[time-nuts] Symmetricom CSAC is Cs acting like a Rb unit

John Miles jmiles at pop.net
Wed Jan 19 01:39:10 UTC 2011

> -----Original Message-----
> From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com]On
> Behalf Of Tom Holmes
> Sent: Tuesday, January 18, 2011 4:43 PM
> To: 'Discussion of precise time and frequency measurement'
> Subject: Re: [time-nuts] Symmetricom CSAC is Cs acting like a Rb unit
> OK, so aside from the price of this toy, are there any performance reasons
> why this itty bitty gizmo wouldn't be quite useful to my ham
> friends who do
> portable/mobile microwave operation, as opposed to dragging along
> a GPSDO or
> OCXO? Think in terms of frequency error at 10 GHz, 24 GHz or even higher.

Bragging rights!  What else is needed?

Apart from that, until we see some PN and ADEV/MDEV plots, there's no way to
say if it would be better than an eBay-special rubidium standard in any
corner of the performance envelope.  This thing might sound like so much
white noise if you multiplied it to 10 GHz+... or it might work well.

Unless Symmetricom is positioning it as some kind of loss leader, I'd guess
that the $1500 price point means that they are following the usual Rb recipe
of dragging a cheap crystal oscillator around with a relatively fast loop.

Warmup time and low power consumption shouldn't be dismissed as selling
points, though.  Conventional Rb standards lock quickly enough, but they
don't live up to their full performance potential until they've been on for
several hours.  If the only major heat source is the cesium oven, the VCSEL
illumination scheme might offer the best overall time-to-stability
performance of any source ever produced.

And you can always use it to discipline another OCXO if you don't like the
one it comes with.

-- john, KE5FX

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