Repeaters are the basis of the MeshCore network. Repeaters enable Companions to communicate and thus bridge long distances with up to 64 hops.

Most repeaters are solar-powered. This makes them self-sufficient and accessible around the clock, as long as the batteries are sufficiently charged. The construction proposal described is only intended to give an idea of what is needed to participate in the MeshCore network using simple means.

Only a few components are needed to build your own repeater:

• a sufficiently sized solar panel, approx. 5-8W
  (e.g. https://www.action.com/de-de/p/3214527/re-load-solarmodul/)
• a node ideally based on an nRF chip, e.g., XIAO nRF52840 & Wio-SX1262 Kit
  (e.g. https://de.aliexpress.com/item/1005008760784706.html)
• a CN3791-based MPPT solar charging module
  (e.g. https://de.aliexpress.com/item/1005007355378997.html)
• 18650 LiPo Batteries 3,7V / 3500mAh
  (e.g. https://de.aliexpress.com/item/32810182330.html)
• suitable housing
  (e.g. IP65 plastic housing https://www.amazon.de/dp/B0F3D7TDMT or integrated into a birdhouse)
• Mounting bracket
  (e.g. https://www.obi.de/p/8023822/alberts-duravis-flachstahl-betonanker-schwarzdiamant-duplexbesch-205-x-40-x)
• small items such as screws and cable glands

These components add up to a total of approximately €30.

1. Prepare the solar panel

To connect the solar panel to the MPPT charge controller, the USB part on the solar panel must be removed. To do this, remove the adhesive plastic housing and unsolder the two solder tabs on the panel from the USB board.

2. Connect the components

The solar panel is now connected to one of the two solar inputs with the MPPT charge controller. The batteries and the XIAO nRF52840 must also be connected to the MPPT charge controller. The outputs for the batteries and the output to the consumer, i.e., the XIAO nRF52840, are electrically connected to each other. So it doesn't matter what you connect where.

3. Housing and assembly

A hole is drilled in the upper third of the housing through which the connecting cables of the solar panel are fed. The holder also has a similar feed-through. The holder and the housing shell are then glued to the solar panel with silicone. This ensures sufficient sealing. Once the silicone has dried, the antenna is attached to the bracket and the antenna cable is fed through a feed-through at the bottom of the housing. Now the components are connected electrically. After flashing the XIAO nRF52840, the housing can be screwed shut.

I used a concrete anchor from the hardware store for just under €4 as a holder for the repeater. This allows the repeater to be attached to a tree, house, or mast.

These are the additional settings to the above-mentioned “General Settings,” which are recommended for use on all repeaters.

Admin password

It is recommended that you change the default password “password” to a secure personal password to prevent third parties from making changes to the repeater.

Guest password

The guest password can be left blank. This allows other users to view the repeater's basic statistics, telemetry data, and neighbors without being able to change any settings.

Advert-Intervall

With the following two settings, repeaters can automatically make themselves known.

Zero-Hop-Advert

0 – Disable, as this is only a local advertisement that is essentially unnecessary. The Flood Advert setting below also covers zero-hop advertisements.

Flood-Advert

48 – Set this value to 48 hours to avoid unnecessary traffic. Companion nodes do not need to know about repeaters in order to use them, so it is not really important that repeaters send many adverts.

RX delay

0.0 – This is currently the best setting recommended by the MeshCore community.

TX delay

0.5 – Das ist die derzeit von der MeshCore-Community empfohlene beste Einstellung.

Time

It is very important for MeshCore that the repeaters are set to the correct time, as otherwise problems with the adverts may occur. The easiest way is to use “remote management” via the Android or iOS app with a companion node. For RAK-based repeater nodes, it is recommended to add the RTC module.

Map

For repeaters, it is strongly recommended to add them to the official MeshCore map. This can be done directly via the MeshCore Android or iOS app.