US3863024A - Directional coupled data transmission system - Google Patents

Directional coupled data transmission system Download PDF

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Publication number
US3863024A
US3863024A US427768A US42776873A US3863024A US 3863024 A US3863024 A US 3863024A US 427768 A US427768 A US 427768A US 42776873 A US42776873 A US 42776873A US 3863024 A US3863024 A US 3863024A
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Prior art keywords
coupling
transmission line
coupler
directional
signal
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US427768A
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English (en)
Inventor
Edward S Caragliano
Howard H Nick
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International Business Machines Corp
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International Business Machines Corp
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Priority to US427768A priority Critical patent/US3863024A/en
Priority to DE19742451487 priority patent/DE2451487C3/de
Priority to CA213,803A priority patent/CA1019455A/en
Priority to JP49133735A priority patent/JPS5235963B2/ja
Priority to FR7441921A priority patent/FR2256608B1/fr
Priority to GB5173574A priority patent/GB1460954A/en
Priority to IT30513/74A priority patent/IT1027653B/it
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Publication of US3863024A publication Critical patent/US3863024A/en
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L25/00—Baseband systems
    • H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines
    • H04L25/03—Shaping networks in transmitter or receiver, e.g. adaptive shaping networks
    • H04L25/03006—Arrangements for removing intersymbol interference
    • H04L25/03012—Arrangements for removing intersymbol interference operating in the time domain
    • H04L25/03114—Arrangements for removing intersymbol interference operating in the time domain non-adaptive, i.e. not adjustable, manually adjustable, or adjustable only during the reception of special signals
    • H04L25/03127—Arrangements for removing intersymbol interference operating in the time domain non-adaptive, i.e. not adjustable, manually adjustable, or adjustable only during the reception of special signals using only passive components

