US1816599A - Signal transmission system - Google Patents

Signal transmission system Download PDF

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Publication number
US1816599A
US1816599A US350971A US35097129A US1816599A US 1816599 A US1816599 A US 1816599A US 350971 A US350971 A US 350971A US 35097129 A US35097129 A US 35097129A US 1816599 A US1816599 A US 1816599A
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US
United States
Prior art keywords
volume
level
range
signals
circuits
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
US350971A
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English (en)
Inventor
Robert C Mathes
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
Application filed by Bell Telephone Laboratories Inc filed Critical Bell Telephone Laboratories Inc
Priority to US350971A priority Critical patent/US1816599A/en
Priority to GB37773/29A priority patent/GB344523A/en
Priority to DEE40420D priority patent/DE577222C/de
Priority to FR689561D priority patent/FR689561A/fr
Application granted granted Critical
Publication of US1816599A publication Critical patent/US1816599A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
    • H04B1/62—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission for providing a predistortion of the signal in the transmitter and corresponding correction in the receiver, e.g. for improving the signal/noise ratio
    • H04B1/64—Volume compression or expansion arrangements

Definitions

  • This invention relates to signal transmission systemsv and particularly to circuits for controlling the energy levels in transmission systems.
  • VOne object of the invention lis to provide a signal transmission system with improved means forl and method of maintaining a constant maximum peak energy level and compressing the volume range of the siglo'nalsat the transmitting station.
  • Another object of the invention is to provide a signal transmission system, having signals of substantially the same volume range and different average levels supplied 15to the transmitting station, with means that shall maintain a constant maximum peak energy level and compress the volume range of the signals at the transmitting station.
  • ⁇ ⁇ A further object of the invention is to prov2o ⁇ vide a signal transmission system of the above indicated character that shall maintain a constant maximum peak energy level and compress the volume range of the sigg 4nals at the transmitting station andv that shall expand the volume range of the signals at the receiving station.
  • signals which have very different average volume u levels are 1n many cases received atA the transmitting station.V
  • the significant inomentary volume range in most casesvisfsubstantially the same but may vary.
  • the difference in the average volume level of theY i received signals may be caused by toll lines4 in telephone systems of different electrical lengths and by Vspeakers who talk loudly and softly.
  • lVhenl a telephone system is connected to a radio system suchl as in the trans-Atlantic.
  • a volume control circuit may be defined as a circuit which is adapted toV maintain at a particular point in a system a constant maximum peak level of power regardless of the level at which the speech f power may be received at that particular point in the system.
  • a volume compression circuit may bevdefined as a circuit adapted to reduce the momentary volume range or to reduce the diiference between the maximum peak level and the minimuml significant peak level of signals.
  • the diiliculties produced by reason of the diii'erences in the average volume levels of signals may be reduced either by a volume control system or a volume compression system.
  • the limitations however in some cases may be such that neithera volume control nor a volume compression system will com- Vpletely solve the problem.
  • the volume range ⁇ is compressed according to the limitations of the system. If desired the volume ranges of the different signals may first be compressed and then the signals may be moved to have a constant maximum peak level.
  • Fig. 1 is a .diagrammatic view illustrating theoperation of volume control and volume compleSSOIl llleLnS:
  • Figs. 2 and 3 are diagrammatic views indicating the positions of the volume control means and the volume compression means in different systems..
  • Fig. 4 is a diagrammatic view ofra ⁇ system me ans means included therein, a variable level source VLS comprising conductors 1 and 2 1s connected to an amplilier 3 by meansy of a potentiometer 4.
  • the output ciroull Of the amplifier comprisingconductors 5, and 6 has the output level thereof n'iaintained constant and at a maximum level.
  • Volume control means CM which is connected,to.the output conductors 5 and 6 governsthe operation of the potentiometer 4 the output from the amplifier stant maximumlevel. If the level -inthe output circuit tends to rise, theA control means 'CM operates the potentiometer 4 to govern the amplilier 3 and lower tlielevel in S at aA con- Vthe output circuit. If the level in the out.
  • Fig.. 5 of the drawings a system employing means for compressing the volumev range of the transmittery signals.
  • a variable level source com-prisingl conductors 7 and 8 is connected to an amplifier 9.
  • the amplifier 9 is connectedl tothe line conductors 10 and 11 to maintain Vwhich is received by the amplifier 9V fromy the.supplyrcondnctorsf and 8 is'compressed so that the volume range of the signals sup- 80 picd. .to the conductors-101cm; lflislliccdiiccd Referring to Fig.; 6.0i thcwdiioirins.
  • volume4- expanding volume4- expanding
  • mcciisQG'- Thevoluino cxpandingfnieaii'sf
  • tnansmttingastation 1.15 18 to reverse theefunction'performed by; ,the volume compression.meansattli Y, m-tting'station.
  • Thehybridzcoil 23 isfcoi nected to aV receivingcirciit:comprising@ doctors 27 m1111281l
  • a Avchiiiio.compremio system of, the.v type;v shown in, Fig.A y6 is; .come pletely Idisclosed, ⁇ in fr the above .mentio-ned; patciltto R- G, MathcS,.-No.f1,157,729; ier-,vol ume compressionfsystemfis also; disolosedfin;
  • the abscissa represents the variable level input to the systems shown in Figs. 4 and 5; and the ordinates of the diagram represent the output from the two systems shown in Figs. 4 and 5.
  • the ordinates and abscissae are in terms of volume range on any suitable arbitrary scale.
  • the arbitrary scale may be in terms of transmission units corresponding to the ratio of the power supply to the power received in a system or the transmission unit equals 10 log lOl-l-
  • the volume range of the input OP in Fig. 1 depends on a number of factors.
  • the useful modulation range received from different types of toll circuits will ordinarily never be less than about 2O transmission units.
  • the lengths OM and NP shown in the diagram are considered to vary from 30 to 40 transmission units and each represents the modulation range of speech from a toll circuit.
  • the location of each modulation range of power level may be at a high average level or a low average level, depending upon whether the talker is a person who talks loudly or softly and also upon whether he is talking over a short or long subloop.
  • the difference in level due to whether or not the talker speaks loudly or softly may be from 25 to 30 transmission units.
  • the difference in level due to the electrical length of the toll circuit may be about 10 to 15 transmission units.
  • control range OM may indicate the range of a weak talker on a long loop circuit
  • distance NP may indicate the volume range of a loud talker on a short loop. If the input level range of OP were applied to a volume control system, the output level would be indicated by the straight line at 45o marked OC to produce an output OR.
  • Incase volume control means as shown in Fig. 4 of the drawings is used for controlling an input OP as shown in Fig. 1 of the drawings, the volume range OM of the weak talker over a long loop circuit would be raised to the level of the strong talker over a short loop circuit.
  • the line OM may be assumed to belmoved towards the right to coincide with the line NP. ⁇
  • the weak and loud talkers have the same maximum level which is indicated on the 45 lineby the receiving station, is equal to the transmission units indicated by the distance OR.
  • variable input indicated by the line OP is applied to a system including volume compression means, as shown in Fig. 5 of the drawings, the linear system considered with respect to the 45 line OO in Fig. 1 of the drawings will be replaced by some other characteristic, for example, indicated by the dotted linev OUF.
  • the new characteristic it is desirable to make the new characteristic a straight line as, for example, the line ODEF.
  • the volume range of a weak talker is assumed to be indicated by the line OM as above set forth, the volume range for a loud talker being indicated by the distance NP.
  • the volume range of a weak talker after passing through the volume compression circuits will be reduced to the range OW and the volume range of the loud talker will be reduced to the range TS as indicated on the diagrams shown in Fig. 1.
  • the volume ranges OW and TS in the output are obtained b applying volume ranges OM and NP to t e characteristic line ODEF. Y Assuming that both the volume control and the volume compression circuits operate in the most ideal fashion, a choice of one system as compared with the other systeml will depend on whether the overall compression range is greater or less than the useful modulation speech level of a single talker.
  • the volume range to be transmitted when volume compression circuits are employed is indicated by the distance OS in Fig. 1 of the drawings and the volume range to be transmitted when volume control circuits are employed is indicated by the distance OR.
  • the distance OS is greater or less il.
  • volume control In many cases where the restrictions of the transmission system are very severe, it Iii may be impossible to obtain the most ideal transmission by using either volume control or volume compression means.
  • volume lcontrol and method which consists in moving the average volume levels of the received signals to maintain a maximum peak level in the received signals, in changing the transmitted signals to a reduced and the same volume range, and in expanding the signals at the receiving station.
  • the method which consists in first controlling and then compressing the volume range.

