US2457212A - Time-delay network - Google Patents

Description

Search Emma 7 Dec. 28, 1948. M. J. DI TORO 2,457,212

TIME-DELAY NETWORK Filed June 18, 1945 2 Sheets-Sheet 2 Volts Volts FIG.9

Volts Volts INVENTOR. MICHAEL J. Di TORO ATTOR Patented Dec. 28, 1948 TIME-DELAY NETWORK Michael J. Di Toro, Brooklyn, N. Y., assignor, by mesne assignments to Hazeltine Research, Inc., Chicago, 111., a. corporation of Illinois Application June 18, 1945, Serial No. 599,985

13 Claims. 1

This invention relates, in general, to time-delay networks for translating signal pulses. While being subject to a variety of applications, the invention has particular utility in a time-delay network adapted to translate signal pulses having a duration which may be less than the delay of the network and will be described in detail in that connection.

Time-delay networks, as such, have long been known in the art and are of the balanced or unbalanced type. In the former, a pair of distributed or elongated windings are concentrically arranged and insulated from but electrically coupled to one another along their lengths to provide distributed inductance and distributed capacitance in the network. The unbalanced network, on the other hand, includes a single distributed winding concentrically arranged about and insulated from but electrically coupled along its length to a conductive member, such as a conductive core structure, to provide distributed inductance and capacitance in the network. In each instance, the network simulates a transmission line and has a time delay proportional to the geometric means of its total eifective series inductance and total eilective shunt capacitance. Where long time delays are to be realized with networks of practical and useful physical dimensions, the distributed windings have a large number of turns per unit length and are frequently wound over core structures of high permeability to increase the series inductance of the network.

Arrangements of the type described are satisfactory for many installations but are subject to a particular type of phase distortion which may be undesirable in other installations. This distortion is attributable to the substantial inductive coupling which exists between winding turns and which, as will be made clear hereinafter, tends to produce asymmetrical distortion of an applied symmetrical pulse. This effect is especially pronounced where the network includes a highpermeability core structure and when translating pulses having a duration that is short with reference to the network delay.

Prior art arrangements have been proposed in which the winding turns have such a large spacing that the interturn inductive coupling is minimized to avoid, at least in part, the distortion mentioned. Such structures are undesirable in that they become of unwieldy physical sizes when used to obtain long time delays. It has also been proposed that a complex core structure be used with the winding having a large spacing between turns. The core structure is anisotropic, having a low permeability in an axial direction and a high permeability in a radial direction further to reduce the coupling between turns. This construction is undesirable in view of the difliculty in fabricating the core and because of the large physical dimensions of the network necessary to obtain long time delays.

It is an object of the present invention, therefore, to provide an improved time-delay network for translating signal pulses and which avoids one or more of the above-mentioned limitations of prior art arrangements.

It is another object of the invention to provide a time-delay network for translating signal pulses and including an improved and simplified arrangement for controlling the operating characteristics of the network.

It is a specific object of the invention to provide an improved time-delay network for translating signal pulses with a minimum phase distortion even though the translated pulse may have a duration less than the delay of the network.

In accordance with the invention, a time-delay network for translating a signal pulse comprises an elongated conductive member and an elongated winding. The winding is insulated from but electrically coupled along a major portion of its length to the conductive member for providing a distributed capacitance in the network and has a substantial inductive coupling between turns tending to produce a transient distortion pulse in response to an applied signal pulse. A condenser is bridged across a preselected number of turns of the winding. The value of the condenser and the number of preselected turns bridged thereby are so chosen as to produce, in response to the applied signal pulse and superimposed on the delayed pulse output, a short pulse comparable in amplitude but opposite in polarity to the distortion pulse and occurring ahead of the leading edge of the delayed pulse output in substantial coincidence with the distortion pulse.

For a better understanding of the present invention, together with other and further objects thereof, reference is had to the following description taken in connection with the accompanying drawings, and its scope will be pointed out in the appended claims.