Definitions

  • ABSTRACT A combination is provided of a directional coupler connected in a transmission line ofa data transmission system and an encoding means for generating the data bits of information which, when coupled through the directional coupling means, produces a coupled signal having a substantially fixed width regardless of the length of the transmission line traversed and a height which diminishes comparatively slowly with the transmission line length traversed.
  • the directional coupling means has a coupling coefficient of at least 0.5 and has an electrical length which is substantially equivalent to one quarter of a bit'length of the encoded information.
  • the encoding means for the data bits of information generate at least one of the encoded bits identified by a full cycle signal having an equal positive and negative excursion.
  • VCOUP1 r- VCOUPZ
  • SHEET 7 OT 8 450 A MAXIMUM EVYSE AMPL
  • WIDTH (NS- MV.) 5500 VS m w SIN+COUPLER 000 BIFREQUENCY X BLFREQUENCY ALSO 0.0+ COUPLER COMPLEMENTARY A 025 SINUSOIDAL BIFREQUENCY 2000 BIFREOUENCY X LCOUPLER wTTH COUPLER 1500 COMPLEMENTARY SINUSOIDAL+COUPLER 1000- SINUSOIDAL WITH COUPLER SINUSOIDAL CABLE LENGTH YET.)
  • An equalizer is a unit which usually has the exact opposite transfer characteristics of the transmission lineso that the signals, after passing through the transmission line, are essentially corrected by the equalizerby putting the opposite distortion, etc., into the signal to bring it back to a desired amplitude and shape.
  • These transmission systems also have special clocking requirements by means of which the data is maintained synchronized at various stations along the transmission line.
  • transmission loops have become necessary wherein a number of input/output stations are connected. These transmission lines are called loop systems since they are usually ser viced by a central host computer which transmits the data along the line where it can be picked off at each station and new information entered on the transmission line if desired.
  • the location of the input/output stations is limited to a certain length of transmission line if the desired reliability is to be maintained. It will be appreciated, that the transmission line introduces sufficient amplitude'distortion and linear phase shift to the data signals so as to limit the transmission line distance at which the receiver is capable of distinguishing the intelligence carried by the data. This distance has been improved somewhat by the use of the previously described equalizers. However, an equalizer is designed for use with a particular length of cable.
  • an equalizer designed for that length must be used.
  • an equalizer designed for use with a specific transmission line length does not work as well with a transmission line length of a different length or at least of any substantial difference in length. It is not only necessary to maintain sufficient amplitude to distinguish the signal from the noise, etc., but it is also necessary to maintain sufficient signal width and height to be able to strobe the signal to detect the information and abstract the clock information.
  • the invention consists of the combination of a directional coupler connected in a transmission line of a data transmission system and an encoding means for generating the data bits of information which, when coupled through the directional coupling means, produces a coupled signal having a substantially fixed width regardless of the length of the transmission line traversed and a height which diminishes comparatively slowly with the transmission line length traversed.
  • the directional coupling means has a coupling coefficient of at least 0.5 and has an electrical length which is substantially equivalent to one quarter of a bit length of the encoded information.
  • the encoding means for the data bits of information generate at least one of the encoded bits identified by a full cycle signal having an equal positive and negative excursion.
  • FIG. 1 is a schematic diagram showing a data transmission system with' a directional coupler located in the transmission line.
  • FIG. 2 is a schematic diagram showing the directional coupler of FIG. 1 in more detail.
  • FIG. 2A is a schematic diagram showing two directional couplers for connecting into the transmission line.
  • FIG. 3 is a schematic representation showing three waveforms for representing the information in the encoded bits.
  • FIG. 4 shows a representative input waveform and the waveforms generated in coupling the input through the coupler to get the resultant output waveform.
  • FIG. 5 is a graph showing the eye pattern obtained using bi-frequency encoding after travelling through 1,500 feet of cable.
  • FIG. 6 is a graph showing the eye pattern obtained after travelling through 3,000 feet of cable utilizing a bi-frequency encoding.
  • FIG. 7 is a graph showing the eye pattern obtained after travelling through 3,000 feet of cable using the bifrequency encoding with a coupler connected in the transmission line.
  • FIG. 8 is a graph showing the rate of change of the height to the width from the center of the eye after travelling through 2,500 feet of cable for various encoding schemes.
  • FIG. 9 is a graph of the maximum eye pattern amplitude versus the cable length for various encoding schemes.
  • FIG. is a graph showing the plot of the maximum eye width versus the cable length for various encoding schemes with and without the directional coupler.
  • FIG. 11 is a graph showing the plot of the maximum height times the maximum width versus the cable length for various encoding schemes with and without the directional coupler.
  • FIG. 12 is a graph showing the plot of eye width versus cable length for various encoding schemes with and without the directional coupler.
  • FIG. 1 there is shown a data transmission system in which the data is put on the transmission line 12 by a transmitter 10 and is utilized or received from the transmission line 12 by a receiver 14.
  • a directional coupler 15 In the transmission line 12 before the receiver 14, there is located a directional coupler 15, the use of which in connection with the encoding selected forms the invention of this application.
