Planet High Speed Radio: Crossing Gbps from a 3U CubeSat

Planet is a vertically integrated aerospace and data analytics company that operates the world\u27s largest commercial fleet of remote sensing satellites. Our mission is to image the whole world everyday, and make change visible, accessible, and actionable. We have launched over 350 satellites and built up an automated mission control and ground station infrastructure to monitor and control the satellites, and download the imagery data. Historically, small satellite radios have been downlink limited because of tight size, weight, and power (SWaP) constraints. Rapid prototyping, iteration, and adaptation of the latest commercial-o_-the-shelf (COTS) technology has allowed for continuous improvements in data throughput on our high speed radio from a very low-cost cubesat platform. In this talk, we will report on our latest X-band radio and antenna solution which has achieved a data rate over 1.6 Gbps from a 3U CubeSat on-orbit. Planet\u27s High Speed Downlink 2 (HSD2) is the latest generation compact, low-mass, and low-power radio that was built and deployed on 3U form-factor imaging CubeSats in December 2018. This system operates at X- band and is built using COTS parts with a dual polarization antenna. The two physical channels represent the two polarization modes, right hand circular polarization (RHCP) and left hand circular polarization (LHCP) and each physical channel utilizes 300 MHz of total bandwidth. Within each physical channel, there are three logical channels spaced 100 MHz apart center-to-center frequency. The individual channel symbol rate is 76.8 Msps. Each physical channel has 1 W RF output power and 15 dBi antenna gain. The total DC power consumption of the radio including the processor and the FPGA is 50Wand the total volume occupied by the radio and antenna, including the mechanical deployment structure for the antenna is 0.25U. The commercial digital television broadcasting standard DVB-S2 is used for modulation and coding. An adaptive coding and modulation (ACM) scheme is used to dynamically change the modulation and coding for each channel individually based on the available link margin. Our ground station network includes 15 dishes (29 dB/K gain-to-noise-temperature) across 5 sites located around the world. The HSD2 is capable of providing downlink volume of over 80 GB during a single ground station pass