[time-nuts] GPSDO Alternatives
lists at rtty.us
Wed Dec 5 17:31:02 UTC 2012
If the intent is to come up with something in the same league as the TBolt
there are a few other things you will need:
1) Something to compare the two pps signals to within 0.1 ns.
2) A large amount of code on the control processor (there are a multitude of
special cases ...)
3) A large amount of code on a PC to monitor it and control it (like Lady
4) A set of standards to compare it to while you train and debug it
5) The test gear to collect and analyze the comparison and debug data with
(you will have many months of data)
6) Some sort of control over the feature list. The complexity of 2-5 will go
up significantly each time a nice to have thing is added.
Once you get past step one, the rest of that list dwarf's anything like
which D/A to use. I'm not at all saying it can't be done. Only that the bulk
of the effort starts after you have the hardware.
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of Jim Lux
Sent: Wednesday, December 05, 2012 7:58 AM
To: time-nuts at febo.com
Subject: Re: [time-nuts] GPSDO Alternatives
On 12/5/12 12:06 AM, Bruce Griffiths wrote:
> Hal Murray wrote:
>> albertson.chris at gmail.com said:
>>> What is the simplest phase detecter that could work? I think only
>>> that, and
>>> then a duouble oven crystal from eBay, a GPS and and Arduido.
>> You also need a good D2A to drive the EFC on the osc.
> A synchronous filter of a suitably level translated (CMOS analog switch
> plus low noise reference) PWM output should work well.
True.. but I think the OP was wanting something that doesn't require
designing a circuit and building it.
So what you really want is a high performance DAC on a Arduino shield,
or, alternately, a high performance DAC on a cheap eval board that you
can easily hook up to an Ardino type processor.
This is a bit trickier..
Lots of ADC stuff out there, not so much DAC stuff.
seems to have a number of approaches. Adafruit has a shield with a
Microchip MCP4921 12 bit serial dac
here's a 16 bit solution http://www.shaduzlabs.com/article-12.html but
it's a "build it yourself" solution.
If you're not size/mass/power constrained, you might be able to find an
inexpensive used programmable power supply. I do this using a Prologix
controller driving Agilent E3646 power supplies.. Big, Expensive, etc.
but it does work.
>>> Yes the Aruino is expensive compared to a bare uP chip but using one,
>>> I thin
>>> you could build a GPSDO without a PCB and the Arduino's USB
>>> connection could
>>> be usful for power and logging/control.
>> I wouldn't want to power a GPSDO from USB. It will get power cycled
>> time I need to work on the logging PC. Besides, you only get 2.5
>> watts. The
>> oven will probably take more than that during warm-up.
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to
> and follow the instructions there.
time-nuts mailing list -- time-nuts at febo.com
To unsubscribe, go to
and follow the instructions there.
More information about the time-nuts