US1438988A - High-frequency translating circuits - Google Patents

Description

Dec. 19, 1922. 1,438,988. L. ESPENSEHIED ET AL.

HIGH FREQUENCY TRANSLATING CIRCUITS.

ORIGINAL FILED SEPT-30,19I9.

dIIi 2 I is meant any Patented Dec. 19, 1922 LLOYD ESPJENSCHIED. 0F QUEENS, AND HERMAN A. AFFEL, 0F BROOKLYN, NEW YORK, v 'ASSIGNOES TO AMERICAN TELEPHONE AND TELEGRAPH COMPANY, A CORPORA- TION OE NEW YORK.

HIGH-FREQUENCY TRANSLATING CIRCUITS.

original application filed September 30, 1919, Serial No. 327,399. Divided and this application filed may To all whom it may concern:

Be it known that we, LLOYD Esrnnsomnn. and HERMAN A. AFFEL, residing at Queens and Brooklyn, in the counties of Queens and Kings and State of New York, respectivel have invented certain Improvements in B igh-Frequency Translatmg C rcuits, of which the following is a speclficatlon.

This invention relates to'high frequency translating circuits, and more particularly to arrangements for modulating currents of various frequencies. v p

This application 1s a d1v1s1on of our ooending application, Serial No. 527,399, filed September 80, 1919, entltled High frequency translating circults.

As is well known, modulation of a plurality of frequencies consists 1n the superposition of the input currents upon each other, either in the modulator element, or at some point in the input side of the said element. By the term modulator element ortion of an electrical circuit, the electrical constants ofwhich may be varied in accordance with slgnal variations; thus, it maybe a vacuum tube 1n which the output resistance 1s varied in accordance with grid potential, or an electric arc, the resistance of which is a funct on of the-impressed voltage, or, it may be a reactance element such as an lnductance, the efiective permeability of which is varied by a controlling circuit, or a condenser, the capacity of which may be controlled by variation in the plate separation or 1n the d1- electric constant. 0

It is desirable, therefore, to provide means for superposing the two input currents so as to avoid loss of energy and diminution of modulating efficiency arising from mutual shunting efi'ects. There are, in general, two ways whereby the input currents may be superposed so as to be rendered mutually non-interfering, one known as the method of balance and the other as the method of frequency selection; It is the object of this invention to show means for superposing the input circuits upon each other by the method of frequency selection,

Serial Ito. 170,584.

a magnetic translating device such as a magnetic modulator.

Thls invention will be better'understood from the following description read in connection with the attached drawing of which F1gure 1 shows a form of invention embodymg the principle of selectivity alone and Flgure 2 shows the combination of selectivity and balance to prevent mutual interference between the respective input circuits of the common modulating device.

Figure 1 shows a way in which the method of frequency selection may be applied to a magnetic translating circuit. T, represents a source of low frequency signallng currents connected with an amplifier A, whereby the amplified currents will pass through the low passfilter F, and be impressed upon the iron core modulating device M, by means of the winding 1. High frequency oscillations from the source G, which, may be of any well-known type of generating device, may be impressed upon the amplifierA and the amplified currents passing through the high pass filter 'F will be impressed upon the modulator M, by means of the winding 2'. The third winding 3 of the modulator is connected with a source of current B, by means of which the proper degree of saturation of the iron core of the modulator M, may be maintained, and a filter F 3 is inserted between.

the source and the winding 3 to prevent shunting the low frequency voice currents and also the high frequency carrier current. A fourth winding 4 is connected with a tuned output circuit coupled with the antenna X. In the operation of this circuit, low frequency signaling currents set up by T, are amplified by the amplifier A, and pass through the low frequency filter F, to

the modulator S-imultaneousl high frequency carrier currents produc by G and amplified by A pass through the high frequency filter F and are likewise 1mpressed upon the modulator M It will be seen that high frequency osclllatlons cannot pass through the low passfilter F the low frequency circuit, and slmilarl low frequency currents cannot pass throug the high pass filter F to the hlgh frequency genera-ting circuit. In this manner interference between the input circuits is avoided, and the modulated oscillations are transmitted by the winding 4 to the antenna circuit X. p L

