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compensation technique for the satellite, because relatively little computation can suciently compensate the distor-tion[2]. Figure 1 shows a conceptual diagram of the distor-tion compensation by the DPD. On the one hand, the compensation for the wideband signal requires high-speed operation because the compensable signal bandwidth by the DPD depends on the operation clock of the device, and in fact, it is dicult to remove all distortion components (spectrum re-growth) generated in the range out of the bandwidth. Accordingly, it is necessary not only to remove the distortion components due to the DPD but also to attenuate the radiation component out of the bandwidth by the band-pass lter (BPF), etc. located between the amplier and the antenna.3Communication experiment configuration and overviewTo conrm the performance of the non-linear distor-tion compensation with the DPD circuit, we experimented with the use of the bent pipe link, which uses the multi-beam antenna (MBA) of the wideband internetworking engineering test and demonstration satellite “KIZUNA” (hereinaer called WINDS), as the satellite link of the same Ka band — dierent from the frequency band allocated to the Earth observation satellite. Figure 2 shows the experi-ment system diagram at the time. In addition, Fig. 3 shows a photo of the breadboard for the modulation with the DPD function.e modulated signal output from the breadboard for the modulation is up-converted to a signal of the 3 GHz band, and connects to the input port of the IF patch in the ground station of the NICT Kashima Space Technology Center[3] (hereinaer called Kashima station), Kashima city, Ibaraki prefecture. e Kashima station up-converts the signal of the 3 GHz band to the 28 GHz band, the high-power amplier (HPA) amplies the signal, and then the signal is sent from the antenna to the satellite. e WINDS converts the received signal frequency of the 28 GHz band to the frequency of the 18 GHz band, ampli-es the signal power, and then sends the signal back to the Kashima station of NICT. e Kashima station down-converts the signal of the 18 GHz band received from the WINDS to the 3 GHZ band, and outputs it from the IF patch. In addition, the Kashima station has a frequency translator (hereinaer called “translator”) path as the path without using the satellite. e translator path is one to down-convert the up-converted signal of the 28 GHz band to the 18 GHz band and to connect to a reception path. e WINDS and translator paths can be changed by a switch. To observe the dierence of the signals passing two dierent paths can evaluate the eect of the satellite com-munication path.e received signal of the 3 GHz band is input to a receiver aer being converted to 1.2 GHz frequency. e receiver used the cortex high data rate receiver, made by Zodiac Data Systems, available as a receiver for the Earth observation satellite[4]. e non-linear compensation performance by the DPD circuit was evaluated by BER (Bit Error Rate) at the demodulator. e high-power ampliers respectively exist in the Kashima station and the satellite in the WINDS path, and the operating point of these ampliers changes by radio attenuation due to clouds, etc. erefore, the non-linearity of the satellite communication path cannot be identied in advance. For these reasons, we decided to estimate the non-linearity of the satellite com-munication path by the received constellation distribution to x the corrective coecient of the DPD. We set the data sequence to be sent to the 15-stage pseudo-random noise (PRN 15) which does not include an error-correcting code, and measured the BER aer the receiver bit-synchronized to reset the bit error counter to zero (zero-reset). At the time, the ratio of signal power per bit vs. noise power FiF3Appearance of trial-product board equipped with non-linear distortion compensation circuitParameterValueRemarksSymbol rate340, 450 MspsSelectableData patternPRN (Pseudo-Random Noise)15-stageRoll-off rate0.4Root-raised-cosine filter common to sending and receivingModulation scheme16 QAMTabT1　Main experiment parameters1473-9 Experiment of Non-Linear Compensation on Satellite Channel