[time-nuts] AD9548 - Clock IC Generates Up to 400 MHz from 1 PPSGPS Signal

Ulrich Bangert df6jb at ulrich-bangert.de
Thu Jun 11 04:48:42 EDT 2009


> However it does discipline the DDS outputs as intended.
> It is somewhat akin to Ulrich's approach perhaps without the 
> robust outlier rejection.

Surely AD has not copied from me, but yes indeed this looks similar to my
approach. The output noise may by tamed by loosely coupling a high quality
OCXO to the output. Perhaps one should think over a circuit that

a) surpresses PPS outliers

and

b) applies sawtooth correction to the PPS

Best regads
Ulrich Bangert

> -----Ursprüngliche Nachricht-----
> Von: time-nuts-bounces at febo.com 
> [mailto:time-nuts-bounces at febo.com] Im Auftrag von Bruce Griffiths
> Gesendet: Donnerstag, 11. Juni 2009 07:42
> An: lester at veenstras.com; Discussion of precise time and 
> frequency measurement
> Betreff: Re: [time-nuts] AD9548 - Clock IC Generates Up to 
> 400 MHz from 1 PPSGPS Signal
> 
> 
> However it does discipline the DDS outputs as intended.
> It is somewhat akin to Ulrich's approach perhaps without the 
> robust outlier rejection. This approach would allow a wide 
> range of relatively stable low noise sources to be used 
> including those that may have drifted out of adjustment 
> range. One drawback for some applications is the relatively 
> high phase noise floor.
> 
> Bruce
> 
> Lester Veenstra wrote:
> > Sync to 1 pps but will not discipline the frequency source
> >
> >  
> > Lester B Veenstra  MØYCM K1YCM
> > lester at veenstras.com
> > m0ycm at veenstras.com
> > k1ycm at veenstras.com
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> > -----Original Message-----
> > From: time-nuts-bounces at febo.com 
> [mailto:time-nuts-bounces at febo.com] 
> > On Behalf Of christopher hoover
> > Sent: Thursday, June 11, 2009 5:26 AM
> > To: time-nuts at febo.com
> > Subject: [time-nuts] AD9548 - Clock IC Generates Up to 400 
> MHz from 1 
> > PPSGPS Signal
> >
> >
> > [fyi -- this may be of general interest, but n.b. that this A.D.
> > marketing - ch]
> >
> >
> > Clock IC Generates Up to 400 MHz from 1 PPS GPS Signal
> >
> > The AD9548
> > 
> <http://www.analog.com/en/clock-and-timing/clock-generation-an
d-distribution
> /ad9548/products/product.html> 
> is the first clock chip in the industry to directly generate up to a 400 
> MHz output clock, with extremely low phase noise, that is locked to a 
> standard one pulse-per-second (PPS) GPS clock signal. This performance 
> is a result of combining Analog Devices' proprietary direct digital 
> synthesis (DDS) technology with a state-of-the-art digital phase-locked 
> loop (DPLL). Other solutions for synchronizing to the GPS 1 PPS source 
> typically rely on one or more frequency upconversion steps. Maintaining 
> low output noise, while providing over eight orders of magnitude of 
> frequency scaling (1 Hz input to over 100 MHz output), is a significant 
> challenge. The AD9548 is able to mitigate this effect thanks to a 
> digital loop filter capable of bandwidths as low as 1 MHz (10 Hz to 3 Hz).
>
>
> /
> /
>
>
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