Hi
Quebec Hydro and I suspect others use it to regulate power generation
facilities. Keeps them from simply cross feeding power through the reactance of
the distribution network. They have some pretty long lines between source and
load
Bob
On Sep 11, 2010, at 10:53 PM, Brian Kirby
jees, Bob, it's called a TDR
- Original Message -
From: Bob Camp li...@rtty.us
To: Discussion of precise time and frequency measurement
time-nuts@febo.com
Sent: Friday, September 10, 2010 9:27 PM
Subject: Re: [time-nuts] Timing Distribution in Mountainous Terrain
Hi
The assumption
jim...@earthlink.net said:
I seem to recall that the returned beam divergence was no narrower than the
incident beam divergence, so if you want a X km footprint on Earth, you
need a X km footprint on the Moon.
Please let me know if you find that again.
I poked around on the web and can't
On 09/10/2010 11:50 PM, jimlux wrote:
Ralph Smith wrote:
OK, stop me if this is really stupid. The initial site is in Colorado.
Would it be possible to use WWV? In particular:
1) Lock a reference to the carrier of one of the WWV signals
2) Generate PPS off of WWV-locked reference
3)
On 09/10/2010 07:17 AM, jimlux wrote:
Ralph Smith wrote:
On Sep 9, 2010, at 8:01 PM, Rick Karlquist wrote:
I would like to point out that the environmental sensitivities of
the 5071A are unmeasureable, and the measurement threshold is
far below 5.8E-14. I would estimate that the 5071A (and
It is my understanding that test equipment is exempt from all
RoHS requirements.
-Chuck Harris
Magnus Danielson wrote:
Commercial availability is somewhat limited. A problem with Hg ion traps
would be ROHS, unless they can be exempted or assumed to be within the
telco exempt, which would be
Don Latham wrote:
jees, Bob, it's called a TDR
- Original Message - From: Bob Camp li...@rtty.us
To: Discussion of precise time and frequency measurement
time-nuts@febo.com
Sent: Friday, September 10, 2010 9:27 PM
Subject: Re: [time-nuts] Timing Distribution in Mountainous Terrain
If it's far enough in the future.. Hg ion traps have a lot of
potential.. smaller, lower power, etc. than Cs
Commercial availability is somewhat limited.
that's for sure.. I think all the Hg ion traps are still laboratory
curiosities.. but, 10 years from now?
A problem with Hg ion
On 09/11/2010 05:29 PM, jimlux wrote:
If it's far enough in the future.. Hg ion traps have a lot of
potential.. smaller, lower power, etc. than Cs
Commercial availability is somewhat limited.
that's for sure.. I think all the Hg ion traps are still laboratory
curiosities.. but, 10 years from
On Sep 11, 2010, at 12:13 PM, Magnus Danielson wrote:
On 09/11/2010 05:29 PM, jimlux wrote:
If it's far enough in the future.. Hg ion traps have a lot of
potential.. smaller, lower power, etc. than Cs
Commercial availability is somewhat limited.
that's for sure.. I think all the Hg ion
Sites communicate via landline telco. If there are sufficient mutually
visible networked sites to form a solution on an aircraft visible to
stations not in the timing network that would work, and is one of the
options we are studying.
May it be assumed that the sites are on the regular
In message 8459b572-1428-4f6a-8375-afb4f7225...@cox.net, Thomas A. Frank wr
ites:
If so, being within 300 miles of each other suggests that they are
most likely all on the SAME section of the grid, in which case the
phase time of arrival of the electric power waveform should be
constant
On 09/11/2010 08:24 PM, Ralph Smith wrote:
On Sep 11, 2010, at 12:13 PM, Magnus Danielson wrote:
On 09/11/2010 05:29 PM, jimlux wrote:
If it's far enough in the future.. Hg ion traps have a lot of
potential.. smaller, lower power, etc. than Cs
Commercial availability is somewhat limited.
Hi
You also have load dependent harmonic energy on there that messes up the zero
crossings at the micro second level.
Bob
On Sep 11, 2010, at 3:45 PM, Poul-Henning Kamp p...@phk.freebsd.dk wrote:
In message 8459b572-1428-4f6a-8375-afb4f7225...@cox.net, Thomas A. Frank
wr
ites:
If so,
On 09/11/2010 11:08 PM, Bob Camp wrote:
Hi
You also have load dependent harmonic energy on there that messes up the zero
crossings at the micro second level.
