Shaw@udel.edu (01/17/91)
Philisophically, scientifically, or just for a laugh ... How is time effected by war? Hard times in the gulf. Our thoughts and worries are with them. Mark Shaw U of D
ccplumb@rose.uwaterloo.ca (Colin Plumb) (01/17/91)
Shaw@udel.edu wrote: >Philisophically, scientifically, or just for a laugh ... >How is time effected by war? Historically, wars have been major events that other events can be neasured relative to, so I suppose in that sense war creates time. But really, while war may effect change in ownership of some things, I don't think it affects time very much, let alone effects it. (Well, there's the emergency time-dilation effect, but I don't think it affects non-biological clocks.) -- -Colin
Mills@udel.edu (01/18/91)
Colin, We will know the status of timekeeping in the Gulf more precisely when we learn the fate of the LORAN-C station in Kuwait operated by the previous government. Dave
milton@lion.ecn.purdue.edu (Milton D Miller) (01/18/91)
In article <9101170200.aa15102@louie.udel.edu> Shaw@udel.edu (Mark Shaw) writes: >Philisophically, scientifically, or just for a laugh ... >How is time effected by war? > In article <9101171132.aa10312@huey.udel.edu> Mills@udel.edu writes: >Colin, > >We will know the status of timekeeping in the Gulf more precisely >when we learn the fate of the LORAN-C station in Kuwait operated >by the previous government. > >Dave I found this article posted by Patty Winter for Phil Karn; it is not quite your question, but sort of the reverse: not how does war affect time, but how does time affect war. milton >From: winter@apple.com (Patty Winter) >Newsgroups: rec.ham-radio >Subject: Attack planning by celestial navigation? (P. Karn) >Message-ID: <48202@apple.Apple.COM> >Date: 17 Jan 91 07:38:19 GMT >Sender: winter@Apple.COM >Reply-To: karn@thumper.bellcore.com In article <48202@apple.Apple.COM> karn@thumper.bellcore.com writes: > > >[Phil's news server is acting up tonight so he asked me to post this >for him. His copy will probably show up on the net eventually. --pw] > > >Tuesday afternoon I read in Aviation Week that only 10 of the DoD's planned >18 Global Positioning System (GPS) block II satellites have been launched >and were operational. This means that the GPS navigation service is not yet >continuous world wide. > >It suddenly occurred to me that GPS coverage windows might be a factor in >the timing of the US attack on Iraq and Kuwait; especially at the beginning >of an nighttime air attack, precise and accurate navigation would be very >important. > >Since I have both the GPS operational status listing and a complete set of >GPS satellite orbital elements, I thought it might be interesting to run off >a set of GPS coverage windows for Baghdad. Unfortunately I didn't have time >to write the program until well after the attack had begun tonight, but I >think the results are still very interesting. > >A GPS receiver requires at least 4 satellites to be visible simultaneously >in order to produce an unambigous fix in latitude, longitude, altitude and >time. (Theoretically, you need only three satellites if you have an >accurate, i.e., atomic, clock in the receiver. But lots of civilian GPS >receivers have been shipped to Saudi Arabia, and these certainly don't have >atomic clocks.) > >Here are the results. > >Sunset in Baghdad occurred at about 1500 UTC on Wednesday the 16th (6pm >local time). At that time, there was four satellite coverage. This lasted >about two hours, when there was a 10 minute period in which only three >satellites were visible, and then four satellite coverage returned for >another hour. > >However, at that point, coverage got much poorer (at one point consisting of >only one satellite) until 2240 UTC when three satellites returned. Four >satellites returned at 0040 UTC. At least four satellites were then visible >until 0320 UTC. Four satellite coverage returned at 0600 UTC. > >The actual attack on Baghdad started at 0000 UTC on the 17th. It seems to >have lasted for several hours. And now a report on CNN right now (0612 UTC) >says that a second wave might be starting. > >Hmmm. Could it be...? > >The region does have good continuous Loran-C coverage from permanent sites >in Saudi Arabia, and of course inertial navigation is probably available in >every US military plane and missiles. On the other hand, GPS is the most >accurate navigation system ever built. Its availability might have been a >factor in planning, especially given the billions of dollars that the DoD >has invested in it so far... > >Phil
ado@elsie.nci.nih.gov (Arthur David Olson) (01/18/91)
> We will know the status of timekeeping in the Gulf more precisely > when we learn the fate of the LORAN-C station in Kuwait operated > by the previous government. Apologies for wandering off subject. . .but does anyone know if the Saudi Arabia still use solar time, either by law or practice? If so, when do they adjust their clocks? -- Arthur David Olson ado@elsie.nci.nih.gov ADO and Elsie are Ampex and Borden trademarks
Shaw@udel.edu (01/18/91)
Considering that the previous message stated the existance of Loran-C in Saudi Arabia, then if solar time is used it is only traditional. Or perhaps they accept the outside as required but shun it otherwise as is the case with so many other things. Dr. Mills is our authority on the Middleast though so perhaps he knows. Mark
budden@MANTA.NOSC.MIL (Rex A. Buddenberg) (01/18/91)
------- I have no specific facts on the two Saudi chains, but all Loran systems are timed more or less the same. There are about three issues herein: - all Loran systems that I know anything about use UTC as the time reference. So, while I don't have words in writing that say that, I'm sure it's a safe bet that those chains use UTC. - within the chain, the Saudi systems are 'Time of Transmission' systems. This means that each station is independently clocked to UTC and the system does not respond to conductivity changes. By contrast, the Coast Guard systems are all 'time delay' or 'system area monitor' systems where we latch the master to UTC but adjust the secondaries back and forth in time to provide stable time delay characteristics 'in the center of the coverage area' which translates to 'where we locate the monitor'. - in reality, the two systems don't have a whole lot of difference from the time receiver point of view -- we can estimate it as less than a usec in almost all real instances with real loran systems. And much less in all-salt- water paths. b -------
Mills@udel.edu (01/19/91)
Mark, A LORAN-C receiver is not a common household item in a Bedouin tent. I am no authority on national peculiarities of local timetelling other than to observe that in those places I have visited the clocks on the wall do not violate the Principle of Least Astonishment. Usually, in faraway places, the most important client for good time is the maritime navigation community. Most serious seafaring nations and high-seas naval services broadcast timing pips at least once per day from coastal communications stations. The frequencies and times of these broadcasts are shown in ITU publications and, in some cases, in the World Radio and TV Handbook published yearly. While I have not been able to confirm this, I have observed the five pips broadcast throughout the BBC services just before the hour are right on-tick relative to UTC. If I can figure out a way to extract their timing precisely, I may be able to figure out the relay routes. I have done that for some VOA circuits. Officially, time coordination throughout the international participants is done by the Bureau of Weights and Measures in Paris. There should be some sort of explanatory document available from them. As far as the Bedouin and Hindu are concerned, from what I fathom, these countries are at low latitudes relative to those we are most familiar with. At such latitueds the sun rises and sets pretty much the same time 6h-18h local time throughout the year and the sunlight comes on and goes off quickly. The only real need for more accurate time than that is to know when to turn the shortwave radio on. Dave