Measuring distance between two devices? (<30m, as accurate as possible)

I'm in the process of searching for a low power component that measures distance between two devices?
Since the two devices may be outdoor or have an obstacle in between, I am guessing using radiowave is probably the best option here. As IR and Ultrasonic don't work well outdoors and Lidar cannot overcome obstacles
I want to measure distance for no more than 30m and hopefully as accurate as possible.
thanks

Your question comes up about once a week, and the answer is always the same. Radio won't work and to my knowledge, no one, on an experimenter's budget, has reported accomplishing this using any other technique.

if there is a line of sight laser is the only option I know ==> Expensive.

Depending upon the background noise level (if low enough) you might consider a sort of sound echo.
Arduino 1 starts timer
Arduino 1 buzzes a piezo buzzer
Arduino 2 receives this (microphone) and buzzer back
Arduino 1 hear this and stops timer.

Alternative:
2 GPS shields and a radio wave to tell each others position (not very accurate)

Check out LIDAR

@Crossroads

  • are there detailed specifications (precision accuracy) available, I read the range = 0 - 40meter

Use the Contact Us links at Pulsed Technology & ask - I don't see any numbers.

prelim specs - https://docs.google.com/file/d/0BwbDM4W-3iVPU2JmOEpvTFdEZnM/edit -
I'll ask them,
update - request sent

Had a reply from the Pulsed LIght, LLC.


In brief, LIDAR-Lite can operate from 0-40m with cm resolution. The overall accuracy is based on the reference clock which can either be internal to the programmable logic chip we use or an external source can be used. The internal reference is advertised by Lattice as having a 5% accuracy and we use that number in our preliminary specifications for the LIDAR-Lite product. Obviously, an external source would provide greater accuracy. In testing of our prototypes the accuracy using the internal reference has generally run better than 1% and we expect that would hold true in our production sensors. The rep rate is dynamically adjustable from 1-100Hz, although at the higher rep rates the range may be limited depending on the signal strength of the return signal.

Communications is via I2C at either 3.3 or 5 VDC logic and the bit rate is 100Khz. The unit operates as a slave and we are working on implementing user assignable addressing in the production sensors. Implementing this feature in the programmable logic device is a bit more complicated than we had anticipated, so it isn’t in any of the prototypes at the moment.

I hope that I’ve addressed your questions. We do plan on having more information available online as we move toward production. If you have any additional questions, please feel free to contact me.

We are still testing the prototypes for real-world performance, which looks better than expected, so would only say that the specs may change as we release to production.

In addition to 3D Robotics writing code for their autopilot systems to support LIDAR-Lite, we also have a local Arduino group in Bend that is working on code for the Arduino micro controllers and will make that available along with other operating information as it is completed.

Please note that the information above is subject to change as it is a product in progress. Nevertheless it looks very promising!
If I get more information I will post it here.

I'll bet that performance estimate was done indoors, under controlled lighting. Given the LED light source of the stock sensor, it is very hard to imagine that it will perform so well in an out-of-doors situation, in full sunlight. That is what many people would like to see.

Got an update by mail from Pulsed light, they have a new website and among others they disclosed code for Arduino on Github. The website includes technical docs, so I have some reading to catch up....

website: - http://pulsedlight3d.com/ -
github: - GitHub - PulsedLight3D/LIDARLite_Basics: This repository contains sample code demonstrating different features and functions of the LIDAR-Lite Sensor -

This looks pretty good! They now have a laser in the standard device, and the price (US $89) seems hard to beat. I plan to order one and will report back.

If the object whose distance you wished to measure were like the face of a vice's jaw. you could project two dots of light onto it, from lines not perpendicular to the movement of the vice's jaw. And then use a simple image capture device, and image analysis to measure the separation of the dots, which would lead to distance.

Tell us more about what it is you want to measure the distance to. And how fast it will move and how often you need a new reading.

Always sparks better answers, or at least avoids useless one.