Abstract:
A method and apparatus for communicating audio messages uses a two-way radio. An output audio message is asynchronously transmitted by generating a first acoustic signal in an input device of the radio. A determination is made whether the first acoustic signal is a command. If the acoustic signal is a command, then a response is generated in an output device, and the command is processed. Otherwise, the first acoustic signal is stored in an output buffer and then later sent as an output audio message only when a communications channel is available. An input audio message is asynchronously received in a receiver of the radio, and then stored in an input buffer. A second acoustic signal is generated which causes the stored input audio message to be sent to the output device only if the second acoustic signal is a play command.

Description:
FIELD OF THE INVENTION 
   This invention relates generally to voice operated communication devices, and more particularly to two-way asynchronous transceivers. 
   BACKGROUND OF THE INVENTION 
   A number of radio communication modes are known. Simple two-way radio communications primarily use a simplex synchronous channel. This means that a single channel (frequency) is used, and a user can either send (speak) or receive (hear), but not both at the same time. In either case, whether the user is acting as a sender or a receiver, the sending and receiving of the signal occurred substantially simultaneously at both ends of the channel. Hence the communication is said to be synchronous. Common embodiments of such two-way synchronous radios are typically operated by depressing the “talk” button on the microphone. Of course, if both users depress their talk buttons at the same, then neither user hears anything. 
   A more modern version of such a two-way radio uses a duplex synchronous channel. In this case, both users can send and receive at the same time, and each user hears the other user&#39;s words as they are spoken. The most common form of this type of radio is the ubiquitous cellular telephone. 
   A characteristic of synchronous communication devices is that both the transmitter and receiver must be connected to the channel for the entire time that the communications occur. This is a problem in heavily populated urban areas where the number of available channels is much smaller than the number of potential users. In addition, cellular telephones requires a large number of buttons, and a display. This makes it difficult and distracting to operate the device. In addition, many users may desire to receive communications only at times selected by them, not at the times selected by senders. 
   Another problem with voice operated devices is to correctly recognize numbers, such as spoken telephone numbers, especially in the case that the identifier is in the form of large sequence of numbers, such as a security code or an account code much may well run twenty digits long. 
   One-way asynchronous communications devices have been available in the form of pagers. Typically, such devices can only passively receive and display simple textual messages such as telephone numbers of calling numbers. In most cases, a service provider is required to connect the pagers to standard telephone networks. 
   U.S. Pat. No. 4,860,359 issued to Eicher on Aug. 22, 1989 “Method of voice operated transmit control,” described a voice activated audio transmission system. There, an input signal was compared with an anti-VOX signal. As soon as a voice was detected, the voice signal was coupled for synchronous transmission. 
   U.S. Pat. No. 5,008,954 issued to Oppendahl on Apr. 16, 1991 “Voice-activated radio transceiver,” described a voice-activated transceiver that provided audio tones through earphones of the transceiver to announce the transition to and from transmit mode. By listening for the tones, the user was continuously apprised of the status of the transceiver. 
   U.S. Pat. No. 5,042,063 issued Sakanishi, et al. on Aug. 20, 1991 “Telephone apparatus with voice activated dialing function,” described a telephone in which a call could be placed by either dialing or speaking telephone numbers. 
   U.S. Pat. No. 5,584,052 issued to Gulau, et al. on Dec. 10, 1996 “Integrated microphone/pushbutton housing for voice activated cellular phone,” described a voice controlled vehicle accessory system responsive to voice commands and manual commands. Manual commands were entered via a single pushbutton having multiple functions depending upon an instantaneous state of a system controller. Predetermined voice commands were entered via a microphone. The types of accessories that could be coupled to the controller included the car throttle, audio system, climate system, and a cellular telephone. 
   U.S. Pat. No. 6,010,216 issued to Jesiek on Jan. 4, 2000 “‘Hear speak’ two way voice radio communications eyeglasses,” described a radio transceiver incorporated into eyeglasses. The transceiver included a voice activated switch to switch between receive and transmit mode. 
   U.S. Pat. No. 6,212,408 issued to Son, et al. on Apr. 3, 2001 “Voice command system and method,” described a system that allowed a communication device to accept voice commands from a user. The voice commands included commands to execute or dial key sequences or commands to control device functionality. Voice commands were received from a user of the communication device, indicating a command to be carried out by said communication device. Manual entry could be requested by the user in response to button activity or by a spoken command. 
   U.S. Pat. No. 6,236,969 issued to Ruppert, et al. on May 22, 2001 “Wearable telecommunications apparatus with voice/speech control features,” described a wearable communication apparatus in the form of a self-contained telephone headset. The headset could be activated by rotation of the mouthpiece into an operative position and deactivated by rotation out of that position. The base could be connected to a telephone network via a traditional landline, and communicate with the headset via an RF antenna. The headset included voice recognition capabilities that allowed the user to dial telephone numbers, access a memory of stored numbers, and direct certain headset functions simply by spoken commands. 
   Therefore, there is a need to provide two-way asynchronous data communications in a portable device that can be entirely controlled by spoken commands and identification phrases. 
   SUMMARY OF THE INVENTION 
   The invention provides a method and apparatus for communicating audio messages using a two-way radio. An output audio message is asynchronously transmitted by generating a first acoustic signal in an input device of the radio. A determination is made whether the first acoustic signal is a command. If the acoustic signal is a command, then a response is generated in an output device, and the command is processed. Otherwise, the first acoustic signal is stored in an output buffer and then sent as an output audio message only when a communications channel is available. 
