US2342544A - Submarine cable transmission - Google Patents

Submarine cable transmission Download PDF

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Publication number
US2342544A
US2342544A US439497A US43949742A US2342544A US 2342544 A US2342544 A US 2342544A US 439497 A US439497 A US 439497A US 43949742 A US43949742 A US 43949742A US 2342544 A US2342544 A US 2342544A
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US
United States
Prior art keywords
gain
cable
repeater
band
repeaters
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US439497A
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English (en)
Inventor
Oliver B Jacobs
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
AT&T Corp
Original Assignee
Bell Telephone Laboratories Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority to NL71859D priority Critical patent/NL71859C/xx
Priority to BE471045D priority patent/BE471045A/xx
Application filed by Bell Telephone Laboratories Inc filed Critical Bell Telephone Laboratories Inc
Priority to US439497A priority patent/US2342544A/en
Priority to GB6136/43A priority patent/GB563099A/en
Application granted granted Critical
Publication of US2342544A publication Critical patent/US2342544A/en
Priority to FR941437D priority patent/FR941437A/fr
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B3/00—Line transmission systems
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F1/00—Details of amplifiers with only discharge tubes, only semiconductor devices or only unspecified devices as amplifying elements
    • H03F1/34—Negative-feedback-circuit arrangements with or without positive feedback
    • H03F1/36—Negative-feedback-circuit arrangements with or without positive feedback in discharge-tube amplifiers
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B3/00—Line transmission systems
    • H04B3/02—Details
    • H04B3/04—Control of transmission; Equalising
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B3/00—Line transmission systems
    • H04B3/02—Details
    • H04B3/04—Control of transmission; Equalising
    • H04B3/06—Control of transmission; Equalising by the transmitted signal
    • H04B3/08—Control of transmission; Equalising by the transmitted signal in negative-feedback path of line amplifier

