Radio engineer: Consumer Reports iPhone 4 testing flawed (u)

In response to the iPhone 4 technical findings reported by the consumer buying advice group, engineer Bob Egan observed on his own site that "Consumer Reports' [radio frequency] engineers should know better than to think they can run an engineering grade test for an issue like this in a shielded room. And certainly not one with people in it."

Egan explains, "To even reasonably run a scientific test, the iPhone should have been sitting on a non-metallic pedestal inside an anechoic chamber. The base station simulator should have been also sitting outside the chamber and had a calibrated antenna plumbed to it from inside the chamber.

"I have not seen Consumer Reports' claim directly that the finger effect reduces the iPhones sensitivity by 20db as reported elsewhere, but unless Consumer Reports connected to a functional point inside the iPhone that number is fantasy.

"Even the way they seem to have tested the change – by varying the base station simulator levels – seems to assume the iPhone receiver and/or transmitter operate in a linear fashion (the same way) across all signal strengths – bad assumption.

"Bottom line: from what I can see in the reports, Consumer Reports replicated the same uncontrolled, unscientific experiments that many of the blogging sites have done."

While there is little controversy surrounding the fact that some changes can be observed in iPhone 4 signal bars by holding the device a certain way, and that the signal strength may impact call quality and data transmissions speeds, Egan notes that it is not known "what part of this problem is Apple’s and what part is related to the AT&T network. And we don’t know how the observed effect is, or is not, similar to other devices.

"We also don’t know if placing a finger on the antenna bridge is detuning the antenna or detuning the receiver itself. And neither does Consumer Reports."

Reuters and other new agencies have jumped on the latest blog posting by Consumer Reports to suggest that the groups's refusal to "recommend" iPhone 4 with a special endorsement is actually a recommendation against buying the phone.

The report by Reuters described Consumer Reports' evaluation of iPhone 4 "critical" and a "poor review," despite the fact that iPhone 4 is the highest ranked smartphone in the group's mobile phone rankings. Consumer Reports does not appear to have "recommended" any smartphone model in its tests.

Update: Egan added in an email response, "Curiously the Consumer Reports 'engineers' seemed to have completely overlooked a potential very large new problem observation: you cannot measure the 'receiver' antenna problem by monitoring the output power of the phone as they did.

"Bridging the antenna gap so as to make cell phone receiver deaf (or more deaf) would normally cause the output power of the cell phone to go up to compensate, not down. Eg. the cell phone thinks its further away from the tower.

"If what we see in the video is true – the received single strength went down- it would suggest two things; 1) touching the gap is actually making the cell phone more sensitive – not less, or 2) the problem is not a calibration of the signal strength software calibration as admitted by Apple. Instead suggesting there is a malfunction in the cell phone power control system, or some other screwy situation.

"Of course if Consumer Reports did even a reasonable job of controlling the conditions of the test there would be some authoritative data. As I said, their work is not authoritative, and is on par with many 'blogger' tests, including my own 'trash can' tests cited elsewhere."