   An input audio message is asynchronously received in a receiver of the radio, and then stored in an input buffer. A second acoustic signal is generated which causes the stored input audio message to be sent to the output device only if the second acoustic signal is a play command. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a view of a two-way asynchronous radio according to the invention; 
       FIG. 2  is a block diagram of the radio of  FIG. 1 ; 
       FIG. 3  is a flow diagram of transmitting audio messages by the radio of  FIG. 1 ; 
       FIG. 4  is a flow diagram of receiving audio messages by the radio of  FIG. 1 ; 
       FIG. 5  is a block diagram of a packet-switched network use with radios according to the invention; and 
       FIG. 6  is a graph of a probability lattice. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   System Components and Structure 
   External 
   As shown in  FIG. 1 , our two-way asynchronous radio  100  includes an antenna  101 , an indicator light, e.g., a LED  102 , a mechanical indicator (vibrator or ringer)  103 , a speaker  104 , an on/off switch  106  for a microphone  105 , and a volume control  107  all mounted on a housing  110 . The radio  100  can also include a multiple position select switch  109  to a select different modes of operation. 
   It should be noted, that the two-way radio according to the invention lacks the display and numerous buttons found in conventional two way communication devices such as cellular telephones. 
   Internal 
   As shown in  FIG. 2 , the housing  110  also contains a transmitter  201 , a receiver  202 , an output buffer  204 , a speech recognizer  205 , a speech synthesizer  206  all coupled to a controller  200 , and all operated by a battery supply  220 . The controller can be a microprocessor that maintains state  230  of the radio. The controller  200  also includes local memory  250  to store programs, and user supplied data, described in greater detail below. For example, the state can indicate whether a spoken command or message is expected as a next input acoustic signal. The radio can also be equipped with accelerometers (ACC)  208 . 
   System Operation 
   Transmitting 
   As shown in  FIG. 3  for the operation of transmitting  300  output audio messages  302 , a user speaks into the microphone  104  while pressing the switch  106  to generate a first acoustic signal  310 . The user can supply either a voice command  301  or spoken message  302  by speaking into the microphone  105 . These are translated to acoustic signals by the microphone  104 . Acoustic signals are acquired and processed as long as the switch remains pressed. Releasing the switch terminates signal acquisition. The speech recognizer  205  and the state  230  determine whether the acoustic signal is a command or a message. If the signal is a command  301 , then a response  303  to the command is generated by the speech synthesizer  206 , and played on the speaker  104 . 
   Alternatively, responses can be given via the light or mechanical indicator  102 – 103 . If the radio is equipped with the accelerometer  108 , then the user can move the radio  100  according to predetermined patterns to signal alternative commands. For example, vertical movements can indicate accord, and horizontal movements can mean cancellation. 
   Otherwise, if acoustic signal  310  is not a command, then the message  302  is stored in the output buffer  203 , and the transmitter  201  sends the stored message as an output audio message  304  when a communications channel is available. 
   Receiving 
   As shown in  FIG. 4  for the operation of receiving input audio messages  410 . The input messages  410  are received by the receiver  202  and stored in the input buffer  204  when the communications channel is available. When an input message is received and stored, the light or mechanical indicators  102 – 103  can be activated. In this case, as above, the user speaks into the microphone  104  while depressing the switch  106  to supply voice commands  401 , and an appropriate response is generated. The stored input message  410  is sent to the speaker  104  only if the command is a play command. 
   If the radio includes the select switch for different modes of operation, one mode may be “silent” mode where the light and mechanical indicators  102 – 103  are used for output signaling, and the accelerometers  208  is used for signaling commands, while the speaker plays messages at the lowest audible setting using the volume control  107 . Cancellation can also be indicated by rapidly depressing the switch  106  a predetermined number of times. 
   Network 
   As shown in  FIG. 5 , messages can be transmitted and received over communications channels via basestations  501  or a satellite  502 . In a practical embodiment, many users of the two-way radios  100  according to the invention concurrently communicate with each other using appropriate two-way wireless data communications technology, such as CDPD, GSM, GPRS, ReFLEX, 802.11b, and the like. The basestations  501  (or satellites) are connected to servers  510  operated by communications service providers. 
   The servers  510  act as a gateway, relaying messages to and from the radios  100 , and storing messages until they can be received by the radios. The servers  510  are interconnected by a conventional wide area network  520 , including the packet-switched Internet so that the radios  100  can communicate with Internet compatible devices. For example, in  FIG. 4 , the input message  410  can be sent to a PC or appliance  420 . 
   Commands 
   Because the radio  100  is primarily voice operated, a number of commands can be defined as indicated below in Table A. The commands and definitions are self explanatory. The commands can be associated with modifiers, such as “first,” “next,” “new,” “previous,” “last.” Note, these are only exemplary, other commands and modifiers can also be used. The key requirements is that the individual commands are intuitive, accurate, understandable, and distinguishable by the voice recognizer. 
                       TABLE A               Command   Definition                   Call   Send a message       Play   Play selected message       Repeat   Repeat last command       Delete   Deleted selected message       Cancel   Cancel last command, and return to previous state       Detail   Provide details on selected message       Send   Send message to selected address       Status   Provided status on radio, battery, memory, etc.       Help   Provide help information according to current state                    
Device Identification and Message Addresses
 
