US1333376A - Oscillation-generator for wireless systems - Google Patents

Description

M. BEREL A D L. FUNKE.

OSCILLATION GENER ATOR FOR WIRELESS SYSTEMS. APPLICATION man JUNE 20. 1918.

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A TTOR/VEYS M. BEREL AND L. FUNKE. OSCILLATION GENERATOR FOR WIRELESS SYSTEMS.

APPLICATION F ILED JUNE ZO, 1918. 1,333,376.

Patented Mar. 9,1920.

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1 ,333,376. Patented Mar. 9, 1920.

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APPLICATION FJLED JUNE 20.1918.

1,333,376.- Patented Mai. 9,1920.-

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MILTON BEREL,-OF NEW YORK, N. Y., Am) LOUIS FUNKE, or NEWARK, NEW JERSEY.

OSCILLAT ION-GENERATOR FOR-WIRELESS SYSTEMS.

Specification of Letters Patent.

Patented Mans), 1920.

Application filed June 20, 1918. Serial No. 241,008.

New Jersey, have invented a new and Improved Oscillation-Generator for Wireless Systems, of which the following is a full, clear, and exact description.

This invention relates to a system of radiotelegraphy and radiotelephony for sending and it has for its general object to provide a high frequency polarity reversing switch in novel combination with a source of electro-motive force, direct or alternating, and a condenser, whereby the terminals of the condenser are reversed with respect to the terminals of the source of electromotive force in rapid succession to produce continuous oscillations of radio frequency for radio purposes.

The advantages of the foregoing novel combination are asfollowsz. 4

a. With direct current the condenser, after being charged to a definitepolarity, acts as an open circuit to an E. M. F. of like polarity (c. 9., the charging source of power), but the application of an opposite E. M. F. (e. 9., reversing the polarity of the source of power), will cause to flow sufficient energy to neutralize the original charge and to recharge the condenser to this second polarity.

b. With alternating current the individual cycles are broken up into a large number of smaller component charges per second, functioning to charge the condenser as with the direct current source, consecutive charges being reversed; consequently a flow of current takes place, due to neutralization and recharging on account of reversalssimilarly as with the direct current, but this flow of current is entirely independent of the current conducting property of the con- (lenser with reference to the original cyclage of the source of power, the flow of current being entirely byvirtue' of the action of the high frequency reversing switch.

a. In using a direct current source of energy a pure undamped wave with no compensation wave is obtained.

In using an alternating current source of energy a continuous wave with periodic variations corresponding to the source of power (superimposed frequency) is obtained, to which ordinary receiving apparatus will respond.

d. There is no limit to the amount of power that may be handled on account of the comparatively small quantity of energy handled per contact.

e. The transmitting condensers used in this system differ radically in magnitude and construction from those used in conventional radio systems. Whereas in our system the capacity may be of the order 1 mi crofarad upward, in other systems 0.006 M. F. is considered a large capacity. Our large capacity condensers are of smaller physical dimensions (externally) than these other condensers of smaller capacity because ours are constructed for low voltage charges, rendering the use of bulky dielectric ma terial unnecessary; but either method of construction may be adopted.

f. Reception: In unidirectional single wheel break receiving systems, alternate semi-periods of the incoming oscillations are inactive, thereby-eliminating one-half of the incoming energy. By virtue of the high frequency reversing switch these lost semi-periods are rectified and rendered available for the telephone circuit, thereby giving double efiiciency. Consequently our receiver will more readily respond to a dis-' tant transmitter, and for communicating'a certain distance would require smaller power expenditure at the transmitter.

g. Oscillations of either great or small amplitude may be generated by the high frequency reversing switch, and in the latter case the oscillations may be used to heterodyne incoming oscillations, producing an audio beat frequency which actuates a crystal or other rectifying receiver in the ordinary way.

For a more detailed understanding of the invention reference is to be had to the following description and claims taken in connection with the accompanying drawings, which illustrate certain embodiments of the invention and wherein similar characters of reference indicate corresponding parts in all the views.

Figures 1, 2 and 3 are different forms of transmitting circuits;

Fig. 4 is a diagrammatic view of a receiving circuit;

Figs. i l and i are simplified circuits, showing different operative conditions of the circuit in Fig. 4;

Figs. 5 and 6 are diagrams of other arrangements of receiving circuits;

Fig. 7 is a side view of the high frequency reversing switch;

Fig. 8 is a curve representing the incoming undamped oscillations on a receiving antenna;

Fig. 9 is a curve showing the rectifying effect of the high frequency switch on the incoming oscillations when the number of contacts of the high frequency reversing switch slightly exceeds the number of incoming alternations per second.

