Sreshtaa Rajesh
What does your research focus on?
I predominantly build test beds that emulate waveforms over RF. Our group leverages these test beds to validate the performance and compatibility of hardware and software implementations of SATCOM terminals and/or payloads before their deployment and during their lifetimes. We frequently collaborate with industry and academic partners to produce and share the technology we develop.
What are examples of projects you've worked on?
I co-built a full-system emulator that mimics realistic signaling environments to prove the efficacy of a waveform our group developed to communicate with a LEO [low Earth orbit] satellite constellation. Our emulator applies all relevant atmospheric and motion-derived channel impairments, as well as interference from jammers, such that we can simultaneously emulate hundreds of emitters over a geographic region alongside a full LEO constellation in orbit. The RF output of the system emulator captures the overall signal observed by each antenna element on an array located at the receiver; this output can be fed into payload implementations under test to validate their performance in custom scenarios.
Designed for rigorous testing of fully realized payload implementations of the waveform against real-world scenarios, this system emulator runs on an industry-grade server rack with powerful GPUs [graphics processing units] to enable signal processing at scale using parallel computing. Custom in-house hardware serves as the multichannel RF interface. My team also designed a lightweight alternative to our full-system emulator to support earlier stages of terminal/payload development through continuous validation of waveform compatibility. This test asset only requires a laptop and a commercial off-the-shelf software-defined radio.
More recently, I've been leading the software build for a new platform that emulates multiple co-located transmitters all transmitting the same waveform. The software emulator interfaces with a high-power radio front-end to transmit the emulated signal over the air. Intended to be distributed to multiple locations across the country for coordinated testing, this platform will support stress-testing the receiver backends of operational satellite constellations.
How did you become interested in STEM and your field of study?
I often jokingly attribute my interest in STEM to growing up with the "Magic School Bus" book series and TV show, but there's a lot of truth to that. That show had me rattling off the names of planets in the solar system and organs in the digestive system before I was in kindergarten. My curiosity about science only grew as I got older. My parents also took me to a couple of the Lab's Science on Saturday programs, which put the Lab on the map for me as a middle schooler. I clearly never forgot about it!
My field of study in undergrad was computer science with a focus on low-level systems/architectures and compilers. As a computer scientist, I enjoy the versatility in applying my expertise to various domains, ranging from programmable medical devices and privacy-preserving compilers to now SATCOM.
Where have you traveled and/or would like to travel?
My favorite places I've traveled to are Banff and Jasper National Parks in the Canadian Rockies. Words cannot express the sheer majesty of the views there, and I would absolutely go back. As for future travel, I'd love to visit New Zealand. I'm a massive fan of "The Lord of the Rings" movies, and seeing the various filming locations, especially the mountain range where the beacons were lit in the third movie, is high on my bucket list.
What are you passionate about outside of your technical work?
I'm passionate about the impacts of anthropomorphic climate change on communities globally. As extreme weather becomes more common and natural disasters increase in number and magnitude, one of the most pressing threats to national and global security will be the downstream effects of weather and climate. Addressing these effects will require the best interdisciplinary minds to come together. At the Lab, I see those minds all around me. I hope that, in the years to come, the Lab plays a larger role in developing technology for predicting, detecting, and mitigating climate-related risks to the global population such as food/water insecurity, infrastructure vulnerability, and supply-chain disruptions.
What are your hobbies?
I'm an avid knitter. I find knitting therapeutic and engaging, and it’s helped me discover my own sense of fashion and style. Catch me in the winter, and I'm probably wearing a sweater that I hand-knit. In the summer, I enjoy spending time outside in any capacity, whether to jog or cycle or to lounge in the sun with some ice cream. I'm also trained in South-Indian classic vocal music and dance, both of which I perform a few times a year. Recently, I've gotten into sourdough baking, and I hope to expand my sourdough horizons to more exotically flavored loaves!