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Notes about the video meetings

Saturday 17 October 2020, 20:00 UTC

After some technical difficulties with Big Blue Button, we moved to Zoom and succeeded in doing the planned agenda:

  • Presentation of gr-RTTY-basics package
  • Audio loopback demo
  • Live Over-the-Air demo

The time (20:00 UTC) proved to be too late for participants East of Greenwich, so an earlier one was scheduled for 7 November.

Saturday 7 November 16:00 UTC

The meeting followed the agenda above. There was a minor audio difficulty with the loopback, but I proceeded to present the Over-the-Air demo successfully.

View the presentation on

Saturday 12 December 2020 16:00 UTC

Subject: Transmit / Receive switching and station control
Presenter: Gavin Jacobs VE7GSJ

  • Requirements for TX/RX switching
  • VE7GSJ Solution (hardware & GNURadio Companion)
  • Demo on 2m repeater


Thanks to Gavin for an excellent talk. It can be viewed at

16 January 2021 16:00 UTC

Subject: Using GRC to build radios: Make the flow graph work for you

Presenter: John Petrich W7FU


  • Getting started with GRC
  • Basic flow graph workspace organization
  • Flow graph details
  • Data flow problem solving
  • Practical odds and ends for real radios
  • Group discussion


Thank you to John for a very informative presentation. It can be seen at

27 February 2021 16:00 UTC

Subject: A Look at Project 25 (P25) Digital Radio

Presenter: Aaron Rossetto, NI

Agenda: In this presentation, I will introduce Project 25 digital radio, with a strong emphasis on its use in North American public safety trunked radio systems, and to describe experiments monitoring and decoding P25 traffic using GNU Radio code.

  • What is Project 25?
  • A brief introduction to trunked radio
  • Diving into the P25 protocol
    • Modulation
    • Packet framing and encapsulation
    • Packet types
  • GNU Radio and P25 decoding experiments

Presentation slides: Media:A_Look_at_Project_25_(P25)_Digital_Radio.pdf

Thank you to Aaron for an in-depth presentation. The video can be seen at

20 March 2021 16:00 UTC

Remember that Daylight Saving Time will have started in the U.S.

Subject: Ground Station Test Transceiver

Presenter: Ray Roberge WA1CYB


  • What is this Ground Station Test Transceiver ?
  • Architecture – Three Sections
    • Receiver flowgraph
    • Transmitter flowgraph
    • Telemetry flowgraph
  • GUI displayed with a ADALM Pluto SDR
  • Over the Air results as received on a ETTUS B205mini on SDR-Console software
  • Discussion on finer points of Packet telemetry
  • Same flowgraph modified for UHD, Ettus B205mini and why you need to modify it
  • QT display , GRC 3.8.2 / 3.8.0 minor issues noted
  • Discussion


See the video at

May 2021

date TBD

Subject: "Using Gnuradio during the 2017 Solar Eclipse"

Presenter: John Ackermann N8UR

26 June 2021

time TBD

In conjunction with HAMRADIOnline / SDRA / European Radio Days

Subject: "Understanding ZMQ Blocks"

Presenter: Barry Duggan KV4FV

Based on the Understanding ZMQ Blocks tutorial.


  • Types of ZMQ Blocks
  • Addressing
  • Using ZMQ Blocks
  • Terminal functions for flowgraphs

Also a separate video chat session for all interested hams!

10 July 2021 16:00 UTC

Subject: "Measurements with GR"

Presenter: Tom McDermott N5EG

20 - 24 September 2021

GRCon21 in Charlotte, North Carolina (we hope! Also virtual)

days and times TBD

  • Lightning Talk: "A Newbie's Guide to the GNU Radio Universe"
  • Talk: "Modular transmit / receive station control"
  • Hosted amateur radio breakout session Friday afternoon

Questions and Suggestions for future meetings


  • The Ham Radio chat room on Matrix is available for follow-up and continuing discussion.
    • server:
    • or via the Homeserver in a matrix app:
    • room:
  • Questions about meetings also can be sent to ""

Suggested topics

  • Transmit hardware to operate below 50 MHz.
  • amateur radio satellites
  • FreeDV
  • Contact ISS
  • EME - moon bounce communications
  • How to implement JS8, JS8-Call, and FT8 in GR
  • An in-depth walkthrough of GQRX
  • Spread-spectrum
  • video-chat troubleshooting session