Dorking & District Radio Society

Recent Meetings and Events

History of Emergency Communications

26 October 2021

Our visiting speaker Steve Shorey gave a very informative illustrated talk on the history of communications in the police and other emergency services. Steve started right back before formal police forces, through bobbies on the beat with rattles and whistles, wired telegraphy and finally the start of radio. That heralded an exponential growth in need for communication to establish an effective police force and keep front line officers in contact, pushing the boundaries of the emerging techologies and increasing frequencies in use. Steve discussed the challenges of more recent large scale events such as the London Olympics, and described some future developments still in the pipeline. He spoke from real experience, having worked in the Metropolitan Police.

Introduction to CW Operating

29 September 2021

Tim, Mike and Colin explained why and how to start using morse code in an amateur radio context, sharing their own experiences of learning and operating. Practical activities included use of various key types, listening on air with various aids and self-teaching software. A summary of the presentation notes with links is now available.

Devil's Dyke Expedition

24 August 2021

Our annual outdoor operating event on the South Downs started earlier in the afternoon this year, to make best use of the daylight. Operators using HF and VHF enjoyed a productive few hours setting up equipment, making contacts and chatting to interested members of the public. A meal at the local restaurant rounded off the evening.

Summer Social

27 July 2021

The traditional fish and chips supper was held a month earlier than usual this year to take advantage of the warmer weather, as we needed to be outside to fit with the government restrictions.

Outdoor Operating Evening

22 June 2021

We met at Denbies Hillside, a beauty spot on Ranmore Common on top of the North Downs, to set up portable stations and enjoy chatting on air and with passing visitors. We were also in the company of the local running club, on a commemorative outing across the valley to Leith Hill Tower and back.

Beacon Hunting

25 May 2021

Club members and visitors gathered at Headley Heath for a fun evening outdoors, practising radio direction finding. Using 3-element "tape measure" antennas and simple receivers provided by Denis Noe, we set about locating small transmitters hidden among the trees.

Spectrum Analyser Project

27 April 2021

David Wilde demonstrated his DIY spectrum analyser, which he designed and built around a standard digital processing chip. He explained the process to get a multi-layer PCB manufactured, the use of a surface acoustic wave filter, digital filtering to sample the incoming signal by frequency, and a browser interface for user interaction. He also described some commercially available spectrum analysers.

Orbital to Linear Angular Momentum

23 March 2021

Tim Brown and Ben Allen jointly explained how multiple antennas with suitable phasing delays could be used to create radiation with "orbital momentum", rotating around as they travel along. Using different rates and directions of rotation, multiple channels can be created on the same frequency, increasing the total bandwidth. An analoguous approach using antennas spaced linearly, alongside a railway track for example, could be used to enable broadband communication with moving trains, without the need for intrusive masts in rural areas. This was demonstrated using models and amateur radio equipment.

Propagation Prediction using the Chilton Ionosonde

23 February 2021

Philip Miller Tate gave some background information to the ionosonde at Chilton, OxfordShire, and showed us various examples of the ionograms it produces. He explained the structure and nature of the ionosphere, and how to interpret the ionograms to deduce likely propagation conditions.

Mr Marconi and his Marvellous Invention

26 January 2021

Dr Liz Bruton, a curator at the Science Museum, told the story of how early radio technology progressed from a short range demonstration on Salisbury Plain; to the first live reporting from a ship of a yacht race in Ireland; and to enabling the Titanic to call for help and thus save hundreds of lives. That fateful night was documented minute by minute in the telegraphic communications with other ships, which Liz poignantly described.