US1457069A - Receiving system for electric waves - Google Patents

Description

L. LEVY RECEIVING SYSTEM FOR ELECTRIC WAVES .Ewen-tor: ucc'en Leva May 29, 1923.

L. LEVY RECEIVING SYSTEM FOR ELECTRIC WAVES Filed Sept. 27 1919 5 SheetsSheet 2 mill Y E Uf @Juf May 29, 1923. 1,457,069

L. LEVY RECEIVING SYSTEM FOR ELECTRIC WAVES Filed Sept. 27 1919 5 Sheets-Sheet 3 /Pece/r d ,F1g, 6. /1/"9v fre enc 9' .y Carr' nfs.

f\ N 71m@ fer /Hf MIO/KH 5 Sheets-Sheet 4 May 29, 1923.

L. LEVY RECEIVING SYSTEM FOR ELECTR'LC WAVES Filed Sept. 27 1919 50 ing selector circuits .and tuned to i a fre- Patented May-29, 19213.`

UNITED STATES LUCIEN- LEVY, OF PARIS, FRANCE'.

RECEIVI G SYSTEM FOR ELECTRIC WAVES.

Application led-'Se'p'tember 27, 1 919. Serial No. 328,993.'

To all whom it may concern Beit known that I, LUGIEN LEVY, o-f 58 Rue depVerneuil, Paris, France, have invented a Receiving System for Electric Waves, of which the following is a full,

clear, and exact description.

In the specification of patent application Serial No. 249.572, filedv August l2, 1818, the applicant hasA described a system of electric -transmission at a distance, applicable to wireless telegraphy' and telephony andv comprisin a special'transmitting station device an a specialv receiving station device.

In this patent it was specified that this receivin 'station device could 'be combined witha Iocal generator ermitting it to receive the ordinary Vemissions of the continuous wave 'stations under suflicient con- 'ditions of selectivity in spite of the. disturbances of spark stations or atmospheric parasites.

' In the case of this` latter application, the receiving system comprising as its essential characteristics as has been stated in the patent, the following elements l. Receiving circuits ordinarily employed or primary detecting selectors tuned to the fre uency of the continuous wave to be. received.

v2. A local generator of high frequency coupled to the primary detecting selector circuits and'tuned to a frequency different from that ofthe continuous wave to be ,re-

ceived, the difference in the numbers of- 'periods per second. being a high number (of the order of 10,00() for example) so as to produce ultra-acoustic beats at a high frequency generally -inaudible by the 'coin- 40 bination. in the primary. detecting-selector circuit of the two induced currents, the one by the aerial receivingcircuits of the con'- tinuous wave'and ,the other bythe local generator.

3.A Secondary detecting selector circuits tuned tothe frequency ofthe ultra-acoustic beats. l

4. A current generator of ultra-acoustic` A. frequency coupled to the secondary detectquency near to the ultra-acoustic frequency of the above mentioned' beats, in' such a, way that there are produced,` in thel second.;`- ary detecting selector circuits, beats of frequency.

acoustic frequency Aby the combination of the two currents" of ultra-acoustic frequency.4

5. If necessary selector circuits tuned to the frequency of acoustic beats.

The presentapplication has4 for its object an improvement made in the receiving system described in the original application ofthe applicant in the case'oflits application to waves emitted by ordinary stations, for the purpose of obtaining a more Complete. selectivity and a greater protection against atmospheric parasites.

These improvements consist in 1. A special method of secondary'selection based on the original principle described and comprising also various complementary operations intended to ensure efficient working of the system in all cases,

even when the parasitic disturbances 0r confusion are very intense'. v

2. Arrangements which permit of the practical carrying out of the improved method and ensuring very great sensitiveness of the system.

The present improved'method comprises,

`b`roadly,'the following operations consistinfr:

In producing in the primary ldetecting selector circuits, before t e first detection, beats of adjustable amplitude and of adjustable ultra-acoustic frequency (of the order for example of `10,000 per second) between the currents induced in the circuits by the oscillationsl of the receivin antenna and the current .which isfinduce by a 'local generatorof high frequency.

