Eric Schneider-4 wrote: > Can you specify how much offset you see? I see an clock offset of about 2-4 ppm (almost the same with or without external clock).
Eric Schneider-4 wrote: > I presume that the transmitter is also using a precision timebase? I'm recording a signal from a DTV transmitter which is, according to its owner, synchronized with a GPS receiver. But unfortunately i can't be 100% sure of that. And as i'm using a GPS reference in the external clock input i hoped that the observed clock drift would be null but it's not the case. Eric Schneider-4 wrote: > Yes, it works Ok now i eliminated a possible source for my problem. Remains: transmitter not synchronized on GPS time, GPS reference not good, error in my post-processing to find the clock drift... I continue the investigations to find the probelm source. Eric Schneider-4 wrote: > > On Sun, 2010-06-13 at 08:12 -0700, Damien S. wrote: >> Hi all, >> I'm trying to use the external clock input of the usrp2 with WBX in >> receive >> mode. Unfortunately after processing the recorded signal there is still a >> clock drift despite the fact i'm using a GPS reference clock. So i >> suppose >> that i'm making something wrong. > > Can you specify how much offset you see? > > I presume that the transmitter is also using a precision timebase? > >> 1) I'm using a square 10 Mhz reference from a GPS receiver (Novatel OEM4) >> which has a 300 mV peak-to-peak amplitude -> this amplitude is sufficient >> ? > > I'm not familiar with that unit, but 300mV should work. > > I've used a Trimble Thunderbolt and a Jackson Labs Fury GPSDO without > issue. > >> 2) I activated the external clock by selecting the external SMA option in >> the usrp2_source block in GRC. Could somebody confirm that is method >> works ? > > Yes, it works. I just tested the GRC source and sinks with a signal > generator and my USRP2 definitely tracks the "External SMA" clock. > > --Eric > > > > _______________________________________________ > Discuss-gnuradio mailing list > [email protected] > http://lists.gnu.org/mailman/listinfo/discuss-gnuradio > > -- View this message in context: http://old.nabble.com/Using-external-clock-with-USRP2-WBX-tp28871938p28891119.html Sent from the GnuRadio mailing list archive at Nabble.com. _______________________________________________ Discuss-gnuradio mailing list [email protected] http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
