US1343308A

US1343308A - Duplex translating-circuits

Info

Publication number: US1343308A
Application number: US157414A
Authority: US
Inventors: John R Carson
Original assignee: American Telephone and Telegraph Co Inc
Current assignee: AT&T Corp
Priority date: 1916-09-05
Filing date: 1917-03-26
Publication date: 1920-06-15
Anticipated expiration: 1937-06-15

Description

J. R. CARSON.

DUPLEX TRANSLATING CIRCUITS.

APPLICATION FILED MAR.26. 1917. RENEWED MAY 27. 1919.

153435308. Patented June 15, 1920.

4 i I I I I I ,fie 19120 1 Fz' tar INVENTOR ATTORNEY stares JOHN R. CARSON, 0F MONTCLAIR, NEW JERSEY, ASSIGNOR TO AMERICAN TELEPHONE AND TELEGRAPH COMPANY, A CORPORATION OF NEW YORK.

DUPLEX TRANSLATING-CIRCUITS.

raiasos.

Specification of Letters Patent.

Patented June 15, 1920.

Original applicationfiled September 5, 1916, Serial Ito. 118,573. Divided and this application filed March k 26, 1917, Serial No. 157,414. Renewed May 27, 1919. Serial No. 300,180.

To all whoin it may concern:

siding at Montclair, in the county of Essex and State of New Jersey, have invented certain Improvements in Duplex Translating-Circuits, of which theafollowing is a specification.

I The invention of this application, which is a division of application Serial No. 118,- 573, filed September 5th, 1916, relates to signaling circuits and has for its general object the provision of a duplex translating system which is capable of a wide range of utility, and which shall exhibit a high degree of efficiency in thevarious applications of which it is capable.

In its general embodiment the invention comprises a duplex translating structure having a pair of input and a pair of output circuits, the pair of input circuits being symmetrically associated with one source of current variation, and oppositely associated with a second source, the output circuits being differential with respect to one or: receiving circuit and cumula- 1 spect to another outgoing cirthe first mentioned source protue of its symmetrical conneci t1 e fluctuations of the same phase in'the'two input circuits, while the second'mentioned source, by virtue of the I .fact that the input circuits are oppositely associated therewith, produces potential fluctuations of opposing phase in said input circuits. This statement is made to define the significance attached to symmetrical and opposite connections in this specification.

Thus in general there may be four main elements comprising two sources and two receiving circuits which may be variously related to the translating device proper. Additional results may be produced by the omission of one or more of the four main elements, with corresponding changes in the connections of the remaining elements. The form of translating device used may preferably be of the thermionic vacuum tube type,

carrier wave signaling in which the necessity for high frequency tuning and selectivity is eliminated.

The invention will-ebe more fully under stood by reference to the. drawing in which Figures 1, 2, 3 and L illustrate four modifications of a selective receiving system for multiplex carrier currents.

Referring now to F igul, a pair of three element thermionic tubes, having filaments 1, 2,

grids

3, 4, and plates 5, 6, are provided, the filaments being heated by a battery 7. The tubes are preferably similar and equal in their structure and characteristic, and are equivalent to and may be replaced as illustrated in Fig. 4 by a single duplex tube such as is shown in the patent of E. H. Colpitts, 1,128,292, February 16th, 1915. The input circuits of the tubes are arranged in parallel with respect to the secondary of a transformer 68 in the common conductor of the two input circuits.

'The output circuits are also connected in a circuit 62 which terminates in the primary 63 of a transformer 64, having two secondary windings .65 and 66, one included in each of the input circuits of the repeater.