   The two-way asynchronous radio according to the invention can use the following identification scheme to address messages. Three types of identification spaces are defined, physical, logical, and name space. 
   Each radio has a unique physical identification that is “factory” assigned and unalterable. In practice, the useable physical identification space is very large, e.g., &gt;10 10 , or larger. 
   Associated with each physical identification is a user assigned logical identification. The logical identification is specified by a spoken phrase that includes a predetermined number of word “slots,” e.g., six slots. The words to fill the slots are selected from relatively small sets of unique words according to a vocabulary in a target language, e.g., there is a set of thirty-two word choices for each of the six slot in the phrase. Therefore, the number of different possible logical identifications is 32 6 . It should be understood, that larger identification spaces can be constructed by extending the size of the phrase or the size of the vocabulary, or both. 
   The user assigns the selected logical identification when the two-way radio is first used. At that time, the physical identification and logical identification can be stored in the memory  250  and transmitted to a common storage of a service provider for verification as to its uniqueness. 
   The order of the words in the phrase have a predetermined grammatical structure for the target language. For example, in the English language, the grammatical construction of the six words is:
         number:adjective:noun:verb:preposition:proper-noun       

   Moreover, to make the words easier to remember and select in a particular language, they can be further constrained. For example, the nouns in example Table B below are animals, the adjectives colors, the verbs are past-tense and motion related, and the proper-nouns are cities. 
   
