RELATED APPLICATIONS

The present application claims priority from Australian provisional patent application no. 2022901402 filed on 24 May 2022, the entire contents of which are incorporated herein by reference.

FIELD OF INVENTION

This present invention relates generally to a communication system for communicating information across large audiences, and in particular, to a disaster communication system that can be used to provide relevant information to a population about a disaster event.

BACKGROUND ART

The ability to provide effective communication systems for authorities or government bodies to communicate with the general population is fundamental to good governance and public safety. In situations where the safety and wellbeing of the population is under threat, there is a significant need to ensure that the population receives information in a timely and relevant manner. This is important to not only advise the population on important issues relevant to their immediate safety, but to also provide a degree of comfort and assurance to the population that the governing bodies are acting accordingly and are aware of the situation and it’s severity.

In this regard, a variety of broadcast systems have been proposed for this purpose, with varying degrees of success. Early systems for disaster warning included church bells or sirens, which were able to be heard at a distance but which are unable to convey any relevant information. Similarly, house-to-house alerts as well as megaphones and Public Address Systems (PAS) have been used for such purposes, and whilst they are able to deliver relevant information to the immediate population, but they require active personnel to deliver the warning message and are only able to broadcast to the immediate area.

Broadcast systems have been proposed to indiscriminately broadcast a message over a wide area. Such systems have the ability to communicate a message to a large population. However, in situations where the message may only be relevant to a small proportion of that population, such broadcast systems has the potential to cause undue concern and/or panic to any individuals within the region to whom the message is not relevant. This has the potential to hamper emergency services and create mass confusion across the wider population. Such systems may use local telecommunication networks to deliver the message. However, as the need to broadcast information is often a direct result of a catastrophic event or natural disaster: such as a bushfire; cyclone; tsunami; terrorist attack; or the like, in many instances such telecommunication networks are not functioning or supportive infrastructure, such as transmission towers or mobile phone towers, has been damaged, making them largely ineffective at a time when they are most required.

Thus, there is a need to provide a simple and effective communication system for use in disaster situations that provides an instant and clear means for communicating a relevant message to a mass audience and which does not rely on a conventional terrestrial infrastructure.

The above references to and descriptions of prior proposals or products are not intended to be, and are not to be construed as, statements or admissions of common general knowledge in the art. In particular, the above prior art discussion does not relate to what is commonly or well known by the person skilled in the art, but assists in the understanding of the inventive step of the present invention of which the identification of pertinent prior art proposals is but one part.

STATEMENT OF INVENTION

The invention according to one or more aspects is as defined in the independent claims. Some optional and/or preferred features of the invention are defined in the dependent claims.

Accordingly, in one aspect of the invention there is provided a communication system for communicating targeted information to regions within a determined area comprising: a plurality of transmitter units remotely positioned within the determined area, each transmitter unit configured to operate in either a first mode where the transmitter unit receives instructions to broadcast a signal from a remote authorised source or a second mode where the transmitter unit is used to generate a signal to broadcast; a plurality of receiver units positioned within the regions of the determined area; each receiver unit configured to receive the signal broadcast from at least one transmitter unit and to emit an announcement in accordance with the received signal. The signal broadcast by the transmitter unit may be a VHF or UHF radio signal.

The transmitter unit, when in the first mode, may receive the instructions from a remote control centre via a server. The remote control centre may comprise one or more computers configured to operate software for generating instructions in accordance with data received by the remote control centre. The instructions may comprise pre-recorded announcements.

The signal broadcast by the transmitter unit may comprise two payloads, an audio payload and a signalling payload.

The audio payload may contain an audio message. The audio message may be selected from multiple classes of audio messages.

The signalling payload may contain information required to select one or more of the plurality of receiver units to activate one or more features of the selected receiver unit. The one or more features of the selected receiver unit to be activated may be determined based on a class of the audio message received in the audio payload. In one embodiment, the one or more features of the selected receiver unit may include an audio playback feature for audibly transmitting the audio message. In another embodiment, the one or more features of the selected receiver unit may include a visual indicator for displaying a visual indication of a received message.

