Hi, author here. I must say I'm not 100% confident in everything the STM32s do - and the rp2040/rp2350 is an easy one. One of my pieces of work is : continuous acquisition, acquisitions, processing, and writing on a fast storage, which allows for continuous 10MB/s+. All of this can be managed through the 2 cores, and the PIOs.
In short, PIOs are really a game changer, I have dumped a FPGA from the previous iteration to go rp2040.
BUT... solutions like some of PIC32 and their integrated 40Msps ADC are really nice and worth exploring (if I had the time). The positive thing about the pico is that it's so common and tools are so common that it's really a pleasure developping on this device =)
As a way to go around this issue, I sense a bit of progress through compressed sensing, see for example http://advances.sciencemag.org/content/3/12/e1701423 . This would enable one (with enough horsepower) to get 4D imaging with a single element. This is very early, but I do plan on using this hardware to test the feasibility of single-piezoelement pseudo-imaging.
Could be indeed!
Augmented sensing, there's definitely something one can do. A ping (radar-like) every 5s, and in time you listen to echoes. The more intense, the higher the frequency.
Ping me through the contact in the doc if you're keen on discussing about this!
The point being that on these experiments, the sensor isn't an array of piezos, rather a single-element piezo. Cuts the costs (a fab invoices around 100-200e for such a sensor), but lowers the overall image quality.
Before trolling a bit, I remember the main costs don't come from hardware (though it definitely costs something) - rather for r&d, patents, and most of all proper certification, since, in the end, it's a matter of life and death.
That being said, this experiment is mostly a dev kit to help curious tinkerers explore the topic :)
Hey! Theres a link for tindie in the doc. It's quote expensive, high voltage being the main reason, but I'm planning on reducing the costs and have a cheaper on-board extension for the pi once this hardware stabilizes