I bought one a while ago and have been in contact with Symmetricom. The
data sheet is confusing. These do indeed have a 58.9824 MHz oscillator
and CANNOT be changed to 10 MHz. They can be changed to divide by N >=
2 to include 29.4912 MHz, 9.8304 MHz, and even 32.768 kHz if you wish,
as has been said, to have a very accurate watch or RTC.
They do NOT include the PPS disciplining function. The PPS output can
be enabled, but I have not figured out a good way to synchronize it.
PPS output does not change when the divide by N is changed.
The analog and digital frequency controls can be enabled and are functional.
A AD9851 DDS fed 29.4912 MHz and set to multiply by 6 could give
10.000000003051758 MHz, off by ~3 E-10, well within the range of the
digital control.
73,
David
On 6/2/13 5:19 PM, Tom Miller wrote:
----- Original Message ----- From: "Chris Albertson"
<albertson.ch...@gmail.com>
To: "Discussion of precise time and frequency measurement"
<time-nuts@febo.com>
Sent: Sunday, June 02, 2013 3:16 PM
Subject: Re: [time-nuts] Cheap 9.8Mhz Sa.22c's
What are you planning to do with the 10MHz signal. In some cases you
can
simply use 9.8304MHz. For example my plan to drive a DDS chip. Nominally
the DDS wants 125MHz but iif I put in some odd-ball thing like
119.6MHZ all
that means is I have to change the binary word I load into the DDS chip.
In fact that could work. Use the 9.8305 to drie a DDS then have the DDS
synthesize what you really want. It will be as stable as the Rb. but as
accurate as 1/2 the step size of the DDS.
-
And then you can make the fine frequency adjustments to the Rb 9.8 MHz
in software.
Regards,
Tom
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