First, thanks for buying our book. I hope it's been a useful read.
I've worked with most of the common microprocessors and considered most before I settled on the Teensy 4.1. There are a bunch of reasons why I chose the Teensy. First, it has the resource depth (e.g., memory and I/O pins) necessary to do a "real" SDT. Second, it has the requisite horsepower: a 600MHz clock and floating-point processor. Third, it is supported by a robust library that will do almost all major tasks and I "trust" its libraries. Fourth, the Teensy 4.1 board is well-defined while others are not (e.g., the ESP32 boards have dozens of variations and not all ESP32 libraries work with all boards--indeed, some boards have 32 pins, others have 38). Fifth, it works in the current IDE and PRJC makes a real effort to keep it and the supporting libraries current with the IDE. And sixth, it supports the RA8875 display, which gives us a choice of 5", 7", or 9" display. All of the above combine to give the T41 a feature set that is unlike other SDTs (e.g., we can show a 192KHz bandwidth).
That said, the purpose of the book is to bring much of the DSP theory into one place, discuss it, and show why we elected to use the circuits we do. We've tried to write the book in an "approachable" manner, making the reading a bit easier than most DSP books, but still giving the reader what they need to know. The book, and the T41, are a jump-off point and we encourage experimentation. Indeed, much of the improvements in the T41 over the past two years are from posters to this site. Developments in the STM32, ESP32, and RP families continue to improve their performance stats to the point where they become viable alternatives to the Teensy 4.1,. We hope others pick up the essence of the T41 and continue to run with it.
Jack, W8TEE
jjpurdum