To compute a meaningful difference, you need the same reference time at
both motes. If you just need an approximation, and not something /very/
precise, get the local time at the sender A, let the receiver B send
back another packet as soon as it receives the first one, and read a
second time the local time at A upon the reception of the reply. If you
divide the difference by two, you'll get an approximation of what you
want.

On Thu, 2007-10-11 at 10:52 +0200, sara k wrote:
> Hi,
> I would like to measure the time it takes to receive a packet from one
> mote to the next one.
> so I done the following:
> - I read the time at the first mote by using pkt->stime = call
> Timer0.getNow(); and send the packet to the next mote.
> - in the second mote again I read the time pkt->rtime = call Timer0.getNow();
> and calculate the difference rtime-stime.
> Is that right? or i have fist to synchronise the motes before doing
> that !  what do you think?
> what is the difference between get() and getNow()?
> 
> Best
>   Sara

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