On Sun, Jan 12, 2025 at 01:13:36AM +0000, Cameron Castillo via pacsat-dev wrote:
Hi Bill,
Interesting presentation! A couple notes:
On the FPGA design for the SDR, a significant amount of the work can be done via Xilinx IP. I think the team has the idea that most of the DSP and hardware would have to be built from scratch in verilog. For almost any design today, many people use the block diagram editor from Xilinx instead of writing their own verilog. Not only are these guaranteed to work but all the driver code is also available in their software platform (Vitis). I've looked into some of the DSP blocks they have available and the list is fairly comprehensive (IIR/FIR filters, FFTs, Freq. Synthesizer to name a few off the top of my head).
Yes, I'm aware of this. From what I can tell, the licensing is not open source on these. If that's so we can't use them on our platform. But maybe I'm wrong.
Second, I am planning on custom modulation, so those would have to be written in VHDL or Verilog. Not a show-stopper, though.
One of the other benefits is that many of Xilinx's products have hard integrated processors or have the ability to integrate soft processors (See Zynq and MicroBlaze respectively). The nice thing about these is that they support Linux development and bare-metal/RTOS configuration. We might even be able to remove the TMS570 and replace it with one of the multi-core devices. Perhaps we could have a system where Direwolf and the other processing functions are run on the same chip as the DSP. The downside to this is that I'm not sure how parallelable that would be (i.e. could we maintain four Rx channels).
If you are going to use something like a Zynq processor, why do you even need a DSP or an FPGA for this application? ;-) You could even get those fancy Zynq processors that have built-in RF subsystems. They just cost $2000 and need gobs of power. I don't know much about the MicroBlaze, how powerful it is or whatnot.
The big problem with these things is power. Zynq or Versal is right out. I'm looking to keep the entire power budget for everything outside of the PA to <1W. I think I can be successful if I play some tricks. I have no idea how much a MicroBlaze on an FPGA would use.
Also, there's a lot of functional safety things tied into the TMS570 processors. Things like lockstep processing, parity/ECC on everything, extended temperature, etc. The MicroBlaze can do lockstep, it appears, meaning that it can't be superscalar and it will be slow. I guess it says it's Harvard architecture. I don't know how it would compare to a Cortex-R5F.
I do a lot of work with Xilinx products and FPGAs at work. It's mostly for video functions, but I've found it pretty easy to understand the fundamentals of Vivado/Vitis in only a few months. With integrated peripherals like AXI and the IP blocks, it probably wouldn't take as long as everyone is thinking. I hardly ever touch verilog at work anymore...
I'm not against using an FPGA, but it would take some research. Do you have any idea of the power they would use?
As far as the amplifier project is coming, I'm back in the lab at work and want to get some more prototyping done with our actual amplifier. Does anyone on the team have extra stock of the transistor we're using for the Tx amplifier (ATF05MS004NT1)? I'd also like to get an inductor kit like this one https://www.amazon.com/First-Inductor-Assorted-1nH-270nH-42Valuesx50pcs/dp/B074QM4HNP as the one I have at work is all 0201s and I can't reliably solder it...
A book of inductors :-).
On that note, I'm happy to keep prototyping it if the team wants to go in that direction, but I think it'd be faster to go with a premade power amp. I've already created a schematic for a PA as a backup to the work I'm doing now. If we want something for Jim's test board, I could probably get something to at least prototype with a lot sooner even if we think we could do better with the discrete option. Just a suggestion.
Are you talking about a PA module as something that can be used on the satellite, or just something as a temporary solution to plug into Jim's board? And as I mentioned before, power is a big issue. I don't know much about these things, though.
Thanks,
-corey
Thanks,
Cameron Castillo
Cameron Castillo
KJ7ILB
*P*: (503) 752-8877
On Fri, Jan 10, 2025 at 8:47 AM Bill Reed [email protected] wrote:
This is a better URL...
https://github.com/AMSAT-NA/PacSatDocs/blob/main/SDR/MinyardSDR_1-9-2024.web...
-------- Forwarded Message -------- Subject: Last nights recording Date: Fri, 10 Jan 2025 09:31:07 -0600 From: Bill Reed [email protected] [email protected] To: Cameron Castillo [email protected] [email protected]
We discussed 2 things last night.
1: Start of SDR development to replace AX5043. Exciting stuff!
https://github.com/AMSAT-NA/PacSatDocs/SDR/MinyardSDR_1-9-2024
2: Discussion of 2025 budgets that haven't been approved yet. More to come....no video.
I would like to discuss your project with you at some point. Can it be prototyped on the new launchpad that Jim is working on?
Bill
pacsat-dev mailing list -- [email protected] View archives of this mailing list at https://mailman.amsat.org/hyperkitty/list/[email protected] To unsubscribe send an email to [email protected] Manage all of your AMSAT-NA mailing list preferences at https://mailman.amsat.org