A local source of high frequencyis sup-- plied by a homodyne or heterodyne enerator 67 which is coupled through transormer 68 to the common conductor of the two input circuits. Itwill be understood that a heterodyne generator is a source of alternating current energy of a frequency differing from that of the incoming carrier wave by a pre-assi ned frequency preferably "Within the limits of audition, while a homodyne generator is a source of energy of a frequency'identical with that'of, the" incoming carrier wave. Theformer is employed when unmodulated carrier waves are transmitted, while the latter is preferably employed when the carrier wave is modu- \certain limit, but permit the passage with-" lated as in carrier wave telephony. In each output circuit is inserted a primary wind-' ing of a transformer 69, the winding in circuit with plate 5 being designated and that in circuit with plate 6 being designated 71. The secondary 72 of the transformer'is connected to a circuit 73 leading through a low frequency filter (not shown) to a receiving instrument. -The filter to be used is of a well known type of broad band filter which will suppress all frequencies above a out attenuation of all frequencies below this limit, which for telephonic purposes might be fixed at 2,500 cycles. This typeof filter is disclosed and fully described in U. S. Patent of G. .A. Campbell, No. 1,227,113, issued May 22, 1917.

The operation of the apparatus will be understood from the following considerations:

It has been pointed out in a U. S. patent issued to Maurice LeBlanc, No. 857,079 of June 18, 1907, that when a plurality of carrier currents of different frequencies, each modulated by voice'currents are sent out on ;a line, and at a receiving station afrequency equal to that of one of the carriers is provided, this frequency will interact with the modulated carrier, current having the same period, with the result that a suitable receiving instrument will respond to the low frequency voice currents by which that particular carrier is modulated, while carriers having a different frequency will be without effect. A.- full theoretical discussion of the principles involved is given inthe above patent and need not here be repeated, it being sufficient to point out that if a plurality of carrier waves havingfrequencies f f f be sent out on the line, each modulated at audio frequency p, and further if at the'receiving station a homo dyne frequency f equal to the frequency of one of the carrier waves be allowed to interact therewith, a plurality of frequencies will result in the output circuits of the repeater structure of Fig. 6 as follows:

(f1+fk+2 f1+fk1I (f1f1 +1 (flfk p) (Aura; (am 52 2112 acre. Assuming that the homodyne frequency f is equal to frequency f,,, the last four frequencies reduce to (2f +p),' (2f p), p and p. If the carrier frequencies differ from each other by an amount greater than 279 it will be clear that all of the frequencies above set forth except 3? and- 0 will be greater than 10. Hence a filter .in the outgoing circuit which suppresses all frequencies above 37 will suppress everything except the audio frequency by which carrier frequency 7",. was modulated. 'The signals by which other carriers were modulated w ll not be received because the resultdyne frequency to the common conductor .-1,34 spos ant frequencies due to their interaction with the carrier frequency and the homodyne frequency will be greater than 10. It will now be apparent that by applying the homo-' 70 of the input circuits of Fig. l'through transformer 68, so that this frequency interacts with the several incoming carrier frequencies modulated by low frequency signals, the various resultant frequencies 75 above set forth will appear in the output A circuits of the repeater and be impressed on outgoing circuit 73 through transformer 69, the filter acting to suppress everything except the voice currents which modulated the carrier current having the same frequency as the homodyne generator. The same effect will be produced if the incoming car- -rier currents are impressed upon the transtheincoming line, the energy from the generator does not react upon theline and cause a tone in other receiving devices upon the same line. A further advantage attaching to the use of duplex translating arrangements resides in the fact that distortion' of the incoming signal which is always and inherently caused by ordinary detectors is substantially eliminated by the combination of the duplex detector with a 0 local homodyne generator. Consequently the utility of the duplex detector is not limited to its-use in combination with afilter nor is it limited to use in a multiplex system. t

A slight modification is shown in Fig. 2 in which the incoming carrier currents are impressed upon the input circuits of the duplex detector by a conductive connection instead of by an inductive connection such as shown in Fig. 1. The two sides of the incoming line 74 are directly connected to I the

grids

3 and 4, and are bridged by'substantially

equal resistances

75 and 76, to the mid-point of which the common conductor'l fi of the input circuits of the detector is connected, the homodyne currents being applied jus t as in Fig. 1. The operationis similar'to that already described in connection with Fig. 1. v In Fig. 3 an alternative arrangement is shown in whichthe incoming line 77 is directly connected in the common conductor of the two input circuits of the repeater, while the homodyne currents from gener- -125 ator 67 are applied through a transformer 78, having secondary windings 80 and 81, one in each of the input circuits. The operation of this circuit is similar to that of Figs.