Not to speak about the highly shifting reactive load, which can shift
both negative and positive... and mess about the transitions.
If the odd harmonics were filtered out, would the zero crossing of the
60 (50) Hz fundamental
be stable enough ?
Thanks Stan,W1LE Cape Cod FN41sr
On 9/11/2010 5:08 PM, Bob Camp wrote:
Hi
You also have load dependent harmonic energy on there that messes up the zero
Hi
Since the harmonics are locally generated, each site will see different
crossings. The same is true of the local load impedance.
Bob
On Sep 11, 2010, at 5:54 PM, Stan, W1LE stanw...@verizon.net wrote:
If the odd harmonics were filtered out, would the zero crossing of the 60
(50) Hz
Stan, W1LE wrote:
If the odd harmonics were filtered out, would the zero crossing of the
60 (50) Hz fundamental
be stable enough ?
not to 30 ns grin
Interestingly, one of the markets that Symmetricom/TrueTime/Datum sells
into is GPS disciplined receivers used for power control. Power
I believe the primary reasons for GPS receivers for the power industry
is power line fault location. They use time tagging to measure
disturbances to locate a fault and it's accuracy directly determines its
resolution.
On 9/11/2010 7:33 PM, jimlux wrote:
Stan, W1LE wrote:
If the odd
Each pair of sites could maybe do two-way time transfer over VHF or
UHF meteor scatter. I don't know what the achievable resolution might
be; I suppose it would depend on the size of the scattering entity
(plasma cloud) and its geometry relative to the two sites. Sparse and
unpredictable
-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf
Of jimlux
Sent: 10 September 2010 06:14
To: rich...@karlquist.com; Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Timing Distribution in Mountainous Terrain
Rick Karlquist wrote:
I would like to point
Aren't pulsars a reliable accurate time source or do they not provide the
30nS over ten days accuracy?
By using them in common view, though, any absolute error would drop
out. I'm not sure pulsar pulses are fast enough to do discrimination
at 30 ns time scales, though. VLBI with broadband
Satellite laser ranging using LAGEOS and friends?
On second thought, this wouldn't work anyway (besides being too
expensive)---stations would have to be very close together to have
common view.
Cheers,
Peter Monta
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time and frequency measurement
Subject: Re: [time-nuts] Timing Distribution in Mountainous Terrain
Loran?
What was the stability of Loran when used to distribute time? (I'm assuming
I can use something like GPS for calibration.)
Wikipedia says:
The absolute accuracy of LORAN-C varies from 0.10
On Sep 10, 2010, at 7:50 AM, J. L. Trantham wrote:
Loran was used as an area navigation method in aviation for many years. It
was available nation wide with a number of chains. I had assumed that the
area of interest was the Rocky's but if the Appalachians, even better.
The site currently
Hi
Satellites appear to be out. Best case, pulsars would be a once a day thing.
You would need a bit better than 30 ns on the transfer (10?) to get the system
to perform.
To put an order of magnitude on the difficulty:
I believe that 20 ns is in the same range as the error national standards
Peter Monta wrote:
Aren't pulsars a reliable accurate time source or do they not provide the 30nS
over ten days accuracy?
By using them in common view, though, any absolute error would drop
out. I'm not sure pulsar pulses are fast enough to do discrimination
at 30 ns time scales, though.
On Fri, September 10, 2010 11:43 am, Mark Spencer wrote:
The application in question seems to be concerned with the realitive time
difference between sites as opposed to absolute accuracy so depending on
how
close they were together the propgation variances in a loran type solution
may
not
On 9/9/2010 12:49 PM, k6...@comcast.net wrote:
Ralph--
As far as getting a signal through mountainous terrain, look at NVIS antennas
for HF -- we use them for Field Day for just that kind of communications, 200
- 300 miles in mountainous terrain. Figuring out propagation delays is going
I presume that there's a good reason for the selection of antenna sites which
don't have LOS to each other. However, would it be possible to select
additional sites at which to install repeaters to allow timing calibrations to
be made between pairs of primary receiving sites? These repeaters
-Original Message-
From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On
Behalf Of Ralph Smith
Sent: 09 September 2010 5:49 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Timing Distribution in Mountainous Terrain
The network is spread
The application in question seems to be concerned with the realitive time
difference between sites as opposed to absolute accuracy so depending on how
close they were together the propgation variances in a loran type solution
may not be that signficant as they may be common to the a group
On 9/9/2010 2:03 PM, Ralph Smith wrote:
1e-11 only buys you 3000 seconds of drift before blowing the 30 ns budget.
