What technology enables a cell phone to be used as a hands free device?

The Latest Cell Phone Technology

The cell phone industry is one of the fastest changing in electronics. New products come out almost daily. And new features and capabilities are invented regularly to keep the technology fresh and the sales continuous. Here is a snapshot in time of the latest cell phone developments.

Femtocells

One of the most frustrating problems cell phone users have is poor coverage at home. Many homes are not located near cell sites or have poor indoor performance. This is maddening to many, especially those who want to give up their regular wired home phone and go only wireless. One solution to this problem is the femtocell. This is a small base station designed to be installed at home. The concept is illustrated in Figure 8.15. It can usually accommodate calls from up to four cell phones. The femtocell connects back to the carrier via your high-speed Internet connection, a DSL line, or a cable TV link. It provides great in-home coverage and has the added benefit that it offloads to the cell site and the carrier, providing more capacity to others.

Figure 8.15. Concept of femto cell.

Femtocells are just now becoming available but will soon be rolled out nationally. It is expected that the new LTE systems will make extensive use of femto cells.

Cell Phones

Cell phones can provide an inexpensive means of communications, particularly cell phones with a two-way radio function. They provide in a single unit both a two-way radio and the ability to call the police directly when needed, as well as managers.

Cell phones have limits, however. Before deciding on using a cell phone as a primary means of communication, it is important to conduct a test with the type of cell phone planned for use in every dark recess of the building, parking structure, stairwell, restroom, storage room, and throughout the entire facility. Otherwise, you may discover a dead spot in exactly the place where the worst possible emergency is occurring, exactly when it occurs.

Cell phones are particularly valuable for patrol officers in vehicles because of their wide geographical reach, allowing the officer to be reached both on and off the property.

Cell phones

Cell phones are handheld devices that allow people to communicate over a network. Originally only used for voice communication, today’s mobile phones provide additional services such as e-mail, Internet browsing, PDA (Personal Digital Assistant) functionality, digital camera, SMS (Short Message Service) for text messaging, games, and the ability to watch video or listen to music.

Cell phones present additional risks due to their smaller form factor and greater portability than laptops.

Cell phones used by an organization should have as much security as possible setup on the device.

If the cell phone supports a power-on password or has a key lock, which prevents the phone from being used unless a personal identification number (PIN) is entered, these features should be activated on the phone.

Data stored on memory cards used by cell phones should be encrypted if the phone software supports it.

Organizations should also decide whether to limit or prohibit the use of cameras on cell phones as a cell phone camera can be used to take pictures of sensitive data displayed on a screen or other classified information that may be displayed in plain sight.

Viruses have been written for cell phones and could be easily disseminated to cell phone users.

The first cell phone virus, Cabir, first appeared in 2004 and spread between cell phones that used the Symbian operating system by transmitting itself using Bluetooth.

Cell phones can be used as modems and can allow a computer to connect to the Internet without having to go through the corporate firewall. This could allow for the unauthorized transfer of data outside of the corporate network. Another method of transferring data is using Bluetooth technology.

Bluetooth is a wireless protocol and service that allows Bluetooth-enabled devices to communicate and transfer data with one another. It has a discovery mode that allows devices to automatically detect and connect with other devices. Without authentication, a person could connect to a Bluetooth-enabled cell phone or other device and download data.

Bluesnarfing is a term used for someone who leaves their laptop or another device in discovery mode, so that they can connect to any nearby Bluetooth device that’s unprotected.

6.2.2 Use of a Personal Digital Assistant

Cell phones are common communication devices nowadays; farmers and consumers will have individual cell phones. Many studies on using cell phones to realize traceability systems or more effective production systems have been reported. SEICA (http://seica.info) that follows the virtually identified produce system (Sugiyama, 2004) is a brochure on the internet. Using a cell phone, farmers can input information not only on crop production but also crop shipment. Cell phones are available to input and browse the system using both text and images; QR code and IC tags can assist farmers in accessing the system in the field with ease.

