Table of Contents

MeshCore ‒ Part 2

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This is the second part of the MeshCore Guide. See the first part to get started.

Repeaters

As mentioned in the first part, repeaters are used to extend the range of companions. With radios, the range roughly depends on three factors:

Let's highlight here that it doesn't make sense to talk about the range of one radio. For example, I might be able to reach Bob at a maximum distance of 1 km, while reaching Alice 2 km away. That's because Alice might have a better antenna or be higher up than Bob. If one person improves their antenna, height, or line of sight, it helps everyone communicating with them.

That's not so with power. If Bob increases his power, everyone will hear him better, but that won't help him hear anyone else better. It's like if two people on opposite sides of a football field tried to talk to each other: one with a megaphone, and one without.

As a rule of thumb, everyone should use roughly the same power, and focus on improving their antenna, line of sight, and height.

With that in mind, to be effective, a repeater should have a good antenna, be as high as possible, and have a clear line of sight to other repeaters and companions.

Equipment

Flashing the Firmware

Installing a Bootloader

This step is optional, but it allows future updates to be performed over-the-air (OTA) via Bluetooth instead of wired via USB. It is not required for (or compatible with) ESP32 devices like the Heltec V or T beam.

If you already have MeshCore installed (but not the bootloader), download your current settings:

Download the bootloader:

Copy the bootloader over to your device:

Flashing the Firmware

Flash the MeshCore Firmware:

Re-upload your settings:

Updating the Firmware OTA

Set up the Over-the-Air (OTA) update app (first time only):

Perform an OTA update:

See Scott Baker's article for more information.

More Advanced: Sensors

Appendix

About Power

The transmit power of radios is often measured in watts (W). For example, in Canada, FRS radios are limited to 0.5W for channels 8‒14, and 2W for the channels 1‒7 and 15‒22.1). Handheld ham radios can typically transmit up to 5W, mobile VHF/UHF radio up to 50W, and HF radios can go up to 100W without an amplifier, and 1000W with an amplifier.

The MeshCore uses dBm instead of W as a unit of power.

Very briefly, a decibel (dB) is a logarithmic scale used to compare two quantities:

A is 10 dB over B ⇔ A is 10 times bigger than B
A is 20 dB over B ⇔ A is 100 times bigger than B
A is 30 dB over B ⇔ A is 1000 times bigger than B

Do you see the pattern? If not, you can read more about the dB scale here.

A dBm is “dB over 1 mW (milliwatt)”. In other words, it tells you how many times more powerful than 1 mW your power is.

Here are a few values:

1 dBm ≈ 1.3 mW
2 dBm ≈ 1.6 mW
3 dBm ≈ 2 mW
4 dBm ≈ 2.5 mW
5 dBm ≈ 3.2 mW
6 dBm ≈ 4 mW
...
10 dBm = 10 mW
20 dBm = 100 mW
30 dBm = 1 W

Here's how to convert from dBm to mW. Let's use 22 dBm as an example (which is the maximum power of the Wio Tracker L1 Pro device):

Converting from mW to dBm is a little harder because we need to use the Log function. Let's convert 2.5 W to dBm.

Sunshine Coast Repeater Project

meshcore_repeaters.jpg The MeshCore app has a very handy Antenna Coverage tool to model line-of-sight coverage. You can use it without having a device:

To import the locations that we've modelled:

Copyright

This document is licensed under CC BY-SA 4.0 International. The original can be found at https://scarcs/meshcore/home

Footnotes

1)
https://www.fleetwooddp.com/pages/frs-gmrs-frequencies