US1569481A - High-frequency-generating system - Google Patents

Description

Jan. 12,1926. 1,569,481

W. E. E. HABANN nmu FREQUENCY GENERATING SYSTEM Filed Nov. 17, 1921 2 Sheets- Sheet 1 Illlllllllllllll IllHlll ll l 'l 4/ I Inrenfdr.

Jan. 12 1926'. 1,569,481

w. E. E. HABANN HIGH FREQUENCY GENERATING SYSTEM Filed Nov. 17, 1921 2 Sheets-Sheet 2 277/6/7/0/ WZZfWbJ/W? Patented Jan. 12, 1926.

UNITED STATES PATENT OFFICE.

WILHELM EDUA RD ERICK HABANN, OF BERLIN, GERMANY ASSIGNOB TO THE FIRM OF DEUTSGHE TELEPHONWERKE GESELLSCHAFT MIT BESCHRANKTER HAFTUNG,

or BERLIN, GERMANY.

HIGHFREQUENCYGENERATING SYSTEM.

Application filed November 17, 1921. Serial No. 515,896.

7 '0 all whom it may concern:

Be it known that I, \VILHELM EDUARD ERICK HABANN, citizen of Germany, residing at Berlin, Germany, have invented a certain new and useful High-Frequency-Generating System (for which I have filed an appllcation in Germany partly on Nove'mber'18,

1920, and artly on April 15, 1921, in Denmark on ctober 10, 1921, and in France on October 10, 1921), of which the following is a specification. v

This invention relates to improved means for production of high-frequency oscillations affording a highly valuable alternative to production by the aid of cathode tubes or high-frequency machines, from the point of view of capability of regulation and adjustment as Well as from the point of view of reliability under continuous operation.

According to the invention, an acoustic glevice (whistle, reed, pipe, siren or the like) is caused to vibrate by means of a continuous stream of air in such manner that air waves of a frequency over 4000 (exceeding the frequency of speech) are produced, and thereupon these air waves are caused to act on a periodic or an aperiodic body capable of being vibrated or oscillated (e. g, a diaphragm microphone, flame microphone, reed or the like) which is so dimensioned that it can follow the frequency of the air waves and itself produces electric changes adapted 'for excitation of an oscillatory circuit. For this purpose the G'alton whistle has. given good results as-an acoustic device.

Now as the result of experimental research I have proved the possibility of producing high-frequency oscillations, in such wise as to meet all requirements in the art. If, for instance, a Galton whistle be used, and if the waves of air produced are caused to act on a microphone, from the whistle air waves are emitted of a frequency of over 4000, which can easily be followed by the diaphragm of the microphone if the adjustment of the whistle and the pressure of the blast be suitably chosen. The whistle may be so blown that fundamental waves of the requisite frequency areproduced, or that besides fundamental waves of low frequency there are produced harmonics of high frequency which are made use of in the sense of the present invention. In the latter case it is preferable to separate the high tones from the lower by resonators, reflectors or the like acoustic means. I

The expression microphone is here used in its broadest sense, that is to say as denoting a periodically or an aperiodically oscil lating body, adapted to produce electric changes, for instance/interruptions. Instead of a diaphragm'inthe usual sense, there may be used a reed, for instance the reed of a reed-pipe, which reed either lies directly within the pipe oris set into oscillation from a separate pipe, say from a reed-pipe.

' When this microphone is shunted into the circuit the current will be divided into impulses ofthe number of the acoustic oscillations. These impulses, according to the invention, are made use of to excite an oscillatory circuit coupled with the first named circuit in such a manner that the oscillatory circuit, according to its tuning, either oscillates to correspond with the impulse frequency, or with a multiple thereof. The first named current can be either taken from a continuous current source, in which case the oscillation circuit continuously produces undamped oscillations which are adapted for telegraphic purposes, or the microphone can be shunted in a speaking circuit of low frequency, when it breaks up the speaking current into impulses which so excite the oscillation circuit as to make it oscillate. In this case undamped oscillations are created, the initial amplitude Values of which correspond to those of the speaking currents of low frequency. The outline curves of the sounding amplitudes will be heard in known manner in the telephone of the receiving station, as words. This method has the advantage over the known combining methods (beat tone) that neither at the distant line nor in the sender, do, high frequency oscillations occur, so long as no speaking currents flow in the low frequency speaking circuit, while the interrupter contact is constantly working. Therefore at times of rest of speech disturbing inductive actions are fully excluded, which inductive actions are otherwise, at such times, caused by the unmodulated high frequency currents. The. invention therefore enables really perfect multiple conversation in the distant line. Instead of a complete interruption at the plate of contact be- 1 tact pieces is changed by glowing gases which are caused to vibrate by the air waves' In lieu of the Galton whistle or reed pipe the known sirens for example, may be used. For multiplex conversation in a conductor having a plurality of frequencies there is-the possibility of providing a series of concentric rows of perforations in the siren disks and of providing a microphone for each row. Such miorophones'are arranged on a radius of the disk, side by side, so that other radii are available for further multiplex conversations.

