Asynchronous communications system

Claim 2

An asynchronous communication system comprising a plurality of subscriber''s stations, a plurality of trunk stations distributed in a multiplicity of subareas to control said subscriber''s stations, which subareas are divisions of an area, and a central station to control all the trunk stations in said area; each of said subscriber''s stations comprising transmission means for generating an F-T matrix address including a plurality of pulses modulating a plurality of radio frequency carriers respectively in predetermined time positions assigned to each of a plurality of subscriber''s stations each time one of the pulses of pulse train constituting informations obtained by digitally modulating speech and signaling informations to be transmitted is generated, which time positions are a combination of time slots obtained by sequentially and equally dividing some constant interval of time and which radio frequency carriers are a combination chosen out of a group of radio frequencies obtained by dividing the available radio communication band width, whereby to a nearby trunk station are transmitted F-T matrix address radio pulses which are constituted by allotting a plurality of frequencies particular to said subscriber''s stations to said plurality of pulses, and meAns which receives address radio pulses of the same type transmitted from a nearby trunk station decodes said address radio pulses to convert them into a pulse train constituting speech and signaling informations and demodulates said pulse train to finally reproduce original information; each of said trunk stations comprising means which receives the F-T matrix address radio pulses transmitted by a plurality of calling subscribers and called subscribers located within each of said subareas and decodes said radio pulses to convert them into a plurality of pulse trains constituting speech and signaling information corresponding to a plurality of subscriber''s stations, means which digitally demodulates said pulse trains to reproduce a group of original informations, selects corresponding to each said group of informations a particular one of outgoing lines as instructed by said central station among trunk lines and transfers each of said group of informations to said central station through said outgoing line, means which receives a plurality of informations from calling subscribers and called subscribers in said subareas to be sent from said central station through incoming lines of said trunk lines and digitally modulates said informations to convert them into information pulse trains, and means which applies the pulse trains constituting informations respectively to subscriber terminals selected by the command of said central station and transmits F-T matrix address radio pulses corresponding to the subscriber''s identification number each time information constituting pulses are generated; said central station comprising means which receives subscribers'' speech and signaling informations from said trunk stations to establish talking paths by switching the connection of connecting network by means of a central control operating on a stored program principle, means which seizes the trunk lines of each trunk station registered in a memory of said central control, detects with respect to each trunk station the number of frequencies constituting respectively the addresses of subscribers and monitors the S/N ratio per each trunk station, means which blocks trunk lines other than a predetermined number of trunk lines with the aid of the S/N ratio monitor means so as to render the S/N value of each trunk station larger than a predetermined one, and means which receives reswitching demand signals generated by subscribers'' stations that detect the deterioration in S/N ratio as the result of their movement from one subarea to another, and controls the alteration of trunk stations and the switch-over of talking paths by means of searching and seizing other trunk stations which can receive radio signals transmitted from said subscribers'' stations.

Claim 3

An asynchronous communication system as defined in claim 1, in which each of said trunk stations includes digital modulators for converting the information signals delivered from digital modulators for converting the information signals delivered from respective incoming lines of a plurality of trunk line pairs coming from said central station into a group of information constituting pulse trains, respectively; a connecting network for connecting the output terminals of said digital modulator to transmitting terminals corresponding to a plurality of said subscriber''s stations, a radio transmitter for direct communication with said subscriber''s stations, including an address constituting network for providing each of said information constituting pulses appearing respectively at the output terminals of said connecting network with F-T matrix address radio pulses to be transmitted to the respective subscriber''s station, which radio pulses are generated only when each of said information constituting pulse occurs at said output terminal respectively; a radio receiver for direct communication with said subscriber''s stations, including an address separating network for deriving from the F-T mAtrix address radio pulses transmitted from said subscriber''s stations, the group of information constituting pulses corresponding respectively to said subscriber''s stations; a plurality of digital demodulators, each of which is connected with the respective outgoing lines of a plurality of trunk line pairs leading to said central station for converting groups of information constituting pulses delivered from said address separating network into groups of speech and signaling informations; a connecting network for connecting the outputs of said address separating network which are the receiving terminals corresponding to said subscriber''s stations to the input terminals of said digital demodulators; means for receiving digital control informations including instructions for connection, disconnection and subscriber scanning, each instruction being delivered from said central station; a subscriber scanning means for scanning said receiving terminals corresponding to said subscriber''s stations in accordance with said instruction for subscriber scanning to discriminate subscribers being in one of the ''''off-hook'''', ''''on-hook'''' and reswitching demand conditions; means for sending to said central station signals representative of said subscribers'' conditions; a connecting network control for connecting and disconnecting said connecting networks in accordance respectively with said connecting and disconnecting instruction from said central station; and a signal control circuit for sending dial tones to subscribers in accordance with instructions from said central station.

