ESP32 Based SDR Transmitter - Part 2 Tayloe Encoder

[@rfdave3980]

It's ok if you run long videos I don't mind. Very interesting, so enjoyed it. Can't wait for the next episode ...

[@na5y]

heh - thank you. They get a bit painful to edit when they are long also...

[@rfdave3980]

@@na5y Yeah I can see that. By the way if you set the frequency below 5 MHz in your code . The value of mult =150. In the source code for the SI5351 setting the Phase is a uint8_t with the MSB masked off. So the value can only be 0 to 127. I am sure you already knew that. Thanks for the videos

[@na5y]

@@rfdave3980 I didn't know that actually - thanks for pointing out. I do like the si5351 but I often wonder if a simple d-type flip flop to produce the quadrature LO would be easier.

[@rfdave3980]

@@na5y I have set the frequency for the 80M band. You also have to change the PLL Low frequency from 600MHz to 380 MHz which Charlie Morris ZL2CTM has pointed out.

[@yakovdavidovich7943]

Nice, I built a similar IQ modulator with FSAU3157s not too long ago; had very similar results. I noticed at 4:30 that the blue trace is substantially higher amplitude than its counterpart 180-degrees away. In addition to the one trimmer for IQ balance, you might want to add a trimmer in the feedback path for one opamp in each channel so you can adjust balance there too.

[@na5y]

I noticed that blue trace too! I assumed at the time it was the scope probe (I have been having some problems with my probes - they are getting old). Interesting suggestion on putting a 10k multiturn pot in the feedback path. I was hoping to get away with doing it all in the ESP32. Thank you for the comment Yakov

[@alteriaautomation6867]

May I ask what version of the ESP32 SIP are you using. It looks you are using the new ESP32 with I2S. Is that still a dual core? Could you dsisclose the part number? Thanks in advance

[@na5y]

Hi there - The part number is 211-161007 and yes it has I2S and a dual 240Mhz core. The board is the 15 pin variety available all over amazon. For example: www.amazon.com/ESP-WROOM-32-Development-Dual-Mode-Microcontroller-Integrated/dp/B07WCG1PLV/ref=sr_1_2_sspa?crid=2XP9PQTJETKOD&keywords=esp32&qid=1671368136&sprefix=%2Caps%2C67&sr=8-2-spons&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUEyNE5XV1FaMzlTVlBNJmVuY3J5cHRlZElkPUEwMTk0MTg2UFc5V00xVUlVOTNGJmVuY3J5cHRlZEFkSWQ9QTAxNjQ1ODEyUERGT1FXM1hLNzFSJndpZGdldE5hbWU9c3BfYXRmJmFjdGlvbj1jbGlja1JlZGlyZWN0JmRvTm90TG9nQ2xpY2s9dHJ1ZQ&th=1 Hope this helps!

[@jeroldponko7168]

Very nice demonstration of Lissajous patterns on your oscilloscope. Not only pretty but useful in determining things like zero beat. Keep up the good work!

[@na5y]

Thank you Jerry. I have loved the lissajous patterns since I first saw them in high school many years ago. Interestingly (perhaps) the symbol for the government tv/radio broadcaster in Australia, ABC, uses a lissajous pattern as its logo en.wikipedia.org/wiki/Australian_Broadcasting_Corporation Bit of Aussie trivia for you ;)

[@R2AUK]

A very nice video, as always. Many thanks for sharing!

[@na5y]

Thank you Alex!

[@ploegmma]

Thank you, as always good valuable content

[@na5y]

Thank you Majodi!