Bruce Griffiths wrote:
michael taylor wrote:
You have made similar comments about I believe the same approach in
the past. I was wondering if you have ever sketched out a schematic,
even if only rough. Perhaps with a few suggested components to try
(i.e. DAC, Op-Amp) that would be a good
Thanks, Bruce, for the circuit. I don't recognize the transformer
numbers in your schematic. Can you tell us more about the nature of the
transformers you have specified?
Bruce Griffiths wrote:
George
The circuit schematic for a BJT version of the JFET frequency is attached.
The biasing is
Rex wrote:
Thanks, Bruce, for the circuit. I don't recognize the transformer
numbers in your schematic. Can you tell us more about the nature of the
transformers you have specified?
Rex
These are standard Minicircuits through hole mount RF transformers that
have (with an appropriate
Thanks. Great! Commonly available part.. I agree one part for both is good.
Bruce Griffiths wrote:
Rex wrote:
Thanks, Bruce, for the circuit. I don't recognize the transformer
numbers in your schematic. Can you tell us more about the nature of the
transformers you have specified?
From: bg [EMAIL PROTECTED]
Subject: Re: [time-nuts] need recomendation for a portable 10mhz reference
oscilator
Date: Wed, 12 Dec 2007 06:58:15 +0100
Message-ID: [EMAIL PROTECTED]
On Tue, 2007-12-11 at 18:38 -0500, John Ackermann N8UR wrote:
To get decent (for some definition of decent)
Rex wrote:
Thanks. Great! Commonly available part.. I agree one part for both is good.
Rex
One caveat is the dc current flowing in the output transformer may cause
too much distortion (actual specification on the data sheet is somewhat
unclear/ambiguous), in which case capacitively
Hi Bruce,
Fine, you don't like the words far better performance... okay ;-)
you do recognize the small advantage in noise but
gave no relevance to the other aspects namely the
lock acquisition, the fact that I can monitor the jitter over time
etc. (all of them were contained in my word
Luis Cupido wrote:
Hi Bruce,
Fine, you don't like the words far better performance... okay ;-)
you do recognize the small advantage in noise but
gave no relevance to the other aspects namely the
lock acquisition, the fact that I can monitor the jitter over time
etc. (all of them were
I have started to see this 5mhz frequency quartz oscilators that are
really inexpensive (see http://www.alltronics.com/cgi-bin/
category.cgi?item=04P010 ). My question, how would you get this to
work with ntpd? Seems like it work great for my situation where I can
just put inside the rack
Bruce,
I've used plenty of CPLDs but see no reason to use one when it isnt
necessary.
The sentence in my perspective sounds a bit like this:
I've used plenty of TTL and CMOS but see no reason to use them
when I could fit them all on a CPLD.
I do understand that some may not want to get into
On Dec 12, 2007 7:33 AM, Luis Cupido [EMAIL PROTECTED] wrote:
Very good, I do respect the usage of a bunch of CMOS/TTL chips if
someone doesn't want to spend the
effort of learning how to use a CPLD. When it comes to use CPUs for
tasks better done by straight logic (and there are many examples
Bruce Griffiths wrote:
Do you also want a circuit for a sawtooth corrector using one of the
Maxim/Dallas programmable delay lines?
Yes! I now feel inspired to go spin a design after studying all of
these messages in this
thread. My only constraint is that the parts have to pass the
http://www.wired.com/science/discoveries/news/2007/12/time_hackers
73 Alberto I2PHD
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Keith E. Brandt, M.D. wrote:
As a relative newbie to the who time-nut scene, I'm still working on
the big picture of how all the hardware fits together. I've
successfully put together a FreeBSD box with a Garmin 18 LVC as an NTP
server and am getting consistent microsecond
Luis Cupido wrote:
Bruce,
No analog filtering of the D flipflop output is required.
Now you got me lost.
We were talking about a GPSDO, that is locking
an VCXO on the GPS time (1pps or else)
So by the end of it you need an analog
signal to control the voltage input of the VCXO. Right ?
John,
That's a good start towards answering my question. Given my set-up of
GPS referenced NTP server, how would I integrate a frequency
reference into the system?
Keith
As a relative newbie to the who time-nut scene, I'm still working on
the big picture of how all the hardware fits
Scott Burris wrote:
Bruce Griffiths wrote:
Do you also want a circuit for a sawtooth corrector using one of the
Maxim/Dallas programmable delay lines?
