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| | |  Phlog: Eightbitswide
| | |   
| | |  Date: 5-22-24
| | |  Subject: Reyax Lora Modules
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  v    Created on the Agon, a z80 based single board computer.
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Summer is here and I thought it might be fun to have an excuse to get
some quality outdoor time and a new project for my AgonLight computer
so I purchased a couple RYLR998 modules from REYAX (via Amazon) for
about $12 a piece.  These tiny Lora radios have been around for a 
couple years, and there are many videos on Youtube boasting that they
will transmit up to 12 miles "line of site".  I suspect that this
is an "idea" condition for these that I have yet to test personally.
My first impression of these radios is just how tiny they are.  The
module itself is around the size of a US Quarter with a small spring-
line antenna that is about an inch long.  They communicate via serial
interface much like sending data/commands to an ESP32 module.
The AgonLight has a free UART interface that is accessable by some
clever BASIC/ML code created by another community member, so I 
plugged them into my computer using a USB-TTL adapter and lowered the
baud rates of the modules to 9600 baud to make them a little friendlier
with BBCBASIC on the Agon.  Commands need to be formatted a little,
before sending them to the deivce.  You can't simply load a terminal
program and start typing the command character by character, but
Ardunio has a terminal which will allow you to send a line of data
to serial followed by CR/LF which gets the job done.  It was also
trivial to create a BASIC proceedure that does the same thing.

I created a simple program in BBCBASIC that sent a properly formatted
"HELLO" message out every few seconds.  The second unit I connected
to my cell-phone via a USB-TTL adatper and headed out for a walk.
My house is located in the lower side of town, meaning that there is
a rise in elevation in most direction.  It's a fairly gentle rise,
of probably 20' over the course of a mile.   Walking into downtown,
I was able to consistantly  recieve "HELLO" data to about a half mile
from my house.  This was with several large building between me and
the destination.  Next, I changed direction and started walking up
the road directly from my house.  With my transmitting Agon/Lora
module sitting on my desk on my front room, I was able to walk up
the hill to the local park about 1km away before losing signal.
That is very impressive for a module that doesn't require a license
to operate and costs less than lunch.  

My next test will be placing the transmitting side at the highest
point outside of town, raised to the sky using a friend's bucket
truck.  I'm curious if I'll be able to see anything nearing the
claims that are being made on the internet.

For those who are planning to tinker with these, be aware that
you'll need to made sure that you properly set the band to be
complient with the laws of your country.  The US allows these
on 915Mhz band.  Also, I noticed that the documentation lists these
as being CE complient at a 14Db setting.  Mine arrived set at
22Db which may require you to comply with Amateur Radio guidelines.
I'm a licensed ham, so transmitting my callsign every few minutes
should get the job done.   Check your local laws.

-8b