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Explanation, please, of signal strength...in easy to understand English.

Discussion in 'alt.cellular.verizon' started by Harry , Jul 9, 2010.

  1. Harry 

    Harry  Guest

    I installed "RealSignal-CDMA" on my Verizon Inc, and with the network
    extender, I'm getting five bars and a signal strength of -45 while I am
    on the same floor as the device.

    The coverage in my area isn't terrific. If I go outdoors to the end of
    the driveway, I'm no longer in range of the network extender, and the
    signal strength drops to -85/-90.

    Would someone be kind enough to offer up an explanation in layman's
    terms of what these signal strength readings actually mean?

    Thanks.
     



    › See More: Explanation, please, of signal strength...in easy to understand English.
  2. Re: Explanation, please, of signal strength...in easy to understandEnglish.

    Harry  wrote:
    > I installed "RealSignal-CDMA" on my Verizon Inc, and with the network
    > extender, I'm getting five bars and a signal strength of -45 while I am
    > on the same floor as the device.
    >
    > The coverage in my area isn't terrific. If I go outdoors to the end of
    > the driveway, I'm no longer in range of the network extender, and the
    > signal strength drops to -85/-90.
    >
    > Would someone be kind enough to offer up an explanation in layman's
    > terms of what these signal strength readings actually mean?
    >
    > Thanks.


    With a consumer device such a cell phone, the readings mean little or
    nothing. Either you can make and receive calls or you can't!

    Signal strength is usually (always?) measured in microvolts/meter. The
    numbers have meaning but the meaning is not particularly useful to the
    consumer. Either you can. . . .
     
  3. Larry

    Larry Guest

    =?UTF-8?B?SGFycnkg76O/?= <naled24511@mypacks.net> wrote in
    news:89og81FqkuU1@mid.individual.net:

    > I installed "RealSignal-CDMA" on my Verizon Inc, and with the network
    > extender, I'm getting five bars and a signal strength of -45 while I

    am
    > on the same floor as the device.
    >
    > The coverage in my area isn't terrific. If I go outdoors to the end of
    > the driveway, I'm no longer in range of the network extender, and the
    > signal strength drops to -85/-90.
    >
    > Would someone be kind enough to offer up an explanation in layman's
    > terms of what these signal strength readings actually mean?
    >
    > Thanks.
    >


    The numbers are in -dbm, decibels below one milliwatt on the antenna
    connector.

    0dbm = 1mw
    -10dbm = .1mw
    -20dbm = .01mw
    -30dbm = .001mw or 1 microwatt
    every 10 db = a factor of 10.
    every 3 db = a factor of 1/2.
    the m is the reference point of a milliwatt.

    Your cable box uses dbmv, decibels below 1 millivolt
    In voltage, instead of power,
    20dbv = X10
    40dbv = X100
    6dbv = X2
    negative divides instead of multiplies.

    So, as you can see, -40 dbm would be .0001mw .1microwatts, a very high
    signal level for a receiver, which are all capable of receiving -110dbm
    these days way down in the noise floor.

    The actual signal level is unimportant, in itself, until it is compared
    to the actual NOISE level the system must operate in. This noise level
    varies greatly under different conditions.......how many other phones
    are all blasting away yours can hear, how hot the parking lot your
    walking across is from the sun. The sun itself is a huge RF generator
    making an incredible amount of noise, even though it's 93,000,000 miles
    away. Everything is much quieter at night. No sun noise, the hot metal
    items of the day's heat have cooled off and radiate substantially less
    noise.

    The term "signal-to-noise ratio", also expressed in the log db scale is
    the key. If you have a signal that's 1000 times the strength of the
    noise floor, you have a 30db signal-to-noise ratio. That's a great
    signal and will work fine, ___USUALLY___. The higher the S/N the better
    until it gets so strong it destroys the receiver's sensitive
    preamplifier front end at the antenna.

