On Sat, Jan 13, 2007 at 01:21:06PM -0800, Matt Ettus wrote:
Actually the USRP v4 seems to have a VCXO already:
http://gnuradio.org/svn/usrp-hw/trunk/USRP_REV_4_2/clock.pdf
Actually, it isn't. Its a plain crystal oscillator. Selected for
very low jitter, but it does have up to 50 ppm drift over temperature.
I tried and failed to find an off the shelf 64 MHz VXCO that
would fit... perhaps my search wasn't vigorous enough. If there is
one I'd certainly want to hear about it.
I really do wish some one of the folks offering USRP type A/D
and D/A functionality would at least provide an unstuffed 10 MHz
reference clock locking circuit on their board - there are lots of
applications where it is really useful to be able to have a really
stable accurate clock and 10 MHz GPSDOs that supply a highly accurate 10
MHz reference are cheap, high performance and widely available. And
obvious the phase noise and jitter of the sampling clock is quite
critical, so an integrated solution on board with a VCXO seems more
optimum than an external board, cable, connectors and all the issues
those introduce.
--
Dave Emery N1PRE, die@dieconsulting.com DIE Consulting, Weston, Mass 02493
"An empty zombie mind with a forlorn barely readable weatherbeaten
'For Rent' sign still vainly flapping outside on the weed encrusted pole - in
celebration of what could have been, but wasn't and is not to be now either."
On Sat, Jan 13, 2007 at 01:21:06PM -0800, Matt Ettus wrote:
> On 1/13/07, Poul-Henning Kamp <phk@phk.freebsd.dk> wrote:
> > In message <1025.134.53.50.125.1168708295.squirrel@fluffles.febo.com>, jra@febo.com writes:
> > >>
> >
> > Actually the USRP v4 seems to have a VCXO already:
> >
> > http://gnuradio.org/svn/usrp-hw/trunk/USRP_REV_4_2/clock.pdf
>
> Actually, it isn't. Its a plain crystal oscillator. Selected for
> very low jitter, but it does have up to 50 ppm drift over temperature.
I tried and failed to find an off the shelf 64 MHz VXCO that
would fit... perhaps my search wasn't vigorous enough. If there is
one I'd certainly want to hear about it.
I really do wish some one of the folks offering USRP type A/D
and D/A functionality would at least provide an unstuffed 10 MHz
reference clock locking circuit on their board - there are lots of
applications where it is really useful to be able to have a really
stable accurate clock and 10 MHz GPSDOs that supply a highly accurate 10
MHz reference are cheap, high performance and widely available. And
obvious the phase noise and jitter of the sampling clock is quite
critical, so an integrated solution on board with a VCXO seems more
optimum than an external board, cable, connectors and all the issues
those introduce.
--
Dave Emery N1PRE, die@dieconsulting.com DIE Consulting, Weston, Mass 02493
"An empty zombie mind with a forlorn barely readable weatherbeaten
'For Rent' sign still vainly flapping outside on the weed encrusted pole - in
celebration of what could have been, but wasn't and is not to be now either."
