Define hardware link between GS and LPS

[wanysteus]

Requirements :

• Range over 10m (~100m line of sight is good)
• Bi-directional
• Easy to integrate using standard Arduino boards
• As little RF work to do as possible (antennas, shielding, ...)
• High bitrate is not mandatory

[wanysteus]

Quick overview of long range transceivers

Summary

	nRF24L01+	RFM69HCW	RFM9XW	SX1276/7/8/9
Type	FSK	FSK	LoRa	LoRa
Freq.	2.4 GHz	433/868/915 MHz	433/868/915 MHz	433/868/915 MHz
Valim	3.3V	3.3V	3.3V	3.3V
Vlogic	3.3V (5V ok)	3.3V	3.3V	3.3V
Protocol	SPI	SPI	SPI	SPI
Lib	RF24 RadioHead	RFM69 RadioHead	RadioHead	RadioHead
Link Budget		140 dB	164 dB	168 dB
Antenna	Trace antenna	DIY (1/4 wavelength)	DIY (1/4 wavelength)	Spring
Datasheet	Here	RFM69HCW-V1.1.pdf	RFM96W-V2.0.pdf	Here
Buy module		Ebay (4$ + 10\$) LowPowerLab (6\$ + 15\$)	Ebay (6$ +10\$) Banggood (7\$ + 0\$) LowPowerLab (12\$ + 15\$)	Makerfabs
Buy breakout	Sparkfun (21$)	Adafruit (10$)	Adafruit (20$)	Makerfab (5$)
Example	RandomNerdTutorials	Adafruit	Adafruit	CircuitDigest

Prices after "+" are shipping costs. Shipping cost is unknown were there is no "+"

Notes

LoRa modules should get > 1 km range (line of sight) with a basic antenna.

Many counterfeit nRF24L01 on the market. Random performances.

Lots of information about RFM69/RFM9X. In particular lowpowerlab.com. Looks very reliable. Some modules look not genuine on ebay

Not much data about SX127X.

I suggest using a 3.3V board to use the transceivers. Tensy 3.2 are good but expensive. Another solution would be to use level shifters

[wanysteus]

Okej this topic has been open long enough. The conclusion so far seems to be:

• We go for LoRa
• We go cheap
• We go reliable

Having 4 LoRa modules is good if we want to have one pair for the electronics team (for development and tests) and one pair for the propulsion team (for them to test their stuff). The 2 excess modules could also be used as spare in case of failure at the wrong time

The chosen parts are:

• [4x] Arduino nano boards & USB cables & breadboards
• [4x] banggood 70kr 1pc RFM96W (433MHz) because it is available for cheap on banggood
• [1x] banggood 25kr 5pcs AMS1117 step down converters to power the RFM96W
• [3x] banggood 28kr 5pcs Bi-directional Logic Level Converter (two channels, 6 channels/LoRa module needed)

Total ~389kr

Single-core wire will also be needed to connect the LoRa modules to the breadboards AND also to build the antennas (like this)