We test out Steve Jobs' claims that all smartphones suffer from signal loss if held in the 'grip of death'.

In response to critisicm over signal problems on the iPhone 4, Steve Jobs claimed in a press conference that all smartphones have the same issue.

But do they? To see how common a problem antenna attenuation is, we took the iPhone 4 and five of its top smartphone competitors into the field to put Apple's claims to the test. Here's what we found.

How we tested

We tested five smartphones that compete with the iPhone 4: the HTC Nexus One, the HTC EVO 4G, the RIM BlackBerry Bold 9650, the Motorola Droid X and the Samsung Galaxy S. First we measured each model's signal strength when held normally. Then we tested each handset while holding it in its death grip - the position where our hand covered the phone's antenna most effectively.

Because signal loss has far more severe real-world implications in environments where cellular coverage is already poor, we decided to test in a weak signal environment.

We measured signal strength in decibels per milliwatt (dBm), a standard way of expressing the power of a radio signal in relation to 1 milliwatt. In high-signal areas - for example, in locations where a smartphone user stands close to a mobile mast - a signal measured at -51 dBm is the highest (and best) that can be achieved. In poor coverage areas, phones can connect and hold a call until the signal weakens to approximately -113, at which point the call drops and the network connection fails.

To measure the real-world implications of signal loss, we tested both data speed performance and voice call quality. For data speed, we used the FCC-endorsed Ookla www.ookla.com testing app to measure upload speeds and download speeds. We ran three consecutive speed tests on each phone at each location, and then picked the best upload and download speeds of the three.

The voice-call tests were more subjective. We placed calls to a common local number, listening for static, jitter, delay, dropped calls, or failure to connect.

We stress that these tests are informal, non-scientific and by no means definitive. Nevertheless, we believe that we got a very good look at the death grip in action, and a reasonably good idea of how legitimate Steve Jobs's statements at the Antenna-gate press conference were.

NEXT PAGE: Signal loss results

  1. We put different smartphones to the test
  2. Signal loss results
  3. Data download speeds
  4. Unlikely death grips