Acquiring cropping information is also possible using a cell phone. A mobile phone-based field data logger system for mandarin orange production has been reported (Kamiya et al., 2011). The system focuses on collecting data that can be used to determine the watering schedule for cultivation using drip irrigation. Automated field monitoring was performed using Field Server, which is a server computer installed in the field, and a sensor network to collect weather information. The results can be visualized as a timeline using a web-based system; users can compare their results with the data provided by other users, and can then consult with experts in their area.

Mobile phones

Cell phones are more modern tools compared to scanners or cameras dedicated to capturing images from μPADs. In addition, mobile phones are currently popular, globally affordable, lightweight, portable and they do not require tedious training (Baek et al., 2020; Tsao et al., 2021; Yu et al., 2015). Also, it is important to highlight that cell phones make possible the data transmission directly from the point-of-care to an external specialist, thus enabling the real chance to perform telemedicine (Martinez et al., 2008a). Nowadays, if commercially available, the association of mobile phones as electronic devices for image capture and paper-based devices could be very useful for monitoring coronavirus disease (COVID-19) outbreak (Kim et al., 2020; Navruz et al., 2013; da Silva et al., 2020; Wang et al., 2020b; Yoo et al., 2020).

The smartphone models contain integrated high-resolution cameras and they can be found at affordable prices. Cell phones offer a few values of merit over scanners based on aspects of portability (Roda et al., 2016). However, one of the biggest advantages of using cell phones for colorimetric detection is because specific Apps for this purpose have been created by the scientific community itself. These Apps allows image capture, data processing, and, in some cases, may even provide analytical responses (Nogueira et al., 2017). This integration has made possible a great advance in the use of smartphones for colorimetric detection (Fernandes et al., 2020; Morbioli et al., 2017).

One of the main demerits of the use of cell phones is the variations in image capture that include lighting conditions, image angle, shadows, and focal length, which contribute to the intra and inter-variability. These aspects can reduce the sensitivity of the method when compared to the scanner. However, different strategies have been used to solve or minimize these problems through the creation of supports and integrated parts to correct the luminosity, etc. (Fernandes et al., 2020; Morbioli et al., 2017).

Control for cell phone backlight, vibrator motor and sound

Cell phones use various combinations of vibration, sound and light to alert the users of an incoming call or message. Figure 290.3 illustrates a cell phone with four backlighting LEDs, a vibrator motor and a logic controlled sound device. A single logic pin, ENU, turns on all simultaneously.

If the vibrator motor requires more than 100mA, simply gang-up the ULED outputs to provide enough current. A small ceramic capacitor may be needed across the motor terminals and between the ULED output pins and ground to reduce inductive spikes and to prevent false dropout.

The speed and current in the motor is proportional to the voltage across the motor, so the voltage across the motor must be controlled in order to control the motor speed and current. One voltage-control method is to connect a shunt zener diode across the motor. Use a zener diode that provides the desired voltage across the motor with minimal zener current for maximum efficiency.

Introduction

The cell phone is one of the coolest, most useful, and convenient electronic devices of all time. It also happens to be one of the most complex technically, not only internally but also because it is part of the largest communications network in the universe, the telephone system. The reason for a separate chapter on this topic is not only because of the advanced wireless technology involved, but also its importance to all of us personally and to the national economy. Since practically everyone has a cell phone today, it plays a huge role in our lives. And for you techies out there, it is worthwhile knowing a bit of the details of how phone calls work, how text messages get sent, and how you can now access the Internet via your cell phone.

