Abstract:
Apparatus, and an associated method, for annunciating a hazardous condition at an area encompassed by the annunciating system. The existence of an alert anomaly is annunciated. A receiver is coupled to receive indications of a warning representative of the alert anomaly. The receiver detects reception thereat of the indications of the warning. An annunciator is coupled to the receiver. The annunciator annunciates, in human perceptible form, the detection at the receiver of the indications of the warning representative of the alert anomaly. A transceiver is coupled to the receiver. The transceiver enables communication with similar apparatus to exchange settings, enable user control of remote devices, and exchange alert and non-alert conditions and audio.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    This invention relates to alert receivers and, more particularly to an alert receiver having an integrated linking function. 
         [0003]    2. Relevant Background 
         [0004]    Use of alert receivers has become increasing necessary and popular, both as a life saving measure from hazardous conditions and also as a simple means to obtain day-to-day weather conditions and forecasts. 
         [0005]    The National Weather Service (NWS) is an agency with the Department of Commerce&#39;s National Oceanic and Atmospheric Administration. Beginning in the late 1950s, the NWS, then the U.S. Weather Bureau, started developing a voice radio broadcast system to provide more frequent and specialized weather information to the general public and users with unique weather needs than was available from the commercial radio and television services. The service was eventually named NOAA Weather Radio (NWR). Operating frequencies are in the Federal Government&#39;s Very High Frequency (VHF) band between 162.400 and 162.550 MHz. 
         [0006]    A special feature of the NWR system that evolved in the 1960s was the transmission of a single tone at 1050 Hz prior to the broadcast of any message about a life or property-threatening event. This became known as the Warning Alarm Tone (WAT). Special receivers that are electronically switched on and receiving the broadcast signal, but the speaker is in a muted state, are made by several companies. When this type of radio detects the WAT, it automatically turns on the speaker allowing the alerting tone, then the alert message to be heard without the need for the owner/user to do anything. 
         [0007]    Starting in 1985, the NWS began experimenting with putting special digital codes at the beginning and end of any message about a life beginning and end of any message about a life or property-threatening event. The intent was to ultimately transmit a code with the initial broadcast of all NWR messages. The system evolved into what is known today as NWR Specific Area Message Encoding (NWR SAME). The general specifications are described briefly in the following sections. Complete and up-to-date specifications can be obtained by contacting the National Weather Service. 
         [0008]    The main purpose of the code created by NWR SAME is to provide enough information before and after the broadcast of a message so software routines can match preprogrammed user instructions. Its greatest value is to significantly improve the automatic selection and distribution of messages about events that threaten people and/or property. 
         [0009]    An NWR SAME transmitted data message consists of six possible elements in the following sequence: 
         [0010]    1) Preamble 
         [0011]    2) Header code 
         [0012]    3) Warning Alarm Tone/Attention Signal 
         [0013]    4) Voice Message 
         [0014]    5) Preamble 
         [0015]    6) End of Message 
         [0016]    The coded message is transmitted, using audio frequency shift keying (AFSK), on the audio channel of the VHF NWR transmitter system. It is transmitted at no less than 80% modulation (+/−4.0 kHz deviation minimum, +/−5 kHz deviation maximum). The coded message and voice program audio is transmitted using standard pre-emphasis for narrow band VHF FM of 6 dB per octave increasing slope from 300 Hz to 3 kHz applied to the modulator. 
         [0017]    The preamble and header code are transmitted three times with a one second pause (+/−5%) between each coded burst prior to the broadcast of the actual message. The End Of Message (EOM) consists of the preamble and EOM code transmitted three times with a one second pause (+/− 5 %) between each EOM burst. Each header and EOM data transmission consists of a string of eight 8-bit bytes with no start, stop, or parity bits. Bit and byte synchronization is attained by a preamble code at the beginning of each header code or EOM data transmission. Data transmissions are phase continuous at the bit boundary. 
         [0018]    One bit period equals 1920 microseconds (+/−1 microsecond). This equates to a data rate of 520.83 bits per second. A logic zero is 1562.5 Hz, a logic one is 2083.3 Hz. 
         [0019]    The first 16 bytes (prior to the header code and EOM) of the data transmission is a preamble with each byte having the same value of hexadecimal AB (8 bit byte [10101011]). For all bytes, the least significant bit (LSB) is sent first. The bytes following the preamble constitute the actual message data transmission. The message data (header) code is transmitted using ASCII characters as defined in ANSI X.3.4-1977 with the eighth (8th) bit always set to zero. 
         [0020]    The Warning Alarm Tone (WAT), if transmitted, is sent within one to three seconds following the third header code burst. The frequency of the WAT is 1050 Hz (+/−0.3%) for 8 to 10 seconds at no less than 80% modulation (+/−4.0 kHz deviation minimum, +/−5.0 kHz deviation maximum). 
         [0021]    If transmitted, the actual voiced message begins within three to five seconds following the last NWR SAME code burst or WAT, whichever is last. The voice audio ranges between 20% modulation (+/−1 kHz deviation) and 90% modulation (+/−4.5 kHz) with occasional lulls near zero and peaks as high as but not exceeding 100% modulation (+/−5 kHz deviation). The total length of the message should not exceed two minutes. 
         [0022]    NWS does occasionally send a continuous string of Preamble code, (Hex AB) or a continuous tone through its communications links to the NWR transmitters, for several seconds up to around one minute. This is done to align the program console, communications links, and transmitters for optimum system performance. 