2.In' amplifying and :then detecting these beats in'a' detecting amplifier of high 3. In separating the numerous periods nished by the detection of the -beats of the continuous wave, from some periods of limited amplitude and very small innumber', `(one or two furnished by parasites) and fro'mthe currents of low frequency coming .of currentofultra-acoustic frequency furfrom the succession of the parasites: this selection taking place 'in a secondary selecjtor'- the working vof which, is based generally on the known phenomena of propagation of electric waves of s stems with capacities and self inductors distributed in a relatively small number of elements;

4. In amplifying the selected currents of ultra-acoustic frequency and in transforming them into current of acoustic frequency by causing them to beat with a local current of ultra-acousticfrequency and then in detecting the beats obtained.

5. In effecting a selection on the acoustic frequency.

The production of the beats of high ultraacoustic frequency in the primary selecting circuits is obtained by coupling inductively or by any method either to the receiving antenna, or to the primary selecting circ-uit coupled thereto, or to one of the circuits of the amplifying arrangements for the high frequency currents received by the antenna, a local generator of high frequency, the frequency of oscillation of which is chosen in such a. way as to differ from the frequency of the receiving station (at which the primary selecting circuits are adjusted) by a number of periods per second equal to the ultraacoustic frequency to be obtained.

The present Inode of secondary selection is applicable likewise to the primary selection and to the acoustic selection.

The accompanying drawing shows by way of example an installation which permits of the carrying out of the present invention.

Figures 1 and la show an antiparasitic receiving station of high selectivity for the reception of continuous waves.

Figures 2 and 3 represent modifications of detail.

Figures 4, 5,;6, 7, 8, 9, 10, 11, 12, 13 and 14 represent diagrammatic representations of the currents in the different system.

In the method of carrying out the invention shown in Figure 1. the receiving station comprises:l

1. A ,primary selector constituted by receiving circuits similar to those ordinarily employed in wireless telegraphy and comprising a self inductor 1 connected on the one hand to the antenna 7 and on the other hand to the earth 8 with the interposition of the non-inductive resistance 106. This self inductor is coupled by induction to the oscillating circuit 2, 3 relatively damped.`

2. An amplifier and detector of high fregxuency renresented between the terminals B and i, D and comprising three vacuum tubes 4, 5, 6 mounted so as to eXert successively an amplifying and detecting action on the high frequency currents.

The filaments 11, 14, 17 of these three tubes 4, 5, 6 are hea/ted in parallel by the accumulator 49.

' The three plate filaments circuits of the three tubes are s plied by one andthe same plate batteryg.

The grid 12 and the filament 11 of one i tube 4.are connected respectively to the two terminals A, B of the oscillating circuit 2,

parts of the- 3 and a resistance of high value 20 is placed in shunt between 11 and 12.

In the plate circuit of the tube 4 is interposed the primary winding of an autotransformer 23 of low? distributed capacity and which can be provided or not with a finely laminated iron core. In the case in which no core is provided, this bobbin will be constituted for example by a spiral winding in several layers of wire preferably of copper, as fine as possible with comparatively thick insulation.

The grid 15 of the tube 5 is connected to the secondary winding of the auto-transformer 23 passing through a condenser 24 of low capacity.

The plate 16 is connected to the battery 25 passing through the primary winding of an auto-transformer 26 which may or may not have a core of finely laminated iron and is constituted ifA necessary in a manner simi'- lar to the bobbin 23: the secondary winding of this auto-transformer is constituted by the whole of the winding of the bobbin, although the primary winding thereof comprises for example only half.

The grid of'the tpbe 6 is connected to the secondary winding of 26 through a condenser 27.

The auto-transformers 23, 26 might be replaced by choking coils.

The plate 19 and the battery 25 are connected respectively to the two terminals C, D on which is.mounted the secondary selector, as will be hereinafter described.

3. A local generator of high frequency l constituted for example by the vacuum tube 10 mounted as a generator of oscillatlons by magnetic coupling of the self `inductors 44 and 45. Between the plate and the grid of this tube is mounted a variable condenser 43. Between the self inductors 44 and 45 is interposed a condenser of large capacity 46. A coupling coil 9 is interposed in the oscillating circuit 43, 44, 45 the proper oscillations of which are kept up by the tube 10.