Without going to cesium we will most likely need some form of mutually
visible synchronization.
Is Cesium even enough? The requirement looks like about 6 parts in
10e-14.
On 9/10/2010 7:26 AM, Ralph Smith wrote:
On Sep 10, 2010, at 7:50 AM, J. L. Trantham wrote:
Loran was used as an area navigation method in aviation for many years. It
was available nation wide with a number of chains. I had assumed that the
area of interest was the Rocky's but if the
Hi
An event that totally takes out every single GPS sat probably takes out
everything else in orbit. A single GPS sat, no longer under ground control
would be fine for timing a system like this. You don't need a full
constellation or ground segment steering.
About the only non-end of the
...@nf6x.net
To: Discussion of precise time and frequency measurement time-nuts@febo.com
Sent: Fri, September 10, 2010 11:49:49 AM
Subject: Re: [time-nuts] Timing Distribution in Mountainous Terrain
I presume that there's a good reason for the selection of antenna sites which
don't have LOS to each
Can you use tethered balloons at each site to obtain adequate S/N
in their position to permit time calculations to 30ns uncertainty?
Pete Rawson
On Sep 10, 2010, at 11:07 AM, Oz-in-DFW wrote:
On 9/9/2010 2:03 PM, Ralph Smith wrote:
1e-11 only buys you 3000 seconds of drift before blowing
On Sep 10, 2010, at 10:47 AM, Pete Rawson wrote:
Can you use tethered balloons at each site to obtain adequate S/N
in their position to permit time calculations to 30ns uncertainty?
Tether a single balloon to three sites to reduce the balloon's displacement due
to wind, and then measure its
On 9/10/2010 12:26 PM, Stanley Reynolds wrote:
On the crazy side another common view object is the lunar laser ranging
retroreflector array. Has been improvements in cost of lasers and telescopes
in
the past 41 years and it doesn't appear to be headed for shutdown anytime
soon.
Stanley Reynolds wrote:
On the crazy side another common view object is the lunar laser ranging
retroreflector array. Has been improvements in cost of lasers and telescopes in
the past 41 years and it doesn't appear to be headed for shutdown anytime soon.
Hmm.. the SNR isn't all that huge
Hi
A lunar setup would only give you data for part of the day. You would relax the
flywheel requirement. Net result likely would still be a maser / cesium combo
at each site. Not real clear how you would model clouds and weather into the
availability equation. Some of the things that 100% take
OK, stop me if this is really stupid. The initial site is in Colorado.
Would it be possible to use WWV? In particular:
1) Lock a reference to the carrier of one of the WWV signals
2) Generate PPS off of WWV-locked reference
3) Periodically send difference of GPSDO PPS and WWV-locked PPS home,
Ralph Smith wrote:
OK, stop me if this is really stupid. The initial site is in Colorado.
Would it be possible to use WWV? In particular:
1) Lock a reference to the carrier of one of the WWV signals
2) Generate PPS off of WWV-locked reference
3) Periodically send difference of GPSDO PPS and
First thought is that the doppler shift associated with sky wave propogation
will likely present issues.Wwvb might be a better choice if locking an
oscilator to a received rf carrier will work.
On Fri Sep 10th, 2010 5:04 PM EDT Ralph Smith wrote:
OK, stop me if this is really stupid. The
On 9/10/2010 4:04 PM, Ralph Smith wrote:
OK, stop me if this is really stupid. The initial site is in Colorado.
Would it be possible to use WWV? In particular:
1) Lock a reference to the carrier of one of the WWV signals
2) Generate PPS off of WWV-locked reference
3) Periodically send
[Lunar Laser Ranging]
Hmm.. the SNR isn't all that huge on the echo. The target is say, 1 square
meter, at a distance of 300,000 km.
The beam divergence coming back is about the same as the outbound (that
is, in order to cover 300km on earth, you need to have a spot on the moon
about
ra...@ralphsmith.org said:
There are probably several fatal flaws with this approach. In particular,
the following are required:
1) Ability to maintain constant lock to WWV
2) Common-mode error. Will the propagation from WWV be similar
enough for all stations to it be a practical common
snip
If you have to work with the existing corner cubes, I don't see how to start
with a pulse at one site, bounce it off the moon, and get it back to another
site that isn't nearby.
