“Using the same antenna hardware we had used for data rates of 800 Mbps on earlier satellites, we built a communications system capable of 1200 Mbps,” Cubbedge says. “With Simulink, for the first time I can see past the noise effect and understand how distortion is affecting the link.”ĭata rate increased by 50%. “Simulations with our previous software took so long-days for a single data point-that I could never gauge the effects of distortion,” says Cubbedge. “Plus, Simulink models are much easier to instrument, so we can quickly see carrier phase offset, bit synchronization, or any other detail as the simulation runs.”ĭistortion effects included in simulation. “For simulations, Simulink is 10 times faster than the communications systems modeling package we used previously,” says Cubbedge. The team is currently using Simulink to model and simulate the WorldView-4 communications system. Using DSP System Toolbox™ and Communications Toolbox, the team conducted spectral analysis, and produced eye diagrams, vector scatter plots, and constellation plots to visualize simulation results and analyze system behavior.ĭigitalGlobe has completed development of the communications system for WorldView-3, achieving the target data rate of 1200 Mbps. Additional simulations were used to analyze effects due to distortion, the environment, and the satellite’s elevation. To verify that the system had a bit-error rate of less than 10-6, they ran simulations in Simulink in which 10 million bits were transmitted. The models also enable them to trade off filter bandwidths with equalizer complexity. They used the models to evaluate how RF effects affected baseband data rates. They modeled the amplifier and other RF components using RF Blockset™ and RF Toolbox™.
They used the Filter Design and Analysis app in Signal Processing Toolbox™ to design and calibrate the system’s Butterworth filter. The engineers used Communications Toolbox to model the receiver’s adaptive equalizers using an LMS algorithm running in decision-directed mode. The encoding and decoding components were modeled using Reed-Solomon encoding and decoding blocks from Communications Toolbox™. The end-to-end Simulink model included an amplifier, an 8-PSK modulator and demodulator, an encoder and decoder, filters, equalizers, and the space-to-ground channel, modeled as additive white Gaussian noise. SolutionĭigitalGlobe engineers modeled the complete communications system for their newest satellite in Simulink and performed extensive simulations to ensure reliable performance at 1200 Mbps data rates. DigitalGlobe sought a less expensive alternative that would be faster and easier to use. With this package, BER simulations could take weeks, and licensing costs were high. In the past, DigitalGlobe engineers working on similar projects used an off-the-shelf software package for communications systems modeling.
Further, as they moved from QPSK to an 8-PSK modulation scheme, they needed to accurately model cross-polarization interference to ensure there was enough link margin for the system to operate reliably. The team needed to implement filters with steep edges, but such filters can distort the signal. To avoid interfering with DSN signals, DigitalGlobe engineers had to meet stringent out-of-band emissions and power requirements, even as they sought to increase their downlink data rate from 800 Mbps to 1200 Mbps for WorldView-3. Headquarters are located in Tysons Corner, VA.DigitalGlobe communications systems operate in the X-Band between 8.025 and 8.040 GHz, which is adjacent to the frequency band used by the Deep Space Network (DSN). Executive Mosaic offers highly coveted executive events, breaking business news on the Government Contracting industry, and delivers robust and reliable content through seven influential websites and four consequential E-newswires. “Fully automated mapping holds the potential to unlock tremendous value for our customers, and we look forward to continuing to support future open innovation initiatives to move the community forward, ” he added.Ībout Executive Mosaic: Founded in 2002, Executive Mosaic is a leadership organization and media company. “The first SpaceNet Challenge proved we can attract talented developers and data scientists from around the world to bring expertise to the GEOINT community, ” said Tony Frazier, senior vice president for government solutions at DigitalGlobe. The winners of the SpaceNet Challenge will receive $35, 000 in total prizes and will have their algorithms released to the open-source community via the SpaceNet GitHub repository and DigitalGlobe’s GBDX Geospatial Big Data platform, DigitalGlobe said Tuesday. 12, 2017 - DigitalGlobe (NYSE: DGI) has selected the top five developers who took part in its machine learning algorithm development challenge using satellite imagery, ExecutiveBiz reported Wednesday.
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