The oscillating circuit 43, 44. 45, 9 is tuned to a frequency which is different from the individual frequency of the circuit 2, 3 by a high number lof periods per second (for example of the order 10,000). The bobbin 9 is coupled inductively either to the self inductor 1, or to the self inductor 2, or to the self inductors 23 or 26.

The coupling between the oscillation generator and the primary selecting circuits may be effected by any well known means 0f coupling and take place at any point of the circuit from the antenna up to the primary winding of the auto-transformer 26 inclusively, that is to say before the primary detector 6.V

4.v A secondary selector properly so called or filter.

This secondary selector comprises a succession of condensers 34 mounted in series and self induction coils 33: the ends of these coils are connected respectively, some to the connections connecting the successive condensers the others to a common conduc tor 49 connected to earth.

These condensers and self inductors are designed so as to fulfil the following conditions: Y

(a) the whole offers a minimum of impedance for the ultra-acoustic frequency equal to the difference of the individual frequencies of the circuits 2, 3 and 43, 44, 45:

(b) the values of the condensers and of the self inductors are determined in such a way that at a given instant the currents distributed over the selector traverse a group of successive condensers in one direction and the next group in the reverse direction, and these currents of ultra-acoustic frequency change their direction at intervals comprising n condensers n being any member from 2 to 6, and 6 in the example shown in the drawing, that is to say that nodes of current are produced in this case and in permanent state approximately every six condensers.

The extrelne self inductors 338L and 33" have generally ay value which is double that ofthe self inductors 33. The two ends of the self inductor 33 are connected to the-terminals of the secondary winding 29 of a step down transformer 30 the primary winding of which is branched between the terminals C, D.

A lvariable condenser 31 is preferabl interposed between the terminal 126 o the secondary winding of this transformer and the terminal 127 of the self inductor 33".

On the section of the line connecting the two condensers 34, 34", between which is produced a change of direction of the current, are mounted in series two self inductors 36, 38 arranged on either side of the self inductor 33".

These two condensers 34, 34" have a capacity which .s less than that of the condensers 34. The self inductor 33" similar to the self inductors 33 is coupled to a self inductor 35.

Two self inductors 37, 39 coupled respectively to the self inductors 36, 38 are mounted in series with the self inductor 35 and a self inductor 40 on the terminals of a variable condenser 41.

The oscillating circuit 35, 37, 39, 41, 40 must have the minimum of damping possible' and is tuned ap roximately to a frequenc equal to the ifference of the individua frequencies of the oscillating oircuits 2, 3, and 43, 44, 45, 49, that is to say to a frequency of the order of 10,000 for exam le.

'Illie system of self inductors 33, 33, 33", 33", 36, 38 and the condensers 34, 34", 34"

constitutes an artificial inverse line. This latter may comprise a different number of elements.

5. A resonance detecting selector amplifier generator for low frequency constituted by a certainnumber of three electrode vacuum tubes, 53, 54, 55, 56, 57, 58 the filaments of which 59, 62, 65, 68, 71, 74 are heated in parallel and the plate filament circuits-0f which have the plate battery 92 in common.

The terminals E, F of the oscillating circuit, 35, 37, 39, 41, 40 are connected respectively to-the grid 60 and to the filament 59 of the tube 53, with the interposition of a stop condenser 83 and the arrangement of a large resistance 77 between 59 and 60.

The plate 61 of this tube 53 is connected at an intermediate point 50 to a self inductor 93 of low distributed capacity and which may be or may not be provided with a finely laminated core of iron. The plate circuit 61, 50, 105, 92 of. this tube 53 passes through the primary winding 50 105 of the autotransforming self inductor 93 and, through the battery 92, the secondary winding 93 of this auto-transformer is in parallel with a condenser 94, the connection 205 being connected to the grid 63 of the tube following (54) passing through the stop condenser 84 of this latter, the connection105 being connected to the filament 62 of this tube by way of the battery 92. As before, a large resistance 78 is arranged in'. shunt between 63 and 62.

The same system of connection which has just been described between the plate circuit 61, 93. 105, 92 of the tube 53 and thel grid circuit 63, 84, 106, 105. 92, 62 of the next tube 54 is reproduced between, the following tubes.