Definitions

  • the present invention relates to deep-sea cable transmission, involving sea-bottom repeaters, or to similar types of transmission.
  • the invention has particular application to the general type of system disclosed and claimed in Buckley-Jacobs Patent.2,020,297, November 12, 1935, in which one or usually many repeaters would be incorporated in a deep-sea cable for reinforcing the signal waves sent over the cable.
  • a broad frequency band accommodating several carrier telephone channels or even a practical television range is contemplated.
  • a sea-bottom system is by circum stances a constant attenuation system since it operates at a constant temperature and, therefore, the resistance of the copper core remains at the same value indefinitely. This fact makes it practical to use constant gain repeaters.
  • a type of repeater which can be made to have a nearly constant insertion gain notwithstanding wide variations in' tube gain is the stabilized feedback repeater disclosed and claimed in H. S. Black Patent 2,102,671, December 21, 1937.
  • the present invention utilizes these stabilized feedback repeaters as sea-bottom repeaters and the design is such as to stabilize the gain as far as possible so as to minimize the effect on repeater gain of the loss of gain by the tubes due to aging or other causes of tube deterioration.
  • the repeater gains are preshaped to take account of the less complete compensation for loss of tube gain in the middle portion of the transmission band so that as the tubes eventually lose gain the departures from best performance due to that cause are kept within narrower limits.
  • Fig. l is a block diagram of one terminal of a two-way deep-sea cable installation of a type to which the invention is applicable byway of example;
  • Fig. 2 shows in simplified schematic diagram the circuit of one repeater in the cable
  • Figs. 3 and 4 show graphs to be referred to in the description.
  • Fig. 1 shows in single line schematic three tele- -channel blocks at present in use in connection with commercial carrier telephony.
  • the sideband filters for separating the various conversational waves from one another are shown at l8 and terminal amplifiers are indicated at IS.
  • the transmitting channels lead into eastward cable 20 via equalizing network 24, amplifier 25 and coupling capacity 22. and thereceiving channels are derived from westward cable 2
  • Each cable has included in its repeaters R at spaced intervals in accordance with the disclosure and teaching of the Buckley-Jacobs patent.
  • Energizing current for these repeaters is supplied over the cables from the two shore ends, one source being indicated at 21 connected to the cable cores through filters indicated by the inductances 28, and through regulating resistances 29.
  • a similar source oppositely poled is at the opposite end. Since the present invention is not In Fig. 3 the solid line curve C is a plot of assumed attenuation characteristic oi! a section of submarine cable leading up to some one repeater R, such as thatin Fig. 2. It is possible by known methods of amplifier design to provide a repeater of the type shown in Fig. 2 whichwill as closely as may be desired.
  • the general meth- 0d of design to be followed for this purpose is that given in H. W. Bode Patents 2,123,178, July 12,
  • Fig. 2 one repeater R inserted between sections of cable 20 is shown as includingthree pentode tube stages 30, 3
  • the cathodes are connected through usual grid bias resistance-condenser circuits to the conductor 4
  • Leads P1 and P2 are connected through resistances to lead 40 for supplying plate and screen voltage to tubes 30 and 3
  • a similar connecton is' made for thescreen of tube 32, the plate of this stage getting its voltage through the beta network.
  • Suitable filtering is supplied to separate the energizing current from the signals, including inductance 43 and capacity 44 at the output side and the constant-resistance bridge or lattice network' composed of inductance 45, capacity 41,
  • the repeater instead of designing the repeater to have a gain characteristic exactly matching the attenuation characteristic of the cable over the band, the match is made at both edges of the band but the gain curve lies slightly above the attenuation curve in the middle portion 01' the band as indicated by the dotted curve marked Initial A.
  • the departure would be less than actually indicated, the showing being greatly exaggerated for illustration.
  • the middle portion of the gain curve will sag and the match between the attenuation and gain curves will be closer.
  • the gain curve will continue to sag in the middle and reach the at the edges a reverse efiect to that described with respect to the middle part of the band takes place, the gains at the extreme edges being made initially slightly less than the cable attenuation and approaching the cable attenuation as the tubes begin to lose gain.
  • Fig. 4 is a level diagram for a cable including a number of repeaters in tandem. It shows in' another way the same eiiects as discussed in connection with Fig. 3.
  • the band edges are at 12 kilocycles and 60 kilocycles while the frequency at which the repeater gain changes most with tube gain is taken as 25 kilocycles.
  • the points of greatest gain stability are at 12 kilocycles and 56 kilocycles. The gains and losses for these three frequencies are plotted. There quency.
  • the signal input levels are higher than at the repeater points to provide adequate margin over the higher noise level nearshore.
  • the repeater gain is shaped to raise'both edges of the band to the same outgoing level for application to the succeeding cable section. This action is repeated at each repeater station throughout.
  • the input level is raised by the operating attendants until it ultimately becomes (for 25 kilocycles) the level indicated by theeurve, 25 kilocycles ultimately.
  • the repeater gains are slightly smaller than the cable attenuations at 25 kilocycles so that the tips of the graph are sloping downwardly toward the right.
  • the last repeater R7 is on shore and may comprise amplifier 26 and compensation network 28' of Fig. 1, so that this repeater is accessible for adjustment. Its gain characteristic is adjusted with time to be greater ultimately than initially at the middle part of the band in order to give an arrival wave that is undistorted for either the initial, ultimate or intermediate conditions discussed.
  • repeaters While for simplicity all repeaters have been assumed alike, it is within the invention to build certain repeaters with special characteristics to have a rectifying eflect on the cumulative characteristic of a number of intervening repeater sections. In laying a cable, for example, it may be desirable every so often to include such a special repeater designed to compensate for measured irregularities in the portion of the system already put down.
  • a repeater such as has been disclosed may have initially a negative feedback of 40 decibels or more throughout the transmission band and the insertion gain at 60 kilocycles may be 60 decibels or higher, these values being given by way of example and not as'limiting.
  • This initial order of magnitude of feedback should be sufficient to reduce the changes in insertion gain to the order of four-tenths of a decibel when the feedback has decreased 15 decibels.
  • a repeater for insertion in a submarine cable comprising a stabilized feedback vacuum tube amplifier, means providing a large enough feedback ratio in said amplifier, to give complete compensation near the edges of the used transmission frequency band for variation in tube gain with aging of tubes, throughout the expected lifeof 'said repeater, and equalizer means in said repeater for shaping the insertion gain frequency characteristic of said repeater to an approximate match of the attenuation frequency characteristic of a section of said cable, said equalizer means causing said match to be practically complete at two frequencies near the two edges of the used trans: mission band but causing the gain characteristic to exceed the attenuation characteristic in the middle portion of the band by an amount equal to about one-half the expected reduction of insertion gain of the repeater in the middle portion of the band due to aging of the tubes over the expected life of said repeater.
  • a vacuum tube amplifier for insertion at a point in said cable, said amplifier having a gain stabilizing feedback of sufliciently great feedback factor to maintain the gain substantially constant throughout a given portion of said transmission frequency band notwithstanding large changes in tube gain, whereby the change in insertion gain within said portion of the transmission frequency band due to tube deterioration with age is reduced to a given small amount over a given period of many years, and shaping means causing said amplifier to have an initial insertion gain throughout said portion of the transmission frequency band in excess of the cable loss by substantially one-half said given small amount to compensate in advance for such deterioration in tube gain over said given period.
  • a submarine cable for transmission of signals occupying aband of frequencies, said cable composed of sections with repeaters inserted between successive sections, said repeaters each having a gain stabilizing feedback of sufficiently great feedback factor to maintain the insertion gain substantially constant with time notwithstanding substantial loss in tube gain, said repeaters having initial gains closely matching the attenuation of the adjacent cable section near the edges of the band but sufficient excess gain in the middle portion of the band to allow for eventual small sagging of insertion gain in the middle portion of the band due to deterioration of the repeater tubes with age.
  • the method of operation comprising predistorting the input waves to maintain the level of waves impressed on said cable substantially constant over the first-mentioned part of the range and to progressively vary the level of waves impressed on said cable over the other-mentioned part of the rangein inverse relation to the changes in repeater gain over that part of the range.
  • the method of controlling transmission comprising initially setting the gains of the repeaters to equal the cable attenuation at or near the edges of the band and 45 to be slightly in excess of the cable attenuation at frequencies within the portion of the band in which the gain is subject to change with time,
  • a repeater for sea-bottom installation in a deep-sea cable comprising a stabilized feedback vacuum tube amplifier having such a. large feedback factor as to maintain the insertion gain substantially constant notwithstanding changes of tube gain, at two stable points coinciding substantially with the edges of the transmission frequency band, and equalizer means in the repeater for sloping the gain frequency characteristic of the repeater to match the loss frequency characteristic of the cable at said two points, said means causing the repeater gain to exceed the cable loss in the middle portion of the band by about one-half the gain reduction of the repeater in the middle portion of the band due to aging of the tubes throughout the assigned life of the repeater.
  • a repeater for insertion in a submarine cable comprising a stabilized feedback discharge tube amplifier, and equalizer means in said repeater for causing the repeater to have a gain frequency characteristic closely matching the attenuation frequency characteristic of the cable at approximately the two edges of the transmission frequency band but at a frequency slightly within the band near at least one edge while lying slightly above the cable characteristic over the main portion of the band and slightly below the cable characteristic at said one edge of the band, by such an amount at each frequency in the band as to offset in part the eventual decrease in repeater gain with time at the various frequencies in the band.

