MXPA97000857A - Alert device and system for situationsanorma - Google Patents

Abstract

The present invention relates to a system for broadcasting an emergency warning through an area around a site, the system comprising: a source at the site of an audible or visual warning signal detectable by at least one of the human senses; an on-site transmitter for broadcasting an electromagnetic warning signal within a tunable bandwidth of a standard radio receiver to receive commercial broadcasts, with at least part of the electromagnetic deadverted signal encoded in an RDS-compatible format; of the transmitter whose power ratio provides an effective range of the electromagnetic warning signal that complements an effective range of the audible or visual signal and is approximately coextensive with it, and means for detecting the electromagnetic warning signal within its effective range and in response to it by tuning the receiver to ia a carrier frequency of the electromagnetic warning signal

Description

ALERT DEVICE AND SYSTEM FOR ABNORMAL SITUATIONS FIELD OF THE INVENTION This invention relates to emergency warning systems and devices, and more particularly, to such systems that inuence a visual or audible warning device. BACKGROUND OF THE INVENTION Various products have been developed to alert the general public about the presence of abnormal situations, which sometimes require action to protect life and property. These products include applications in a local area and in a wide area. In local area products, the work of alerting is usually carried out by a visual and / or audible signal such as flashing or rotating lights and sirens. Local area products are most commonly used with emergency vehicles. Such systems try to take care of the public in the proximity of vehicles. Wide-area products are exemplified by the United States Emergency Broadcast System, which uses wide-area RF transmitters to communicate emergency signals over a large geographic area. In general, alert products broadcast radio frequency (RF), audio or light signals. The light and audio signals are attenuated relatively quickly as they propagate in relation to the RF signals. This property makes alert products, which broadcast particularly appropriate light and / or audio signals to alert only over a range of several hundred yards from the site where the broadcast originates - that is, a local area. Also, the light and audio signals are directly detectable by the human senses. On the other hand, RF signals are less attenuated by the atmosphere than light and audio signals and, therefore, are effective in providing warning signals over a wide range of several thousand or more, depending on the power of the signals. Signals on the broadcast site - that is, a wide area. In addition, RF signals pass through most building materials without substantial attenuation, making them particularly suitable for driving warning signals into a home or into other environments that isolate occupants from environmental conditions. Although the range of RF signals is much more dynamic than light and audio signals, RF signals have the distinct disadvantage of requiring a receiver of signals in order to possess a device to convert RF signals into signals that can detect one or more of the five senses of the receiver. Typical diffusion area-based RF warning systems have used conventional AM / FM receivers in the past as the device for converting the RF signal. In these systems, a commercial broadcaster agrees to use its transmitter as part of a community warning system. The transmitters used by these commercial diffusers are typically high power, immobile devices. In the United States, a national emergency network of this type is the Emergency Dissemination System. The network consists of a number of wide area diffusers proposed to cover the United States with an emergency RF signal that can be received by conventional receivers. These emergency broadcasts use commercial-based dissemination systems that lack flexibility and that attempt to provide global coverage over large geographic areas. Traditional warning products that broadcast audible and / or visual broadcast warning signals are well suited for a local application area. However, they have diminished their effectiveness when those who try to receive their signals are located in an isolated environment or an obstructed environment with other audible or visual "signals" - for example, urban areas. For example, flashing lights are only visible within a direct line of sight and can not be seen around the corners of buildings, which is particularly a problem in urban areas. Likewise, warning sirens can not be heard by individuals with reduced or uneven hearing or in noisy vehicles, urban streets or well-insulated homes. Other factors that reduce the effectiveness of local warning systems include the use of audio systems in a vehicle, heavy traffic conditions, climatic conditions that force the windows to rise and the noise of forced air systems. Also, vehicles and homes have recently been better isolated, further improving the masking of audible or visual warning signals. These signal masking problems increase the likelihood that an audible or visual warning device will not be notified in a vehicle or construction. In addition, although local area warning devices are used by almost all emergency vehicles, such vehicles themselves often suffer from reduced knowledge of other emergency situations. For example, a fire truck traveling in an emergency mode typically generates audible and visual signals to warn the motoring public and pedestrians that the truck is operating outside the normal mode of traffic circulation (eg, high speed and opposite speed). to the signal and lane flow controls). When two or more vehicles respond to an emergency from different points of origin, they typically approach the emergency along different routes, thus becoming a risk to each other. In addition to the increased risk due to travel in abnormal modes, the warning siren or emergency warning lights of a first vehicle tend to mask the ability to perceive the warning lights or sirens of other emergency vehicles. Various purposes have been made to overcome these problems of traditional warning devices. The various purposes have employed equipment dedicated to the transmission of local area warning signals through RF transmission links. For example, known systems have used a dedicated transmitter located in an emergency vehicle and, similarly, dedicated receivers in vehicles or places to be warned. These systems require the installation and maintenance of RF receivers in addition to conventional RF receivers of commercial bandwidths, usually found in the vehicle or in the home, and, consequently, these systems have failed to gain acceptance in the market. Part of the lack of diffusion breadth used by such products refers to the poor perceived cost-benefit ratio for dedicated receivers that take up substantial space (especially in a vehicle) and are rarely used. In addition, when operating, the user can see the conventional audible and visual warnings as effective on their own and, therefore, conclude that the dedicated receiver provides only an increase and an unnecessary improvement. Another problem with the known local area warning systems employing RF links is the practical difficulty related to the installation of additional emergency radio equipment in a vehicle. Increasingly, the assembly problems with the decrease in the size of the compartments of the passenger vehicle coupled with the limitations on the mounting locations of such additional equipment due to interference with the deployment of an airbag and the like, arrive. SUMMARY OF THE INVENTION The basic objective of the present invention is to provide the improved warning capability of the local area systems of the prior art that employ RF links without requiring dedicated receivers.