The oscillating circuits 93-94, 95-96,

97-98 are tuned to a. frequency which is near to that of the frequency of the ultraacoustic beats. l

The stop condensers 85 and 86 of the tubes 55, 56 have a capacity near to that 0f the stop condenser 84; however, the capacity of the i condenser 86 is slightly smaller, and the large resistances 79, 80` 81, 82 corresponding to the tubes 55, 56, 57, 58 are similar to the resistance 70.

In the plate circuit of this last tube 58 is interposed the receiving telephone 104 shunted by a condenser 103.

The two oscillating` circuits 99, 100 and 101, 102 of the tubes 57 and 58 are tuned for an acoustic frequency nea-r to the maximum of sensitiveness of this telephone 104. The self inductors 99 and 101 are generally iron cored.

The stop condensers 87 and 88 present for the current of acoustic frequency an impedance of the same order as that of the condenser4 84 Vfor the current of ultra-acoustic frequency.

Working.

In Figures 6, 7, 8, 9, 10, 11, 12, 13, 14 is shown the curves of the variations of the currents circulating in different parts of the circuits in action at the same time the time being denoted by the abcissae and the currents by the ordinates.

Under the action of a continuous emission to which the antenna is tuned, the self inductor 1 is traversed by an alternating current of high frequency 1112, (see Figure 6) simultaneously, damped alternating currents 107a` arising either from the individual oscillation of theantenna under the influence of parasitic shocks highly damped or of the induction lwaves having the same period as that to which the antenna is tuned, circulate in this self inductor.

These currents induce yrespectively in the oscillating circuit 2, 3 Awhich is suitably damped currents of which only a few eriods and their envelope are shown (Fig. 7). These induced currents are:

1. A sinusoidal alternating current 111b the envelope of which is 111.

2. Damped currents, such as 107b with envelopes 107, 108 arising from parasitic shock or damped emitting stations.

3. Furthermore in this circuit, the generator 10 induces the alternating sinusoidal current 110b the frequency of which differs from the frequency of the current 111b by a number-of periods corresponding to an ultra-acoustic frequency. The current which circulates in the circuit, 2, 3 results from the vcomposition of the three currents above enumerated. l

The composition of the currents 110b and 111b is indicated in FigureB. In this figurelis shown the production of beats 112b of mean ultra-acoustic frequency by the combination of the current coming from the continuous wave station with the current coming from the local generator.

'ilhe figure represents the case in which the), continuous wave has a frequency of 60,000 periods per second. The generator 10 induces a frequenc of 70,000; 10,000 beats per second are pro uced.

The parasite current 111 being of short duration can only give at the maximum one or two beats to 10,000 periods, the amplitude of these beats being adjustable and having for their maximum amplitude that of the current induced by the localY generator.

Furthermore, it is important to note that the amplification relatively due to the action of the local generator is, infinitely greater for the feeble continuous wave station than for the strong parasite and can be adjusted to the maximum value by variation of the v amplitude of vthe oscillations induced by the lcal generator.

Y These beats and currents of high frequency iaezoea are amplified by the tube 4 the plate circuit of which is traversed by identical currents. The high vfrequency potential differences which develop at the terminals23 are transmitted by the condenser 24 to the grid of the tube 5.

In like mannerthe currents and beats of high frequency amplified which circulate in the primary winding of 26 are transmitted to the grid 18 of the tube 6 which acts as a detector in a manner well known. It, should be noted that a portion of the energy of the parasite current had been absorbed by a first detection due tothe tube 5, although the continuous wave of much lower intensity was transmitted without detection.

The plate circuit 19, C, D, 25, 17 of the tube 6 is traversed by the currents coming from the detection of the high frequency currents and beats.

Fi ures 9 and 10 indicate the effect produce by the parasite, and Figures 11 and 12 that produced at the station by continuous waves 111b of Figure 7.

For the sake of clearness in the drawing, the two currents, one of which is due to the parasite and the other to the continuous wave, have been separated.

