Introduction to the RF Downlink Transmitter
Interview with TESAT Spacecom on the transmitter development
High Rate RF Downlink Transmitter
The Hi-SIDE high-rate RF downlink transmitter is used for high speed data transmission from earth observation or data relay satellites to the ground. The envisaged downlink data rate capability is 10 Gbps when using two transmitters in a dual polarization configuration in Ka-band (25.5 – 27 GHz).
Within the Hi-SIDE project TESAT is responsible for the development and the provision of the high-rate RF downlink Transmitter as a part of the overall system demonstrator. The downlink transmitter demonstrator system includes a 1 GBaud/5 Gbps Ka-Band Modulator (provided by TESAT), a 2 W Ka-Band SSPA (provided by ERZIA) and a ground station demodulator (provided by Kongsberg Space Ground Systems). The following figure shows a system block diagram as well as the contributions of the partners:
Hi-SIDE RF Downlink System
The demonstrator test set-up of the Hi-SIDE high-rate RF downlink transmitter is shown in the figure below. The Modulator concept is based on IF sampling with subsequent up-conversion to Ka-Band and amplification by an SSPA.
Hi-SIDE High-Rate RF Downlink Transmitter
Performance of RF Downlink Transmitter:
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Carrier Frequency Range 25.5 to 27 GHz
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Modulation/Coding SCCC/APSK according to CCSDS 131.2-B-1
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VCM/ACM capability yes
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Symbol Rate 1 GBaud
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User Data Rate 5 Gbps
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RF Output Power 2 W
Achievements:
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Manufacturing and integration of Modulator and SSPA finalized (see Figure 1)
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Successful modulation at a symbol rate of 1 GBaud corresponding to user data rate of 5 Gbps
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Successful end-to-end data transmission via SpaceFibre, Modulator and SSPA to Demodulator with data retrieval (data dump to files).