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10.4 Environmental Information and Navigation Technologies

Successful navigation of both the exterior and interior built environments is largely dependent on good quality signage, which should provide a combination of audio, tactile and visual information. This section considers audio signage, with Section 10.4.1 presenting an overview whilst Section 10.4.2 provides a description of some specific technologies.

10.4.1 Audio Information System: General Issues

Categorisation of audio signs

There are a number of different ways to categorise audio signs, including the following:

•The sensory modalities used to transmit the information; these include:

1.Single delivery modality, that is, solely audio information.

2.Dual delivery modality, that is, audio with visual or more rarely tactile information.

3.Triple delivery modality, that is, audio with both visual and tactile information.

•The type of technology used to transmit the environment information. Currently there are systems that use Bluetooth, wireless local area networks (LANs), infrared and visible light.

Technological aspects

The following principles of good design are common to all audio sign systems independently of the technology used.

Easy location of the sign or notice from a distance The two main options are illustrated in Figure 10.8 and given as:

1.Signs that are constructed as a sound beacon transmitting an audio signal to guide the traveller to its location.

2.Signs that transmit a continuous signal that can be intercepted by a handset. The transmitting medium may increase in strength as the user approaches the sign. An example is the Talking Signs technology based on infrared technology.

Sign activation There are three main cases, depending on whether the sign transmits continuously or requires to be activated and how it is activated. These three cases are illustrated in Figure 10.9 and listed as:

1.Activation by pressing a button located on the sign. This means that the user needs to be sufficiently close to the system to press the button and listen to the message transmitted.

Figure 10.8a,b. Finding an active sign or notice in the environment

Figure 10.9a–c. Methods for accessing information in an audio sign or notice system

2.The use of a handset to activate the sign, which then delivers its audio message to the user from a speaker embedded in the sign. The user needs to be sufficiently close to the system to activate the sign and listen to the information message transmitted.

3.The use of a handset to intercept the continuously transmitted signal from the sign. The handset then delivers the message to the user. This means the user could be some distance from the sign and still receive the information content

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of the sign. The handset could have a small embedded speaker or an earphone jack plug socket to deliver the audio signal.

Sound reception The audio message is heard by the user either on a earphone connected to the handset, or on a speaker, which could be located on either the handset or the sign. The use of a single earphone is generally preferable, as it reduces the impact of interference from environmental background noise and prevents disturbance to other pedestrians. As audio signs become increasingly widespread, avoiding disturbance to other pedestrians is going to become more important. The use of a single earphone also allows the user to access other audio environmental information.

Standardisation There are clear benefits to users in technological standardisation to allow all the different types of audio signs to be received by one handset, which would then process and convert the signal to transmit it to the user in audio or tactile form.

Coherent design of audio signage Currently audio sign systems are sparsely distributed and therefore tend to be installed on a local basis. There is a need for a more systematic approach involving national systems which can then be combined into a global system. This should include consideration of avoiding interference between different audio signs and the complementarity of audio signs and orientation systems, for instance based on global positioning systems.

10.4.2 Some Technologies for Environmental Information Systems

A number of different technologies can be used to transmit information from beacons that are embedded in the physical environment. In order to perform satisfactorily transmission technologies should have a number of properties, including the following:

•An adequate transmission range for the application.

•Non-invasive and/or imperceptible transmission to avoid disturbing other people.

•Avoidance of injury to people, animals and the environment.

•Mature and well understood technology.

•The easy availability of inexpensive system components.

Ultrasonic technology is generally not used in audio signs and therefore the different transmission technologies are based on particular frequency ranges of the electromagnetic spectrum. Table 10.4 shows typical properties and the frequency and wavelength ranges for the four main communications media used.

A detailed description of a public transport information system that uses Bluetooth and mobile telephone technology is presented in Chapter 11. Systems that use infrared and visible light transmission technologies are described in this section.

10.4.2.1 Infrared-based Environmental Information System

There are several commercially available systems that use infrared technology to create a beacon system to provide information messages to a user’s handset. These systems include Talking Signs®, Infravoice, and the Easy Walker system. The Talking Signs system has been installed in a number of different types of locations in several different countries. The discussion of the Talking Signs system in this section is used to illustrate the operational principles of infrared-based systems and their potential flexibility.