In the drawings, Fig. l is a schematic representation of a three-terminal time-delay network in accordance with the invention; Fig. 2 is an end view of the network represented by Fig. 1; Fig. 3 is a schematic circuit diagram of the arrangement of Fig. 1; Fig. 4 comprises a series of curves utilized in explaining the operation of the Fig. 1 network; Figs. 5 and 6 individually represent different modifications of the three-terminal network of Fig. 1: Fig. 7 is a schematic representation of a four-terminal time-delay network in accordance with the invention; Fig. 8 represents a modification of the network of Fig. 7; while Fig. 9 comprises a series of curves utilized in explaining the operation of the network of Fig. 8.

Referring now more particularly to Fig. 1, the time-delay network there represented is of the unbalanced or three-terminal type and is adapted to translate signal pulses having a duration which may be less than the delay of the network. The network is in the form of a simulated transmission line and comprises an elongated conductive member, especially, a supporting conductive core I0. Preferably, the material of core structure I0 is such as to provide a high permeability for a purpose to be made clear hereinafter. This core may include comminuted graphite and iron particles molded into a conductive rod of any desired cross section and longitudinal length. In order that signals translated through the network may undergo a minimum attenuation, it is desirable that core member I0 have a construction as particularly disclosed in copending application Ser. No. 582,283, filed March 12, 1945, in the name of Michael J. Di Toro and assigned to the same assignee as the present invention. This application has issued as Patent No. 2,413,607, December 31, 1946.

The network also includes a uniformly distributed or elongated winding I I mounted in concentric rclationship with respect to the conductive core Ill. The turns of winding II are closely spaced and have a substantial inductive coupling therebetween which tends to cause asymmetrical distortion in one sense of an applied symmetrical pulse, as will be made clear hereinafter. A sleeve I2 of dielectric material, interposed between core structure l0 and winding II, causes the winding to be insulated from but electrically coupled along a major portion of its length to the core structure for providing a distributed capacitance in the network. Sleeve I2 may be formed by wrapping a dielectric paper around core structure I0. Preferably, the dielectric paper is to be shaped as disclosed in copending application Ser. No. 599,987, filed June 18, 1945, in the name of Michael J. Di Toro and assigned to the same assignee as the present invention. This application has issued as Patent No. 2,454,865, November 30, 1948. Briefly, the shaping of the dielectric paper is to be such that the sleeve I2 has in creased thickness in the vicinity of the end portions of winding II to compensate for end effects of the coil as described in the last-mentioned copending application.

The distributed capacitance between winding II and core structure II], in conjunction with the inductance of winding Ii, determines the time delay of the network. It is well understood that the time delay of any such network is proportional to the geometric mean of its total effective series inductance and total effective shunt capacitance. The diameter, length and permeability of core structure I0, the size and type conductor utilized in fabricating winding II, as well as the number and pitch of winding convolutions are selected to afford such values of total series inductance and total shunt capacitance that the network produces a desired time delay. In this connection, it will be appreciated that an increase in the diameter or length of the core structure and winding results in higher values of inductance and capacitance, while increasing the number of turns per unit length of the winding effects primarily only the value of inductance. Likewise, the inductance alone may be increased to a desired value by proportioning the constituent elements of core structure I0 for higher permeability.

Winding I I is provided with an input terminal I3 for applying signal pulses to the network and an output terminal I4 for deriving delayed signal outputs therefrom. The conductive core structure I0 is coupled to a common terminal I5 of the network which is usually a ground connection.

A condenser is bridged across a preselected number of turns of winding II for providing a bridging capacitance in the network. This condenser comprises a longitudinally-slotted conductive member or ring 20 supported in substantially coaxial relation with reference to winding II and spaced in a preselected manner intermediate its input and output terminals I3 and I4, respectively. A sleeve 2I of dielectric material having the same axial length as conductive ring 20 is interposed between the ring and the Winding and insulates, but electrically couples the ring along its length to, the winding to form a bridging condenser. In other words, one electrode of the condenser comprises the ring 20 while the opposite electrode thereof is provided by the winding turns enclosed by the ring.

The bridging condenser may be conveniently constructed by utilizing for elements 20 and 2I a ring of polystyrene having an external and longitudinally-slotted thin metallic coating. Copper or silver may be utilized in coating the ring of polystyrene. A conductor 22 is connected between conductive ring 20 and a preselected point on winding II so that the bridging condenser bridges a preselected number of winding turns. For the illustrated embodiment where conductor 22 connects with input terminal I3, the position of ring 20 intermediate the end portions of the winding is adjusted so that the condenser bridges the desired number of turns.

