US4042893A
Expired / Lapsed
US
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Method and apparatus for improving transmission line characteristics
Assignee: Siemens AG
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Filing: 1972-04-10
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Granted: 1977-08-16
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Expires: 1992-04-10
Abstract
Abstract A technique of reducing "crosstalk" in transmission lines for time multiplex pulse communication, by insertion of artificial compensating networks having an impedance varying with frequency in opposite sense as compared with the natural impedance of the line. The values of the elements of the network are determined by transmitting a pulse over the line and determining the distortion to that pulse.
Inventors
- 👤 Ernst Hofer
- 👤 Max Schlichte
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 05:24
CPC Classifications
H; H04; H04B; H04B3/00; H04B3/02; H04B3/32; H04B3/34; H04B3/04; H04B3/14; H04B3/143
Claims Analysis
Total Claims: 19
Claim 1
Independent Claim
132 words
A method for compensating a transmission line used for time multiplex transmissions, which transmits messages from different channels on a sampled basis in the form of time spaced pulses for each such channel, wherein the transmission line is shorter than the width of the pulses supplied thereto resulting from the time duration and the propogation speed of said pulses and wherein pulses of one channel can overlap to pulses of an adjoining channel due to the influence of skin effect, comprising the step of: reducing the frequency dependence of the impedance of said transmission line by connecting to said line at least one compensating network having an impedance which varies oppositely with frequency to the variations of the impedance of said transmission line caused by skin effect, but by the same amount.
Claim 2
Independent Claim
132 words
A method for compensating a transmission line used for time multiplex transmissions, which transmits messages from different channels on a sampled basis in the form of time spaced pulses for each such channel, wherein the transmission line is shorter than the width of the pulses supplied thereto resulting from the time duration and the propogation speed of said pulses and wherein pulses of one channel can overlap to pulses of an adjoining channel due to the influence of skin effect, comprising the step of: reducing the frequency dependence of the impedance of said transmission line by connecting to said line at least one compensating network having an impedance which varies oppositely with frequency to the variations of the impedance of said transmission line caused by skin effect, but by the same amount.
Claim 3
Dependent Claim
63 words
The method defined in claim 1, comprising the further steps of: determining the frequency dependent inherent attenuation curve of said transmission line by measuring the distortion of an electrical pulse of known waveform transmitted through the transmission line, and inserting into the transmission line a compensation network having a time constant sufficient to correct for to the measured distortion of the transmitted pulse.
Claim 4
Dependent Claim
117 words
The method defined in claim 2 wherein said determining step comprises: terminating the transmission line at the input terminal thereof in the characteristic impedance of said line and at its output terminals in a short circuit, applying a current pulse at the input terminals of the transmission line, measuring the voltage amplitude at said input terminals as a function of time to deterime the attenuation of a voltage pulse produced on said transmission line for transmission thereover and resulting from said current pulse and wherein said inserting step comprises: inserting into said transmission line a compensation network having a time constant corresponding to that of said transmission line, as determined by said measurement of said voltage amplitude.
Claim 5
Dependent Claim
90 words
The method defined in claim 3 wherein said measuring step comprises: measuring the voltage amplitude of the voltage pulse attenuation curve at selected times defining a plurality of time intervals, each said time interval corresponding to a segment of the attenuation curve, and determining the attenuation of the voltage pulse for each such segment of the attenuation curve to define a time constant of a corresponding one of a plurality of compensation networks and wherein said inserting step comprises: inserting a plurality of said compensation networks into said transmission line.
Claim 6
Dependent Claim
67 words
The method defined in claim 3 wherein a reflection from the end of said transmission line causes a reflected pulse to be present following termination of an applied pulse, the method further comprising: determining the electrical values of the element of a compensation network of a prescribed time constant by adjusting said element thereof to maximize the rate of decrease of the slope of the reflected pulse.
Claim 7
Dependent Claim
73 words
The method defined in claim 5 wherein the reflection from the end of said line causes a reflected pulse to be present following termination of the applied pulse wherein the elements of the compensation network include a capacitor and a resistor, the time constant of the network corresponding to the attenuation curve of the measured voltage pulse, and the values of the capacitor and resistor of the network being determined by the balancing.
Claim 8
Dependent Claim
69 words
The method defined in claim 1 wherein said compensating network is a parallel resistance-capacitance network and the time constant of said network is determined by the equation: R=√L/C when: R=the resistance value of the resistance portion of said network and the resistance of said transmission line caused by skin effect which are equal resistances, C=the capacitance of said network, L=the conductor of said transmission line caused by skin effect.
