Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!sdd.hp.com!samsung!noose.ecn.purdue.edu!lion.ecn.purdue.edu!milton From: milton@lion.ecn.purdue.edu (Milton D Miller) Newsgroups: comp.protocols.time.ntp Subject: Re: 'time' for war Keywords: Iraq, GPS Message-ID: <1991Jan17.190654.15179@noose.ecn.purdue.edu> Date: 17 Jan 91 19:06:54 GMT References: <9101170200.aa15102@louie.udel.edu> <9101171132.aa10312@huey.udel.edu> <48202@apple.Apple.COM> Sender: news@noose.ecn.purdue.edu (USENET news) Organization: Purdue University Engineering Computer Network Lines: 84 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