[Ground-station] Operation PFB
John Ackermann N8UR
jra at febo.com
Mon Jan 14 17:38:27 EST 2019
I'm on the road for a day or two but will dig them out and get them to you.
On 1/14/19 5:32 PM, Michelle Thompson wrote:
> Hi John!
> Could you share them? I'm sure they have a special inner beauty that we
> all know and love!
> -Michelle W5NYV
> On Tue, Nov 20, 2018 at 10:06 AM John Ackermann N8UR via Ground-Station
> <ground-station at lists.openresearch.institute> wrote:
> 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
> slots to channelize the AM broadcast band. The flowgraphs are deeply
> ugly, but I'm happy to share them.
> 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
> > 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.
> > 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
> > 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
> > 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
> > 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
> > Recently, we asked for a particular working repository from a
> > source to be released as open source, so we could use it as a
> > and adapt it for Phase 4 Ground. That request was unfortunately
> > 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
> > 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
> > 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
> > 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
> > 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.
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