In reality these two currents are superposed. v

The line 113 represents the permanent current in the plate circuit.v The line 110c represents the effect of the local generator on the current of the plate circuit. The line 114b represents the effect of interference between the parasite and the local generator. The line 115 represents the variation of the permanent current dueto the charge of the condenser 27 under the effect of the train of parasitic waves.

It is easy to ascertain that the cu-rrents, circulating in the plate circuit 19, C, D, 17 under the influence of parasites and becoming superposed on the permanent current, maybe decomposed into:

1. Impulses such as 115 having a relatively large duration with respect to the ultra-acoustic period and succeeding each other at a low trequency.I

2. A current period ofyultra-acoustic frequency 116 (see Figure 10) having a limited amplitude, whatever be the magnitude of the parasite, of a value which is adjustableby variation of the coupling between the bobbin 9 and the self inductor 2.

3. A train of high frequency waves.

The etlect of the combination of the continuous waves station andthe local generator is represented in Figure 11 at 117".

The current circulating in this same plate circuit under the influence of the continuous wave station is composed:

.1. of a change of the mean current 122 corresponding to each signa-l.

2. of an alternating current of ultrastrongly throttled by the iron self inductor 28.

In the case in which the high frequency of the waves received is very high and, consequently very different from the ultraacoustic frequency, the self inductor 123 may be dispensed with.

Under these conditions, only the currents of ultra-acoustic frequency and low frequency pass into the transformer C, D.

Figure 13 shows quite diagrammatically the difference of potential 119, 120 at the terminals of 29 under the effect of the parasite, and Figure 14 shows at 121 that corresponding to the continuous wave.' Experience has shown that it was useless to try to separate the effect of violent parasites from that of the continuous wave by constituting the secondary selector of an oscillating circuit. This latter as a matter of fact is excited by shock under the influenceof the low frequency current 120, which transforms each parasitic shock into ultra-acoustic current, so that the elimination of parasites is not effected. It is therefore indispensible to have recourse to'new methods of selection derived from a modification considered in the original patent and constituting an efficient secondary selector.

Under the effect of the alternating current 121 supplied by 29 on the system of self inductors and distributed capacity 32, 33, 34. 35` 36, 38.52, 50 constituting an artificial inverse line, stationary waves are produced, when this system is timed to vibrate in resonance with the ultra-acoustic current furnished by the continuous Wave station.

The line` 124 represents the current traversing the condensers 34 and the conductors which connect them, the line 125 represents the potential along the line. For example the arrows 132, 133 indicate the values of the currents between the terminals 127, 128, and the terminals 128, 129, respectively, while the arrows 134a and 135b indicate the E. M. F.s across 127, 49, and 128, 49 respectively and so on.

The line 135 represents diagr-ammaticaliy and generally, stages having been eliminated, the distribution of the current over. a 5/4 wave line at the instant the current is greatest, when the permanent state is estab.

lished, the Wave length being defined as the constant distance reckoned on the line (by the number of meshes for example) between two points where the current and the tension have the same value and the same direction.

The currents at different points of the line (which flow through condensers) are in phase and have a lead of approximately 90 degrees to `the potentials at the same points (measured on the coils).

On the contrary, the parasite cannot give stationary Waves since it produces only one period of ultra-acoustic current. A free Wave is propagated over the inverse artificial line in such a way that the potential varies at each point in phase with the current. The line 137 representing the current at a given instant, the distribution of the potential is 136. Under these conditions, if the coupling' 39, 38 be reversed with respect to the cou-.

pling 37, 36, a tension in phase with the. tension at the terminals of 35 will be obtained over the whole 37 39. These two tensions may be opposed for a. suitable choice of the direction 0f the coupling 35, 52 in the case of the free Wave. For the stationary' wave on the contrary, the two tensions induced being put out of phase by 90 degrees will be added geometrically for the same arrangement of the couplings. -The ultra-acoustic effect of the parasite on the oscillating circuit 35 37, 39, 4.1, 40 may be cancelled although the ultra-acoustic effect of the continuous wave v station will be au mented On the otherv and, the current of low frequency due to the parasite will not be able to propagate itself over the line: the

wave length of the parasite current which` is proportional to the square of the frequency being small for low frequenciesonly covers a small number of condensers. Under these conditions, there is reflexion of the low frequency current and enormous weakening of the said current along the line.

