Tag Archives: RADIO

DIY LORA MODULE

31 August 2024 Cale Leave a comment

#115 Making A DIY LoRa Module

2x DIY LoRa RFM95W modules with adapter boards.

When taking a closer look at the DIY aspect of lora I wanted to test LoRa peer to peer.. E.G multiple peers to one peer (NOT LoRa WAN) I noticed that the actual radio PCB is difficult to use when going the traditional through hole way… adapter boards do exist but are few and far between at least in SA. you can make your own for manufacture but then rather create your entire product PCB for manufacture.

Even with this drawback I was able to source old adapters for one of the very firs modules the: RFM95W. In South Africa we are mostly using 868Mhz although 433Mhz modules are around I don’t see them being super common in terms of LoRa modules.

The modules I used have a footprint for adding a female SMA connecter for easy antenna connecting.

Parts used:

2x RFM95W 868Mhz LoRa module transceiver
2x 3.3v active buzzer
2x 1 pole dip switch
2x TP4056 module with protection ICs
2x ATtiny404 MCU
2x NCV8163 3.3V LDO
2x SSD1306 128×32 OLED
2x 2pin 2.5mm JST battery connector
2x Headers and jumpers
2x 13400 3.7V 550mAh
2x 10k resistors
2x 220R resistors
2x SOIC to DIP adapter PCB
2x BC547 transistors
Some 0.9mm tin plated copper wire
Some 0.255mm PVC insulated wire

After checking the PCB I commenced with testing the devices. Unfortunately the test area has largely mountains terrain
the signal works really well and penetrates better through foliage on the mountains terrain but once there is a full on mountain in the way the signal stops. so in this retrospect the devices are better then a radio which was quite interesting but makes sense because data is being sent and uses less bandwidth then interpreting voice audio. Also the error checking for LoRa helps a lot.

Some more pros for the LoRa is that its a transceiver out of the box with RSSI functions included. Also for increased range and/or quality the spreading factor and signal bandwidth can be adjusted.

Although there’s many pros regarding LoRa I still tend to use simple 433.92 RF modules without issue at least in my situation with rural areas under about 3KM at and given point.

So it really becomes more of a cost factor than anything else. Although I’m happy selling a custom LoRa product for compatibility with LoRa WAN or some other requirement with a similar principal. Plain old generic RF is still cool in my book.

Electronics, Experimental

COMMON RF MODULES IN SOUTH AFRICA

27 February 2024 Cale Leave a comment

#109 Types of 433Mhz RF modules in ZA

FS1000A module at 5v no attenuator just using antenna.

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 crude module actually has more power and range at 5V but I am using them at 3.3v for super low power applications so In this case the module loses.

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:

Cheap and disposable sensors
Affordable long term sensors
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.

Electronics, Experimental

MOTOROLA CM140

18 July 2023 Cale 10 Comments

#102 Reprogramming an old CM140 radio

If you do not have the code plug password or a saved code plug with the radios serial number then this post is for you.

I recently came into possession of 2 Motorola CM140 25W radios. These radios belonged to my grandfathers old security company which is now dissolved, however amongst a lot of the kit I was able to save a few gems.

Upon inspection these radios were in immaculate condition despite there age. I was able to power up both radios only to find that they were programmed to one channel and when I used Commercial Series CPS (customer programming software) I could not read or write to the radio since the code plug was password protected.

Luckily I found a sample code plug for the model of CM140 radio I had. This allowed me to clone and change the password of the radio using the sample code plug now I can read/write to the radio

I have created a step by step document on my GitHub page here.

ESP32, Experimental

LORA SETUP

22 October 2021 Cale Leave a comment

#78 Setting up the LoRa T-Beam

Living on a farm I often encounter communication issues coupled with the urgency to communicate when catastrophes strike. Therefore in my quest to find suitable backups and backups to the backups I stumbled upon the LoRa system. Specifically the LoRa boards in the T-Beam configuration using the Meshtastic firmware + Android app which allows text message communication over a few kilometers in my case.

After testing them I came to the conclusion that they do work and reliability, however they can get damaged easily and the quality of boards and components used is not up to the bar of commercial motherboards such as gigabyte PC motherboards as an example.

My final opinion being: they work and I would use them as one of my “coms” layers however I would not put the T-Beam on par with a mobile phone the quality is simply just not there.