US1917995A - Radio telephony - Google Patents

Description

H. S. POLlN RADIO TELEPHONY July 11, 1933.

Filed May 21, 1929 5 Sheets-Sheet 1 a gmemtoz ElrZe rilifgliw,

H. S. POLIN RADIO TELEPHONY July 11, 1933.

Filed May 21, 1929 5 Sheets-Sheet 2 ,Lmhkm WLMAINW H. S. POLIN.

RADIO TELEPHONY July 11, 1933.

Filed May 21, 1929 5 Sheets-Sheet 3 H. S. POLIN RADIO TELEPHONY July 11, 1933.

Filed May 21, 1929 5 Sheets-Sheet 4 gwmnto'o July 11, 1933. s, POLIN 1,917,995

RADIO TELEPHONY Filed M ,21, 1929 5 Sheets-Sheet 5 ml l l m" gwuomloc UN LWAQWMMWM Patented July 11, 1933 UNITED STATES PAT ENr- 'oFF- cE:

HERBERT S. POLIN, OF SAN FRANCISCO, CALIFORNIA, ASSEGNOR,.BY DIRECT AND' AIESNE A SIGHMENTS, T0 INTERNATIONAL RADIGPHONE CGRPORATIQN, OF WASH- ENGTON, DISTRICT OF COLUIQBIA, A CORPORATION OF BELAQVABE RADIO TELEPHONY Application area May 21,

My invention relates to automatic te1e phony.

More specifically, it relates to a system of means for tuning the telephone apparatus of the calling subscriber to the wave length of the subscriber called. r

Other objects and advantages of my invention will be apparent from the present specification in connection with the drawings attached thereto.

in said drawings:

Figure 1 is a diagram showing one type of circuit which may be used at the trans mitting end of a subscrihers station.

Figure is a diagram of a calling dial embodying variable condensers in its structure.

Figure 3 is a diagram showing, in front.

. e evation, some of the mechanical and electure as Figure 3, but with the parts in a different position.

Figure 3" is a section on line b7) of Figure 3.partiyin elevation.

Figure 3 is a diagram illustrating the operation of the contact arm shown at the right of Figure 3*. This figure is a section on line c-c of Figure 3", looking in the directi on of the arrows.

Figure 1 is a diagram showing an alter native circuit which may be employed, as the transmitting means.

Figure 5 is diagram of a circuitwhich may be used as the receiving means.

Figure 6 is a diagram of a portion of a 9 circuit which may be employed to actuate act .ductor24. Inasmuch as one part of the grounded part of 1929. Serial No. 364,838

is connected to, and formsa part of, the c1r'- cuit shown in Figure 5., and shows the connec trons relating to the relays V V and'V3. of

Figure 5.

Referring now specifically to Figure 1,

the transmitting portion of the subscribers station comprises a thermionic tube 16, hav' ing a cathode 18 heated by any suitable means 21, a grid 19 and a plate 20. A telephone induction coil or its equivalent; comprising coils 63 and 59 Wound upon core 62, is provided, the primary coil 63 being connected to the microphone 65 by means ofconductors 64 and 67-, a source of current 66 being interposed in conductor 67, as shown. One end of the secondary coil 59 is connected to the conductor 4-2, which is grounded at 60. The other end ofcoil 5 9 is connected to the grid v 19 through a path including conductor 58, grid leak 55, conductor 56, coil 23and 0011- cathode 18 is also connected to the ground through conductors 61, hland 60, this pro-- vides a circuit whereby any speech currents originating in-the micropho'necirc'uit will" produce potential variat1ons or" the grid 19 with respect to the catho'delS. A by-pass condenser 22 is connected to one end of the 1 coil 23 by means of conductor 56, and to the the cathode 18 through" conductor 57. i A dial 10, embodying in its structure a plurality of condensers 14, preferably ten in number to correspond to the ten digits of the arabic system of numbers, is connected into the circuit asfollows? Each condenser 14, here shown as a fixed condenser, has one terminal connected to the central shaft 118 of the dial, the other termi; als being connected to the ten contact points 31 arranged upon the periphery of the: dial,

as shown. Thesecontacts 31 are arranged scribed, to the stationary contact 25, connected to conductor 26 as shown. Assumin that such way that oscillations will be set up thereby in the well known way, the frequency being determined by the inductance of coil 23 and the capacity of the condenser 14 at that time in circuit.

