[time-nuts] Phase jumps of HP3325A synthesizer ???

Magnus Danielson magnus at rubidium.dyndns.org
Sat Jul 7 18:27:40 EDT 2007

From: SAIDJACK at aol.com
Subject: Re: [time-nuts] Phase jumps of HP3325A synthesizer ???
Date: Sat, 7 Jul 2007 17:30:45 EDT
Message-ID: <d45.d01a6d9.33c16005 at aol.com>


> For an interesting in-debth analysis on a competitive approach please  see 
> Tom's excellent investigation of the FireFox Signal generator  on his website 
> (thanks again Tom):
> _http://www.leapsecond.com/logs/said/4.htm_ 
> (http://www.leapsecond.com/logs/said/4.htm) 

Nothing in there which actually explains the internal structure, only
measurement results.

> One comment: as Tom explains the FireFox has a native DDS mode with 32 bits  
> resolution, this is probably comparable to the HP3325.

Not by far. Check your facts. The HP3325A/B has the equalent of 48 bits, but
its synthesis is of strict BCD form. If you want to acheive integer multiples
of some power of 10, then you need such strict BCD forms. For other
applications will binary approaches do just as well. If you don't use the
proper base you will get "arbitrary" phase-creeps (really small frequency
errors) from what you beleived you ordered with that dial.

Modern replacements such as HP33120 and HP33250 are nice, but uses binary DDS
approaches rather than BCD DDS approaches.


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