In bitluni's latests phased array ultrasonic video Click Here for Board Design Section. While I understand that he is using some sort of "amplifier" to drive the transducer(since they need more current than the ESP32 can supply), how does he generate the 40khz pwm signal, precisely out of phase? Is he doing this manually, through code(manually setting highs and lows with delays in software), or through some sort of multiprocessing(threads, but I'm not sure how he can change that precisely), or is he shifting the signals out of phase with hardware(like with IQ Modulators)?
Did you ask him?
The Motor Control Pulse Width Modulator (MCPWM) - ESP32 - — ESP-IDF Programming Guide latest documentation (espressif.com) is one way it can be done with a ESP32.
Hmm I see, but it looks like on the page that a max of 6 pwm outputs can be driven, but bitluni has 8 ultrasonic transducers, and his boards seems to have 0-7 numbered, each for one transducer. Any idea how he drives 8 transducers?
Thank you for the response though!
Why focus on one developer? How do you even know if it's a competent project? Think out of the box and look for similar projects and devices.
I cannot answer your query.
But I woud like to add that is the best beamforming visualisations I have seen. A shame I didn't see something like that 38 years ago when I was designing receiving analogue beamformers. 
I finally found some time to view part of the video. It's impressive, but shy on details. I think that is intentional. It seems to me, a probably successful attempt to monetize some research with YouTube exposure and maybe sponsorships. Thus I think it is unlikely that you will get more information from him.
That just reinforces my suggestion - just take it as a demo, follow the few links that he does provide, and do independent research.
Finally, when you do get it working - put everything in the public domain so other people can really access your research. Think about your own situation now, you are interested but haven't been given any solid information to go forward with.
While I think that guy might be quite brilliant and might stimulate some interest in STEM generally and ultrasound in particular, this kind of commercialization and subtle proprietization really turns me off. It's really not friendly to "the hobby", where people at least should have a more sharing mindset.
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The video is an OK introduction to beamforming, but doesn't seem to contain any useful information on how the author's circuit was designed or actually works. Unless he publishes a complete schematic and the code, you have to do everything yourself.
Like @anon57585045, I was put off by the author's shameless self promotion and narcissism.
There are countless resources on the web about beamforming, so have at it!
Hint: you don't need multiple transducers to do it, either. One works. Look up "synthetic aperture radar" (or sonar).
Any idea how he drives 8 transducers?
The chips on the board.
A quick guess on
Perhaps a trigger sent individually to each US driver. I'm thinking the uC sends a timed pulse from an 8-bit port to the transducer drivers.
Drive them with the LEDC API.
I see, I think each LED PWM controller has 8 outputs, but how are the phase of the signal changed?
No, he specifically states these are ultrasonic producers, not transducers. He has ONLY a single receiver unit.
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