Last week we commented that the iPhone 5s motion sensor is poorly calibrated and that, therefore, the device has a significant gap. Behold, Eagle Jones (PhD and CEO of RealityCap) offered a possible explanation for this. I already say that the subject is highly technical – for the most knowledgeable of the subject, I suggest reading Jones’ full post to capture all the details.
Image credit: Gizmodo US.
In short, the accelerometer is to blame. On iPhones of past generations, Apple used a sensor from STMicroelectronics (LIS331DLH); now, on the iPhone 5s, the company has switched to one from Bosch-Sensortech (BMA220). According to Jones, two things matter in this piece of hardware: noise density (noise density) and bias (bias). The noise density of the Bosch sensor is very similar to that of STMicroeletronics; the bias, no.
Jones explains that the typical measurement of the STMicroelectronics accelerometer bias is +/- 20mg (milli-g, or one thousandth of standard gravity), while that of the Bosch sensor is +/- 95mg. All of this was confirmed by tests performed by him – translating, +/- 20mg represents a difference of -1 degree of accuracy in detecting the slope, so +/- 95mg matches the -5 degrees of inclination found by many consumers.
The good news is that developers can make up for this gap by incorporating a calibration process within their apps – RealityCap is working on code to make things easier. In addition, Apple would also be able to fix this through a software update – we hope it will happen in the not too distant future.
[via Gizmodo US]