US2330612A - Subscriber's station for carrier frequency communication systems - Google Patents

Subscriber's station for carrier frequency communication systems Download PDF

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Publication number
US2330612A
US2330612A US367415A US36741540A US2330612A US 2330612 A US2330612 A US 2330612A US 367415 A US367415 A US 367415A US 36741540 A US36741540 A US 36741540A US 2330612 A US2330612 A US 2330612A
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United States
Prior art keywords
line
microphone
winding
transformer
station
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Expired - Lifetime
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US367415A
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English (en)
Inventor
Nitz Herbert
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Individual
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Individual
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Publication of US2330612A publication Critical patent/US2330612A/en
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04J—MULTIPLEX COMMUNICATION
    • H04J1/00—Frequency-division multiplex systems
    • H04J1/02—Details
    • H04J1/08—Arrangements for combining channels
    • H04J1/085—Terminal station; Combined modulator and demodulator circuits
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04M—TELEPHONIC COMMUNICATION
    • H04M1/00—Substation equipment, e.g. for use by subscribers
    • H04M1/78—Circuit arrangements in which low-frequency speech signals proceed in one direction on the line, while speech signals proceeding in the other direction on the line are modulated on a high-frequency carrier signal

Definitions

  • Telephone systems which have means for switching subscribers stations to a carrier frequency four-wire terminal circuit, one
  • a repeater coil or transformer which allows unidirectional currents to pass through it is employed for connecting the microphone to the line, whereby the alternating current resistance of the microphone is matched to the line.
  • FIG. 1 is a diagram showing one embodiment of the invention
  • Fig. 2 is a diagram representing a modification of this embodiment.
  • l and 2 are terminals over which the subscribers station circuit is connected to the subscribers line.
  • B is the usual bridging repeater coil, the secondary winding of which is connected to the receiver over terminals 3 and 4 for ordinary two-wire operation.
  • the coil B is not used the receiver being connected in known manner to the terminals I and 2 over a demodulator and a highpass filter.
  • the microphone M is coupled to the line by an additional matching repeater coil or transformer U having split primary and secondary windings the halves of both windings being connected together over a common condenser C.
  • the direct current supplied from the line for feeding the microphone M flows from line terminal I over the upper half of the primary winding of transformer U and the upper half of the secondary winding to the microphone M and thence over the lower halves of the secondary and primary windings to the line terminal 2.
  • the alternating current component flows through the two halves of the secondary and primary windings interconnected in series by the condenser C and .the transformer Uithus actstoxmatch the alternating current resistance of the microphone M to the line.
  • the repeater coils U and B of Fig. 1 are combined in a single three-winding transformer B in such manner that in the normal two-wire circuit this transformer acts as a. bridging transformer whereas in the carrier frequency four-wire circuit it acts as a matching transformer which at the same time permits direct current to flow to the microphone M.
  • Switch contacts 2' are provided for converting the subscribers substation circuit alternatively either fornormal two-wire working or for use with a carrier frequency fourwire terminal, the contacts being shown in the position for the last-mentioned method of operation.
  • the centre winding 0', d and the right-hand winding of the repeater coil or transformer B are connected in :a bridge connection for two-wire operation, the resistance R being connected in series with the line and serving for bridge balance andthe microphone M being connected between line terminal I and the upper end of the lower half of the centre winding 0, d.
  • the receiver is connected to terminals 3 and 4.
  • the lefthand winding and the centre winding 0', d of the transformer B function as a repeater coil to couple the microphone M to the line for operation with a four-wire terminal in the same manner as the transformer U of Fig. 1.
  • the righthand winding is not used, the receiver being connected to line over a demodulator and highpass filter.
  • the additional portion 0, c of the centre winding is arranged tobe connected in circuit when the upper contacts 2' are closed for two-wire operation. This is for the purpose of obtaining a correct impedance match in the two switching positions, that is, in the position for normal two-wire operation, between the line and the telephone receiver, and in the position for carrier frequency operation between the line and the microphone.
  • the novel arrangement as compared with arrangements having the microphone coupled directly to the line acts to decrease the attenuation by about 2.6 decibels.
  • a subscribers line and a subscribers station circuit comprising a microphone and a transformer for coupling said microphone to said subscribers line, said transformer having split primary and secondary windings, connections between one end of each half of said split primary winding and the said subscribers line, connections between one end of each half of said split secondary winding and said microphone, and a condenser connected between the other ends of the two halves of the said primary winding and the other two halves of the said secondary winding.
  • a subscribers station circuit further comprising a receiver, a tertiary winding on said transformer for. coupling said i receiver to said subscribers line, additional turns on said primary winding, and'switching means for connecting said primary winding across said subscribers line with or without said additional turns in circuit for the purpose of effecting an impedance match between said receiver and said line or between said microphone and said line asidesired'.
  • I 31in a. telephone system, a subscribersrline 20 saidmicrophone and said line and a subscribers station circuit comprising a microphone and a transformer for coupling said microphone to said subscribers line, said transformer having split primary and secondary windings, connections bet-ween one end of each half of said split primary winding and the said subscribers line, connections between one end of each half of said split secondary winding and said microphone, and a condenser interconnecting the two halves of the said primary winding and the two halves of the said secondary winding, a receiver, a tertiary winding on said transformer for coupling.

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  • Engineering & Computer Science (AREA)
  • Signal Processing (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Cable Transmission Systems, Equalization Of Radio And Reduction Of Echo (AREA)
US367415A 1939-12-08 1940-11-27 Subscriber's station for carrier frequency communication systems Expired - Lifetime US2330612A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE219526X 1939-12-08

Publications (1)

Publication Number Publication Date
US2330612A true US2330612A (en) 1943-09-28

Family

ID=5831924

Family Applications (1)

Application Number Title Priority Date Filing Date
US367415A Expired - Lifetime US2330612A (en) 1939-12-08 1940-11-27 Subscriber's station for carrier frequency communication systems

Country Status (5)

Country Link
US (1) US2330612A (no)
BE (1) BE439763A (no)
CH (1) CH219526A (no)
FR (1) FR868502A (no)
NL (1) NL56647C (no)

Also Published As

Publication number Publication date
FR868502A (fr) 1942-01-05
CH219526A (de) 1942-02-15
BE439763A (no)
NL56647C (no)

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