Satellite Transmission Encoder and Interleaver (ViaSat Internship 2012)

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ViaSat Inc.[Jordan Corey | jordan.corey@viasat.com] – Signal Transmission  Software Intern 6/12- 9/12

  • Designed and coded 8 PSK and 16 APSK encoding schemes, achieving higher throughput, and designed and coded Reed-Solomon encoder for more robust data transmission for a commercial satellite network
  • Designed and verified system test showing improved throughput and robustness for implemented changes 

This was a particularly challenging internship experience as we had to design and implement a way to encode and interleave messages on the existing ViaSat commercial satellite architecture. We started by dumping the entire project into Eclipse and spent a couple weeks sifting through thousands of files to understand how the existing architecture works. I definitely got really good as using “grep -r …” when the nice Eclipse functions didn’t work out :P.

I thankfully was working with a UCLA Masters student, Christina Yin, and a UCSD PhD student, Yujia Wang, who were more experienced in understanding the existing satellite architecture and designing the encoding and interleaving schemes. My main contribution was understanding where in the existing C code we needed to make the modifications, and then to make those updates and test them.

I also designed a system test to validate our work, using a signal generator and noise filters to stress test our newly implemented encoding and interleaving. I loaded our new software onto a modem and and tested away! We were able to maintain robust signal transmission with much lower signal to noise ratio than normally acceptable by legacy QPSK and BPSK without interleaving. (The graph in the upper middle demonstrates this, with SNR decreasing moving right on the X axis.)

The benefit of this work is that the ViaSat commercial satellite network was able to achieve much higher throughput and was more reliable, especially in the cases of video transmission which we demonstrated in our presentation. As with most things in engineering, there is a compromise for every advancement: in our case we required more power for signal transmission and a bit more overhead.

Overall, we were able to complete the goals set forth by our mentors and then some, going beyond their expectations. I developed more hands-on experience in C and system test and learned quite a bit about encoding and interleaving theory.

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