US2142316A - Multiplex multiline carrier system - Google Patents

Multiplex multiline carrier system Download PDF

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Publication number
US2142316A
US2142316A US159667A US15966737A US2142316A US 2142316 A US2142316 A US 2142316A US 159667 A US159667 A US 159667A US 15966737 A US15966737 A US 15966737A US 2142316 A US2142316 A US 2142316A
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United States
Prior art keywords
frequency
group
kilocycles
line
carrier
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
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US159667A
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English (en)
Inventor
George H Huber
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AT&T Corp
Original Assignee
Bell Telephone Laboratories Inc
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Filing date
Publication date
Priority to NL54983D priority Critical patent/NL54983C/xx
Application filed by Bell Telephone Laboratories Inc filed Critical Bell Telephone Laboratories Inc
Priority to US159667A priority patent/US2142316A/en
Priority to GB21076/38A priority patent/GB517036A/en
Priority to FR842226D priority patent/FR842226A/fr
Application granted granted Critical
Publication of US2142316A publication Critical patent/US2142316A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04J—MULTIPLEX COMMUNICATION
    • H04J1/00—Frequency-division multiplex systems
    • H04J1/02—Details
    • H04J1/12—Arrangements for reducing cross-talk between channels
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04J—MULTIPLEX COMMUNICATION
    • H04J1/00—Frequency-division multiplex systems
    • H04J1/02—Details
    • H04J1/14—Arrangements providing for calling or supervisory signals

