Re: [time-nuts] Thunderbolt power supply hookup

Thanks that all makes sense and power up went ok. - Original Message From: Hal Murray To: Discussion of precise time and frequency measurement Sent: Fri, September 10, 2010 11:04:21 PM Subject: Re: [time-nuts] Thunderbolt power supply hookup mspencer12...@yahoo.ca said: > Would any

Re: [time-nuts] Thunderbolt power supply hookup

Thanks that is very helpfull. - Original Message From: Roberto Barrios To: time-nuts@febo.com Sent: Fri, September 10, 2010 10:50:51 PM Subject: [time-nuts] RE: Thunderbolt power supply hookup Hi Mark, You will find that and lots of other very interesting info at tvb's excellent web

Re: [time-nuts] Thunderbolt power supply hookup

mspencer12...@yahoo.ca said: > Would any one be able to point me towards a web site that shows the power > supply pinout for the bare thunderbolt board (without the power supply > board.) http://www.leapsecond.com/pages/tbolt/power.htm -- These are my opinions, not necessarily my employer's.

[time-nuts] RE: Thunderbolt power supply hookup

Hi Mark, You will find that and lots of other very interesting info at tvb's excellent website: http://www.leapsecond.com/pages/tbolt/power.htm The pictures do not show the bare PCB but you can guess how it is placed inside the housing from the pictures. Regards, Roberto EB4EQA Message: 8

Re: [time-nuts] Timing Distribution in Mountainous Terrain

jees, Bob, it's called a TDR - Original Message - From: "Bob Camp" To: "Discussion of precise time and frequency measurement" Sent: Friday, September 10, 2010 9:27 PM Subject: Re: [time-nuts] Timing Distribution in Mountainous Terrain Hi The assumption is that you can "bounce" a p

Re: [time-nuts] Timing Distribution in Mountainous Terrain

ground wave has variation due to changes in refractive index over the path. - Original Message - From: "WB6BNQ" To: "Discussion of precise time and frequency measurement" Sent: Friday, September 10, 2010 6:46 PM Subject: Re: [time-nuts] Timing Distribution in Mountainous Terrain Ha

[time-nuts] Thunderbolt power supply hookup

Would any one be able to point me towards a web site that shows the power supply pinout for the bare thunderbolt board (without the power supply board.) >From looking at the TPAR site I believe I have the pinout sorted out but a >clear diagram would be very helpfull. All the best Mark Spence

Re: [time-nuts] Timing Distribution in Mountainous Terrain

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 d

Re: [time-nuts] Timing Distribution in Mountainous Terrain

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

Re: [time-nuts] Timing Distribution in Mountainous Terrain

Hi The assumption is that you can "bounce" a pulse off the far end of a single fiber or coax to read it's delay. Bob On Sep 10, 2010, at 10:09 PM, "J. L. Trantham" wrote: > > > -Original Message- > From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On > Behalf O

Re: [time-nuts] Timing Distribution in Mountainous Terrain

~ 1ft  = 1 ns for coax, but 1000-2000 us is common delay for long phone lines which is very frequency dependent, you would want unloaded circuits, loading coils would make for more problems. My experience with metallic circuits is limited to less than 10 miles at some point you would need an am

Re: [time-nuts] Timing Distribution in Mountainous Terrain

-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 How

Re: [time-nuts] Timing Distribution in Mountainous Terrain

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

Re: [time-nuts] Timing Distribution in Mountainous Terrain

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 c

Re: [time-nuts] Timing Distribution in Mountainous Terrain

That's why you need sufficient bean divergence on the outgoing beam Sent via BlackBerry by AT&T -Original Message- From: Stanley Reynolds Sender: time-nuts-boun...@febo.com Date: Fri, 10 Sep 2010 15:34:42 To: Discussion of precise time and frequency measurement Reply-To: Discussion of pr

Re: [time-nuts] Timing Distribution in Mountainous Terrain

How to keep hundreds of miles of copper stable or predict it's delay ? Stanley - Original Message From: "J. L. Trantham, M. D." To: Discussion of precise time and frequency measurement Sent: Fri, September 10, 2010 6:44:35 PM Subject: Re: [time-nuts] Timing Distribution in Mountainou

Re: [time-nuts] Timing Distribution in Mountainous Terrain

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 only have to transmit your position and altitude to a ground receiv

Re: [time-nuts] Timing Distribution in Mountainous Terrain

> 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

Re: [time-nuts] Timing Distribution in Mountainous Terrain

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 histo

Re: [time-nuts] Timing Distribution in Mountainous Terrain

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 transmitti

Re: [time-nuts] Timing Distribution in Mountainous Terrain

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

Re: [time-nuts] Timing Distribution in Mountainous Terrain

[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 > abo

Re: [time-nuts] Timing Distribution in Mountainous Terrain

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

Re: [time-nuts] Timing Distribution in Mountainous Terrain

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 i

Re: [time-nuts] Timing Distribution in Mountainous Terrain

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 WWV-

Re: [time-nuts] Timing Distribution in Mountainous Terrain

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, alon

Re: [time-nuts] Timing Distribution in Mountainous Terrain

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

Re: [time-nuts] Timing Distribution in Mountainous Terrain

On 9/10/2010 11:19 AM, Oz-in-DFW wrote: 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 fo