The audio payload and a signalling payload may be broadcast by the transmitter unit across a frequency range of between 82MHz to 108MHz in steps of 200kHz and a bandwidth of each frequency may be approximately 100kHz. The audio payload may be broadcast by the transmitter over an insecure channel and the signalling payload may be broadcast by the transmitter over a secure channel.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention may be better understood from the following non-limiting description of preferred embodiments, in which:

Fig. 1 is a block diagram depicting the communication system of the present invention in accordance with one embodiment;

Fig. 2 is diagram depicting the components of the control centre of the communication system of Fig. 1; and

Fig. 3 is a diagram depicting the components of the remote transmitter and receiver units of the communication system of Fig. 1. DETAILED DESCRIPTION OF THE DRAWINGS

Preferred features of the present invention will now be described with particular reference to the accompanying drawings. However, it is to be understood that the features illustrated in and described with reference to the drawings are not to be construed as limiting on the scope of the invention.

The present invention will be described below in relation to a disaster communication system capable of delivering targeted information to sections of a population in a disaster setting. However, it will be appreciated that the system of the present invention may be used for a variety of different purposes to deliver information across a population, as will be appreciated by those skilled in the art.

Referring to Fig. 1, a schematic block diagram of the communication system 10 in accordance with one embodiment of the present invention is depicted. The system 10 can be generally considered to comprise four main components, as depicted.

The first component is the control centre 12. The control centre 12 will be described in more detail below but generally comprises a computer system comprising a number of computers and data storage components. The computer system is capable of operating software to control the overall system 10 and can be located remotely from the site receiving the communications, typically in a safe environment unaffected by the disaster. The control centre 12 is able to receive information from remote sources, such as weather bureaus, emergency centres, satellite information, and process the information for communication to the relevant population areas.

The second component of the system 10 is the control centre servers 14. The control centre servers 14 are dedicated servers that respond to information commands received from the control centre 12 and communicate the information to remote transmitters 16 that are responsible for disseminating the information to the specific population regions identified by the control centre 12. The control centre servers 14 are able to monitor the status of each of the remote transmitters 16 to determine whether there are any problems with the remote transmitters 16 and to feed the status of each remote transmitter 16 back to the control centre 12. The control centre 12 may communicate with a number of individual control centre servers 14, with each of the control centre servers 14 responsible for a discrete number of remote transmitters 16. The control centre servers 14 use cryptographic protocols to securely communicate with both the remote transmitters 16 and the control centre 12 to ensure that the system 10 is operating in a safe and secure manner.

The remote transmitters 16 function as remote base stations and are located within a geographic area to provide coverage across that area. Each transmitter 16 is configured such that they function as a secure connected network, capable of transmitting information from the control centre 12 via the servers 14. The transmitters 16 are also configured with a touch screen computer processor such that they can function as a stand alone unit for sending information in the event of a network failure which prevents the transmitter from communicating with the remote server 14. The transmitters 16 are configured to communicate with receiver units 18 to broadcast the information, in a manner as will be described in more detail below.

The receiver units 18 are in the form of individual units operating in the VHF or UHF range. The receiver units 18 are configured to be installed in homes, apartments, offices and the like and to operate continuously in a quiet stand-by mode. The receiver units 18 are able to be operated on conventional mains power supplied by the local power grid, and have a battery backup in the event of a power grid failure. The battery power also allows the receiver unit 18 to be carried by a user in the event of an evacuation, such that the user will still be able to receive communications when outside of the building.

Each receiver unit 18 has a loud emergency alarm feature. The receiver units 18 are also capable of record and playback of messages as desired. It will be appreciated that there may be a large number of receiver units each capable of communicating with one or more transmitters as required.

An embodiment depicting a manner in which a control centre 12 of the present invention may be configured is shown in Fig. 2.

As previously discussed, the control centre 12 is generally located in a remote location, typically in a safe area with reliable power and communications. The control centre may comprise one or more computers 13 capable of operating the system software of the present invention. The computers 13 may be in the form of laptop or desktop computers and may operate under a conventional Windows® operating system.

Each computer 13 may be configured to communicate in a network environment via a FAN switch 20, or similar networking structure. To facilitate a coordinated approach to the management of the emergency situation, one or more large screens 11 may be connected to the network to display maps and system status to the controllers of the system. The software may integrate with existing mapping systems, such as GoogleMaps® or other Geographical Information Systems (GIS) such that the location and status of all transmitters 16 forming the system 10 can be identified using software controlled adaptive geofencing for the control of zone specific targeted messaging.

The computers 13, through the system software, are able to access a library of prerecorded messages and announcements which can be selected for sending to different geographical areas, depending upon the informational requirements of those areas. Unique messages and announcements can be created by way of a microphone as circumstances change and different geographical areas become affected.