  • the directional coupler depicted in FIG. 2 is a strip line directional coupler wherein two parallel adjacent printed circuit strip lines are separated a short distance by a material having an appropriate dielectric constant. This arrangement is located between two ground planes which are inductively and capacitively coupled so that the edges of a first pulse, of fast rise and fall time characteristics, propagating along one line, produces a positive pulse and a negative pulse in the other line.
  • the lines are back-coupled or directional in that the thus produced pulses propagate along the second line in a direction opposite to the direction in which the first pulse propagates along the first line.
  • the energy transferred between the coupling segments of the two element directional coupler is affected by the various physical characteristics of the directional coupler such as the length, width and distance between the coupling segments.
  • the two conductive segments 16 and 18 are shown extending parallel to one another and separated by a noneonductive sheet of material 20 such as epoxy glass having an appropriate dielectric constant.
  • a nonconductive sheet of material is also located above the top conductor and below the bottom conductor. These conductors and separating sheets are located between the two ground planes 22 and 24 which usually consist of sheets of copper arranged one above the top conductor l6 and one below the bottom conductor 18 separated therefrom by the respective non-conductive sheet.
  • the first line or coupling segment 16 has an input A located at one end and a terminating resistance 26 located at the other end. As can be seen from FIG. 2, the input A receives the encoded data being transmitted on the transmission line 12, which data travels along the coupling segment 16 from left to right towards the terminating resistor 26.
  • the terminating resistor 26 matches the coupling segment to the characteristic impedance of the transmission line 12.
  • the coupling of the encoded data signal takes place along the coupling segment 16 to the coupling segment 18.
  • the signal coupled into coupling segment 18 travels in the opposite direction to the signal travelling along the coupling segment 16 as shown by arrows in both segments.
  • the coupled signal passes from the directional coupler at the output terminal B and is received by the receiver 14.
  • coupling segment 18 at the right end thereof has a terminating resistor 28 which matches the coupling segment to the characteristic impedance of the transmission line 12.
  • the coupler operation depends upon the steepness of the incident pulse rise and fall.
  • the width or duration of the pulse produced by the coupling is determined by the length L of the two segments 16 and 18 in parallel.
  • the performance of the coupler is related to the impedances offered to signals on the transmission lines and the coupling ratio, which are determined mainly by the distance between the coupling segments in the coupled region and the dielectric constant of the material separating the two. It has been determined that coupling segments of electrical length 1- will produce a pulse having a time duration equal to 2 1-. For example. a l-volt amplitude input signal applied to the input terminal A of coupling segment 16 when the coupler has a coupling coefficient K of 0.5 and an electrical length r of 2 nsec, will produce an output pulse having a time duration of 4 nsec and a pulse amplitude of one-half a volt.
  • the directional coupler described above is found to produce the desired enhancement of the data transmitted along the transmission line where the coupler has an electrical length 1' equal to one-fourth of the bit time and when the data is encoded such that the information is represented by-bits at least one of which has a positive and negative swing over a full cycle.
  • the coupler has an electrical length 1' equal to one-fourth of the bit time and when the data is encoded such that the information is represented by-bits at least one of which has a positive and negative swing over a full cycle.
  • FIG. 3 three known encoding schemes are shown for the information bits 1 and 0, all of which exhibit the desired waveform enhancing when used with the particular directional coupler.
  • the bifrequency encoding shows the 1 bit as a positive voltage for a half cycle followed by a negative voltage for the rest of the cycle and the zero bit as just the opposite, that is, a negative signal for a half cycle followed by a positive signal over the rest of the cycle.
  • the bifrequency encoding scheme is a nonreturn-to-zero type of encoding.
  • the sinusoidal encoding shows a sinusoidal signal starting at zero and going full cycle to 360 for representing the one bit and shows no signal representing the zero bit.
  • the complementary sinusoidal encoding is shown as a full sine wave representing the one bit and the opposite thereof representing the zero bit.
  • These encoding schemes are used in data transmission systems because they introduce bits from which the information can be extracted. It should be appreciated that these encoding schemes produce pulses whose characteristics are dependent on which information bit, a zero or one, precedes and follows it. Thus, we have an information bit which can be zero or one and which can be preceded and followed by a bit which can be zero or one. Thus, we have 2 or eight possibilities. The eight combinations are as follows: 111, 110, I01, 100, 011, O01, 010, and 000.
  • FIG. 4 there is shown a sinusoidal voltage input signal which is preceded by a zero and followed by a zero. As previously mentioned, the zero is represented in sinusoidal encoding by no signal.
  • This sinusoidal encoded signal is sent into the coupler of the present invention which is tuned to have an electrical length 7 equal to one-fourth of a bit time.
  • the directional coupler transformation characteristic may be expressed in the time domain by the following Laplace Transform:
  • Vcoupled equals the voltage of the coupled pulse
  • Vin equals the voltage of the input pulse
  • k equals the coupling coefficient of the coupler
  • r equals the electrical length of the coupling region. Since the coupling coefficient k is a constant less than unity and r is a fixed constant, the coupling output is expressable as the sum of the delayed, attenuated and phase shifted reproductions of the input. As previously mentioned, k is equal to 0.5 and 'r is equal to one-fourth of a bit time in this invention.
