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Re: [Discuss-gnuradio] Some questions regarding timestamps on packets
From: |
Eric Blossom |
Subject: |
Re: [Discuss-gnuradio] Some questions regarding timestamps on packets |
Date: |
Tue, 19 Aug 2008 15:21:44 -0700 |
User-agent: |
Mutt/1.5.17 (2007-11-01) |
On Tue, Aug 19, 2008 at 02:53:57PM -0700, call5_99 wrote:
>
> Hello,
> I am new to GNU radio. So far I have been playing with benchmark_rx
> and benchmark_tx. Now, I am trying to estimate the distance between the
> transmitter and the receiver. For this I need a very accurate timestamp on
> my packets. So my questions are-
>
> 1) I need the time stamp in the order of nano seconds. Is it possible to get
> such accurate timestamp with GNU radio?
The best we're likely to do with the USRP is 1/64e6 == 15.625ns
This is based on the frequency of the master clock in the FPGA.
The master clock is not locked to any kind of a global reference.
> 2) How do I add timestamp on packet headers? Though I saw many posts on
> packets with timestamp, I didn't find any, which explained how I go about
> adding the timestamp at transmitter end, and retrieve it at receiving end.
Folks are working on sorting out the code that handles timestamps right now.
Eric