All the effects of the parasite being annulled, there only remains those of the continuous Wave station which causes the circuit 35, 37, 39, 41, 40 to oscillate.

The oscillations of this circuit are amplified by means of the three vacuum tubes 53, 54, 55, the oscillatingcoupling circuits of which 93-94, 95-96, 97-98 are slightly put out of tune with the frequency of the circuit 35, 37, 39, 41, 40. Good experimental results have been obtained with the condensers 94, 96, 98 being greater than the value of resonancev and increasing in this order. Under these conditions, the system, due particularl to light magnetic couplin between the di erent circuits, starts to osci latek at an ultra-acoustic frequency slightlyv isc different from that of the current of the continuous wave station. There is produced by the combination of the current engendered by the oscillation proper to the system and that arising from the transformations of the continuous wave, beats of acoustic frequency which are detected, by the tube 56 and transformed into current of acoustic frequency. It should be noted: 1. that this system which is auto-excited and of ultra-acoustic frequency possesses a much greater receiving sensibility for feeble vcurrents than for strong ones, which is very favourable to the reception from feeble stations: 2. that the acoustic beats can always be limited in amplitude.

This acoustic frequency being adjustable by variation of the high frequency induced by the generator 10 in Figure 1 can be brought to be the frequency of resonance of the circuits 99-100 and lOl-102 and of the telephonic headpiece (104) which might be replaced by a resonance galvanom'eter.

If the circuits 93, 94*95, 96-97, 98 are sufficiently damped (for example by taking resisting self inductors or by varying the heating of the filaments by the rheostat 90) no ultra-acoustic oscillations will be generated. In this case, the circuits 93-94, 95 96, 97--98 are tuned to the ultra-acoustic frequency of the circuit 35, 37, 39, 4&1, 40.

In the case of the reception of continuous waves coming from a wlireless telephone station, the"l acoustic selection is dispensed with, the condensers 100, 102, cut out by switches 140 and 141, and the autoexcita+ tion of the amplifier done away with by reducing the heating by means of the rheostat 90.

Finally, it is .possibleto replace the local heterodyne generator 10 by an auto-excitation at high frequency (auto dyne) of the detecting amplifier AB, CD obtained by causing the amplified currents to act on the oscillating circuit 2, 3 for example by a magnetic or electric coupling of the circuits in which these `currents circulate with the circuit 2, 3.

Figure 2 represents a modification in which a transformer (an iron cored one for example) has been interposed between the oscillating circuit and the first grid so as to damp this circuit by a greater consummation: of energy of the grid circuit of the lamp 4.

The inverse artificial line arrangement employed for the secondary selection may likewise be employed:

1. for the primary selection and for the acoustic selection and generally every time there is a question of separating a disturbance of an alternating current the period of which is shorter than the duration of the disturbance.

2. vfor the separation 0f a train of waves of some periods from a train of waves constituted by a large number of periods.

For the latter purpose, it is important to note that in place of employing an inverse artificial line as described and shown in Fig. 1, a direct artificial line inightbe employed this line being constituted by transposing in the inverse artificial line the self inductors 33 and the capacities 34 or even other systems more complicated without changing the spirit of the invention.

Figure 3 shows the arrangement on the antenna of a device intended to reduce considerably the excitation by shock of the antenna to the frequency of the wave for which the whole of the apparatus-is adjusted. As will be seen from the diagram, thel same arran ement of inverse artificial line is employed as for 'the seconda-rv selector. F ig. 5 indicates diagrammatically the distribution of the current excited in the antenna by the receiving continuous wave station.

In Figure 3. an inverse artificial lines' has been arranged in series with the antenna for the purpose of diminishing the propagation, over the antenna and artificial line system, of electric shocks having a duration longer than the period over'which the system is regulated and which it is intended to receive.

If on the contrary it was desired to be protected against shocks of shorter duration `than this, it would suliice to place in series `with the antenna an ordinary direct artificial line.

Furthermore, instead of putting these lines in the lower part of the antenna, even fthe elements of direct and inverse artificial lines might be distributed over the antenna.

