Re: [Discuss-gnuradio] grGPS Preliminary Schematic

[Marcus Leech]

> Farnell sell 32.768 MHz crystals (They're not what you'd call cheap though - 
> AU$17). Hmm they have 16.384 MHz ones for $12.81. Still not cheap..
>
> Also, I think getting 32.768 MHz from 4Mhz with a PLL would be pretty 
> difficult (if not impossible)
>
>   
Given that you haven't looked into the PLLs on the FPGA, it's rather too 
early
 to conclude that you couldn't synthesize 32.768Mhz from the 4Mhz reference
 clock that's already on the USRP.

Given reasonable dividers for both reference and VFO, I can't see why 
synthesizing
 32.768Mhz would be all that difficult.  I can understand why you might 
want to
 use a dedicated oscillator--you don't have to muck with the FPGA.   
But asserting that
 it's "difficult (if not impossible)" is hard to support if you haven't 
looked into it.