It is also a basic object of the invention to incorporate in the local area warning system conventional electronic devices available virtually in all homes and vehicles to receive warning signals that complement audible and visual, local or community warning signals. A related object of the invention is to complement an external audible warning signal with an additional signal that can penetrate the relatively isolated environment of a typical home or modern vehicle. Still another object of the invention is to provide the above and other objects through an improved warning system that alerts an individual to the presence of an emergency vehicle in the environmental area close to the vehicle or other abnormal situations, even when the The individual is located in an environment that is somewhat isolated or masked from the audible and visual signals broadcast by the vehicle. Briefly, the invention comprises a transmitter for radiating a local warning signal from a mobile site such as an emergency vehicle or from a fixed location such as a siren mounted on a tower, where the warning signal is transmitted on a carrier frequency F0 within a tunable bandwidth of a standard radio receiver to receive commercial broadcasts and includes control signals in a sideband encoded in a compatible format of Radio Data System (RDS). Because the warning signal attempts to provide a local warning that complements traditional visual and audible warning signals, the transmit power amplifier has a power irradiation to provide a transmission area whose effective range is approximately coextensive with the range of the visual and audible signals in ideal conditions. When used with an emergency vehicle, the transmitter is preferably compared to a transceiver that provides a communication link between the emergency vehicles within an area approximately equal to the area covered by the signals of the transmitter. The transceiver operates within a bandwidth different from the bandwidth of the transmitter. For example, the transmitter preferably broadcasts within the tunable range of a standard FM receiver, as long as the transceiver can be broadcast within a bandwidth assigned to the police and other community services. When used at a fixed site, the transmitter is typically used alone. However, manipulation of the transmitter is normally carried out in conjunction with a visual or audible warning signal of a conventional type. For example, most communities have a network of sirens strategically located throughout the population in order to ensure that the warning signal collectively provided by the sirens reaches everyone. In each siren or in a siren in the approximate center of a group of sirens that are controlled in a common way, a transmitter according to the invention is manipulated with the activation of the siren or group of sirens. Preferably, in any of the above embodiments, the warning signal is selected to be a carrier frequency F0 at the high or low end of the tunable range of a commercial FM bandwidth - i.e., 87.5 MHz to 108.0 MHz at the United States. An audible warning signal is conducted on the carrier frequency F0 (ie, siren, tone or voice) and the control signals are conducted on a frequency of the sideband (SB) of the frequency. carrier The control signals are encoded in the RDS format for decoding by the receiver. The reception of the control signals encoded by RDS through a receiver causes the receiver to respond to the decoded commands coming from the control signals, which typically results in re-tuning the receiver to the carrier frequency F0 to demodulate the warning signals and supply the warning signal to the speakers connected to the receiver. In order to secure the receiver functions in a normal mode while at the same time maintaining an ability to recognize the control data on the SB frequency, the receiver includes two front ends. A front end is controlled by the user to select a desired commercial FM broadcast in a conventional manner of operating an FM receiver. A second front end already scans the tuned FM bandwidth by looking for the control signals over any SB frequency or is tuned to the selected emergency vehicle F0 and continuously monitors its SB frequency for the control signals. In any architecture for the front end, the reception of a control signal by the second front end causes the receiver to switch its amplification circuitry to the second front end and broadcast the warning signal carried over the frequency F0. In this way, for example, the receiver can play music or the like in conventional mode, which could create or improve the isolation of the environment. After reception of the control signals from the emergency vehicle, the receiver switches from its conventional mode of operation to an emergency mode, providing an audible and / or visual indication that alerts the user of the receiver about the presence of a situation emergency when the user is in an area near the transmitter. When used in an emergency vehicle, both the transmitter and the transceiver may include an automatic gain control (AGC) that responds to the speed of the emergency vehicle in order to control the range of signals transmitted in relation to the speed of the vehicle. vehicle. In addition, a further improvement includes the configuration of the radiation pattern of read emergency signal broadcast by the transmitter and transceiver to direct the signals in the most appropriate manner for the situation. For example, if the vehicle is parked, the radiation pattern can be configured to form two complementary lobes, one directed forward and the other backward of the vehicle. Such a pattern better warns oncoming traffic without unnecessarily alerting surrounding villagers or remote cross streets. Finally, the transceiver on board the emergency vehicle may include information that describes the. State of the vehicle to be used by a receiver emergency vehicle. For example, sensors on board the emergency vehicle can provide information regarding the speed, direction and instantaneous position of the vehicle. In the transceiver on the receiving emergency vehicle, this information can be decoded to provide a visual display of the. position, direction and speed of the transmitting vehicle. For example, the display can be a simple vector arrow whose position, orientation and length on the screen are determined by the position, direction and speed data, respectively. Although the invention will be described in some detail with reference to the preferred and alternative embodiments, it will be understood that no attempt is made to limit the invention to such detail. On the contrary, attempts are made to cover all alternatives, modifications and equivalents that fall within the spirit and scope of the invention as defined by the appended claims. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a simplified block diagram of an Emergency Vehicular System (EVS) according to an embodiment of the present invention, wherein the RF communication links are established between two emergency vehicles towards a conventional FM receiver; Figure 2A is a schematic illustration of the tunable bandwidth of the conventional FM receiver of Figure 1, which includes within the bandwidth an approved region for commercial broadcasts and a region at either end of the bandwidth to broadcast emergency signals according to the invention; Figure 2B is a schematic illustration of two radiation patterns by alternative antenna configurations, where the first configuration (i) provides a substantially omnidirectional pattern and the second configuration (ii) provides an elongated pattern, - Figures 3A to 3E are diagrams graphs illustrating various applications of the invention, in which Figure 3A is an illustration of an application of the invention wherein both the transceiver and the transmitter of Figure 1 are mounted on an emergency vehicle for disseminating information and warning signs both emergency vehicles and "civilian" vehicles, Figure 3B is an illustration of an application of the invention wherein only the transceiver of Figure 1 is mounted on an emergency vehicle to broadcast information and warning signals to other transceivers similar, which are typically mounted on other emergency vehicles, the ra 3C is an illustration of an application of the invention wherein only the transmitter of figure 1 is mounted on an emergency vehicle for broadcasting information and warning signals to conventional FM receivers in "civilian" vehicles, Figure 3D is a illustration of the invention wherein only the transmitter of figure 1 is associated with one of several exemplary static warning systems and is configured to complement the conventional visual and audible warnings employed by the static system, and figure 3E is an illustration of a application of the invention in a school bus, wherein the transmitter of figure 1 is manipulated by the. unfolding of a HIGH signal on the side of the. bus; Figure 4 is a schematic diagram of an RF system on board the emergency vehicles of Figure 1, which graphically illustrates an exemplary control panel for the transceiver and transmitter of the system plus several sensor inputs whose data are indicative of a vehicular state; Figure 5 is a more detailed schematic diagram of the RF system of Figures 1 and 4, illustrating further details of the transceiver, transmitter and control head of the RF system; Figure 6 is a diagram illustrating the preferred coding structure for the broadcasting of control data on a sideband of a carrier frequency F0 to which the transmitter of Figure 1 is tuned; Figure 7 is a logical flow diagram for the operation of the transmitter and the transceiver of the RF on one of the emergency vehicles shown in figure 1; Figure 8 illustrates a block diagram of a receiver for receiving commercial AM and FM broadcasts as well as the carrier frequency F0 transmitted by the. transmitter in Figure 1 and the control data of Figure 6, the latter being transmitted by the transmitter on a sideband of the carrier frequency; Figure 9 is a logical flow diagram illustrating the operation of the receiving section of the figure 8; and Figure 10 is a schematic illustration of a control panel and a display screen for the receiver of Figure 8.

