I received the Si53301-based reference clock auto-switchover board I mentioned in previous posts. I assembled two boards. I've only tested one of them. See attached results and design files (the SA plots with max hold were run for approximately 1 hour each). I updated the design files to reflect minor changes I made (noted in the last page of the schematic). I'm happy with the results, so will continue to add the Si53301 to the receiver design in order to add the external reference clock with auto-switch over functionality. (allow an external GPSDO to be the reference for the freq synth/ADC/Audio/MCU clocks). The second board will have coax for all the outputs instead of BNC connectors. As I mentioned before, I'm planning on connecting the coax connections to the reference inputs of both frequency synths and the reference input of the MCU for testing before I commit to another spin of the receiver pcb. Will report on that later.
While waiting for the boards and parts, I was able to make a lot of progress on the firmware. I continue to be amazed by the capabilities of the STM32H743 part. I will expand on the details of the firmware at a later time, but I am very happy with the performance of the entire system.
Here is an example of the current list of built-in demodulators and decoders (no PC required, except for GNURadio driver). The P25P1 output is stellar. I will probably have to remove the calls to the DMR audio codec if I crowd-source it due to potential patent issues, but it does work quite well. Even with all the fir filters, poly-phase resampling / symbol sync, decoders, etc, there is still >180kB of ram left ( could be significantly more if needed) and only using something like 300kB for program flash. I'm definitely one of the people that think that the time is right for these higher powered MCU parts that have great peripherals built in (like the 16-bit ADC modules). With this kind of MCU, I was able to concentrate all the cost on the RF front-end all the way up to the ADCs. I know there isn't much interest in this thread so far, so I will keep the posting to a minimum unless significant progress is made.
List of stand-alone / built-in demod and decoders with audio output:
~$ ls decoders
Available SuperH+ built-in demod/decoders
------------------
FM Analog narrow/med/wide (mode fm)
AM Analog narrow/med/wide (mode am)
IQ 16-bit over UDP (mode iq) + GNURadio Driver
P25P1 Voice + Trunking Control Channel (mode p25)
DMR Voice + ConnectPlus Trunking Control Channel (mode dmr)
ADSB Mode-S - Console output (mode adsb)
ACARS - Console output (mode acars)
FLEX-4FSK-1600 - Console output (mode pagers, fm)
POCSAG 1200 - Console output (mode pagers, fm)
[edit] add note about time that max hold was run for each plot during testing
[edit] 2020-05-11 Due to the cost of this design combined with the entire lack of interest, I decided to open-source it. You can find the repository here:
https://github.com/tvelliott/superH_rev4