  • the various pulses proucked in the second coupling-segment as the result of Vin, shown in FIG. 3, are shown as Vcoupled l, Vcoupled 2 and Vcoupled 3.
  • Vcoupled is approximately equal to Vcoupled l Vcoupled 2 Vcoupled 3.
  • the first swing of the output waveform of Vcoupled is half the amplitude of the positive swing of Vin. This is in accordance with the coupling ratio of 0.5.
  • the negative swing is 0.875 in amplitude.
  • strobing In data transmission systems, in order to extract the information, it is necessary to strobe the data pulses. This so-called strobing requires that the pulse carrying the information is of sufficient width and amplitude to be easily detected. The actual strobing is done on the second half cycle of the data waveform. Referring to FIG. 4, it can be seen that the use of the directional coupler enhances the second half of the cycle as shown in the Vcoupled waveform.
  • a convenient way of analyzing the encoded data pulses on a transmission line is to superimpose the eight combinations of the waveform at a particular point in the transmission line. These superimposed waveforms are called eye patterns. A typical eye pattern is shown in FIG.
  • first eye 30 and second eye 32 each extend I00 millivolts above and below the 0 millivolt line. Each eye extends in width approximately 7% nanoseconds.
  • This particular eye was developed using a bifrequency type of encoding and a 2 volt peak-to-peak input signal reproduced after travelling through 1,500 feet of cable.
  • 8 waveforms are shown, all at the same point, representing all eight combinations of three pulses having two possibilities each (2
  • Each of the eight possibilities 000 through I 1 l are clearly identified in FIG. 5.
  • the second half of the eye as well as the first half has a clearly defined height and width for extracting the information as to whether the waveform repre- $I I 9H Q P- Referring to FIG.
  • FIG. 7 there is shown the eye pattern obtained after travelling through 3,000 feet of cable using the same bifrequency encoding as was used in FIG. 6.
  • the eye 34 is quite clearly defined in both height and width.
  • the first eye in the pattern has been for all practical purposes destroyed.
  • FIG. 4 it should be recalled that there is an energy transformation which takes place from the first eye to the second eye in a data waveform when a directional coupler is introduced.
  • FIG. 7 a coupler is introduced into the transmission line at the end of the 3,000 feet of cable.
  • the contrast between the eye pattern of FIG. 6 and FIG. 7 is quite clear. It should be remembered, that the second half of the eye is used for the strobing to obtain the information from the waveform.
  • FIG. 6 and FIG. 7 were developed using the same bifrequency encoded data travelling in equal lengths of cable, the only difference being the introduction of the directional coupler in the case of FIG. 7.
  • the enhancement of the signal produced by the introduction of the directional coupler with this type of data encoding is clearly represented. It has also been found that longer lengths of cable can be used which results in a diminishing of the height of the second eye of the pattern but not the width. Thus, the width of the second eye is not affected by the length of the cable traversed.
  • FIG. 8 shows the differential signal in millivolts which can be obtained from the second half of the eye pattern after travelling through 2,500 feet of cable using the previously described encoding schemes with and without a directional coupler. More specifically, the rate of change of the height with distance measured along the width from the center of the eye is shown.
  • FIG. 9 shows the plot of maximum eye amplitude versus cable length for each of the six previously mentioned cases. For example, given a 50 m.v. maximum eye amplitude requirement, the following maximum lengths are achievable with each of the given schemes:
  • FIG. 10 shows the maximum eye width versus the cable length for each of the previously mentioned six cases. For example, given a 6 nanosecond minimum width requirement the following maximum lengths are achievable with each of the schemes:
  • the bifrequency encoding scheme produces a 280 percent cable length increase without causing the eye to go below a minimum width requirement when a directional coupler is used.
  • FIG. 11 shows a plot of the product of the maximum width and maximum height versus cable length for each of the six cases mentioned. This plot provides a measure of the eyes area for the various cases previously mentioned as a function of length of cable. Looking at the plot of the bifrequency data encoding it can be seen that after 3,000 feet of cable there is no appreciably eye measurement obtainable. However, in the case of the bifrequency plot with the coupler there is an appre-. ciable area indicated for 3,500 feet of cable.
  • FIG. 12 is a plot of the eye width versus cable length for an aribtrarily chosen minimum eye amplitude of m.v.
  • the same six cases are plotted consisting of the three encoding schemes with and without directional coupler.
  • the complementary sinusoidal plot without the coupler is not shown since it is approximated by the bifrequency without the coupler plot. If a minimum eye width of 6 us is required, the maximum achievable distance for the six cases is as follows:
  • FIG. 2A there is shown the schematic diagram of a second embodiment of the directional coupler which can be connected into the transmission line 12 of FIG. I.
  • This further embodiment consists of a second directional coupler 40 connected to the first directional coupler 44. As can be seen, the connections are made such that the input 36 to the first coupling segment 38 of the second coupler 40 is connected to the output 42 of the first coupling segment 46.
  • the other end of the first coupling segment 38 of the second coupler 40 is connected to ground through a terminating resistor 48 introducing an impedance which is the equivalent of the characteristic impedance of the transmission line to which the coupler is connected.
