ESP32 Based SDR Transmitter - Part 1 Audio Input
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- Опубликовано: 22 июл 2024
- In this new series I will be building and testing a low power SDR SSB Transmitter.
The schematics for the transmit mixer (work in progress) are here:
github.com/thaaraak/ESP32-Tay...
The code is here: (just PTT for the moment - more to come)
github.com/thaaraak/SDR-Trans...
Original video:
• Quadrature SSB Transmi...
Link for determining electret current
mynixworld.info/2017/09/01/sim...
0:00 Intro
1:21 I/Q based transmitter block diagram
2:54 Schematic walkthrough for Transmit mixer
6:35 Board populated with supply, ESP32 and ES8388
7:58 Phase Shift testing
10:06 Arduino software walkthrough
11:49 Adding a low pass filter in software and retesting
13:41 Walkthrough of microphone and connections
15:33 Microphone preamp circuit
16:44 Microphone preamp board
17:24 Preamp board populated
17:59 Testing the preamp board on the oscilloscope
19:47 Connecting the microphone/preamp to the transmit mixer
21:06 Looking at the 0/90 degree shifted audio from microphone to oscilloscope
22:33 Wrap up and next video description 
Наука
great explanation Ian, keep them coming 🎉🎉🎉🎉🎉🎉
Thank you Joe!
great video, i look forward to the next one
Thank you Khim!
Thanks, Ian!
Glad you enjoyed Alexandr!
Great Video , Nice , Waiting For Complete Transceiver..
Coming soon!
Great Job, I like it a lot!!
Thank you - should have the next in the series out soon
@@na5y Looking forward to watch it Ian!!! Thank you for all your excellent work!!1
Great amount of stuff to learn here - where did you pick up the EN8388 module? I only find the chips (probably clones) at the regular eastern suppliers...
The ES8388 module is from pcbartists and can be found here:
pcbartists.com/product/es8388-module/
I plan on using this combo also as it has an ESP32 and ES8388 in the one package:
www.aliexpress.us/item/3256803619642039.html?spm=a2g0o.productlist.0.0.23606c91rbHJPW&algo_pvid=ad742fa2-b0e8-4044-9159-54c56c1189cf&algo_exp_id=ad742fa2-b0e8-4044-9159-54c56c1189cf-0&pdp_ext_f=%7B%22sku_id%22%3A%2212000027228845836%22%7D&pdp_npi=2%40dis%21USD%213.86%213.74%21%21%21%21%21%402101e9d116708760879394577e95ee%2112000027228845836%21sea&curPageLogUid=zlZGgHlTEeWT
It doesn't have pin headers though or a USB interface
@@na5y Thanks a lot the ali one is a great find - I'm going to order 2 of them to follow along as you build - really learning a lot from your channel over the last few days! I'm not afraid of not having pins :)
IIRC the ESP32 processor is similar in "power" to the CortexM0+, so I would image that the dual core rp2040 processor (pico) should also be usable here.
Potentially - assuming CMSIS-DSP has an appropriately tuned FIR algorithm for that model. I think it does. Thank you for the comment!
I belive that rp2040 won't be able to hande the Hilbert transformer FIR as shown in this video. To handle the load, the ESP32 processor uses (clocks/sec) = 351taps x 4mac x 44.1kHz x 2channels = 124MHz, which is doable on 160MHs ESP core. Here are only 4 clocks are used to perform floating point multiply - accumulate (MAC) using assembler based DSP library, provided by the manufacturer. The rp2040 has neither floating point arithmetic, nor assembly-based DSP library, Even on faster M4 core, single MAC takes 7 clocks. So bottom line, it is unlikely to fit the rp2040 without compromises.
I haven't played around with the rp2040 at all I did do some playing around with DSP on the STM F7 uController. It was single core 160Mhz and it could do about 160 taps and there was little horsepower left over to do anything else. That was using CMSIS DSP and the F7 did have a math processor. Its a shame as I did like STM's tooling.
@@na5y just wonder, where do you get the time to play with electronics and to make a video. Great stuff!. Thank you for the detailed explanations and quality of the material.
Well being currently retired does help a bit ;)
Nice work Ian. Do you know what the value of the Microphone PGA gain in Register 9 ADC Control 1 is. It can be set for +24dB, just curious why you needed a microphone preamp. If you mention in the video my apology. Thanks Video is awesome can't wait for the next. 73
I have honestly never tried that. Would be great to not have to have the preamp. You'd still have to have power to the electret of course. I might give that a try - thanks for the suggestion and comment!
Just checked in es8388.cpp its hardcoded to 0x11 - +3dB per channel
@@na5y Yes of course you still need to bias the microphone. I found a quick way to change the PGA is in ES8388.cpp in the ".init" method. The data sheet recommends that you use balance mode but just for a test should be fine. Thanks again Ian
🔥👍
Thanks Alex!
G'day Alex!
@@Paul_VK3HN 👋