Hi Don, Jim, that is the one I was refering to, It has a VCO as the source
(all part of the AD4351) but I think your description of the unit is more
accurate that mine. Contact him directly he is keen to contact new areas and
hobbyists. There are two units one is a source with 4 output levels, I
believe he sells that on eBay at $280 but direct contact may get you a
better deal. There is a version with a calibrated attenuator but this has FM
capability which adds to the VCO control and may not be good for PN. I think
this sells for $340.
Robert Yarbrough rob...@rf-consultant.com (blame me for airing his ID
:-)) )
Alan
G3NYK
----- Original Message -----
From: "Don Latham" <d...@montana.com>
To: "Discussion of precise time and frequency measurement"
<time-nuts@febo.com>
Sent: Tuesday, October 07, 2014 9:19 PM
Subject: Re: [time-nuts] fast switching quiet synthesizer
I have two "versions" of the ADF4351 dds. One is the AD eval board, and the
other the TPI synthesizer
(http://www.rf-consultant.com/calibrated-signal-generator/) at $280 that
might
do the job. The latter device performs well. It will be as good as the
4351, I
think. It has a programmable attenuator. A good price. Requires a
Healthy!
USB port.
Don
Magnus Danielson
You should be able to use DDS test-boards and by timing your last write,
you should be able to time the frequency jump.
The STEL-1173 takes 6 bytes, but writing the last one latches all 6
bytes over to a single 48 bit word. I expect that other DDSes have the
same distinct transfer-phase if you only look in the datasheet for the
details.
Some of the modern DDSes can take 10 MHz directly and step it up
internally before hitting the DDS core, but it may be that you need to
synthesize a higher clock from the 10 MHz first.
Cheers,
Magnus
On 10/07/2014 07:02 PM, Jim Lux wrote:
At work, I'm putting together a multichannel stepped frequency CW radar
breadboard, and I'm looking for something to serve as a source that I
can step quickly.
I'm looking at stepping every millisecond or so. Right now, I use a
Ardunino type microcontroller driving a serial DAC driving a VCO, but
that's a bit wonky and noisy, although it's easy to get the step timing
right on. The spectral purity is, shall we say, downright ugly.
Since I'm going to be doing precision ranging with this, the spectral
purity has to be reasonably good (not 1E-15 at 1000 seconds good,
fortunately)..
I was thinking about a PTS synthesizers (beloved of time-nuts for all
kinds of reason), and they're nice because they are quiet, and switch
really fast (microseconds). However, they all seem to have BCD or GPIB
interfaces (only). Sure, I can code up something on an Arduino or other
microcontroller to drive the BCD on the PTS, but maybe there's something
else out there that might work as well? And is already off the shelf.
I could hook a Prologix on the back of a PTS with GPIB, and hit it over
the ethernet, but I'm not sure I'd be able to get the steps to occur
when I want them (ethernet and determinism do not go well together).
Maybe some DDS in a box product? That will take my nice clean 10 MHz
reference?
Ultimately, I'm looking at output frequencies in single digit GHz, but
something that can be mixed/multiplied up will work just fine.
I'm looking for something that is off the shelf-ey as much as possible.
Using surplus gear is ok, because I really only need 3 or 4 channels and
that might be scroungeable, but spending hours wiring up weird adapters
or locating connectors that haven't been made since 1943 is something
I'd like to avoid.
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--
"The power of accurate observation is commonly called cynicism by those
who
have not got it."
-George Bernard Shaw
Dr. Don Latham AJ7LL
Six Mile Systems LLC
17850 Six Mile Road
Huson, MT, 59846
mail: POBox 404
Frenchtown MT 59834-0404
VOX 406-626-4304
Skype: buffler2
www.lightningforensics.com
www.sixmilesystems.com
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