[time-nuts] Bit of time related humor for those of you in need of a distraction
Found an old birthday card with these sentiments ... It's your birthday but hey ... don't worry about getting older. After all, what is age anyway? I mean, when you consider that man's concept of time is actually pretty meaningless in the context of the space-time continuum, it really doesn't matter whether you're nineteen or ninety. Inside it says "God. I love playing with old people's heads." Forgive me, tvb. Bill Hawkins, who is confined to a life care community that has so far had no COVID-19 cases by isolating us from the community. The isolation increases stress, and humor is palliative. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] New Subscriber, DIY GPSDO project (yes, another one)
Try https://en.wikipedia.org/wiki/PID_controller If that doesn't help, what we used to do for industrial process controllers was to set Reset time to the largest value and Derivative to zero (to disable them) and then increasethe gain until the loop oscillated when you made a step change to the setpoint, then you used 70% of that value for gain. The period of oscillation told you how to do Reset, but I don't remember that. Conservative settings were used because control valves were not linear. Heaters are generally linear. Bill Hawkins, whose memory isn't what it used to be. On Sat, Mar 7, 2020, at 5:04 PM, Hal Murray wrote: > > kb...@n1k.org said: > > As far as I know there is no “closed form” solution to tuning a GPSDO. It is > > very much a measure / tweak / measure / tweak sort of thing. > > I've seen a recipe for tuning a PID controller. That was ages ago. I wonder > where. > > The key idea was that you needed to be able to poke the system and see how it > responded. > > Google for >tune PID< gets several hits that might be worth investigating. > > > -- > These are my opinions. I hate spam. > > > > > > ___ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. > ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] A Research Proposal
Um, you're quite right that DC lines have no phase angle - unless you call a polarity reversal a 180 degree shift. I was referring to the phase angle of the AC side of an inverter with respect to the average phase angle of the grid that it is connected to. It behaves just like a synchronous machine. Advance the phase angle of the inverter and it pumps energy into the grid. The inverter at the other end of the DC line must be lagging in order to take power from that grid. Conservation of energy says you must take more power than you deliver in order to cover the resistive and corona losses in the DC line and the conversion losses in the inverters. Perhaps the source inverter phase angle is controlled by the DC output voltage, and the load phase angle is controlled by the DC current. Controlling the load inverter phase angle would be like adjusting the steam to a turbine coupled to a generator. I have no knowledge of how control is actually accomplished. Bill Hawkins On Mon, Jul 8, 2019, at 6:12 AM, Hal Murray wrote: > > bill.i...@pobox.com said: > > Since the direction of power flow depends on the phase angle between the > > synchronous source and load, it seems to me that the difference between the > > average phase angle in one region and that in another (at the ends of a DC > > transmission line) will tell you which way power is flowing. > > Nope. The phase angle difference tells you a lot on an AC line, but nothing > on a DC line. For DC, the frequencies can even be different. That means the > phase angle is changing, and it can wrap around while the phase angle on an > AC > system is always small. > > A classic 3 phase synchronous motor is also a generator if you are pushing it > rather than it is pushing you. The sign of the phase angle flips between > motor and generator. In this context, the phase angle is the angle the > magnetic lines make between the rotor and stator. > > > -- > These are my opinions. I hate spam. > > > > > ___ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. > ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] A Research Proposal
Since the direction of power flow depends on the phase angle between the synchronous source and load, it seems to me that the difference between the average phase angle in one region and that in another (at the ends of a DC transmission line) will tell you which way power is flowing. I didn't claim that the amount of power could be determined. It can't. Disclaimer - I'm a mechanical engineer who has made a career in the control of physical machines. I've been interested in the power line stuff since a visit to the PenJerDel region distribution control center in the seventies. Now that I'm 81, there's probably some holes in that knowledge. Bill Hawkins P.S. I don't know who Bob is. That's the address pobox gave me when I said "Reply to List" On Sun, Jul 7, 2019, at 5:00 PM, Hal Murray wrote: > > > So no, you can't compare data from different regions, unless you want to > > know > > which way DC power is flowing. > > How does knowing data about two regions tell me anything about how much power > is flowing and which direction? > > > > -- > These are my opinions. I hate spam. > > > > > ___ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. > ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] A Research Proposal
