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taneously with a 2K signal on the VSAT side and goes through the WINDS satellite. A LET antenna receives these two waves. e center frequency of the wave modulation signal from the LET for uplink is set to 28.07 GHz and that from the VSAT is set to 28.03 GHz. e frequency spacing for each channel is 40 MHz. e center frequencies corresponding to these two waves for downlink were 18.27 GHz and 18.23 GHz, respectively. An exterior view of the LET and the VSAT is shown in Figs. 3 and 4 shows the reception spectrum for the 1 GHz band BS-IF signal.2.3Transmission performance results (physical layer)C/N vs. BER characteristics at the WINDS satellite loopback [LET—WINDS—LET and VSAT—WINDS—LET] are shown in Fig. 5. Modulation schemes for evalu-ation were 16-APSK (3/4), 16-APSK (7/9), and 32-APSK (3/4). First, when comparing the required C/Ns (@1 E-11) on the LET and VSAT channel, those on the VSAT were worsened by around 0.2–0.5 dB. Next, when comparing the required C/Ns at the IF loopback and WINDS loopback [VSAT—WINDS—LET] for 16-APSK (3/4), 16-APSK (7/9), and 32-APSK (3/4), those at the WINDS loopback were worsened by 1.0 dB, 1.1 dB, and 1.6 dB, respectively; and, accompanying multi-leveling, there tended to be a large impact over satellite accompanying multi-modulations. Further, it became possible to transmit with a C/N margin for all modulated signals because the required C/N for 32-APSK (4/5) at the WINDS loopback was about 15.9 dB; it is estimated that received C/N was more 20 dB from the reception spectrum in Fig. 4.2.4Syncing functional verification results (transport layer)Next, we verify the syncing functionality by MMT when using the modulated signals for which reception performance has been conrmed. e main video signal as 4K on the LET channel was received by MMT receiver #1 in Fig. 2, decoded, and displayed. e secondary video signal as 2K on the VSAT channel was received by MMT receiver #2, decoded, and displayed. Synced timing of 4K video and 2K video by MMT function is shown in Fig. 6. Further, for performance verication of the function, vari-able delay was set at the MMT streamer output on the VSAT channel to verify the syncing functionality. e result of syncing performance for time delay on the VSAT chan-nel is shown in Table 2. From the result, we conrmed that two video signals could be synchronized even with a FiF3　Exterior of LET and VSAT antennaFiF5　C/N vs. BER characteristics at WINDS satellite loopback (ISDB-S3)LETVSAT1.E‐111.E‐101.E‐091.E‐081.E‐071.E‐061.E‐051.E‐041.E‐031.E‐021.E‐0191011121314151617BERC/N [dB]16APSK 7/9 WINDS‐loop (mod.@VSAT)16APSK 3/4 WINDS‐loop (mod.@VSAT)32APSK 4/5 WINDS‐loop (mod.@VSAT)16APSK 7/9 WINDS‐loop (mod.@LTE)16APSK 3/4 WINDS‐loop (mod.@LTE)32APSK 4/5 WINDS‐loop (mod.@LTE)16APSK 7/9 3GHz‐loop IF16APSK 3/4 3GHz‐loop IF32APSK 4/5 3GHz‐loop IF1.E-111.E-101.E-091.E-081.E-071.E-061.E-051.E-041.E-031.E-021.E-0191011121314151617BERC/N [dB]VSAT lineLET lineLocal loopback (3-GHzIF)16APSK (7/9)16APSK (3/4)32APSK (4/5)VSAT lineLET lineLocal loopback (3-GHzIF)VSAT lineLET lineLocal loopback (3-GHzIF)FiF4　Reception spectrum (1 GHz band BS-IF signal)FiF6　4K and 2K video synchronization by MMT1213-6 SHV Transmission Experiments