The control centre 12 can receive up-to-date information regarding the event via a Wide Area Network (WAN) through the WAM router 21. As depicted in Fig. 2, the information may be obtained from externally controlled sensor units 22, such as seismic and oceanographic sensors. Weather alert stations 23 can also provide updates that can be received by the control centre 12 as well as satellite imagery of the geographic area provided through dedicated providers 24.

The control centre 12 houses one or more of the servers 14 of the present system. The servers 14 function to supervise announcements and message transfer between the software and the remote transmitters 16. The servers communicate with the computers 13 via the LAN switch 20 and communicate with the remote transmitters 16 via the WAN Router 21. Each signal sent from the servers 14 via the WAN Router 21 to the one or more remote transmitters 16 employs a Dynamic Host Configuration Protocol (DHCP) to manage and optimise communication between devices.

In use, each server 14 provides the ability for the control centre 12 to control the remote transmitters from the remote location. New or updated voice based communications can be remotely uploaded to selected transmitters 16 or all transmitters 16, as required. The functionality of each transmitter 16 is monitored and the status of each transmitter can be updated in the software of the computers 13. All transmissions sent from the servers 14 are stored and logged and are securely encrypted to prevent unauthorised access to the system 10.

Communications from the servers 14 are sent via the WAN router 21 to each or a selected transmitter 16 via one or more of a fibre network 25, cable network 26 or LTE network 27. Each signal is encrypted via a Secure Shell (SSH) protocol to improve security between the server 14 and the transmitter 16. Referring to Fig. 3, an embodiment of the present invention depicting a manner in which a transmitter 16 receives the signal from the server 14 is depicted.

Each transmitter 16 is associated with a cable modem 28a, a fibre optic modem 28b, LTE modem 28c and satellite modem 28d to connect with the appropriate network to receive the encoded signal and data from the server 14. The transmitter 16 may be connected to a mains electricity supply and comprises an alternative energy supply, in the form of rechargeable batteries 29 to supply power to the system in the event of a disruption to the mains power supply.

Each transmitter 16 is able to function as a base station for providing a local area broadcast with a coverage of up to 700 km ² . The transmitter includes a microphone such that in the event of the transmitter losing connection to the control centre, a local authorized officer can broadcast announcements for local distribution. In this regard, the transmitter 16 comprises a touchscreen to enable local control of the unit when the authorised officer enters a secure code. This will cause the transmitter to enter manual control mode whereby the authorised officer is able to use the microphone to broadcast announcements to receiver units in the local area.

Whilst in normal operation, each transmitter 16 is controlled from the control centre 12. However, there are two main scenarios that are relevant to allow a broadcast from a transmitter 16.

This may occur when the transmitter 16 has lost all communication with the control centre 12. In such a situation, the transmitter 16 displays a “lost signal” status on the touch screen. A local user is then able to enter their passcode via the touch screen and if the transmitter 16 accepts the passcode, the user can select a pre-recorded message or may use the microphone to broadcast a live message.

The other situation that may occur is when the transmitter 16 is still in communication with the control centre 12. The transmitter status showing that the transmitter is connected to the control centre is displayed on the touch screen of the transmitter 16. To allow a local user to gain control of the transmitter 16, the local user must contact the control centre 12 to obtain authorisation to broadcast locally on that transmitter 16. If granted, the user can select a pre-recorded message or may use the microphone to broadcast a live message. The control centre 12 can terminate the broadcast at any time.

Each transmitter 16 is configured to broadcast to local receiver units 18 installed in homes and business within the range of the transmitter 16. The messages are broadcast via a VHF or UHF transmitter 30 carried by the transmitter and are received as VHF or UHF radio signals by the receiver units 18.

Transmitters 16 can transmit across a maximum of 24 frequencies concurrently. Each frequency can be subdivided into two subchannels i.e., an audio subchannel and a signalling subchannel. In one embodiment, the frequency range is 82MHz to 108MHz in steps of 200kHz and the bandwidth of each frequency may be approximately 100kHz. Both subchannels are contained in this bandwidth. The audio subchannel contains the audio message. The audio subchannel is an insecure channel. The signalling subchannel contains information required to select the receiver units to activate their audio subchannel and other features such as discrimination between classes of audio messages. The signalling subchannel is a secure channel. In another embodiment, a frequency range of 130MHz to 900MHz may be used with steps of 12.5kHz. In such an embodiment, all signalling and audio messages may be transmitted in a digitally modulated format.

