I'd like 1 circuit to be simple and very light. I'd like to measure distance up to 10m with 34cm accuracy. Will this work?http://arduino.cc/en/Tutorial/Ping?from=Tutorial.UltrasoundSensor
But different. Here is my modification...
My idea is to put the sender in the small airplane or helicopter. It will simply beep exactly every 0.1 or 1 second. The receiver will store the milliseconds and a number of milliseconds it's drifting per ping when it's 1m away not moving. This might be +-0.52ms, for example, which could be determined by waiting for 100 cycles or 100 seconds. All I need is an accurate clock that's small. Obviously the 2 clocks do not need to be in sync. One can even drift by 1%. As long as they are consistent. Can I use a 555 for the sender? Arduino Uno timer for receiver? Do you think I will get 34cm accuracy? Can I do better? Can I share the main helicopter battery? Or watch battery.
Sound is 343m/sec. So 1ms is about 34cm.
I realized this will not work for long. The code will have no way of knowing if it slowly moved away to 10m, or drifted 30ms over time. It will have to be reset to a known distance every few minutes?http://www.ti.com/lit/ds/symlink/lm555.pdf
Disregarding voltage and temp changes, it should continue to be accurate within 1%?
How much could it vary from 1sec to the next? I think much less than 1%.
Any better ideas? Please.
Update: Can I use the hardware in the first link together with a Nano or Picaxe to receive a ping and send one back after a short constant delay? Is there a complete piece of hardware that already exists to do this for the consumer market? Which idea do you like best so far?