GB3TV Maintenance and a new Meshcore node

Today Phil G8XTW and Matt G4IYT visited the GB3TV TV repeater site to perform a number of tasks. First on the list was to work out why the repeater had suddenly died. Fortunately it was a simple mains power issue which was easily rectified, and once the repeater had started we received reports that it was operating normally.

WiFi

The second job was to conduct a WiFi site survey and test the 2.4GHz and 5GHz bands to see if we could successfully connect to a local, friendly WiFi network. Tests on 5GHz were unsuccessful, however with careful placement of the beam we were able to achieve 65MB/s both ways on 2.4GHz.

The various Raspberry Pis operating the box had previously struggled to access the WiFi due to being in a metal box away from the main access point. The new AP is outside the box and provides a Ethernet connection to a hub inside the box. This enables the repeater to be controlled remotely over the internet. We are also planning to configure the repeater to accept streams from the internet. This would enable those without transmitting equipment to use the repeater using just a laptop with a camera and a stream key.

70cm Input Improvements

While the lid was off the box, a filter and preamp were fitted on the 70cm input which we had found to be a little deaf following it’s addition last summer. Early testing from Arthur G4CPE indicates that this has improved 70cm reception by approximately 14dB! The filter is a small interdigital type, the amplifier a PGA-103+ in enclosed in a blue aluminum box which seems to be ubitquitous on various far eastern marketplaces.

The GB3TV innards, with 70cm filter & preamp assembly visible at the bottom

Meshcore Repeater

The final task to install a Meshcore repeater on 868MHz which has been a pet project of Matt G4IYT. The node identifies as “DDRC Omni”. This installation has successfully bridged the large southern mesh covering Hertfordshire and as far south as Caterham, with a smaller but very active mesh covering Milton Keynes and Northamptonshire.

Meshcore is an alternative to the popular Meshtastic project. Both use LoRaWAN devices for off-grid messaging and teletry. Meshcore is a lighter protocol which appears to be more stable over longer multi-hop paths.

A map showing DDRC Omni and some of the surrounding mesh nodes.