Yes! I now feel inspired to go spin a design after studying all of
these messages in this
thread. My only constraint is
Keith E. Brandt, M.D. wrote:
John,
That's a good start towards answering my question. Given my set-up of
GPS referenced NTP server, how would I integrate a frequency
reference into the system?
You'd replace the crystal oscillator on the motherboard with a more
stable reference. The TAPR
In a message dated 12/11/2007 22:00:37 Pacific Standard Time,
[EMAIL PROTECTED] writes:
I am surprised surveying mode is needed anymore. In a SA environment it
makes sense, but for me its hard to understand with the current accuracy
given by the GPS system.
--
Björn
Hi Bjoern,
Scott Burris wrote:
Yes! I now feel inspired to go spin a design after studying all of
these messages in this
thread. My only constraint is that the parts have to pass the Digikey
test, i.e. I have to
be able to order small quantities from Digikey, Mouser, or the like.
It's nearly
Hi Said and All
I have been following this thread with a lot of interest because my
application is also in portable Microwave operations with narrowband modes
such as WSJT. The main issue here is not so much long term frequency
stability as one only has to find a signal in an SSB passband, but
In a message dated 12/12/2007 14:11:50 Pacific Standard Time,
[EMAIL PROTECTED] writes:
Now I am not sure which of any of the above points are necessary or
important but I would be grateful for the thoughts of others.
Regards Rex VK7MO
Hi Rex,
that's a lot of great information!
Rex Moncur wrote:
Hi Said and All
I have been following this thread with a lot of interest because my
application is also in portable Microwave operations with narrowband modes
such as WSJT. The main issue here is not so much long term frequency
stability as one only has to find a signal in
Bruce Griffiths wrote:
As far as I know Dallas/Maxim appears to be the only source of suitable
affordable programmable delay chips for this particular application.
In principle one could use a tapped chain of gates in a CPLD, however
continuous calibration of the delay is required (a delay
Hi Michael,
Yes that may be true (but I did not test any of that...)
Well... with digital prog. logic devices that operate
at similar speed than HC and AC should be true yes.
On the fast CPLDs that run past 300MHz the jitter
should have scale down proportionally (I imagine)
but I have no clue if
Ok. I understand now what you suggest.
Thanks for the explanation.
Luis Cupido.
ct1dmk.
Bruce Griffiths wrote:
Luis Cupido wrote:
Bruce,
No analog filtering of the D flipflop output is required.
Now you got me lost.
We were talking about a GPSDO, that is locking
an VCXO on the GPS
Scott
Scott Burris wrote:
Bruce Griffiths wrote:
As far as I know Dallas/Maxim appears to be the only source of suitable
affordable programmable delay chips for this particular application.
In principle one could use a tapped chain of gates in a CPLD, however
continuous calibration of the
I'm sure you all noticed, SVN37 (PRN07) went offline today. I tracked
it yesterday afternoon, but it is gone today:
http://www.mock.com/test/z3801a/
Looks like it might be gone for good, now we only have 29 GPS satellites
online...
ftp://tycho.usno.navy.mil/pub/gps/gps.txt
jeff
Scott
Data delay devices (http://www.datadelay.com) also do programmable delay
lines their minimum order is $US75 which isnt too bad particularly if
more than one sawtooth corrector is to be built.
They even do ECL programmable delays as do Micrel (http://www.micrel.com).
However these ECL
On Dec 12, 2007 2:32 AM, Bruce Griffiths [EMAIL PROTECTED] wrote:
Michael
The analog circuitry for a sigma-delta DAC is attached.
The input is optically isolated using a high speed low jitter CMOS
optocoupler (Avago produce an equivalent device) to break low frequency
ground loops.
I was
On Dec 12, 2007 8:55 PM, Jeff Mock [EMAIL PROTECTED] wrote:
I'm sure you all noticed, SVN37 (PRN07) went offline today. I tracked
it yesterday afternoon, but it is gone today:
http://www.mock.com/test/z3801a/
Looks like it might be gone for good, now we only have 29 GPS satellites
Michael
michael taylor wrote:
On Dec 12, 2007 2:32 AM, Bruce Griffiths [EMAIL PROTECTED] wrote:
Michael
The analog circuitry for a sigma-delta DAC is attached.
The input is optically isolated using a high speed low jitter CMOS
optocoupler (Avago produce an equivalent device) to break low
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