Fig. 9 shows the effect of the conventional make-and-break systems on the incoming oscillations when the number of contacts of the make-and-brake system slightly exceeds the number of incoming cycles per second.

Fig. 10 is Fig. 8 repeated for comparison with Fig. 11;

Fig. 11 represents the rectifying effect of reducing the number of contacts of the high frequency reversing switch to one-third of the number of the incoming alternations;

Fig. 12 shows curves representing (a) incoming oscillations, (2)) local oscillations, (c) resultant oscillations, (at) rectification of resultant oscillations, (e) telephone cur rent;

Fig. 13 is a curve representing the oscillations in the condenser circuit due to the action of the high frequency reversing switch on a direct current, or it may represent the exciting and antenna currents when the wave length of the antenna corresponds to the cyclage of the break;

Fig. la is a curve representing the oscillations in the condenser circuit due to the action of the high frequency reversing switch on an alternating current, or it may represent the exciting and antenna currents when the wave length of the antenna corresponds to the cyclage of the break.

Fig. 15 is a curve showing unidirectional impulses in the exciting inductance when the latter is directly in the power circuit of the high frequency reversing switch and direct current is used;

Fig. 15 is a curve showing the corresponding antenna current when the cyclage correspondin to the antenna wave length is equal to the number of impulses above described;

Fig. 16 is a curve showing exciting impulses in the exciting inductance when alternating current is used and the exciting inductance is directly in the power circuit of the high frequency reversing switch, and

Fig. 16 is a curve showing the corresponding antenna current under the same conditions as mentioned above for Fig. 15.

'pacity O. farads, a quantity of electricity flows into the condenser and charges it, according to equation:

Q, (coulombs) OE.

By suddenly andabruptly reversing the polarity of the source of current with respect to the condenser, a quantity Q of electricity, but of opposite polarity, will flow into the condenser and neutralize the original charge; and on continued contact the condenser will receive a further quantity Q, becoming charged to the second polarity. The total quantity flowing is then equal to 2Q. 1

2. The quantity Q, is of small order. Therefore, to give an appreciable amount of energy it is necessary to repeat the reversing operation many times per second. When the frequency of contact is brought to 10,000 or over, the frequency of the current is radio frequency, and etheric disturbances can be set up. The reversing operation is accom plished by means of the following described high frequency reversing switch.

To better comprehend the diagrams the high frequency reversing switch X will be explained in connection with Fig. 7 This switch comprises a rotating element 1 mounted on a shaft 2 which is driven at a suitably high speed by any convenient means. The shaft 2 is mounted in a frame that includes uprights 3, only one of which can be seen in Fig. 7 the uprights being carried by a base at on which and at opposite sides are brush holders 5 which are vertically adjustable in posts 0. In the holders are brushes 7 and 8 which bear on the pe riphery of the rotating element 1 at spaced points, each brush having a stem 9 passing through the holder 5, and on the stem is a spring 10 which urges the brush toward and in contact with the periphery of the rotating element 1. The rotating element 1 in the present instance is composed of a body of insulation 11 into opposite sides of which are set metallic rings 12 with gear-like teeth 13 on one ring and gear-like teeth l-t on the other ring, the teeth being staggered and forming contacts with which the brushes 7 and 8, engage. The teeth of one ring are directly opposite the insulating space between the teeth of the adjacent ring, and the insulating spaces circumferentially considered are wider than the contact points 1? or 14. so that open circuit intervals will be provided between the times of successive engagement of the brushes with teeth. The

brushes 7 and 8 are as wide as the peripheral face of the wheel 1, so that they w ll have electrical engagement with both sets of con tacts 13 and 14, and the brushes are so re-- lated to each other that when the brush 8 is engaged with the front ring (for instance, by bearing on a tooth 13), the brush 7 will be out of electrical engagement with the frontring but in electrical engagement with the rear ring by contacting with one of the .teeth 14. As the wheel rotates, this" condition is immediately reversed and the brush I 7 engages a tooth 13 and the brush 8 engages a tooth 14, these reversals taking place in the present system at the rate of 10,000 and upward per'second. The front and rear rings also function as slip rings and have bearing constantly against them brushes 15 and 16, whereby they cooperate with the brushes 7 and 8 to make and,break the circuit. Obviously other constructions may be employed to obtain the two series of contacts with cooperating brushes for producing polarity reversals at high frequency, but the arrangement shown is illustrative of one simple arrangement. In Fig. 1 the rotating element of the reversing switch is shown developed for enabling the complete circuit to be easily traced, but in the remaining diagrams the reversing switch is shown with the rotating element in edge view.