The energy producing these oscillations is derived from the source of current 36, here shown as a high voltage B battery, although it will be understood that this showing is purely diagrammatic and any suitable source of power may be employed. 7

It willbe further understood that, while, for convenience of illustration, various distinct sources of current are shown, in practice many or all of these may be. combined so that all the power is derived from a single source, as is customary in radio circuits. This however, forms no essential part of the present invention, and many ways of accomplishing it are well know in the prior art. The negative terminal of the source of power 36 is connected to the cathode 18 by means of conductor 61, and the positive terminal leads to the plate 20 through coil 32 and conductor 26, as shown. A by-pass condenser 35 connects the terminals of the: power source 36 to each other through conductors 33, 34 and 61, as shown, and serves as a loweimpedance path for high frequency currents.

The coil 32 is coupled magnetically to coil 37, one end of which is connected to the grid 53 of a second thermionic tube 17, through the conductor 38, while the other end of this coil is connected to the cathode 52 of the tube by means of conductor 39, C battery 40 and conductors 41, 42 and 50, in the order named. The cathode 52 of this tube is energized by a source of power 51 in a usual way. The output circuit of the second tube 17, comprises a source of power 48 and a coil 45 connected inseries between the plate 54 and the grounded conductor 42, by means of conductors 46. 47 and 49, as shown. The coil 45 is coupled to a coil 43, which is located in the antenna circuit, comprising conductors 42 and 44 and the said coil 43.

A hook switch 28, controlled by the weight of a telephone receiver in the usual manner, is provided to close an alternative circuit between the grid 19 and plate 20 of the tube 16. this circuit comprising part of conductor 24. variable condenser 30, conductor 29, switch arm 28, contact 27 and conductor 26. The variable condenser 30 is mechanically controlled by means operated by the dial, which will be more fully described hereinafter, and indicated diagrammatically by the dotted lines in Figure 1.

The purpose of this arrangement is to adjust the rotor of condenser 30 into a position corresponding to the last digit of the sum produced by adding the digits of the number which has just been called by the calling subscriber. The purpose of. this arrangement will be discussed fully hereinafter.

Three different types of dials are indicated respectively at 10, Figure 1; 12, Figure 2; and 13, Figure 4. The dial 10, as already mentioned, comprises a plurality of fixed condensers 14 embodied therein; the dial 12 is similarto the dial 10, except that the condensers 15 embodied therein are Variable; and the dial 13 is the simplest of all, and comprises merely a single contact upon its periphery, .connected to the shaft 118by means of conductor 113. The purpose of the diaLof whatever type it may be, is to control the frequency of the radio energy emitted by the calling subscribers station during the signaling period. The dials 10 and 12 accomplish this by virtue of the variation of capacity which is produced in. the oscillating circuit upon the actuation of the dial, while dial 13, on the other hand, controls a set of crystal oscillators directly governing the frequency of the radio currents produced.

Each of these dials, 10, 12 or 13, regardless of its electrical differences, is mechanically substantially identical, and is illustrated in detail in Figures 3, 3, 3 and 3.