The signalling subchannel is used to provide different classes of audio messages. The control centre 12 transmits to all receiver units 18 (via all transmitters 16) or to selected receiver units 18 (via selected transmitters 16). Each receiver unit will react in accordance with the type of alert class that it has received.

In the receiver unit 18, the audible frequency and cadence can be varied depending on the intended content or audience. Table 1 sets out how this can be established:

TABLE 1

Different combinations of alert tone and cadence may be used to advise of different alert priorities or/and intended audiences.

It is possible for transmitter overlap to occur in situations where there are multiple transmitters 16 located within a small geographical area. This could be problematic if the transmitters 16 are transmitting on the same frequency at the same time. To minimise this problem, the control centre servers 14 can instruct selected transmitters 16 to transmit messages simultaneously across multiple frequencies. The control centre server 14 selects the transmitter 16 and the frequencies based upon their RF overlap regions. Upon transmission, each receiver unit 18 will lock to the first valid frequency that it tunes to, to receive ongoing messages. Alternatively, the transmitters 16 may transmit over several frequencies simultaneously to the receivers.

One frequency can be allocated to all receiver units 18. This provides a secure mechanism for emergency respondents to act. In some instances, additional frequencies could be used to transmit clear audio. This could be used in an insecure manner to alert the public via their receivers.

Each receiver unit 18 is able to be connected to mains electricity supply and has a battery backup, in an event where power supply is interrupted. Each unit 18 comprises an alarm capable of emitting a loud signal upon activation by the signal received from the transmitter 16, and upon a user depressing a button on the receiver unit 18, the alarm will be silenced and a clear voice announcement is emitted from the unit 18, via a speaker. Upon receipt of the signal from the transmitter, the signal is stored in a memory of the receiver unit and continues repeating until a new message is received.

Whilst receiver units 18 can only receive one frequency at a time, receiver units 18 are capable of tuning to one of several frequencies. Automatic frequency tuning can occur when a receiver unit 18 has not received a signal on the current frequency of the transmitter 16 for a predetermined period of time. This situation could occur if the receiver unit 18 is out of range of the transmitter 16 due to topographical limitations, or if the user has travelled to a different region which has a different frequency allocation. The situation could also occur when the transmitter is no longer active as may occur due to a fault in the transmitter 16, lack of maintenance of the transmitter 16 or infrastructure collapse. Similarly, this could be a result of a regulator changing the base station frequency allocation for the transmitter 16.

These issues can be resolved due to the receiver units 18 having an automatic tuning ability such that the receiver unit 18 user is always in contact with a transmitter 16 to be capable of receiving emergency alerts.

As the purpose of the present system 10 is to alert the public of an emergency, there is no guarantee that the user of the receiver unit 18 will be in the vicinity of the receiver unit 18 to know that an emergency alert has been activated.

As discussed above, the communication between the transmitters 16 and the receiver units 18 comprises two payloads: an audio payload and a signalling payload. The audio payload contains the audio message and there may be multiple classes of audio messages. The signalling payload contains information required to select the receiver units 18 to activate their audio and other features such as discrimination between classes of audio messages.

One of the classes of audio message is the “Emergency” class. This class is transmitted to the receiver units 18 to alert the public of an emergency. The detail of the emergency is contained in the audio message. When an emergency message is received, the receiver unit activates a visual indicator, an audible indicator and audio recording commences. This is the only class where the audio is recorded.

There are two scenarios that can occur when an emergency alert is received by the receiver unit 18.

In one scenario, the user of the receiver unit can see and/or hear the indicators on the receiver unit 18 while the emergency alert is still “on the air”. The user is able to immediately acknowledge the alert signal by toggling a button on the receiver unit 18, at which time the receiver unit 18 will deactivate the audible alert. The visual indicator will remain active and an audio message will be emitted and the message will be recorded.

In the other scenario, the user of the receiver unit 18 may not see or hear the indicators provided by the receiver unit 18 for a period of time. In this situation, the user may later arrive at the receiver unit 18 when the emergency message is no longer immediately active or “on the air”. In this regard, the receiver unit 18 will still provide an active visual indicator to the user, but the audible alert will be inactive. However, the audio message has been recorded in the receiver unit 18. As such, the user, upon seeing the active visual indicator on the receiver unit 18 will recognise that an emergency alert occurred in their absence. The user can then acknowledge the alert by toggling a button on the receiver unit 18, which will deactivate the visual indicator and emit the recorded message. The recorded message will keep playing until the user toggles the button again.

