1 PPS for USRP2?

GNU Radio
1

Hi,

   I am trying to synchronize two USRP2’s using GPS receiver of 10MHz
and 1 PPS.

recently ,i ran into some problem with 1 PPS output from GPS receiver,
but output clock 10 MHz seems to be perfectly alright.

  1. Do i really need 1 PPS input along with 10MHz Clock for USRP2…?
    Â 2) Is it not possible for me to use only the clock 10MHz and not the 1
    PPS, to synchronize 2 USRP2’s.

 3)If it really needed, then can i generate 1PPS from signal generator
and feed it to USRP2.,

but if i do that, How do i sync the rising edge of the 1 PPS to the
Rising edge of the Sine wave(10MHz)Â ?

Thanks
KRISHNA S

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2

Hi Jermy,

              1PPS requirement is not mandatory. To acheive
synchronization between two USRP2’s i have done the following,

  1. Change the firmware in both USRP2’s SD card
    Â Â Â in txrx.c i have added
    Â Â Â clocks_enable_test_clk(true,2);
    Â Â Â clocks_mimo_config(MC_WE_LOCK_TO_SMA);
    Â Â Â Â just before whilr(1) loop

  2. i have connected 1 GPS source providing reference CLOCK 10 MHz 1.2
    Vp-p, to 2Â Â Â Â Â Â
    Â Â Â USRP2’s with a T-splitter.
    Â Â Â If not GPS, u can also use signal generator, generate a 10MHz
    1.2Vp-p and feed thisÂ
       to the REF CLK of USRP2.

This should solve the Synchronization problem.

Regards
KRISHNA S

— On Sun, 9/5/10, jeremy ward [email protected] wrote:

From: jeremy ward [email protected]
Subject: [Discuss-gnuradio] 1 PPS for USRP2 ?
To: [email protected]
Date: Sunday, 9 May, 2010, 7:48 PM

Hey Man

Did you have any luck with this. I too am trying to get PPS going. Any
advice?

jer