Tom,
It looks like they have a pForth interpreter running in there under
PSOS: http://code.google.com/p/pforth/. Is there a mechanism to switch
from SCPI to the Forth interpreter?
david
Trimble and HP took different approaches on their GPSDO's.
Trimble lets you get into things and fiddle
Dale -
To your question re BPSK and DPSK. In both modes the phase shift is 180
degrees.
Straight PSK has the issue of determining the 1's from the 0's, at the
receiver as there is
no phase reference.
To avoid this DPSK encodes the the serial data stream prior to the
bi-phase modulator.
As I
And don't forget those NTP people. BTW, is there an NTP packet exchange
example? That is, what is the typical conversation between an NTP server
and a client?
On Mon, Oct 22, 2012 at 7:28 AM, Hal Murray hmur...@megapathdsl.net wrote:
t...@leapsecond.com said:
BTW, the best time frequency
I already have a number of time-nuts related wiki pages on my site, anybody is
welcome to start a new one. It is open to anyone.
Didier KO4BB
www.ko4bb.com
Sent from my Droid Razr 4G LTE wireless tracker.
-Original Message-
From: David J Taylor david-tay...@blueyonder.co.uk
To:
Tom
I have two questions what should the range, resolution and stability of
the delay generator be and how much do you think a digital loop driven by a
Tbolt would degrade short and medium precision. What is your definition of
short and medium?
Bert Kehren
In a message dated 10/22/2012
I very much agree with this. It works because OCXO thermal effects you're
looking at are in a domain where GPS is able to provide an adequate reference
against which to measure.
Where this scheme doesn't work is with short-term OCXO noise or thermal
transients (GPS isn't a stable enough
Hi Bert,
Not sure about the range/resolution. That would depend on how the standard is
used and what its frequency drift rate is. The stability doesn't have to be too
much better than the standard itself.
The Austron 2055 resolution is 1e-14, IIRC. The Symmetricom AOG is 1e-19
(overkill).
The hump is the DAC update frequency measure: fast update - hump towards
the left, slow update - towards the right. Better update fast or slow:
recently it was pointed out that fast should be better and this will shift
the hump in the 1 to 10 seconds range.
On Mon, Oct 22, 2012 at 1:32 PM, Tom
Paul,
I would also be interested in how you built your simulator.
I'm considering building a simple one myself.
I'll probably have mine just toggle the phase every 100 ms initially.
Dale
-Original Message-
From: paul swed
Sent: Sunday, October 21, 2012 11:08 PM
To: Discussion of
Tom
A good place to start is with a manual of the Austron 2055 delay if there
is real interest. Does any one have it in PDF form?
As to the disciplining a Rb or specifically a HP5065A, the filter part is
the challenge. Having worked on it for the last ten years always using
Brooks loop and
Dear Azelio,
Count on me for that. I am doing my thesis in network synchronization and NTP
will be the main course. I will be posting a brief of the thesis and all
related information in my soon to be published web page. I dream NTP now…
Regards,
Edgardo Molina
Dirección IPTEL
azelio.bori...@screen.it said:
And don't forget those NTP people. BTW, is there an NTP packet exchange
example? That is, what is the typical conversation between an NTP server
and a client?
What are you looking for?
The wikipedia page is a good introduction:
(( replied at beginning to be consistent with this thread ))
Thanks, this has done a good job at furthering my understanding about
error (one way of describing adev as I understand) vs short and long
tau times. I don't have anything to add on that subject, but but I have
a question about a page
t...@leapsecond.com said:
I should also mention the choice to have John Ackermann host the list (free)
along with all the TAPR mailing lists has proven itself again and again. Few
entities on the web have been this solid for a decade. A couple of times a
year we have trouble with S/N ratio,
Hi
One simple / dirty approach, assuming you are starting from 5 or 10 MHz:
Lock up a VCXO at 100 MHz from the source via a wide band PLL. Divide it
down to 1 pps by the usual techniques. Slip the counter (add / subtract one
count) to get things within 10 ns.
Now all you need is a +/- 5 ns
There's a history to many of the GPSDO products you hear us talk about.
I believe the original TBolt (fancy red case) did have an OCXO but it wasn't
particularly high quality. Perhaps Bob can shed light on this.
99% of TBolt's found on the surplus market today, and all the ones in the TAPR
Hi
Based on Time Nuts data - The OCXO's in the TBolt's have indeed gotten
better over the years. The early Piezo labeled parts did not do as well as
the later Trimble labeled parts. With the Trimble labeled parts, roughly
pre-2002 is a break point for performance.
Bob
-Original
On Mon, Oct 22, 2012 at 02:16:19AM -0400, johncr...@aol.com wrote:
Dale -
To your question re BPSK and DPSK. In both modes the phase shift is 180
degrees.
Straight PSK has the issue of determining the 1's from the 0's, at the
receiver as there is
no phase reference.
