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• Setting up for FPGA programming

  Aritz Erkiaga • 12/22/2024 at 18:16 • 0 comments

  For my last prototype, I used a Tang Nano 20K FPGA board, and programmed it in Verilog using the open-source Yosys synthesis suite. This time, to improve on this workflow, I'm learning Chisel; I've started with the task to write a basic primitive library for the Gowin family of FPGAs (which the Tang boards sport). I've dived a little more into Yosys code and done a couple of changes to it. Now I've ordered a less powerful Tang Nano 1K board to begin testing.
  

• Improved simulations

  Aritz Erkiaga • 12/12/2024 at 23:27 • 0 comments

  After improving the physical aspect of the simulation, as well as tuning the data processing algorithm (filtering region-of-interest correlation data and trying different diagonal loading coefficients before matrix inversion), image quality was greatly enhanced.
  

  
  The four short bright lines are where ultrasound-reflecting surfaces are located in the simulation. Other than a few artifacts, especially near the sensor, everything seems to keep its original shape.

  Only an actual experiment will tell how well real tissues show themselves with the chosen parameters, but at least this preliminary test hasn't given any reason to worry yet. It should work nicely once realized.
  
  

• Simulations using Python

  Aritz Erkiaga • 12/10/2024 at 13:21 • 0 comments

  Using a Python script, I've tested the effect of different parameters and algorithms on the quality of the ultrasound image. Here is a 100 x 100 test with 50 elements, beam focusing on a 16 x 16 point grid, MVDR beamforming, de-modulated signal, 1 MHz fundamental imaging.

  
  It's not easy to simulate the propagation of ultrasound in tissues, so this picture is a greatly simplified, unrealistic approximation with lots of noise. But a real device with the same parameters should produce something at least as good as it, and I now have reference code for such a device.
  

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