Many electronics and robotics applications require localization,
that is it needs to know where it is. In this article I will go through
a localization method I invented that works with all RF modules.
method of RF localization is not very accurate nor is it precise. It
does not give you exact coordinates nor does it work well indoors. However, what it does do is provide you with
the approximate distance to an object outdoors. Better yet, my method for RF
localization works with EVERY RF module that can transmit serial data.
you will need a transmitter module and a receiver module. To
demonstrate how this method works for any RF module, I will use the
cheapest RF modules I can find.Using those Transmitter and Receiver modules I got around +- 15 feet precision localization.
method of RF localization is based on the principle that the more power
a RF transmitter has, the farther the RF signal goes.
transmitter sends out a different encoded RF signal at varying power
levels. At each different power level, the transmitter sends a
different byte. Therefore depending on which signals are received, a
receiver would be able to approximate its distance from the
So after a test we would have a chart similar to this generated:
Note: Bytes were encoded using an encoding method and the minimum power for the transmitter is 2 volts , and maximum is 12 volts)
We see an obvious ( but not really linear) relationship between power level and distance.
The transmitter sets the power level and then sends the respective byte. It repeats for all bytes and all voltages.The receiver merely has to check which bytes it received and based on which bytes it received it can estimate distance.
The transmitter uses diodes ( with a 2V drop) and transistors. The diodes' voltage drops are a crude way of generating different voltage. The transistors switch the different voltages to the transmitter's power pin.
Here is a sample receiver schematic ( could really be anything with a receiver in it)