Landscapes

  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Reduction Or Emphasis Of Bandwidth Of Signals (AREA)
  • Selective Calling Equipment (AREA)
US350971A 1929-03-29 1929-03-29 Signal transmission system Expired - Lifetime US1816599A (en)

Priority Applications (4)

Application Number Priority Date Filing Date Title
US350971A US1816599A (en) 1929-03-29 1929-03-29 Signal transmission system
GB37773/29A GB344523A (de) 1929-03-29 1929-12-09
DEE40420D DE577222C (de) 1929-03-29 1929-12-29 Signaluebertragungssystem
FR689561D FR689561A (fr) 1929-03-29 1930-02-07 Perfectionnement aux systèmes de transmission

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US350971A US1816599A (en) 1929-03-29 1929-03-29 Signal transmission system

Publications (1)

Publication Number Publication Date
US1816599A true US1816599A (en) 1931-07-28

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Family Applications (1)

Application Number Title Priority Date Filing Date
US350971A Expired - Lifetime US1816599A (en) 1929-03-29 1929-03-29 Signal transmission system

Country Status (4)

Country Link
US (1) US1816599A (de)
DE (1) DE577222C (de)
FR (1) FR689561A (de)
GB (1) GB344523A (de)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6059108A (en) * 1998-10-30 2000-05-09 Schiltz, Jr.; Richard Wrench organizer for a toolbox

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2539593A (en) * 1945-07-18 1951-01-30 Rines Robert Harvey Electroacoustic system

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6059108A (en) * 1998-10-30 2000-05-09 Schiltz, Jr.; Richard Wrench organizer for a toolbox

Also Published As

Publication number Publication date
FR689561A (fr) 1930-09-09
DE577222C (de) 1933-05-30
GB344523A (de) 1931-03-09

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