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Notes about the video meetings

Saturday 17 October 2020, 20:00 UTC

Subject: Simulation example of FSK

Presenter: Barry Duggan KV4FV

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

The time (20:00 UTC) proved to be too late for participants East of Greenwich, and we did not capture a recording, so a repeat 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

8 May 2021 16:00 UTC

Subject: "Using Gnuradio during the 2017 Solar Eclipse"

Presenter: John Ackermann N8UR

The total solar eclipse in August, 2017, was the first opportunity for the "HamSci" community to get crowdsourced ionospheric data, looking for propagation changes as the eclipse occurred. There were several HamSci activities that weekend, including an Eclipse QSO Party. A number of hams monitored the bands looking for changes in frequency or amplitude as local totality approached and went.

I used SDRs and Gnuradio from my location in northern Michigan to record the entire 80, 40, 30, and 20 meter bands, as well as the entire AM broadcast band, for 8 hours. The result was nearly 1 TB of data.

I'll show the equipment configuration, some of the Gnuradio tools used both to capture and post-process the data, and some results of the experiment.

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.

Agenda: Media:Understanding_ZMQ_Blocks.pdf

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