US3573379A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Communications system with frequency and time division techniques
Assignee: Bendix Corp
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Filing: 1969-03-03
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Granted: 1971-04-06
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Expires: 1989-03-03
Abstract
Abstract A communication system for a substantial number of subscribers is shown having random access capabilities without the requirement for the usual central exchange. The system uses a frequency division scheme for separating the several communication information channels. The individual subscriber units are interconnected as by means of one or more wires which are also connected to a master clock which continually generates time division digital information consisting of a plurality of pulses and unused time spaces (ones and zeros) including binary circuit code information and synchronizing pulses. A relatively limited band width is required for carrying this control information which is substantially displaced in frequency from the band containing the several communication information channels. These channels are generated by means of a frequency synthesizer in each of the subscriber units, each of which continually monitors the digital control information to determine whether its address is being called and the circuit code representing the channel of the incoming call. Similarly, outgoing calls are initiated by picking up a headset at the subscriber unit which causes an unused channel to be selected, inserting its circuit code into the digital stream and causing the frequency synthesizer in responding to this code to generate the corresponding carrier frequency. The audio information is then converted to single side band (or other) modulation of the particular carrier frequency signal.
Inventors
- 👤 Donald W Schmitz
- 👤 Benjamin Chandler Shaw
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 05:03
CPC Classifications
H; H04; H04J; H04J4/00; H04J1/00; H04J1/02; H04J1/06; H04Q; H04Q11/00; H04Q11/02
Claims Analysis
Total Claims: 21
Claim 1
Independent Claim
186 words
A communication system for providing communication among a plurality of individual subscriber units comprising: at least one interconnecting conductor connecting said units together, a master clock station connected to said conductor for continually providing time division digital information to said conductor, said information including a bit stream containing at least circuit code and synchronizing pulses; and said subscriber units containing means generating an address code, a frequency synthesizer capable of generating any of a plurality of communication channels and means connecting said bit stream to said synthesizer such that for receiving incoming calls said bit stream is continually monitored to determine whether the address code of said individual subscriber unit is being called and which of said channels the incoming call is using and for generating the carrier frequency corresponding to said channel, and for placing calls, said bit stream is monitored to find a circuit code indicating an unused channel, said channel is selected causing said circuit code to be changed to indicate that said channel is in use, and said frequency synthesizer is caused to generate a carrier frequency corresponding to said selected channel.
Claim 2
Dependent Claim
186 words
A communication system for providing communication among a plurality of individual subscriber units comprising: at least one interconnecting conductor connecting said units together, a master clock station connected to said conductor for continually providing time division digital information to said conductor, said information including a bit stream containing at least circuit code and synchronizing pulses; and said subscriber units containing means generating an address code, a frequency synthesizer capable of generating any of a plurality of communication channels and means connecting said bit stream to said synthesizer such that for receiving incoming calls said bit stream is continually monitored to determine whether the address code of said individual subscriber unit is being called and which of said channels the incoming call is using and for generating the carrier frequency corresponding to said channel, and for placing calls, said bit stream is monitored to find a circuit code indicating an unused channel, said channel is selected causing said circuit code to be changed to indicate that said channel is in use, and said frequency synthesizer is caused to generate a carrier frequency corresponding to said selected channel.
Claim 3
Dependent Claim
21 words
A communication system as set forth in claim 1 wherein said channels carry information in the form of single sideband modulation.
Claim 4
Dependent Claim
149 words
A communication system for providing communication among a plurality of individual subscriber units comprising: at least one interconnecting conductor connecting said units together; and frequency generating means in said subscriber units for generating carrier frequencies corresponding to any of a number of desired channels; a master clock connected to said conductor for continually generating and providing time division digital information to said conductor for continually generating and providing time division digital information to said subscriber units including at least a circuit code for selecting one of said channels; and means in each of said subscriber units for selecting an address code for a called subscriber unit, for continually monitoring said digital information to determine whether the individual unit''s address is being called, for identifying the circuit code of the incoming call, and for activating its frequency-generating means at the proper frequency corresponding to the frequency of the incoming call.
Claim 5
Dependent Claim
149 words
A communication system for providing communication among a plurality of individual subscriber units comprising: at least one interconnecting conductor connecting said units together; and frequency generating means in said subscriber units for generating carrier frequencies corresponding to any of a number of desired channels; a master clock connected to said conductor for continually generating and providing time division digital information to said conductor for continually generating and providing time division digital information to said subscriber units including at least a circuit code for selecting one of said channels; and means in each of said subscriber units for selecting an address code for a called subscriber unit, for continually monitoring said digital information to determine whether the individual unit''s address is being called, for identifying the circuit code of the incoming call, and for activating its frequency-generating means at the proper frequency corresponding to the frequency of the incoming call.
Claim 6
Dependent Claim
41 words
A communication system as set forth in claim 3 wherein each subscriber unit has a calling address code, and we when a call is placed from said unit said calling address code is added to said digital information on said conductor.
Claim 7
Dependent Claim
21 words
A communication system as set forth in claim 3 wherein said digital information includes synchronizing pulses and a calling address code.