rangements of Figs' 1, 2 and 3 are essentially equivalent and that the particular connections are immaterial although preferably one of the two sources of potential variations should be applied symmetrically or cumulatively and the other oppositely to the two input circuits and the receiving circuit 73 should be differently coupledto the two output circuits. Theinvention is not limited to such an arrangement, however.

It will be seen that by this invention a duplex translating system has been devised which is both simple and efficient and which is capable of a large number of applications to produce widely varying results. While the invention has been illustrated as embodied in a limited number of forms it will be understood that the embodiment may be widely varied without departing from the scope of the appended claims.

What is claimed is:

1. A receiving apparatus for carrier wave signaling systems comprising a pair of translating devices having input and output circuits, a circuit for the reception of high frequenc signals, a second circuit containing a loca source of high frequency energy, one of said circuits being symmetrically associated with said input circuits, and the other being oppositely associated-with said input circuits, and a receiving circuit differentially associated with said output circuits.

2. A receiving apparatus for carrier wave signaling systems comprising a duplex detector arrangement having divided input and divided output circuits, a circuit for the reception of high frequency signals, a second circuit containing a local source of high frequency energy, one of said circuits being symmetrically associated with said input circuits and the other being oppositely associated with said input circuits, and a receiving circuit differentially associated with said output circuits. I

3. A receiving apparatus for carrier wave signaling systems comprising a pair of transv lating devices having input and output circuits, a circuit for the reception of high frequency signals, a second circuit containing a local source of high frequency energy, one of said circuits being symmetrically associated with said input circuits and the other being oppositely associated with said input circuits, a receiving circuit differentially associated with said output circuits, and a filter in said receiving circuit.

4. A receiving apparatus for carrier wave signaling systems comprising a duplex detector arrangement having divided inputand divided output circuits, a circuit for the reception of high frequency signals, a second circuit containing a local source of high frequency energy, one of said circuits being symmetrlcally associated with said input circuits and the other being oppositely as- I sociated with said input circuits, a receiving circuit differentially associated with said output circuits and a filter in said receiving circuit. I

5. In a multiplex carrier wave transmission system, a receiving s stem comprising a pair of translating devlces having input and output circuits, a circuit for the reception' of signal waves, a second circuit containing a source of energy of frequency substantially equal to that of one of the carrier waves, one of said circuits being symmetrically associated with said input circuits and the other being oppositely associated with said input circuits, a receiving circuit differentially associated with said output circuits and a filter in said receiving circuit. I

6. In a multiplex carrier wave signaling system, a receiving system comprising a duplex translating arrangement having idivided input and divided output circuits, a circuit for the reception of signal waves, a

se'cond circuit containing a source of energy of frequency substantially equal to that of one of the carrier waves, one of said circuits being symmetrically associated with said input circuits and the other of said circuits being oppositely associated with said input circuits, a receiving circuit differentially associated with said output circuits and a filter in said receivingcircuit.

7 A receiving apparatus comprising a pair of translating devices, a circuit upon which carrier currents of different frequencies are impressed, said last named circuit being associated with the translating devices, a source of local oscillations of a period substantially equal to that of one of the carrier currents associated with said repeater circuits, and an dutgoing circuit provided with a low frequency filter associated with source will be effective in the outgoing circuit.