         [0023]    In symbolic form, the message code format is: 
         [0024]    (Preamble) ZCZC−WXR−EEE−PSSCCC−PSSCCC+TTTT−JJJHHMM−LLLLLLLL− 
         [0025]    (one second pause) 
         [0026]    (Preamble) ZCZC−WXR−EEE−PSSCCC−PSSCCC+TTTT−JJJHHMM−LLLLLLLL− 
         [0027]    (one second pause) 
         [0028]    (Preamble) ZCZC−WXR−EEE−PSSCCC−PSSCCC+TTTT−JJJHHMM−LLLLLLLL− 
         [0029]    (one to three second pause) 
         [0030]    1050 Hz Warning Alarm Tone (WAT) for 8 to 10 seconds (if transmitted) Verbal/spoken oral text of message (if transmitted) 
         [0031]    (Preamble) NNNN
       (one second pause) (Preamble) NNNN   (one second pause)       
 
         [0034]    (Preamble) NNNN 
         [0035]    Symbol definitions: 
         [0036]    (Preamble) 
         [0037]    This is a consecutive string of bits (sixteen bytes of hexadecimal AB [8 bit byte 10101011]) sent to clear the system, set automatic gain controls, and set asynchronous decoder clocking cycles. The preamble must be transmitted before each header code and EOM code. 
         [0038]    “ZCZC−” 
         [0039]    This header code block is the identifier, sent as ASCII characters ZCZC to indicate the start of the ASCII header code data transmission. 
         [0040]    “-” (Dash) 
         [0041]    This “Dash” is sent following each type of code information block in the header except prior to the message valid time. 
         [0042]    “WXR-” 
         [0043]    This header code block identifies the message as a voice message from a 
         [0044]    NWR system transmitter. There are other identifiers used by EAS stations as defined in FCC rules Part 11. 
         [0045]    “EEE-” 
         [0046]    This header code block identifies the type of event and information contained in the verbal message, if a verbal message is sent. The event code may be sent with or without a WAT or verbal message as an alerting function only. It also may be sent as a control code for some NWR system control functions. 
         [0047]    “PSSCCC-” 
         [0048]    This header code block identifies the geographic area affected by the NWR SAME message. Each block of this coded information uniquely identifies a geographical area. A message may contain up to 31 blocks. 
         [0049]    This part of the geographical area header code block allows for subdividing the area defined by the “CCC” into smaller parts in the case of very large or uniquely shaped area, or because of widely varying height, climate, or other geographic features. If a “P”=0, it means the entire or unspecified are defined by “CCC” is affected. If the “P” equals a number other than zero, the areas are defined as follows:
       1=Northwest 1/9   2=North Central 1/9   3=Northeast 1/9   4=West Central 1/9   5=Central 1/9   6=East Central 1/9   7=Southwest 1/9   8=South Central 1/9   9=Southeast 1/9       
 
         [0059]    If the part is larger than 1/9 of the “CCC”, the following numbering convention is normally used depending on the desired size and/or orientation of the area such as from Northwest to Southeast, North to South, West to East, or 
         [0060]    Northeast to Southwest:
       1=Northwest ⅓ or ½ as appropriate   2=North ⅓ or ½ as appropriate   3=Northeast ⅓ or ½ as appropriate   4=West ⅓ or ½ as appropriate   5=Central 1/3   6=East ⅓ or ½ as appropriate     7 =Southwest ⅓ or ½ as appropriate   8=South ⅓ or ½ as appropriate   9=Southeast ⅓ or ½ as appropriate       
 
         [0070]    “SS” 
         [0071]    This part of the geographical area header code block is the number of the state as defined by the Federal Information Processing System (FIPS) number as described in the U.S. Department of Commerce in National Institute for Standards and Technology (NIST) publication #772. Special “SS” codes are assigned to those areas not defined by this publication such as the open waters of the Atlantic, Pacific, Gulf of Mexico, and Great Lakes. The most current list of special “SS” codes may be obtained from the NWS or the FCC upon request. 
         [0072]    “CCC” 
         [0073]    This part of the geographical header code block is a number normally assigned to each country in the United States by the FIPS. Special “CCC” codes are assigned to those areas not defined by the NIST publication #772. These include the open waters of the Atlantic, Pacific, Gulf of Mexico, and Great Lakes and to special alerting zones adjacent to and near unique storage or production facilities. A “CCC” of 000 applies to the entire state or area identified in the “SS” section of the code. The most current list of these special “CCC” codes may be obtained from either the NWS or the FCC upon request. 
         [0074]    Location codes transmitted over NOAA Weather Radio frequencies, but originated originally by security or communications centers at special hazardous materials storage or production facilities, my contain a combination of numbers, letters, and other characters. The authorized set is ASCII characters decimal  10 , and  13  and decimal  33  through decimal  127 . ASCII characters decimal  43  and  45  may not be part of the six character location code, but used only at the end of the block as shown previously in the symbolic form. The ASCII character decimal  42 , “*”, is reserved for use as a wild card only. These become special location codes containing a combination of geographic and instructional information to activate customized receivers, pre-stored text messages, and/or other special equipment. 
         [0075]    These codes will not be sent as part of NWS originated NWR SAME messages. NWR receivers with SAME decoders should not respond to such codes for NWS NWR or EAS purposes. Systems receiving NWR broadcasts and providing further redistribution may want to pass them along in any retransmission of the header code. Radio, television, or cable systems covered by FCC Rules Part 11 are not prohibited from using these codes in peripheral equipment or ancillary functions to basic EAS equipment to further enhance the safety of the public in cooperation with local government officials or facility managers. 
         [0076]    An NWR or EAS text standard over and above this special application of the location code is not defined under these specifications or EAS rules. A text standard could be developed using the basic NWR SAME/EAS protocol, but identified as a test message using a variation of the Originator code. The Originator Code in this section is reserved for voice messages only and decoders should reject any message that does not match this currently defined code set. 
         [0077]    Numbers from 900 to 999 are reserved for assignment to unique non-FIPS defined alerting areas adjacent to facilities that store or produce nuclear, chemical, and biological material. For the most current list of these areas, contact the NWS or FCC. 