DETAILED DESCRIPTION OF THE PREFERRED MODALITIES In one embodiment of the invention illustrated in Figure 1, an alert system 11 of the present invention is proposed to be used in conjunction with conventional siren and light devices of emergency vehicles A and B (for example, police vehicles, firemen or ambulances). In an alternative mode, the warning system can be used with static devices such as road signs or external warning sirens, as described in more detail hereafter. In a further alternative embodiment, the invention contemplates applications with. non-emergency vehicles such as school buses. A particular aspect of the modality of the. FIG. 1 is the transmission and reception of emergency data between emergency vehicles A and B on an Fx frequency and the transmission of emergency, complementary data from emergency vehicles A and B to receiver 17 on a frequency F0, the latter providing public monitoring (or that in fixed places) with a warning of potential emergency situations. In this way, motorists in the immediate area or those in fixed locations can receive warning information from emergency vehicles. According to one embodiment of the invention, the alert system 11 includes a transceiver 13 located on a first emergency vehicle A for supplying RF signals at a first frequency F? to one or more different B emergency vehicles also equipped with a similar 13 'transceiver to minimize the risk of decoliation in emergency situations. According to another aspect of the invention, the alert system also includes a transmitter 15 for transmitting a de-emergency RF signal to a second frequency F0 towards a conventional receiver 17 that receives RF signals transmitted over commercial bandwidths during its normal operation. Preferably, a sideband (SB) of this second RF signal uses the Standard American Radio Broadcast Data System (RBDS) produced by the National Radio Systems Committee guaranteed by the Electronics Industry Association (EIA) and the National Association of Diffusers (NAB). The receiver 17 is compatible with the RBDS standard for the purpose of changing the mode of operation of the receiver to an emergency mode when it receives the sideband. The details of this Standard and its implementation are established in the. Specification of Radio Broadcast Data Systems published by the EIA and NAB in 1992 and entitled "RBDS Standard of the United States, January 8, 1993". This specification is incorporated herein by reference. Of course, for use outside the United States, the standard is appropriate to the country in which the system being used is to be used - for example, the European Radio Data System (RDS) standard established by the European Union. of Dissemination. An example of such a receiver compatible with the RBDS, which has a single front end, is the Denon Model No. DCT-950R, which is available from Denon Corporation of 222 New Road, Parsippany, New Jersey 07054. In general, the RBDS it provides digital-encoded transmission of information in a side band of unei carrier frequencies for a normal FM (or AM) voice and music channel. Depending on the specific hardware and software of the receiver 17 as discussed hereafter, the digital information is decoded and either displayed on a display screen of the receiver 17 or interpreted as command signals to control the operation of the receiver. Control signals transmitted in the sideband can, for example, turn on the receiver 17 and / or tune it to other frequencies (for complementary weather or traffic information). In Figure 10 a front panel of an exemplary RBDS receiver 17 is shown. From its outward appearance, the receiver 17 differs from the conventional commercial RF receivers basically in its larger alphanumeric display 332 and in the control buttons of RBDS 38. In order to transmit information according to the RBDS Standard, the information digital appears on the third harmonic (a sub-vehicle) of the "pilot tone" of 19 KHz for stereo broadcasts in the FM band between 87.5 and 108.0 MHz. (During monophonic broadcast the frequency of the coded sub-vehicle is 57 KHz). The digital information is encoded in this sub-vehicle as a signal of modulated amplitude and is configured by data signals encoded by biphase, using the differential coding scheme that follows a protocol outlined in the RBDS Standard. The power of the data signal in and near the sub-vehicle is minimized by coding each bit of source data as a biphase signal. There is a dual binary signal configuration filter (not shown) for configuring the spectrum that limits the band and the synchronization and frequency spectra of the radio data signals encoded by biphase. The result of this frequency coding at the transmitter 15 and the subsequent frequency decoding at the receiver 17 is a stream of coded binary data as shown in Fig. 6. The data stream is formatted into groups, where each group of data It comprises 104 data bits. The 104 bits of data in each group are divided into four words of 26 bits each. The first 16 bits of each word are the information word and the last 10 bits are the verification bits for the word. Generally, blocks 3 and 4 are used to send information to receiver 17 to be deployed, while Blocks 1 and 2 are normally set apart to provide command or control information for control of the receiver. For example, Blocks 1 and 2 may include a Program Service Code (PS code). The PS code informs the receiver 17 that Block 3 contains the call documents of the transmission station, which must be displayed on the display screen 332. In addition, to display the call documents, the RBDS standard also provides the display screen 332 that shows the programming format of the station - for example, jazz, rock, classical, etc. The programming format is identified by a Program Type code (PTY) that has up to 31 categories. Categories 30 and 31 of the code are reserved in the RBDS Standard to display "proof" (No.30) and "alert" (No. 31) on the alphanumeric character display screen 332 of receiver 17 (see figure 10) . It is intended that this invention use category 31 of the PTY code as part of its characteristics as explained more fully hereinafter. Returning to the schematic illustration in Figure 1, each of the two emergency vehicles A and B is equipped with the warning system 11 according to one embodiment of the invention. The following is a description of the warning system 11 of this first embodiment with reference to the emergency vehicle A and the operation of that system with the complementary warning system mounted on the emergency vehicle B. The person skilled in the art will appreciate that although the The following discussion is with reference to the warning system 11 mounted on the emergency vehicle A, it is equally applicable to the warning system mounted on the emergency vehicle B. Furthermore, one skilled in the art will appreciate that any number of emergency vehicles equipped with the warning system 11 can cooperate to provide emergency warning according to the invention. Similar devices in emergency vehicles A and B are identified by the same number. However, in order to distinguish between the two systems, the numbers that identify the warning system and its components of the vehicle B are cousins - that is, 11 ', 13', 15 ', etc. The transceiver 13 of the warning system 11 transmits information by radio and receives radio information from the warning system 11 'mounted on the emergency vehicle B through the antennas 19a and 19b. In the illustrated embodiment, the transceiver 13 transmits over a frequency Fx within the bandwidth allocated for emergency use - for example, the bandwidth of the police. According to the invention, the effective range of the antennas 19a and 19b and the sensitivity of the receiving portion of the transceiver 13 'in the warning system 11' of the emergency vehicle B are complemented with one another so that the system of emergency vehicle alert B detect the RF signal transmitted from the emergency vehicle warning system A when two vehicles are within a predetermined distance from each other - for example500 yards. In this way, transceiver 13 or 13 'of emergency vehicle A or B, respectively, transmits signals on the proposed frequency Fa to alert other emergency vehicles of their presence in the vicinity of those other emergency vehicles, thereby reducing the risk of a collision. In this regard, transceiver 13 provides only local area coverage.

Referring to Figure 2B, a single dipole antenna Al provides a substantially omnidirectional diffusion pattern (i). An on-directional pattern of the RF warning signal from transceiver 13 may be most appropriate in open areas or intersections in urban areas. By exciting two antennas Al and A2 spatially separated by an appropriate distance as illustrated in Figure 2B, an elongated pattern (ii) is provided for the radiation of; RF signal. This pattern may be the most appropriate for transceiver 13 in divided road situations in order to alert only vehicles on one side of; the highway. Through the use of conventional techniques, the warning signals transmitted by the transceivers 13 and 13 'can be analog or digital signals decoded by the receiving transceiver as audible or visual information. Simultaneous transmission by multiple vehicles within the range of others can be carried out by employing either the same Fx frequency or multiple frequency transmission protocols. Various techniques are known for simultaneous transmission over different frequencies. The techniques for transmitting the same Fx frequency by the use of different time-sharing protocol schemes are also well known. Poi: example, in a technique to transmit on different frequencies, the frequencies are selected to compare the frequencies in which a scanning receiver expects the information to be located. An example of the same frequency technique is the use of packet radio technology as known to those skilled in the art. Other examples of the same frequency protocols are a time domain multiple access (TDMA) technique and a code domain multiple access (CDMA) technique, both of which are known in the art of modulation and RF transmission. . Other known techniques or protocols may also be suitable for emergency vehicle-to-emergency vehicle transmission according to the invention. Additional details of the previous techniques and protocols and possible additional alternatives can be found in the following references: Telecommunication Enaineerina. 