On 09/27/2013 12:53 PM, Charles Steinmetz wrote:
Tom wrote:
One of my first applications is to use a 10MHz output to phaselock a
VCXO master clock in a radio transceiver. * * * Next I went to
IDT to find the best logic buffer I could find. I am looking at the
IDT 74FCT38072 2 channel
Hi Bob,
On 09/27/2013 01:44 PM, Bob Camp wrote:
Hi
Rise and fall times are not the thing to worry about on the gates. Look at
the propagation delay. That's what will vary.
On Sep 27, 2013, at 2:11 AM, Tom Minnis tom_min...@att.net wrote:
Thanks for all your thoughts on the subject.
Hi Tom,
The Jackson CSAC GPSDO solution has a vcxo-based noise filter pll on the pcb,
improving the noise performance and removing spurs as well over just the CSAC
by itself so the specs will be quite different.
In fact the LN CSAC version of that board achieves around -100dBc/Hz at one Hz,
On 09/26/2013 08:25 PM, Tom Knox wrote:
It seems you would need to think of the Pulsar as the clock behind the GPS
sat. You then have an algorithm to add the other need information at the rec
end. To make things easier add to the constellation one master clock signal
with corrections and
On 9/28/13 4:14 AM, Magnus Danielson wrote:
On 09/26/2013 08:25 PM, Tom Knox wrote:
It seems you would need to think of the Pulsar as the clock behind the GPS sat.
You then have an algorithm to add the other need information at the rec end. To
make things easier add to the constellation one
Hi
WWVB is at 60 KHz. If you have a radio that will tune down there and an
antenna, you're set up. Things like wall clocks and wrist watches have
miniature receivers in them that pull timing off of WWVB, so that's an option
for parts if you aren't set up already.
WWB puts out a time code as
On 09/28/2013 01:42 PM, Jim Lux wrote:
On 9/28/13 4:14 AM, Magnus Danielson wrote:
On 09/26/2013 08:25 PM, Tom Knox wrote:
It seems you would need to think of the Pulsar as the clock behind
the GPS sat. You then have an algorithm to add the other need
information at the rec end. To make
Don't forget the Doppler and relativistic effects of the earth moving
around the solar system barycenter. But that's not much different
than you do for GPS (e.g. knowing satellite orbits, etc.)
Naturally. You also needs to compensate for their decay-rate as you try
to span longer periods.
As always, be careful with the hard and fast rules. Most crystal oscillators
generate sine waves first, but if the oscillator is part of a GPSDO, it will
have to be converted to square to be processed by the logic within the GPSDO,
so even if the device has a sine output, there will be a square
On 09/28/2013 02:15 PM, Jim Lux wrote:
Don't forget the Doppler and relativistic effects of the earth moving
around the solar system barycenter. But that's not much different
than you do for GPS (e.g. knowing satellite orbits, etc.)
Naturally. You also needs to compensate for their
jim...@earthlink.net said:
Scrolling down, it looks like they're getting a whopping 0.5 dB SNR on
the Crab Nebula pulsar.
How much of the noise comes from local sources vs thermal or galactic?
I'm missing the scale factor for the big picture. How big a volume does this
work over before I
I've actually got my GPSDO in one of these, but there's no ventilation for
cooling, so I thought I'd look for something else for the Rb standard.
Bob
From: Collins, Graham coll...@navcanada.ca
To: Discussion of precise time and frequency measurement
On 9/28/13 7:32 AM, Hal Murray wrote:
jim...@earthlink.net said:
Scrolling down, it looks like they're getting a whopping 0.5 dB SNR on
the Crab Nebula pulsar.
How much of the noise comes from local sources vs thermal or galactic?
These are amateurs, so they're probably not using
A couple of points:
Pulsars are pretty faint and the only solution to that is antenna
aperture. We looked at that while doing SETI a ways back. Receivers are
now quite close to the theoretical limit as far as noise temperatuse.
There is very little room for improvement.
Pulsars are not
Pulsars are not infrinitely stable. They slowly decay, and, worse,
randomly undergto 'star quakes' which upset their timing. This was proven
in the 1960s.
John,
You are correct, but it is a simple opportunity rather than a major problem.
