LoRa

admin · December 10, 2022, 12:29am

Introduction

LoRa is one of the three radio technologies used in Team Compute Activity Markers.

LoRa is particularly useful in areas where there is no Cellular or WiFi or Bluetooth signals e.g. in remote rural areas or during disasters in urban areas.

Radio	Distance	Power	Speed	Approx. Meters
Bluetooth	low	medium	medium	10 m
WiFi	medium	high	high	100 m
LoRa	high	low	low	1000 m

LoRa is a sub-1GHz radio technology was designed for long range communications.

Note LoRa does NOT perform well in some high density urban use cases.

Although we are only experimenting with the LoRa protocol but there are other long range network protocols (e.g. thread, wise, wi-sun, sigfox, ts-unb, zigbee, z-wave etc.) as well as the IEEE ones (e.g. 802.11ah, 802.11af, 802.22 etc.) available also.

In rural areas, LoRa can have reach, cost and privacy advantages over cellular carrier IoT offerings like LTE-M (medium throughput usage) and NB-IoT (low throughout usage), enables citizens to communicate wirelessly over long range WITHOUT going through traditional 3G, 4G, 5G cellular mobile networks.

Depending on deployment parameters, a 10 km range outdoors (with direct line of sight) is possible. We are adding mesh technologies, so signals can be relayed to extend that range further.

Protocols

LoRa has a number of communication protocols :

Meshtastic - decentralised use cases (supported)
LoRaWAN - centralised use cases (legacy support only)

If you are joining Team Compute after 2024, please use Meshtastic instead of LoRaWAN.

Realtime maps of some Meshtastic nodes worldwide:

The Mestastic device must have WiFi so it can input CLI commands and output MQTT data.

Network Configuration | Meshtastic

Applications

Initially we are using LoRa as Activity Markers, but will expand it to transport messages, sensor data etc. progressively.

admin · December 10, 2022, 9:04pm

Meshtastic Firmware

Meshtastic Guidelines

If a device does not support concurrent bluetooth and wifi, then wifi should be used.
Use the latest release if possible.

Meshtastic Presets

Radio Preset	Data-Rate	SF / Symbols	Coding Rate	Bandwidth	Link Budget
Short Turbo	21.88 kbps	7 / 128	4/5	500 kHz	140dB
Short Fast	10.94 kbps	7 / 128	4/5	250 kHz	143dB
Short Slow	6.25 kbps	8 / 256	4/5	250 kHz	145.5dB
Medium Fast	3.52 kbps	9 / 512	4/5	250 kHz	148dB
Medium Slow	1.95 kbps	10 / 1024	4/5	250 kHz	150.5dB
Long Fast	1.07 kbps	11 / 2048	4/5	250 kHz	153dB
Long Moderate	0.34 kbps	11 / 2048	4/8	125 kHz	156dB
Long Slow	0.18 kbps	12 / 4096	4/8	125 kHz	158.5dB

Notes:

Default Meshtastic Radio Preset is Long Fast we default to Long Slow
SF means Spreading Factor - each step up in SF doubles the airtime to transmit.
Coding Rate - how much redundancy we encode to resist noise (4/8 mean 2x overhead).
Bandwidth - how much of radio spectrum we use.
Link Budget - assumes transmit power 22dBm and antenna 0dB gain.

Meshtastic Spectrum

Frequency Slot Calculator

Radio Settings | Meshtastic

High Frequency LoRa Example

Using the calculator we got:

Region	Preset	Slots	Default	Start	End
ANZ	Long Fast	52	20	915.1250	927.8750
ANZ	Long Slow	104	27	915.0625	927.9375
US	Long Fast	104	20	902.1250	927.8750
US	Long Slow	208	27	902.0625	927.9375

Australia uses LoRa high frequency bands that are slightly above the USA bands.

Low Frequency LoRa Example

Using the calculator we got:

Region	Preset	Slots	Default	Start	End
ANZ	Long Fast	6	6	433.1750	434.4250
ANZ	Long Slow	13	1	433.1125	434.6125
CN	Long Fast	160	36	470.1250	509.8750
CN	Long Slow	320	187	470.0625	509.9375

Australia uses LoRa low frequency bands that are slightly below the China bands.