Referring to the various transmitting 01a cuits shown in Figs. 1 to 3 inclusive, A designates the antenna; G the ground (earth) connection; L a tuning inductance; L a tuning inductance or helix; L L the primary and secondary, respectively, of an oscillation transformer; C the transmitting condenser; M the microphone for radiotelephony with short-circuiting switch S; X the transmitting high frequency revers .ing switch with brush terminals 7, 8, and

wheel terminals 15, 16; K a transmitting key with short-circuiting switch S Choke coils c are inserted in the main lines on to prevent radio frequent! current from entering the alternating current ordirect current generator 7.

In the circuit diagrams, Figs. 1 and 2,the

current in the exciting circuits, while, due to the same number of contacts, reverses with each succeeding contact giving r se to an alternating current effect of the, same number of alternations as there are contacts. Thus at 30,000 contacts per second the corresponding alternating current cyc lage is (since there are two alternations per cycle). The corresponding 1 (wave length) is therefore 20.000 meters.

leferring to Fig. 1, if the number of contacts of the high frequency reversing switch is equal to 2.N, then the corresponding oscillatory cyclage is N. It is clear that if the antenna is tuned to resonance with this frequency, maximum efiiciency and radiation will result. To radiate shorter wave lengths while'maintaining the same high frequency reversing switch speed, the antenna wave length is adjusted .sothat the antenna oscillates several cycles between successive contacts of the switch, during which period the condenser is discharging into the antenna, and the contacts occur'so that the antenna oscillations are in phase with the condenser action. See Figs. 13 and 1% In this circuit the method of introducing energy into the antenna is by the use of a direct capacitative coupling.

In radiotelegraphy M is short-circuited by switch S, K is operative by keeping switch S open, X is operative, and either an alternating current or a direct current source of energyis used.

In radiotelephony M is operative by keeping switch S open,\K is short-circuited by switch S X is operative, and a direct current source of energy is used. I

be accomplished as described in connection with Fig. 1.

Referring to Fig. 3, in this circuit the the high frequency reversing switch. By

radiated frequency is 2.N for 2N contacts of virtue of the method of connection, unidirectional impulses flow throughthe exciting inductance. If this inductance is either inductively or conductively coupled (as shown) to an antenna circuit the corresponding frequency of whose period is equal to the number of impulses, then the antenna will oscillate at that frequency and inphase with the switch and exciting circuit, performing the reverse half cycle durj ing the no-contact period of the switch. See Figs. 15, 15 16 and 16. i

. The exciting inductance in this case is inserted in the power side of the high froquency reversing switch and therefore the current in it is always of the same polarity, the action of the sw tch being to render the current discontinuous at the rate of contact of the switch X n' The lilltlallZfltlOn and recharge going on inthe condenser 0 gives rise to this withdrawal of energy from the mains.

- Radiotelegraphy and radiotelephony may be accomplished as described in connection withfFig. 1.

In referring to the receiving diagrams, A designates the antenna; G the ground (earth) connection; L a'loading inductance; L a tuning coil (inductance); L L the primary and secondary respectively, of a receiving transformer; I 1 L the secondary and primary, respectively, of an oscillation transformer for exciting the antenna circuit with local oscillations; S a double pole double throw switch with contacts 29, 30 and 31, 82; V a variable series condenser; X the receiving high frequency reversing switch with brush contacts 19, 20 and wheel contacts 21, 22; V a variable capacity connected to wheel contacts 21, 22; S a polechanging switch with contacts 23, 24, and 25, 26, S a short-circuiting switch for X V a variable stopping condenser; V a variable secondary condenser; R telephone receivers; D a detector; B a battery; P a

potentiometer; S a two point switch with contacts 27, 28; I an interrupter.

In receiving, our system depends upon the following:

The same high frequency reversing switch may be used for reception by (w) the heterodyne method, and (6) without the aid of local oscillations and detector.

((4) Heterodyne method.

(6) Method without the use of local oscillations and detector.

