112 vs 999
in [UK Mobile]
|
From: Dennis Ferguson on 26 May 2010 09:43 On 2010-05-24, Theo Markettos <theom+news(a)chiark.greenend.org.uk> wrote: > Dennis Ferguson <dcferguson(a)pacbell.net> wrote: >> It is assisted GPS. The minute a standalone GPS receiver spends is >> spent acquiring satellites and downloading almanac information. With >> CDMA assisted GPS the tower (which has its own GPS receiver and is >> close to the phone) tells the phone which satellites to listen for >> and approximately when to listen (i.e. the "acquisition" information), >> the phone makes the fine timing measurements and returns the raw data, >> and the network computes the location. The phone will time signals >> from CDMA towers as well (GPS is CDMA, so timing tower signals is the >> same process) and send that back too for use when the satellites can't be >> heard. There's only a fraction of a GPS receiver in the phone, with >> the network doing the rest, and it's quick since the satellites are >> "pre-acquired". > > Thanks for that, I didn't realise the network was doing the work. Does this > also apply to assisted GPS in (eg) GSM iPhones? Does that mean positioning > doesn't work when out of signal range (or on a non-cooperative network)? No, the "assist" for a GSM phone is only the first part above; the network downloads the almanac and information about approximately where you are (i.e. tower location) and which satellites to listen for, to try to eliminate the satellite acquisition time. The phone is still required to have a full GPS receiver to compute locations, and will probably do satellite acquisition the hard way if the assist isn't available. Note that the CDMA method above is a really awful, inefficient way to support, say, a navigation application on your phone, so even CDMA phones generally have real GPS receivers when they support that. The above is a good way to support E911 location determination, though, since it requires hardly any logic in the phone (so every phone can include it) and since, in that case, you want the network to know the phone's location but not necessarily the phone itself. Dennis Ferguson
From: S Viemeister on 27 May 2010 04:14 On 5/25/2010 2:52 PM, Whiskers wrote: >> Or maybe 911, if you want to do it the American way... > > The UK chose 999 because it was easy to dial by touch on the old rotary > dial telephones and unlikely to be dialed by accident. The Americans > couldn't tolerate dialing the same number as the Brits so chose something > else when they copied the idea. > The US used x11 numbers for various services - information, time clock, long distance, etc, so 911 for emergencies made sense.
From: Graham. on 4 Jun 2010 09:13 "Chris" <me(a)privacy.net> wrote in message news:862am9F3cvU1(a)mid.dfncis.de... > Whiskers <catwheezel(a)operamail.com> wrote: >> On 2010-05-24, Chris <me(a)privacy.net> wrote: >>> Peter Whisker <pw1(a)adsl24.co.uk> wrote: >>>> Zaz <zaz(a)zaz.zaz> wrote in news:q8VIn.12977$dh7.646(a)newsfe13.ams2: >> >> [...] >> >>>> In the UK and Ireland, 999 and 112 are identical. 112 works across Europe >>>> even where they may have a different local number. >>>> >>> 999 does as well. It's the same. >>> But why don't you use 08? It's shorter :-) >> >> Three digits are less likely to be dialled accidentally than two. In the >> UK, 08 is the start of a great many numbers, so would be a very bad choice >> for emergencies! >> > Well, it is, however, working. Even in the UK:-) > (it might be disabled in UK-specific firmware, but I don't think so) > >>> Or maybe 911, if you want to do it the American way... >> >> The UK chose 999 because it was easy to dial by touch on the old rotary >> dial telephones and unlikely to be dialed by accident. The Americans >> couldn't tolerate dialing the same number as the Brits so chose something >> else when they copied the idea. >> > hehe sure. > >>> Those numbers are all doing the same - they're triggering the emergency >>> call. >> >> Yup. On modern push-button dials, 555 would be the easiest code to dial - >> there's often a tactile 'pip' on the 5 button. I believe it is used >> within some large private networks. >> > Why not. However, 999 still seems to be a good choice to me. > I think mobiles offering an emergency calls through the menu - that would > mean that you would not even have to dial any number at all... > Same if you switch on your mobile and choose "emergency call" instead of > entering the pin code. My Blackberry handles that last scenario in exactly that way Veering somewhat off topic, UK hospitals used to use the phrase "Not For 222" as a euphemism for "do not resuscitate" The expression was (maybe still is) used irrespective of the actual extension number of the crash team. -- Graham. %Profound_observation%
From: Graham. on 4 Jun 2010 14:53 > I don't know of any mobile phone handset that uses 'pulse code dialling' - > where the dial sends pulses down the wire which cause relays in the > exchange (or digital emulations of relays) to make a connection as soon as > the user dials the number. But there are still landline phones using that > system - the exchanges have to be 'backwards compatible' so that even > 60-year-old telephones can still be used. So a UK landline exchange must > not assume that the digits 08 are an emergency call - if it did, all the > millions of 0845 and 0870 etc numbers wouldn't work! I've never seen a true cellphone with a rotery dial, but the first cordless phone I ever saw about 30 years ago had a miniture dial, it worked quite well too. Someone brought it in from the Far East IIRC. > But it seems that mobile digital networks are not constrained in quite the > same way. For one thing, pulse code dialling isn't used at all, and for > another the user keys in the number required (or calls it up from the > handset memory in some way) and then hits the 'call' button to transmit > the complete number 'all at once'. Yes. It's called en-block signalling -- Graham. %Profound_observation%
From: Paulg0 on 5 Jun 2010 06:14
"Graham." <me(a)privacy.net> wrote in message news:hubi49$voa$1(a)news.eternal-september.org... > I've never seen a true cellphone with a rotery dial, > but the first cordless phone I ever saw about 30 years ago had a miniture > dial, > it worked quite well too. Someone brought it in from the Far East IIRC. http://www.rotarydialtelephones.com/rotary_dial_cell_phone.htm Paul |