**2.2. INS**

Inertial measurement unit platforms are increasingly being used integrated either with other instruments, typically GNSS, odometers, and magnetometers, or with storage units [34]. They then form an inertial navigation system (INS).

In general, INS instruments are comprised of three accelerometers, three gyroscopes, and three magnetometers. The characteristics of these sensors are briefly described.

Accelerometers are instruments that measure acceleration (the rate of change in velocity), and help the phone distinguish up from down.

All accelerometers have two fundamental parts:


For example, let us assume a spring and a heavy ball. If you move the housing up, the ball lags behind stretching the spring. If we measure how much that spring stretches, we can calculate the force of gravity.

Gyroscopes are sensors that can provide orientation information as well, but with greater precision. Thanks to this particular sensor, Android's Photo Sphere camera feature can tell how much a phone has been rotated and in which direction.

The digital compass is normally based on a sensor called magnetometer, which provides a simple orientation in relation to the Earth's magnetic field. Consequently, every smartphone knows where is North so it can autorotate the digital maps depending on its physical orientation.

#### **2.3. Cameras**

Like GPS/GNSS chipset, camera sensors are mandatory components for any kind of massmarket communication device and in particular for smartphones. CMOS image sensor (CIS) has always been one of the most important features in our phone, so that it was able to move the market to a new category of smartphones, the so-called camera phones. Google Pixel, Apple iPhone 7 Plus, Samsung Galaxy S7, Huawei P9, and Sony Xperia X are some of the best camera phones according to the international mobile industry congress like the International Consumer Electronics Show (CES) 2017 in Las Vegas and the Mobile World Congress (MWC) 2017 in Barcelona.

The mobile image sensing is the more direct way for the commercial user to represent the reality, to share information, and to create social interactions. For these reasons, in the last years, the CIS market has put particular emphasis on the quality of the camera modules, reaching high resolution levels, and makes them usable as low cost tools for numerous applications. Jointly with the numerous embedded sensors, like gyroscope, accelerometer, proximity sensor, GPS receiver, and Wi‐Fi connectivity, these new camera chipset have boost the effort in R&D for new kind of applications like 3D sensing technology, such as Google's Tango, automotive self-drive, drone product, and virtual and augmented reality. Numerous technological upgrades in chipset architecture, like backside illumination (BSI) and in-sensors setups, like the dual camera implementation, have moved the market in favor of company rather than another. Nowadays, production and technology leader of image chipsets is Sony, covering 35% of the entire market. Sony's sensors are mounted into numerous smartphones and tablets like the Samsung Galaxy S7, Huawei P9, Sony Xperia X, etc. After, there is Samsung (Samsung Galaxy S7, Lenovo Vibe Shot) and Omnivision (Huawei P8, Lenovo K3 Note) and, according to many CIS market research firms, all three together reach about the 70% of the world market.

CMOS stands for complementary metal-oxide semiconductor, and it uses the same manufacturing technologies of CCDs sensors, the dominated technology till now, but needs much less power and the production is less expensive. The main advantages of CMOS imagers are that they are compatible with mainstream silicon chip technology and this allows on-chip processing and consequently the miniaturization. With the technological development on the semiconductor industry, the gap between CCD and CMOS has narrowed and the quality of the obtained image is competitive.

A typical CMOS is an integrated circuit with an array of pixel sensors and has the following main part:

• Micro lenses

pseudoranges and carrier-phase measurements from smartphones with Android 7.0 OS. The announcement came from Google during the I/O 2016, the 3-day developer conference which took place from 18 to 20 May. It is a very strong innovation, destined to bring a revolution in the field of survey and geo‐localization: with these kinds of sensors, accuracies of few centimeters will be obtainable even with mobile devices. Despite that, this kind of possibility will

Inertial measurement unit platforms are increasingly being used integrated either with other instruments, typically GNSS, odometers, and magnetometers, or with storage units [34]. They

In general, INS instruments are comprised of three accelerometers, three gyroscopes, and

Accelerometers are instruments that measure acceleration (the rate of change in velocity), and

For example, let us assume a spring and a heavy ball. If you move the housing up, the ball lags behind stretching the spring. If we measure how much that spring stretches, we can calculate

Gyroscopes are sensors that can provide orientation information as well, but with greater precision. Thanks to this particular sensor, Android's Photo Sphere camera feature can tell

The digital compass is normally based on a sensor called magnetometer, which provides a simple orientation in relation to the Earth's magnetic field. Consequently, every smartphone knows where is North so it can autorotate the digital maps depending on its physical

Like GPS/GNSS chipset, camera sensors are mandatory components for any kind of massmarket communication device and in particular for smartphones. CMOS image sensor (CIS) has always been one of the most important features in our phone, so that it was able to move the market to a new category of smartphones, the so-called camera phones. Google Pixel, Apple iPhone 7 Plus, Samsung Galaxy S7, Huawei P9, and Sony Xperia X are some of the best camera phones according to the international mobile industry congress like the International Consumer Electronics Show (CES) 2017 in Las Vegas and the Mobile World Congress (MWC)

three magnetometers. The characteristics of these sensors are briefly described.

**1.** A housing attachment to the object whose acceleration we want to measure.

not be analyzed in this chapter.

166 Smartphones from an Applied Research Perspective

then form an inertial navigation system (INS).

help the phone distinguish up from down.

All accelerometers have two fundamental parts:

**2.** A mass that, while tethered to the housing, can still move.

how much a phone has been rotated and in which direction.

**2.2. INS**

the force of gravity.

orientation.

**2.3. Cameras**

2017 in Barcelona.


Looking at the best camera phone of 2017, it is possible to state the specification of the camera sensors and make an overview on the best characteristics. **Table 1** resumes some smartphone camera specifications.

More details about cameras are available at the following hyperlinks:



**Table 1.** CMOS image sensor characteristics for commercial camera phones.