Definitions

  • the present invention relates to multiplex carrier transmission and particularly to the terminal circuits for translating the voice frequency waves to the high frequency waves for the individual carrier channels and vice versa.
  • cross-talk can be reduced by staggering or interleaving the channel frequencies on neighboring pairs so that the frequencies on one pair coincide with the spaces between channel frequencies on an adjacent pair. Where more than twoI lines are to be used adjacent one another the frequency arrangement becomes more..
  • any one of several frequency arrangements or patterns can be used with terminal circuits which are identical except for the frequency of a wave which is used to shift the frequency of an entire group of waves just before they are applied to the multiplex line or as they are received from the multiplex line.
  • This difference requires merely the use of a particular selective circuit in most cases since the frequency-shifting waves are generated in a common circuit involving production of harmonics of a single base frequency wave.
  • Fig, 1 shows a block schematic form the layout of the terminal circuits for four multiplex lines by way of example and Fig. 2 shows in greater detail in schematic form the modulating and demodulating circuits of one complete channel of one line.
  • Fig. l four multiplex carrier lines are shown at the right of the drawing labeled carrier lines l to 4 and all terminating at the west terminal shown generally in this figure. Twelve channels comprising a lower group of frequencies transmit west to east over each carrier line and twelve channels comprising a higher group of frequencies transmit east to west over each carrier line. From the frequencies marked on the drawing it will be observed that a staggered relation is used from line to line. In the case of the lower group two different frequency arrangements are used comprising frequencies 36 to 84 kilocycles, with one inverted with respect to the other. In the upper groups where the cross-talk problem is more severe because of the higher frequences, fcur different frequency arrangements for the four different lines are used.
  • the upper group comprises frequencies from 92 to 140 kilocycles.
  • the upper group of carrier line 2 uses frequencies from 95 to 143 kilocycles.
  • the upper group of carrier line 3 uses frequencies from 93 to 141 kilocycles.
  • the upper group of carrier line 4 uses frequencies from 94 to 142 kilocycles.
  • the spacing between the individual channel carrier frequencies is four kilocycles and it is understood that the side-band width of each channel is 3000 cycles representing speech waves from 200 to 3200 cycles.
  • the frequency order within the channels is in some cases inverted, that is, the frequencies in the channel are either in the same order as they occur in speech or they are in inverse order.
  • This is represented in the drawing by showing the width of the channel band by a heavy horizontal dash with a short vertical mark at one end. Where the vertical mark is at the left end of the dash it indicates a normal frequency order and where it is at the right-hand end of the dash it represents an inverted order. Since the maximum speech energy occurs in the region below 1000 cycles, an advantage from the cross-talk standpoint is obtained by inverting the frequencies in some cases, as well as staggering them in order to determine the most advantageous relative frequency positions of the speech band spectra on the neighboring lines.
  • Line L-I is one of a group of twelve similar lines only one of which has been shown to avoid undue complication of the drawing.
  • line L2, L-3 or I r-4 is in each case one of a group of twelve similar lines.
  • is typical is provided with a hybrid coil H and balancing network N to provide a transmitting branch I2 and a receiving branch I3.
  • the transmitting branch I2 leads to a modulator I0 for producing a speech modulated wave.
  • receiving branch I3 leads from a demodulator I I for deriving speech waves from received carrier waves and supplying the demodulated waves to the line L-I.
  • modulator IIJ is one of a group of twelve modulators and demodulator II is one of a group of twelve demodulators which would be associated in pairs with twelve voice frequency lines similar to line L-l.
  • modulators I0 atd demodulators II are arranged to be supplied with suitable carriers, that the unmodulated carrier component is suppressed and that only the lower side-band of the modulated wave is utilized as will be disclosed more in detail in connection with Fig. 2.
  • the carrier frequencies that are supplied to the twelve modulators I0 range in frequency from 64 to 108 kilocycles at four kilocycle intervals. A similar range of frequencies is impressed on the demodulators I I.
  • Twelve modulated waves from modulators IIJ are impressed in common on group modulator 20 where they are stepped up in frequency by 340 kilocycles supplied through filter
  • the output of group modulator 20, therefore, comprises twelve channels which have been stepped up to the range of 400.to 448 kilocycles and these are impressed on the second group modulator 30 where they combine with a frequency of 484 kilocycles supplied over circuit 60 from the common frequency supply 'I0 and selectively transmitted through lter 6
  • group modulator ⁇ 30 the twelve channels are stepped down to occupy a frequency range of 36 to 84 kilocycles which is selectively passed by the line filter 40, a low-pass filter, to carrier line
  • the upper group of frequencies in a range of 92 to 140 kilocycles received over carrier line I is selectively passed through line filter 1
  • comprises frequencies from 400 to 448 kilocycles which are impressed on group demodulator El. They combine in demodulator 2
  • the twelve modulators IIJ separately modulate twelve carrier waves of frequencies 64 to 108 kilocycles, respectively, and their outputs are impressed on group modulator 22 in the same way as described for carrier line I.
  • a frequency of 340 kilocycles is supplied to group modulator 22 resulting in an output frequency range the same as in the previous case.
  • the second group modulator 32 is supplied with a wave of a frequency of 364 kilocycles selected by filter 63 from carrier supply circuit 60 so that the twelve channels outgoing to the carrier line 2 range in frequency from 36 to 84 kilocycles and have their frequency orders inverted.
  • the upper group comprises the range to 143 kilocycles which are modulated in group modulator 33 by combining them with a wave of 543 kilocycles selected by filter 64 from the common supply circuit.
  • the output of modulator 33 embraces the same frequency range as the output of modulator 3
  • Group demodulator ⁇ 23 is supplied with a wave of 340 kilocycles and the output comprises twelve individually modulated waves of the same ranges of frequencies as in the case of demodulator 2
  • filters for selectively passing the output of the first stage grouping modulator either transmitting or receiving can all be identical.
  • the receiving group modulator 35 of carrier line 3 is supplied with a wave frequency of 541 kilocycles selectively passed by filter 66; while receiving first group modulator 31 of carrier line 4 is supplied by the wave of 306 kilocycles selected by filter 68 from the common frequency supply '10.
  • the only apparatus of individual design required for the different frequency patterns are the filters 6
  • the common carrier supply circuits may involve a base frequency wave of 4 kilocycles with a harmonic generator for deriving the required harmonic frequencies of the base Wave in a manner well understood in the art.
  • the three non-harmonic frequencies, 306 kilocyclesy 541 and 543 kilocycles, may be derived in any of several ways. As an example for illustration, three separate oscillators 93, 95 and 9110i respectively '7, 6 and 5 kilocycle frequency are used together with modulators 92, 94 and 98 and filters SI and 96 as indicated. Filter 9
  • the 548 kilocycle wave modulates .at 98 with 5 kilocycles from 91 to give 543 kilocycles.
  • Filter 96 selects harmonic frequency 300 kilocycles which modu- TIT lates at 94 with 6 kilocycles from 95 to produce 306 kilocycles.
  • Filter 64, 68 and 68 select the wanted frequencies.
  • the frequency supply circuit may be common to several groups of carrier lines.
  • a low frequency line such as L-I
  • carrier line I Low frequency line L
  • the transmitting branch I2 is shown leading through repeating coil Il to the modulator I l) which may be of a type disclosed and claimed in United States patent to F. A. Cowan 1,959,459, May 22, 1934, comprising four copper oxide rectifiers arranged in the form of a bridge with the speech waves applied across one diagonal and the carrier waves applied across the other diagonal as shown.
  • Such a modulator when properly balanced suppresses the unmodulated carrier component.
  • the lower side-band is selected by the band filter 12, the other side-band being suppressed.
  • Resistance pad 'I3 improves the impedance in which the band filter 'I2 is terminated on the side toward modulator I8.
  • Other band filters for the remainder of the group of twelve lines similar to L--I have their outputs connected in parallel with lter 12, two such filters being indicated for illustration at I4 and l5.
  • 2, 14, 15, etc. may advantageously be of the type employing piezoelectric crystals for obtaining sharpselectivity, such iilters being particularly eicient in the range 60 to 108 kilocycles occupied by these twelve side-bands.
  • group modulator 28 which is indicated as of the general type disclosed and claimed in F. A. Cowan Patent 2,025,158, December 24, 1935.
  • This is a double balanced modulator which suppresses the 340 kilocycle component used as the shifting frequency as well as the 60-108 input frequencies and the group filter 'Il selectively passes the range 400 to 448 kilocycles through suitable amplier as indicated to the second group modulator 30 of the same type as modulator 20.
  • Group modulator 30 is supplied at its conjugate terminals with a suitable shifting frequency, in this case 484 kilocycles, which causes the frequencies to be stepped down to the range 36 to 80 kilocycles for transmission over carrier line I. This latter range is selectively passed by the line filter 48 which suppresses the unused upper side-band.
  • selectively passes the frequencies received from carrier line I to the group receiving modulator 3
  • is the same as lter 'I1 and passes the range of 400 to 448 kilocycles.
  • is supplied with a 340 kilocycle wave as indicated and steps the frequencies down to the range of 60 to 108 kilocycles which are selectively passed by filter 82.
  • a carrier signaling system a plurality of lines adjacent one another and having an appreciable cross-talk factor, message input circuits for each line, modulators of interchangeable type for the message input circuits of respective lines, for producing a similar group of messagemodulated carrier waves for each line, interchangeable rst group-modulators for the respective lines for translating the respective groups of message-modulated carrier waves to similar higher frequency bands, interchangeable second group-modulators and frequency supply circuits therefor for stepping the frequencies of the groups of modulated waves downward by a different amount in the case of each line and applying the waves of stepped-down frequency to the respective lines so that the individual messagemodulated waves traversing the lines are interleaved in the frequency spectrum.
  • a carrier signaling system a plurality of carrier lines adjacent one another and having an appreciable cross-talk factor, a receiving station for such lines, each line being traversed by carrier channels some of which are in off-set frequency relation from line to line, group modulators of interchangeable type for the several lines and frequency supply circuits therefor for receiving the channel waves from the respective lines and stepping them upwards in frequency by a different amount where necessary to translate them to the saine high frequency range, interchangeable group-demodulators for the several lines for stepping the frequencies of the groups of channel waves from such high frequency range downward by the same amount, individual interchangeable message demodulators for deriving message waves from the channel waves of stepped down frequency, and line circuits leading from said message demodulators to the eventual receiving points.