Claim 8
Dependent Claim
25 words
A communication system as set forth in claim 3 wherein said interconnecting conductor includes a plurality of interconnecting wires all connected to said master clock.
Claim 9
Dependent Claim
23 words
A communication system as set forth in claim 3 wherein said channels each constitute single sideband modulation of one of said carrier frequencies.
Claim 10
Dependent Claim
101 words
A communication system for providing random access communication among a plurality of individual subscriber units comprising: at least one interconnecting communication path connecting said units together; means operatively connected to said communication path and continually operative over a first frequency range for generating coding information uniquely identifying any of a plurality of communication channels; monitoring means in each of said subscriber units continually receiving said coding information including Means capable of recognizing the code of any communication channel; and means in each of said subscriber units and operative over a second frequency a range for generating any of said communication channels.
Claim 11
Dependent Claim
101 words
A communication system for providing random access communication among a plurality of individual subscriber units comprising: at least one interconnecting communication path connecting said units together; means operatively connected to said communication path and continually operative over a first frequency range for generating coding information uniquely identifying any of a plurality of communication channels; monitoring means in each of said subscriber units continually receiving said coding information including Means capable of recognizing the code of any communication channel; and means in each of said subscriber units and operative over a second frequency a range for generating any of said communication channels.
Claim 12
Dependent Claim
53 words
A communication system as set forth in claim 8 wherein each of said subscriber units includes means for inserting a called address code into said coding information and said channel generating means operates in response to receiving coding information containing its address code to effectively connect its subscriber unit to said communication path.
Claim 13
Dependent Claim
41 words
A communication system as set forth in claim 8 wherein each of said subscriber units includes means monitoring said coding information to identify an unused channel, for selecting said channel and for causing said generating means to generate said unused channel.
Claim 14
Dependent Claim
19 words
A communication system as set forth in claim 8 wherein said communication path includes at least one electrical conductor.
Claim 15
Dependent Claim
19 words
A communication system as set forth in claim 8 wherein said communication channels constitute a plurality of carrier frequencies.
Claim 16
Dependent Claim
30 words
A communication system as set forth in claim 12 wherein said carrier frequencies are single sideband modulated and a band of unused frequencies is interposed between each of said channels.
Claim 17
Dependent Claim
37 words
A communication system as set forth in claim 8 wherein said communication path includes a substantial number of paralleled electrical conductors and means are provided for isolating any of said subscriber units which incur a short circuit.
Claim 18
Dependent Claim
29 words
A communication system as set forth in claim 8 wherein said coding information includes electrical pulses arranged in a digital word format and timing and synchronizing pulses are included.
Claim 19
Dependent Claim
167 words
For use with a system providing random access communication among a plurality of subscriber units connected to a common conductor and wherein a master clock continually provides digital control data on a time division basis to said conductor constituting a bit stream containing at least synchronizing pulses and circuit codes for identifying any of several communication channels: a subscriber unit including means coupling said unit to said conductor; means responsive to initiation of a call from said unit for selecting a vacant channel and for varying said bit stream to indicate that said channel is in use; means operative to insert a called address code into said bit stream; means continually monitoring said bit stream to determine whether the address code of said subscriber unit is being called, a frequency synthesizer capable of generating any of a plurality of carrier frequencies defining said communication channels; and means responsive to recognition of said vacant channel or of its called address and address code for actuating said frequency synthesizer.
Claim 20
Dependent Claim
167 words
For use with a system providing random access communication among a plurality of subscriber units connected to a common conductor and wherein a master clock continually provides digital control data on a time division basis to said conductor constituting a bit stream containing at least synchronizing pulses and circuit codes for identifying any of several communication channels: a subscriber unit including means coupling said unit to said conductor; means responsive to initiation of a call from said unit for selecting a vacant channel and for varying said bit stream to indicate that said channel is in use; means operative to insert a called address code into said bit stream; means continually monitoring said bit stream to determine whether the address code of said subscriber unit is being called, a frequency synthesizer capable of generating any of a plurality of carrier frequencies defining said communication channels; and means responsive to recognition of said vacant channel or of its called address and address code for actuating said frequency synthesizer.
Claim 21
Dependent Claim
155 words
A communication system as set forth in claim 16 wherein: said frequency synthesizer includes a stable oscillator; a first frequency dividing circuit for dividing the output of said stable oscillator into a lower frequency constituting a passband for said individual channels; a voltage controlled oscillator; a second frequency dividing circuit for dividing the frequency output of said voltage controlled oscillator by an integer; an adder circuit connected to said second frequency dividing circuit responsive to the signal representing the circuit code portion of said bit stream and for adding said signal to a signal representative of another number to produce a signal representing said it integer; a phase detector connected to receive the outputs of said first and second divider circuits and for producing an output voltage varying with the phase difference between the outputs of said divider circuits; and means filtering said phase detector output and connecting said filtered output to said voltage-controlled oscillator.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-04-05 | 1974-10-05 | 1975-04-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-04-05 | 1978-10-05 | 1979-04-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-04-05 | 1982-10-05 | 1983-04-06 | $7700.00 | Window Closed / Lapsed |