1. At a 10,000 meterincoming wave length, N:30,000 and the number of alternations: 60,000. At 60,000 contacts per second our switch produces complete rectification,

bringing up the negative halves of the incoming oscillations on the positive side, or vice versa. Operation of the swltch above or below this synchronous speed gives rise to an audio frequency proportional to the variation (see Figs. e, S and 9). Therefore, the maximum energy is effective when there is one contact of the switch per incoming alternation.

2. Any variation may be instituted in the number of contacts made per second, whereby the contacts will occur as compared to the incoming oscillations so that the actire portions of cycles as produced by the switch will be rendered either all on the positive or all on the negative side of the zero line; then by proper variation either above or below this speed, audio frequencies,

In Fig. 4 the circuit is a composite one containing three methods of reception of radio signals. In this circuit a local unidirectional discontinuous current is obtained corresponding to the effect of passing an alternating current of the frequency of the number of contacts through a rectifying detector. If the battery and detector polarities are properly adjusted, the incoming oscillations are rectified by the detector and combined with the local unidirectional impulses, giving the beat frequency in the telephone receivers. Here the local oscillations, when necessary, are applied to the secondary conductively; when local oscillations are not necessary in functioning reception, they are eliminated by closing switch S and having X inoperative.

Method 1.'Heterodyne (production of local oscillations.) See Fig. 12.

Method 2.'The reduction of incoming undamped oscillations to audio frequency Without the aid of local oscillations.

A. If X is operated so that a contact is made per incoming alternation, maximum energy is given to the telephone receivers because the switch X makes each and every half cycle eflective by virtue of its rectification action. Suitable audible response in the telephone receivers is obtained by varying the speed of X properly above or below that required to give one contact per alternation. See Figs. 8 and 9.

B. Reception may also be effected if X is rotated so as to render any number of not necessarily consecutive portions of cycles of opposite polarities on the same side of the zero line. Audible response in the telephone receivers is obtained by proper varia 'tion above or below the speed required for this action. frequency:30,000, the number of contacts For example, if the incoming should be 20,000-plus or minusfor next to the maximum audible response. This is applicable for short distance work with high powered stations by simply reducing the speed of X See Figs. 10 and 11.

M ethotl 3.Conventional crystal receiver for damped oscillations:

To obtain Method 1 from Fig. 4:

Throw switch S. to contacts 20, 30.

Throw switch S to contacts 26,

Throw switch S 4 open,

Throw switch S to contact 2%.

Adjust speed of X Adjust capacity V Adjust battery and potentiometer circuit, including detector D. (See equivalent Fig. 4 V

To obtain Method 2 from Fig. 4:

Throw switch S to contacts 31, 32, v 7

Throw switch S to contacts 23, 24 (short circuit),

Throw switch S, open,

Throw switch S to contact 27 Adjust speed of X Ad ust capacity of V to zero,

Adjust capacity V See equivalent Fig. 4

o obtain Method 3 from Fig. 1: Throw switch, S to contacts 29, 30,

- Throw switch S to contacts '25, 26,

Throw switch S closed,

Throw switch S to contact 28,

K becomes inoperative, Y

' Adjust capacity V I (See equivalent Fig. 4).

The circuit in Fig. 5 is an alternative to the circuit in Fig. 4*. It consists of a conventional receiver to which is coupled the source of local oscillations consistin of the I high frequency reversing switch condenser V in shunt with X terminals 21, 22, the brushes 19, 20 of X3 being connected to battery regulated by a potentiometer and in series with the exciting inductance L,. Then, as described in transmitting circuit, Fig. 3, radio frequency impulses are made to flow through L inducing current of'similar frequency 1n the antenna circuit'through L to which it is coupled. If the proper frequency difference exists between the incoming and local oscillations a resultant beat frequency becomes effective in the secondary circuit (L,,, V,) which, after rectification by the detector D, becomes audible in.

the receivers R (see Fig. 12.) Transmitting methods No. 1, 2 or 3 may be used for the introduction of the local oscillations.

In Fig. 6, if incoming wave length equals 10,000 meters, there will be 60,000 incoming alternations per second. By induction these oscillations are reproduced in circuit L V and if high frequency reversing switch X is revolved in synchronism (at 60,000 contacts per second), complete rectification of the incoming oscillations is produced, which in turn, w1ll charge the condenser. V

Around the condenser V is shunted some kind of mechanical break or interrupter I inseries with the receivers R. The charge on the condenser V will produce a tone in the receivers R, of frequency dependent upon the rate of contact of the interrupter. (With -each contact of the mechanical interrupter the charge on condenser V will be discharged through receivers R and cause the receiver diaphragm to respond in the form of a click.

