The technique used by Swedish Institute of Computer Science looks sound=20 on the surface. I just wonder whether the variations are really caused=20 by multi-path conditions. I didn't read far enough to see whether the=20 internals of the rf chip automatically generating an ack were=20 considered, nor do I know if the chip manufacturers disclose that info. =20 The researchers seem to consider the rf chip an ideal black box. My guess is that internal to the rf chip, there are the same clocking=20 and latency issues that would exist in the platform microcontroller. Did I not read far enough? Joe W On 1/25/2015 3:18 AM, RussellMc wrote: > RF Time of flight distance measurement for position location using Arduin= o > - Superb & arcane - he is pushing what he has far above normal > capabilities. Very intelligent application of laws of Physics. > > > > > Adam Fabio posted: "If you carry a cell phone with GPS, you always kn= ow > where you are on the planet. But what about inside buildings or even your > own home? Knowing if you're in the kitchen or the living room would be a > great feature for home automation systems. Lights could " Respond to > this post by replying above this line > New post on *Hackaday* > Trinket > uses RF to track you through the house > > by > Adam Fabio > > If you carry a cell phone with GPS, you always know where you are on the > planet. But what about inside buildings or even your own home? Knowing if > you're in the kitchen or the living room would be a great feature for hom= e > automation systems. Lights could come on as you enter the room and your > music could follow you on the home audio system. This is exactly the what > [Eric] is working on with his Radiolocation using a Pocket Size Transceiv= er > project. [Eric] started this project as = an > entry in the Trinket Everyday Carry Contest. He didn't make the top 3, bu= t > was one of the fierce competitors who made the competition very hard to > judge! > > The heart of the project is determining Time Of Flight > (TOF) for a radio signal. > Since radio waves move at the speed of light, this is no small feat for a= n > Arduino based design! [Eric] isn't re-inventing the wheel though - he's > basing his design on several research papers, which he's linked to his > project description . Time of > flight calculations get easier to handle when calculating round trip time= s > rather than one way. To handle this, one or more base stations send out > pings, which are received and returned by small transponders worn by a > user. By averaging over many round trip transmissions, a distance > estimation can be calculated. > > [Eric] used a Pro Trinket as his mobile transponder, while an Arduino Mic= ro > with it's 16 bit counter acted as the base station. For RF, he used the > popular Nordic nRF24L01+ 2.4 GHz transceiver modules. Even with this > simple hardware, he's achieved great results. So far he can display > distance between base and transponder on a graph. Not bad for a DIY > transponder so small if fits in a 2xAAA battery case! [Eric's] next task = is > working through multipath issues, and testing out multiple base stations. > > Click past the break to see [Eric's] project in action! > > Read more of this post > > *Adam Fabio * | January 24, 201= 5 > at 10:00 am | Tags: hackaday.io , > radar , Radicalization > , Trinket EDC contest > | Categories: Arduino Ha= cks > , contests > | URL: http://wp.me/pk3lN-BCG > > Comment > > See all comments > > Like > --=20 Joe Wronski jwronski@stillwatereng.net www.stillwatereng.net --=20 http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .