cellphone coverage for data

Discussion in 'NZ Computing' started by gamma, Jan 24, 2010.

  1. gamma

    gamma Guest

    Hi

    I'm trying to find a way to reliably send small amounts of data/text
    over a cellular network to a guy with a smart phone wandering round a
    building for validation of a fire alarm system. I've heard that data
    and text messages can reach places where voice/conversation doesn't
    work. I'd like to get an idea of how often/ how much the cellular
    data communication to the guy with the cellphone might fail. e.g. do
    cellphones work in underground carparks or what about a multi-storey
    building surrounded by other multi-storey buildings or places where
    the line of sight to the cell site is blocked by thick concrete etc.
    If the signal doesn't work in part of a building, how likely is it
    that the guy would have to move only a short distance to get the
    signal back.

    TIA
    gamma, Jan 24, 2010
    #1
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  2. gamma

    Richard Guest

    gamma wrote:
    > Hi
    >
    > I'm trying to find a way to reliably send small amounts of data/text
    > over a cellular network to a guy with a smart phone wandering round a
    > building for validation of a fire alarm system. I've heard that data
    > and text messages can reach places where voice/conversation doesn't
    > work. I'd like to get an idea of how often/ how much the cellular
    > data communication to the guy with the cellphone might fail. e.g. do
    > cellphones work in underground carparks or what about a multi-storey
    > building surrounded by other multi-storey buildings or places where
    > the line of sight to the cell site is blocked by thick concrete etc.
    > If the signal doesn't work in part of a building, how likely is it
    > that the guy would have to move only a short distance to get the
    > signal back.


    If there is poor coverage in the building that is something else that
    the building management should address.

    Coverage on all networks in buildings seems to suck. Ones where they
    have installed gear in will work well. Others you will usually lose
    coverage within a few meters of windows etc as there is not a great deal
    of signal sitting around outside to start with.
    Richard, Jan 24, 2010
    #2
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  3. In message <02541d09-b63a-453d-
    >, gamma wrote:

    > I'm trying to find a way to reliably send small amounts of data/text
    > over a cellular network to a guy with a smart phone wandering round a
    > building for validation of a fire alarm system.


    I was thinking you could modulate the AC powerline carrier and pick up the
    signal off the incandescent lights.

    Probably wouldn’t work with fluorescents, though ...
    Lawrence D'Oliveiro, Jan 24, 2010
    #3
  4. gamma

    PeeCee Guest

    "gamma" <> wrote in message
    news:...
    > Hi
    >
    > I'm trying to find a way to reliably send small amounts of data/text
    > over a cellular network to a guy with a smart phone wandering round a
    > building for validation of a fire alarm system. I've heard that data
    > and text messages can reach places where voice/conversation doesn't
    > work. I'd like to get an idea of how often/ how much the cellular
    > data communication to the guy with the cellphone might fail. e.g. do
    > cellphones work in underground carparks or what about a multi-storey
    > building surrounded by other multi-storey buildings or places where
    > the line of sight to the cell site is blocked by thick concrete etc.
    > If the signal doesn't work in part of a building, how likely is it
    > that the guy would have to move only a short distance to get the
    > signal back.
    >
    > TIA



    Hi

    No data has no more penetration power than voice.
    The reason you 'may' think texting is more reliable is the txt will sit
    waiting on the servers until the Cell Phone appears on the network long
    enough for the txt to be transferred.
    As it only takes a few seconds to transfer, the txt it may get through when
    the Cell Phone is in a marginal location that you would normally dismiss as
    being unuseable.

    You have to think in terms of radio signals to understand why certain
    locations have difficulty staying in contact.
    Deep inside a multi story building or a Car park is like being inside a
    huge steel faraday cage.
    The steel and other materials simply screen the signal out.
    If you want more 'reliability' then you will have to ensure the Cell Phone
    can 'see' the Cell Tower for longer.

    To do this you could look to the following:

    1 Move to a location the signal reaches.
    Not what you want.
    2 Boost the power of both the Cell Phone and Cell Tower transmitters (ie
    flood the cage with so much RF that 'some' leaks in and out)
    Roll out the tin foil for the greenies, and the cheque book for the extra
    equipment.
    3 Install Cell repeaters throughout the building.
    Who is going to pay for this?

    Alternatively you could look at utilising the wiring already built into the
    Alarm system and piggy back your test (?) signals back to base over the same
    wiring.
    (no not the Cell signal, but some sort of data signal to a modem at the
    buildings Demarkation point, that connects to your base)
    Of course this depends on exactly what you are trying to do with the data
    over the Cell network system you describe.
    A bit more detail would help in that regard.

