US3783194A — Data modem having a fast turn-around time over di…

Claim 1

Independent Claim 328 words

A data communication system including data modems operating in a two wire/half duplex mode for data transmission in both directions over a direct distance dialed telephone line network; which network, upon random selection may include echo suppressors that require a finite turn-around time of approximately 150 milliseconds or longer rendering the network incapable of reversing direction of a data transfer until that finite time elapses unless such echo suppressors are first disabled by an echo suppressor disabling tone to remove high attenuation in the network and are thereafter maintained in a disabled state; the improvement comprising: means at said modems for transmitting data over said network in one direction only at a time over a given frequency bandwidth less than the total bandwidth of an ordinary telephone line; means associated with a data modem at either end of said network for applying only a unique tone of a given duration and within the data bandwidth for initially disabling all said echo suppressors in said network; residual network control signal generating means connected to said network and operative during time intervals when the network is free of data transmission in either direction, said generator when enabled emitting a signal selected from a frequency bandwidth free of frequency overlap with said given data frequency bandwidth and within the total telephone line bandwidth; means responsive to the cessation of the unique echo suppressor disabling tone for enabling said signal generating means after said echo suppressors are disabled for maintaining the echo suppressors disabled during the absence of data transfer in either direction over said network; means at a modem not receiving data for receiving from an external data terminal equipment a signal requesting a clearto-send answer signal prior to transmission of data in the given data direction for that modem over said network; and means connected to said signal receiving means for delivering, in an amount of time less than said finite time, a clear-tosend signal to said data terminal equipment.

Claim 2

Dependent Claim 328 words

A data communication system including data modems operating in a two wire/half duplex mode for data transmission in both directions over a direct distance dialed telephone line network; which network, upon random selection may include echo suppressors that require a finite turn-around time of approximately 150 milliseconds or longer rendering the network incapable of reversing direction of a data transfer until that finite time elapses unless such echo suppressors are first disabled by an echo suppressor disabling tone to remove high attenuation in the network and are thereafter maintained in a disabled state; the improvement comprising: means at said modems for transmitting data over said network in one direction only at a time over a given frequency bandwidth less than the total bandwidth of an ordinary telephone line; means associated with a data modem at either end of said network for applying only a unique tone of a given duration and within the data bandwidth for initially disabling all said echo suppressors in said network; residual network control signal generating means connected to said network and operative during time intervals when the network is free of data transmission in either direction, said generator when enabled emitting a signal selected from a frequency bandwidth free of frequency overlap with said given data frequency bandwidth and within the total telephone line bandwidth; means responsive to the cessation of the unique echo suppressor disabling tone for enabling said signal generating means after said echo suppressors are disabled for maintaining the echo suppressors disabled during the absence of data transfer in either direction over said network; means at a modem not receiving data for receiving from an external data terminal equipment a signal requesting a clearto-send answer signal prior to transmission of data in the given data direction for that modem over said network; and means connected to said signal receiving means for delivering, in an amount of time less than said finite time, a clear-tosend signal to said data terminal equipment.

Claim 3

Dependent Claim 45 words

An improvement in accordance with claim 1 and wherein said clear-to-send signal delivering means further comprises: a signal delay means connected to receive said request-to-send signal and characterized by having a signal delay time of one-third or less than the amount of said finite time.

Claim 4

Dependent Claim 38 words

An improvement in accordance with claim 2 wherein said signal delay means further comprises a delay circuit delaying the request-to-send signal for about 10 to 50 milliseconds and thereafter returning the clear-to-send signal to said data terminal equipment.

Claim 5

Dependent Claim 28 words

A system in accordance with claim 2 wherein said signal delay means is a variable delay characterized by a delay time ranging from about 10 to 50 milliseconds.

Claim 6

Dependent Claim 46 words

An improvement in aCcordance with claim 1 wherein: said transmitting means further comprises a data modulator in at least one of said modems, said modulator having a carrier modulated with all data to be transmitted, which data is the only data received by a receiving modem.

Claim 7

Dependent Claim 48 words

An improvement as defined by claim 5 wherein said control signal emitted by said generating means is applied only to said direct distance dialed network, said receiving modem receives only said data modulated carrier and is free of any receiving equipment operative in response to said control signal.

Claim 8

Dependent Claim 22 words

An improvement in accordance with claim 1 wherein: control signal generating means is included in at least one of said data modems.

Claim 9

Dependent Claim 28 words

An improvement in accordance with claim 7 wherein said control signal is emitted continuously after said echo suppressor disabling means originally disables all echo suppressors in said network.

Claim 10

Dependent Claim 142 words

A system in accordance with claim 5 wherein said echo suppressors, once disabled, remain disabled unless signal energy is absent from said direct distance dialed network for a predetermined time; said improvement further comprising: means enabling said request-to-send signal to be maintained as true level throughout data transmission by said data transmitting means and as a false level at other times; means enabling said signal generating means immediately after said echo suppressors are disabled; and control means either maintaining said signal generating means enabled continuously during the time the request-to-send signal is true or in the alternative maintaining said signal generating means enabled only when said request-to-send signal is in a false condition whereby the signal energy from said transmitting means represents energy on the network to keep said echo suppressors disabled during the time that said signal generating means is disabled.

