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Dots vs db signal strength inconsistent on Iphone 6

D

Derek87

macrumors 6502a
Original poster
Jan 29, 2009
693
160
so, i don't know if anyone is obsessed like me about signal strength, but i've noticed something peculiar since having my iPhone 6 (verizon) that i never hard with my previous iPhones on AT&T (5 and 4).

i don't see a consistent measurement between dots and db readings. i mean, the trend is right, but i had thought the dots were defined by db ranges.

for example, i recall on ios7 and my iPhone 5, -96db was 3 bars/dots.

well, i can have -114db on my iPhone 6, and sometimes if i flip the display to "dots," it will show 2-3 dots, and sometimes 1.

anyone else notice this? is there a reason for this?

also, i find the "dots" more optimistic overall than it was with the previous versions of iOS and my older phones. (-114db would always be one dot on my iPhone 5)
 
I have more practical experience with this other than owning phones. If I remember correctly, there was the big fiasco (from users) when Apple recalibrated their display to more closely represent what was actually happening.

I didn't say "signal strength" on purpose because I think Apple talked about that raw signal strength alone isn't used to calculate what the display shows. That's what I remember and I've learned to not rely on my memory. Based on your comments it would be time well spent for you to dig around a little big (unless someone smarter than me swoops in with a real answer). :)

But you are correct, before the software tweak the display was optimistic.
 
PNutts said:
I have more practical experience with this other than owning phones. If I remember correctly, there was the big fiasco (from users) when Apple recalibrated their display to more closely represent what was actually happening.

I didn't say "signal strength" on purpose because I think Apple talked about that raw signal strength alone isn't used to calculate what the display shows. That's what I remember and I've learned to not rely on my memory. Based on your comments it would be time well spent for you to dig around a little big (unless someone smarter than me swoops in with a real answer). :)

But you are correct, before the software tweak the display was optimistic.
Click to expand...
i do recall the whole fiasco when the iPhone 4 came out and antenna gate.

but what i'm referring to is that before ios8 and my iPhone 6, there was a pretty consistent 1-to-1 range for dots and dbm reading:

it was something like
< - 110db 1 dot
-100 to -110 2 dots
-90 to -100 3 dots
-80 to -90 4 dots
> -80dbm 5 dots

again, this is rough, but whatever its changed to with the iPhone 6 or iOS8, it's not consistent. it seems one day there is one "mapping," and another day, it is something else...
 
I was referring to the one time software recalibration of what the bars displayed verses actual signal strength. Sorry for the confusion. People that were getting 5 bars were then getting 4.

All I can say is that it's my understanding the dots shown are based on more metrics than just signal strength.
 
Steve686 said:
There was an update done to represent a stronger signal, not weaker. You could have the same -db numerical reading, but your bars would register more than before the update. I thought this was in the 3Gs era?
Click to expand...

i think this happened in IOS 4.1 (or 4.0.1), right after antenna gate...

what i'm referring to is the fact that something changed between ios7 and ios8, or some it seems... (i posted wondering if others had noted this oddity and change in behavior of the dots being a broader metric than just db signal or the mapping fluctuating a lot)
 
I believe the correlation between dots and db (aka rssi - receive signal strength indicator) scales with the different wireless protocol rssi ranges interpreted by the phone.

For example, if you're on GSM, the range ends near -113 dbm, UMTS ends near -116 dbm. On LTE it has a much wider range ending near -140 dbm.

I think it scales accordingly.

Also, aside from LTE, Verizon and AT&T share little else in common with it's core wireless technologies. You're probably detecting the subtle differences between CDMA and GSM that you were used to.
 
You are comparing apples to oranges. Just because you had 3 dots on an iphone 4 or 5, and 2 on an iPhone 6 does not mean the iphone 6 is weaker. You need to see what each phone is connecting to. Your iphone 6 is connecting to LTE while your other phones may be connecting to 3G or 4G. Your closest tower may only support 3G/4G thus appears stronger, while your 6 may be connecting to a tower further away that has LTE, thus the weaker signal. My iphone 6 plus when I switch to 3G get a signal of -90dBm at home, but when I switch to LTE it drops to -110 dBm. Thats because the tower that offers LTE is further away.
 
wxman2003 said:
You are comparing apples to oranges. Just because you had 3 dots on an iphone 4 or 5, and 2 on an iPhone 6 does not mean the iphone 6 is weaker. You need to see what each phone is connecting to. Your iphone 6 is connecting to LTE while your other phones may be connecting to 3G or 4G. Your closest tower may only support 3G/4G thus appears stronger, while your 6 may be connecting to a tower further away that has LTE, thus the weaker signal. My iphone 6 plus when I switch to 3G get a signal of -90dBm at home, but when I switch to LTE it drops to -110 dBm. Thats because the tower that offers LTE is further away.
Click to expand...

first, my iPhone 5 was an LTE phone and yes, i agree, it has different antennas. but what i was curious about was what the dots mean relative to dbm levels, not comparing my phones head to head, or even LTE vs 3G/4G-HSPA+

my experience is also similar to yours. i get higher signal strength measured by both dbm and dots in general for 3G and LTE suggesting that 3G coverage is much more dense than LTE.
 
andyw715 said:
how do you find the signal strength? is it some jailbreak thing?
Click to expand...

field test mode is available on all iPhones by dialing *3001#12345#*

you can make it your regular display too by holding down the power button until the "turn off dialog" comes up, followed by holding down the home button until it exits out.

(i'm sure there are clearer instructions on this around the web than what i've typed here :) )
 
Derek87 said:
field test mode is available on all iPhones by dialing *3001#12345#*

you can make it your regular display too by holding down the power button until the "turn off dialog" comes up, followed by holding down the home button until it exits out.

(i'm sure there are clearer instructions on this around the web than what i've typed here :) )
Click to expand...

This site had the basic breakdown of what you posted.
http://www.funkyspacemonkey.com/ena...th-iphone-5-iphone-5s-iphone-5c-running-ios-7
 
There is not a direct correlation from dBm to the amount of bars. It is a complex algorithm that takes a lot of other variables into consideration, such as SNR, the phone's transmit power, the tower's modulation type, the tower's transmit frequency, the signal's bandwidth, etc.

You may have 3 bars today at -100dBm and tomorrow that may only be 2 bars. There is a lot to factor in when determining how to tell the user how good of a signal they have.
 
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