Talking Signs

Talking Signs provides a repeating, directionally selective voice message, which originates at the sign and is transmitted by infrared light to a hand-held receiver some distance away. The directional selectivity is a characteristic of the infrared message beam where the intensity and the clarity of the message increases as the sign is pointed at or approached. This ensures that person using the Talking Signs system can obtain feedback about their relative location to their goal as they move towards it. Talking Signs are light and small, easy to install, consume very low power, and are easy to program with human voice or synthesised speech messages. Figure 10.10 shows a Talking Signs system in action. The user is pointing a receiver handset at a wall-mounted beacon to obtain information about the stairway.

The infrared system uses light-emitting diodes to transmit digitally encoded speech messages that are intercepted by a hand-held receiver and then a speaker in the receiver unit relays the message to the user. Each infrared transmitter consists of a rectangular plastic box containing the message unit, transmitter driver electronics and three LEDs. The pre-recorded human speech frequency message modulates a 25 kHz infrared carrier signal. As the infrared beam carrying the speech message is transmitted, it spreads out as a cone from the infrared diode, becoming wider as the beam moves away from the source. Tuning the transmitters and the LED arrays allows control of the maximum distance at which the Talking Signs message is received, the direction of transmission, and the area

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Figure 10.10. Talking Signs® in action (photograph reproduced by kind permission of Talking Signs Inc. USA)

Figure 10.11. Cone of infrared transmission signal

the message covers, as illustrated in Figure 10.11. Because different signs have different functions, the range and dispersion angles of each sign are adjustable.

The hand-held receiver consists of a box containing a frequency modulated (FM) discriminator, an amplifier, an internal speaker and a photo-detector at its front end. The message is detected when the receiver is pointed in the direction of the sign transmitter. A digitally recorded message is heard whenever the sensor aperture on the front of the receiver is pointed in the direction of the infrared transmitter while the receiver is activated. Thus, Talking Signs are a directional system whose messages are received only when the user activates the receiver. Therefore, system users do not receive unwanted information. However, other pedestrians in the vicinity of the user may hear the message, making the use of a single headphone preferable. This would also prevent the information disappearing in environmental noise. The handset has an on/off switch, a volume control and a jack port for headset use. It is powered by a 9-V battery and can be carried on a cord around the neck to free the hands for other tasks. Figure 10.12 shows a Talking Signs transmitter beacon and a handset with internal speaker.

This type of beacon and information access technology has a number of potential and actual applications, including the following:

1.Way-finding and information systems for interior and exterior environments. Exterior environments include shopping centres, railway and bus stations, whereas interior environments include hotels, hospitals and government of-

Figure 10.12a,b. Talking Signs® beacon and handset receiver (photograph reproduced by kind permission of Talking Signs Inc. USA)

fices. A centralised system would typically be based on groups of ten transmitters powered through a centralised control unit. Stand-alone units could be used in locations that are not easily linked to a centralised system and for one-off applications. These single units would have a dedicated transformer to provide 12-V power, a recorded card and dedicated transmitting head.

2.Personal way-finding systems, comprising a transmitter with messages recorded by the user and a personal receiving handset. This could be used by individuals to mark and locate personal destinations, such as a hotel room door, a train seat or a restaurant table.

3.The Talking Signs® technology has been incorporated into the electronic destination panels of buses. This enables the receiver handset to be used to identify individual bus services from a distance of around 30 m, thus facilitating independent bus travel. Figure 10.13 illustrates such a bus identifying system.

4.A modified Talking Signs system has been used in pedestrian crossing systems to provide commands for safe crossing and additional information about crossing locations and traffic conditions.

Users would benefit from standardisation to allow the same handset to be used with all beacon and information access applications. Other pedestrians, particularly noise-sensitive ones, would benefit from the internal speakers being replaced by a headphone, especially as Talking Signs and analogous systems become more widespread. It should also be noted that the combination of a small hand-held