There is illustrated by way of example in the accompanying drawing an apparatus which has proved to be particularly reliable.

:Fig. 1 is a front view of an acoustic 'generator, and

Fig. 2 a plan of the same.

Fig. 1 is an elevation, and Fig. 1 is a plan, of a siren adapted to.,be used instead of the Galton whistle shown in Figs. 1 and 2.

Fig. 3 is a cross section of a microphone, and

F ig. 4 shows a system of connections suitable for telephony. v

The microphone is differentiated from the microphones used heretofore in respect that it reacts only to high-frequency, but does not startto act appreciably with low frequency (that is to say with frequency less than 4000 to 5000. The diaphragm 1: of this microphone has a thickness of 5/100 to 1/100 mm. and a diameter of 4 to 20 mm. The contact pin 20f the microphone has a pointed or rounded end and is rigidly mounted, as the result of which the operation is limited to constant amplitudes of the air wave's im pinging on the microphone. It has been proved experimentally that so long asno air waves impinge on the microphone the diaphragm 1 will rest hard against the contact pin, since by measurement it has been foundthat the reading is 0 ohms. 'If, however, waves impinge on the diaphragm, the latter. will be lifted off the pin, most probably to effect complete interruption. In this case the resistance of the microphone will fluctuate between 0 and infinity, and the ohmmeter has shown in thecourse of experiments intermediate values, varying from 80 to 300 ohms.

A microphone so constructed will supply high-frequency oscillations perfectly free from objection, if it is excited and connected according to the present invention; and if used for telephony, the speech will be perfectly clean' 1 In the latter case, in which the microphone serves for splitting up speech currents into impulses, the result, as far as clearness in speaking is concerned, can be still further improved by combining the speech current with an additional continuous current.

This additional continuous current will be dividedinto impulses by the microphone and, therefore, will continuously excite the oscillating circuit. Therefore, it is dimensioned in such a manner, that the undamped high frequency oscillations produced thereby in the oscillation circuit, have amplitude values which are considerably smaller than the high frequency amplitudes produced by speech in the oscillating circuit.

In order to prevent the contact between the diaphragm and the contact pin from falling due to oxidation or similar reasons, a drop of oil of viscous quality may be applied between the point or rounded end of the contact pin and the diaphragm.

It is not possible to account for the described peculiar efl'ect produced by the combination with the continuous current. The effect, however, is undoubtedly present, and

is distinctly perceptible as proved by ex-' periment. 1

For adjustment purposes it is desirable that the diaphragm 1 and the contact pin should be movable relatively to one another.- In the present instance the diaphragmis movable, the contact pin being fixedly mounted. For this purpose the diaphragm carrier, which consists on the front side of conducting parts 3, in the middle of an insulation body 4 and on the back of a conducting or metallic part 5, is formed with a perforation provided with an internal thread and screwed on the threaded part of the contact pin 2 by aid of a worm 6 engaging a worm wheel 7 mounted on the. part 4 of the diaphragm carrier. The carrier can thus be r0- tated relatively to the contact pin 2, thus moving the diaphragm 1 towards or away from the pin 2'. The electric current is fed to the diaphragm by means of a sliding contact 8.

The contact pin 2 is fixedly attached to the carrier .9 which conducts the current from the contact pin. The carrier 9 is connected with a plug. 10, and the sliding contact 8 with a inseam ing the width ofthe annular gap between the nozzle 16 and the tube 17. Both the nozzle 16 and the tube 17 are screwed into a yoke 18. The rotatable drum 19 serves for adjusting the effective length of the tube 17- As will be understood from consideration of Fig. 2, the casing 12 of the microphone is arranged parallel to the whistle in such manner that the trumpet'13 will lie just opposite the mouth of the whistle, and the distance of the dia hragm from the centralline of the whistle is adjustable at right angles to the latter. For this purpose the plugs 10 and 11 are set into metal plates 21, 22 which are separated from one another by an insulating bod 20, the metal plates being adapted to be siifted on the base plate 23 of the generator by manipulation of the knob 24. The terminals are constituted by binding posts 26.

Opposite the trumpet 13 of the microhone on the other side of the whistle mouth IS a reflector 27, which may be flat or curved in conformity with the shape of rounded waves; for instance it may be parabolic. This reflector is adapted to oscillate about a stud 28, on which a carrier arm 30 is pivoted in such manner that it may move in a plane parallel to the axis of the whistle. In horizontal position the carrier arm 30 of the reflector 27 will rest on an abutment 29. The reflector is itself shiftable at right angles to the axis of the whistle, being connected with the arm 30 by a threaded spindle 31.

