Synchronize USRP using 5Hz pps

Hello,

I am using Garmin 18 5Hz PPS clock for USRP synchronization.

This is the GPS: Garmin | Select a Location

However, because it is 5Hz PPS not 1Hz, the synchronization looks not
working properly.

I got following message on the time stamp reading after 1 sec.

“Creating the usrp device with: …
Current recv sock buff size: 50000000 bytes
Synched to PPS: Reading time 1s later: 0.829645”

As you see, the time reading after 1 sec is smaller than 1 sec.

I am wondering if I have to buy another GPS for 1 Hz PPS.

Thanks.

  • Sangho

Using a 5Hz PPS is not fundamentally different than 1Hz. That should not
be a problem.

Make sure your pulse has the correct levels:
http://www.ettus.com/uhd_docs/manual/html/usrp2.html#pps-pulse-per-second

-Josh

It passes the pps test.
I just thought it is not working properly because the clock is too fast
(5x
than pps), and reading time is less than 1 sec.

If that is normal, then my GPS pps signal may be working correctly

  • Sangho

Creating the usrp device with: …
Current recv sock buff size: 50000000 bytes
Using Device: Single USRP:
Device: USRP2/N Series device
Mboard: USRP2-REV3 mboard
RX DSP: USRP2-REV3 ddc0
RX Channel: 0
RX Dboard: USRP2-REV3 dboard (rx unit)
RX Subdev: XCVR2450 (0x0061)
TX DSP: USRP2-REV3 duc0
TX Channel: 0
TX Dboard: USRP2-REV3 dboard (tx unit)
TX Subdev: XCVR2450 (0x0060)

Set time to known value (100.0) without regard to pps:
Reading time 1 second later: 101.000101

Set time to known value (0.0) at next pps:
Reading time 1 second later: 0.871597

Success!