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  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Power Engineering (AREA)
  • Cable Transmission Systems, Equalization Of Radio And Reduction Of Echo (AREA)
  • Amplifiers (AREA)
US439497A 1942-04-18 1942-04-18 Submarine cable transmission Expired - Lifetime US2342544A (en)

Priority Applications (5)

Application Number Priority Date Filing Date Title
NL71859D NL71859C (enrdf_load_stackoverflow) 1942-04-18
BE471045D BE471045A (enrdf_load_stackoverflow) 1942-04-18
US439497A US2342544A (en) 1942-04-18 1942-04-18 Submarine cable transmission
GB6136/43A GB563099A (en) 1942-04-18 1943-04-16 Improvements in or relating to repeaters for submarine cables
FR941437D FR941437A (fr) 1942-04-18 1947-02-08 Répéteur pour câbles sous-marins

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US439497A US2342544A (en) 1942-04-18 1942-04-18 Submarine cable transmission

Publications (1)

Publication Number Publication Date
US2342544A true US2342544A (en) 1944-02-22

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ID=23744941

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Application Number Title Priority Date Filing Date
US439497A Expired - Lifetime US2342544A (en) 1942-04-18 1942-04-18 Submarine cable transmission

Country Status (5)

Country Link
US (1) US2342544A (enrdf_load_stackoverflow)
BE (1) BE471045A (enrdf_load_stackoverflow)
FR (1) FR941437A (enrdf_load_stackoverflow)
GB (1) GB563099A (enrdf_load_stackoverflow)
NL (1) NL71859C (enrdf_load_stackoverflow)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2541811A (en) * 1947-10-10 1951-02-13 Joseph W Crownover Hearing aid amplifier
US2556219A (en) * 1946-03-19 1951-06-12 Int Standard Electric Corp Negative feedback circuit for parallel-connected thermionic amplifiers
US2637784A (en) * 1951-05-31 1953-05-05 Western Union Telegraph Co Means for increasing the telegraph signaling speed of submarine telegraph cables
US6016076A (en) * 1998-06-05 2000-01-18 The Whitaker Corporation Method and apparatus for microwave predistorter linearizer with electronic tuning

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2556219A (en) * 1946-03-19 1951-06-12 Int Standard Electric Corp Negative feedback circuit for parallel-connected thermionic amplifiers
US2541811A (en) * 1947-10-10 1951-02-13 Joseph W Crownover Hearing aid amplifier
US2637784A (en) * 1951-05-31 1953-05-05 Western Union Telegraph Co Means for increasing the telegraph signaling speed of submarine telegraph cables
US6016076A (en) * 1998-06-05 2000-01-18 The Whitaker Corporation Method and apparatus for microwave predistorter linearizer with electronic tuning

Also Published As

Publication number Publication date
NL71859C (enrdf_load_stackoverflow)
GB563099A (en) 1944-07-28
FR941437A (fr) 1949-01-11
BE471045A (enrdf_load_stackoverflow)

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