Two main application scenarios were identified for flexible satellite communication payloads: Very HTS (VHTS) and Software defined payload satellite, using active antennas. Selected target was a photonic payload operating at extremely high frequency (W band) and with high capacity (1 Tbps) and fulfill the requirements for the VHTS scenario.
The PhLEXSAT payload concept was defined incorporating advanced broadband photonic ADC and photonic DAC with DSP with high degree of miniaturization and power-consumption efficiency.
According with the above system requirements, the specifications were defined and the design was performed of the different units integrating the PhLEXSAT demonstrator.
A test plan was generated at module and unit level, determining the type and conditions of the assessment tests for the space environment up to TRL5.
One MZI PIC capable to operate in DC-86 GHz and four HL-PD array PIC with linearity optimized in DC-6, 17-20, 37.5-42.5 and 71-76 GHz, respectively, were designed, manufactured and tested. Furthermore, two packaged MZI PIC versions were manufactured, one DC-86 GHz for the Photonic ADC, the second one DC-6 GHz with additional RF amplifier for the Photonic DAC. Four packaged HL-PD PICs versions were manufactured, three 17-20, 37.5-42.5 and 71-76 GHz for the Photonic DAC, another DC-6 GHz with additional RF amplifier for the Photonic ADC.
One Photonic ADC-PD unit and two Photonic DAC-PD units were manufactured and tested, integrating the corresponding HL-PD modules.
One Photonic ADC-MZI unit and one Photonic DAC-MZI unit were manufactured and tested, integrating Commercial off-the-shelf (COTS) MZI. The units are ready to directly replace the COTS MZI by the PhLEXSAT MZI modules.
Photonic Clock unit was manufactured and tested based on a mode-locked laser at 2.6 GHz, optical amplification and splitting to provide a clock to the MZI units for photonic sampling.
All units were integrated with electronics and control firmware as well as mechanical interface.
DSP modules were developed and tested on FPGA hardware, including ADC and DAC interfaces, linearisation, channelization and multiplexing. Embedded and user interface software were developed and tested to control the PhLEXSAT demonstrator.
PhLEXSAT demonstrator was integrated including the photonic units with control software and power supply. Test results showed the correct behavior of the RF to optical back to RF conversion. The achievements are summarized below:
Photonic ADC in the Ka band (27.5-30 GHz), although the same concept can be applied to V/W bands.
Photonic DAC in the Q (37.5-42.5 GHz) and V (75-76 GHz) bands, although the same concept can be applied to the Ka band.
Photonic ADC (27.5-28.75 GHz) connected to Photonic DAC (41.25-42.5 GHz).