- In all circuits transmitting and receiving,

. the transfer of energy from one circuit to source and unmodulated antenna current,

radiation is undamped and the production of an audible-tone is left to the receiver (see Figs. 4., 4:, 5 and 6. y

If antenna current is modulated with a microphone or an alternating currentsource of energy is used, the audio frequency is carried by the radiated waves rendering tone production at the receiver unnecessary. Hence, an ordinary crystal receiver will suffice (see Fig. 4 or 5, but with exciting circuit inoperative).

In Fig. 8 the curve is supposed to represent 15 incoming oscillations in a period of 1/2000 ofa second. If the high frequency reversing switch-is operated to make 60,000 contacts per second, or 15 in 1/2000of 'a second, every other alternation will be switched in polarity to the opposite side of thebase line; that-is to say, the portions a a a a etc., will be shifted to the positive' side of theline wm, as indicated by the dotted lines.

Fig. 9 shows sixteen local superimposed cyclicimpulses due to the high frequency reversing switch impressed on the circuit in 1/2000 of a second, and the resultant effect on the incoming oscillations will be an audio frequency current indicated as the gradual decay and building up process in this figure.

F 9 in relation to Fig. 9 serves to illustrate that with the conventional single wheel make and break system only one-half of the available energy is made use of. y

Fig; 11 incomparison with Fig. 10 shows the effect of materially varying the number of contacts or reversals due to the high frequency reversing switch. In Fig. 10 the curve w w represents incoming oscillations of 30,000 frequency, and Fig. 11 represents the effect of the switch making 20,000 contacts per second, whereby every other one and one-half alternations are lost and every other of the remaining one and onehalf alternations are reversed, as indicated at 1' 1 1' To produce audio frequency, but at reduced energy the high frequency contacts slightly different from that speci fied above.

Fig. 12 illustrates a group of curves showing the functioning of the heterodyne receiver, the curve a representing the incoming oscillations, b the local oscillations, c the beat current, 03 the rectified beat current, and e the periodic telephone current which is brought about by the use of the high frequency rectifier (detector) in the receiving circuit. I

The curve shown in Fig. 13 represents the exciting and antenna current when the wave length corresponds to the cyclage of break reversing switch is operated at a number of when the high frequency reversing switch is used in connection with direct current. In Fig. 14: the effect of the high frequency reversing switch on an alternating current is depicted. In both figures the reversals are designated by 1. The exciting circuit here is the condenser circuit.

When the high frequency reversing switch is used with direct current and makes 30,000 contacts per second, the action in the sending circuit is'shown in Fig. 15, which represents the unidirectional impulses in the exciting inductance when the latter is inserted in the power circuit. Fig. l5 rep resents the antenna current resulting from such impulses, the negative portions of the curve in Fig. 15 being of slightly less am-- While the foregoing describes our invention as related to both transmitting and receiving wireless systems, the following claims only appertain to thataspectof our invention wherein it embodies an oscillation generator.

Having thus described our invention, we claim as new and desire to secure by Letters Patent:

1. In an oscillation generator, the combination of a source of electromotive force, a choke coil connected with each terminal of the said source, a high frequency reversing switch operating at a speed to produce substantially at least 10,000 reversals per second, a key and short-circuiting switch between one of said choke coils and one of a pair of commutating brushes of the high frequency reversing switch, an energy transference device between the other said choke coil and the other of the same pair of coinmutating brushes of the said high frequency reversing switch, and a condenser electrically connected to the other pair of brushes making continuous electrical connection with the high frequency reversing switch.

2. In a device of the character described, the combination of a power source and a circuit comprising a choke coil, a switch and an energy transference. device in series with said source of power, a commutating device having two independent pairs of brushes, one of. the pair of brushes of the said commutating device being connected in series with said circuit, and a condenser, said cons denser being connected to .the other pa1r of terminals of the commutatlng devlce.

3. In a device of the character described,-

the combination of a power source and a circuit therefor including a choke coil, a key, an energy transference device and a commutating device, said commutating device having two pair of brushes, one of said pair forming a series circuit withthe source of power, and a condenser, the other pair of brushes being connected with said condenser and forming an independent circuit therewith.

MILTON BEREL.

LOUIS FUNKE.

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