    The other consideration none of these numbers tells you anything about
    is called multipath propagation. Signals coming into your receiver (and
    the cell tower's receivers going the other way) are not all straight
    line direct signals. Signals bounce off conductive objects like towers,
    bridges, mountains, tall buildings, airplanes passing overhead, even the
    wires over the streets. Remember UHF analog TV? Everyone remembers
    "ghosts", multiple pictures that were always to the right of the main
    picture on the screen. These "ghosts" were caused by signals arriving
    AFTER the main signal on the direct path to your analog TV. We scan TV
    from left to right, top to bottom like we read a book, except we scanned
    every other line to lower the flickering you perceived. So, the signal
    that took a LONGER path, going, say, from the TV transmitter to a
    skyscraper, bouncing off in all directions including towards your
    antenna, took a LONGER path and MORE time to arrive, microseconds more
    time shows up on the very rapidly scanning dot as a ghost signal to the
    right, "late" from the direct signal.

    On the old analog phones, multipath caused the fading in and out you
    heard in the headphone as you walked along the street talking to your
    honey. If the main signal wasn't really strong, she may have faded out
    entirely. The multipath signal arrived out-of-phase with the main
    signal cancelling out the main signal, sometimes entirely. You moved
    about 3 3/8" (1/4 wavelength on 850Mhz) and her signal got fully quiet
    and very strong as the multipath signal AIDED the weak direct signal.
    You used to be able to hunt for such a "hot spot" in a weak area.
    Unfortunately, digital put a stop to all that fading you could use to
    find the hotspot. Digital phones just dropped the call and their signal
    level meters are way too slow to let you find the best place in
    multipath to call.....

    In high speed data, the signal arriving late caused the data to be late.
    The faster the data rate, the worse it gets. When the main signal is
    going to a mark tone, the late signal might still have a space tone,
    completely confusing the modem decoding the tones into data for the
    computer....data errors just make it crash. Various schemes are used to
    correct the data errors with lots of error checking to some degree of
    success, but not infallible. Wifi only works at very high speeds when
    you're very close to the router transmitting to you as their data rates
    are much higher than sellphone data rates. That's why....

    If you're looking at the test page of a sellphone's hidden-from-the-
    customer data pages, there is also a quality number that is a
    representation of signal-to-noise and data error rates that's more
    important than just the signal level it also shows you. That little
    range extender only runs 10-20 milliwatts of power output and has a
    range like your home wifi router...about 100 feet or 20 feet past the
    first wall it encounters. It's not going to serve the
    neighborhood....by design.



    --
    Global Warming and Creationism are to science what iPhone 4 is to
    antennas...

    Larry
     
  4. Harry 

    Harry  Guest

    Re: Explanation, please, of signal strength...in easy to understandEnglish.

    On 7/9/10 1:50 PM, Larry wrote:
    > =?UTF-8?B?SGFycnkg76O/?=<naled24511@mypacks.net> wrote in
    > news:89og81FqkuU1@mid.individual.net:
    >
    >> I installed "RealSignal-CDMA" on my Verizon Inc, and with the network
    >> extender, I'm getting five bars and a signal strength of -45 while I

    > am
    >> on the same floor as the device.
    >>
    >> The coverage in my area isn't terrific. If I go outdoors to the end of
    >> the driveway, I'm no longer in range of the network extender, and the
    >> signal strength drops to -85/-90.
    >>
    >> Would someone be kind enough to offer up an explanation in layman's
    >> terms of what these signal strength readings actually mean?
    >>
    >> Thanks.
    >>

