I am working on a project and need help with one of the sensors. I have a car (4 feet by 5 feet) that starts off at a docking station and without user input moves around avoiding obstacles. One of my constraints is that I have to stay within a certain distance (about 150m/500 feet) of the docking station. I have discounted sonar and IR sensors because they require the two objects to be in the line-of-sight of another and in most scenarios there will be obstructions between the car and the docking station (also I haven’t found sonar sensors with 500 feet range).
After doing a lot of research, I have come to believe that using RF transceivers is the best option for this task. What I intend on doing is having one transceiver 1 on the docking station and transceiver 2 on the car. I will send out a ping (a byte with a unique bit combination) from transceiver 1 and transceiver 2 will pick up the ping. As soon as transceiver 2 picks up the ping it will send a ping of its own with a different bit combination and this time transceiver 1 will pick it up. As soon as transceiver 1 picks up the ping it will calculate distance between the two objects using the time it took between initially sending out the first ping and receiving the second one (I will of course have to experimentally find the ping speed).
I am using an Arduino and am not sure what kind of transceiver to use for this purpose. After some research, I understand that RFM69CW and RFM12B are viable options but I have no idea how to use them, but before I buy them has anybody here who has worked with them know what other hardware I would need to get them working?
And how about programming? Does anybody have sketches for these boards? Also, of the three which frequency is most reliable? I will be using the car in a residential area, and was wondering if someone has experience with the three and could relate.
Summary of my challenges:
- Is there an easier way than RF transceivers of finding distance between two objects not in line-of-sight of one another?
- Are the RFM69CW and RFM12B the best options for me? If not then what are some worth considering?
- What other hardware would I need along with these boards to get them going?
- Does anybody have Arduino sketches for using these boards?
Thanks very much for your help!