Group, We've discussed this before, but maybe it needs to be said again. Line frequency is not constant. There is no master PLL. Approximate frequency is maintained by a central power dispatching office in each of the four (?) regions tied together by their power distribution grid. The dispatcher's goal is to create the same number of cycles of AC each day. IIRC, power is bought and sold by the number of cycles generated. As the daytime load increases, the generators slow down a bit. Note that it is not possible for each generating station to control its frequency, as that would not be stable. Instead, the dispatcher asks various plant operators to generate more or less steam (or water flow) in order to increase the frequency. When the load drops at night, the generators speed up a bit, and steam has to be reduced. At the end of the day, so to speak, the number of cycles generated is very nearly equal to the number generated if the line frequency had been steady at 60 (or 50) cycles per second. Synchronous clocks stay accurate although they may be off by a few seconds as dispatchers scramble to get enough steam to keep up. So yes, you can get phase data within a region but you must compensate timing data as the frequency varies. The regions are connected to each other for purposes of power sharing with DC transmission lines. These use inverters to convert between AC and DC. The AC frequency is controlled by the grid that it is tied to. Phase angle can be changed to change the amount and direction of the power transferred. So no, you can't compare data from different regions, unless you want to know which way DC power is flowing. I hope this was informative. Bill Hawkins On Thu, Jul 4, 2019, at 2:00 PM, Andy Backus wrote: > Historically, and even today, the steady frequency of AC power has been > used for timekeeping. So there may be interest here in the following > research proposal: > > Within a given power distribution grid, several observers as widely > separated geographically as possible, time stamp the first two zero > crossings of the power line after each UTC second – over the course of > 24 hours (86,400 pairs of data). > > Popularly conceived, all the components of a power distribution grid > are phase locked – though, of course, power is taken in and out by > varying degrees of lead or lag. Frequency is maintained by a constant > balancing act between load and generation. > > Typical power distribution grids, however, are sized on a scale of > thousands of miles. “Locking phase,” then, is problematic simply on > the basis of the limits of information transmission rate. Even at c, > every 1000 miles takes 5 ms, which represents a third to a quarter of > the period of the AC power waveform. > > Many interesting phenomena might result from that reality, which > suggests a certain constrained flexibility over large distances – > almost as if the system is like a large lake of viscous liquid. When > there are local disturbances such as rapid load changes or sudden > generation adjustments, for example, it is quite possible harmonic > ripples could be propagated through the system. > > Such effects could be observed by comparing phase data across > significant distances within a distribution grid. > > Andy Backus > Bellingham, WA > USA > > > From: time-nuts on behalf of Thomas > D. Erb > Sent: Thursday, July 4, 2019 5:23 AM > To: time-nuts@lists.febo.com > Subject: Re: [time-nuts] 60 Hz frequency and phase measurement > snip > I had a recent tour of a power station - the operators had no idea the > output was synchronized to a time standard - they just synchronize with > the local grid. > > Thomas D. Erb > p:508-359-4396 > f:508-359-4482 > a:97 West Street, Medfield, MA 02052 USA > e: t...@electrictime.com > w:www.electrictime.com<http://www.electrictime.com> > Tower & Street Clocks Since 1928 > ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] Noisy clocks [Was: Atomic Clocks]
Well, your first clue should be the heavy box that contains the hardware. Don't recall any other HP gear built that way. The box could have been an aluminum casting. I had two of them with about the same noise, many years ago (but not new). I used standard fiberglass wall insulation to line a wooden cabinet that also contained the 103 crystal standard. That made the noise bearable and kept the 103 temperature stable. Of course, you had to open the front insulated door to see the clock. Never found out if it was the 1 KC stepper motor or the gearbox making the noise. Should have tried heavy grease on the motor gears, but that would make a mess of the chassis. Too late now. Bill Hawkins On Fri, Jan 4, 2019, at 4:01 PM, Jeremy Nichols wrote: > Does anyone know how loud the mechanical analog clock in the HP-113AR > Frequency Divider/Clock is supposed to be? Mine is loud to the point of > being annoying. I've surrounded it with insulation, which helps, but it's > not really quiet. I never saw one of these things when new (1960) so I've > no idea whether the noise is simply a function of design and construction > or if mine is worn after 50+ years of use. [The noise is mechanical > gear-type noise, not 1000 Hz whine from the driving frequency.] > > Jeremy > > On Fri, Jan 4, 2019 at 2:11 PM paul swed wrote: > > > > > On Fri, Jan 4, 2019 at 4:28 PM Mark Sims wrote: > > > > > My 5065A has the Patek clock. Those suckers are LOUD. You can hear > > them > > > ticking two counties away... hence mine is always disabled. Once > > started, > > > you have to power cycle the machine to get it to shut up. > > > ___ > > > > > > ___ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] Free Stuff - Moving Forward
Quickly, there was a man named Larry Ware who ran a Home for Wayward Test Equipment. He established what came to be called "The Rules of Ware" for selling things. Rather than first reply, he offered stuff to people with the best story for how they would use it. Doesn't eliminate quick resale but reduces the probability. Bill Hawkins ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] Loss of NIST transmitters at Colorado and Hawaii
Group, This subject needs some additional detail. I found an article with comments at https://swling.com/blog/2018/08/nist-fy2019-budget-includes-request-to-shutdown-wwv-and-wwvh/ It is not clear whether WWVB will still be available for all of our cheap "atomic" clocks. One comment says that White House budgets are usually ignored in congress. Another says that it is NIST that cut WWV and WWVH, not the White House. Can anyone clarify the situation? Bill Hawkins Sent from my retirement home in MN Change causes confusion until new methods are learned, and a deep sense of loss when something familiar goes away. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] GPS Antenna Grounding/Lightning protection.
