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  1.    #1  
    I am having problems with signal strength at my home on my treo 600. I checked TC FAQ's and did a check of the RSSI. I get a RSSI of between -93 and -101 on the house and outside the house I get between -90 and -96.

    The FAQ says -100 is borderline ( I have a Sprint toer a half mile form my house)...but is a less than 100 better or worse...ie -90 better than -105?, or worse?

    Thanks
  2. #2  
    The higher the number (the less negative) should be better. Aren't these numbers measured in dB or some related unit?

    Anyway, this would be consistent with your quick indoor/outdoor check. Right now I have two bars and have around -90. Two bars is generally plenty to get a stable connection on Sprint, for me anyway.
  3. #3  
    Once you go over -100 (i.e. 102, 104) you'll start to have lost packets and hear dropouts in your call. Anything over 105 and you'll probably drop your call.

    To give you an idea of a good signal, I was at the local highschool today and about 250ft from the tower and my signal was -63. At home, it's usually -90 to -100.
  4. #4  
    Decibels, dB, is a logarithmic scale. When talking about cell phones, it's usually measured in dBm- decibels relative to 1 milliwatt. Every 20dB is an order of magnitude, a power of 10. Positive dB indicate it's getting stronger, while negative dB indicate it's weaker- simply put, the larger negative, the smaller the decimal point.

    0 dBm = 1 mW (milliwatt)

    0 dB = 1
    -20 dB = 0.1
    -40 dB = 0.01
    -60 dB = 0.001
    -80 dB = 0.0001
    -100 dB = 0.00001

    Every 3dB means about half the power.

    So, a -100dBm signal strength means a hundred-thousanth of a milliwatt is recieved. By -120dB or so, the background noise is typically louder than the transmitted signal, and it gets drowned out, but this is variable on the EMI environment you're in. In clear air, the signal dissipates as the inverse square- twice the distance means 1/4th of the power; but in real-world terms, walls, buildings and terrain features usually dominate the loss. Antenna design and orientation can make a big difference, too!

    For analog, the weaker signals will sound like crap. But as it's all digital anymore, strength doesn't affect call quality until the phone can't tell 1s from 0s; so as long as you're recieving *any* strength at all, the call will be crystal clear -80 to -100dBm is common and based on people's reading here, usually OK. Of course, the weaker the signal, the more power your phone has to pump out to get the signal back to the tower, and the shorter your battery will last.

    A cell phone pumping out 300mW would transmit about +50dBm, btw. The best signal I've ever heard of anyone recieving is a -8dB signal, but then, I've only recently been paying attention
    Last edited by SteveFehr; 08/08/2004 at 01:31 PM.
  5. #5  
    Cool. I've been trying to find the full technical explaination of how RSSI is measured, though I had only come across incomplete explainations.. until now.

    Thanks!
  6.    #6  
    Thanks for the info!

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