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911 Power Boost
Temporary power boost reaches an out-of-range cell tower in emergencies | |
Your car runs off the interstate
during a blizzard. You're in a ditch,
stuck in the front seat with multiple
injuries, and snow is pouring in
through the smashed windscreen.
You can reach your cellphone. You
dial 911, but you're out of service
range. Do you really care about
having
two more days of standby
power on your mobile, when you're
likely to die of internal haemorraging
or exposure within a few hours?
You hit the "Emergency Power Boost"
button. It increments the transmit
power of your handset upwards in
stages until it finds a tower it can
link to. An onscreen graphic
provides an indication of estimated
call time. You also have the option
of sending a pre-composed SMS
with a single button if you are
unable to speak, or if talk time is
likely to be short.
Signal boosters are Widely Baked
http://www.dazer.com/booster.jsp
...but nothing's gonna help you if you're really out of service range. [DrCurry, Jul 17 2005]
Annotation:
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Good idea, but would it work? I'm sure
you could have a phone with a "high
power send" option, but what about
receiving? I think (not sure) that
communication has to be two-way even
to 'send', since the phone has to
negotiate with the tower. So, you'd
need a more sensitive ariel on the
phone. Or is this not the limitation? |
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I'm disappointed - I was hoping this was going to be a way of getting a few extra horsepower out of my turbocharged flat-six. |
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Absolutely this would work. It's not even close to hard. Marine radios have two settings:
1 Watt / 25 Watts. You try 1, and if it doesn't go through you use 25. |
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//Absolutely this would work.// Not if
using your cell-phone depends on
receiving signals from the tower it
won't. I think. |
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You may be able to send but it's doubtful you would receive, unless the network signal is also boosted. |
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Exactly - but even 'sending' requires
negotiation between the phone and the
base-station, as I understand it. |
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Haven't Porches enough power as it is? |
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You can never have too much power. |
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//You may be able to send but it's doubtful you would receive, unless the network signal is also boosted// But wouldn't the phone send a message as part of the negotiation saying that power had been boosted, so that the base-station could reply in a similar fashion? |
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Before the phone can do anything under the GSM standard it has to authenticate to the network. Even allowing that this may not be the case for emergency calls (I'm not sure on that point) 2-way negotiation is still required in order to set the timing advance of the phone's transmissions. The maximum diameter of a GSM cell as governed by this limiting factor is approximately 35km. Nice idea but [-] impractical. |
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How about an emergency helium bottle and weather balloon contained in the phone? Then, suspended from the balloon, the phone could rise and its signal easily cover a much wider area. How it would be traced back to the ditch-ridden would-be rescuee...I haven't worked out yet. |
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Uae a 1.5MW bluetooth headset... and fry your ear if you get hungry. |
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Based on the comparative size of the two transmitters, it seems reasonable to assume that the cellphone is usually the limiting factor for range, does it not? |
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Nope [Madcat], unfortunately not. The main limiting factor is as I described above the timing advance.
Because a phone is allocated a timeslot to use, if it is a long way away from the base station then in order for its signals to arrive in said slot it must set a timing advance so that it transmits earlier as compensation for the time its signals spend in transit. This advance figure can only get so big before the phone arrives at a situation where it needs to transmit its signal and receive one from the BTS simultaneously. There are other more complicated reasons why it won't work but my head hurts thinking about them.
The practical limit on GSM cell size is 35km across if you're prepared to tolerate shoddy call quality. You could get bigger cells if you lost some channels, perhaps a scheme worth considering for sparsely populated areas. This idea, however, will *not* work. |
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Just put all the ditches near cellphone
towers. |
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I can only assume CDMA works on a different timing setup, [DB]? |
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[basepair], no, that's impractical. I suggest that the cellphone towers be put near the ditches. Planning permission for ditches must include foundations for a cellphone tower. |
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CDMA is an entirely distinct kettle of aquatic life [UB]. I'm only just getting to grips with 3G/UMTS so I'll let someone with more knowledge field that one! |
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CDMA stands for Code Division
Multiple Access. GSM stands for
Global System for Mobiles or
something, but my understanding
is it works on TDMA (Time
Division) - hence [DocBrown]'s
anno. |
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Here in Australia, CDMA was
commissioned as a replacement
for the scrapped analogue network
in rural areas, with some promises
of better range than GSM (which is
mostly urban). |
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So -maybe- this would work with
CDMA phones. |
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