1 PPS input for USRP2

GNU Radio
1

Hi,
I just saw the specifications for USRP2. I wanted to know the use of the
1 PPS and 10 MHz inputs.
These are standard outputs of a GPS unit. So is it just a set of
external references or they are used in the ethernet time stamping?

Regards
Subodh

2

subodh chiwate wrote:

Hi,
I just saw the specifications for USRP2. I wanted to know the use of
the 1 PPS and 10 MHz inputs.
These are standard outputs of a GPS unit. So is it just a set of
external references or they are used in the ethernet time stamping?

The USRP2 has a 100 MHz clock internally. That clock will be locked to
the 10 MHz reference you provide.

Samples can be time stamped, and that time can be calibrated to the 1
PPS signal. In the most general case, that 1 PPS input just goes
directly to the FPGA, so internally you can do whatever you want with
it.

Matt

3

Samples can be time stamped, and that time can be calibrated to the 1 PPS
signal. In the most general case, that 1 PPS input just goes directly to
the FPGA, so internally you can do whatever you want with it.

Is there a standard way to get timestamps on samples, or does this
require verilog programming?

juha

4

On Sat, Sep 13, 2008 at 03:05:18AM +0300, Juha V. wrote:

Samples can be time stamped, and that time can be calibrated to the 1 PPS
signal. In the most general case, that 1 PPS input just goes directly to
the FPGA, so internally you can do whatever you want with it.

Is there a standard way to get timestamps on samples, or does this
require verilog programming?

juha

There’s a timestamp associated with each frame of samples.

Eric