  • the output 49 of the second coupling segment 50 of the first coupler 44 is connected to the input 52 of the second coupling segment 54 of the second coupler 40 as shown in FIG. 2A.
  • the other end of the second coupling segment 54 of the second coupler 40 is connected to ground through a terminating resistance 56 which is equivalent to the characteristic impedance of the transmission line.
  • the output of the directional coupler means is taken from output B at the left end of second coupling segment 54. This output is connected to point B in the transmission line 12 of FIG. 1.
  • the input signal to the first coupling segment 46 of the first coupler 44 is coupled to the second coupling segment travelling in the opposite direction as shown by the arrows.
  • This coupled pulse is applied to the second coupling segment 54 of the second coupler 40 at the input end 52 thereof and travels toward the terminated end and the output as shown by the arrow.
  • the input signal travels to the right in the first coupling segment 38 of the second coupler 40 as shown by the arrow.
  • This causes coupling of a signal to the second coupling segment 54 travelling in the left hand direction which enhances the signal already travelling therein as a result of the connection to the output 49 of the second segment 50 of the first coupler 44. It has been found that a pair of directional couplers 44, 40 connected as shown in FIG.
  • directional couplers can be added to the pair of couplers mentioned above with connections similar to those used for connecting directional coupler 40 to 44. These additional couplers will, if properly connected, further enhance the input signal to give increased amplitude to the second eye of the eye pattern.
  • the use of directional coupler means in the data transmission line of a data transmission system conveying encoded information bits of data provides a means of enhancing the encoded data signals. Accordingly, the prior limitations as to cable length are relaxed. Also, the signal to noise ratio is improved and the sensitivity of the receiver-amplifier can also be relaxed. Be-
  • directional coupling means located in said transmission line and an encoding means for generating the data bits of information which when coupled through said directional coupling means produces a coupled signal having a substantially fixed width regardless of the length of transmission line traversed and a height which diminishes comparatively slowly with transmission line length traversed;
  • said directional coupling means having a coupling coefficient of at least 0.5 and having an electrical length which is substantially equivalent to one quarter of a bit length;
  • said encoding means for the data bits of information generating at least one of the encoded bits identified by a full cycle signal having an equal positive 7 and negative excursion.
  • said directional coupler means connected in said transmission line comprises:
  • a first coupling segment connected at one end thereof to a first length of said transmission line and terminated at the other end. thereof in a resistance equal to the characteristic impedance of transmission line;
  • said first and second coupling segments being coextensive with said terminated ends adjacent one another and located between ground planes and at a distance from one another to give the desired coupling from the first coupling segment to the second coupling segment in a backward direction.
  • said encoding means is represented by two bits of information, each extending for a full cycle having an equal positive and negative excursion in a nonreturn to zero form, one bit consisting of a positive signal for a half cycle followed by a negative signal for a half cycle, the other bit consisting of a negative signal for a half cycle followed by a positive signal for a half cycle.
  • said encoding means is represented by two bits of information, each extending for a full cycle in a return to zero form; one bit consisting of a sinusoidal waveform starting with a positive half cycle followed by a negative half cycle, the other bit consisting of the absence of a signal for a full cycle.
  • said encoding means is represented by two bits of information, each extending for a full cycle in a return to zero form, one bit consisting of a sinusoidal waveform starting with a positive half cycle followed by a negative half cycle, the other bit consisting of a sinusoidal waveform starting with a negative half cycle followed by a positive half cycle.
  • said directional coupling means is a strip line directional coupler consisting of printed circuit first and second coupling segments separated by a material having a high dielectric constant.
  • first coupling segment and said second coupling segment are of the same length, width, and thickness and are located equally distant from one another along the width dimension.
  • strip line directional coupler is located between and separated from thin copper sheets forming ground planes therewith by high dielectric constant material.
  • said directional coupler means comprises a first and second directional coupler, each having a first and second coupling segment,
  • the input end of said first coupling segment of said first directional coupler is connected to the transmission line connected to the transmitter so as to receive said encoded data bits of information, the other end of said first coupling segment of said first coupler is connected to the input end of the first coupling segment of said second coupler, the output end of said first coupling segment of said second coupler having a resistor connected thereto to ground providing an impedance equal to the characteristic impedance of the transmission line;
  • the second coupling segment of said first coupler has the output end connected to the input end of the second coupling segment of said second coupler
  • rectional couplers are connected in series but each having the input and output thereof reversed with respect to said first coupling segments so that the signal coupled from said first coupling segments travels in the opposite direction in said second coupling segments;
  • the output from the last second coupling segment of said plurality of directional couplers is connected to the transmission line connected to the receiver.
  • the coupled signal being enhanced in amplitude by each of said plurality of couplers.