The adjustment is effected in the following manner:

First the length of the tube 17 is set, and then the microphone is caused to approach the whistle, the reflector being turned to one side until the optimum tone strength is obtained. Thereupon the reflector 27 is turned into the position shown in Fig. 2, and is moved towards the whistle until the greatest clearness, that is to say if a telephone is used, the greatest speech clearness is obtained. The pressure of the air stream fed by the pipe 14 or at the mouth of the whistle may be finally regulated. The reflector serves as an acoustlc intermediate circuit.

The effect is based on the fact, that the reflector selects out of the air waves, which are generated by the whistle between the reflector and the microphone diaphragm, those having a length which is proportionate to the distance for the microphone diaphragm In this way a certain wave will act on the diaphragm to a maximum, while the energy of'the' rest is weakened by the counter balancing of the direct and the reflected waves.

The whistle can now be blown in such manner that-the air wavesproduced have a frequency of over .000, or it may be blown to produce lower notes or tones, the higher harmonics of which, exceeding the frequency of 4000, are caused to act on the diaphragm 1 of the microphone.

In the apparatus shown in Figs. 1 and 1 a microphone 12 is used, of the construction shown in Fig. 3, provided with a regulating screw 6 and with the prolongation tube 32 of the trumpet 13. This tube 32 has its hearing in a bracket 33'arranged laterally of the rotating perforated disk 34 in such way that a stream of air blown by the nozzle 35 through the outer circular row 34' of perforations passes by way of the tube 32 to the microphone 12. The disk 34 is journaled on pivots in the bracket 36, and is rotated by the cord 37 at a comparatively high speed which can be regulated. When the disk 34 is rotating the stream of air coming from the nozzle 35 is interrupted or divided up into separate impulses by the perforated disk, thus creating corresponding oscillations of the diaphragm of the microphone. The device thus operates according to the principle of sirens. There is a second or inner row 34 of perforations, against which a second nozzle 38 blows a stream of air adapted to act on a second similar microphone of which, for the sake of clearness, only the tube 39 forming a prolongation for its trumpet is shown. The siren is thus adapted to be used for two speeches on the same conductor simultaneously, the high frequency oscillations carrying the one or the other speech have different frequencies.

In Fig. 4 is shown a system in which the acoustic generator is used for telephone purposes. 10 and 11 indicate the plugs for the microphone. These plugs are placed in a circuit to which the speaking currents from the low frequency subscribers station are conducted by the transformer T on both sides of the condenser K. The battery Z produces the additional continuous current mentioned above. They speaking currents are divided by the microphone into impulses and are then conducted to the oscillatory circuit S which, in turn, is coupled for instance with a long-distance line F. It is of importance that the oscillatory circuit S be coupled in the correct manner, for which there is an optimum. The coupling for 1 this purpose is such that it is variable at The speaking currents of low .frequency, which are divided into impulses by the interrupter can be increased before they are" led into the circuit. An intensifier of any known construction serving this purpose is shown at M in Fig. 4. By giving a reinforcing tube (cathode tube) the necessary'dimansions, it is possible to protect the microphonic interruption contact against current overloading due to too loud speaking.

The frequency produced by the oscillation circuit can be increased. to any desired amount by magnetic frequency converters, as indicated at N in Fig. 4, before entering the main conductor or the distant conductor, or the antennae.

When working with continuous current the acoustic generator will give perfect undamped oscillations and with speaking currents damped oscillations suitable for telephone purposes. The microphone, however. can also be used as a means for rendering audible undamped oscillations which in the detector circuit are not audible by themselves. For this purpose he microphone will furnish anadditional wave owing to the excitation with continuous current, which additional wave will interfere with the foreign wave audibly. The production of continuous currents may also be dispensed with, in which case instead of the continuous current the foreign wave is sent into the microphone, and there operates audibly.

I claim:

1. High frequency generating system consisting of an acoustic device, which produces air-waves of a frequency over 4000 p. sec., a vibratory device acted upon by the said airwaves and being capable to vibrate in conformity therewith, an interrupter contact combined with the said vibratory device, ,an electric circuit controlled by the said contact and adapted to produce electric oscillations of high frequency, this circuit being coupled with an outgoing line and a transmitting device which leads signal or speech currents into the said circuit in such a manner that these currents are divided into impulses by the said interrupter-contact and thereby made capable to put into operation the oscillatory circuit which then on its part sends high frequency currents corresponding to the signal or speech currents into the line, substantially as described.