2nd Ed. By J. Dunlop and D. G. Smith, Van Nostrin, 1987, ISBN 0-278-00082-7; ireless Communication Handbook, Ed. by Gary Breed, 1992, Cardiff Publishing Co. (No ISBN Number), - and Telecommunication Transmission Systems, McGraw-Hill, 1993, by Robert G. Winch, ISBN 0.07-070964-5. Returning to the operation of the transmitter 15, it broadcasts a carrier frequency F0 over a local area - for example, a range of 100 to 500 yards. A sideband of the carrier frequency F0 includes coded information using the RBDS Standard and specifically the category 31 of the PTY code, which is used in the invention to place the receiver 17 in an emergency mode. In a conventional manner, the carrier frequency F0 is frequency modulated with an audio alarm or alert signal (eg, voice or siren). As will be appreciated by one skilled in the art of radio transmission and reception, the transmitter 15 can alternatively transmit a modulated amplitude (AM) signal, with one of the sidebands of a carrier frequency of AM F0 'containing information digitally encoded using the RBDS Standard. Through the use of conventional techniques, the carrier frequency F0 'is amplitude modulated by an audio signal to alert a receiver 17 in the range of the transmitter 15. According to the invention the frequency F0 or F0' is within the range tunable of the conventional receiver of FM or AM commercial broadcasts, respectively. As illustrated in Figure 2A, a bandwidth approved in the United States by the Federal Communications Commission for commercial broadcasts of FM and AM is less than the tunable range of conventional receiver 17. Preferably, the frequency F0 (FM) or F0 '(AM) is dedicated to the function of broadcasting signals and emergency information and, therefore, is outside the commercial bandwidth but within the tunable range of the receiver 17. As illustrated in Figure 2A, the frequency of F0 or F0 'may be either adjacent to the upper or lower end of the commercial bandwidth. Alternatively, the frequency F0 or F0 'could be located within the tunable bandwidth if the frequency space is available. However, this approach would be more likely to require that the frequency F0 or F0 'have different values in different geographical regions since not only a frequency within the bandwidth would necessarily be available in all geographical areas. The use of different values for frequency F0 or F0 'does not present a design problem for receiver 17 since one of its front ends (discussed hereafter) may be scanning all tuneable frequencies for control information about a side band. However, unfortunately, the use of this alternative approach avoids the manufacture of the transmitter 15 tuned to a single frequency value of F0 or F0 '. Accordingly, the frequency F0 or F0 'is preferably an out-of-band frequency whose value is fixed to all geographical areas. Preferably, the transmitter 15 operates on the F0 frequency of 87.5 (or 108.5) MHz located at the lower (or higher) ends of the FM broadcast range. According to the invention, the category 31 of the PTY code (ie, the alert code) of the RBDS Standard is transmitted by the transmitter 15 to turn on and / or raise the volume of the receiver 17. As an alternative to the category 31, a new category of the PTY code could be defined in the range of categories 23-29, whose categories it has reserved as the Standard currently reserves. In addition to the turning on of the receiver 17 (if it is off) and the volume adjustment, the alert code PTY is also switched from the receiver 17 of the commercial station to which it is tuned to the frequency of the fixed emergency vehicle F0. Alternatively, if the receiver 17 does not have the ability to perform this re-tuning function in response to the appropriate PTY code, an RBDS Traffic Announcement Identification (TA) code is transmitted and used to order the receiver 17 switch to frequency F0. In still another mode of the receiver 17, the volume of the audio signal carried by the FM station that is currently being heard is reduced and mixed with the emergency audio signal after reception of the TA code. In this mode, an emergency signal carried over the frequency F0 is heard as a traffic announcement with the audio coming from the FM station to which the user is tuned in the above. When the transmitter 15 is manipulated, the broadcast signal is preferably transmitted with a range that complements the range of the audio and / or visual warning system to which the transmitter is associated. In addition, the range of the warning signal may vary to accommodate various conditions. For example, in a vehicular application as illustrated in Figure 1, the power of the transmitter 15 and therefore the range of the warning signal may vary with the speed of the vehicle as discussed hereinafter. In a specific mode, the range of the warning signal varies from a minimum of 500 feet from 0 to 15 MPH up to a maximum of 2500 feet when the emergency vehicle reaches a speed of 45 MPH and above. In the embodiment illustrated in Figure 1, the alert system 11 includes a conventional device for broadcasting audio / visual signals. A conventional siren 21 and emergency lights 23 are mounted to the vehicle A. A controller 25 also of conventional type provides command signals to the siren 21 and lights 23. A bidirectional line 27 connects the controller 25 to a control panel 29 that provides a user interface to control the lights 23 and the siren 21. An example of a suitable light device is a VISION warning system, prepared by Federal Signal Corporation of Univerity Park, Illinois. An example of a suitable siren is a SMART SIRENMR, manufactured by Federal. Signal Corporation of Univerity Park, Illinois. These examples include a suitable controller and control panel according to the illustrated embodiment. The VISION ™ warning system and SMART SIREN ™ are described in U.S. Patent Application No. 08 / 213,266 and U.S. Patent No. 5,296,840, respectively, which are incorporated herein by reference. In accordance with an important aspect of the invention as illustrated in Figure 1, a controller 31 provides command signals for manipulating the transceiver 13 and the transmitter 15 in response to signals from a control panel 33 via the line bidirectional 35 or in response to the signals from the controller 25 by means of a "remote" line 37. When the siren 21 and / or the lights 23 are activated, a signal is supplied to the controller 31 from the controller 25 by means of the "remote" input line 37. Depending on the mode of operation of the controller 31 as explained hereafter, the controller responds to the signal on its remote input line 37 by manipulating the transceiver 13 and the transmitter 15 to broadcast signals RF warning signals that complement the audio / visual signals of the siren 21 and the lights 23. When broadcasting the RF warning signals, either one or both antennas 19a and 19b are excited, depending on the the desired diffusion pattern for the transceiver 13. Likewise, either one or both antennas 20a and 20b are excited, depending on the desired diffusion pattern for the transmitter 15. The invention can be configured in several alternative modes, some of which they are illustrated in Figures 3A to 3D. In each of the embodiments in Figures 3A-3C, the alert system 11 of Figure 1 includes one or both of the transceiver 13 and the transmitter 15. For example, in Figure 3A, the alarm system 11 and 11 ' in each of the emergency vehicles A and B, respectively, includes both the transmitter 15 and the transceiver 13 as illustrated in figure 1. In this embodiment, each of the emergency vehicles A and B alerts both the other vehicle of emergency as to receiver 17 on the non-emergency vehicle C when they are within the range of transceiver 13 and transmitter 15.

In the embodiment illustrated in Figure 3B, the on-board system of each of the vehicles A and B includes only the transceiver 13. In this mode, each emergency vehicle A and B alerts only to other emergency vehicles equipped with an emergency vehicle. similar type of transceiver 13. In the embodiment of Figure 3C, the on-board system of the emergency vehicle A or B includes only the transmitter 15 for alerting the passenger vehicle C having the receivers 17. In this respect, although the illustration Figure 3C suggests that the passenger vehicle C is not an emergency vehicle, it will be appreciated by one skilled in the art that an emergency vehicle can also be equipped with the receiver 17 and, therefore, can also receive signal broadcasting of emergency by the transmitter 15. In addition, the receiver 17 placed in fixed places such as residential housing and the like can also receive the emergency signal if the transmitter 15 s It is in the range of the receiver. According to the invention, a further embodiment of the invention is illustrated in Figure 3D, which illustrates various fixed, visual or auditory alarm systems, which incorporate the transmitter 15 for purposes of providing a complementary RF signal to the receiver RDS-compatible 17 of figure 1. In these embodiments, an audio and / or visual alarm system according to the invention transmits from a fixed location. In accordance with the general architecture of the embodiment of Figure 1, the embodiments of Figure 3D include the controller 31 for manipulating the transmitter 15 in response to a remote activation signal from the audio and / or visual system it complements. In general, the architecture in Figure 3D provides the signal that activates the visual and / or audible signal to also manipulate or activate the transmitter 15, which is physically located close to the audio / visual system. An example of an audio / visual system that can be coupled with the transmitter 15 is a conventional railroad crossing system 41 as illustrated. Another example is a community warning siren 43 as illustrated. An example of an external warning siren that may employ the RF link of the invention is set forth in U.S. Patent No. 5,146,508, which is incorporated herein by reference. Yet another example is a school alarm system 45 as illustrated. The alarm system 45 includes a schedule system for synchronizing the school bells. The system 45 cooperates with the transmitter 15 to manipulate the transmitter during scheduled recesses and before and after school. Permanent road signs such as the signal 47 illustrated in Figure 3D can be coupled to the transmitter 15 according to the invention to continuously transmit an RBDS signal or to transmit the signal during selected periods of time in a daily, weekly or even monthly. Also, portable traffic control devices such as the arrow board 49 illustrated in Figure 3D can employ the transmitter 15, by manipulating the transmitter when the arrow board is operating. Of course, the alarm signal and the RBDS codes are adapted to each modality. In a variation of the embodiment illustrated in Figure 3C, the emergency vehicle A or B may instead be a school bus 51 or the like as illustrated in Figure 3E. Instead of the transmitter 15 being manipulated either manually or remotely as a result of the activation of the lights 23 and / or the siren 21 of the emergency vehicle, an embodiment of the invention applied to the school bus 51 automatically activates the transmitter 15 on board the bus in response to the mechanical pivot of a stop sign 53 articulated next to the bus in a well-known manner. The movement of the mechanical link 52 pivots the stop signal 53 from a position bent at the side of the bus 51 to a position extending from the bus to be visible to other vehicles. The extension of the stop signal 53 also manipulates the transmitter 15 to broadcast an RBDS signal that is decoded by the receiver 17 in an approaching vehicle., in order to warn the occupants of the vehicle that they are approaching the stopped school bus 51. In the illustrated embodiment, a sensor 54 detects the movement of the mechanical link 52 in order to provide a signal on the remote entry line 37 that causes the controller 31 to manipulate the transmitter 15. The sensor 54 may simply be a switch engaged to the mechanical link 52 to unfold the stop signal 53. Figure 4 illustrates a graphic diagram of a typical control panel 33 of the system of any vehicle of emergency A and B in Figure 1. The on-board system of the emergency vehicle includes the transceiver 13, the transmitter 15, the controller 31, and the antennas 19a, 19b and 