     
       
             
             
             
             
             
             
             
             
           
         
             
                 
               TABLE B 
             
             
                 
                 
             
           
           
             
                 
               1 
               one 
               yellow 
               dogs 
               ran 
               over 
               Boston 
             
             
                 
               2 
               two 
               green 
               snakes 
               flew 
               under 
               Beijing 
             
             
                 
               3 
               three 
               white 
               horse 
               swam 
               around 
               Chicago 
             
             
                 
               4 
               four 
               black 
               pandas 
               drove 
               through 
               Tokyo 
             
             
                 
               . . . 
               . 
               . 
               . 
             
             
                 
                 
             
           
        
       
     
   
   The selected words in the phrase can also be mapped to numeric identifiers, for example, the phrase “four green dogs flew through Boston,” translates to “4.2.1.2.4.1.” Therefore, on a universal basis, the same unique identifier can have different expressions of word orders and grammars in different target languages. Thus, it is possible, for the same physical identification, to have expressions as different logical identifications (spoken phrases) for users in different countries. 
   Each user can further associate a local name, e.g. “John,” with each logical identification. This logical-name association is stored in a “phone-book” in the memory  250  of the controller. Then, the recognition of the logical phrases is only needed occasionally, e.g., when entering a logical names into the phonebook. Of course, different users can assign different local names to the same logical identification. 
   With this identification and addressing, a message can simply be sent by the command “Call John” which will asynchronously send a message to the two-way radio with a physical identification associated with the logical identification “4.2.1.2.4.1.” 
   This identification scheme has a number of advantages over prior art numeric identifiers such as telephone numbers. First, the phrases are much simpler to remember while still providing a large number of possible identification numbers with a fairly small number of words in the phrase. Also, the phrase is more resistant to error, either by the user, or by the speech recognizer  205 . It is well known that spoken telephone numbers are difficult to interpret correctly. 
   For example, a probability lattice can be used to correct or validate the output of the speech recognizer  205 . To determine the probability that a particular acoustic signal represents a particular phrase the speech recognizer  205  can generate a probability lattice. The probability lattice for the phrase represents a determination of the probabilities for each possible state path for the sequence of words in the phrase. The probability lattice contains a node for each possible state that the speech recognizer  205  can be in for each word in the phrase. Each node contains the accumulated probability that the words processed so far will result in the recognizer being in the state associated with that node. The sum of the probabilities in the nodes for a particular phrase indicates the likelihood that the words processed so far represent a prefix portion of the phrase. 
     FIG. 6  illustrates a probability lattice  600  for a phrase. The vertical axis  601  corresponds to a concatenation of the states of the speech recognizer  205  for the words that compose the phrase. Node  610  represents a final state for the phrase and contains the maximum probability of all the state paths that lead to that node. The bolded lines of  FIG. 6  represent the state path with the highest probability that ends at node  610 . In certain applications, it is helpful to identify a number of possible state paths in order of their probabilities. One well-known process for identifying such a state paths is the well Viterbi algorithm. 
   The output of the above probability analysis can be used in two ways. First, the most probably phrase can be mapped to its numeral equivalent, and a forward error correction techniques can be applied to correct any errors. Alternatively, the n most probably phrases can be further analyzed, and the phrase that is most self constant according to redundancy information encoded in the phrase is selected as the correct phrase. 
   This invention is described using specific terms and examples. It is to be understood that various other adaptations and modifications may be made within the spirit and scope of the invention. Therefore, it is the object of the appended claims to cover all such variations and modifications as come within the true spirit and scope of the invention.