The value of the bridging condenser and the number of preselected winding turns bridged thereby are so chosen that this condenser produces in response to an applied signal pulse and superimposed on the delayed pulse output a short pulse occurring ahead of the leading edge of the delayed pulse by a predetermined time interval, as will be made clear presently. The value of the condenser is determined by the longitudinal length of conductive ring 20 and its coupling with winding I I. The number of turns bridged thereby is determined by the position of ring 20 and the connection to the winding of conductor 22.

The network of Fig. l is represented by the schematic circuit diagram of Fig. 3 in which corresponding components are identified by the same reference numerals. The bridging condenser, however, is conveniently designated Cb. The network will be seen to constitute an unbalanced or three-terminal network as it includes input terminal I3, output terminal I4, and a ground terminal I5. It has distributed inductance provided by the uniformly distributed winding I I and distributed capacitance comprising the capacitance between winding II and core structure III. The bridging condenser Cb, in the instant embodiment of the invention, is connected with winding II as indicated atA and forms, with the impedance looking into the network at this junction point A, a differentiating circuit to provide phase correction in the network.

In considering the phase-correction phenomena, reference is made to the curves of Fig. 4 in which curve B represents a stepped pulse or signal applied to input terminal l3 at the time 151. If the effect of bridging condenser Cb is momentarily neglected, the delayed output pulse obtained from the network may be as indicated by curve C. The delayed pulse output occurs at the time ts, where t1ta indicates the time delay of the network. The delayed pulse output is preceded by unwanted transient distortion pulses or echoes including a negative leading echo P1 of substantial intensity. The echo is said to be negative because it has a polarity opposite to that of the applied pulse. It represents an asymmetrical phase distortion which results from the substantial inductive coupling between turns 01 the distributed winding II. This echo leads the delayed output pulse by the time interval tz-tz.

Considering now the effect of bridging condenser Cb, it will be apparent that the applied signal pulse of curve B is differentiated by the differentiating circuit, described above, including the bridging condenser. The differentiation produces the short pulse of curve D. Since the bridging condenser bridges a part of winding H, the pulse of curve D is etIectively applied to the network ahead of the pulse of curve B and consequently arrives at the output terminal I4 ahead of the delayed pulse output. It has been pointed out above that an undesired leading echo P1, representing asymmetrical distortion in the network, also appears ahead of the leading edge of the delayed pulse output. In order to eiIect a desired phase correction, the delayed output of the short pulse of curve D is superimposed upon the delayed output of the pulse of curve B but properly timed to be in phase opposition with the negative leading echo P1. To this end, the section of winding l I bridged by condenser Cb is selected to have a time delay corresponding to the interval tzt3. Therefore, the delayed output of the short pulse of curve D occurs at the output terminal [4 in time phase with the negative leading echo P1, as shown in curve E. Additionally, the value of the bridging condenser is selected so that the amplitude of the delayed short pulse of curve E is approximately equal to that of the negative leading echo P1 to produce a maximum correcting effect. This correction causes the resulting delayed pulse output of the network to appear as represented in curve F. From this curve it will be seen that a substantial phase correction is effected.

The phase-correction phenomena may be viewed somewhat differently as follows. The inductive coupling of the winding turns produces asymmetrical distortion in one sense of an applied signal, this distortion being represented in part by the negative leading echo P1 of curve C. The bridging condenser produces the delayed short pulse of curve E superimposed on the delayed signal output of curve C but occurring ahead of the leading edge of the delayed output of the applied pulse of curve B. The pulse of curve E has the same polarity as the delayed pulse output of the signal of curve B and may be considered to be a positive and compensating leading echo. Alternatively, it may be said to represent an asymmetrical distortion of the applied pulse which is in a complementary sense to that resulting from the inter-tum inductive coupling. The end result 6 is that the compensation afforded by the bridging condenser substantially reduces the phase distortion of the network.

