The iPhone 4's signal loss woes - caused, it seems, by the way people hold their handsets - is a software problem, Apple has claimed.

"We have discovered the cause of this dramatic drop in bars, and it is both simple and surprising," it said in an open letter to iPhone 4 buyers.

"Upon investigation, we were stunned to find that the formula we use to calculate how many bars of signal strength to display is totally wrong. Our formula, in many instances, mistakenly displays two more bars than it should for a given signal strength. For example, we sometimes display four bars when we should be displaying as few as two bars.

"Users observing a drop of several bars when they grip their iPhone in a certain way are most likely in an area with very weak signal strength, but they don’t know it because we are erroneously displaying four or five bars. Their big drop in bars is because their high bars were never real in the first place."

To fix the problem, Apple will release a software update "in a few weeks", it said.

"The real signal strength remains the same, but the iPhone’s bars will report it far more accurately, providing users a much better indication of the reception they will get in a given area," it added.

"We are also making bars 1, 2 and 3 a bit taller so they will be easier to see," Apple said, which sounds like its trying to subtly imply a weak signal isn't quite so weak after all.

So it's not just your hands the might be wrong - it's your eyes too...

But Apple insisted that the iPhone 4's wireless is "the best we have ever shipped".

Maybe it is, but that doesn't explain the drop off when you grip the handset. If the signal readout is incorrectly high, why does it cease to be so when the iPhone is held in a certain way? Why would the so-called 'grip of death' yield a more realistic signal reading?

No matter how the iPhone presents the signal strength, a drop off is a drop off, whether the fall is from five bars to one, or from two to zero.

Of course, it could be that other handsets give an over-inflated signal readout, making Apple's appear worse than they are. We're used to high signals from other phones so when the iPhone shows a lower signal we assume it, not previous handsets, is to blame.

And since signals fluctuate no matter what - the iPhone 4 untouched on the next to me has just gone from five bars to one and back up to four, for example - it can be hard to see where a handset's ability to pick up a signal ends and a network's ability to transmit one begins.

Still, Apple's proposal isn't as clear cut a solution as it seems, so we'll reserve judgement until the software patch arrives.

And if it doesn't work, we'll hopefully still be able to "return your undamaged iPhone to any Apple Retail Store or the online Apple Store within 30 days of purchase for a full refund". ®