To avoid this DPSK
On 22 Oct, 2012, at 12:48 , Bob Camp li...@rtty.us wrote:
The big bucks approach probably is to run a good RF ADC on the input and
then do all the offset stuff as DSP math. The VCXO just sits at it's magic
frequency and never moves. More money / no pops.
A somewhat cheaper way might be to
Hi
The gotcha with the DDS is phase truncation. That pretty much trashes the
ADEV.
Bob
-Original Message-
From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On
Behalf Of Dennis Ferguson
Sent: Monday, October 22, 2012 1:44 PM
To: Discussion of precise time and frequency
On Mon, Oct 22, 2012 at 1:00 PM, Tom Van Baak t...@leapsecond.com wrote:
There's a history to many of the GPSDO products you hear us talk about.
I believe the original TBolt (fancy red case) did have an OCXO but it
wasn't particularly high quality. Perhaps Bob can shed light on this.
99% of
Yes, the problem is that I don't have anything running NTP... I'm searching
for a packet dump: I should use it to quickly develop the response for a
possible Lantronix XPort implementation.
On Mon, Oct 22, 2012 at 6:22 PM, Hal Murray hmur...@megapathdsl.net wrote:
azelio.bori...@screen.it
On 10/22/2012 07:13 AM, Tom Van Baak wrote:
Trimble and HP took different approaches on their GPSDO's.
Trimble lets you get into things and fiddle around. HP is much more a black box.
I have never seen anything that lets you fiddle' with one of the HP units.
Hi Bob,
I'm glad you asked. True,
Bert,
On 10/22/2012 04:46 PM, ewkeh...@aol.com wrote:
Tom
A good place to start is with a manual of the Austron 2055 delay if there
is real interest. Does any one have it in PDF form?
As to the disciplining a Rb or specifically a HP5065A, the filter part is
the challenge. Having worked on it
On 10/22/2012 07:53 PM, Bob Camp wrote:
Hi
The gotcha with the DDS is phase truncation. That pretty much trashes the
ADEV.
True, but the more bits you apply the better performance you get.
Modern DDS clock chips do have pretty amazing specs for the money you spend.
Cheers,
Magnus
David,
On 10/22/2012 08:07 AM, David Hooke wrote:
Tom,
It looks like they have a pForth interpreter running in there under
PSOS: http://code.google.com/p/pforth/.
That's not the pForth implementation in there I beleive.
It's pretty close thought.
Is there a mechanism to switch from SCPI to
Magnus
Are you changing or did you change and if you are how much time do you
have.
Bert
In a message dated 10/22/2012 6:24:06 P.M. Eastern Daylight Time,
mag...@rubidium.dyndns.org writes:
Bert,
On 10/22/2012 04:46 PM, ewkeh...@aol.com wrote:
Tom
A good place to start is with a
Hi
Modern parts are pretty cool. I have measured them them for this application.
The truncation still is a big issue.
Bob
On Oct 22, 2012, at 6:16 PM, Magnus Danielson mag...@rubidium.dyndns.org
wrote:
On 10/22/2012 07:53 PM, Bob Camp wrote:
Hi
The gotcha with the DDS is phase
Warren,
On 10/23/2012 12:45 AM, WarrenS wrote:
Tom said:
In general, when you discipline a OCXO you get that characteristic ADEV
hump.
At some point there is a cross-over and you know/assume that at that
point
each must be contributing 1/sqrt(2) of the noise.
Although putting the Hump at
On 10/23/2012 12:41 AM, Bob Camp wrote:
Hi
Modern parts are pretty cool. I have measured them them for this application.
The truncation still is a big issue.
If you generate a lower frequency and gear it up in frequency, you would
get better result. It's more or less what the phase
Hi
Yes, a DDS at high freq./ narrow band crystal filter / divide to low audio /
image reject mix with input back to rf / lock to VCXO approach would get around
much (but not quite all) of the truncation stuff. It's complex enough that I
suspect that ADC approach would give it a run for the
Dale I guess a couple of comments to you and everyone. I am not an expert
on the chip. I downloaded what was available and thats not all that much.
So if someone has the experience to know whats actually correct and how to
turn this magical 20 cent chip into something useful, I am all ready to
- Original Message -
From: paul swed paulsw...@gmail.com
To: Discussion of precise time and frequency measurement
time-nuts@febo.com
Sent: Monday, October 22, 2012 8:35 PM
Subject: Re: [time-nuts] WWVB New Modulation five cent demodulator / carrier
regenerator ?
To switch
I was giving it 1000uv. Thats why I say it needs a lot.
On Mon, Oct 22, 2012 at 9:00 PM, Tom Miller tmil...@skylinenet.net wrote:
- Original Message - From: paul swed paulsw...@gmail.com
To: Discussion of precise time and frequency measurement
time-nuts@febo.com
Sent: Monday,
34 matches
Mail list logo
