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216APSK/QAM-OFDM 3.2 Gbps transmitter and receivere circuit diagram of the 16APSK/16QAM-OFDM 3.2 Gbps transmitter and receiver system is shown in Fig. 2.Its specications are shown in Table 1. Figure 3 shows the modulator and demodulator print wired boards. Figure 4-1 shows the 16APSK signal mapping. Figure 4-2 shows the 16QAM signal mapping. As shown in Fig. 5, the 16APSK/16QAM signal is multiplexed into 16 frequencies (subcarriers: f0-f15) and a data transfer rate of 3.2 Gbps was realized.To reduce the eects of inter-symbol interference, which causes distortion in the transmission line, we set 57.14 MHz as the frequency interval and the entire band-width (equivalent noise bandwidth) as 940 MHz. To cancel the eects of amplitude and group delay due to the char-acteristics of the earth station’s communication equipment, the satellite circuit, and the satellite’s transponder, adjust-FiF2　16APSK/16QAM-OFDM 3.2 Gbps RF signal direct-processing transmitter and receiver circuit configurationFiF3　16APSK/16QAM-OFDM 3.2 Gbps RF signal direct-processing modulator/demodulator print wired boardsSpecificationModulation:16APSK-OFDM, GI=2.5ns(radius ratio γ=R2/R1=2.73205),16QAM-OFDM, GI=2.5nsSignal Mapping:DVB-S2 conformity (16APSK)Gray code (16QAM)Data Rate:3,200Mbps=50Msps × 4bit/symbol × 16chError Correcting Code:LDPC codeInterleave:Interleave between subcarriers(every eight subcarriers)Randomizer:Generating polynomialh(x)=x8+x7+x5+x3+1 (CCSDS)10GbE exter-nal interface:10GbE SFP+ interfaceInternet Protocol: UDP/IPBit Rate: 3,200Mbps(after adding error correction)TabT1Major specifications of 16APSK/16QAM-OFDM 3.2 Gbps RF signal direct-processing transmitter and receiverMOD PWBDEMOD PWB3 Ultra-High-Speed Satellite Communication Technology112　　　Journal of the National Institute of Information and Communications Technology Vol. 64 No. 2 (2017)