Cardiff Microwave Roundtable

An SDR based Beacon Project

Third year students in Cardiff University’s Electronics Engineering program complete a course in which they design and build a project. This year two students chose to work on a 1.3 GHz beacon which the Cardiff University ARS hopes to install on campus. They’ll give a report on the progress and learning experience.

Designing a 1.3 GHz RF Power Amplifier

Shem Kalele

Shem is designing a 25 Watt, class AB amplifier using a Cree Gallium Nitride transistor. The design balances efficiency with linearity and gain.

Video Slides

A PI4 Beacon Modulator using SDR and GNU Radio

Ahmed Kamal

Ahmed has been implementing the PI4 beacon modulation protocol in Python and GNU Radio to be transmitted from an Analog Devices ADALM PLUTO SDR. Additionally a low power, band pass filter will supress any out of band spurious signals.

Video Slides

Cardiff RAYNET’s Mesh Network for Emergency Response

Dave Thomas MW0RUH

The Radio Amateur’s Emergency Network (RAYNET) organization in Cardiff has built a mesh network operating on the 2.4 GHz band. This provides a variety of communication and information services with no reliance on the Internet. Dave will talk about the network, services, and users.

Video Slides

Interlacing and HD for the DATV Express and LimeSDR

Do try this at home!

Phil Longhurst GW8BVI

Interlacing is a 1930’s technique which has a lot of benefits and is still in use today (1080i HD). But it is a pain to get it right and if you don’t the results look terrible! Using paid s/w (Vmix) and free s/w (OBS broadcaster) it can be done if you know how. 1080i HD looks fab and can be transmitted via a mere 1MS/s DVB-S2 with low-latency h.264 (not even the latest 4K HEVC) phys channel.

Video Slides

Tracking and Measuring Distances with LoRa at 2.4 GHz

Stuart Robinson GW7HPW

A brief introduction to using the Semtech 2.4 GHz LoRa devices for long distance high altitude balloon tracking and measurement of distance by time of flight of a packet exchange.


Transistor Load Lines at Home

Alex Alt

The Current-Voltage load line of a transitor tells you lots of information about how it will perform in an amplifier, but often aren’t included in datasheets. Learn what these useful measurements mean and how to take them using simple equipment. This talk shows how load lines can be used in amplifier design, starting with the measurements of IV curves and ending with an overview of how they can be used in high efficiency PAs.

Video Slides