         [0078]    “+TTTT−” 
         [0079]    This header code block identifies the purge time of the message expressed in a delta time from the issue time in 15 minute segments up to one hour. Then in 30 minute segments beyond one hour up to six hours; IE +0015−, +0030−, +0045−, +0100−, +0430−, +0600−. This delta time, when added to the issue time, specifies when the message is no longer valid and should be purged from the system, not to be used again. It is important to note that the valid or purge time of the message does not always equal the event expiration time. For most short-term events such as tornadoes and thunderstorms, the two times will most often be identical. For longer duration events, such as a hurricane or winter storm that may not end for many hours or days, the valid time in the code only applies to that message, and is not an indicator that the threat is over. 
         [0080]    Alert receivers are being purchased in every increasing numbers as a means for consumers to become alerted to severe weather and other conditions. The alerts provide time for the users to both seek adequate shelter from life-threatening weather and to protect property. Alert receivers are also commonly used to obtain weather forecasts to plan outdoor and other day-to-day personal activities. Units containing SAME decoders have removed the annoyance of alerts not in the geographical location of the receiver so usage has increased. 
         [0081]    Alert receivers are currently available both as portable units and as tabletop units to facilitate their use in different environments. In either of these roles, current receivers are limited in their effectiveness of alerting users. Due to practical and cost limitations, current designs can only alert users within a limited range of audibility from the alert receiver. Users can only tolerate a limited sound intensity when they are in close proximity to the device, so the far range of audibility of the device is limited by the nearby sound level (i.e. an arm&#39;s length from the user to the speaker or other audio output transducer). The range of audibility is decreased by objects, such as furniture or doors, between the alerting device and the user. The range of audibility may also be reduced by the poor sound reflectivity of surfaces caused by such home decorations as curtains and carpeting. The range of audibility may be lowered further by the physical layout of the user&#39;s premises. The size of the user&#39;s premises may also be larger than the maximum audible range of the alerting device. Some units such as Radio Shack models 12-249 and 12-250 allow connection of an external siren to increase the sound level, but doing so is beyond the skill of most users. The use of an external siren can also exacerbate the problems related to high sound intensity. User&#39;s are also unlikely to run wiring from the receiver to the siren due to the poor aesthetics of the wiring. 
         [0082]    Practical and aesthetic limitations limit the maximum size of the antenna that can be mounted on portable and tabletop weather alert receivers. This limits their receiver performance. To improve reception, some units such as Radio Shack models 12-247 and 12-250 allow external antennas to be connected. But again this is usually done only by skilled users. The minimum physical size of the antenna is dictated by the wavelength of the received signal (one wavelength is approximately 1.85 meters) and by the need for good reception. A sampling of antennas for receivers currently on the market included lengths of 20 to 22 inches (slightly longer than ¼ wavelength). Consequently, practical and aesthetic considerations limit where users are willing to locate their alert receivers. An example of a practical limit would be the desire of a user to have an alert receiver in the basement of their house for monitoring during a severe weather condition such as a tornado, but being unable to do so due to limited reception below ground level. An example of an aesthetic limit would be the desire to position an alert receiver in the living room, but being unwilling to do so due to the long antenna being perceived as unwieldy or ugly. For example, user&#39;s probably would be unlikely to place a receiver on a coffee table regardless of the improvement in having the device central to the user&#39;s living area. 
         [0083]    Some alert conditions, such as tornadoes or tsunamis, require immediate recognition by the user so they can adequately prepare for the event. Users are likely to place the receiver in a location such as a living room or bedroom, where it has the highest likelihood to be heard. Even when the alert siren can be heard at other locations, the user may not be in the vicinity of the receiver to immediately hear the alert broadcast or view the text display of SAME data to identify. Users with physical impairments to rapid movement such as the elderly, persons in wheelchairs, etc. cannot quickly reach the alert receiver. Persons with hearing impairments must move close to the location of the receiver to see the text display of the alert receiver in order to determine the type of alert. Thus some persons may lose valuable time that could be otherwise used to reach a safe location. While users could carry a portable device within their household to decrease the time to respond, this is highly inconvenient and a portable device may not provide adequate reception compared to another device with a superior antenna. A better solution would be to deploy multiple receivers in a household, but this introduces additional problems for users. If receivers are located too close to each other, the alert sounds may be too loud for the ears of users and there may be auditory distortion due to the user hearing the audio from multiple receivers with spatially caused delays. Subsequently, the user might be required to silence other alert receivers before being able to listen to a particular alert receiver. In addition, the user might need to quickly silence multiple units in order to not disturb others, such as sleeping children or babies. The user also has the initial chore of the programming and set up of multiple alert receivers. 
         [0084]    A discussion of the related art of which the inventor is aware, and its differences and distinctions from the present invention, is provided below. 
         [0085]    U.S. Pat. No. 7,050,784, Weather Radio with Channel Acquisition System, describes a method to automatically select a preferred channel of operation. Recent alert receivers such as the Radio Shack model 12-262 intelligently scan the entire alert frequency band to find the signal with best quality. This is determined by looking for the highest received signal strength, highest signal to noise ratio, or highest carrier to noise ratio. This is an excellent method for finding the optimal signal for the receiver under normal operation conditions, but provides no redundancy in the event of failure or degradation of the signal of the selected NWS transmitter. 
         [0086]    U.S. Pat. No. 7,130,600, Apparatus, and an associated method, for facilitating entry of location information at a weather band radio or other receiving station, describes a method for a SAME receiver to generate the 6 digit FIPS code using positional information input by the user of a receiver instead of directly entering the numerical FIPS code. While this can simplify setup of an alert receiver, any code, either positional or numeric, must be entered for each receiver at a premises increasing the likelihood of erroneous input. 