Claim 11

Dependent Claim 267 words

A data communication system including data modems operating in a two wire/half duplex mode for data transmission in both directions over a direct distance dialed telephone line network; which network, upon random selection may include echo suppressors that require a finite turn-around time of approximately 150 milliseconds rendering the network incapable of reversing direction of a data transfer until that finite time elapses unless such echo suppressors are disabled by an echo suppressor disabling tone to remove high attenuation from the network; the improvement comprising: means for transmitting data over said network in one direction only at a time over a given frequency band less than the total bandwidth of an ordinary telephone line; control signal generating means connected to said network and responsive to the cessation of the echo suppressor disabling tone for passing a network control signal over said network after cessation of the suppressor disabling tone and during time intervals when the network is free of data transmission in either direction, said signal characterized in that it is selected from a frequency band free of frequency overlap with said given data frequency band and within the total telephone line bandwidth and it is unintelligible to any modem receiver; means at a modem not receiving data for receiving from an external data terminal equipment a signal requesting a clear-to-send answer signal prior to transmission of data in the given data direction for that modem over said network; and means connected to said signal receiving means for delivering, in an amount of time less than said finite time, a clear-to-send signal to said data terminal equipment.

Claim 12

Dependent Claim 267 words

A data communication system including data modems operating in a two wire/half duplex mode for data transmission in both directions over a direct distance dialed telephone line network; which network, upon random selection may include echo suppressors that require a finite turn-around time of approximately 150 milliseconds rendering the network incapable of reversing direction of a data transfer until that finite time elapses unless such echo suppressors are disabled by an echo suppressor disabling tone to remove high attenuation from the network; the improvement comprising: means for transmitting data over said network in one direction only at a time over a given frequency band less than the total bandwidth of an ordinary telephone line; control signal generating means connected to said network and responsive to the cessation of the echo suppressor disabling tone for passing a network control signal over said network after cessation of the suppressor disabling tone and during time intervals when the network is free of data transmission in either direction, said signal characterized in that it is selected from a frequency band free of frequency overlap with said given data frequency band and within the total telephone line bandwidth and it is unintelligible to any modem receiver; means at a modem not receiving data for receiving from an external data terminal equipment a signal requesting a clear-to-send answer signal prior to transmission of data in the given data direction for that modem over said network; and means connected to said signal receiving means for delivering, in an amount of time less than said finite time, a clear-to-send signal to said data terminal equipment.

Claim 13

Dependent Claim 45 words

An improvement in accordance with claim 10 and wherein said clear-to-send signal delivering means further comprises: a signal delay means connected to receive said request-to-send signal and characterized by having a signal delay time of one-third or less than the amount of said finite time.

Claim 14

Dependent Claim 38 words

An improvement in accordance with claim 11 wherein said signal delay means further comprises a delaY circuit delaying the request-to-send signal for about 10 to 50 milliseconds and thereafter returning the clear-to-send signal to said data terminal equipment.

Claim 15

Dependent Claim 28 words

A system in accordance with claim 11 wherein said signal delay means is a variable delay characterized by a delay time ranging from about 10 to 50 milliseconds.

Claim 16

Dependent Claim 46 words

An improvement in accordance with claim 10 wherein: said transmitting means further comprises a data modulator in at least one of said modems, said modulator having a carrier modulated with all data to be transmitted, which data is the only data received by a receiving modem.

Claim 17

Dependent Claim 48 words

An improvement as defined by claim 5 wherein said control signal emitted by said generating means is applied only to said direct distance dialed network, said receiving modem receives only said data modulated carrier and is free of any receiving equipment operative in response to said control signal.

Claim 18

Dependent Claim 22 words

An improvement in accordance with claim 10 wherein: control signal generating means is included in at least one of said data modems.

Claim 19

Dependent Claim 32 words

An improvement in accordance with claim 7 wherein said control signal is emitted immediately and continuously after cessation of said echo suppressor disabling tone has disabled all echo suppressors in said network.

Claim 20

Dependent Claim 147 words

A system in accordance with claim 14 wherein said echo suppressors, once disabled, remain disabled unless signal energy is absent from said direct distance dialed network for a predetermined time; said improvement further comprising: means enabling said request-to-send signal to be maintained as true level throughout data transmission by said data transmitting means and as a false level at other times; means enabling said control signal generating means immediately after said echo suppressors are disabled; and control means either maintaining said control signal generating means enabled continuously during the time the request-to-send signal is true or in the alternative maintaining said control signal generating means enabled only when said request-to-send signal is in a false condition whereby the signal energy from said data transmitting means represents energy on the network to keep said echo suppressors disabled during the time that said control signal generating means is disabled.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1976-12-31	1977-07-02	1978-01-01	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1980-12-31	1981-07-02	1982-01-01	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	1984-12-31	1985-07-02	1986-01-01	$7700.00	Window Closed / Lapsed

Data modem having a fast turn-around time over direct distance dialed networks

Abstract

Inventors

Bibliographic Details

Claims Analysis

References Cited (Backward Citations)

USPTO Annuity & Maintenance Windows

Assigned Categories & Tags

Assign Category Tag