Some questions regarding timestamps on packets

GNU Radio
1

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?
  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.

If someone could suggest me examples of codes where timestamps have been
delt with, I would be grateful. Thanks.

Prasanna.

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2

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.

  1. 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

3

Hello,
Thank you for the clarifications.

Prasanna.

Eric B. wrote:

adding the timestamp at transmitter end, and retrieve it at receiving
[email protected]
Discuss-gnuradio Info Page

–
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