         [0087]    Publication US 2007/0194906, All Hazard Residential Warning System, describes use of a combination of mesh and community wide networks connected to the Internet to signal emergency conditions. The system is inferior to the current invention for multiple reasons including the likely inaccessibility of the Internet during some emergency conditions and the use of transmission frequencies that do not penetrate structures as readily as the NOAA alert signals. 
         [0088]    U.S. Pat. No. 6,744,351 describes a Central Radio Device And Associated Appliance. This system is inferior to the current invention in that the central device must be located at a location with sufficient signal for the alert receiver, uses appliances which are not battery backed up as remote signaling devices, and provides no redundancy in the event of the primary transmitter failing. 
         [0089]    Publication US 2003/0184436, Security System, describes a feature of a security system that can transmit voice and other audio of an alarm to other security systems within the same neighborhood. This feature only transfers audio and does not allow remote control of the systems. 
         [0090]    Publication US 2007/0100819, Method to decode a data string, describes a method to decode the multiple sets of received data from a NOAA Weather Radio transmission to improve the recovery of data from poor reception. This invention is inferior to the current invention since it only has the received data from one receiver to process. 
         [0091]    Publication US 2003/0179089, Emergency Warning System, describes a relay system where a system of sensors transmit an environmental condition to a receiver connected to a transmitter which relays the condition to multiple receivers in a secondary broadcast band. This system provides no redundancy for reception of the environmental condition transmissions. 
         [0092]    Publication US 2007/0013532 describes a combination thermostat and warning device that includes a receiver for broadcasts from the NWS. This system is inferior to the current invention since it does not provide redundancy for reception of the NWS broadcasts and does not provide voice audio or textual alert information to a plurality of devices. 
         [0093]    Publication US 2004/0235416 describes a method to facilitate setup of the FIPS code for selectively alerting for the geographical area of interest. This system is inferior to the current invention since it requires that the user set up a plurality of alert receivers individually. 
         [0094]    Publication US 2008/0227418 describes a method for monitoring multiple NOAA channels to acquire warning alert data. Although this solution is an improvement to most currently implemented alert receivers, this method is inferior to the current invention since it provides no positional diversity for signal reception. 
         [0095]    Publication US 2009/0002181, Disaster warning system, describes a system containing a weather radio, a tornado acoustic-signature detector combined with a smoke detector, and a carbon-monoxide detector. While this system would indeed provide a safety benefit to end users, it does not provide any capability for receiver diversity, single setup of a plurality of receivers, or a plurality of text or audio annunciators for distribution of alerts throughout the premises of a house or business. 
         [0096]    Furthermore, the above related art does not disclose the ability to assume remote control auxiliary devices of a similar nature as will be subsequently disclosed. 
       SUMMARY OF THE INVENTION 
       [0097]    This invention relates to alert receivers and, more particularly to an system of alert receivers having a linking function. 
         [0098]    The present invention advantageously provides, therefore, apparatus, and an associated method, for annunciating a hazardous condition at an area encompassed by the annunciating system. The existence of an alert anomaly is annunciated. A receiver is coupled to receive indications of a warning representative of the alert anomaly. The receiver detects reception thereat of the indications of the warning. An annunciator is coupled to the receiver. The annunciator annunciates, in human perceptible form, the detection at the receiver of the indications of the warning representative of the alert anomaly. A transceiver is coupled to the receiver. The transceiver enables communication with other similar apparatus to exchange settings, enable user control of remote devices, and exchange alert and non-alert conditions and audio. 
         [0099]    The foregoing and other features, utilities and advantages of the invention will be apparent from the following more particular description of a preferred embodiment of the invention as illustrated in the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0100]      FIG. 1  is a block diagram of a conventional alert device. 
           [0101]      FIG. 2  is a block diagram of the radio frequency receiver and decoder of an alert device. 
           [0102]      FIG. 3  is a block diagram of a linked alert device. 
           [0103]      FIG. 4  is a block diagram of a system of linked alert devices 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0104]    FIG.  1 —Conventional Alert Receiver 
         [0105]      FIG. 1  shows a functional alert system. The system monitors one or more alert frequencies and initiates an alert cycle when specified conditions occur. 
         [0106]    The alert receiver  100  encompasses the circuitry of the system. 
         [0107]    DC power supply  104  is conventional; it receives high voltage alternating current (AC) from the mains supply  102  and outputs low voltage direct current. 
         [0108]    Power supply  106  is conventional; it receives low voltage direct current power from the DC power supply  104  and supplies one or more direct current (DC) voltages to the rest of the alarm system. The distributed voltages may be regulated or unregulated depending on their ultimate use in the system. Backup battery  108  comprises one or more primary cell batteries and supplies power to the rest of the system when AC mains power is unavailable. 
         [0109]    Alternatively, DC power supply  104  and power supply  106  could be combined into a switching power supply that takes mains level AC and converts it to direct current for the rest of the alarm circuitry. 
         [0110]    Antenna  110  provides a means for obtaining a radio frequency signal in the NOAA weather band (162.400 MHz to 162.550 MHz) of sufficient strength to provide usable audio and data under all conditions. 
         [0111]    Alert receiver and decoder  112  is a standard narrow-band FM receiver used in conjunction with circuitry to filter and decode the audio frequency shift keying (AFSK) data containing weather alerts, decode and qualify the WAT tone, and digitally compress the audio of the alert message. The outputs of the alert receiver and decoder  112  connect to the control and timing logic  114  for determination of alert conditions. The alert receiver and decoder  114  outputs the audio of weather broadcasts and alerts to speaker  122  for listening under the control of the local user interface  116 . 
