re Engineer Claims Consumer Reports iPhone 4 Reception Problem Study Is Flawed - iPhone Hacks

[Dave Farber <dave () farber net>]

Begin forwarded message:

> From: "David P. Reed" <dpreed () reed com>
> Date: July 14, 2010 3:05:06 PM EDT
> To: dave () farber net
> Cc: ip <ip () v2 listbox com>
> Subject: Re: [IP] Engineer Claims Consumer Reports iPhone 4 Reception Problem Study Is Flawed - iPhone Hacks

> Two points made by Bob Egan, the "electromagnetic engineer" who disputes the claim, trouble me a bit.  Besides that, 
> his words seem to indicate that he has not actually read the Consumer Reports *report* itself.   A scientist would 
> not claim the testing was wrong if he had not studied the data first.  However, without trying to claim that Egan or 
> CR are right or wrong, here's what worries me about Egan's post (as quoted in the iphonehack site, there being no url 
> to his original).
>
> 1. the iPhone 4's *antenna* is actually on the outside of the phone, capable of coupling with the human hand.  There 
> is no dispute about that.  So why is Egan claiming that 20 dB of sensitivity reduction is "fantasy" because they 
> don't connect to a functional test point inside the phone?  Is he claiming that touching an antenna cannot cause 
> signal strength to drop 20dB or more?  I just tried grabbing an antenna firmly in my hand that is atached on a 900 
> MHz SDR receiver I happen to have set up in my lab at home, and the signal dropped as much as 40dB ...  Perhaps he is 
> just saying that he wants a more precise test to give the exact number?  What if it turns out to be 40 dB in some 
> cases and not 20 dB?  Was CR wrong in that case?
>
> 2. Much is made by Evans of the need for an anechoic chamber isolated from outside influences.   Hmm... do you use 
> your phone in an anechoic chamber?   Is your body (a conductive sack of salt water) not in contact with the phone?  
> What about the car you are sitting in when you use the phone?  Hmm... I think CR's test might have been *better* than 
> a "scientific" test in an anechoic chamber, or at least one could argue that.
>
> I'm sure that sensitivity tests with "functional test points" are done during manufacturing of the phone.  Presumably 
> the effect is not observed in the manufacturing process.  So repeating the same test done during manufacturing proves 
> nothing other than "the phone met its test specs".
>
> In the end of the day, science and engineering are not about experiments in the "lab".  We design products for and 
> study *reality*.  Labs are just ways to set up simplistic cases, and are quite useful for that - but most scientists 
> realize that to run a test in isolation risks missing really important effects, and most design engineers do also.
>
> On 07/14/2010 12:48 PM, Dave Farber wrote:
> > http://www.iphonehacks.com/2010/07/radio-engineer-claims-consumer-reports-iphone-4-reception-problem-study-is-flawed.html
> >
> >
> > Btw I have found no reception issues with my iPhone 4 with or without a case. I do find a face proximity problem 
> > infrequently 
> >
> > Dave
> >
> > -------------------------------------------
> > Archives: https://www.listbox.com/member/archive/247/=now
> > RSS Feed: https://www.listbox.com/member/archive/rss/247/
> > Powered by Listbox: http://www.listbox.com
> >
> >   



-------------------------------------------
Archives: https://www.listbox.com/member/archive/247/=now
RSS Feed: https://www.listbox.com/member/archive/rss/247/
Powered by Listbox: http://www.listbox.com