20a, 20b. The control panel 33 includes an alphanumeric display 55 as well as various warning or indicator lamps as described below. Although the control panel 33 is preferably mounted in the driver's compartment in the emergency vehicle A or B to allow the driver to see the deployment screen 55, it can alternatively be mounted in a fixed location according to the embodiments of Figure 3D . Of course, in its simplest mode as suggested by Figure 3E, the system of the invention does not include the control panel 33 and the transmitter 15 and / or the transceiver 13 are manipulated only through an audio alarm system / visual, conventional, associated. In the embodiment of Figure 4, the controller 31 receives remote, automatic and manual input signals to manipulate the transceiver 13 and the transmitter 15. The remote input line 37 of Figure 4 is from the controller 25 of the audio system / visual 232 comprising the lights 23 and the siren 21, conventional. The controller 31 also receives input information regarding the operation state of the vehicle from the sensors 231 through automatic input lines 57-63. Depending on its programming, the controller 31 responds to these various inputs by manipulating one or both of the transceiver 13 or transmitter 15. For example, in the illustrated embodiment of Figure 4, the controller 31 receives an input signal from the parking switch / neutral 65 of the emergency vehicle through line 63, thereby providing the controller with an indication of whether the emergency vehicle is parked or is moving. According to its operation program as discussed more fully hereinafter, the controller 31 may change the message about the FB frequency of RBDS or change the broadcast pattern (see FIG. 2B) in response to a change in the state of the switch 65. The controller 31 also receives information describing the directional heading of the emergency vehicle coming from a radio-compass 67. This information is coded and transmitted to other emergency vehicles through the frequency Fx broadcast by the transceiver 13. it can also be supplied to the receiver 17 through an RBDS code on the sideband of the frequency F0. A change in the header of the vehicle is detected by the controller 31 and the data dissemination is updated by the transceiver 13. The speed of the emergency vehicle A is monitored by the controller 31 from a speed sensor 69 in order to vary the transmission power of the transceiver 13 and the transmitter 15 as explained hereafter in relation to figure 5. This velocity information is used to correlate the effective range of the transceiver 13 and the transmitter 15 with the velocity of the vehicle A. The controller 31 also includes a manual activation input 71. In the embodiment illustrated as shown in FIG. 4, the manual input is connected to a foot switch 73, which allows the system user to manipulate the transceiver 13 and the transmitter. 15 for the diffusion. In operation, the warning system of Figure 4 operates in one of a plurality of alternative modes of operation (e.g., eight) . The mode of operation can be selected manually by means of keystrokes to a switch 75 on the control panel 33. Alternatively, a change in the status of one of the automatic, remote or manual inputs causes the controller to 31 respond under program control to automatically switch to an appropriate mode of operation. In order to inform the user of the current mode of operation of the system, a portion of the display screen 55 can be dedicated to displaying a number from zero (0) to seven (7). According to a predetermined convention, each of the displayed numbers corresponds to one of the eight modes of operation of the system 11. Preferably, one of the operating modes is a "useless" mode, wherein neither the transmitter 15 nor the transceiver 13 are manipulated or spread. A second mode is a "primary" mode, which is selected automatically when the emergency vehicle is moving as detected by the controller 31 from the state of sensors 65 and 69. A third mode is a "secondary" mode , which is automatically selected when the vehicle is static as is also detected by the controller 31 from the status of the sensors 65 and 69. In a contemplated embodiment, the third mode of operation is reserved so that a customer message is formed in the scene of an emergency. When the system is energized first, check that the parking / neutral switch 65 detects if the vehicle is static or moving and selects the appropriate operating modes, primary or secondary. The operator has the option to select other modes of operation by pressing the mode switch 75. Returning to the switches and display screens of the control panel 33, pressing a key to a transmit switch (XMIT) 77 causes the controller 31 manipulates the transmitter 15 and the transceiver 13, thereby manually initiating the transmission of the RF message for a selected mode. In order to indicate the user with respect to the. condition of the switch 77, illuminates when the transmitter 15 is tampered with. A second keystroke to the XMIT 77 switch will disable the transmitter 15 and the transceiver 13 and turn off the illumination of the switch. An on / off switch 79 allows the power of the system to be turned on and off from the front of the control panel 33. To indicate to the user the state of the switch 79, it illuminates when the power of the system is applied. A recording / playback switch 85 allows the system to configure a message from the client. Pressing this button without any other press will allow playback of selected pre-recorded messages. Oppressing this button simultaneously with a push-to-talk (PTT) switch 81 allows the customer's message to be recorded. The PTT switch 81 activates a microphone 83 to record audio messages from the client as explained more fully hereinafter. A piezoelectric alarm 87 is activated when the transceiver 13 receives a warning signal from another transceiver, thereby informing the operator about the proximity of another emergency vehicle. Also, the signal from the piezoelectric alarm 87 directs the operator's attention to the alphanumeric display 55 for additional information that may have been transmitted. As an additional visual indication, a CAUTION indicator lamp 89 flashes when the system detects a signal from another vehicle. Figure 5 is a block diagram of the controller 31, the transmitter 15 and the transceiver 13. The controller 31 includes a microprocessor section that includes a central processing unit ("CPU") 52. The CPU 52 operates in a conventional manner under control of a program memory 54. Also, as part of its basic architecture, a RAM 56 communicates with the CPU 52 in a conventional manner through a bus 57. Through the input / output circuitry 201, the CPU 52 receives various input signals from the audio / visual system 232, the sensors 231 and the foot switch 73 as discussed in relation to Figure 4. In response to these inputs, the CPU 52 manipulates the transceiver 13 and the transmitter 15 in accordance with the operating modes of the controller 31. In response to the reception of digital information at the frequency Fx through the transceiver 13, the CPU provides an output on a line 60 to the display 55, the piezoelectric buzzer 87 and the indicator lamp of CAUTION 89 of the control panel 33. As shown in FIG. discussed hereinafter, the transceiver 13 also operates the horn 246 if the information in the frequency Fx is in an analogous format. The input / output circuitry 202 communicates with the CPU 52 and the transceiver 13 and the transmitter 15 so that the controller 31 manipulates the transmitter and the transceiver as well as sending and receiving digital data as explained more fully here. onwards. An EEPROM 203 contains a menu of proposed messages for transmission through digital coding either as a signal encoded by RBDS on the sideband of the carrier frequency F0 transmitted by the transmitter 15 or as a digital signal broadcast by the transceiver 13 via the amplitude modulation of the frequency, carrier Fx. The menu is set below as TABLE I. TABLE I MENU OF DEPLOYMENT MESSAGES GROUP 1 GROUP 2 GROUP 3 A POLICE PRODUCE LIMIT-N B FIREMEN GO RIGHT LIMIT-S C DOCTORS CAUTION LIMIT-E DIMENSION LIMIT-O E HIGH LIMIT-NE F IR TO THE LEFT LIMIT-SE G DETERMINANTS LIMIT- NO H DANGER LIMIT-SO I VEHICLE ID According to the invention, each mode of operation of the system may select one of the messages of each of Groups 1, 2, and 3 of the menu. The selected Group 1 message is transmitted by both the transceiver 13 and the transmitter 15. In the receiving system 11 ', the selected message from Group I is displayed on the first line of the three (3) lines of text available in the display screen 55 '. Similarly, in the receiver 17, the message is displayed on the first of its two lines of text on the display screen. Preferably, in each mode of the controller 31, the transmitter 15 and the transceiver 13 transmit different messages from Group 2, which will be displayed as a second line of text in each of the receiving transceiver 13 'and the receiver 17. Specifically, the CPU 52 provides the transmitter 15 with one of the messages A to H of Group 2, which is displayed as a second line of text on the display screen of the receiver 17. However, for a second line of text to be broadcast by transceiver 13, the CPU selects article I of Group 2, which is an identification code of the broadcast vehicle. Finally, a selected message from Group 3 of the menu is also provided to the transceiver 13 by means of the CPU 52 for transmission. The selected Group 3 message is displayed on the display screen 55 'of the receiving system 11' as a third line of text. Since the receiver 17 display screen has only two lines of text, the transmitter 15 does not broadcast a message from Group 3. In one example of a deployment data transmission, the CPU can select Group 1 (B), Group 2 (1) and Group 3 (H) to transmit through transceiver 13 in one of the modes of operation of the system 11. Obviously, the selection of the message segment of Group 3 requires a periodic update, which handles the CPU 52 in a conventional manner. In the receiving system 11 ', the display 55' provides the following text: FIRE (ID No. ###) LIMIT-SO In the receiver 17, the first line of text is the same as the first line of text diffused to the reception system 11 '. However, the second text line is selected by the CPU 52 from articles A to H of the Group 2. For example, in the following example, the display screen in the receiver 17 can be read as follows: FIRE IR A RIGHT, assuming that the CPU 52 selects the article B of Group 2 for its diffusion in an RBDS format on the sideband of the carrier frequency F0 broadcast by the transmitter 15. As shown in Figure 5, a signal encoder Emergency Vehicle (EVS) 68 of the transceiver receives control and message data in a digital format, coming from the CPU 52, in order to start an emergency vehicle-to-emergency vehicle transmission (EV-a-EV) . Any number of conventional coding schemes can be employed by the encoder 