For a new product, I'd like some help in understanding what technology would be best for creating a wireless connection between two moving devices and having them constantly monitor the distance between the two.

I only need accuracy down to 1m or 1ft and then would love to know the max that it could go up to. Preferably, I'd like one of these devices to be a smartphone so if possible can this be done through wifi/bluetooth without any additional hardware? If not, what other technologies would be ideal for this type of measurement?

Assume the objects are both constantly moving in the same direction but only at about 2-6 mph.

Essentially I'm looking for one to be the master and for it to monitor how far the other object is away from it.

This question is along the right path: Options for short range distance determination between two objects

  • \$\begingroup\$ Differential GPS may be worth investigating. \$\endgroup\$ – pjc50 Mar 23 '13 at 12:56

You will not get the accuracy you need with wifi or Bt. Rssi is not reliable measure. Ultrasonic is an easy answer. Depending on your smartphones microphone frequency response you may get away with just adding an ultrasonic transmitter and use wifi and ultrasonic in tandem to figure out distance. Wifi would be instant and sound will be slower. You may have to pull tricks to eliminate wifi packet delays etc but I see that they can be worked out.


protected by Kortuk Mar 23 '13 at 0:39

Thank you for your interest in this question. Because it has attracted low-quality or spam answers that had to be removed, posting an answer now requires 10 reputation on this site (the association bonus does not count).

Would you like to answer one of these unanswered questions instead?

Not the answer you're looking for? Browse other questions tagged or ask your own question.