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Android vs. iPhone 4 Signal Strength Bars Comparison
thisisauniqueid writes "In light of the clamor over the iPhone 4 Grip of Death, AnandTech recently reverse-engineered the phone's signal-strength-to-bars mapping. Because Android is open source, we can determine the corresponding mapping for Android in combination with the 3GPP spec referenced in the source, allowing the signal-strength-to-bars mapping for both Android and the iPhone 4 to be plotted on the same axes. This shows that the iPhone 4 consistently reports a higher percentage signal strength (as defined by the fraction of bars lit) than Android GSM devices at the same signal strength."
The actual signal is amplified across most frequencies by an obscure side effect of the reality distortion field. If you were an Apple antenna engineer you'd know that.
All mobile phones have tradeoffs in antenna design in order to look pretty, because people don't like visible external aerials. Apple have come up with what should be a very good design but compromised it by not coating the metal in a dielectric layer. Apple have created bad publicity for themselves by coming up with a BP-like response to the complaints, but this won't affect their sales because Apple buyers don't take any notice of negative publicity for Apple products.
From scarped cliff or quarried stone she cries "A thousand types are gone, I care for nothing, no not one."
my wife's iphone constantly reports 3-4 bars and 3g in places where my motorola milestone reports 1 or no signal. it's not until she goes to make a call that -- oops! no coverage.
Probably 99% of the population has no idea that -80 dB is extremely good and -100 dB is awful. Further, the curve is logarithmic, which makes things confusing because most people are only particularly familiar with linear.
After I got my iPhone 3G the very next software update included a change to the "bar algorithm" that was marketed as "improving user understanding of the signal meter" or somesuch. It was in response to user complaints of low signal strength, and somehow (miraculously) the reception improved... more bars.
So they're rolling back this change?
MJC
IANARFEE, but I am a EE who works with RF.
For all of the millions of dollars being lost on productivity aimlessly discussing 'bars'..
Can someone please dissect the antenna and then connect it to a calibrated spectrum analyser? This is so mindbogglingly trivial to do it is beginning to hurt my soul. I do similar exercises at work with new, untested antenna designs. I am sure I am not the only one.
For comparison, do the same to other phones and publish actual measurements of received signal drops and the effect from the disturbance caused from closing your hand around the antenna. This is similar to how touching an old rabbit-ears style antenna effects the picture on a analog TV broadcast, if the effect is as I suspect.
Voila! An actual, meaningful assessment of what the phone bars mean in real numbers from a calibrated instrument.
An uncalibrated receiver, such as the iphone, is not a proper tool to do this.
*grumble* *off my lawn* *grumble*
..don't panic
An alternative could be to have it show a percentage between 0 and 100. As this might be too distracting perhaps just show them in groups of 20% each. To save space, you could leave out the number and just show a block.
That way you can easily show the strenght of the reception and made it understandable for everybody.
Don't fight for your country, if your country does not fight for you.
You're sort of right.
-174dBm/sqrt(Hz) is the minimum that you can achieve at "noise room temperature" (290 Kelvin), because that is the spectral density of noise in the RF region that a black body will emit. But every component from the antenna, antenna switch, low noise amplifier, downconverters, filters, more amplifiers, and ADC's will add a certain amount of noise to degrade the signal further. This can be discussed as noise factor, noise figure, noise temperature, and so on, but those are all also equivalent to having an increased noise floor at the signal reaching the antenna, and by converting to input referred noise floor, the minimum detectable signal is often defined as the point where the signal power equals the input referred noise power.
This will definitely NOT be the same for all phones.
A very good cryogenic low noise amplifier like astronomers use for very sensitive radio telescopes might have a noise temperature of 5 Kelvin, corresponding to an addition of -191.5dBm/root(Hz) noise power at the input. However the low noise amplifier in a cell phone probably has a noise temperature around 75 Kelvin (1dB noise figure at room temp), adding -179.7dBm/root(Hz) noise power. The first amplifier would be able to detect a signal 15 times smaller because of its superior noise performance. In fairness though it probably costs about a thousand times more...