[Discuss-gnuradio] Eye Pattern visualization & Doppler-based perigee estimator (was: Re: Discuss-gnuradio Digest, Vol 194, Issue 3)

[CEL]

Hey Jim,

welcome to the community!
A quick hint beforehand: When you change the subject line (as the mail
you responded to suggested strongly), then people can more easily guess
whether they should be taking the time to read your mail. I was about
to skip it, and that would've been a bummer!

So, an eye pattern display is currently not available in GNU Radio
itself. We "only" have the QT GUI Time Sink, but that has no
"persistence" setting as of now. It's on our list of things to
implement for halfway feature-completeness. I'm optimistic we can come
up with a solution to that together. Can you talk a bit about your
specific use case? Is your GMSK reception already synchronized?

Regarding TCA: hm, I'm not overly familiar with the math involved, but
sounds like you'd observe the Doppler development over time to estimate
the slope of a set of tangents to the elliptical orbit of the satellite
and then solve for the time where orbit intersects with the main axis.

So: a bit of a math problem :) which could be relatively nicely solved
by first implementing a Doppler estimator (how definitely depends on
your system's characteristics and speed needs), and using the velocity
data that spits out either in post-processing of recorded speeds, or in
a python GNU Radio block that accumulates these velocity estimates and
estimates a TCA based on that.

Best regards,
Marcus

On Tue, 2018-12-04 at 10:15 -0700, Jim White wrote:
> Very new to GNURadio here...
> 
> Is there a block available that will display an eye pattern for
> digital 
> modulation for a GMSK or FM receiver?  I'm using a USRP B200 and
> have 
> built a couple of simple flows for it including a spectrum
> analyzer.  
> I'm looking for something that will show the eye pattern.
> 
> Also hoping for a block that will calculate the time of closest
> approach 
> from the Doppler curve after listening to and recording a satellite 
> pass.  This is about finding the TCA then matching it to calculated
> TCAs 
> provided by tracking programs. The objective is to match observed TCA
> to 
> TCAs from several sets of keps to match them up and determine which
> set 
> of keps is the satellite we are working with.
> 
> Jim
> 
> 
> On 12/4/2018 10:00 AM, address@hidden wrote:
> > Send Discuss-gnuradio mailing list submissions to
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> > Today's Topics:
> > 
> >     1. Fwd: [hamsci-swstation] A Little Fun with Digital RF
> >        (Michelle Thompson)
> >     2. Re: SDR for beginners (if not quite "dummies") (Bruce
> > Ferrell)
> >     3. Call for Participation FOSDEM & pre-FOSDEM Hackfest (Andrej
> > Rode)
> >     4. Looking for other users of the XTRX SDR (Markus Wirsing)
> >     5. Re: Looking for other users of the XTRX SDR (Matthias
> > Br?ndli)
> >     6. Re: Looking for other users of the XTRX SDR (Markus Wirsing)
> > 
> > 
> > -----------------------------------------------------------------
> > -----
> > 
> > Message: 1
> > Date: Mon, 3 Dec 2018 16:05:20 -0800
> > From: Michelle Thompson <address@hidden>
> > To: GNURadio Discussion List <address@hidden>
> > Subject: [Discuss-gnuradio] Fwd: [hamsci-swstation] A Little Fun
> > with
> >     Digital RF
> > Message-ID:
> >     <
> > address@hidden>
> > Content-Type: text/plain; charset="utf-8"
> > 
> > I enjoyed reading this writeup from a GNU Radio user, and wanted to
> > share
> > it.
> > 
> > -Michelle W5NYV
> > 
> > 
> > 
> > 
> > ---------- Forwarded message ---------
> > From: Greg KF5N <address@hidden>
> > Date: Sun, Dec 2, 2018 at 5:01 PM
> > Subject: [hamsci-swstation] A Little Fun with Digital RF
> > To: hamsci-swstation <address@hidden>
> > 
> > 
> > I had a great time at the TAPR Conference in Albuquerque, and I was
> > especially intrigued by the Space Weather discussion in the Sunday
> > seminar.
> > 
> > Nathaniel's description of "Digital RF" really got my attention,
> > and I
> > decided I wanted to experiment with it.
> > That took some doing, because I had to get a receiver and come up
> > to speed
> > on GNU Radio.
> > 
> > So about 3 months later playing with radios, computers, and
> > software here
> > is a report on my experiments:
> > 
> > https://github.com/Greg-R/explore_digital_rf/blob/master/docs/explore_digital_rf.pdf
> > 
> > The top of the repository is here:
> > 
> > https://github.com/Greg-R/explore_digital_rf
> > 
> > I want to do more experimenting using HF band
> > signals.  Unfortunately I am
> > in a hostile RF environment.
> > I've got my hands on a broadband loop antenna, so getting that
> > mounting and
> > working is next.
> > I hope I can pursue further experiments with the combination of GNU
> > Radio
> > and Digital RF.
> > Cool stuff!
> > 
> > 73 Greg KF5N
> > 
> 
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