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dbm stringth.. crazy

Discussion in 'Android General Discussions' started by tommy1984, Nov 29, 2013.

  1. tommy1984
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    tommy1984 New Member

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    dbm strength.. crazy

    ok So before i installed my wilison db pro I held a steady mid 90,s dbm signal, But now that I installed the amplifier, its all over the place Im talking about both 1x and 3G constantly jumping from-69 to -125 and every where in between, just jump, jump, jump, jump... and when it does settle down for a few minutes it is around the 80 dbm mark, then starts jumping again.. one second they can be reading -69 and another second its -125 the back to -71 and so on.. Does any one have any experience with these wilison products that might be able to shed some light on it for me?
  2. AECRADIO
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    AECRADIO Member

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    Are you placing the amp in an area with a clear path to the nearest tower?
    You may be experiencing what is known as ' multipath', which is actually the same signal reflected off multiple obstacles, such as buildings, water towers, Etc...
    Placing the main antenna in the highest location, but with a steady signal level will be the optimum location.
    Poor antenna placement can cause significant degradation as well as fluctuation of the tower's signals to your amp.
    Bi-directional amplifiers adjust the link power according to input signal levels, which will also cause automatic adjustments to your handset's RSSI display, indicating a rather poor location of the main antenna used by the amp, to connect to the 'outside world'.
    Tower sites can not always have solid signal levels, given the fact that man-made interference, as well as atmospheric and solar issues impact every RF signal, regardless of frequency.
    Try relocating the main antenna for a constant, solid and unfaltering signal strength indication. Watch this, and see if it changes rapidly, by how much, and over time.
    The stronger the signal level, the more 'level' the signal should remain, which will also level your phone's RSSI signal readings as well. The bi-directional nature of these amps, incorporate a receive amplifier to increase the gain into the amp, so a solid link is always maintained, no matter where you are, within reason.
    They are not designed to allow you to walk to a neighbor's house, for example, or run into a basement if your system is on a second floor, as the gain into the amp will be too poor to effect a proper handshake with the tower.
    Proper installation of these amplifier systems is paramount. Although you can use mobile antennas for the main (external) antenna, you should consider using a properly constructed collinear gain base station antenna, and use a magnet mount as the indoor link antenna for the RF link to your handset.
    The gain in both receive and transmit, is proportional to the RF signals the device is fed.
    Remember the old adage of: garbage in, garbage out.
    While the signal to the tower will (shouldn't) ever suffer, the signal into the amp, can, and often does, suffer.
  3. MotoXGirl
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    MotoXGirl New Member

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    You could also be simply hopping between multiple base stations.
  4. AECRADIO
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    AECRADIO Member

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    I doubt he is 'hopping' from one site to another, the 'FM capture effect' rules this issue.
    He may be experiencing issues from two sectors of the same tower, caused by signal reflection/refraction. Cell sites have multiple receive and transmit antennas (panels) on each sector, and with the advent of digital control and signal processing, most are electronically 'steered' to increase near-field coverage as well as distance. The old analog sites used to place a collinear antenna inverted at the tower site, the design of the antenna was such, that the beamwidth of the antenna allowed the mobile user to be physically closer to the tower and still maintain a link to the tower. This also had the added benefit of a cleaner hand-off to the next tower site the user 'roamed' onto.
    Two panel antennas from two different sectors of the same tower my be able to 'see' his phone, but the strongest of these will capture his receiver, forcing it to use that sector, even though his uplink to that same tower may not be the best, his receiver was captured by the weaker sector, and forced his phone to use the antennas with the poorest signal.
    Since you have a normal 45 mHz. difference in transmit to receive frequencies, what works well at 836.520 mHz. may not be the best at 881.520 mHz. You have a change in pattern densities due to frequency changes, which affect what the phone 'hears' in its receiver.
    My 1st channel 'B' is 384, which is 836.520, and the reverse of this is 1884, which corresponds to 881.520, not a huge change, but it can be enough to alter how the phone responds to commands it is sent, especially in urban environments, where you have a lot of tall structures nearby. Shadowing effects from the same tower, attenuation of signals from foliage and snow also play a part, as does weather and temperature.
    A simple test proves this quite simply. Find a known good location, note the signal strength in dBm, and take one reading in the morning, one in the afternoon, and one at night, look for weather changes and perfform the test again. You may not see a change if you are so close to a tower site, that regardless of weather and such, you always have a very strong signal, the test needs to be done on more distant sites you know you are being served by to make this a fair comparison.
    Driving in town, I bet you see fluctuations of signal, which is normal, caused by these very same issues.
    I will need to take some shots of active signals at both frequencies to show the visual differences of an 800 mHz. RF signal and the path loss suffered by same, in dBm.
    I may also need to perform this comparison at 900 mHz. as well, since my current equipment is only designed to cover to 1 gHz. I can cover enough of the tower sites I already service, so performing an accurate measurement should not be a problem.
    I hope Heinrich Hertz does not complain too loudly....