fourier transform (IFFT) unit 202 Fast Fourier transform (FFT) unit

Claims (10)

In order to transmit a digital signal to a receiving device via a predetermined transmission path, the transmitting device modulates the digital signal with a predetermined modulation method,
A pseudo transmitter having characteristics corresponding to the characteristics of the target device on the transmission path;
The deviation of the signal point after passing through the target device from the ideal IQ signal point after mapping from the signal point of the digital signal transmitted through the pseudo transmitter is obtained as an error vector, and the signal point after mapping of the signal point is Vector calculation means for converting into signal points corrected with the error vector;
Timing adjustment means for adjusting timing in order to correct the signal point after mapping of the signal point with the error vector;
Orthogonal modulation means for performing orthogonal modulation with a signal point corrected by the error vector;
A transmission device comprising: In order to transmit a digital signal to a receiving device via a predetermined transmission path, the transmitting device modulates the digital signal with a predetermined modulation method,
A pseudo transmitter having characteristics corresponding to the characteristics of the target device on the transmission path;
The deviation of the signal point after passing through the target device from the ideal IQ signal point after mapping from the signal point of the digital signal transmitted through the pseudo transmitter is obtained as an error vector, and the signal point after mapping of the signal point is As a set of signal point converters, vector operation means for converting to signal points corrected with the error vector, and timing adjustment means for adjusting timing to correct the signal points after mapping of the signal points with the error vector, A plurality of signal point converters arranged in series;
Quadrature modulation means for performing quadrature modulation with a signal point obtained by correcting the signal point after mapping of the signal point with the error vector by the plurality of signal point converters arranged in series,
A transmission device comprising: In order to transmit a digital signal toward a receiving device via a predetermined transmission path, the digital signal is modulated by a predetermined modulation method and OFDM-multiplexed and transmitted.
An OFDM converter that converts a frequency-axis signal point sequence into a time-axis OFDM signal;
A pseudo transmitter having characteristics corresponding to the characteristics of the target device on the transmission path;
An OFDM inverse conversion unit for converting a time axis signal point sequence into a frequency axis OFDM signal;
The deviation of the signal point after passing through the target device from the ideal IQ signal point after mapping from the signal point of the digital signal transmitted through the pseudo transmitter is obtained as an error vector, and the signal point after mapping of the signal point is Vector calculation means for converting into signal points corrected with the error vector;
Timing adjustment means for adjusting timing in order to correct the signal point after mapping of the signal point with the error vector;
An OFDM converter that converts the signal point corrected by the error vector into a time-axis OFDM signal;
Orthogonal modulation means for performing orthogonal modulation with the time-axis OFDM signal;
A transmission device comprising: In order to transmit a digital signal toward a receiving device via a predetermined transmission path, the digital signal is modulated by a predetermined modulation method and OFDM-multiplexed and transmitted.
An OFDM converter that converts a frequency axis signal point sequence into a time axis OFDM signal;
A pseudo transmitter having characteristics corresponding to the characteristics of the target device on the transmission path;
An OFDM inverse converter for converting a time-axis signal point sequence into a frequency-axis OFDM signal;
The deviation of the signal point after passing through the target device from the ideal IQ signal point after mapping from the signal point of the digital signal transmitted through the pseudo transmitter is obtained as an error vector, and the signal point after mapping of the signal point is As a set of signal point converters, vector operation means for converting to signal points corrected with the error vector, and timing adjustment means for adjusting timing to correct the signal points after mapping of the signal points with the error vector, A plurality of signal point converters arranged in series;
An OFDM conversion unit that converts a signal point obtained by correcting the signal point after mapping of the signal point with the error vector, into a time-axis OFDM signal by the plurality of signal point converters arranged in series;
Orthogonal modulation means for orthogonally modulating a time-axis OFDM signal;
A transmission device comprising:   The transmission apparatus according to claim 1, wherein the predetermined modulation scheme includes ASK, PSK, or APSK. In order to transmit a digital signal toward a receiving device via a predetermined transmission path, the digital signal is VSB modulated by a predetermined modulation method and transmitted.
A VSB filter unit for performing a predetermined band limitation;
A pseudo transmitter having characteristics corresponding to the characteristics of the target device on the transmission path;
A VSB detection unit that performs VSB detection;
The deviation of the signal point after passing through the target device from the ideal IQ signal point after mapping from the signal point of the digital signal transmitted through the pseudo transmitter is obtained as an error vector, and the signal point after mapping of the signal point is Vector calculation means for converting into signal points corrected with the error vector;
Timing adjustment means for adjusting timing in order to correct the signal point after mapping of the signal point with the error vector;
A VSB filter unit that performs a predetermined band limitation on the signal point series corrected with the error vector;
Orthogonal modulation means for orthogonally modulating the output of the VSB filter section;
A transmission device comprising: In order to transmit a digital signal toward a receiving device via a predetermined transmission path, the digital signal is VSB modulated by a predetermined modulation method and transmitted.
A VSB filter unit for performing a predetermined band limitation;
A pseudo transmitter having characteristics corresponding to the characteristics of the target device on the transmission path;
VSB detection unit for performing VSB detection,
The deviation of the signal point after passing through the target device from the ideal IQ signal point after mapping from the signal point of the digital signal transmitted via the pseudo transmitter is obtained as an error vector, and the signal point after mapping of the signal point is obtained. As a set of signal point converters, vector operation means for converting to signal points corrected with the error vector, and timing adjustment means for adjusting timing to correct the signal points after mapping of the signal points with the error vector, A plurality of signal point converters arranged in series;
A VSB filter unit that performs a predetermined band limitation on a signal point sequence in which signal points after mapping of the signal points are corrected by the error vector by the plurality of signal point converters arranged in series;
Orthogonal modulation means for orthogonally modulating the output of the VSB filter section;
A transmission device comprising:   The transmission apparatus according to claim 6 or 7, wherein the predetermined modulation scheme is a modulation scheme in which signal points are arranged one-dimensionally.   The said pseudo transmitter has the setting value of the value which approximated the characteristic of the predetermined input filter in the said object apparatus, an amplifier, and an output filter, It is any one of Claims 1-8 characterized by the above-mentioned. The transmitting device described.   The target device includes a repeater, an electrical device, an optical device, or a combination thereof having one or more known characteristics of phase and amplitude frequency characteristics and nonlinear characteristics. The transmission device according to any one of 9.

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