I would like to know if it is possible to connect an RF(radio frequency) module to my smartphone and find the distance between them with an accuracy of about +/-2 meters. To find distance I believe I have to use RSSI level (Received signal strength indication). I have considered using bluetooth but I would like to find better alternatives because I need more range than bluetooth can provide. I need to measure distances up to 100m/300 feet. I found some module from ebay that transmits 433MHz. Is it possible? Thank you.
To do this with RSSI is, to put it mildly, very hard. There is so much influence of surroundings, reflections, etc. that makes it virtually impossible to do this in any situation where you are no in an anechoic chamber. Not to mention the impact of antenna directivity, how you are holding the device, etc.
I think it would be easier to use something like GPS to determine position and transmit that, and calculate the distance by just looking at the distance between the two gps locations.