Mixed Signals
Any sufficiently advanced information is indistinguishable from noise
Tuesday 22 July 2008, 8:52 AM
iPhone 3G reception problems: your information, please
The one that's most interesting, because it can be measured, is lack of welly with 3G reception. It's famously difficult to characterise this because of issues like local blackspots, shielding from buildings, and network congestion - but according to this Apple support thread there is the chance of getting something approximating to actual data.
If you enter *3001#12345#*, you'll go into Field Test Mode, where one of the indicators is the signal strength in dBm, or decibel milliwatts. Anything below around -100 dBm is not good -- radio engineers, preferring consistency to clarity, work in negative numbers where 'higher' is in fact lower, so -80 dBm is a better signal strength than -105 dBm. (For reference, -90 dBm is one picowatt, giving you some idea how little power we're dealing with here).
if you're getting -100 dBm in an area where you'd normally expect decent O2 3G coverage, you have interesting information. It's even more interesting if you're on another UK network, but those results may take longer to appear.
Do let me know what you find. It's unlikely that the calibration on the iPhone is good enough for truly consistent results across units, but they should be close enough to get an idea.
PreviousComments on this post
hi rupert what is the route to the dbm menu there are there are 3 sections utmsinfo, utms rr mesurement and neighbour cells.
Signal strength is all related to mobile towers proximity. There is a bug in the contacts software being the biggest pain in 2.0 software and mobileme is just awful after 10 days.
Battery life is a daily charge if you really use the phone but email and net surfing are a joy and in a league of their own.
This comment has been deleted at the users request
The signal strength appears in tiny figures at the very top left of the display, just above the network ident ("O2-UK" in our case)
Hey Rupert
I haven't had time to try out the Filed Test Mode yet - maybe later today - but just based on watching the normal signal strength indicator, 02's coverage is definitely patchy.
I was sat in cafe yesterday afternoon - actually reading this post on my iPhone and watched as the indicator went from full and then dropped down to one bar and then back up to full again for no apparent reason. I guess being inside plays a part in this but the 3G service is definitely not as consistent as it should be.
I thought it was just me so now I know that there is recognised problem, I will try and catalogue my findings a bit more methodically...
-97 inbuilding (albeit within 5m of a window) in the City of London
