US1644395A - Transmission system - Google Patents

Transmission system Download PDF

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Publication number
US1644395A
US1644395A US112419A US11241926A US1644395A US 1644395 A US1644395 A US 1644395A US 112419 A US112419 A US 112419A US 11241926 A US11241926 A US 11241926A US 1644395 A US1644395 A US 1644395A
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US
United States
Prior art keywords
sections
characteristic
correcting
transmission system
repeater
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
US112419A
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English (en)
Inventor
Bruno G Pohlmann
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.)
Siemens and Halske AG
Siemens Corp
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Siemens Corp
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Filing date
Publication date
Application filed by Siemens Corp filed Critical Siemens Corp
Application granted granted Critical
Publication of US1644395A publication Critical patent/US1644395A/en
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
    • H04B3/02—Details
    • H04B3/04—Control of transmission; Equalising
    • H04B3/14—Control of transmission; Equalising characterised by the equalising network used
    • H04B3/143—Control of transmission; Equalising characterised by the equalising network used using amplitude-frequency equalisers
    • H04B3/144—Control of transmission; Equalising characterised by the equalising network used using amplitude-frequency equalisers fixed equalizers

Definitions

  • This invention relates to electrical transmission systems and has for its general ob'- ject to compensate for the distortion produced by a long transmission line.
  • the distortion of long telephone lines is eliminated either by using repeaters having amplification characteristics proportioned to compensate for the line distortion o1' by inserting correcting artificial lines having attenuation characteristics complementary to the attenuation of the line in combination with repeaters having substantially flat amplification characteristics. In both cases an overall characteristic which is independent of frequency is desired. Generally the line is divided 'into sections and the distortion in each section is corrected by the corresponding repeater or the equalizer associated therewith. In long.
  • a particular obj ect of this invention is to overcome this difficulty.
  • the-correcting means of the sections comprising the transmission system are made diiferent, the differences being such that the sections are complementary to each other giving an overall transmission characteristic which is substantially inde- 40 pendent of frequency.
  • each of a group of sections is corrected to give an approximately constant 4 5 characteristic and there is associated with one section of thev group anadditional cor-- recting means having such a characteristic as to compensate for the combined discrep ancies of the group.
  • the transmission system is ofv such length that it embodies several groups of sections of similar design the yariations from the. desired characteristic in each group may be' cumulative in a similar manner as In a preferred embodiment of the inven-l the variations in the sections of each group so that it is desirable ⁇ to provide additional means to. compensate for the total. group inaccuracies within the system in the same manner as the total section inaccuracies are compensated in each group. If the system 1s of such length that itis desirable to regroup the grou s this method may be extended still furt er.
  • the repeaters can either be particularly designed so that ends upon the frequency in a manner diferent from the standard repeaters, or else a repeater of the standard type having s ecial associated'corr'ecting means can be use
  • the spacing of the special repeater points is preferably so chosen that the net distortion over the portion of the line therebtween is of the v'same order of magnitude as is ordinarily corrected for with a single network.. In this way apractically complete correction is obtained, even with very gre-at lengths of line. without ⁇ extraordinary demands be ing made upon the correcting means at the special repeater points.
  • ⁇ A limiting case is the one in which the group lconsists of only two sections in which the errors of'correction are so displaced with respect to each otherthat they practically neutralize one another.
  • a transmission system of a large number of sections is then comprised of mere groups of two sections each so that altogetherit'is only necessary to construct two types of correcting means,
  • Fig. 1 shows-graphically the attenuation and amplification characteristic of a single line'section and repeater.
  • Fig. 2 shows graphically the netdistortion in a group of corrected sections and Fig. 3 shows diagrammatically one embodiment of a transmission system according to this invention.
  • Curve b of Fig. l shows the attenuation characteristic of a single repeater section plotted against frequency
  • curve s of the saine figure shows the amplication characteristic of a correcting repeater associated with the same section plotted against frequency. It will ybe noted that the deviationsrof the lamplification curve from the attenuation curve are fairly small giving a characteristic for a single sectionwhich is a proximately lconstant with frequency.l
  • Fi 3 shows a transmission system compose of six line sections 1, 2, 3, 4, "5 and 6' and associated repeaters, 11, 12, 13, 14,
  • This invention is not limited to the particular embodiment shown'ibut may be variously modified; for example, as described generally above. Similar arrangements may also .be used for correcting for phase distor- ⁇ tion or for both phase distortion and attenuation.
  • a transmission system comprising a line of a plurality of groups of sections, at-.
  • a transmission system comprising a multiplicity of tandem sections with amplifying repeaters connectedlbetween successive sections, means as sociatedwith certain repeaters at points along'tlie system for correcting for unequal attenuation of dii'erent frequency components ,transmitted by the system, and means associated with repeaters at points respectively intermediate said eerthe net attenuation of, ⁇ said systemincluding the other repeatersA and'their associated'correcting-means, whereby substantially complete correction is ⁇ madel at a number of' line a pluralityv'of sections apart, correcting for the net distortion lresulting after the first-mentioned correcting steps.

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  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Cable Transmission Systems, Equalization Of Radio And Reduction Of Echo (AREA)
US112419A 1925-05-14 1926-05-29 Transmission system Expired - Lifetime US1644395A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE1644395X 1925-05-14

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US1644395A true US1644395A (en) 1927-10-04

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US (1) US1644395A (enrdf_load_stackoverflow)
BE (1) BE334392A (enrdf_load_stackoverflow)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2444063A (en) * 1944-12-07 1948-06-29 Bell Telephone Labor Inc Electric circuit equalization

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2444063A (en) * 1944-12-07 1948-06-29 Bell Telephone Labor Inc Electric circuit equalization

Also Published As

Publication number Publication date
BE334392A (enrdf_load_stackoverflow)

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