US2184826A - Signal transmission system - Google Patents

Signal transmission system Download PDF

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Publication number
US2184826A
US2184826A US174378A US17437837A US2184826A US 2184826 A US2184826 A US 2184826A US 174378 A US174378 A US 174378A US 17437837 A US17437837 A US 17437837A US 2184826 A US2184826 A US 2184826A
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US
United States
Prior art keywords
frequency
carrier frequency
carrier
ringing signal
ringing
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
US174378A
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English (en)
Inventor
Wiessner Alfred
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.)
Alcatel Lucent Deutschland AG
C Lorenz AG
Original Assignee
Standard Elektrik Lorenz AG
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 Standard Elektrik Lorenz AG filed Critical Standard Elektrik Lorenz AG
Application granted granted Critical
Publication of US2184826A publication Critical patent/US2184826A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • 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 high-frequency current systems for intelligence exchange, particularly to systems employing transmission over wires or cables.
  • Such carrier frequency systems transmit the ringing signal as reliably as in a low-frequency intellin gence exchange over lines, for example, by employing impulses of short duration, or a particular tone-frequency.
  • Means must be provided to 'separate the ringing signal from the alternating message currents, and primarily to avoid that the ringing device on'the receiving side be in-Vv fluenced by the message currents.
  • lt is well known to transmit the ringing signal over the communication channel by means of particular tone-frequencies which excite correspondingly tuned relays.
  • vthe drawback of this method is that ringing frequencies may be inu cluded in the alternatingmessage currents whereby undesired excitation of the ringing device may occur.
  • a further known arrangement employs larger amplitudes for the ringing signal than for the message signals, but this measure requires an over-dimensioning of the system, and involves reduced cross-talk attenuation with respect to the other communication channels. Furthermore, this arrangement is inadequate when the line attenuation decreases and the amplitudes of the message signals and the ringing signal assume the same values when the line attenuation increases. Attenuation variations of this magnitude occur in open lines.
  • the carrier frequency is partially or entir-ely suppressed, to utin v lize the carrier itself for effecting the ringing signal.
  • This may, for instance, be obtained by interrupting the carrier frequency according to the rhythm of digital impulses.
  • a tone-frequency may also be transmitted so that the ringing will be eifective only when both of said frequencies prevail.
  • a generator l produces a carrier frequency which is modulated in the modulator 2 by alternating message currents, e. g. speech currents, produced by a device 3.
  • alternating message currents e. g. speech currents
  • carrier frequency is' suppressed either in the modulating device, or by a filter Il which is associated with said modulator.
  • a filter Il which is associated with said modulator.
  • One or two side bands which are passed by the filter t are impressed upon the line a., b over an amplifier E,
  • the ringing signals are produced, e. g. by digital impulses from a 'dial switch and are transmitted in such a manner that the carrier frequency' is vderived from the carrier frequency genera-toi ⁇ over a special line in which a device is included.
  • This device is adapted to interrupt the carrier frequency according to the rhythm of the dialling impulses and, for example, to modulatesaid carrier frequency at a tone-frequency lower than 300 cycles per second.
  • This modulated carrier frequency is also supplied to the line a, b.
  • the lter 4 may be dimensioned so as to have a passing range for the frequencies between (JOBGQ) and (foi2400) cycles per second.
  • the device 6 alsofincludes a filter which for example has a passing range from the carrier frequency to the carrier plus or minus 300 cycles per second.
  • vFor instance if the carrier frequency is interrupted in the device 6 by impulses, or if a digit has been selected by a train of impulses, the carrier frequency and the continuous or interrupted tone frequency Will be supplied to the line a, b and impressed upon the amplifier 'l on the receiving side, where said carrier frequency is amplified and applied to the filtering arrangements 8 and 9.
  • the iiltering arrangement 9 is adapted to pass the carri-er frequency foiSOO cycles per second, while the filtering arrangement 8 has a passing range covering the frequency o-I-SOO .to 2400 cycles per second whereby the speed frequency bandis separated from the ringing signals.
  • the alternating message currents from the iiltering arrangement 8 are applied to a demodulator equipment I0 in any known manner, while the ringing signal from the filtering arrangement 9 is impressed upon a device Il which is adapted to respond e. g. to a frequency lower than 300 cycles per second, or directly to impulses with which the carrier frequency has been modulated,
  • the arrangement according to the invention as above described requires only a single current source for the ringing signal and communica.- tion transmission, whereby the ringing signal and the message currents may be reliably separated in a simple manner.
  • a carrier frequency generator In a high frequency transmission system, a carrier frequency generator, a transmission line, a connection from said generator to one end of said line, a speech frequency modulator and a rst lter in said connection partially at least to suppress the carrier and to lter out all but the side bands above or below the carrier frequency and representing speech frequencies, a.

Landscapes

  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Cable Transmission Systems, Equalization Of Radio And Reduction Of Echo (AREA)
  • Digital Transmission Methods That Use Modulated Carrier Waves (AREA)
US174378A 1936-11-20 1937-11-13 Signal transmission system Expired - Lifetime US2184826A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE492006X 1936-11-20

Publications (1)

Publication Number Publication Date
US2184826A true US2184826A (en) 1939-12-26

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ID=6544348

Family Applications (1)

Application Number Title Priority Date Filing Date
US174378A Expired - Lifetime US2184826A (en) 1936-11-20 1937-11-13 Signal transmission system

Country Status (3)

Country Link
US (1) US2184826A (fr)
FR (1) FR829462A (fr)
GB (1) GB492006A (fr)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2600226A (en) * 1947-04-29 1952-06-10 Hartford Nat Bank & Trust Co Device to minimize interference between dial impulses in a carrier system
US2883464A (en) * 1953-02-18 1959-04-21 Ericsson Telefon Ab L M Device for signal receivers
US3131352A (en) * 1959-12-24 1964-04-28 Philips Corp Transmitting device
US3491207A (en) * 1965-10-07 1970-01-20 Superior Continental Corp Subscriber's two-wire line including carrier telephone communication system

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2600226A (en) * 1947-04-29 1952-06-10 Hartford Nat Bank & Trust Co Device to minimize interference between dial impulses in a carrier system
US2883464A (en) * 1953-02-18 1959-04-21 Ericsson Telefon Ab L M Device for signal receivers
US3131352A (en) * 1959-12-24 1964-04-28 Philips Corp Transmitting device
US3491207A (en) * 1965-10-07 1970-01-20 Superior Continental Corp Subscriber's two-wire line including carrier telephone communication system

Also Published As

Publication number Publication date
GB492006A (en) 1938-09-13
FR829462A (fr) 1938-06-28

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