Let the games begin!

I bet you haven't actually logged and tracked your experiences.

Your phone will go from 3 bars to no bars sitting on a table, not moving, with NO ONE touching it. Case or no case.

It has nothing to do with you and how you hold the phone, and everything to do with....AT&T.

Reply to
Elmo P. Shagnasty
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It can be normal for signals bars to fluctuate even when not touching the phone or moving. Some phones, for example, will switch back and forth between the signal strength of home and foreign networks. This can be very frustrating when a foreign network has a good signal and the home network has a poor signal, but the phone is only allowed on the home network.

Reply to
John Navas

True. Samsung has a sticker on some of their models warning users to keep their hands off the bottom of the phone. However, that wasn't my point. However, there's a difference between these phones and the iPhone 4. All of these phones will experience some reduction in signal strength (which causes a corresponding increase in TX power on the handset and cell site to compensate). Except in really really weak and marginal areas, I've never had a disconnect when grabbing the antenna on any of my phones (extendable or otherwise). Yet, the iPhone 4 causes a disconnect, which suggests that the signal loss is far more drastic than what has been observed on these other phones.

It varies by chipset. Both RSSI and SNR are available. I'm fairly sure the bar graph uses RSSI.

I don't use bars. I use the signal strength and SNR (Eb/No) provided by the field test mode.

In phone mode dial *3001#12345#* then press CALL. The Field Test Screen will appear. Select Cell Information. Signal Strength is on the top line after RX-. Frequency follows FQ and is based on the channel number (i.e. 100-200 is 800 MHz and 500-700 is 1900MHz). The top line displays information about the tower you are using. The lines below display info about your neighboring towers.

I just tried the covering hand test with a Motorola RAZR V3M on Verizon. Signal level dropped -6 to -9dBm when covered by my hand. That's about 1 bar and maybe 2 bars drop.

Incidentally, long ago, in a cell phone store long gone, I was standing in line waiting to ask some dumb question of the salesman. Ahead of me was the salesman and a lady looking at various phones spread around the table. Undecided as to which one to purchase, the salesman suggested picking the one with the largest number of bars. Over the years, the manufacturers and service providers have known about this effect, and tend to tweak the RSSI to bars conversion table to make more bars appear. My Verizon XV6700 would work just fine with no bars showing. Some other phones I've tried wouldn't work with 1 bar showing.

What I did to measure mine was attach an external antenna to the phone, and bury the phone inside a home made shielded enclosure. I then used a step attenuator in the antenna line to adjust the signal level. The signal level in -dBm would change rather rapidly, while I had to wait perhaps 10 seconds for the bars to change. There was considerable guesswork involved, but I think I was close.

Yet another dBm to bars table:

Oh rubbish. Just because it indicates 1 bar doesn't mean the signal is near the noise floor. Ask the author to supply some signal levels in dBm (and SNR) for a decent minimum usable level comparison. Incidentally, it's rarely the receiver in the handset that limits range and reliability. It's the receiver at the cell site, that has to handle overload from other sites, large dynamic range, and considerable multipath, while retaining decent sensitivity, that usually limits performance. The cell site xmitter can crank up the TX power to 1 or 2 watts (depending on band), while the typical handset can deliver maybe 100mw on a good day with a charged battery. Any more and users will be complaining that the battery doesn't last.

True. It has an effect, but it probably did NOT cause a disconnect.

Reply to
Jeff Liebermann

Case in point: the T-Mobile/Microsoft/Danger/Sidekick data-loss fiasco not that long ago. Has all that lost data been reconstructed yet?

Cheers, -- tlvp

Reply to
tlvp

some users report call drops on the iphone 4 and others don't.

it depends on the phone. i know my old denso touchpoint displayed snr (and a fantastic phone).

you'll be disappointed to learn that the iphone 4 has removed field test mode. anandtech managed to hack a level indicator back (but not the full field test mode) in by restoring a jailbroken backup which had some preference tweaked.

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.