More complicated combinations', of direct and inverse lines may also be utilized without changing the spirit of the. invention, the characteristic point of this part of the invention being the fact that for the frequency to be selected the number of condensers or self inductors per wave length is small, of the order of 9 for example, but more than 3, while for any'electric shock of a duration different from the period to which it is tuned, the number of elements per wave length being less than 4, for example, the propagation is effected with very great weakening.

Claims:

1. In an antiparasitic selecting receiving system for electric waves means for selectively receiving on one vtuned device electrical oscillating damped energy as well as sustainedy energy of the same primary frequency,means for converting the frequency of this energy to lower but ultraacoustical 'frequency energy,-means for separating 1n the ultra-acoustical frequency energies the sustained energy from the damped ener ultra-acoustica energy for actuating the indicating means of the receiving station.

2. In an antiparasitic selecting receiving system for electric waves:-means for selectively receiving on one tuned device electrical oscillating damped energy as Well as sustained energy of the same primary frequency,-means for converting the fre'- quency of this energy to lower but ultraacoustical frequency energy,-means for separating in the tra-acoustical frequency energies the sustained energy from the damped energyf-means for amplifying and transforming this ultra-acoustical energy into an acoustical frequency ener and utilizing it for actuating the indicating means of the receivin station.

3. In an antiparasitic selecting receiving system for electric Waves: means for selectively receiving on a resonant device long Wave-trains of any frequencyand for attenuating the propagation on the system of short wave-trains of the same frequency or of electrical impulses,means for amplifying and converting the received currents' into currents of lower but ultra acoustical frequency, which frequency may be predetermined-means for effecting a secondary selection on the ultra acoustical frequency locally created by the transformation of the current issuing from the transmitting station and for eliminating the currents produced by the confusingstations and the parasitic signalsmeans for amplifying and transforming this current into an acoustical frequency current and utilizing it for actuating the apparatus of the receiving station.

4. In an antiparasitic selecting receiving system for electric Waves: means lectivelyk receiving on tuned devices constituting a primary selector, waves of any frequencys-a local generator of high frequency current coupled to the circuits through which iow the primary high frequency current and producing ultra acoustical beats,-a primary detector-amplifier coupled to the primary selector, amplifying the beats and high frequency currents and transforming them into ultra acoustical frequency currents,-a secondary choke se lector tuned to the ultra acoustical frequency and comprising an artificial line separating the ultra acoustical current issuing from the transmitting station currents, from the parasitic or confusing signals, means for amplifying the selected ultra acoustical current and transforming it into acoustical frequency current, and an indicating member actuated by this acoustical current.

5. In an antiparasitic selectingy receiving system particularly adapted to radio-telephony and telephony,-'means for selectively receiving on tuned devices constituting a primary selector, waves of any frequency,-

for se- ,--meansv for utilizing the a local generator of high frequency current coupled to the circuits through which flowA the primary high frequency current and producing ultra acoustical beats,-a primary detector-amplifier coupled to the primary selector, amplifying the beats and high frequency currents and transforming them into ultra acoustical frequency currents-a secondary choke selector tuned to the ultra acoustical frequency and comprising an artificial line separating the ultra acoustical current issuing from the transmitting station currents, from the parasitic or confusing signals,-means for amplifying the selected currents and transforming .them into currents to the voice frequency,-

a receiving apparatus of low frequency current.

6. In a selecting receiving system means for transforming the received current into asuccessior of predetermined frequencies current Aissuing successively from each other a plurality of oscillating circuits tuned tothe predetermined frequencies and means-for tuning, by only one adjustment simultaneously, of all the frequencies locally created on the predetermined oscillating circuits.

In a selecting receiving system in combinationz-a receiving circuit adjustable to any frequency,-an heterodyne generator adjustable to other frequencies for giving predetermined secondary frequency beats,- a plurality of circuits tuned to predetermined frequencies the first being tuned to the secondary frequency,-a generator tuned once for all on another secondary frequencly for giving tertiary frequency beats.

