Modern amateur radio is changing rapidly, and Software Defined Radio (SDR) is at the centre of that change. Many amateurs already own an SDR — or use one indirectly — but few have had the chance to understand how it actually works or why it feels so different from traditional radios.

This upcoming lecture will provide a plain‑language introduction to SDR, aimed specifically at amateur radio operators, not engineers or programmers.

Block diagram of a typical SDR Radio system (courtesy https://www.rfglobalnet.com)

Rather than focusing on mathematics or theory, the talk will explain SDR concepts using familiar radio ideas: receivers, mixers, filters, IF stages, and transmitters — and show how these functions are now being done in software instead of hardware.

Topics will include:

• What “software defined” really means in a radio
• Why SDRs can see so much spectrum at once
• The role of analogue‑to‑digital converters and why bit‑depth matters
• Why some SDRs are better at weak‑signal work than others
• How modern SDRs replace IF strips with digital processing
• What limits SDR transmit power and why filtering still matters
• How SDRs are used by amateurs, researchers, and modern networks

The lecture will also touch on GNU Radio, the most widely used SDR software framework, explaining what it does and why it has become so important — without requiring any programming knowledge.

Whether you are:

• Curious about SDR but unsure where to start
• Using an SDR “black box” and want to understand what’s inside
• Interested in digital modes, weak‑signal work, or experimentation
• Wondering how modern radios differ from classic superhets

…this session is designed to demystify SDR and connect it back to the radio principles amateurs already know.

No prior SDR experience is required — just an interest in radio.

So when are where is this event? AREG meets at the Fulham Community Centre, off Phelps Court, in Fulham, Adelaide. Doors open at 7.00pm, Friday 17th April.

This month the meeting will begin with a short Special General Meeting to address a minor change to the group’s constitution, followed by the presentation which will likely start around 7.45pm.

For our regional members, the meeting will, as usual, also be interactively streamed via Zoom. If you are a regional amateur and are interested in finding out a little more about AREG, guest passes are available to our Zoom meetings on request. Please contact our secretary – via vk5arg@areg.org.au