Meshtastic HAM

Meshtastic has a set-ham option to for used by Amateur Radio operators. They can use their license to boost Lora power and range in some countries.

Meshtastic References

admin · December 10, 2022, 9:06pm

Meshtastic Hardware

Meshtastic supports a number of hardware devices:

Devices | Supported Hardware Overview | Meshtastic

LoRa Chipset

A number of LoRa chipsets are used in meshtastic hardware, two of the most popular are SX1262 and SX1276, of the two SX1262 is preferred over SX1276

SX1262 range can be increased by running
meshtastic --set lora.sx126x_rx_boosted_gain true
to increase gain with a small increase in power consumption.

External Antennas

For mobile applications the bundled antennas can be used, but for fixed location deployments it is best to use external antennas instead.

1. Heltec LoRa 32 v3

A low-cost LoRa device WITH display is the Heltec LoRa 32 v3.

v3 Bundled Antennas

Hletec v3 can come with 3 types of antennas:

is supposed to be of poor quality
is supposed to be better but will not fit into the cheap green case
is supposed to have good quality and fits into cheap green case

v3 Hacks

newer v3 antenna is better
https://www.youtube.com/watch?v=znQAsYs12y8
use v3 as spectrum analyzer
https://www.youtube.com/watch?v=oI0ekb_Ud60

2. Seeed Studio XIAO ESP32S3

A low-cost LoRa device WITHOUT display is the LoRa daughter board (WIO SX1262) plugged into a WiFi motherboard (XIAO ESP32S3).

Note the Meshtastic link above use the WIO SX1262 (which is correct) but it talks about using it with the XIAO nRF52840 (which does NOT have WiFi), we need a motherboard that supports WiFi e.g. XIAO ESP32S3.

admin · December 23, 2022, 9:47pm

Meshtastic Software

Meshtastic has a wide range of software:

Software | Meshtastic

Web Client

GitHub - meshtastic/web: Meshtastic Web Client/JS Monorepo

Using HTTP to connect is preferred:

Web Client Overview | Meshtastic

Web Flasher

admin · December 29, 2022, 3:41am

External Antenna

Many low-cost yet high-performance external antennas are available at LoRa frequencies.

For 915MHz the following is recommended for beginners:

TX915-JKC-20 has 5 antennas
https://www.cdebyte.com/products/TX915-JKD-20/1

Note

these are dipoles, so performance tend to be better than monopoles.

1. IPX to SMA cable

Connectors

SMA can be MALE or FEMALE
IPX has many other names IPEX-1 or U.FL

There are normally 3 cable sizes:

0.81mm
1.13mm
1.78mm (also called RG178 )

Please get thicker cable e.g. RG178 if possible.

C934-001_datasheet.pdf (2.2 MB)

Make sure to get the correct MALE or FEMALE version of the SMA connector for your external antenna.

2. Tigertail

If you have a monopole antenna, sometimes you can increase its range with a "tigertail" hack to make it into a dipole.

Building the Tiger Tail Antenna - Paratus Radio

admin · December 29, 2022, 4:37am

LoRaWAN

Due to its centralised design, LoRaWAN is NOT our preferred LoRa network protocol, it still has some installed based worldwide, so we do supported it in special cases. In all other cases, Meshtastic should be used instead.

1. LoRaWAN Australia

Australian government has allocated 915 MHz to 928 MHz for use as an ISM band.

When buying LoRa equipment for use with LoRaWAN in Australia, please get the 915 MHz version. Note 923 MHz is also legal to use in Australia and LoRaWAN has been deployed using 923 MHz in Australia but we would like to keep everyone on 915 Mhz for now.

AU915-928

64 channels total
30 dBM EIRP
Each of the 64 channels is 0.2 MHz wide (1st channel centred on 915.2MHz and 64th channel centred on 927.8 MHz)

AS920-923 / AS923-925

16 channels total
16 dBM EIRP

2. LoRaWAN Server

The following LoRaWAN servers have been tested to work with Team Compute:

3. LoRaWAN Security

Despite LoRaWAN's best intentions, defining end-to-end security centrally that covers device, network and application layers can be problematic - any weakness affects every device and application on the network.

Use Meshtastic instead of LoRaWAN if you do not need backward compatibility.