About me

Andrew Casper

My name is Andrew Casper, I’m currently a graduate student with the Ultrasonic Imaging and Signal Processing Laboratory at the University of Minnesota. My research involves work with ultrasound phased arrays and covers a broad range of topics. My work can be roughly broken down into two main categories: hardware, software, and algorithm development and acoustic modeling.

The arrays I work with are typically high power arrays which have been specially designed to both deliver High Intensity Focused Ultrasound (HIFU) and image ultrasonically with the same elements, a so-called Dual Mode Ultrasound Array (DMUA). Part of my research has been on designing and implementing custom hardware to both excite and receive signals from these arrays. In tandem with this hardware development, I’ve designed the software and firmware to filter, beamform, and analyze this data in real-time, resulting in a one of a kind DMUA research platform.

I also work on acoustic modeling of ultrasound propagation through inhomogeneous media. This research focuses on using GPUs to implement high-speed 2D and 3D simulations for use in reconstructive imaging and array focusing.

Outside of my studies, I like to fool around with microcontrollers, FPGAs, and generic programming on personal projects of various complexity. This blog is meant to chronicle some of those projects, primarily for myself, but I’m hopeful that they will also be of interest to at least a few others. If you have any questions, comments, or suggestions feel free to email me at casp0069@umn.edu.

  1. Vineet Srivastava

    Hi Andrew,

    I just came across your blog. You have been doing fantastic work, really. I am truly inspired looking at your work.

    As part of a personal (read hobby) project, I am presently looking at a SDR platform that I may use to access I/Q signals, say in the GSM (900/1800) or WLAN (2.4 GHz bands). Only receiver is fine for me. Was wondering if you may have some suggestions.

    Thanks again for documenting your experiments as neatly as you are. I will surely visit your site more often.


    (Bangalore, India)

    • Hi Vineet,

      I’m glad you enjoyed the blog, I’ve been out of town for the summer so I haven’t had a chance to post any new material. Once I get back to Minneapolis I hope to post about some more interesting projects. As for commercially available SDRs, if I were going to buy one, I would probably get the QSR1 (http://www.srl-llc.com/). I’ve not personally used this SDR but from the specs and the reviews I’ve read, it seems to be very powerful and available a reasonable price. You will, however, still need some sort of down conversion to get into the frequency ranges you want to inspect as this board can only undersample up to 500 MHz. Good luck with your project, it sounds like fun!


  2. Andrew,

    I’ve been looking at you free-fall experiment with the high speed camera with great interest and the level of detail you’ve provided in your write-up is what makes it all incredibly interesting. I’m an amateur physicist with a keen interest in gravity and I was hoping to find some experimental data on the Net taken with one of the new ultra high speed cameras. My interest is in the first 10 milliseconds or so of free-fall. Do you know of any online data set that is available for download, taken with a camera resolution down to the millisecond level. Would you be willing to provide me with the raw unfiltered data from your experimental run, as your 4 ms data is still an order of magnitude better that any other data-set I can find on the Net. I would need your raw unfiltered data as I believe the filtering process is hiding some of the underlying physics, which is precisely the area I’m interested in. Well done and keep up the good work!


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