Claim 9
Dependent Claim
110 words
The method defined in claim 1 wherein the pulses are transmitted in a plurality of pulse trains on a single transmission line in accordance with a plurality of corresponding communication channels of successive time intervals of a time multiplex transmission system and comprising the further step of: transmitting at least one pulse of a pulse train corresponding to a given communication channel, measuring the amplitude of crosstalk voltage coupled into adjacent successive communication channels in response to the pulse transmission in the given communication channel and establishing the time constant of the compensation network in accordance with the decrease in amplitude of crosstalk voltage coupled into the successive communication channels.
Claim 10
Dependent Claim
71 words
The method defined in claim 8 comprising the further steps of: inserting a plurality of compensation networks in sequence into the transmission line, measuring, for each compensation network thus inserted, the amplitude of crosstalk voltage coupled into respectively adjacent successive communication channels and establishing the time constant of each such compensation network in accordance with the decrease in amplitude of the crosstalk voltage coupled into the respectively adjacent successive communication channels.
Claim 11
Dependent Claim
110 words
The method defined in claim 9, wherein said inserting step comprises: providing a parallel circuit of a resistor and a capacitor for each said compensation network, determining the electrical values of resistance and capacitance of each said compensation network in sequence by inserting a compensation network having adjustable relative values of resistance and capacitance into the transmission line and adjusting the values thereof to minimize the amplitude of crosstalk voltage coupled into the adjacent successive communication channels, and replacing the adjustable compensation network with a compensation network having elements of fixed electrical values as determined through balancing of the adjustable compensation network for each of the plurality of compensation networks.
Claim 12
Dependent Claim
115 words
In a transmission line for time multiplex transmissions wherein scanning samples of messages from different channels are transmitted in the form of time-spaced pulses, said line being shorter than the width of said pulses resulting from the time duration and speed of propogation of said pulses, said line being compensated to prevent interference between channels as a result of skin effect, the improvement comprising: at least one compensation network means connected to said line for reducing the frequency dependence of the impedance of said line, said network means having an impedance which varies oppositely with frequency to the variations in the impedance of said transmission line caused by skin effect, but by the same amount.
Claim 13
Dependent Claim
115 words
In a transmission line for time multiplex transmissions wherein scanning samples of messages from different channels are transmitted in the form of time-spaced pulses, said line being shorter than the width of said pulses resulting from the time duration and speed of propogation of said pulses, said line being compensated to prevent interference between channels as a result of skin effect, the improvement comprising: at least one compensation network means connected to said line for reducing the frequency dependence of the impedance of said line, said network means having an impedance which varies oppositely with frequency to the variations in the impedance of said transmission line caused by skin effect, but by the same amount.
Claim 14
Dependent Claim
59 words
The apparatus defined in claim 11, wherein said compensation network comprises a parallel circuit of a resistor and a capacitor and said resister and said capacitor of said compensation network have values which give to said compensation network a time constant corresponding to the time constant of the attenuation curve of an electrical pulse transmitted in said transmission line.
Claim 15
Dependent Claim
28 words
The apparatus defined in claim 12, wherein said resistor and said capacitor have values selected to effect a maximum attenuation of the electrical pulse in said transmission line.
Claim 16
Dependent Claim
59 words
The apparatus defined in claim 12 wherein said resistor and said capacitor are selected to have electrical values for minimizing the voltage amplitude of crosstalk voltage coupled into adjacent successive communication channels as a result of electrical pulse transmission in a preceding communication channel during time multiplex transmission in a plurality of communication channels over a single transmission line.
Claim 17
Dependent Claim
19 words
The apparatus defined in claim 12 further comprising: a plurality of said compensating networks inserted into said transmission line.
Claim 18
Dependent Claim
27 words
The apparatus defined in claim 12 wherein said transmission line comprises a plurality of small diameter conductors twisted together to form a composite conductor of desired resistance.
Claim 19
Dependent Claim
58 words
The apparatus defined in claim 11 wherein said time constant of said compensation network is determined by the equation R= √L/C when: R= the resistance of said network and of said transmission line caused by skin effect, said resistances being equal, L= the inductance of said transmission line caused by skin effect, C= the capacitance of said network.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1980-08-15 | 1981-02-14 | 1981-08-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-08-15 | 1985-02-14 | 1985-08-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-08-15 | 1989-02-14 | 1989-08-16 | $7700.00 | Window Closed / Lapsed |