Re: [time-nuts] Timing Distribution in Mountainous Terrain

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 on

Re: [time-nuts] Timing Distribution in Mountainous Terrain

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. > >

Re: [time-nuts] Timing Distribution in Mountainous Terrain

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

Re: [time-nuts] Timing Distribution in Mountainous Terrain

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 blow

Re: [time-nuts] Timing Distribution in Mountainous Terrain

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 - Original Message From: Mark J. Blair To:

Re: [time-nuts] Timing Distribution in Mountainous Terrain

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 worl

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. 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 t

Re: [time-nuts] Timing Distribution in Mountainous Terrain

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. Th

Re: [time-nuts] Timing Distribution in Mountainous Terrain

> 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 grou

Re: [time-nuts] Timing Distribution in Mountainous Terrain

30ns for six days? You will probably will have to install Cesiums or Hydrogen Masers, a good Rubidium can drift 1.1us per day. Even with GPS it is hard to achieve, try to find a GPSDO that specifies +/-30ns to UTC some specify 30ns RMS, i.e. being < 30ns in ~70% of the time. Rob Kimberley

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 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 cou

Re: [time-nuts] Timing Distribution in Mountainous Terrain

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 go

Re: [time-nuts] Timing Distribution in Mountainous Terrain

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 >

Re: [time-nuts] Timing Distribution in Mountainous Terrain

The URL I posted earlier has an indpedth discussion of this (: It seems to imply to me that with processing a standard deviation of 8ns could be obtainable but I may have missed somethign in my quick skim thru the paper.   If I have time this weekend I'll read thru it in more detail.   It would

Re: [time-nuts] Timing Distribution in Mountainous Terrain

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. VLB

Re: [time-nuts] Timing Distribution in Mountainous Terrain

David C. Partridge wrote: Jim is it possible you just gave a workable solution: Equip each site with a small radio telescope and watch pulsars. Aren't pulsars a reliable accurate time source or do they not provide the 30nS over ten days accuracy? Pulsars *are* pretty stable.. the problem is

Re: [time-nuts] Timing Distribution in Mountainous Terrain

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 l

Re: [time-nuts] Timing Distribution in Mountainous Terrain

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

Re: [time-nuts] Timing Distribution in Mountainous Terrain

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. In aviation, 0.25 nm is 'precise'. If you get me to within 0.25 nm of the a

Re: [time-nuts] Cycling of Peltier junction

The PCR machine manufacturers just let them fail and then (when out of warranty) replace the whole themal transfer block, peltiers and heatsink at vast expense!   Robert G8RPI. --- On Fri, 10/9/10, Hal Murray wrote: From: Hal Murray Subject: Re: [time-nuts] Cycling of Peltier junction To: "D

[time-nuts] Samsung GCRU-D's available

Hi, I thought you may be interested in some Samsung GCRU-D's I have on the *Bay, closing this weekend. Let me know off-line in interested. Item number: 290470537113 Thanks for the BW, Kit VK2LL

Re: [time-nuts] OT: Christchurch NZ Quake Map

On 9 September 2010 21:20, wrote: > Brings back memories- I was on the west coast of the south island in 1990, > leaning against a large log on the beach very close to the water line at > sunset, when a quake hit. Being from California, it was fun because I was > used to experiencing quakes in

Re: [time-nuts] Timing Distribution in Mountainous Terrain

> 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 ___ time-nuts mailing list -- time-n

Re: [time-nuts] Timing Distribution in Mountainous Terrain

> 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 s

Re: [time-nuts] Timing Distribution in Mountainous Terrain

Jim is it possible you just gave a workable solution: Equip each site with a small radio telescope and watch pulsars. Aren't pulsars a reliable accurate time source or do they not provide the 30nS over ten days accuracy? Regards, David Partridge -Original Message- From: time-nuts-bo

Re: [time-nuts] Timing Distribution in Mountainous Terrain

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 measurem

Re: [time-nuts] Cycling of Peltier junction

>> Does anybody know about using the same Peltier junction for both >> heating and cooling? I'm concerned about thermal/mechanical shock >> when changing the polarity back-n-forth between hot and cold. Maybe >> there needs to be a controlled ramp, if so then how do I figure out >> the rate? > N

Re: [time-nuts] Cycling of Peltier junction (Jerome Peters)

Might be worth a glance: http://www.eevblog.com/2010/07/25/eevblog-101-hacking-your-own-peltier-lab-thermal-chamber/ ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and fo