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.

nevertheless, his experience is as valid as anyone elses, and he found reception to be better, and measured an increase in wifi strength when touching the antenna.

Reply to
nospam

$ snipped-for-privacy@news.eternal-

Yes, about a week after the server crash.

Of course that didn't make as many headlines as the loss did! ;)

The real problem with the Sidekick's method of "cloud computing" was that there was essentially no local storage- the data was on the cloud and phone only, with no backup.

A good cloud service, like Exchange, uses the cloud as an intermediary between devices, as well as a backup. I sync two mobiles and three PCs with my cloud service. If my provider crashes e or vaporates tomorrow, my data is safe in five locations, any of which can restore the data to another server/provider.

Reply to
Todd Allcock

Yep. In the case of the iPhone 4, there are two antennas.

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.

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.

Oh wait... the user bought an iPhone 4, so the brain is already presumed damaged.

Reply to
Jeff Liebermann

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.

Reply to
Todd Allcock

The AnandTech review showed a -24dB max drop in signal level when the phone is improperly held:

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?

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.

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.

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.

Reply to
Jeff Liebermann

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.

are you referring to cdma cell shrinkage? that is *really* hard to explain to people.

right, and people are blaming the iphone antenna, without having ruled out other causes.

Reply to
nospam

So much so that they launched a bogus lawsuit against Verizon.

Reply to
SMS

No, not CDMA cell breathing, although that could contribute to disconnects.

It's just an increase in the noise floor with CDMA causing a decrease in usable range.

What's happening is the Verizon got too many complaints about busy signals and incoming calls going directly to voice mail. Since the cell capacity could not be easily or economical increased without additional frequencies, Verizon opted to kick off the ratchet jaw yackers and allow new calls to have priority, when the system gets busy. That eliminated most of the busy signals. Meanwhile, those getting kicked off never suspected that the call was intentionally dropped, and probably guessed that they had driven through a weak signal area, or that a handoff had failed. It's possible that VZW is also dropping weak (low SNR) calls when the system gets busy, on the assumption that they're going to drop out anyway.

Reply to
Jeff Liebermann

AllCOCK?

Lemme see.

Reply to
Kimmy Boyer

Verizon: You think you know but the map's not accurate, in addition to being misleading about the difference between 3G and total coverage. (That's based on real experience comparing the map to actual coverage.)

On what do you base that? My friend at Verizon claims the real issue is cell "breathing".

Reply to
John Navas

Again, on what do you base that? My friend at Verizon claims the only real issue is cell "breathing".

Reply to
John Navas

It accomplished its purpose, cheap wide publicity of how misleading Verizon's ad were.

Reply to
John Navas

Yep -- HTC makes great phones, which is why Apple has decided it has to compete in court instead of just in the market. On my HTC phone: Menu >

Settings > About phone > Status > Signal strength (currently -89 dBm 12 asu).

Reply to
John Navas

Jeff Liebermann wrote in news: snipped-for-privacy@4ax.com:

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Here's your slot iPhone 4 antenna...nothing new...
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broadband antennas can be made for microwave frequencies from PC board material.

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Matching a wide range of frequencies isn't much of a challenge in 2010.

Placing the antenna where it will have a reasonable chance of radiating into space is becoming more and more of a political problem as the greenies take over the political system.

Reply to
Larry

Jeff Liebermann wrote in news: snipped-for-privacy@4ax.com:

Jeff, did you see the news where the Feds are going to give up another 500 Mhz for more wireless bandwidth?

It was on Google News midweek.

Reply to
Larry

nospam wrote in news:030720102142454132% snipped-for-privacy@nospam.invalid:

Ruling out other causes is very easy. Just pick up the cheapest free phone ATT sells and dial out a call right next to iPhone 4. Does the call work? Yes? Not the infrastructure or traffic's fault. That points it quickly at the real cause of failures.....iPhone 4's defective antenna system.

If Apple's gonna be in the radio business, they need to hire some radio engineers....

Reply to
Larry

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