Android vs. iPhone 4 Signal Strength Bars Comparison 253
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."
Re:noise floor? (Score:4, Informative)
The noise floor is around -174dBm/sqrt(Hz) depending on temperature.
This will be the same for all phones
dBm vs dB (Score:5, Informative)
In case you're wondering,the B is a Bel, which is a factor of 10. A dB is a deciBel, which is 1/10 of a Bel. dBm is decibels relative to a milliwatt of signal strength.
Two antennas! (Score:5, Informative)
The article is worth reading. Right on the first page it explains what is really going on with the "grip of death".
In other news reports I have seen about iPhone 4, it was explained that the iPhone 4 has a strip of metal wrapped around the body of the phone that serves as the antenna. Not so! There are two strips, of different lengths, serving as two antennas. One antenna is for WiFi and GPS, and the other antenna is for cell phone service. The "grip of death" happens when you make an electrical contact between the two antennas (on the lower-left corner of the phone).
According to the article, bridging the two antennas with your hand causes a drop in cell phone signal to noise ratio of about 24 dB. This can be enough to cause a dropped phone call, if you are already in an area with weak cell signal strength. If you are in an area with good cell strength, you won't drop the call and you might not even see the signal strength bars change.
And according to the article, as long as you don't bridge the two antennas, this phone really does do a better job of locking on to a weak cell phone signal.
So, if you have an iPhone 4, definitely invest in some sort of case that insulates the two antennas. And the article scolds Apple for not having put some sort of insulation over the antennas; presumably a future iPhone will do so.
Other pages of the article discuss other things. I did like the page where Anand explains why Apple's claims are valid that the screen is sharper than the human eye can resolve.
steveha
Err no... (Score:3, Informative)
They compared the percentage, not the number of bars. From the article:
The iPhone 4 consistently displays a greater percentage signal strength than Android (as defined by the fraction of bars lit).
Re:so what if the calculation is wrong (Score:3, Informative)
Re:noise floor? (Score:1, Informative)
Almost right... A good HEMT amplifier can have noise temperatures below room temperature. I have amps from Weinreb's group at CalTech that are about 70K noise at room temp at a few GHz.
Re:dB attenuation? (Score:3, Informative)
Good point. Well I'm running iOS4 jailbroken, and SBSettings has a panel which allows you to change those settings.
Swipe your finger across the top of the screen.
Press more.
Press Extra's and Options.
Turn Numeric Wi-Fi and Numeric GSM on.
Now you've got it showing the dB in place of bars, and once Apple releases the update for iOS4 to make this measurement accurate, I'll have a better idea of signal strength.
Re:Summarising... (Score:3, Informative)
Hmmm, I'm guessing that's irrelevant, since it's probably just the same signal attenuation that's present on every cellphone.
The issue on the iPhone4 is the ability to detune the antennas just by touching both the GSM/3G antenna and the WiFi antenna at the same time with a sweaty finger - something that could have been so easily prevented with a dielectric coating. That's the reason people should be pissed, but a lot of people seem to be confused about what's really the problem.
Re:Well duh ... (Score:1, Informative)
It's because we've broken ourselves from the chains you now call a warm fuzzy bed, and it feels good!