Figure 2 shows an arrangement in which the principles of selectivity and of balance are combined for preventing interference between the input circuits of a magnetic modulatiiig device. The low frequency c1rcu1t has therein a transmitter T and a low pass '1 filter F The low frequency signals set u 1 high in this circuit are impressed across the win ing 1 upon the central arm of the core of the modulator M High frequency oscillations from the generator G pass through the ass filter-F andare impressed upon the winding 2 upon one of the side arms of the core ofthe modulator M symmetrically arranged upon the same core is a winding 3 which. is connected with the output ClICIllt: L Low frequency currents impressed upon winding 1 set up therein, a flux which divides in the arm of the core upon which the winding 2 is placed, half of the flux passing up- Ward and half downward, which creates a neutral condition preventing induction of currents in the winding 2 upon this core. In a similar mannervthe flux set up by. the high frequency winding 2 will not induce high frequency oscillations in the low frequency circuit. Filters F and F interposed in the low frequency and high frequency input circuits respectively prevent the passage of high frequency and low frequency currents through filters F and F respectively. If lowfrequency signaling currents are impressed upon the winding '1 upon the central arm of the core, the resulting fluz: will change the permeability of the core with respect to the winding 2. The high frequency current set up in, the winding 2 by means of the source G will be modulated accordingly, and the modulated high frequency current will be impressed-upon the winding 3 of the output circuit L This arrangement shows means for combining frequency selective devices with a balanced iron core modulator, thereby assuring a higher degree of freedom from interference of the oscillations in one of the input circuits bythose in the other input circuit.

The circuit arrangements shown in the drawing are not limited to a particular type of output circuit, such as aradio antenna or a metallic transmission line, but either arrangeme'nt is equally well adapted to be used with either type of output circuit. Although this invention has been shown as embodied in a particular form, it is to be understood that it is not so limited, but is capable of embodiment inother forms Without departin from the spirit and scope of the appended claims. 4

v What is claimed is:

1. In a hi h frequencysignaling system, the combination of a balanced iron core modulating device, input circuits adapted to impress carrier current andsignaling current upon said translating circuit and frequency selecting means associated with each input circuit to exclude from each respective circuit currents having frequencies different from that of said circuit.

2. In a high frequency signaling system, the combination of a magnetic translating device of a plurality of input circuits, each having a source of current of a definite frequency, and also a selective network adapted to transmit that frequency of the particular source with which the said network is associated.

3. Ina high frequency signaling system,-

connected with a third winding and having selecting means connected between said winding and said source, and anoutput circuit connected with a fourth winding 4. In a high frequency signaling system. the combination of an antenna of a magnetic modulator having a plurality of input circuits, each characterized by a source of current of definite frequency, and a filter adapted to transmit readily current of that particular frequency. 4

5. In a high frequency signaling the combination of an antenna 0 a magnetic translating device comprising a plural-- ity of input circuits, each characterized by a system,

source of current of a definite frequency, and

a filter adapted to transmit the said fre-.

quency.

6'. In a high frequency signaling system, the combination of a transm tting, circuit of a magnetic modulator having input circuits so arranged as to prevent undesired induction of current from one input circuit into another input circuit, .each of the said input circuits being characterized by a source of naeaeee current of a definite frequenc and by a filter adapted to transmit the irrequency of its respective circuit.

7. In a high frequency signaling system, the combination of a magnetic modulator having a plurality of windings, an output circuit, a plurality of input circuits, each characterized by a source of current of definite frequency, and a filter to transmit the said frequency, the said circuits being rendered mutually non-interfering by means of their connections With the windings of the said magnetic modulator.

In testimony whereof, I have signed my name to this specification this 13th day of 15 May, 1921.

LLOYD ESPENSCHIED.

. In-testimony whereof, I have signed m

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