    Best
    Paul.
    PeeCee, Jan 26, 2010
    #4
  5. gamma

    PeeCee Guest

    Re: cellphone coverage for data: addendum

    "PeeCee" <> wrote in message
    news:hjldg8$lio$...
    >
    > "gamma" <> wrote in message
    > news:...
    >> Hi
    >>
    >> I'm trying to find a way to reliably send small amounts of data/text
    >> over a cellular network to a guy with a smart phone wandering round a
    >> building for validation of a fire alarm system. I've heard that data
    >> and text messages can reach places where voice/conversation doesn't
    >> work. I'd like to get an idea of how often/ how much the cellular
    >> data communication to the guy with the cellphone might fail. e.g. do
    >> cellphones work in underground carparks or what about a multi-storey
    >> building surrounded by other multi-storey buildings or places where
    >> the line of sight to the cell site is blocked by thick concrete etc.
    >> If the signal doesn't work in part of a building, how likely is it
    >> that the guy would have to move only a short distance to get the
    >> signal back.
    >>
    >> TIA

    >
    >
    > Hi
    >
    > No data has no more penetration power than voice.
    > The reason you 'may' think texting is more reliable is the txt will sit
    > waiting on the servers until the Cell Phone appears on the network long
    > enough for the txt to be transferred.
    > As it only takes a few seconds to transfer, the txt it may get through
    > when the Cell Phone is in a marginal location that you would normally
    > dismiss as being unuseable.
    >
    > You have to think in terms of radio signals to understand why certain
    > locations have difficulty staying in contact.
    > Deep inside a multi story building or a Car park is like being inside a
    > huge steel faraday cage.
    > The steel and other materials simply screen the signal out.
    > If you want more 'reliability' then you will have to ensure the Cell Phone
    > can 'see' the Cell Tower for longer.
    >
    > To do this you could look to the following:
    >
    > 1 Move to a location the signal reaches.
    > Not what you want.
    > 2 Boost the power of both the Cell Phone and Cell Tower transmitters (ie
    > flood the cage with so much RF that 'some' leaks in and out)
    > Roll out the tin foil for the greenies, and the cheque book for the extra
    > equipment.
    > 3 Install Cell repeaters throughout the building.
    > Who is going to pay for this?
    >
    > Alternatively you could look at utilising the wiring already built into
    > the Alarm system and piggy back your test (?) signals back to base over
    > the same wiring.
    > (no not the Cell signal, but some sort of data signal to a modem at the
    > buildings Demarkation point, that connects to your base)
    > Of course this depends on exactly what you are trying to do with the data
    > over the Cell network system you describe.
    > A bit more detail would help in that regard.
    >
    > Best
    > Paul.



    BTW
    Forgot to add that texting is not a time guaranteed service.
    A text sent now 'may' not in fact turn up on the destination phone for hours
    after being sent.
    Kinda frustrating if one txt gets hung in the system and you keep asking
    where it is.
    Do you phone the guy, send another txt......

    FWIW
    Paul.
    PeeCee, Jan 26, 2010
    #5
  6. gamma

    peterwn Guest

    On Jan 26, 1:37 pm, "PeeCee" <> wrote:

    >
    > Alternatively you could look at utilising the wiring already built into the
    > Alarm system and piggy back your test (?) signals back to base over the same
    > wiring.


    It may be that fire alarm standards do not permit extraneous uses of
    fire alarm wiring. Anyway the sensors are daisy chained like Christmas
    tree lights so there is no regular 'go' and 'return' path.

    The building electrical reticulation could be used but difficulties
    would include three phase supply (you would need to inject and extract
    on the same phase), the relatively low impedance of the building
    substation transformer sinking the signal, multiple transformers
    feeding separate LT networks, fluorescent light capacitors sinking
    signal and longer runs compared with domestic wiring. Also omputers,
    printers etc push all sorts of crap into the mains but are not too
    tolerant of receiving such crap.
    peterwn, Jan 26, 2010
    #6
  7. gamma

    gamma Guest

    On Jan 26, 2:28 pm, peterwn <> wrote:
    > On Jan 26, 1:37 pm, "PeeCee" <> wrote:
    >
    >
    >
    > > Alternatively you could look at utilising the wiring already built into the
    > > Alarm system and piggy back your test (?) signals back to base over the same
    > > wiring.

    >
    > It may be that fire alarm standards do not permit extraneous uses of
    > fire alarm wiring. Anyway the sensors are daisy chained like Christmas
    > tree lights so there is no regular 'go' and 'return' path.
    >
    > The building electrical reticulation could be used but difficulties
    > would include three phase supply (you would need to inject and extract
    > on the same phase), the relatively low impedance of the building
    > substation transformer sinking the signal, multiple transformers
    > feeding separate LT networks, fluorescent light capacitors sinking
    > signal and longer runs compared with domestic wiring.  Also omputers,
    > printers etc push all sorts of crap into the mains but are not too
    > tolerant of receiving such crap.


    Sorry for the late reply, I've been away. Thanks for all the ideas.
    The information being sent by the fire panel is roughly, say, 100
    characters of text, once every 2 - 3 minutes maybe - identifying
    which detector/sensor has been activated. The fire alarm wiring can't
    be used because it's a distributed addressable system with a number of
    micros scattered around the building and none of the sensor wiring
    goes back to the main fire panel. I wonder how well mobile cell
    repeaters would work and how much they cost.
    gamma, Feb 19, 2010
    #7
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