In certain applications it may be desirable to utilize a plurality of bridging condensers of the type represented in Fig. 1 to derive a plurality of short pulses occurring ahead of the leading edge of the delayed pulse output in a time sequence selected to cancel out a plurality of echoes arising in the translation of a signal pulse through the network. This may be accomplished with the modified arrangement of Fig. 5 which is generally similar to that of Fig. 1, corresponding components thereof being identified by the same reference numerals. However. in Fig. 5 a second bridging condenser is provided. This second condenser has a construction similar to that of the first and comprises a longitudinally-slotted conductive ring 24 insulated from but electrically coupled to winding I l by way of a dielectric ring 25. An additional conductor 23 connects the second bridging condenser with input terminal 13.

The modified time-delay network translates applied signal pulses in substantially the same manner as described in connection with the network of Fig. 1. In view of the pair of bridging condensers, a pair of short pulses are superimposed upon the delayed pulse output of the network. This pair of pulses occurs in a time sequence determined by the number of turns bridged by each of the bridging condensers. For the illustrated embodiment, the pulse produced by the condenser including conductive ring 24 leads the pulse produced by the condenser including conductive ring 20. These pulses have the same polarity and may be used to advantage when the delayed output of an applied signal pulse includes a pair of spaced negative leading echoes instead of the single negative echo P1 shown in Fig. 4.

In Fig. 6 there is represented a further modification of the three-terminal network of Fig. 1 having a multiplicity of bridging condensers. The components of Fig. 6 which correspond to those of Fig. 1 are designated by the same reference numerals. Longitudinally-slotted conductive rings 25 and 21, insulated from but electrically coupled to winding II by way of dielectric rings 28 and 29, provide additional condensers in the network. These condensers are connected by way of a conductor 30. In operation, the bridging condenser comprising conductive ring 20 supplies a first short pulse in a manner described hereinbefore. The condenser comprising conductive ring 26 functions as a pick-up device for deriving a signal from an intermediate point of the network. This signal is applied over conductor 30 to the second bridging condenser 21 and appears as an additional short pulse superimposed upon the delayed pulse output of the network anad occurring in a desired time relationship with reference to that produced by the first bridging condenser comprising conductive ring 20. The time sequence and amplitudes of the pulses produced by the bridging condensers may be determined by appropriately positioning the conductive rings along the windings and by suitably selecting the longitudinal length of each.

A four-terminal and balanced time-delay network embodying the invention is represented in Fig. 7. This network comprises a pair of e1ongated and distributed windings 40 and II, the turns of each of which are so closely spaced as to have a. substantial inductive coupling. Windings 40 and 4| are arranged in concentric relationship, being insulated from but electrically coupled to one another along their lengths through a dielectric sleeve 42. This sleeve may be constructed in the manner described in connection with sleeve l2 of the Fig. l arrangement to compensate for end effects of the distributed windings. A hollow core structure 43 of insulating material supports the winding arrangement and may, if desired, include magnetic material to have a high permeability characteristic. Input terminals 44 and 44 are connected with the adjacent ends of the windings and output terminals 45 and 45' are connected with the opposite ends of the windings. A first bridging condenser is associated with the outer winding 4 I, being constructed of a longitudinally-slotted conductive ring 45 and an insulating sleeve 41 in the manner already described. This condenser is connected with input terminal 44 by means of a conductor 48. In order to maintain the balanced relationship of the winding arrangement, a second bridging condenser having the same value as the first condenser is associated in like manner with the corresponding turns of inner winding 40. The second condenser includes a longitudinally-slotted conductive ring 5!! which may comprise a metallic coating on a portion of the internal periphery of the core 43. A conductor 5l' connects the second bridging condenser with input terminal 44'. The phase correction obtained with the bridging condensers in this fourterminal network will be apparent from the description of the Fig. 1 arrangement.

In Fig. 8 there is represented a modified fourterminal network which is generally similar to that of Fig. '7, like components thereof being identified by the same reference characters. In this embodiment of the invention, however, an additional bridging condenser is associated with the outer winding 4!. It comprises a slotted conductive ring 52, an insulating sleeve 53, and a conductor 54 connecting the conductive ring to input terminal 44. -Furthermore, the bridging condenser associated with inner winding 40 is positioned intermediate the condensers coupled to outer winding 4! and the conductor 5| connects conductive ring 58 with input terminal 44.