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Dc Digital Transmission (AREA)
  • Cable Transmission Systems, Equalization Of Radio And Reduction Of Echo (AREA)
  • Waveguide Connection Structure (AREA)
  • Bidirectional Digital Transmission (AREA)
US427768A 1973-12-26 1973-12-26 Directional coupled data transmission system Expired - Lifetime US3863024A (en)

Priority Applications (7)

Application Number Priority Date Filing Date Title
US427768A US3863024A (en) 1973-12-26 1973-12-26 Directional coupled data transmission system
DE19742451487 DE2451487C3 (de) 1973-12-26 1974-10-30 Datenübertragungsanordnung mit Richtungskopplern
CA213,803A CA1019455A (en) 1973-12-26 1974-11-15 Directional coupled data transmission system
JP49133735A JPS5235963B2 (it) 1973-12-26 1974-11-22
FR7441921A FR2256608B1 (it) 1973-12-26 1974-11-28
GB5173574A GB1460954A (en) 1973-12-26 1974-11-29 Distortion reduction in data transmission systems
IT30513/74A IT1027653B (it) 1973-12-26 1974-12-13 Sistema di trasmissione di dati mediante accopriatore direzionale

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US427768A US3863024A (en) 1973-12-26 1973-12-26 Directional coupled data transmission system

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US3863024A true US3863024A (en) 1975-01-28

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JP (1) JPS5235963B2 (it)
CA (1) CA1019455A (it)
FR (1) FR2256608B1 (it)
GB (1) GB1460954A (it)
IT (1) IT1027653B (it)

Cited By (9)

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Publication number Priority date Publication date Assignee Title
US3970927A (en) * 1973-11-30 1976-07-20 Plessey Handel Und Investments A.G. Method and apparatus including a sensing head with a pair of strip transmission lines for detecting metallic objects
US3979699A (en) * 1974-12-23 1976-09-07 International Business Machines Corporation Directional coupler cascading for signal enhancement
FR2544937A1 (fr) * 1983-04-21 1984-10-26 Telefunken Fernseh & Rundfunk Circuit demodulateur de signal biphase
US5365205A (en) * 1993-05-20 1994-11-15 Northern Telecom Limited Backplane databus utilizing directional couplers
US6091739A (en) * 1997-10-31 2000-07-18 Nortel Networks Corporation High speed databus utilizing point to multi-point interconnect non-contact coupler technology achieving a multi-point to multi-point interconnect
US20110156843A1 (en) * 2009-12-24 2011-06-30 Samsung Electro-Mechanics Co., Ltd. Printed circuit board and transmitting/receiving module including the same
US20130334890A1 (en) * 2012-06-13 2013-12-19 Advanced Micro Devices, Inc. Contactless Interconnect
US9647314B1 (en) * 2014-05-07 2017-05-09 Marvell International Ltd. Structure of dual directional couplers for multiple-band power amplifiers
US10027292B1 (en) * 2016-05-13 2018-07-17 Macom Technology Solutions Holdings, Inc. Compact dual diode RF power detector for integrated power amplifiers