         [0112]    The control and timing logic  114  provides intelligence for the system and may consist of discrete timing and logic circuitry, but more typically is a microcontroller or microprocessor with external memory. The microcontroller or microprocessor processes alert states to determine if a change in the state of the system is required. If a change of state is needed, the microcontroller or microprocessor will change its internal status as well as changing the state of outputs, such as sirens, relays, or speakers. The microcontroller or microprocessor will also change the status presented to the user through the user interface  116 . User interface  116  may consist of a combination of light emitting diodes (LEDs), a liquid crystal display (LCD), a polymer light emitting diode display (PLED), a organic light emitting diode display (OLED), or any other type of display technology in addition to a means for the user to interact with the device using switches, keys, capacitive touch sensing, or some other input technology. The status is also presented to the user through audible output devices such as the siren  120 . Processing of inputs and changing of output states may occur synchronously or asynchronously with other events in the system. 
         [0113]    Siren driver  118  includes circuitry that provides a contact closure to connects one or more sirens  120  to an external power supply  124 . The siren  120  contain circuitry to generate and amplify an audio signal to a high audio level. 
         [0114]    The local user interface  116  provides functionality for a user to program the system, and/or to indicate the status of the system, including alerts. 
         [0115]    FIG.  2 —Alert Receiver 
         [0116]      FIG. 2  shows the elements of a functional receiver to detect and decode alert broadcasts. 
         [0117]    The weather alert receiver and decoder  200  consists of electronic circuitry to receive the SAME alert transmissions, demodulate the audio containing the verbal weather alert, and decode the transmitted data containing the weather alert in symbolic form. 
         [0118]    The antenna  202  provides a means for obtaining a radio frequency signal in the NOAA weather band (162.400 MHz to 162.550 MHz) of sufficient strength to provide usable audio and data under all conditions. A telescoping whip antenna is sufficient for most installations. However, for systems in locations at the fringe of the NWS station&#39;s reception area an larger external antenna such as a dipole or a vertical wire will be needed to increase the received signal to an acceptable level. 
         [0119]    The radio frequency receiver  204  is a standard narrow band VHF FM receiver designed to receive the 7 frequencies broadcast by the NWS. A wide variety of special integrated circuits for this function are available including the Numa Technologies NT2906. Operating parameters should match the signal specifications from the NWS. Received signal strength indication (RSSI) output  226  is coupled to a microcontroller to enable the microcontroller to intelligently select the optimum channel to receiver alert stations. 
         [0120]    The AFSK (audio frequency shift keying) filter  206  can be as simple as a standard bandpass filter implemented in analog circuitry. 
         [0121]    The audio compressor  208  is analog and/or digital circuitry to convert the audio into a digital representation that can be serially transmitted for remote listening. Standard compression techniques such as continuously variable delta modulation (CVSD) and adaptive differential pulse code modulation (ADPCM) give sufficient quality at low bit rates for the weather alert audio. The NWS has recently begun using computer-synthesized speech for the weather radio broadcasts. So care should be taken to choose a compression and bit rate that does not overly distort the lower quality speech signal. The compressed audio is passed via the compressed audio stream  216  to the device control/timing section for distribution throughout the system. The compressed audio stream  216  can be in a serial or parallel format. 
         [0122]    The WAT (Warning Alert Tone) decoder  210  is a standard tone decoder such as a National Semiconductor LM567. The WAT decoder is tuned to detect the 1050 Hz tone broadcast preceding the voice alert portion of a weather alert. The determination of a tone of sufficient duration to indicate an alert can be made by discrete circuitry or by the microcontroller or microprocessor of the system. The indication of a detected WAT tone is connected to the system through the WAT output  218 . 
         [0123]    The audio amplifier  212  is a standard amplifier for the audio band, 300 Hz to 3 kHz, such as the National Semiconductor LM386 or equivalent. The audio amplifier is connected through the speaker output  220  to a speaker for listening in the vicinity of the alert device. The audio amplifier  212 , including volume control and mute functions, is under the control of the alert devices microcontroller or microprocessor through the audio control  222  connection. 
         [0124]    The AFSK decoder  214  is a standard integrated circuit such as the EXAR 2211A specifically designed for FSK demodulation. The serial data stream is passed as a digital signal to the system microcontroller or microprocessor through the SAME data  224  connection. 
         [0125]    Note that the functions of the AFSK filter  206 , audio compressor  208 , WAT decoder  210 , and AFSK decoder  212  can be performed in software running on a high speed microcontroller, microprocessor, or digital signal processor (DSP). Examples of such parts are the Microchip Technology dsPIC30 and dsPIC33 digital signal controllers and Texas Instruments TMS320C55X digital signal processors. 
         [0126]    FIG.  3 .—Linked Alert Receiver 
         [0127]      FIG. 3  shows a functional linked alert receiver. The receiver monitors one or more alert frequencies and initiates an alert cycle when specified conditions occur. 
         [0128]    The alert receiver  300  encompasses the circuitry of the system. 
         [0129]    DC power supply  304  is conventional; it receives high voltage alternating current (AC) from the mains supply  302  and outputs low voltage direct current. 
         [0130]    Power supply  306  is conventional; it receives low voltage direct current power from the DC power supply  304  and supplies one or more direct current (DC) voltages to the rest of the alarm system. The distributed voltages may be regulated or unregulated depending on their ultimate use in the system. Backup battery  308  comprises one or more primary cell batteries and supplies power to the rest of the system when AC mains power is unavailable. 
         [0131]    Alternatively, DC power supply  304  and power supply  306  could be combined into a switching power supply that takes mains level AC and converts it to direct current for the rest of the alarm circuitry. 
         [0132]    Antenna  310  provides a means for obtaining a radio frequency signal in the NOAA weather band (162.400 MHz to 162.550 MHz) of sufficient strength to provide usable audio and data under all conditions. 