If you didn't send the pulse it would be hard to time the trip anyway no start
time. But it one site is
Well; maybe more to it. Ballon tether carries a few watts to transmit
from the ballon altitude to all other sites.
At predetermined times the master site balloon transmits to the other
sites. The other sites respond with their estimated time. The master
provides corrected time.
Knowing past
If you didn't send the pulse it would be hard to time the trip anyway no
start time.
If you know the start time and the receive time, you can compute the distance.
If you know the start time and the distance you can compute the receive time
and hence synchronize clocks.
For this discussion,
[mailto:time-nuts-boun...@febo.com]on
Behalf Of Oz-in-DFW
Sent: Friday, September 10, 2010 12:21 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Timing Distribution in Mountainous Terrain
On 9/10/2010 7:26 AM, Ralph Smith wrote:
On Sep 10, 2010, at 7:50 AM, J
-
From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com]on
Behalf Of Oz-in-DFW
Sent: Friday, September 10, 2010 12:21 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Timing Distribution in Mountainous Terrain
On 9/10/2010 7:26 AM, Ralph Smith
measurementtime-nuts@febo.com
Reply-To: Discussion of precise time and frequency measurement
time-nuts@febo.com
Subject: Re: [time-nuts] Timing Distribution in Mountainous Terrain
snip
If you have to work with the existing corner cubes, I don't see how to start
with a pulse at one site, bounce
Hal,
The LORAN frequency was picked to have predominately ground wave acquisition
over
the less preferred skywave. The only signal worth considering from Fort Collins
is the WWVB signal which is at 60 KHz.
For Ralph's application in Colorado, the WWVB signal would probably do it.
Particularly
On Sep 10, 2010, at 7:44 PM, J. L. Trantham, M. D. wrote:
I guess I am thinking about this from a user perspective rather than an
engineering design and implementation perspective. If the requirement is
aircraft separation, LORAN should be adequate for that, if it was still up.
You would
-Original Message-
From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On
Behalf Of Stanley Reynolds
Sent: Friday, September 10, 2010 7:13 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Timing Distribution in Mountainous Terrain
From: J. L. Trantham jlt...@att.net
To: Discussion of precise time and frequency measurement time-nuts@febo.com
Sent: Fri, September 10, 2010 9:09:29 PM
Subject: Re: [time-nuts] Timing Distribution in Mountainous Terrain
-Original Message-
From: time-nuts-boun...@febo.com [mailto:time
] On
Behalf Of Stanley Reynolds
Sent: Friday, September 10, 2010 7:13 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Timing Distribution in Mountainous Terrain
How to keep hundreds of miles of copper stable or predict it's delay ?
Stanley
Would
Hal Murray wrote:
[Lunar Laser Ranging]
Hmm.. the SNR isn't all that huge on the echo. The target is say, 1 square
meter, at a distance of 300,000 km.
The beam divergence coming back is about the same as the outbound (that
is, in order to cover 300km on earth, you need to have a spot on
Stanley Reynolds wrote:
How to keep hundreds of miles of copper stable or predict it's delay ?
Stanley
these days, you'd use optical fiber, but the answer is the same, you
measure it in real time. Send a signal down it and see when the
reflection comes back. Off the shelf hardware these
ground wave has variation due to changes in refractive index over the path.
- Original Message -
From: WB6BNQ wb6...@cox.net
To: Discussion of precise time and frequency measurement
time-nuts@febo.com
Sent: Friday, September 10, 2010 6:46 PM
Subject: Re: [time-nuts] Timing Distribution
Symmetricom makes GPS based NTP time servers with excellent holdover
capability. I think our SyncServer with an OXCO is good for +/- 0.5
second holdover over something like 60 days. They have options for Rb
oscillators installed that will make that much much better and it might fall
inside of
How widely spread is your network?
Sent from my BlackBerry Wireless thingy while I do other things...
-Original Message-
From: Ralph Smith ra...@ralphsmith.org
Sender: time-nuts-boun...@febo.com
Date: Thu, 9 Sep 2010 11:37:46
To: time-nuts@febo.com
Reply-To:
The requirement is 30 nanoseconds, so individual rubidium holdover over
six days won't cut it.
Ralph
On Thu, September 9, 2010 11:58 am, Robert Darlington wrote:
Symmetricom makes GPS based NTP time servers with excellent holdover
capability. I think our SyncServer with an OXCO is good for
The network is spread over about 250-300 US miles.
