[Ground-station] Operation PFB

[John Ackermann N8UR]

Hi Michelle --

I've done several PFB receivers in Gnuradio Companion.  They are all 
fairly narrow-band (FM or AM voice channels).  One is something like 115 
slots to channelize the AM broadcast band.  The flowgraphs are deeply 
ugly, but I'm happy to share them.

73,
John
----

On 11/20/18 11:56 AM, Michelle Thompson via Ground-Station wrote:
> We've had some recent successes with some very difficult pieces of the 
> project.
> 
> There is yet another one that needs some attention! :+D
> 
> I'm talking about the polyphase filter bank.
> 
> We have enough interest, enthusiasm, and competence to get this rolling 
> and succeed. Like LDPC, this technology has much wider application and 
> impact than just our project.
> 
> This filter bank is in the payload. We call it a channelizer. The 
> receive bandwidth is organized into channels by this filter bank. From 
> there, the communications are multiplexed into the time division 
> downlink DVB frames.
> 
> Polyphase filter bank is the exact right method to use, but it is going 
> to require a real team effort to get it working and demonstrated.
> 
> We have excellent MATLAB models for several different variants of 
> polyphase filter banks directly from fred harris. He wrote the book 
> about multirate processing and wants us to succeed. His contribution can 
> be found in the Polyphase Filter Bank repo 
> (https://github.com/phase4ground/polyphase-filter-bank).
> 
> We have a number of volunteers that want to help with this.
> 
> There is a polyphase filter bank in GNU Radio. It's used on our ground 
> station emulator flowgraphs. It's based on work by fred harris and Chris 
> Dick.
> 
> There was a polyphase filter bank in RFNoC, described at GRCon17.
> 
> There was an update and revision to the RFNoC work discussed at GRCon18. 
> The work appears to be ongoing. RFNoC ties you to USRPs, but the 
> increase in efficiency and speed put it into the Phase 4 Ground category.
> 
> Recently, we asked for a particular working repository from a particular 
> source to be released as open source, so we could use it as a codebase 
> and adapt it for Phase 4 Ground. That request was unfortunately denied. 
> This is not the only polyphase codebase that I've campaigned to get 
> donated, but it did feel like the most promising.
> 
> I know and appreciate how difficult it can be to dive in and start 
> working on a challenging and mathematically intimidating function like 
> multirate or polyphase.
> 
> If we want to succeed, then we need to either get a fast open source 
> implementation identified (or a proprietary one donated) that we can 
> adapt, or write one from scratch.
> 
> Here's the plan. We need eyeballs, and we need some risk takers.
> 
> 1) Go find all the open source polyphase implementations that are 
> currently out there. Report them here: 
> https://goo.gl/forms/BTIe81jb8746PqJ23
> 
> 2) Make and share a GNU Radio flowgraph that uses the polyphase filter 
> bank to receive several channels. Pick 2, or 4. Pick more if you're 
> ambitious. Use your RTL-SDR, your Lime, your HackRF, whatever you have. 
> How far did you get? What problems did you have? What's not clear in how 
> to use it? This is a pragmatic, operator-focused experiment in using a 
> very powerful technique. We need to know where it falls down and how far 
> we can push it with today's code.
> 
> 3) Write me if you want to participate but aren't currently one of the 
> members of our polyphase filter bank repository and I will add you.
> 
> It goes without saying but it's always better with. You do not have to 
> be an expert to participate, contribute, and learn. You just have to be 
> willing to accidentally become one while digging in.
> 
> I'm here to help make it fun and worthwhile. Want to get competent in 
> multirate and polyphase filter techniques? This is a wonderful 
> opportunity for that. It's cutting edge and highly marketable knowledge, 
> and is also a critical component for our radio system to work. Ask 
> questions, pick something, and publish it. The Polyphase Filter Bank 
> repository is where our work lives. Let's light it up.
> 
> _______________________________________________
> Ground-Station mailing list
> Ground-Station at lists.openresearch.institute
> http://lists.openresearch.institute/mailman/listinfo/ground-station
>