8. n a selecting receiving system .in com'- bination:-a recelving circuit adjustable to any primary frequency,means for converting the primary frequency in a predetermined secondary frequency,-an auto-excited circuit tuned to the secondary `frequency and generating oscillation to another predetermined secondary frequency for producing tertiary frequency beats between the twov predetermined secondary frequencies. j

9. In a selecting receiving' system:- means for transforming areceived current of any frequency into a predetermined fre- .quency current,-a plurality of oscillating circuits tuned to this predetermined freuency for amplifyingselectively this preetermined frequency,and means for obtaining the tuning by one adjustment by varying the frequency produced by the convertin device.

10. n a selecting receiving system, primary selecting circuits tuned to the frequency of the Wave to be received,a local /generator of high frequency current causing the production of predetermined ultra acoustical frequency beatsmeans for am- .the production. of predetermined ultra4 acoustical frequency beats,--means for amplifying and detecting these beats and transforming them into ultraacoustical frequency current,means previously tuned to the predetermined ultra acoustical frequency for selecting, amplifying and transforming the ultra acoustical lfrequency current into predetermined audible frequency current.

l2. In a selecting receiving system 'for electric Waves a selecting system for separating'an impulse or damped -Wave-train from a long wave-train comprising in combination z-an artificial line constituted .by im- -pedanceshaving such values that the line is tuned on the frequency to select, and betubes, comprislng, betweenl the grid and ing'in such number thatthe line comprise a number of Wave-lengths greater Vthan they number offperiods of the damped Wavetrain,means for separating' the free wave caused bythe impulse or the short wavetrai-n propagating on the artificial line frein the stationary Waves which' are produced therein -by the long Wave-train.-

13. In a selecting receiving system, forA electric Waves a selecting system for separatinfr an impulse -or damped Wave-train from a ongWave-train comprising in combination :-an artificialline-constituted by impedances having such values thatthe lineis tuned on the frequency to select, and that the number of elements by Wave length is small and being in such number that thelin'e comprise a number of Wave lengths greater than the number of eriodsof the damped Wave-train,-means or separating-the free Wave caused by the impulse or the short Wave-train propagating on the artificial line from the stationary waves which are produced therein bythe long wave-train.

i4. In aselecting receiving system for electric Waves a selecting system for separat'- in an impulse or damped wave-train from a long yWave-train comprising in combinaof thefollbwing tu tion -an artificial line constituted by pedances having such values that the Ime 1s tuned on the frequency to select, and being in such number that the line comprise a number of Wave-lengths greater than the number of ,periodsof the damped 4Wavetrain,-a circuit coupled with different element of the artificial line for obtaining a balancing for free waves and not for stationary Waves 15.' In a receiving device for electric Waves, a multi-step medium and low frequency detector-selector-ampliier provided with vacuum tubes, comprising, between the plate and grid-circuits of two consecutive tubes, selecting oscillating circuits, a portion of the self--induction -coil'of each oscillating circuit being included in the platecircu-it of 'one of the tubes, the free end of this coil being connected to the grid of the next tube Vthrough acondenser, these oscillating circuits belngtuned to ultra acoustical frequencies beforethe detecting tube and to acoustical frequencies after this tube and a `plate-battery and a heating accumulator common to the ultra` acoustical current amplifying tubes and the acoustical current amplifying tubes. i, v

1 6, In a receiving device for electric Waves, a medium and low frequency detector-selector-amplifier provided with vacuum plate-circuits of .two consecutive tubes, selectin oscillating circuits, a" portion of the self induction coil'of each .oscillating circuit being included in the plate-circuitof one .ofthe'tubes the free end of this self indu-@tion coil-bein connected to the grid through a condenser, these oscillating circuitsV being tuned to ultra acoustical, predetermined frequencies, before the detecting tube and to acoustical frequencies after thesa-id tube,-a platebattery and a heating accumulator common to theultra acoustical current amplifying tubes and the acoustical'current amplifyingy tubes,-1neans for producing an auto-excitation of the first tubes on a frequency slightly different fromA the ultra acoustical frequecy vto be amplifed, these tubes acting as auto-generators of ultra acoustical frel quency current, for the urpose of producing acoustical frequency eatsand of transformingl the ampllfied ultra acoustical current into audible frequency current.

The foregoing specification of my receiving system for electric Waves, signed by me this 8th day of September 1919.

LUCIEN LEVY.

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