Seems to me that lightning protection for timenuts who put things on masts keeps this from being completely off topic. People who store explosives in earthen bunkers have learned from many years of experience how far away bunkers have to be spaced so than an explosion in one bunker won't affect others. That same body of experience came up with the cone of protection. It is not a myth. Note that lightningsafety.com sells lightning protection. The scrolling set of pictures on the home page shows a picture of four masts protecting a rocket launch site. Bill Hawkins P.S. Lightning can enter a home in other ways. A neighbor had a direct hit to a tree 15 feet from the house. After generating enough steam in a 2 foot diameter tree to split the length of it, a side strike hit an outdoor light and did considerable damage in the house. The tree was not the highest thing around. That same strike produced an EMP that took out one of my two GPS antennas, about 100 feet away. The time from flash to BANG was about 100 milliseconds. No, I didn't measure it - I experienced it. -Original Message- From: time-nuts [mailto:time-nuts-boun...@lists.febo.com] On Behalf Of Van Horn, David Sent: Tuesday, June 19, 2018 11:22 AM About that "cone of protection" http://lightningsafety.com/nlsi_pls/cone-of-protection-myth.html ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to https://lists.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] GPS Antenna Grounding/Lightning protection.
Oz has some useful observations. I've worked on a 50 foot ocean-going fishing party boat that had a 10 foot aluminum mast on top of the wheel house. That will be the shortest path to ground on the open sea. The best you can do is to connect a 4" wide copper strap from the mast to the keel, with as few bends as possible and none greater than 45 degrees. This seems to work. I've also worked at a blasting cap plant where 50 foot masts were erected at both ends of an earth-covered powder magazine. They provide a "cone of protection" that prevents a direct hit on the magazine. The mast grounds were measured quarterly with a hand-cranked device specifically made for ground resistance. It had to be less than 100 milliohms. But if you really want protection from a direct hit, you must disconnect the tower device(s) before the storm hits. The coaxial cable must have only one ground point. The other end should be far from a metallic ground. You'll probably lose any electronics in the antenna, but there are far more expensive things in your lab. You will also have to deal with the electromagnetic pulse, so all of your equipment, including the computers, must have a common ground point. This provides a ground plane that can change potential relative to the Earth without inducing potentials between devices. Every connection to/from the ground plane must have a surge arrestor. If the risk of nearby direct hits is high enough, isolate the ground plane from all external connections before the storm. You'll need battery backup on the ground plane for all temperature controlled ovens and crystal oscillators. Maybe the Cs and Rb packages also need to keep running. It would help to move away from Florida, or high hilltops. Bill Hawkins -Original Message- From: time-nuts [mailto:time-nuts-boun...@lists.febo.com] On Behalf Of Oz-in-DFW Sent: Monday, June 18, 2018 2:25 PM To: time-nuts@lists.febo.com Subject: Re: [time-nuts] GPS Antenna Grounding/Lightning protection. Not sure I have much to specific offer, other than some observations. 1. A path to ground is only a small part of the story. What's really important is the ground reference of all equipment to all other equipment. The huge currents and substantial risetimes can cause large voltage spikes across even large conductors (>8 AWG.) You want everything to stay at the same voltage reference, and you'd really like to keep that close enough to ground to prevent arcs from that equipment to ground and other equipment. 2. Long wire runs of even large gauge wire are inductors and can be of little value during an event. 3. No matter what you do, it's unlikely you can do anything within economical reason to survive a direct strike and the 10's to 100's of kiloamps involved. The real question is how close of a near miss can you survive. 4. Most of the non-telecom smoking fails I've seen have been power line transients. If you took a direct tower hit it's more likely than not that your RG-6 would now be plating on a tower leg. An old tower can be a pretty poor ground for the microseconds (or sometimes milliseconds when you consider return strokes) it takes the corrosion in the leg joints to flashover and fuse, or resistance heat and weld. 5. The large currents of a direct strike have predictable but less than obvious physical effects like conductor shortening (if they don't fuse,) and other significant forces caused by magnetic attraction of conductors. One failure case I saw years ago collapsed the conduit around a ground conductor. Made no sense until we discovered that the conduit was the actual ground path. I'll see if I can find the pictures. 6. Even near misses can induce huge currents (kiloamps) on their own, particularly in long vertical cable runs. I've seen solder joints in small empty copper water pipes melt and reflow from a strike a 100 feet away. 7. The best coax lightning suppression units I have seen are essentially 1/4 wave grounded stubs. These are common is cell site installations (and the top /AND/ bottom of the lines.) These are always at DC ground and the coax is a the weak point (and ultimately the fuse.) I've seen them surplus and at hamfests and some cover GPS freqs. 8. A near strike will induce some really impressive voltages on Ethernet cable runs. Most residential buildings are electromagnetically transparent and the protection on most Ethernet interfaces is oriented toward ESD. Oz (in DFW) On 6/18/2018 1:29 PM, Dan Kemppainen wrote: > Hi, > > I have (or had, I guess) a GPS antenna on a tower that took a > lightning hit yesterday. > > You can tell it's going to be a bad day when you walk into your shop, > and smell burnt electronics. Still have to troubleshoot exactly what
