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My Samsung Galaxy Y (GT-S5360L) can run a wifi tethering network at 32 dBm, according to iwconfig. This is almost 2 watts. Is this reading accurate, (my battery is 1200mAh, 5v, or 6 watt hours, so it seems sort of fishy, but it does drain my battery really fast when I run it), and if it is, (assuming nothing blocking the signal) what is the range of the network in meters?

closed as off-topic by Izzy, geffchang, Dan Hulme, t0mm13b, onik Oct 18 '13 at 10:46

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    While I don't think the question is off-topic, I don't know that we on Android Enthusiasts will be able to give you a definite answer. I certainly don't know how to approximate the range of a wireless hotspot from its output power - and even if I did, there are specific paramaters we're missing. We don't know the antenna gain for your phone, for example. If we assume minimal antenna gain, we can say the power is around 32dB. – dotVezz Oct 17 '13 at 13:19
  • Googling for a formula to find signal loss over distance, I found this page: tp-link.com/en/support/calculator. I tried to use the formula on the page, but my assumptions for its use may be flawed because I came up with a value less than one meter (which seems entirely unrealistic... unless that's about what you're experiencing with your phone of course) – dotVezz Oct 17 '13 at 13:21
  • Just for the sake of more information: If we assume your antenna gain is around 12dB (Seems high though, I'm not familiar with this stuff), then the formula gives you almost 2 meters. – dotVezz Oct 17 '13 at 13:25
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32 dBm equates to 1584.89mW according to this calculator: http://www.radiolabs.com/stations/wifi_calc.html Assuming a 12 DBi Antenna Gain from the comments above, that gives us 44 dB of antenna power. The signal loss for 2400 MHz/Km is 100.03dB, citing the same site.

At the assumed 44dB of power, we'll round and say .044Km which is ~144 feet. Since throughput is inversely related, You're going to have a pretty poor download speed at 144 feet, barring there's nothing between the phone and the computer, on a clear day.

This is half guesswork, but hopefully it helps.

  • Thanks for referencing my comment! Your numbers sound much more realistic than mine (I saw that calculator too, but couldn't make heads or tails of it lol). Please note that it's probably not actually 12dB gain on a mobile antenna - that just seems way too high to be realistic - I just used 12db as kind of a "What if" situation. – dotVezz Oct 17 '13 at 15:15
  • Oh, there's one important thing to note here. Signal loss over distance isn't as simple as "100.04dB/KM". This is due to the logarithmic nature of dB. (20dB is 10x more than 10dB. 30dB is 100x more than 10dB). To demonstrate this, try plugging 5KM into that calculator. You get 114.01. That site is actually using the same formula that I used (Which kinda weirdly confirms my unrealistic numbers) loss (in dB) = 20log10(distance in km)+ 20log10(frequency) + 32.44 – dotVezz Oct 17 '13 at 15:19
  • Signal loss at 0.044KM using that model would be 72.9dB, significantly higher than the 32 (or 44dB) we're assuming he can pump out. – dotVezz Oct 17 '13 at 15:21
  • Of course, I can't really say that either of us are right or wrong with any authority. – dotVezz Oct 17 '13 at 15:22
  • My experience comes with CATV. Not exactly the same. The frequencies are much lower, but the numbers seemed right, in theory. – underscorenorm Oct 17 '13 at 15:41

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