68. The EVS encoder 68 provides an output signal to a switch 70, which also receives a speech analog signal from the memory 220 as explained more fully from now on . Depending on the state of the switch 70, either digital or analog (audio) signals are passed to the transmitter 204. The state of the switch 70 is controlled by the CPU 52, depending on whether digital data or voice analog messages are supplied to the transceiver 13. From transmitter 204, the modulated carrier frequency Fx is supplied to a variable amplifier 205. Variable amplifier 205 includes a gain control unit circuit (not shown) under the control of CPU 52 to provide a gain variable to the signal coming from the transmitter 204. Specifically, the gain of the amplifier 205 varies between minimum and maximum values in a functional relationship with the vehicle speed as detected by the speedometer 69. In one implementation, the CPU 52 uses a simple linear function between minimum and maximum speeds. The amplified carrier frequency F? from the amplifier 205 is supplied to a receiver / transmitter switch 112 which connects the output of the amplifier to one or both antennas 20a and 20b, depending on the state of the switch 206. The switch 206 is controlled by the CPU 52 to change the radiation pattern of the broadcast signal F. Preferably, the state of the switch 206 is determined by the operation mode of the controller 31. When the transceiver 13 is in the reception mode, the switch 112 connects the antennas 20a and 20b to an RF receiver 116. From the receiver 116, the demodulated voice signals are routed to an amplifier 207 and then to a horn 246. The demodulated digital signals are sent to a decoder 148 and then supplied to the CPU 52 through the input / output circuitry 202. After reception by the transceiver 13 of an EV digital signal -a-EV, the controller 31 provides appropriate output signals to the display 55 of the control panel 33 to indicate that the reception data is being transmitted by another emergency vehicle as discussed in connection with TABLE 1. At the same time, the dedicated CAUTION lamp 89 illuminates (flashes) and the piezo alarm 87 sounds indicating that another emergency vehicle signal is being received. Preferably, the message transmitted by the transceiver 13 for reception by another vehicle is formatted to be displayed in each of the three lines of text available on the display screen 55. As previously indicated, the message can be divided into three sections. The first section of the message is displayed on the first line of the display screen 55. This section of the EV-a-EV message is the same as the message sent to the display screen of the receiver 17 by means of the transmitter 15. The second line of text displayed by the display screen 55 is the identification number or code of the transmission vehicle. The third line of text is the direction in which the vehicle moves. A more sophisticated display screen in the control panel 33 would allow the total use of a global positioning device 208 illustrated in Figure 4. Specifically, an image representing the transmission vehicle could be displayed in a location on a display screen in relationship to a fixed central position that represents the receiving vehicle. The circumferential and radial position of the image with respect to the central position would provide an easy visual reference for the user to determine the relative position of the transmission vehicle with respect to the receiving vehicle - ie, forward, left, to the right or behind. In addition, the image could provide direction and velocity information by being in the form of a vector. By superimposing a map of streets and roads on the display screen, a complete visualization of the operation of the transmission vehicle is obtained. In order to transmit voice or siren signals, an analogous memory 220 is directed by the CPU 52 to output voice or siren messages analogous to one or both of the transceiver 13 and transmitter 15. Preferably, the analog memory 220 is a device Recording / Voice Recording ISD1012A / 1016A / 1020A, produced by Information Storage Devices, Inc. of San Jose California. The preliminary specification sheet for these devices presented in February 1992 is incorporated herein by reference. Also, U.S. Patent Nos. 4,890,259, 4,989,179 and 5,241,494, which are directed to these services, are also incorporated herein by reference.

According to the invention, the analogue memory 220 contains a menu of voice phrases that can be assembled by the CPU 52 in an emergency message broadcast by one or both of the transceiver 13 and transmitter 15. An example of a menu of segments of voice contained in the analogue memory 220 and accessible by means of an appropriate addressing for the CPU 52, are set down below as TABLE II. TABLE II MENU OF AUDIO MESSAGES FIRST SEGMENT SECOND MOTION CLOSURE Nearby Police Please stay out of the way B Close Firefighter Go straight and stop C Near Ambulance Proceed with caution D Near Ambulance Slow down E High now Stop now F Please move to the left Accident ahead Pass with caution H Danger in the highway please be careful STATIC A Police on the road Please stay out of the way B Fireman on the road Go straight and stop C Near ambulance Proceed with caution D Ambulance on the road Decrease the speed E High now Stop now F Crash forward pass with caution G Danger on the highway please be careful In operation, a voice switch 211 directs the voice segments directed to one or more of the transceiver 13, the transmitter 15 and the horn 246, depending on the operation mode of the controller 31. To transmit the voice segments through the transceiver 13 , the switch 211 provides the signal analogous to the switch 70, which is controlled by the CPU 52 to provide the analog signal to the input of the transmitter 204. The analog frequency Fx frequency is modulated by the audio frequencies of the analog voice messages. in a conventional way. From the transmitter 204, the modulated signal is processed by the amplifier 205, the switch 112 and the switch 206 in the same manner as previously described in relation to the digital signals coming from the CPU 52 and the EEPROM 203. The transmitter 204 of the Transmitter 13 is manipulated by controller 31 via line 221. Depending on the mode of operation of controller 31, voice switch 211 can also direct analog signals emitted by analog memory 220 to transmitter 15. Depending on the mode of operation selected, one or both of the transceiver 13 and the transmitter 15 may be broadcasting audio signals. Also, each of the transceiver 13 and transmitter 15 can broadcast an audio message different from one another. As indicated in Figure 5, the voice segments are supplied to a transmitter or modulator 212 in the transmitter 15, where the carrier frequency F0 is modulated by the audio frequencies of the speech segments in a conventional manner. Like the circuitry of the transceiver 13, the modulated output of the transmitter / modulator 212 is supplied to a variable power amplifier 213 to operate the antennas 19a and 19b. Like the variable power amplifier 205 of the transceiver 13, the variable power amplifier 213 of the transmitter 15 has a variable gain whose setting is controlled by the CPU 52 through the input / output circuit 202 between minimum and maximum values. Also as the transceiver 13, a switch 214 responds to the CPU 52 to connect one or both antennas 19a and 19b to the power amplifier 213. Preferably, the audio message is read repeatedly from the analog memory 220 and is broadcast by the transmitter. 15. With the analog or audio signal broadcast by the transmitter 15, an RBDS coding signal transmitted on a sideband according to the invention is also transmitted. In general, the format of the RBDS signal is in accordance with Figure 6 and, in particular, is in accordance with the parameters for category 31 of the PTY code, which has been reserved for "emergency" functions. As described in the RBDS specification previously identified herein, the digital data is encoded in an RBDS format in an encoder 215 of the transmitter 15. The data encoded by RBDS is supplied to an amplitude modulator 216 for the purpose of modulating a subcarrier frequency provided by a generator 217. The output of the amplitude modulator 216 is the subcarrier of the amplitude modulated generator 217 according to the RBDS data from the encoder 215. The modulated subcarrier signal is added to the analog signal from the analog memory 220 in the totalization circuit 218. The combined digital and analog signals are then modulated in a conventional manner by the transmitter 212. Before the controller 31 terminates a transmission by the transmitter 15, a signal encoded by RBDS is transmitted , returning all captured receivers 17 to their previous mode of operation. The transmitter 15 is then turned off by the controller 31 by applying the appropriate signal to the transmitter 212 via the line 219. If the proposed RBDS signal to terminate the transmission is not received by the receiver 17, it will detect the loss of the frequency of F0 transmission and it will reset after a time out. The operator of the emergency vehicle can change the digital messages transmitted by the transmitter 15 and transceiver 13 by pressing the "mode" switch 75 on the control panel 33. By keeping this momentary type switch in its depressed position, the message options library contained in the EEPROM 203 is scrolled through the display screen 55. When the switch 75 is released, the displayed alphanumeric message is selected for broadcast in the selected mode with any audio signal associated with it. from the analogue memory 220. A voice audio signal from the client can be recorded in the analogue memory 220 at any time for later broadcasting by the transceiver 13 and / or the transmitter 15. To record a voice signal, the operator presses the recording / playback switch 85 over the control panel 33 and the PTT switch 81 and speaks into the microphone 83. The CPU 52 responds to the activation of both switches upon closing the microphone switch 209, which allows analog input to the voice / message memory 220. The operator can check the registered audio voice signal by pressing the recording / playback switch 85 after which the PTT switch has been released. When the voice message is acceptable to the operator, the mode switch 75 is pressed, which identifies the message with the selected mode. Pressing the XMIT 77 button will then send the message. This message replaces any other message that was being sent in the current mode of the system. This new constructed message will be repeated until the system is turned off or the controller 31 receives another entry command. The operator can broadcast a live message at any time. The oppression of the "PTT" switch 81 transfers the system 11 to an operating mode that couples the microphone 83 directly to the transmitter 15. Specifically, the CPU 52 manipulates the transmitter 15 and provides it with an appropriate data signal for coding by RBDS, which