         [0133]    Alert receiver and decoder  312  is a standard narrow-band FM receiver used in conjunction with circuitry to filter and decode the audio frequency shift keying (AFSK) data containing weather alerts, decode and qualify the WAT tone, and digitally compress the audio of the alert message. The outputs of the alert receiver and decoder  312  connect to the control and timing logic  314  for determination of alert conditions. The alert receiver and decoder  316  outputs the audio of weather broadcasts and alerts to speaker  326  for listening under the control of the user interface  320   
         [0134]    The control and timing logic  314  provides intelligence for the system and may consist of discrete timing and logic circuitry, but more typically is a microcontroller or microprocessor with external memory. The microcontroller or microprocessor processes alert states to determine if a change in the state of the system is required. If a change of state is needed, the microcontroller or microprocessor will change its internal status as well as changing the state of outputs, such as sirens, relays, or speakers. The microcontroller or microprocessor will also change the status presented to the user through the user interface  320  User interface  320  may consist of a combination of light emitting diodes (LEDs), a liquid crystal display (LCD), a polymer light emitting diode display (PLED), a organic light emitting diode display (OLED), or any other type of display technology in addition to a means for the user to interact with the device using switches, keys, capacitive touch sensing, or some other input technology. The status is also presented to the user through audible output devices such as the siren  324 . Processing of inputs and changing of output states may occur synchronously or asynchronously with other events in the system. 
         [0135]    Siren driver  322  includes circuitry that provides a contact closure to connect one or more sirens  324  to an external power supply  328 . The siren  324  contain circuitry to generate and amplify an audio signal to a high audio level. 
         [0136]    The local user interface  320  provides functionality for a user to program the system, and/or to indicate the status of the system, including alerts. 
         [0137]    Link transceiver  312  provides connectivity between the alert receiver  300  and other compatible alert receivers. The link transceiver  312  is a conventional transceiver IC, such as the Texas Instruments CC2520 or Numa Technologies NT2906.Antenna  310  is a conventional antenna suitable for the transmit and receive frequencies. Antenna  310  may be a whip type antenna or instead be part of the PCB assembly of the link receiver  300 . Antenna  310  may also be combined with antenna  318 . Link transceiver  312  provides the alert receiver  300  with the functionality to communicate with other alert receivers to send and receive control commands, send and receive alert data, send and receive audio, send and receive receiver channel usage and assignment, and send and receive remote programming. 
         [0138]    FIG.  4 .—Block Diagram of Linked Alert Devices 
         [0139]      FIG. 4  shows a functional block diagram of a system of linked alert devices. 
         [0140]    System  400  comprises a first independent system of linked alert devices located at a first premises. The system  400  contains two linked alert devices,  404  and  408 . Alert device  404  receives alert broadcasts through antenna  402 . 
         [0141]    Similarly, alert device  408  receives alert broadcasts through antenna  410 . Alert device  404  transmits and receives linking transmissions through antenna  406 . Alert device  408  transmits and receives linking transmissions through antenna  412 . 
         [0142]    System  440  comprises a second independent system of linked alert devices located at a second premises. The system  440  contains two linked alert devices,  444  and  448 . Alert device  444  receives alert broadcasts through antenna  442 . Similarly, alert device  448  receives alert broadcasts through antenna  450 . Alert device  444  transmits and receives linking transmissions through antenna  446 . Alert device  448  transmits and receives linking transmissions through antenna  452 . 
         [0143]    System  400  and system  440  while fully functional as independent systems they may also link together briefly or longer term to send and receive alert data, send and receive audio, send and receive receiver channel usage and assignment, and send and receive programming information. 
         [0144]    An exemplary first National Weather Service station  480  is located in Dallas county, Texas and transmits weather and alert broadcasts through antenna  482 . A second exemplary National Weather Service station  484  is located in Tarrant county, Texas and transmits weather and alert broadcasts through antenna  486 . 
       Preferred Embodiment—Operation 
       [0145]    During the non-alert condition of the alert device  300 , the user interacts with the system through the local user interface  320 . To set up and initialize a first alert device  404  (an instance of  300 ), the user would insert the backup battery  308  and connect the DC adapter  304  to the device  300  and to AC power  302 . The alert device  300  would recognize that it had not been previously initialized and scan the weather band channels using radio frequency receiver  204  to determine which channel or channels are optimum for receiving alert broadcasts. Alert device  300  would subsequently present a choice to the user to select automatic or manual setup. 
         [0146]    Selecting automatic setup would initiate the alert device  400  to search for other alert devices in range. Alert device  400  would use its link transceiver  312  and antenna  310  to transmit messages requesting other units to respond. If no other units respond, then the user would be requested to enter or select a unique code for their premises. The code would then allow other units added to the system  400  to determine which alert devices should be linked. Alternately, the alert device  300  may select its own unique code that would be presented to the user using the user interface  320  for subsequent identification with other alert devices. 
         [0147]    If a second alert device  408  responded to the request message through link transceiver  312  and antenna  310 , the alert device  300  would present the user with messages on the user interface  320  to allow them to make further selections. For example, if alert device  408  was already initialized, alert device  404  would request data from alert device  408  to determine the county, state, and sub-county (FIPS) code or codes for the premises of system  400 . The alert device  404  would present the user with the choice of selecting all or a subset of the imported codes. For example, alert device  408  might be programmed to alert for the FIPS codes for both Tarrant and Dallas counties, but the user might select only Tarrant county for monitoring with alert device  404 . Further, the alert device  404  might also request data from alert device  408  for additional settings such as the alert types that are accepted, blocked, user interface settings, like volume, display contrast and backlighting intensity, etc. The net result is that device  404  would effectively clone the settings of device  408 . 
