Demonstration of multi-Gbps data rates at Ka-band using software-defined modem and broadband high power amplifier for space communications

The paper presents the first ever research and experimental results regarding the combination of a software-defined multi-Gbps modem and a broadband high power space amplifier when tested with an extended form of the industry standard DVB-S2 and LDPC rate 9/10 FEC codec. The modem supports waveforms including QPSK, 8-PSK, 16-APSK, 32-APSK, 64-APSK, and 128-QAM. The broadband high power amplifier is a space qualified traveling-wave tube (TWT), which has a passband greater than 3 GHz at 33 GHz, output power of 200 watts and efficiency greater than 60%. The modem and the TWTA together enabled an unprecedented data rate at 20 Gbps with low BER of 10^-9. The presented results include a plot of the received waveform constellation, BER vs. E_b/N₀ and implementation loss for each of the modulation types tested. The above results when included in an RF link budget analysis show that NASA´s payload data rate can be increased by an order of magnitude (>;10X) over current state-of-practice, limited only by the spacecraft EIRP, ground receiver G/T, range, and available spectrum or bandwidth.