    >
    > The numbers are in -dbm, decibels below one milliwatt on the antenna
    > connector.
    >
    > 0dbm = 1mw
    > -10dbm = .1mw
    > -20dbm = .01mw
    > -30dbm = .001mw or 1 microwatt
    > every 10 db = a factor of 10.
    > every 3 db = a factor of 1/2.
    > the m is the reference point of a milliwatt.
    >
    > Your cable box uses dbmv, decibels below 1 millivolt
    > In voltage, instead of power,
    > 20dbv = X10
    > 40dbv = X100
    > 6dbv = X2
    > negative divides instead of multiplies.
    >
    > So, as you can see, -40 dbm would be .0001mw .1microwatts, a very high
    > signal level for a receiver, which are all capable of receiving -110dbm
    > these days way down in the noise floor.
    >
    > The actual signal level is unimportant, in itself, until it is compared
    > to the actual NOISE level the system must operate in. This noise level
    > varies greatly under different conditions.......how many other phones
    > are all blasting away yours can hear, how hot the parking lot your
    > walking across is from the sun. The sun itself is a huge RF generator
    > making an incredible amount of noise, even though it's 93,000,000 miles
    > away. Everything is much quieter at night. No sun noise, the hot metal
    > items of the day's heat have cooled off and radiate substantially less
    > noise.
    >
    > The term "signal-to-noise ratio", also expressed in the log db scale is
    > the key. If you have a signal that's 1000 times the strength of the
    > noise floor, you have a 30db signal-to-noise ratio. That's a great
    > signal and will work fine, ___USUALLY___. The higher the S/N the better
    > until it gets so strong it destroys the receiver's sensitive
    > preamplifier front end at the antenna.
    >
    > The other consideration none of these numbers tells you anything about
    > is called multipath propagation. Signals coming into your receiver (and
    > the cell tower's receivers going the other way) are not all straight
    > line direct signals. Signals bounce off conductive objects like towers,
    > bridges, mountains, tall buildings, airplanes passing overhead, even the
    > wires over the streets. Remember UHF analog TV? Everyone remembers
    > "ghosts", multiple pictures that were always to the right of the main
    > picture on the screen. These "ghosts" were caused by signals arriving
    > AFTER the main signal on the direct path to your analog TV. We scan TV
    > from left to right, top to bottom like we read a book, except we scanned
    > every other line to lower the flickering you perceived. So, the signal
    > that took a LONGER path, going, say, from the TV transmitter to a
    > skyscraper, bouncing off in all directions including towards your
    > antenna, took a LONGER path and MORE time to arrive, microseconds more
    > time shows up on the very rapidly scanning dot as a ghost signal to the
    > right, "late" from the direct signal.
    >
    > On the old analog phones, multipath caused the fading in and out you
    > heard in the headphone as you walked along the street talking to your
    > honey. If the main signal wasn't really strong, she may have faded out
    > entirely. The multipath signal arrived out-of-phase with the main
    > signal cancelling out the main signal, sometimes entirely. You moved
    > about 3 3/8" (1/4 wavelength on 850Mhz) and her signal got fully quiet
    > and very strong as the multipath signal AIDED the weak direct signal.
    > You used to be able to hunt for such a "hot spot" in a weak area.
    > Unfortunately, digital put a stop to all that fading you could use to
    > find the hotspot. Digital phones just dropped the call and their signal
    > level meters are way too slow to let you find the best place in
    > multipath to call.....
    >
    > In high speed data, the signal arriving late caused the data to be late.
    > The faster the data rate, the worse it gets. When the main signal is
    > going to a mark tone, the late signal might still have a space tone,
    > completely confusing the modem decoding the tones into data for the
    > computer....data errors just make it crash. Various schemes are used to
    > correct the data errors with lots of error checking to some degree of
    > success, but not infallible. Wifi only works at very high speeds when
    > you're very close to the router transmitting to you as their data rates
    > are much higher than sellphone data rates. That's why....
    >
    > If you're looking at the test page of a sellphone's hidden-from-the-
    > customer data pages, there is also a quality number that is a
    > representation of signal-to-noise and data error rates that's more
    > important than just the signal level it also shows you. That little
    > range extender only runs 10-20 milliwatts of power output and has a
    > range like your home wifi router...about 100 feet or 20 feet past the
    > first wall it encounters. It's not going to serve the
    > neighborhood....by design.
    >
    >
    >


    Thanks...I actually understood a good portion of your post!
     
  5. Larry

    Larry Guest

    =?UTF-8?B?SGFycnkg76O/?= <naled24511@mypacks.net> wrote in
    news:89p6ajF32sU1@mid.individual.net:

    > Thanks...I actually understood a good portion of your post!
    >
    >


    Darn! I used to teach this stuff at a technical college......

    I used to be able to get it across to about 80-90%....

    I'm honored you were helped by it.....thanks.

    --
    Global Warming and Creationism are to science what iPhone 4 is to
    antennas...

    Larry
     

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