Chelmsford Amateur Radio Society
G0MWT, GX0MWT, GB5HF, GB5SM, GB100MWT, G100RSGB & GB95-2MT

CARS Meetings April - June 2018


Award for All

10th Jun 2018

Added May Antennas report, new date/venue for June Tabletop Sale


April Meeting
Tue 3-Apr-2018, 7.30-10pm
Oaklands Museum, Moulsham Street
"FreeDV - Digital Voice for HF
and other low SNR channels"

Matthew Phillips G6WPJ

A digital alternative to SSB on HF?

Since the beginning of 2017 the RSGB News (GB2RS) has been broadcast on 80m (~3.64 MHz) using FreeDV, an experimental digital mode intended to perform better than SSB voice in difficult radio environments.

Nearly 50 including several visitors were present for Matthews talk on FreeDV; what is it, how and why is it being developed by a worldwide community of radio amateurs and how amateurs can try it for themselves.

 


FreeDV Info and Spectrum plot was part of the background info presented to a keen audience

 
OFDM principles and a screenshot of the FreeDV software

 
Getting On the Air and Summary

Following the break Peter ran the raffle, and our speaker got his mug. Peter also gave a brief chat on antenna planning permission issues which is expected to lead to a fuller talk in due course.

 
Matthew receiving his Speakers Mug from Tony - and Peter drawing the raffle (Photos by John G8DET)

Useful Links:-

  • FreeDV - inc software download
  • Codec2 - inc audio samples



    May Meeting
    Tue 1-May-2018, 7.30-10pm
    Oaklands Museum, Moulsham Street
    "Unusual Antennas"
    by John Regnault G4SWX

    Guest speaker John Regnault G4SWX returned to CARS – on the topic of novel HF/VHF Antennas - a topic which attracted a full audience including soem professional visitors.


    Some of the attendees at this very popular talk

    John who is an EME enthusiast and the RSGB VHF Manager has previously given us talks on 'Building a Remotely Operated Station', 'Introducing Moonbounce', and 'Tricks with Coax'.

    This time he gave a thought provoking talk on some of the more unusual antenna configurations that are possible. In particular he took us back to the original pre-wr research by Yagi and Uda and highlighted soem overlooked aspects.

     
    From the original 1928 Paper - and Mr Yagi (1960s)

    In recent times the use of parasitic elements (not just a simple linear boom), assisted by modern modelling tools has come to the fore.

     
    1930 Uda 600 MHz (50cm wavelength) and a modern Digital TV 80 years later

     
    4Nec2 Software enabled John to analyse a whole series of permutations

     
    The Prototype Parasitic Broadside Array - and getting a speakers mug from Tony G4YTG

    The evening also featured our famous raffle, as well as refreshments. Following that Peter gave a brief overview of new equipment that the club had recently acquired as well as a demo of his workplace digital camera - which was fed into the projector to give a big display of the inside of a Pye Westminster.

     
    New club equipment and a workplace camera demo




    June Meeting
    Mon 18-Jun-2018, 7.30-10pm
    Danbury Village Hall, Main Road, CM3 4NQ
    "Table Top Sale"
    By CARS Members

    In order to assist with construction and recycling, the June meeting is the CARS Radio and Electronics Tabletop Sale, coordinated by Secretary Colin G0TRM.

    Items for sale can be from the whole range of radio, electronics, visual and audio, mechanical interest and more.


    To RETURN to the Meetings Page - Click Here


    To RETURN to the CARS Home Web Page - Click Here

  • ©Copyright CARS 2018