Chelmsford Amateur Radio Society
G0MWT, GX0MWT, GB5HF, GB100MWT & GB100MZX

CARS Meetings: Jan - March 2021




January Meeting
Tuesday 5th Jan 2021, 7:30pm
Online by Zoom
"Data Networks and IoT"
Phil Pearson G0UIB

For our first talk of the New Year, we welcomed back Phil Pearson G0UIB who is an expert on 'Data Networks using Internet of Things (IoT) Devices'. This is all about using cheap devices designed to work with low power sensors etc.

For small automated devices, VHF/UHF voice is neither suitable or an efficient method for efficient message transfer, especially if there are multiple relays or/and repeaters.

Traditional repeaters and networking systems all have costs which limit availability, given that they also require careful locating and planning. A simple low cost approach based on a simple need of 140 character text messages and maximised battery life is still really useful for many applciations without the need for realtime megabit Wi-Fi.

The Internet of Things (IoT) is the idea that devices will be linked to the internet to transfer data automatically. Many of these are in this lower data rate and low power category. Typical frequencies used include 433 and 868 MHz, lower than Wi-Fi, so they can more easily penetrate building walls.

One of the emerging standards for this is LoRa which is also being adapted for some amateur radio because as it has a rather attractive characteristic of being Long Range over many kilometres despite it being lower power UHF. It uses a cleaver designed chirp waveform to spread the signal on transmission, with a FFT on receive to achieve processing gain and eliminate much of the noise.


LoRA: 40km is eminently achievable with milliwatts - longer range with far lower power than Marconi's CW test

Imagine something you leave in a field and it tells you the soil moisture once a day, so you want it to work on very low power batteries/solar. To make a digital network which can connect several nodes together, the sensor nodes send data over multiple hops from one end to the other, all cheap to build and low power. As you cannot always rely on line line of sight, an adhoc network that relays the message via the best avilable route is needed to make it thru instead.

Phil's work has been to enhance adhoc mesh networking tracking, merging with GPS info etc for pure radio mesh (without being dependent on the Internet, as used by LoRAWAN).

 
433 MHz LoRa Modules - and how they can be set up auto-mesh to route around an obstacle

Our thanks to Phil G0UIB for an insight into the latest we can dabble with.


A young Phil as Novice 2E1AOJ (middle of back row), from RadCom August-1992

Further reading:-

  • Wiki - en.wikipedia.org/wiki/LoRa
  • LoRA - lora-alliance.org



    February Meeting
    Tue 2-Feb-2021, 7.30pm
    Online by Zoom
    "Forewarned is Forearmed"
    By Nigel Newman M0ICH

    For February we welcome Nigel Newman M0ICH for an online Zoom talk. Up until the 1980’s the Royal Observer Corps (ROC) underground bunkers were the only means of coordinating the response to a nuclear attack.

    Essex CW member and former ROC volunteer (c1976) Nigel M0ICH, will give an online presentation to CARS describing the equipment used and the role of the radio in the event of an apocalypse.

    The title ‘Forewarned is Forearmed’…. is the motto of the ROC.

    Zoom:

  • Meeting ID: 837 3051 3024
  • Passcode: 996469



    March Meeting
    Tue 2-Mar-2021, 7.30pm
    Online by Zoom
    "Behind the Scenes"
    By John O’Connell M0JOC

    Our Exam Secretary/Training coordinator John O’Connell M0JOC talks about his role as Tour Manager for a professional 12-piece international touring band – event planning, onstage requirements including wireless connectivity and experience providing technical support for live performances/concerts including photos and video clips.

    Also, a lighthearted look at the old adage “what goes on tour stays on tour …..”, from an open air concert in front of a submarine in Montenegro, an underground cave in Hungary, The Jazz cafe, O2 Arena and Ronnie Scott’s, to The Albert Hall.

    Zoom:

  • Meeting ID: 817 9185 9988
  • Passcode: 667437


    To RETURN to the Meetings Page - Click Here


    To RETURN to the CARS Home Web Page - Click Here

  • ©Copyright CARS