The operation of the multiplicity of bridging condensers included in the Fig. 8 network is represented by the series of curves of Fig. 9 wherein curve B represents a stepped pulse applied at the time ii. Let it be assumed that the con struction is such as to produce an exaggerated asymmetrical distortion resulting from inter-turn inductive coupling. Where exaggerated distortion is encountered, the delayed pulse output of the applied pulse of curve B may have the Wave form of curve C. It is delayed by the interval tit'5 which is the time delay of the network. It is preceded by a series of leading echoes including the negative one Pl identified above, a positive echo P2 and an additional negative echo P3. These occur at the times t4, t3, and is, respectively. The bridging condenser comprising conductive ring 46 produces a first short pulse indicated P1 in curve E. The value of this condenser and the number of the winding turns which it bridges are selected so that the first short pulse Pi may be considered as a leading positive echo occurring in time phase with the first leading negative echo P1 and having substantially the same intensity. In similar manner, bridging condenser 50 which is excited from input terminal 44 of the outer winding 4| produces a secfrom the first short pulse P1. The value of condenser 50 and its position along winding 40 are such that the second short pulse P2 represents a negative leading echo having substantially the same magnitude and occurring in time coincidence with the positive echo P2 of curve C. The third pulse P3 of curve E is produced by the condenser including conductive ring 52. It has such magnitude, polarity, and time occurrence as to compensate the negative leading pulse P3 of curve C. Since the series of pulses represented in curve E are superimposed on the delayed signal output of the network, they compensate or annul the corresponding undesired leading echoes of curve C. Consequently, the applied signal of curve B, as obtained from output terminals 45, 45', has the wave form of curve F. In other words, the multiple bridging condensers of Fig. 8 produce such correcting effects that the delayed output of the applied pulse is obtained with substantially reduced phase distortion.

The input and output terminals permit each network arrangement to be coupled, as desired. in a signal-translating system. The network is subject to a variety of applications and may be utilized, for example, to obtain a desired time delay of applied transient signals of various durations. Through appropriate terminations of the output terminals, reflections of an applied signal may be obtained as with well known reflecting transmission-line arrangements.

One embodiment of the Fig. 1 arrangement found to have practical utility included:

Core [0:

Diameter 3 inch.

Length 5 inches.

Composition Slotted silver plated glass tube Winding l L... No. 40 Enamel wire, 250 turns per inch Sleeve l2 Polystyrene, thickness of 3 mils Ring 2| Polystyrene, thickness of 1 mil Slotted ring 20 Copper, thickness of .05 mil, .25 inch wide, spaced .38 inch from the end of winding ll While there have been described What are at present considered to be the preferred embodiments of this invention, it will be obvious to those skilled in the art that various changes and modifications may be made therein without departing from the invention. and it is, therefore, aimed in the appended claims to cover all such changes and modifications as fall within the true spirit and scope of the invention.

What is claimed is:

1. A time-delay network for translating a signal pulse comprising, an elongated conductive member, an elongated winding insulated from but electrically coupled along a major portion of its length to said conductive member for providing a distributed capacitance in said network and having a substantial inductive coupling between turns tenuing to produce a transient distortion pulse in response to an applied signal pulse, and a condenser bridged across a preselected number of turns of said winding, the value of said condenser and the number of said preselected turns being so chosen as to produce in response to said applied signal pulse and superimposed on the delayed pulse output a short pulse comparable in amplitude but opposite in polarity to said distortion pulse and occurring ahead of the leading edge of said delayed pulse in substantial coincidence with said distortion pulse.

2. A time-delay network for translating a signal pulse comprising, an elongated conductive member, an elongated winding insulated from but electrically coupled along a major portion of its lengtheto said conductive member for providing a distributed capacitance in said network, a longitudinally-slotted conductive member supported in substantially coaxial relationship with respect to said winding and insulated from but electrically coupled along its length thereto to comprise a condenser, and a conductor connected to said slotted member and to said winding for bridging said condenser across a preselected number of winding turns, said slotted member having such longitudinal length and said conductor being so connected with said winding that said condenser produces in response to an applied signal pulse and superimposed on the delayed pulse output a short pulse occurring ahead of the leading edge of said delayed pulse by a predetermined time interval.