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  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Digital Transmission Methods That Use Modulated Carrier Waves (AREA)
  • Cable Transmission Systems, Equalization Of Radio And Reduction Of Echo (AREA)
US159667A 1937-08-18 1937-08-18 Multiplex multiline carrier system Expired - Lifetime US2142316A (en)

Priority Applications (4)

Application Number Priority Date Filing Date Title
NL54983D NL54983C (enrdf_load_stackoverflow) 1937-08-18
US159667A US2142316A (en) 1937-08-18 1937-08-18 Multiplex multiline carrier system
GB21076/38A GB517036A (en) 1937-08-18 1938-07-15 Multiplex multi-line carrier system
FR842226D FR842226A (fr) 1937-08-18 1938-08-17 Système de transmission à ondes porteuses multiplex

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US159667A US2142316A (en) 1937-08-18 1937-08-18 Multiplex multiline carrier system

Publications (1)

Publication Number Publication Date
US2142316A true US2142316A (en) 1939-01-03

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Family Applications (1)

Application Number Title Priority Date Filing Date
US159667A Expired - Lifetime US2142316A (en) 1937-08-18 1937-08-18 Multiplex multiline carrier system

Country Status (4)

Country Link
US (1) US2142316A (enrdf_load_stackoverflow)
FR (1) FR842226A (enrdf_load_stackoverflow)
GB (1) GB517036A (enrdf_load_stackoverflow)
NL (1) NL54983C (enrdf_load_stackoverflow)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2528090A (en) * 1943-09-14 1950-10-31 Punch Engineering Pty Ltd Means for changing the transmission carrier frequencies in multichannel signaling and communication systems
US4845756A (en) * 1986-09-09 1989-07-04 Siemens Aktiengesellschaft Apparatus for through-connecting audio signals

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2528090A (en) * 1943-09-14 1950-10-31 Punch Engineering Pty Ltd Means for changing the transmission carrier frequencies in multichannel signaling and communication systems
US4845756A (en) * 1986-09-09 1989-07-04 Siemens Aktiengesellschaft Apparatus for through-connecting audio signals

Also Published As

Publication number Publication date
FR842226A (fr) 1939-06-08
NL54983C (enrdf_load_stackoverflow)
GB517036A (en) 1940-01-18

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