Ralph
On Thu, September 9, 2010 12:01 pm, Didier Juges wrote:
How widely spread is your network?
Sent from my BlackBerry Wireless thingy while I do other things...
-Original Message-
From: Ralph Smith
On 9/9/2010 8:37 AM, Ralph Smith wrote:
We have a requirement for approximately ten radio sites to be synchronized
to within 30 ns of each other.
30 ns seems a little closer than most radio site applications need...
what drives this requirement?
Ordinarily you could throw in an
appropriate
Sent: Thu, September 9, 2010 11:45:04 AM
Subject: Re: [time-nuts] Timing Distribution in Mountainous Terrain
The requirement is 30 nanoseconds, so individual rubidium holdover over
six days won't cut it.
Ralph
On Thu, September 9, 2010 11:58 am, Robert Darlington wrote:
Symmetricom makes GPS based
] Timing Distribution in Mountainous Terrain
The network is spread over about 250-300 US miles.
Ralph
On Thu, September 9, 2010 12:01 pm, Didier Juges wrote:
How widely spread is your network?
Sent from my BlackBerry Wireless thingy while I do other things
On Thu, September 9, 2010 1:10 pm, Matthew Kaufman wrote:
On 9/9/2010 8:37 AM, Ralph Smith wrote:
We have a requirement for approximately ten radio sites to be
synchronized
to within 30 ns of each other.
30 ns seems a little closer than most radio site applications need...
what drives this
Ralph--
As far as getting a signal through mountainous terrain, look at NVIS antennas
for HF -- we use them for Field Day for just that kind of communications, 200 -
300 miles in mountainous terrain. Figuring out propagation delays is going to
be interesting with NVIS though.
73 de Bob
On 9/9/2010 10:42 AM, Ralph Smith wrote:
On Thu, September 9, 2010 1:10 pm, Matthew Kaufman wrote:
On 9/9/2010 8:37 AM, Ralph Smith wrote:
We have a requirement for approximately ten radio sites to be
synchronized
to within 30 ns of each other.
30 ns seems a little closer than most radio
What about Symmetricom XPRO Rubidium? It says on the data sheet they have a low
aging rate option (1e-11 / month).
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On Sep 9, 2010, at 10:42, Ralph Smith ra...@ralphsmith.org wrote:
Paranoia. People making the requirements are concerned with GPS going away
due to solar flare or some other reason.
Hmm... So the decision makers think that after a solar flare or some other
reason (hostile destruction of the
On Thu, September 9, 2010 1:55 pm, Matthew Kaufman wrote:
On 9/9/2010 10:42 AM, Ralph Smith wrote:
On Thu, September 9, 2010 1:10 pm, Matthew Kaufman wrote:
On 9/9/2010 8:37 AM, Ralph Smith wrote:
We have a requirement for approximately ten radio sites to be
synchronized
to within 30 ns
1e-11 only buys you 3000 seconds of drift before blowing the 30 ns budget.
Without going to cesium we will most likely need some form of mutually
visible synchronization.
Ralph
On Thu, September 9, 2010 2:01 pm, Jason Rabel wrote:
What about Symmetricom XPRO Rubidium? It says on the data sheet
On 9/9/2010 11:57 AM, Ralph Smith wrote:
You're making the mistake of applying logic. ;) Actually, aircraft can
continue to fly VFR or navigate using VOR/DME and inertial navigation.
The radios are part of an ADS-B installation.
Yes, and they can make routine position reports and ATC can
Hmmm...I design such timing systems for Moto data radios, and 30nS sync is
going to be very hard to achieve in reality. Over a few hundred miles you're
going to have OTA time of flight issues, temperature dependencies, etc. Over
the years this has been tried, usually with dismal success in
On Thu, September 9, 2010 3:17 pm, John Anderson wrote:
Hmmm...I design such timing systems for Moto data radios, and 30nS sync is
going to be very hard to achieve in reality. Over a few hundred miles
you're going to have OTA time of flight issues, temperature dependencies,
etc. Over the
1) Your own LORAN?
2) MASERS!
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and follow the instructions there.
I would agree with the many comments.
Loran first choice in europe. Oooops we killed it here.
30ns speed of light issues. Think you need a synchronized RB or CS.
But what on earth needs 30ns in a radio.
On Thu, Sep 9, 2010 at 5:11 PM, Chris Howard ch...@elfpen.com wrote:
1) Your own LORAN?
