Short Distance Communication

[TourdeGanger1776]

Hello,

I need a wireless solution to broadcast one Byte of information from a stationary post to passing cars travelling at a speed from 20-100 KM/ hour. I ruled out WiFi because I will not want to use authentication.

What is the most effective communication protocol we can use to achieve our goal?

 

[betwixt]

It would have to be sent serially and acheiving sync with just one byte is difficult. You will probably need some pre-amble to allow the data to find the start and stop bits. In view of the very tight beam you would need, I would suggest doing it optically, for example using IR LEDs with filters or lenses to narrow and concentrate the beam. Passing cars would use an IR sensor to pick up the byte. A similar system was used here years ago to confirm the location of buses, they carried a bar code which was scanned by a laser at each bus stop and then sent back to a control center using a modem.

Brian.

 

[shell.albert]

i do not recommend to use the IR LED. limited to its straight line transfer character,you do not use it in large angle range.
look at the si4432 chip producted by silicon labs,i did a project with it in a few years ago,everything is ok so far.
for simple and effective communication protocol,you'd better do not transfer one byte only. it's not difficult to setup
a strong protocol. but there are some necessary elements in a protocol,as follows:

sync head + function code + function content + crc + frame end

Just advise for refernece.