Claim 4

An asynchronous communication system as defined in claim 1, in which said central station includes a central control consisting of a memory comprising a program store for accommodating controlling functions, a call store for storing the informations on talking subscribers and an address store for storing relationships between a subscriber number and a F-T matrix address assigned to each of said subscriber''s stations and of a processing means comprising an instruction register, a memory register and a sequencer; a buffer register serving as a buffer means between the control lines of said trunk stations and said central control which buffer register comprises means connected with pairs of the incoming and outgoing control lines of said trunk stations to store subscribers'' signaling informations for service demand, subscriber terminal informations and trunk station numbers sent from said trunk stations upon receipt thereof through said incoming control lines and which successively transfers said informations sent from said trunk stations to said central control in accordance with buffer register scanning instructions sent from said central control and means responsive to dialing operation in accordance with instructions from said central control for transferring the instructions for connection including subscribers'' terminal numbers and trunk numbers to be connected together between said trunk stations under direct communication with calling subscriber and called subscriber through said outgoing control lines; a signal generator connected with said central control through control lines, which signal generator generates instructions for delivering signals representing called subscribers'' numbers in accordance with instructions from said central control when the service demands from said central station are dial informations, creates busy tones in accordance with instructions from said central control if the trunk station and trunks for called subscribers concerned are busy, produces ringing tones in accordance with ringing instructions for the called subscribers sent from said central control if the trunk station and the trunks for the called subscribers are idle while it generates ring-back tones for associated calling subscribers, and provides signals for confirmation of talking conditions for the calling subscribers upon termination of talking in accordance with instructions From said central control, a signal receiver which receives return signals from said subscriber stations in response to the instruction signals from said central control in the form of information signals representative of the called subscribers'' numbers transmitted from the calling subscribers during dialing operation and response signals returned from the called subscribers'' stations and which in turn transfers these signal informations to said central control; and a connecting network connected with plural pairs of trunk lines, each pair consisting of an incoming trunk line and an outgoing trunk line, connected with said trunk stations which connecting sends or receives voice informations and signal informations to or from said trunk stations through said trunk lines, establishes connections between particular outgoing trunk lines of the trunk stations under direct communication with the calling subscribers or the called subscribers and the output terminals of said signal generators and between the incoming trunk lines of the trunk stations under direct communication with the calling subscribers or the called subscribers and the input terminals of said signal receiver in accordance with the control instructions of said central control at the stage of establishing the connections of trunks between the calling subscribers and called subscribers, and connects the incoming trunk lines of the trunk stations under direct communication with the calling subscribers with the outgoing trunk lines of the trunk stations under direct communication with the called subscribers and the outgoing trunk lines of the trunk stations under direct communication with the calling subscribers with the incoming trunk lines of the trunk stations under direct communication with the called subscribers, thereby to make possible communications between the calling subscribers and the called subscribers.

Claim 5

An asynchronous communication system as defined in claim 1, in which each of said subscribers'' stations comprises an asynchronous three-level delta modulator which converts voice informations and signaling informations into a train of information constituting pulses constituted by positive, negative and zero pulses, each pulse being asynchronously spaced in time; an address modulator which generates a positive F-T matrix address and a negative F-T matrix address in response to positive and negative pulses of the information constituting pulses respectively, both addresses being particular to said subscriber stations, and which includes delay circuits for generating address constituting pulses only in predetermined time positions particular to each of said subscriber''s stations among a predetermined number of sequentially and equally divided time intervals only when any positive or negative pulse is generated from said delta modulator, radio frequency oscillators particular to each of said subscriber''s stations for providing exclusively in said particular time intervals the address constituting pulses with a predetermined number of frequencies particular to each of said subscriber''s stations selected among a plurality of frequencies, and a digital logic network for inverting the order of frequencies allotted to the output pulses from said delay circuits depending upon whether the information constituting pulses from said asynchronous three-level delta modulator are positive or negative; radio transmitter means which radio-transmits said F-T matrix address; radio receiver means which receives and amplifies the F-T matrix address radio pulses; an address demodulator which decodes the positive and negative F-T matrix addresses particular to each of said subscriber''s stations, and which includes filters particular to each of said subscriber''s stations for separating a plurality of address constituting frequencies, delay circuits for providing pulses obtained by detecting the outputs of said filters with appropriate delays corresponding to the intervals of pulses coNstituting the addresses particular to each of said subscriber''s stations with respect to the channels corresponding to the respective address constituting frequencies, a pair of digital coincidence circuits for receiving the outputs from delay circuits and decoding them as positive or negative information constituting pulses; and an asynchronous three-level delta demodulator for converting a train of information constituting pulses from said address demodulator into voice informations or control signal informations.