Cell-phones

The cell-phone network comprises a collection of individual networks all linked together. Public or private companies also known as carriers operate the transmitters, switches and connection to the PSTN and other networks. Many hand-held cell-phones have built-in serial interfaces, and are able to be used like standard data modem. The interfaces use the common Hayes AT command set. This is enhanced by the addition of specific commands for cell-phone communications, such as sending short message system (SMS) messages. All enhanced messages start with the character string ‘AT + C’. A number of these commands have recently been adopted by the mobile phone industry as ‘standard’ and are defined in GSM07.07 and GSM07.05 of the GSM specifications (control of mobile phones over a serial interface). The physical interface nominally uses RS-232 signal levels, but may also accept TTL levels (some cell-phones can also use infrared links). There are about 55 extra AT type commands in all. Extra facilities include access to some of the phone's internal facilities, phone books, fast call, SMS messaging, changing ring tones and speaker volume. A cell-phone with a RS-232 link effectively allows the remote terminal or PC take over control of the phone for all data aspects, no need to use the phone's keypad. In addition to the standard AT commands, some manufactures have defined extra commands. The Siemens 35 serials, for example, uses the prefix ‘AT^S’ to precede their vendor-specific set of commands.

Part XXVI Acoustical transducers for cellphones

The number of cellphones in the world is approaching 6 billion. These range from those that provide simple telephone services to those that serve as full business and entertainment centers. For all these, acoustical design is very important, but such design is involved because of limitations of space, ergonomics, and frequently the requirement of producing good-sounding music.

Shown in Fig. 8.1 is a cellphone with the characteristics of an entertainment center. The three main electroacoustic elements are the handsfree loudspeaker, the call loudspeaker and the microphone. The basic principles for the loudspeakers are the same as that for a loudspeaker in a closed baffle as presented in Chapter 7.

4.1.1 Driving style recognition by vehicle sensor data

During the last decade, auto insurance companies have started placing cameras in vehicles to lower insurance rates, and they have also observed that people drive better when being monitored. In addition, this also can assess performance of drivers during training sessions. In brief, understanding and recognizing driving events that fall into two categories, nonaggressive and aggressive, can aid in vehicle safety systems. In particular, drivers are usually unaware that they commit potentially aggressive actions daily.

Several companies offer products for fleet management and individual use in order to monitor driving behavior using expensive cameras and equipment. Fortunately, in recent years, IoT technologies have promoted research for driver safety and assistance systems, such as sensors available in smartphones. Johnson and Trivedi [13] proposed a system named a mobile-sensor-platform for intelligent recognition of aggressive driving (MIROAD) that is inexpensive, effective, and intelligently uses the sensors available on a cell phone. They fused related interaxial data from multiple sensors into a single classifier based on the dynamic time warping (DTW) algorithm [14], which was designed to find an optimal alignment of two signal vectors. In the MIROAD system, DTW aligned the currently detected event signal with the prerecorded template signals.

The latest cell phones are equipped with many useful inputs for research, including but not limited to:

camera (often multiple);

microphone (often multiple);

3-axis accelerometer;

3-axis gyroscope;

proximity;

ambient light;

touch;

magnetometer; and

GPS.

The MIROAD system focuses on the rear-facing camera, accelerometer, gyroscope (sampled at 25 Hz), and GPS (sampled at 1 Hz), but GPS is not always available. The types of events detected by MIROAD are:

right turns (90 degree);

left turns (90 degree);

U-turns (180 degree);

aggressive right turns (90 degree);

aggressive left turns (90 degree);

aggressive U-turns (180 degree);

aggressive acceleration;

aggressive braking;

swerve right (aggressive lane change);

swerve left (aggressive lane change);

device removal; and

excessive speed.

When trying to determine whether or not a driving event is typical (nonaggressive) or aggressive, the DTW algorithm finds the closest match between the different styles of templates. The aggressive templates consisted of high-jerk movements and turns that caused loss of traction.

With regard to device implementation, when the MIROAD application is started, it can be in one of two modes: active or passive. In the active mode, MIROAD monitors driving events and does not keep record of any sensor or video data unless a potentially aggressive event is detected. In the passive mode, the system records and stores all data for further analysis. The data consists of video and an archive of the raw device motion (acceleration, rotation, attitude, time stamps) with GPS data (longitude, latitude, speed, altitude, timestamps). The data is broken up into 5 min segment, just as in the active mode.