On Sep 9, 2010, at 12:03 PM, Ralph Smith wrote:
1e-11 only buys you 3000 seconds of drift before blowing the 30 ns budget.
Without going to cesium we will most likely need some form of mutually
visible synchronization.
How about a rubidium or cesium standard at each site for holdover, with an
Ralph,
so you're talking about 5.8E-14, right?
I'd think no off the shelf caesium, even when run in a temperature
controlled environment, will get you there.
Well, at a first glance, a 5071A with high performance tube would, if
you keep any environmental effects out.
So you'll likely need to
Adrian wrote:
Ralph,
so you're talking about 5.8E-14, right?
I'd think no off the shelf caesium, even when run in a temperature
controlled environment, will get you there.
Well, at a first glance, a 5071A with high performance tube would, if
you keep any environmental effects out.
So
See TVB's site for an experiment with moving CS standards around...
Adrian
Ralph,
so you're talking about 5.8E-14, right?
I'd think no off the shelf caesium, even when run in a temperature
controlled environment, will get you there.
Well, at a first glance, a 5071A with high performance
.
- Original Message
From: Hal Murray hmur...@megapathdsl.net
To: Discussion of precise time and frequency measurement time-nuts@febo.com
Sent: Thu, September 9, 2010 2:57:50 PM
Subject: Re: [time-nuts] Timing Distribution in Mountainous Terrain
Neat problem. Please let us know what you finally do
Hi
If 30 ns is the system goal, then you have a lot more to budget for than simple
clock error. You could easily be below 10 ns for just the clock portion of the
budget. I suspect that multiple 5071's and a maser or two at each site will be
the ultimate solution if each must stand alone for 6
Radar calibration:
You could do a clock calibration if you knew some fixed reference
points to
sweep.
Put some towers up on a few of the taller peaks in the area. Measure
them
while the GPS is running and use them for reference to keep the clocks
right when GPS is down.
But masers sound
On Sep 9, 2010, at 9:27 PM, Bob Camp wrote:
Hi
If 30 ns is the system goal, then you have a lot more to budget for than
simple clock error. You could easily be below 10 ns for just the clock
portion of the budget. I suspect that multiple 5071's and a maser or two at
each site will be
On Sep 9, 2010, at 8:01 PM, Rick Karlquist wrote:
I would like to point out that the environmental sensitivities of
the 5071A are unmeasureable, and the measurement threshold is
far below 5.8E-14. I would estimate that the 5071A (and ONLY the 5071A
among commercial clocks) could get the job
way to do this ?
Just a random thought.
- Original Message
From: Hal Murray hmur...@megapathdsl.net
To: Discussion of precise time and frequency measurement time-nuts@febo.com
Sent: Thu, September 9, 2010 2:57:50 PM
Subject: Re: [time-nuts] Timing Distribution in Mountainous Terrain
Loran?
Joe
-Original Message-
From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On
Behalf Of Mark J. Blair
Sent: Thursday, September 09, 2010 1:48 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Timing Distribution in Mountainous
Loran?
What was the stability of Loran when used to distribute time? (I'm assuming
I can use something like GPS for calibration.)
Wikipedia says:
The absolute accuracy of LORAN-C varies from 0.10-0.25-nautical-mile (185-463
m). Repeatable accuracy is much greater, typically from 60-300-foot
On Fri, Sep 10, 2010 at 06:17, Mark J. Blair n...@nf6x.net wrote:
Or, a specially-equipped aircraft which is periodically flown along paths
visible to multiple antenna sites during an extended holdover in order to
adjust out drift based on measured round-trip times between the sites and
Ralph Smith wrote:
On Thu, September 9, 2010 1:10 pm, Matthew Kaufman wrote:
On 9/9/2010 8:37 AM, Ralph Smith wrote:
We have a requirement for approximately ten radio sites to be
synchronized
to within 30 ns of each other.
30 ns seems a little closer than most radio site applications
Ralph Smith wrote:
O
We are not syncing time slots for communications. The timing requirement
is for determining aircraft position by multilateration. Timing errors
translate into position uncertainty.
What's your carrier freq? In mountainous regions you'll probably have
better luck at the
Ralph Smith wrote:
On Sep 9, 2010, at 8:01 PM, Rick Karlquist wrote:
I would like to point out that the environmental sensitivities of
the 5071A are unmeasureable, and the measurement threshold is
far below 5.8E-14. I would estimate that the 5071A (and ONLY the 5071A
among commercial clocks)
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