Hi I’m fairly green when it comes to RF technology in circuits.
Here’s my problem: I need a low power RF transmitter module (3 - 5v) for my application. It’s a small embedded device and all it does is broadcasting a short ID to a base station.
My circuit is very small, it’s a battery powered AVR. The AVR holds the unique ID to be broadcast when a certain logic criteria is met.
And to make things complicated, There will be multiple of these broadcasting their IDs to the base station, probably up to 1000 devices broadcasting once per 5 seconds which is 200 times per second. I need the range about 500ft or more.
I’m guessing something that broadcasts in the ICM range will work but I’m open for any design ideas.
So long story short; What TX/RX chips would be good to use? Also, how what would be the best way of getting a message through in such a crowded network?
Wireless thermometers and the like have no receiver. They transmit every few 10’s of seconds to meet FCC (or equiv) regulations for such transmissions in unlicensed spectrum. This also conserves battery life. They rely on the receiving unit to cope with garbled transmissions due to collisions with other dumb transmitters. Some probably randomize the time interval to minimize chance of syncopation.
Today’s two-way data radios, such as the XBee (sold here) are a vast improvement but at $20-30, may be an overkill.
Yes it’s transmit only. However using transceivers would mean that I could implement a simple protocol that checks whether the information sent alright, otherwise it gets resent at a later time, say 100 milliseconds later. For my application the exact timing is not that crucial.
I’ve looked at XBees, they tick the boxes for low power and range. They have good data speed but the price is quite steep.