Claim 6

An asynchronous communication system as defined in claim 1, which controls connecting operations between calling subscriber''s station and called subscriber''s station by means of trunk controls provided in said trunk stations and a central control incorporated in said central station, each of said trunk controls comprising control means which detects the presence or absence of connecting instructions from the central station, control means which scans the subscriber receiving terminals by means of the subscriber scanning circuit in the case where there is no connecting instruction received from the central station and detects subscriber signal informations to transfer the informations to the central station, and control means responsive to any connecting instruction received from the central station for interrupting the scanning operation to cause the connecting network to establish the connections between the subscribers'' terminals in the trunk stations and the trunk lines; and said central control comprising control means which causes the buffer register to store the subscriber signal informations from the trunk stations to identify one of the signal informations consisting of dial-tone signals, response signals, dial termination signals and reswitching demand signals by scanning the stored information, control means which allots some of the trunk lines to a first trunk station that acknowledges the receipt of ''''off-hook'''' signals from calling subscribers to detect with respect to said first trunk station the S/N value from the address informations of subscribers so that in case where the S/N value detected is larger than a predetermined reference value first trunk station transmits to the calling subscribers'' commands for transmitting the informations containing the associated called subscribers'' numbers by means of said signal generator, control means which causes a signal receiver and a station number receiver to receive and store the informations containing the called subscribers'' numbers sent from the calling subscribers in response to said commands to detect called subscribers in accordance with the informations, control means which scans the buffer register containing the subscribers'' signal informations from said first trunk station to identify the called subscribers and to detect the connection condition thereof, control means which in case where the called subscribers are not busy detects the number of the address frequencies of the subscribers who are seizing the trunk lines between said central control and the trunk stations located near the called subscribers to compare one S/N value with another among the trunk stations and to select a second trunk station for which the S/N ratio under consideration assumes the largest value, control means which causes the selected second trunk station to transmit the ringing tone signals generated by said signal generator to the called subscriber and the first trunk station to transmit the ringback tone signals to the calling subscribers, control means which completes the establishment of talking paths between the calling and called subscribers in accordance with the responses from the called subscribers detected by means of said signal receiver, and control means which breaks the established talking paths between the calling and called subscribers in response to the ''''hook-on'''' operation of either one or both of the calling and called subscribers.

Claim 7

An asynchronouS communication system as defined in claim 3, wherein said central station further comprises memory means connected to said central control to store the addresses of subscribers'' stations in connection, counting means connected to said memory means to count the number of subscribers'' stations connected to each of said trunk stations using each of the frequency slots, decision means connected to said counting means to identify whether the respective counts or a processed value, such as a weighted sum or root-mean-square of said counts exceeds a predetermined value.

Claim 8

An asynchronous communication system as defined in claim 6, in which said central station further comprises means which scans the subscribers'' terminals of the trunk stations to confirm the talking condition, means which with the aid of said scanning means transmits scanning pulses through the associated trunk stations to the subscribers'' stations and then confirms the talking conditions of the subscribers by virtue of response pulses sent back from the subscribers'' stations in response to the scanning pulses, and means which records talking durations and performs accounts for charging by virtue of the response pulses from the subscribers'' stations.

Claim 9

An asynchronous communication system as defined in claim 4, wherein each of said subscribers'' stations further comprises a field intensity detection means connected to the output of said asynchronous delta demodulation means an an oscillator connected through gating means to the input of said asynchronous delta modulation means, said field intensity detection means including threshold means for generating a reswitching demand signal indicating that the received field intensity level is below a predetermined level, and said gating means being controlled by said reswitching demand of said field intensity detection means to transmit the output of said oscillator to said asynchronous delta modulation means.

Claim 10

An asynchronous communication system as defined in claim 3, wherein said central station further comprises a plurality of field intensity detention means, each of said field intensity detection means being connected to said trunk lines from said trunk stations through said connecting network, scanning means selectively connected to each of said field intensity detection means, and comparison means connected to said scanning means for identifying a trunk station with the highest field intensity.

Claim 11

An asynchronous communication system as defined in claim 4, wherein each of said subscribers'' stations further comprises a plurality of oscillators and a plurality of filters, each of said oscillators being connected to the input of said asynchronous three-level delta modulation means through gating means operated by subscribers'' ''''off-hook'''', dialing, reswitching demand and ''''on-hook'''' conditions, and each of said filters being connected to the output of said asynchronous three-level delta modulation means for extracting instruction signals from trunk stations.