is proposed to capture the control of the receiver 17. In order to ensure that the user of the receiver 17 understands that an emergency voice message is being received, an alert tone is broadcast by the transmitter 15 before transmission of the voice message. To indicate to the user of the system 11 that the system is ready to transmit a live message, the display screen 55 will display the word "SPEAK", indicating which alert tone has been sent and that the voice channel is available. If the system 11 is in an operation mode when the PTT switch 81 is pressed, the controller 31 is transferred to the mode to broadcast the message live. Figure 7 is a logic flow diagram of the operation of the controller 31 as illustrated in Figure 5. As shown therein, the CPU 52 is initially powered in step 400 and performs a conventional initialization sequence ( cleans the memory, loads the program and the like) in step 402 that configures the hardware and software of the system. The CPU 52 then performs a diagnostic routine in step 404 that verifies the operation of the system. If the diagnostic routine detects a fault in step 406, the piezo alarm 87 sounds and an error message is displayed on the alphanumeric display 55 in step 408. The system is interrupted as well. If the diagnostic routine passes in step 406, the CPU 52 then seeks an interrupt in step 410. If no interruption is detected in step 410, the system 11 processes a power-down mode in step 416 and waits an interruption After an interruption is detected in step 410, the controller 31 first checks to see if it is a serial (remote) function, which is any information transmitted by another emergency vehicle. If this type of interruption is detected in step 416, then the CPU 52 decodes the transmission in step 418 and provides the appropriate visual message in step 420 by doing something or all of the following: flashing the warning lamp.; ring the alarm piezo 87; display information on the alphanumeric display screen 55; and, providing an audio message through the speaker 246. If the interrupt detected in step 416 does not come from the transceiver 13, then the controller 31 evaluates the interruption in step 422 as a "local" interrupt generated from the panel control 33, sensors 231 or audio / visual system 232. The CPU decodes this local interrupt in step 422, identifies what is changed in step 424, creates a new message in step 426 and executes the message or function in step 428. In one example, the interruption may be generated by a change in the state of one of the sensors 231, foot switch 73 or audio / visual 232 system. In response to this state change, the controller 31 can change the modes for broadcasting appropriate RF signals through the transmitter 15 and the transceiver 13. If the interruption in step 410 is neither serial nor local, the resulting unknown interrupt is presented again to interrupt pir 410 for further processing. Once the messages 420 or 428 deploy or issue, respectively, the controller 31 returns to step 410 for further processing. Returning to the block diagram of the receiver 17 in FIG. 8, the receiver 17 includes two front ends 306 and 308, each including a tuner and a demodulator. The outputs 310 and 311 of each of the front ends 306 and 308, respectively, provide an audio frequency signal to an audio switch 312. In a conventional application, the receiver 17 has both front ends 306 and 308 tuned to the same radio frequency. Such a configuration is useful when, for example, the vehicle of the receiver 17 stops at a high light and the frequency at which the receiver is tuned becomes weak. This double-ended front end configuration of the receiver 17 allows a CPU 320 to select the strongest signal from the two front ends 306 and 308 in order to maximize the strength of the signal. Advantageously, the invention uses the second front end 306 under the control of the CPU 320 to monitor RBDS type broadcasts. After reception of the emergency signals at the carrier frequency F0 and its RBDS sideband, the CPU 320 performs the appropriate decoded function. This second front end 306 does not need to have its fixed tuning at the frequency F0 in order for the receiver 17 to operate in accordance with the invention. For example, the front end 306 can scan the FM band for the specific sideband information. It is important to note that advances in technology could make the second front end obsolete; a simple front end with very fast scanning capabilities, or other features of RBDS may allow in the future the use of a single front end to carry out the functions of the two front ends 306 and 308. The central processing unit or CPU 320 of the receiver 17 operates in a conventional manner under the control of a program memory 322. In response to the reception of emergency RBDS data, the CPU 320 provides outputs to a display screen 332, bell actuator 330 and a light CAUTION 328. In addition, the CPU 320 controls an audio switch 312 and a CD / tape player 314, which controls the audio signal input to an amplifier 336 and a speaker 334. In normal operation, the audio signals from a commercial transmitter are supplied to the audio switch 312 from one of the front ends 306 and 308. The commercial transmissions are handled as follows: all data of the band are decoded by the decoder 316 and are supplied to the CPU 320 via line 318 for processing with the help of the program memory 322. If the sideband data tells the CPU 320 to turn on its lights 328, enable the bell actuator 330 or handle the display screen 332, those activities is carried out. The listener will listen to a commercial broadcast on speaker 334 and will see lights 328 and display screen 332, as they respond to any data from the sideband. The user control of the receiver 17 is achieved in a well-known manner by means of the switches 338. If the front end 306 receives a transmission on the frequency F0 from the transmitter 15 of the system 11, the decoder 316 decodes the emergency data from the sideband and presents them to the CPU 320 for processing. Under the control of the program, the CPU recognizes the data as category 31 of the PTY code (ie emergency code) and reacts according to the above. Specifically, the CPU 320 switches the audio switch 312 from its current position (i.e., off, input from the front end 308 or input from the tape / CD player 314) to an input from the front end 306, which is the demodulated audio emergency signal. The amplifier 336 is set by the CPU 320 at a predetermined level according to whether it is best to broadcast the audio emergency signal. Depending on the precise nature of the sideband data, the CPU 320 will also handle the display screen 332 to display information in a text format (eg, "FIRE FOLLOWS STRAIGHT", see Figure 10), will activate the bell actuator 330 and the lights 328. The bell actuator 330 provides a tone to the speaker 334, which can be used to announce the transition of the receiver 17 to an emergency operation mode. Once the receiver 17 is outside the range of the transmitter 15, the CPU 320 controller will return the system to the normal operating mode it was in before receiving the emergency signal. Figure 9 is a logical flow diagram of the program in the program memory 322 of the receiver 17 shown in Figure 8. The receiver 17 is initially turned on in step 500 and the CPU 320 performs an initialization sequence in the step 502. In the sequence of step 502, the CPU 320 configures the hardware and software of the receiver 17 in a manner well understood by those skilled in the art. The CPU 320 then carries out a diagnostic routine in step 504 that verifies the operation of the system. If the CPU 320 determines that a failure has occurred in step 506, the bell actuator 330 is activated to sound an alarm and an error message is displayed on the alphanumeric display 332 in step 510. The CPU 320 then returns to the stage 504 and it is interrupted. On the other hand, if the diagnostic routine passes in step 506, the CPU 320 goes to step 508 and in step 514 it determines whether an interrupt has been received. If no interruption is detected in step 508, the CPU 320 advances to a power down mode in step 512 and cycles through step 508 that wait for an interruption. When an interruption is detected in step 508, the CPU 320 first determines in step 514 whether the interruption is an interruption related to the operation of the receiver in accordance with the RBDS Standard or an interrupt generated by a user for operations such as changing volume or change the seasons. If the detected interruption is a signal from the front ends 306 or 308, the CPU 320 decodes the transmission in step 518 and determines whether the data is an emergency code according to the invention or a user defined code. A user-defined code can be a PTY code entry from the RBDS switches 38 on the front panel 350 (see Figure 10) which asks the receiver 17 to search for a station having the same PTY code. If the decoded message is an emergency code (e.g., PTY code 31), the CPU 320 processes the warning signal in step 520. Specifically, the CPU 320 connects the front end 306 to the amplifier 336 by means of the changeover switch. 312. The CPU 320 also controls the display screen 332, the bell actuator 330 and the lights 328 as previously discussed in connection with Figure 8. When the warning function is fully activated, the CPU 320 branches off from the new to stage 508 and continue looking for an interruption. If the detected interrupt is not an interrupt by RDS, the system processes the interrupt as a user function in step 516. If the interrupt detected by the CPU 320 in step 518 is an RBDS command defined by a user, the CPU 320 advances to step 522 and processes the user's demand. The system then returns to stage 508 and monitors additional interruptions. From the above detailed description, it will be appreciated that the alert system 11 provides an effective broadcast area that complements the effective alert area provided by conventional audio / visual systems such as the system 332 in the illustrated mode. When using the RBDS Standard, conventional receivers compatible with the RBDS such as the receiver 17 can be remotely controlled by the alert system 11 in order to improve and complement the audio / visual system's ability to alert each one in the local area. Because the transmitter 15 broadcasts an RF emergency signal in accordance with the RBDS Standard, the receiver of the emergency signal does not need to possess special equipment in order to benefit from the improvement provided by the alert system 11. According to it is suggested by the alternative embodiments illustrated in Figures 3A to 3E, the alert system 11 may be made of several different architectures. However, in all these architectures, the transmitter 15 complements an audio / visual system in order to control the RBDS compatible receivers in the same approximate local area covered by the audio / visual system. Each patent and publication identified herein is incorporated herein by reference.