2. High frequency generating system consisting of an acoustic device which produces air-waves of a frequenc over 4000 p. sec., a vibratory-device actec upon by the said air-waves and being capable to vibrate in conformity with a higher harmonic of the fundamental air-waves blown at the acoustic device, an interrupter-contact combined with the said vibratory device, an electric circuit controlled by the said contact and adapted to produce electric oscillations of high frequency, this circuit being coupled with an outgomg line, and a transmitting device which leads signal or speech currents into the said circuit in such a'manner that these currents are divided into impulses by the said interrupter-contact and thereby made capable to put into operation the oscillato circuit whlch then on its part sends hig frequency currents corresponding to the signal or speech currents into the line, substantially as described.

3. High frequency generating system consisting of an acoustic device which produces air-waves of a frequency over 4000 p. sec., a vibratory-device acted upon by the said air-waves and being capable to vibrate in conformity with a higher harmonic of the fundamental air-wave blown at the acoustic device, acoustical means laced in the path of the air waves from tie acoustic to the vibratory device and adapted to select a higher harmonic and to reinforce the action of the same on the vibratory device in combination with an interrupter-contact.

4. High frequency generating system consisting of a Galton whist e which produces air-waves of a frequency over 4000 p. sec., a 'ibratory device acted upon by the said airwaves and being capable to vibrate in conformity therewith, an interrupter-contact combined with the said vibratory device, an electric circuit controlled by the said contact and adapted to produce electric oscillations of high frequency, this circuit being coupled with an outgoing line, and a transmitting device which leads signal or speech currents intothe said circuit in such a man-' nor that these currents are divided into impulses by the said interrupter-contact and thereby made capable to put into operation the oscillatory circuit which then on its part sends high frequency currents corresponding to the signal or speech currents into the line, substantially as described.

5. High frequency generating system consisting of an acoustic device which produces air-waves of a frequency over 4000 p. sec., a microphonical diaphragm contact acted upon by the said air waves and being capable to vibrate in conformity therewith, an electric circuit controlled by the said contact and supplied with electrical oscillatory means, these means being coupled with an outgoing line, and a transmitting device which leads signal or speech currents into the said circuit; in such a manner that these circuits are divided into impulses by the said diaphragm contact and thereby made capable to put into operation the oscillatory circuit which then on its part sends high frequency currents corresponding to the signal or speech currents into the line.

6. High frequency generating system consisting of a Galton whistle which produces air waves of a frequency over 4000 p. sec., a diaphragm acted upon by the said air waves and being capable to vibrate in conformity therewith, a contact pin bearing against the said diaphragm, an electric circuit controlled by the touching spot between the diaphragm and the contact pin, and supplied with electrical oscillatory means, these means being coupled with an outgoing line, and a trans- .mitting device which leads signal or speech quality being applied to the point of the contact pin, in combination with an electric circuit.

8. High frequency generating system consisting of a Galton Whistle which produces air waves of a frequency over 4000 p. sec., a microphonical diaphragm contact acted upon by the said air waves and adapted to vibrate in conformity therewith, the said diaphragm being located aside the mouth a of the Galton whistle, means for varying the distance between the whistle mouth and the diaphragm, an electric circuit controlled by the said diaphragm contact and adapted to produce electric oscillations of high frequency, this circuit being coupled with an outgoing line, and a transmitting device which leads signal or speech currents into the said circuit in such a manner that these currents are divided into impulses by the said interrupter contact and thereby made capable to put into operation the oscillatory circuit which then on its part sends high frequency currents corresponding to the signal or speech currents into the line, substantially as described.

. 9. High frequency generating system consisting of a Galton whistle which produces air waves of a frequency over 4000 p. sec., :1 microphonical diaphragm contact acted upon by the said air waves and adapted to vibrate in conformity therewith, the said diaphragm being located aside the mouth of the Gallon whistle, an. acoustical reflector mounted opposite the diaphragm at the other side of the whistlefmouth, means for varying the distance between the said reflector and the diaphragn'i, an electric circuit controlled by the said diaphragm contact and adapted to produce electric oscillations of high frequency, this circuit being coupled with an outgoing line, and a transmitting device which leads signal or speech currents into the said circuit in such a manner that these currents are divided into impulses by the said interrupter contact and thereby made capable to put into operation the oscillatory circuit which then on its part sends high frequency currents corresponding to the signal or speech currents into the line, substantially as described.

10. High frequency generating system consisting of an acoustic device, which produces air waves of a frequency over 4000 p. sec., a vibratory device acted upon by the said air waves and being capable to vibrate in conformity therewith, an interrupter contact combined with the said vibratory device, an electric circuit controlled by the said contact and adapted to produce electric oscillations of high frequency, this circuit being fed with a steady weak continuous current and coupled with an outgoing line, and a transmitting device which leads speech currents into the said circuit in such a manner that these currents are divided into impulses by the said interrupter contact and thereby made capable to put into operatlon the 0seillatory circuit which then on its part sends high frequency currents corresponding to the speech current into the line, substantially as described.

WILHELI EDUARD ERICII HABANN.

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