         [0148]    Subsequently, if the user determined that alert device  408  was in fact also their own device, the user would choose to link the units permanently thereby creating the linked system  400 . A consequence of creating a linked system  400  might be that each alert device  404  and  408  might allow the user to elect to decrease the sound level of the alert to each speaker  326  since each unit  404  and  408  would not be required to sound throughout the entire premises. 
         [0149]    The alert devices of linked system  400  may be located so that alert device  404  is only in reception range for Dallas County NWS station  480  while alert device  408  is only in reception range for Tarrant County NWS station  484 . The alert devices of linked system  400  may exchange their weather band reception information for use in non-alert and alert modes. It is anticipated that linked systems will be set up with devices in locations where one or more of the receivers are not on the same channel due to different reception at each device. Further, while it is anticipated that each alert device of linked system  400  will have adequate reception of at least one NWS station, the linked system  400  can operate with a minimum of at least one alert receiver  300  with reception of a single NWS station. For example, in linked system  400 , alert receiver  404  might be located on the first or second floor of a house and thus have adequate reception. However, alert receiver  408  may be, for usability reasons, located in the basement of the house and thus unable to receive any NWS station. In this example of a linked system  400 , alert receiver  408  allows the user to listen to audio from the NWS station received by alert receiver  404  by requesting the audio by means of one or more commands via the link transceiver  312  in each of the alert receivers  404  and  408 . 
         [0150]    Another benefit resulting from the linked system  400  would be the exchange of other information, such as the time and date. The user might update the time on alert device  404  and the time would be exchanged with alert device  408  and subsequently updated on alert device  408 . 
         [0151]    Another benefit resulting from the linked system  400  would be the exchange of test alert messages. NWS stations transmit weekly test messages unless there is a likelihood of an actual alert on the test day. In the linked system  400 , alert device  404  may receive the weekly test alert while alert device  408  does not. In this event, the linked system  400  may alert the user to the problem detected. Or alternately the linked system may reassign the alert device  408  to another channel such as the one in use by alert device  404 . In the event of the continued failure to receive alerts, alert device  408  may then be associated to alert device  404  as the channel to receive alert data and both alert and non-alert audio. 
         [0152]    If either the third alert device  444  or fourth alert device  448  responded and the second alert device  408  did not respond, the user would recognize that the alert devices were not located at her premises and would be presented with the choice to load the FIPS codes that are programmed into alert devices  444  or  448 . Other settings, such as radio channels, date, and time, may also be imported into alert device  404  at the choice of the user. Devices in linked systems  400  and  440  might also exchange and compare weekly test messages to insure the integrity of each system. 
         [0153]    Selecting manual setup would allow the user to select the sub-county, county, and state (FIPS) information or directly enter the FIPS code or codes that are desired to be monitored for this alert device  300 . The user would also scan for any other alert devices  300  in range of the device being set up. The user would then determine whether to link the alert device  300  with any other alert devices  300  found during the scan, thus creating the linked system  400 . 
         [0154]    Automatic setup of an alert device  300  in the linked system  400  also allows one or more alert devices  300  to be less than fully featured for the user interface  320 . For example, the linked system  400  would have at least one alert device with a text display that would allow the user to fully set up that device with appropriate FIPS codes. Subsequently, the user might set up other alert devices  300  with no display, by simply pressing a setup button on the less featured device. Such an alert devices, might consist of a user interface  320  with only multicolor light emitting diodes (LEDs) to indicate the alert level sent with the SAME message. Users would only able to determine the alert details by listening to the audio broadcasts of alerts. Some users might only use one of the less-featured alert devices  300  or several of the less-featured alert devices  300  in a linked system  400  since it is conceivable that they might have their systems initialized by someone else, either a relative or retail personnel at the store where they purchased their devices. 
         [0155]    When an alert event occurs, the signal is received by the antenna  202  of alert device  300  and demodulated into an audio signal by the radio frequency receiver  204 . The audio signal is filtered by the AFSK filter  206  to remove all audio frequencies outside of the passband of the AFSK signal. The AFSK decoder  214  demodulates the AFSK signal into a logic-level serial data stream of the NWS SAME data. 
         [0156]    The control/timing logic  314  decodes the data content of each of the three incoming SAME messages and buffers them in memory. If the control/timing logic  314  determines that the received messages are valid and without error, the control/timing logic  314  compares the geographical information in the received message with the geographic information entered by the user of the system, specifically the FIPS code and location within the user&#39;s county. If the locations match, the control/timing logic  314  reformats the weather alert information and sends the information to the user interface  320 . The user interface  320  indicates some portion of the data including the type of weather condition and the severity of the alert—statement, watch, or warning. Other information that can be displayed such as the duration of the event may or may not be supported by the user interface or may be elected by the user to be turned on or off. The control/timing logic  314  starts a timer based on the duration of the event. When the timer expires, the display of the weather event is discontinued on the user interface  320 . 
         [0157]    If the WAT tone is transmitted, the WAT decoder  210  detects the  1050  Hz tone and sends a signal on the WAT output  218  to the control/timing logic  314 . If the SAME messages have not been received or have been received with errors, the WAT tone may be used instead to initiate an alert condition. 
         [0158]    After the control/timing logic  314  has determined that the received messages are valid or a WAT tone has been qualified and initiated an audio alert, alert device  404  will relay alert and status information to other linked alert devices such as alert device  408 . A device  300  that receives SAME data that cannot be decoded due to poor reception will request alert and status information from other devices in its network or in range. It is anticipated that some users will only have a single unit  300  on their premises, but that those devices may link to other devices in range. An example of this would be an apartment or condominium dweller that is in close proximity to other residences. In this case, the devices  300  might exchange settings and data, but a user would have no control of other devices not on their own premises. 