Claims (31)

1. NOVELTY OF THE INVENTION Having described the present invention, it is considered as a novelty and therefore the property described in the following claims is claimed as property. 1. A system for broadcasting an emergency warning through an area around a site, the system comprising: a source at the site of an audible or visual warning signal detectable by at least one of the human senses, - a transmitter on the site for broadcasting an electromagnetic warning signal within a tunable bandwidth of a standard radio receiver to receive commercial broadcasts, with at least part of the electromagnetic warning signal encoded in an RDS compatible format; a power amplifier within the transmitter whose power ratio provides an effective range of the electromagnetic warning signal that complements an effective range of the audible or visual signal and is approximately coextensive with it, and means for detecting the electromagnetic warning signal within its effective range and in response to it by tuning the receiver to a frequency carrying the electromagnetic warning signal. The system according to claim 1, characterized in that the electromagnetic warning signal includes both the carrier frequency modulated by a signal within an audible frequency range and a sideband of the carrier frequency encoded in the RDS compatible format. The system according to claim 1, characterized in that it includes an interface that links the source of the audible or visual warning signal and the transmitter to provide a synchronized relationship between a broadcast of the audible or visual warning signal and the broadcast of the electromagnetic warning sign. The system according to claim 3, characterized in that the synchronized relation is a synchronized broadcast of the audible or visual and electromagnetic warning signals. The system according to claim 1, characterized in that it includes a variable gain control for controlling the power ratio of the power amplifier in response to a vehicular operation parameter. The system according to claim 1, characterized in that the transmitter includes at least two antenna configurations that respond to a user control to select a particular form of an effective diffusion area of the electromagnetic warning signal. The system according to claim 1, characterized in that the source site and the transmitter is a mobile vehicle. The system according to claim 1, characterized in that the source site and the transmitter is a fixed and static platform. The system according to claim 3, characterized in that the interface includes a user input to both operate the source to broadcast the audible or visual warning signal and to manipulate the transmitter to broadcast the electromagnetic warning signal. The system according to claim 1, characterized in that the tunable bandwidth is selected from two bandwidths of 54 KHz at 160 KHz and from 87.5 MHz to 108.0 MHz when the transmitter is broadcasting in the United States. The system according to claim 1, characterized in that the tunable bandwidth is a bandwidth for commercial broadcasts in a nation that is a member of the European Broadcasting Union. The system according to claim 1, characterized in that the RDS compatible format is the United States RBDS Standard produced by the RBDS subgroup of the National Radio Systems Committee (NRSC) guaranteed by the Industry Association of Electronics (EIA) and the National Association of Diffusers (NAB) 13. A signaling system on board an emergency vehicle to provide an advance warning of approaching the vehicle, the system comprising: a transmitter for broadcasting a first emergency warning signal within a tunable bandwidth of a standard radio receiver to receive commercial broadcasts; a transceiver for broadcasting or receiving a second emergency warning signal proposed to provide an emergency vehicle-to-emergency vehicle link outside the tunable bandwidth of the standard radio receiver; a source of emergency warning signs, first and second; and a processor that responds to an input in a user interface for manipulating the transceiver and the transmitter to broadcast the first and second emergency warning signals. The signaling system according to claim 13, characterized in that the first emergency warning signal includes control signals in a format compatible with RDS, which propagate through a sideband of a carrier frequency. 15. The signaling system according to claim 14, characterized in that the transmitter includes a modulator for modulating the carrier frequency with an alert signal in an audible range of frequencies. 16. The signaling system according to claim 13, characterized in that it includes a sensor on board the vehicle for detecting a value of a parameter indicative of an operation state of the vehicle and providing a signal representing the value for the processor. 17. The signaling system according to claim 16, characterized in that the second emergency warning signal broadcasted by the transceiver includes information with respect to the value of the parameter indicative of the operating state of the vehicle. 18. An apparatus comprising a system for propagating advance signals in the form of acoustic or light signals; a controller to detect a change in a system operating condition; a transmitter that responds to the controller to transmit (1) an RF carrier frequency F0 modulated by an audio signal containing emergency information and (2) a sideband frequency of the carrier frequency F0 modulated by information encoded by RDS. The apparatus according to claim 18, characterized in that it includes a receiver for demodulating the RF frequency carrier frequency F0 and the modulated sideband frequency, including the receiver means responsive to the information encoded by RDS at the sideband frequency for spread the audio signal as an acoustic signal. 20. The apparatus according to claim 18, characterized in that the system comprises a siren. 21. The apparatus according to claim 18, characterized in that the site is a fixed and static site. 22. The apparatus according to claim 18, characterized in that the site is a mobile vehicle. The system according to claim 1, characterized in that the means for tuning the receiver includes circuitry that responds to electrical signals coming from a front end of the receiver. 24. The system according to claim 5, characterized in that the vehicular operation parameter is the speed. 25. A system for broadcasting an emergency warning through an area around a site, the system comprising: a source at the site of an audible or visual warning signal detectable by at least one of the human senses; an on-site transmitter for broadcasting an electromagnetic warning signal within a tunable bandwidth of a standard radio receiver to receive commercial broadcasts, with at least part of the electromagnetic warning signal encoded in an RDS-compatible format; a power amplifier within the transmitter whose power ratio provides an effective range of the electromagnetic warning signal that complements an effective range of the audible or visual signal and that is approximately coextensive with it; and an interface that links the transmitter and the source of the audible or visual warning signal to provide a synchronized relationship between the broadcast of the audible or visual warning signal and the broadcast of the electromagnetic warning signal. 26. The system according to claim 25, characterized in that it includes a variable gain control for controlling the power ratio of the power amplifier in response to a site operation parameter. 27. The system according to claim 26, characterized in that the site is a vehicle and the operating parameter is the speed. 28. A system for broadcasting an emergency warning through an area around a fixed and static site, the system comprising: a source of an audible or visual warning signal at the fixed and static location detectable by at least one of the human senses, a static and fixed site transmitter for broadcasting an electromagnetic warning signal within a tunable bandwidth of a standard radio receiver to receive commercial broadcasts, with at least part of the electromagnetic warning signal encoded in a compatible format with RDS; and a power amplifier within the transmitter whose power ratio provides an effective range of the electromagnetic warning signal that complements an effective range of the audible or visual signal and is approximately coextensive with it. The system according to claim 28, characterized in that it includes an interface that links the transmitter and the source of the audible or visual warning signal to provide a synchronized relationship between a broadcast of the audible or visual signal and the broadcast of the signal of electromagnetic warning. The system according to claim 29, characterized in that the synchronized relation is a synchronized broadcast of the audible or visual warning signal and the electromagnetic warning signal. The system according to claim 29, characterized in that the interface includes a user input to both operate the source to broadcast the audible or visual warning signal and to manipulate the transmitter to broadcast the electromagnetic warning signal.