#109 Types of 433Mhz RF modules in ZA

Recently I have been using wireless technologies for a few projects.

While looking for a balance between price, functionality and disposability I decided to focus on the 433Mhz RF modules.

These use a free spectrum and have been around for a long time. There’s is a few different types and kinds, with LORA being kind of new and better in almost every way but this comes at a high price compared with the standard 433 RF modules.

So I purchased a few receivers and transmitters from electronics suppliers located in South Africa.

All my tests consisted of running the 4 receivers at 5v and a single 17.3cm straight LAN cable strand as an antenna. The signal sent was a 23bit ASK signal with a pulse length of 1200ms.

All 3 transmitters were tested at 3.3v with a single 17.3cm straight LAN cable strand as an antenna.

The transmitters testes were the FS1000A, CYT1 and the WL102-341.

The Tests were done on farm land.

All transmitters could trigger the receivers at 400m line of sight but only a few could penetrate foliage and a galvanised steel shed.

I only needed MAX 400m which is why I stopped there but some sources claim up to 600m – 800m + for these superheterodyne modules. Not as good as LoRa but for the price what reason do I need not to use them?

*Sidenote Using RF or LoRa in conjunction with a 2.4G Wifi module like the ESP32 or even 3G/4G modules can create multi dimensional divers systems. where we are leveraging the long range and penetration + power output of 433Mhz and 868Mhz but also allowing packets of data to connect over the internet to be stored on a server for data analysis and the creation of graphs to make the data more visually appealing.

Currently I do have some pilot devices and hope to one day make some good quality sensors in 3 different tiers:

1. Cheap and disposable sensors
2. Affordable long term sensors
3. High end sensors

These will be focused on use within rural outdoor areas and I will have a version with Gerber files and schematics etc. available for anyone to download and make for themselves. However the more refined version with a nice enclosure and style will be sold commercially since I do want to be paid for my work.

Back to the modules..

The transmitters that support 5v could penetrate a little better sometimes.

The position of the transmitter/receiver could also greatly affect the received signal especially at range.

Also during summer and during rain the signal was worse with the foliage and water most likely absorbing and/or reflecting the signal

All receivers were superheterodyne with a crystal and I did not use any counterpoise though it would help in some circumstances it makes the receiver unpractical and large.

Some people may wonder why I am using these modules instead of the fashionable LoRa modules. This is simply due to cost and availability.

Designing a good circuit cost time and money. Inserting said circuit into an extremely hostile environment like for example.. rural South Africa is an even more costly exercise…

I have had devices damaged by the sun, damaged by water, damaged by ants, damaged by cows, damaged by some kind of rabid animal (assuming jackal) The list goes on.

AND I have not even mentioned the human element… devices damaged by criminals some even STOLEN… for what? You telling me that criminal is sitting in the bush conspiring to reverse engineer my simple circuit and RF protocol and some how will be able to defeat Microchips code protection? I highly doubt it but it is possible…

So now I hope you can understand why these cheap modules do work and are very useful + inexpensive for my purposes.

I also have LoRa versions but for now I only use those when distance and extreme sensitivity is needed.