         [0159]    If the control/timing logic  314  of alert device  404  has determined that a validated WAT signal has been detected, but no SAME message has been received, alert device would initiate an audio alert from the device. Alert device  404  would then initiate a request using link transceiver  312  and antenna  310  for SAME data from another linked alert device, in this instance alert device  408 . After the SAME data has been received, alert device  404  would then indicate the status level of the alert as well as the details of the alert using user interface  320 . 
         [0160]    If the alert device  404  has not received a valid SAME message or a validated WAT tone due to missing the transmission from signal errors or noise, the alert device  404  will remain in standby. However if another linked alert such as device  408  receives either the SAME message or validates the WAT tone, then alert device  408  will relay all available data to alert device  404  which will then indicate the alert condition. 
         [0161]    During or after one of the following conditions is met, the SAME data has been determined to be valid and without error or the WAT tone has been validated, the control/timing logic  314  turns on the audio amplifier  212  using the audio control  222  so the audio from the weather alert broadcast is output to the speaker  326 . If another linked device  408  cannot receive audio due to poor reception conditions or another cause, control/timing  314  can transmit the compressed audio from compressed audio stream  216  using link transceiver  312  and antenna  310 . 
         [0162]    After an alert audio cycle has been initiated by the alert devices  300  in the linked network  400 , the user would move to the immediate vicinity of one of the alert devices  300 . For example, the user might move to where they can interact with the user interface  320  of alert device  404 . The user would then press one key of a defined set of keys of the user interface  320  that would cause the alert device  404  to send a message to other alert devices, specifically  408 , in the linked network to silence their audio alert. Audio output would then be solely on unit  404 . Visual alerts on other alert devices in the linked network  400  would continue and users could listen to the audio on other devices, in this case alert device  408 , by pressing one key of a defined set of keys on the user interface  320  of alert device  408 . Alternatively, the user could respond to an alert condition using the user interface  320  of alert device  408 , thereby silencing alert device  404 . A user-selectable option might also be to allow the user to silence the alarm of an alert condition, but user interaction with the user interface  320  of an alert device  300  does not silence the alert audio on other alert devices  300  in the linked network  400 . As such, there might be another sequence of user interaction with the user interface  320  on an alert device  300  that silences all alert devices  300  in the alert network  400 . 
       Other Embodiments 
       [0163]    It is anticipated that other embodiments of the invention might be implemented to lessen or increase functionality, decrease cost, and/or decrease complexity. An example of decreased cost would be a system using multiple LEDs, each associated with a predefined or user-specified alert, as the indicators in the user interface instead of using a general-purpose liquid crystal display to display text detailing the current alert. This would decrease system cost. Many implementations may choose to only distribute text messages, without audio, to the remote user interfaces. Audio-only remote user interfaces may be used to distribute alerts where it is not desirable or physically feasible to mount a full-featured user interface. An example would be ceiling-mounted speakers in large rooms, stairwells, etc. where sound is needed, but user interaction and user viewing of the type of alert in text form is not. In a similar fashion, multicolor LEDs, discrete LEDs of different colors, or other indicators could be used to indicate specific weather conditions without audio. Such devices would prompt the user to move to the location of more fully featured alert devices to be informed of the details of the alert condition. 
         [0164]    It is also anticipated that another embodiment might consist of a reduced-functionality alert receiver incorporating a integrated circuit receiver such as the Silicon Laboratories Si4736 (AM/FM/Weather Band), Si4737 (AM/FM/WB), Si4738 (FM/WB), or Si4739 (FM/WB). These integrated circuits do not have the capability to decode the SAME data, but have the ability to detect the 1080 Hz tone. Thus alert receivers using these ICs do not decode the SAME data in an alert broadcast. However, the inclusion of the linking function in this embodiment would allow the alert data to be transmitted to the unit and displayed on a suitable user interface, such as an LCD for text or individual LEDs for specific alert events. The alert tone could be started after the SAME data was received and forwarded to the unit by a more capable device. This would also allow alerts to be masked on the reduced functionality devices based on the user preferences of the more capable devices. Alert receivers using the above or similar ICs can only receive one broadcast band at a time. If the user is listening to an AM or FM station the unit would otherwise miss an alert transmission, but the unit will receive a alert received message from another receiver and switch reception to the weather band so the user can hear the alert audio. A network of reduced functionality devices can also link and provide redundancy in the event that at least one unit receives an alert and another unit or units misses the alert. In all of these cases, the linking function also allows the control of remote devices when the user interacts with a unit. 
         [0165]    It is further anticipated that another embodiment would be constructed to interface with a personal computer. This configuration would allow the user to interact with the linked system using the more feature rich and graphical visual user interface of the computer. Alternatively, another device consisting of only a computer interface with a link transceiver  312  and antenna  310  would allow similar functionality. An anticipated benefit of allowing a personal computer to communicate with the alert system is that the computer could report signal reception back to the NWS through the Internet to provide substantive data of reception patterns. 
         [0166]    It is anticipated that linked systems with large numbers of alert devices might be used in locations such as offices, schools, hotels, etc. In such a system, one or more devices may serve as a master with the ability to change settings in other devices in the network, silence devices in unused rooms after an alert, test the network, set the time, etc. Additional functionality might be implemented to allow prerecorded messages to be played after the device has been triggered by an alert. Further, with the implementation of audio capability using the low power transceiver, the master may be used to provide real-time messages to the other alert receivers in the network. For example, after receiving a tornado alert message a user might verbalize a message such as “A tornado alert has been received, take shelter in the basement”. 
         [0167]    While the invention has been particularly shown and described with reference to a preferred embodiment thereof, it will be understood by those skills in the art that various other changes in the form and details may be made without departing from the spirit and scope of the invention.