Let the games begin!
in [Wireless Internet]
|
From: Jeff Liebermann on 4 Jul 2010 00:13 On Sat, 03 Jul 2010 19:12:56 -0400, "Richard B. Gilbert" <rgilbert88(a)comcast.net> wrote: >That makes sense! Any antenna intended for use by a transmitter must be >carefully matched to the transmitter. Yep. In the case of the iPhone 4, there are two antennas. <http://www.anandtech.com/show/3794/the-iphone-4-review/2> The small one has to do just 2.4Ghz. The larger one has to do 800, 900, 1800, and 1900MHz. Matching a single frequency is easy. Matching a wide range of frequencies is not. >If carefully done, most of the >transmitter's signal is radiated which is what you want. Radiating all the signal (efficiency) is only part of the problem. The RF needs to radiate away from the users brain in order to meet the FCC SAR (specific absorption rate) limit. <http://www.anandtech.com/show/3794/the-iphone-4-review/2> Oh wait... the user bought an iPhone 4, so the brain is already presumed damaged. -- Jeff Liebermann jeffl(a)cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558
From: Jeff Liebermann on 4 Jul 2010 00:35 On Sat, 03 Jul 2010 20:59:37 -0700, nospam <nospam(a)nospam.invalid> wrote: >some users report call drops on the iphone 4 and others don't. The AnandTech review showed a -24dB max drop in signal level when the phone is improperly held: <http://www.anandtech.com/show/3794/the-iphone-4-review/2> That's huge. That's about a 1/250th decrease in signal. As the author indicates, if the phone has a fairly strong signal to start with, it won't drop the call. However, if the signal is modest or weak to start with, a -24dB decrase will drop the call. I never saw anything near -24dB drop when fondling the antennas on various cell phones. My first guess was too high an antenna Q. I then guessed VSWR shutdown. Maybe my first guess was right? >you'll be disappointed to learn that the iphone 4 has removed field >test mode. Yep. I'm not surprised. AT&T got severely embarassed when Verizon published the real map of their 3G network. Since they can't build the network fast enough, might as well remove the tools needed to attach numbers to the coverage. Apple: You don't need to know. AT&T: We don't want you to know. >that's the thing, people want to see bars, but it really doesn't mean >much. i've had successful calls with 1 bar and i've had drops with 5 >bars. I suppose if this becomes a trend, the range from 1 to 5 bars will be from minimum detectable signal, to where the BER goes flat line. Anything over that gets 5 bars. Reading the description in the above URL, that appears to be what's happening in the iPhone 4. >the takeaway from that is there are many factors that contribute to a >call drop, and also that it's really hard to do a controlled >experiment. Yep. Worse, when the system is really busy, like during rush hour, VZW will drop calls that have been running for over 10-15 minutes to make room for new callers. I suspect the other service providers are doing something similar. It's really difficult to tell what caused a call to drop from the handset end. -- Jeff Liebermann jeffl(a)cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558
From: nospam on 4 Jul 2010 00:42 In article <gp2036pkfqgq665djupris1ps6a9msh37q(a)4ax.com>, Jeff Liebermann <jeffl(a)cruzio.com> wrote: > >that's the thing, people want to see bars, but it really doesn't mean > >much. i've had successful calls with 1 bar and i've had drops with 5 > >bars. > > I suppose if this becomes a trend, the range from 1 to 5 bars will be > from minimum detectable signal, to where the BER goes flat line. > Anything over that gets 5 bars. Reading the description in the above > URL, that appears to be what's happening in the iPhone 4. showing ber on the main screen would be very useful. my old touchpoint phone showed ber in test mode and actually had the most informative test mode i've ever seen, with 2-3 pages of data including cells it was talking to and the ones to which it was considering switching. > >the takeaway from that is there are many factors that contribute to a > >call drop, and also that it's really hard to do a controlled > >experiment. > > Yep. Worse, when the system is really busy, like during rush hour, > VZW will drop calls that have been running for over 10-15 minutes to > make room for new callers. I suspect the other service providers are > doing something similar. are you referring to cdma cell shrinkage? that is *really* hard to explain to people. > It's really difficult to tell what caused a > call to drop from the handset end. right, and people are blaming the iphone antenna, without having ruled out other causes.
From: Todd Allcock on 4 Jul 2010 00:34 At 03 Jul 2010 16:38:49 -0700 nospam wrote: > In article <vBPXn.6752$Lj2.1476(a)newsfe05.iad>, Todd Allcock > <elecconnec(a)AnoOspamL.com> wrote: > > > I like that meter. My HTC-built Sony X1 (great PDA, terrible phone) > > switches from 5 bars to 4 at -90 dbm. That's a meter designed to "hide" > > a lousy phone! Consequently, I get very little warning before losing > > signal entirely. The bars drop from 5 to 0 rather quickly in weak areas. > > they're deceiving you. time for a lawsuit. :) Thankfully, HTC includes a Field Test app with their devices. I'm only a few taps away from knowing what the score is, regardless of what the bars say.
From: SMS on 4 Jul 2010 01:23
On 03/07/10 9:35 PM, Jeff Liebermann wrote: > On Sat, 03 Jul 2010 20:59:37 -0700, nospam<nospam(a)nospam.invalid> > wrote: > >> some users report call drops on the iphone 4 and others don't. > > The AnandTech review showed a -24dB max drop in signal level when the > phone is improperly held: > <http://www.anandtech.com/show/3794/the-iphone-4-review/2> > That's huge. That's about a 1/250th decrease in signal. As the > author indicates, if the phone has a fairly strong signal to start > with, it won't drop the call. However, if the signal is modest or > weak to start with, a -24dB decrase will drop the call. I never saw > anything near -24dB drop when fondling the antennas on various cell > phones. My first guess was too high an antenna Q. I then guessed > VSWR shutdown. Maybe my first guess was right? > >> you'll be disappointed to learn that the iphone 4 has removed field >> test mode. > > Yep. I'm not surprised. AT&T got severely embarassed when Verizon > published the real map of their 3G network. So much so that they launched a bogus lawsuit against Verizon. |