During use, the recording will stop when the transmission stops or when the recording capacity of the receiver unit 18 has been reached. In one embodiment, the recording capacity of the receiver unit may be around 120 seconds and can be extended with more memory. The user may playback the message at any time. The recorded message is erased when a new emergency alert is received, with the new audio message being recorded in place of the previous message. Such a system ensures that only the most recent and up-to-date message is being transmitted.

To ensure integrity of the system, each transmitter 16 is configured to emit a heartbeat message to be received by each remote receiver unit 18. When the remote receiver unit 18 receives the message, it will indicate that the receiver unit is in range and an appropriate indicator light may activate on the receiver unit 18 to show that the unit 18 is in range and “on-line”.

As the system 10 of the present invention provides for information to be broadcast to recipients across a wide population, it is imperative that such a system is not open to unauthorised use and for disseminating incorrect information that could compromise the safety of the population. Receiver Units 18 are designed to be inexpensive, and mass-produced and receiver units should be easy to obtain. However, a high level of security should be implemented across the system to avoid compromising the integrity of the system.

One way of addressing this is through the introduction of a VHF Radio Data System mechanism for transmitting signalling information to receiver units 18. As will become apparent below, such a system attempts to force any malicious users to use “a priori” techniques to gain access to the “the system”. This protects the signalling integrity from any human induced malicious attempts to create public havoc.

To achieve this, the system functions across four levels of security:

1. Trusted source

2. Temporal variance

3. Ciphering

4. Secret keys

Trusted Source

The receiver unit 18 must be confident that the data originates and is received from a secure source that is trusted by the receiver unit 18.

To achieve this, each transmitter 16 transmits “digital signatures” with each message frame. The “Digital signatures” are both static and dynamic and are embedded in multiple places within the message frame. Any incorrect “digital signature” will result in that message being rejected by the receiver unit 18.

Temporal Variance

Coordinated Universal Time (UTC) in the form of date (dd/mm/yy) and time (hh:mm) stamping is implemented in all messages transmitted from the transmitters 16 to the receiver units 18. All transmitters are Global Navigation Satellite System (GNSS) connected, thereby ensuring that they are synchronised to the same date and time.

Signalling information is temporally variant even though the payload content may not have altered. This ensures that the message is always dynamically scrambled. It is assumed that the date and time is known “a posteriori”. Regardless, this technique is used to ensure that the information is always scrambled differently regardless of payload variance.

Furthermore, the receiver units 18 will reject the current message if the most recently received date and time is earlier than the date and time received in the previous message. This decreases the threat of a message signal being copied (over the air) and then retransmitted later.

Ciphering

The contents of the signalling frames are scrambled with a bespoke algorithm and in conjunction with secret keys. The algorithm is designed for the requirements of the system i.e., simplex RF communication, processing resources, speed of calculation.

Secret Keys

As Simplex is used for communication between transmitters 16 and receiver units 18 any secret keys must be agreed upon prior to deployment in the system.

In accordance with an embodiment of the present invention, there are two secret keys employed. The secret keys operate concurrently with each other as opposed to sequentially and each key manipulates the signalling message frame in accordance with the ciphering algorithm. Each secret key is stored in the receiver unit 18 in a different area on the receiver unit assembly. Therefore, discovery of one secret key is insufficient to allow access to the message information.

It will be appreciated that system integrity is maintained through the combination of each of the above levels of security. Thus, in order to maliciously use the system, an external user must have knowledge of all digital signatures used, the ciphering/deciphering algorithm, the first secret key and the second secret key. To further increase the difficulty of hacking such a system, the time variance technique is employed.

It will be appreciated that the system of the present invention can be scaled for use across a wide range of user groups. Due to the use of a secured network of connected transmitters and receivers, emergency announcements can be sent to small settlements and villages as well as suburbs and heavily populated city centres, according to the needs of the emergency management agencies. The transmitters can be controlled remotely at a dedicated control centre or can be used as stand alone units where communication networks are not operational. The system is able to be used with a variety of third party systems to increase the information being used and analysed in a disaster setting.

Throughout the specification and claims the word “comprise” and its derivatives are intended to have an inclusive rather than exclusive meaning unless the contrary is expressly stated or the context requires otherwise. That is, the word “comprise” and its derivatives will be taken to indicate the inclusion of not only the listed components, steps or features that it directly references, but also other components, steps or features not specifically listed, unless the contrary is expressly stated or the context requires otherwise.

It will be appreciated by those skilled in the art that many modifications and variations may be made to the methods of the invention described herein without departing from the spirit and scope of the invention.