Families Citing this family (2)

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Publication number Priority date Publication date Assignee Title
JPS5226140A (en) * 1975-08-22 1977-02-26 Nippon Telegr & Teleph Corp <Ntt> Partial response equalizer
JPH01300719A (ja) * 1988-05-30 1989-12-05 Sony Corp 乗物内の情報伝送装置

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US3438029A (en) * 1967-06-30 1969-04-08 Texas Instruments Inc Distributive manifold
US3516065A (en) * 1967-01-13 1970-06-02 Ibm Digital transmission system
US3657701A (en) * 1970-11-02 1972-04-18 Texas Instruments Inc Digital data processing system having a signal distribution system
US3794759A (en) * 1972-12-26 1974-02-26 Ibm Multi-terminal communication apparatus controller

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US3516065A (en) * 1967-01-13 1970-06-02 Ibm Digital transmission system
US3438029A (en) * 1967-06-30 1969-04-08 Texas Instruments Inc Distributive manifold
US3657701A (en) * 1970-11-02 1972-04-18 Texas Instruments Inc Digital data processing system having a signal distribution system
US3794759A (en) * 1972-12-26 1974-02-26 Ibm Multi-terminal communication apparatus controller

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3970927A (en) * 1973-11-30 1976-07-20 Plessey Handel Und Investments A.G. Method and apparatus including a sensing head with a pair of strip transmission lines for detecting metallic objects
US3979699A (en) * 1974-12-23 1976-09-07 International Business Machines Corporation Directional coupler cascading for signal enhancement
FR2544937A1 (fr) * 1983-04-21 1984-10-26 Telefunken Fernseh & Rundfunk Circuit demodulateur de signal biphase
US5365205A (en) * 1993-05-20 1994-11-15 Northern Telecom Limited Backplane databus utilizing directional couplers
US6091739A (en) * 1997-10-31 2000-07-18 Nortel Networks Corporation High speed databus utilizing point to multi-point interconnect non-contact coupler technology achieving a multi-point to multi-point interconnect
US20110156843A1 (en) * 2009-12-24 2011-06-30 Samsung Electro-Mechanics Co., Ltd. Printed circuit board and transmitting/receiving module including the same
US8319574B2 (en) * 2009-12-24 2012-11-27 Samsung Electro-Mechanics Co., Ltd. Printed circuit board and transmitting/receiving module including the same
US20130334890A1 (en) * 2012-06-13 2013-12-19 Advanced Micro Devices, Inc. Contactless Interconnect
US9431168B2 (en) * 2012-06-13 2016-08-30 Advanced Micro Devices, Inc. Contactless interconnect
US9647314B1 (en) * 2014-05-07 2017-05-09 Marvell International Ltd. Structure of dual directional couplers for multiple-band power amplifiers
US10027292B1 (en) * 2016-05-13 2018-07-17 Macom Technology Solutions Holdings, Inc. Compact dual diode RF power detector for integrated power amplifiers
US10651805B2 (en) 2016-05-13 2020-05-12 Macom Technology Solutions Holdings, Inc. Compact dual diode RF power detector for integrated power amplifiers

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DE2451487B2 (de) 1976-05-26
JPS5235963B2 (it) 1977-09-12
JPS5098215A (it) 1975-08-05
GB1460954A (en) 1977-01-06
IT1027653B (it) 1978-12-20
FR2256608A1 (it) 1975-07-25
FR2256608B1 (it) 1976-10-22
CA1019455A (en) 1977-10-18
DE2451487A1 (de) 1975-08-28

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