The solution is to monitor multiple pulsar sources.
I am just thinking out loud on this, But it seems you could use carrier phase
from plain star light since the light spectrum from stars have spikes and
notches which are constant and using the same concept as the Hubble Constant a
spacecraft could determine speed, direction, and position. Like
Yes, but to use them for interstellar navigation, as suggested, when the
propagation delays are 10,000 years or more complicates things.
What is contemplated is comparing the clocks, as they were thousands of
years ago, where they were thousands of years ago, with largely unknown
motions. You
On 09/28/2013 02:24 PM, Didier Juges wrote:
As always, be careful with the hard and fast rules. Most crystal oscillators
generate sine waves first, but if the oscillator is part of a GPSDO, it will
have to be converted to square to be processed by the logic within the GPSDO,
so even if the
Hi Tom,
On 09/28/2013 07:49 PM, Tom Knox wrote:
I am just thinking out loud on this, But it seems you could use carrier phase
from plain star light since the light spectrum from stars have spikes and
notches which are constant and using the same concept as the Hubble Constant
a spacecraft
Hi
If we're talking about a basement TimeNut setup there are some things that
matter and some things that really don't:
Matters:
Load isolation matters. You can get 45 degrees ( 12 ns) quite easily
with a load change
ADEV matters. Your frequency counter will not be happy with
Just to satisfy my curiosity: what's easiest to detect galactic pulse emitter
(regardless of type), and what's the minimum setup to reliably look at it,
whether it's just during night time, or whatever. Just seeking perspective, I
haven't just won the lottery.
Bob
Hi
If you are on the surface of the earth, you face the sun from time to time.
That creates some issues that you would not have in a deep space setting. In
deep space you don't have to correct for all sorts of orbital issues as well.
This is one of those - not so easy here - sort of things.
From what I remember, with the 1000' Aricebo dish and pretty good LNA,
there were a literal handful of RF photons per pulse... less than 10
maybe.
-John
===
Just to satisfy my curiosity: what's easiest to detect galactic pulse
emitter (regardless of type), and what's the
The sune is hugely bright in the RF.
I've been able to see it at 2.2 GHz with nothing more than a horn a foot
or so across and a receiver w/ a NF of maybe 8 dB (cavity preselector
mixer IFA... ACL SR-209).
There was a noticable difference between pointing at the sun and in
another direction.
On 9/28/13 3:55 PM, Bob Stewart wrote:
Just to satisfy my curiosity: what's easiest to detect galactic pulse emitter
(regardless of type), and what's the minimum setup to reliably look at it,
whether it's just during night time, or whatever. Just seeking perspective, I
haven't just won the
Thanks to all respondents. Perspective is a hard thing to find in this group.
=)
Bob
From: Jim Lux jim...@earthlink.net
To: time-nuts@febo.com
Sent: Saturday, September 28, 2013 6:33 PM
Subject: Re: [time-nuts] Pulsars make a GPS for the cosmos
On
There is actually little at 1421MHz from the sun the radiation from the sun
is black body radiation 1421 is an electron flip more likely in isolated
molecules (the sun is plasma not gas) or Hydrogen masers. We set up 12Ghz
sat LNBs a couple of weekends ago to try and stimulate some school
On Sun, Sep 29, 2013 at 6:55 AM, Bob Stewart b...@evoria.net wrote:
I haven't just won the lottery.
Yet. You left out the yet.
--
Sanjeev Gupta
+65 98551208 http://www.linkedin.com/in/ghane
___
time-nuts mailing list -- time-nuts@febo.com
To
There's no yet to it. I don't play. =)
From: Sanjeev Gupta gha...@gmail.com
To: Bob Stewart b...@evoria.net; Discussion of precise time and frequency
measurement time-nuts@febo.com
Sent: Saturday, September 28, 2013 10:13 PM
Subject: Re: [time-nuts]
b...@evoria.net said:
Just to satisfy my curiosity: what's easiest to detect galactic pulse
emitter (regardless of type), and what's the minimum setup to reliably look
at it, whether it's just during night time, or whatever. Just seeking
perspective, I haven't just won the lottery.
An
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