Wireless Access

Hello,

If I were to deploy a network that were to use time difference of arrival (TDOA) for location based serivces, how do I syncronise my APs?

I understand TDOA works by measuring the relative arrival time at each AP. Accurate timing information is required for the calculation to be correct. Is this done with NTP from a suitably accurate master clock server on the network?

Thanks

Kliba,

There is only one commercially available TDOA implementation on the market to my knowledge, which is from AeroScout.

They sell TDOA sensors which are custom designed, and which coordinate timing between themselves.

NTP is not accurate enough for this.   You are talking nanosecond level accuracy.   

AeroScout is an Aruba partner.  Please contact your AeroScout sales rep for more information.

Thanks for the reply - I agree with your assumptions. NTP didn't sound quite right to me. I wasn't sure if the TDOA was applied at the antenna array (Angle of Arrival) or across multiple recievers.

I will look into the AeroScout devices.