DTMF Communication system
First Claim
1. A dual tone multiple frequency encoder system comprising:
- a keyboard providing data signals indicative of actuated keys;
a data store providing data signals indicative of data characters when addressed;
an encoder circuit coupled to receive sequential data signals from the keyboard and the data store and for each data signal to generate a dual tone multiple frequency signal indicative thereof;
an automatic number insertion circuit coupled to be operative upon receipt of a start signal to sequentially address the data store to generate a plurality of sequential data characters and to inhibit response of the encoder circuit to keyboard data signals only until after said plurality of sequential data characters from the data store have been generated and encoded as dual tone multiple frequency signals;
a start signal circuit coupled to generate a start signal in response to a keyboard key actuation.
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Accused Products
Abstract
A highly flexible and economical dual tone multiple frequency (DTMF) communication system includes a data input source such as a keyboard; a repertory dialer or electronic memory; an integratable digital encoder which includes a digital sine wave synthesizer; and a transmission unit such as a radio or a connection to a standard utility telephone system. The digital encoder provides a DTMF output signal at standard telephone frequencies in response to input data and includes a predial delay circuit which allows for dial tone delay or transmitter start up after receipt of data and before generation of an output signal, a two second delay circuit providing a two second output signal which may be utilized to prevent shut down between successive number entries and to lock out noise from a microphone or to a speaker and an automatic number insertion (ANI) circuit. When enabled, the automatic number insertion circuit automatically locks out a keyboard or other data source and transmits a 4 or 8 digit number supplied by a ROM before transmitting keyboard information. The ANI number may be used for automatic dialing, as a station identifier preceeding radio transmissions or as a code key enabling access to restricted information. Additional features provide in even further operator convenience.
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Citations
66 Claims
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1. A dual tone multiple frequency encoder system comprising:
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a keyboard providing data signals indicative of actuated keys; a data store providing data signals indicative of data characters when addressed; an encoder circuit coupled to receive sequential data signals from the keyboard and the data store and for each data signal to generate a dual tone multiple frequency signal indicative thereof; an automatic number insertion circuit coupled to be operative upon receipt of a start signal to sequentially address the data store to generate a plurality of sequential data characters and to inhibit response of the encoder circuit to keyboard data signals only until after said plurality of sequential data characters from the data store have been generated and encoded as dual tone multiple frequency signals; a start signal circuit coupled to generate a start signal in response to a keyboard key actuation. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31)
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32. A dual tone multiple frequency communication sytem comprising
a switch coupling the system to a telephone network; -
a microphone coupled to transmit voice frequency signals over a telephone network in response to audible voice frequency signals; a speaker coupled to generate audible voice frequency signals in response to voice frequency signals received over a telephone network; a keyboard providing data signals in response to the actuation of keys thereon; a digital encoder circuit coupled to receive the data signals from the keyboard and to transmit over a telephone network dual tone multiple frequency signals indicative of actuated keys, the digital encoder circuit including means for generating a first signal when a dual tone multiple frequency signal is being generated and means for generating a second signal when a dual tone multiple frequency singal is being generated and for a period of time thereafter; a muting circuit coupled to reduce the magnitude of audio signals from the speaker in response to a first signal; and a microphone circuit coupled to block signals from the microphone during the generation of a dual tone multiple frequency signal by the digital encoder circuit and for a period of time thereafter in response to the second signal. - View Dependent Claims (33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44)
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45. A dual tone multiple frequency communication system comprising:
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a radio transmitter coupled to transmit audio frequency signals applied to a signal input when enabled by application of an enable signal to an enable input; a digital encoder circuit generating dual tone multiple frequency signals in response to data input signals and generating a slow release signal that becomes active upon receipt of a data input signal and remains active for a period of time following a last data input signal, the digital encoder to control a data store and in response to a start signal; a data store coupled to provide data information to the digital encoder circuit under control of the automatic number insertion circuit; a microphone generating microphone signals indicative of audible signals received thereby; an actuatable microphone switch; and an interface circuit coupling dual tone multiple frequency signals to the transmitter signal input when generated by the digital encoder circuit, coupling microphone signals to the transmitter signal input in the absence of the slow release signal, applying an enable signal to the tramsmitter enable input in response to actuation of the microphone switch and in response to the slow release signal and generating a start signal in response to actuation of the microphone switch. - View Dependent Claims (46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57)
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58. A dual tone multiple frequency communication system comprising:
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a data unit coupled to provide a sequence of data signals to a digital encoder circuit in response to operator commands; and a digital encoder circuit coupled to digitally synthesize a dual tone multiple frequency signal corresponding to each data signal, the digital encoder circuit including means for generating an interdigit pulse signal that is coupled to the data unit and indicates completion of each dual tone multiple frequency signal. - View Dependent Claims (59, 60)
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61. A dual tone multiple frequency communication system comprising:
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means for providing data signals; and a digital encoder circuit coupled to receive the data signals and including a digital waveform synthesizer coupled to digitally synthesize dual tone sinewave signals at frequencies indicative of the data signals, each sinewave signal being synthesized for a minimum period of time notwithstanding earlier termination of a data signal for which a sinewave signal is generated. - View Dependent Claims (62, 63)
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64. A dual tone multiple frequency communication system comprising:
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a source of data signals; and a digital encoder circuit coupled to respond to a data signal from the source by digitally synthesizing dual tone multiple frequency sinewave signals indicative thereof, the digital encoder providing a selected time delay before commencing the synthesizing of a sinewave signal corresponding to a first of a sequence of data signals. - View Dependent Claims (65, 66)
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Specification