3. A time-delay network for translating a signal pulse comprising, an elongated conductive member, an elongated winding insulated from but electrically coupled along a major portion of its length to said conductive member for providing a distributed capacitance in said network, a longitudinally-slotted conductive member disposed around said winding intermediate the ends thereof and insulated from but electrically coupled along its length to said winding to comprise a condenser, and a conductor connected to said slotted member and to said winding for bridging said condenser across a preselected number of winding turns, said slotted member having such longitudinal length and said conductor being so connected with said winding that said condenser produces in response to an applied signal pulse and superimposed on the delayed pulse output a short pulse occurring ahead of the leading edge of said delayed pulse by a predetermined time interval.

4. A time-delay network for translating a signal pulse comprising, an elongated conductive member, an elongated winding insulated from but electrically coupled along a major portion of its length to said conductive member for providing a distributed capacitance in said network and having input and output terminals, a longitudinally-slotted conductive member supported in substantially coaxial relation with reference to said winding intermediate the ends thereof and insulated from but electrically coupled along its length thereto to comprise a condenser, and a conductor connecting said slotted member to said input terminal for bridging said condenser across a preselected number of winding turns, said slotted member having such longitudinal length and being so spaced along said winding that said condenser produces in response to an applied signal pulse and superimposed on the delayed pulse output a short pulse occurring ahead of the leading edge of said delayed pulse by a predetermined time interval.

5. A time-delay network for translating a signal pulse comprising, an elongated conductive member, an elongated winding insulated from but electrically coupled along a major portion of its length to said conductive member for providing a distributed capacitance in said network, a longitudinally-slotted conductive ring supported in substantially coaxial relationship with respect to said winding and insulated from but electrically coupled along its length thereto to comprise a condenser, and a conductor connected to said slotted ring and said winding for bridging said condenser across a preselected number of winding turns, said slotted ring having such longitudinal length and said conductor being so connected with said winding that said condenser produces in response to an applied signal pulse and superimposed on the delayed pulse output a short pulse occurring ahead of the leading edge of said delayed pulse by a predetermined time interval.

6. A three-terminal time-delay network for translating a signal pulse comprising, an elongated conductive core member, an elongated winding insulated from but electrically coupled along a major portion of its length to said conductive member for providing a distributed capacitance in said network and having a substantial inductive coupling between turns tending to produce a transient distortion pulse in response to an applied signal pulse, and a condenser bridged across a preselected number of turns of said winding, the value of said condenser and the number of said preselected turns being so chosen as to produce in response to said applied signal pulse and superimposed on the delayed pulse output a short pulse comparable in amplitude but opposite in polarity to said distortion pulse and occurring ahead of the leading edge of said delayed pulse in substantial coincidence with said distortion pulse.

7. A four-terminal time-delay network for translating a signal pulse comprising, a pair of elongated and concentrically arranged windings insulated from but electrically coupled along a major portion of their lengths to one another for providing a distributed capacitance in said network and having a substantial inductive coupling between turns tending to produce a transient distortion pulse in response to an applied signal pulse, and a condenser bridged across a preselected number of turns of one of said windings, the value of said condenser and the number of said preselected turns being so chosen as to produce in response to said applied signal pulse and superimposed on the delayed pulse output a short pulse comparable in amplitude but opposite in polarity to said distortion pulse and occurring ahead of the leading edge of said delayed pulse in substantial coincidence with said distortion pulse.

8. A time-delay network for translating a signal pulse comprising, an elongated conductive member, an elongated winding insulated from but electrically coupled along a major portion of its length to said conductive member for providing a distributed capacitance in said network and having a substantial inductive coupling between turns tending to produce a plurality of transient distortion pulses in response to an applied signal pulse, and a corresponding plurality of condensers individually bridged across preselected numbers of turns of said winding, the individual values of said plurality of condensers and the individual numbers of said preselected turns being so chosen as to produce in response to said applied signal pulse and superimposed on the delayed pulse output a like plurality of pulses comparable in amplitude but opposite in polarity to said distortion pulses and occurring ahead of the leading edge of said delayed pulse in substantial coincidence with said distortion pulses.