8. In a receiving apparatus, a pair of re- 1 peater, circuits comprising a common conductor and also individual sections, a cir cuit upon which carrier currents of. different frequencies are impressed, said last named circuit being serially associated with the individual conductors of the repeater circuits, a source of local oscillations of a period substantially equal to that of one of the carrier currents associated with the common conductor-of the repeater clrcuits, and an outgolng c1rcu1t provlded w1th a low fre-' quency filter associated with said repeater circuits, whereby only the low frequency signals impressed upon the carrier currents of the frequency of the local source will be effective in the outgoing circuit.

9. In a receiving apparatus, a duplex repeater arrangement comprisin a pair of input and a pair of output circults, each pair having a common conductor, a circuit upon which carrier currents of difierent frequencies are impressed, said last named circuit being serially associated with the two' input circuits, .a' source of local oscillations of a frequency substantially equal to that of one of the carrier currents associated with the common conductor of said input circuits, and an outgoing circuit provided with a low frequency filter, differentially associated with the output circuits, whereby only the lowfrequency signals impressed'upon the carrier currents of the frequency of the local source will be effective in the outgoing circuit.

10. In a receiving apparatus, a pair of repeater circuits comprising a common conductor and also individual sections, means for applying receivedoscillations to said repeater circuits in such manner as to react serially upon the individual sections thereof, a source of local oscillations of a fre quency slightly differing from that (if the received oscillations, means associating the local source with the common conductor of the repeater circuits, and an outgoing ciroscillations and another of said independent circuits comprising a receiving circuit, one

of said independent circuits being associated with said common path.

12. A translating apparatus comprising a duplex translating arrangement including a common path and individual paths, a plurality of independent circuits, one of said independent circuits comprising a source of modulated high frequency oscillations, another of said independent circuits comprising a source of unmodulated high frequency oscillations and another of said independ ent circuits comprising a receiving circuit,

I one of said independent circuits being associated with said common path, and the others of said independent circuits being as sociated with. said individual paths.

13. .A translating apparatus comprising a du lex translating arrangement, parallel circults for said translating arrangement including a common path' and individual" paths, conductive evacuated gaps in said individual paths, a source of unmodulated high frequency oscillations and a source of modulatQd high frequency variations associated with said circuits, one of said sources being associated with said circuits through said common path, and the other of said sources being associated with said circuits through said individual paths. 1 15. A translating apparatus comprising a duplex translating arrangement, parallel circuits for said translating arrangement including a common path and individual paths, conductive evacuated gaps in said individual paths, a plurality of independent circuits comprising a source'of unmodulated high frequency oscillations, a source of modulated high frequency oscillations and a receiving circuit," one of said independent circuits being associated with said parallel circuits through said common path.

16. A translating apparatus comprising a duplex translating arrangement, parallel circuits for said translating arrangement including a common path and individual paths, conductive evacuated gaps in said individual paths, a plurality of independent circuits comprising a source of unmodulated high frequency oscillations, a source of modulated high frequency oscillations and a receiving circuit, one of said independent circuits being associated with said parallel circuits through said common path, and the others of said independent circuits being associated with said parallel circuits through said individual paths.

17. A receiving apparatus for carrier wave signaling systems comprising a duplex translating arrangement including a common path and individual paths, a circuit'for the reception of high frequency signals, a second circuit including a local source of high frequency energy, one of said circuits being associated with said common path and the other of said -circuits being associated with said. individual paths, an outgoing circuit associated with said translating arrangement, and a filter in said outgoing circuit.

18. A receiving apparatus for carrier wave signaling systems comprising a detecting arrangement for translating highfrequency received oscillations into low frequency signaling current, a circuit to supply high frequency r'eceived oscillations to said detecting arrangement, and a circuit for supplying local high freqnencenergy name to this specification,.'in the presence to said detecting arrangement, sai CiICUJI'S of two subscribing witnesses; this 15th day being so associated with said detecting arof March, 1917. rangement that energy from said last men- JOHN R. CARSON. 5 tioned circuit will not react upon said first Witnesses:

mentioned circuit. RALPH W. WOLF,

In testimony whereof I have signed my FREDK S. ROBINSON.