9. A four-terminal time-delay network for translating a signal pulse comprising, a pair of elongated and concentrically arranged windings insulated from but electrically coupled along a major portion of their lengths to one another for providing a distributed capacitance in said network and having a substantial inductive coupling between turns tending to produce a pair of transient distortion pulses of opposite polarity in response to -an applied signal pulse, a first condenser bridged across preselected points of one of said windings, and a second condenser bridged across preselected points of said pair of windings, said condensers having such values and being bridged between such preselected points of said windings as to produce in response to said applied signal pulse and superimposed on the delayed pulse output a pair of short pulses comparable in amplitude but opposite in polarity to said distortion pulses and occurring ahead of the leading edge of the said delayed pulse in substantial coincidence with said distortion pulses.

10. A four-terminal timedelay network for translating a signal pulse comprising, a pair of elongated and concentrically arranged windings insulated from but electrically coupled along a major portion of their lengths to one another for providing a distributed capacitance in said network and having a substantial inductive coupling between turns tending to produce a transient distortion pulse in response to an applied signal pulse, a first condenser bridged across a preselected number of turns of one of said windings, and a second condenser similar to said first condenser and bridged across the corresponding turns of the other of said windings, the value of said condensers and the number of said preselected turns being so chosen as to produce in response to said applied signal pulse and superimposed on the delayed pulse thereof a short pulse comparable in amplitude but opposite in polarity to said distortion pulse and occurring ahead of the leading edge of said delayed pulse in substantial coincidence with said distortion pulse.

11. A time-delay network adapted to translate a signal pulse the duration of which may be less than the delay of the network comprising, an elongated conductive member, an elongated winding having a substantial inductive coupling between turns tending to cause asymmetrical distortion in one sense of an applied symmetrical pulse and insulated from but electrically coupled along a major portion of its length to said conductive member for providing a distributed capacitance in said network, and a condenser bridged across a preselected number of turns of said winding tending to cause asymmetrical distortion in a complementary sense of an applied symmetrical pulse, the value of said condenser and the number of the said preselected turns being so chosen that an applied symmetrical pulse is translated through said network with a distortion that is substantially less than the larger of said asymmetrical distortions caused'by said inductive coupling and said bridging condenser respectively.

12. A time-delay network adapted to translate a signal pulse the duration of which may be less than the delay of the network comprising, an elongated conductive member, an elongated winding having a substantial inductive coupling between turns tending to cause asymmetrical distortion in one sense of an applied symmetrical pulse and insulated from but electrically coupled along a major portion of its length to said conductive member for providing a distributed capacitance in said network, and a condenser bridged across a preselected number of turns of said winding tending to cause asymmetrical distortion in a complementary sense of an applied symmetrical pulse, the value of said condenser and the number of said preselected turns being so chosen that an applied symmetrical signal is translated through said network with substantially none of said asymmetrical distortions caused by said inductive coupling and said bridging condenser respectively.

13. A time-delay network adapted to translate a signal pulse the duration of which may be less than the delay of the network comprising, an elongated conductive member, an elongated winding having a substantial inductive coupling between turns tending to produce a negative leading echo of an applied pulse and insulated from but electrically coupled along a major portion of its length to said conductive member to provide a distributed capacitance in said network, and a condenser bridged across a preselected number of turns of said winding tending to produce a positive and compensating leading echo of an applied symmetrical pulse, the value of said condenser and the number of said preselected turns being so chosen that a symmetrical pulse is translated through said network with substantially none of said echoes caused by said inductive coupling and the said bridging condenser respectively.

MICHAEL J. DI TORO.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,211,942 White Aug. 20, 1940 2,227,052 White Dec. 31, 1940 Certificate of Correction Patent No. 2,457,212. December 28, 1948. MICHAEL J.. DI TORO It is hereby certified that errors appear in the printed specification of the above numbered patent requiring correction as follows:

Column 3, line 17, for the word especially read speczlficallw-column 8, line 35, for 3 inch. read .8 inch;

and that the said Letters Patent should be read with these corrections therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 21st day of June, A. D. 1949.

THOMAS F. MURPHY,

Assistant Commissioner of Patents.

Certificate of Correction Patent No. 2,457,212. December 28, 1948. MICHAEL J., DI TORO It is hereby certified that errors appear in the printed specification of the above numbered patent requiring correction as follows:

Column 3, line 17, for the word especially read specificallw-column 8, line 35, for 3 inch. read .3 inch;

and that the said Letters Patent should be read with these corrections therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 21st day of June, A. D. 1949.

THOMAS F. MURPHY,

Assistant Uommissioner of Patents.

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