Furthermore, each dial 10, 12 or 13 may control the impression of a low frequency ringing current on the emitted wave. This is accomplished by the connections shown in Fig. 4, where the dial is arranged to control a switch 155, 157, to open the switch when the dial is ata normal position, and to close the switch to send the low frequency ringing current, when the dial is away fromthe normal position as described more in detail below. i

Referring now specifically to said Figures 3, '3, 3 and 3, the dial mechanism there illustrated comprises a flat disc 335 having ten ratchet notches cut-therein, as shown at 344, and also an additional notch with a curved bottom, 346. These notches cooperate with a pawl 313 carried by an arm 311 to which it is pivoted at 312. The arm 311 itself is pivoted at 310 toa stationary portion of the housing, 339, and is forced to the left by a spring 347 so that normally the pawl 313 is held against the periphery of the disc 335. The pawl 313 is urged downwardly by a spring 315 connected at one end to a pin 316 on thearm 311, and at its other end to the pin 314 on the pawl. A stop 317 secured to the edge of the disc 335 and movable length #9. The pawls 327 and 328, when the disc 335 is in its normal position, will pawls 327 and 328, and releasing tlierlisc 331,-

which thereupon returns to its normal position in response to the spring 332, and thus restores the entire mechanism to its normal position ready for anew call.

Referring now to Figure l, there is illustrated another form' of circuit embodying my invention. This circuit differs from that shown in Figure 1, in that it is far more sensitive, selective and powerful, these advantages being obtained by substituting crystal oscillators for the condensers in the dial of Figs. 1 and 2. and by substituting screenedthe Zero position should be insufficient, any

grid tubes for the ordinary thermionic tubes used in the Figure 1 circu1t.

- In this form of embodiment the dial is simplified electrically to include merely a single contact element 113, the outer end of Which is arranged to make contact with the stationary contacts 88 to 97 inclusive, arranged adjacent the circumference of the said dial in much the same way as the contact'25 of Figure 1 cooperates with'the dial contacts 31 of that figure. It will be understood, of course, that the stationary contacts are not all engaged by the dial contact 113 every time said contact passes'a stationary contact. but that the dial mechanism illustrated in Figs. 3, 3a, 3?) and 36- will operate as in the other modification to'cause a temporary connection with only that particular stationary contact which corresponds to the highest digit to which the dial has been turned upon each actuation thereof.

.It will also be understood that if the friction in the dial which retards its return to of the usual known retarding means may be provided to slow down the return of the dial,

in order to provide a sufiiciently long time .of connection between the said rotating and 'stationary contact, in orderthat the wave filters hereinafter described may have sutii- "wires 98 to 107 inclusive to the conductor 108, which is connected to earth by conductor 109, as shown. Another conductor 11-1- leads from the shaft 118 of the said dial to the grid of a screen grid tube. A switch icomprising lever 155 and stationary contact 157 is placed into position to cooperate mechanically with the dial 13, as illustrated. diagrammatically at 15 1. This is intended to show that by some mechanical connection between the shaft 118 and the element 15st, the switch lever 155 will be removed from the stationary contact 157 whenever the dial is at normal position, but that the said switch 155157 will be closed whenever the dial is away from its normal position, for instance, in the position shown, wherein contact 88 is connected to the movable contact 113, and

, therefore to the grid 115 of the screen grid tube. V

This switch 155, 157 controls the input circuit of a low frequency ringer 161, which comprises a source of power 158, connected to the switch contact 157 by a conductor 160, and then through movable switch element 155 and conductor 156 to the ringer, andback to the source of power through conductor 159. The output side of this ringer is connected through conductors 162 and 163 to the primary coil 164- of a transformer comprising also a core and an output winding 166.

l? fez-ring bar-l; now to the screen-grid tube which comprises grid 11.5, screen-grid-127, cathode 116 and plate 117, the grid 115 of this tube which is, as already stated, connected to the shaft 118 of the dial is also connected through conductor 121, coil 122, conductor 123, grid leak resistance 124v and con 'ductor 125 to the common ground conductor grid 127 is connected through conductor 128 to an intermediate potential point of a source of power 153, which may be a B battery or a similar high voltage power source. A condenser 120 is interposed between the oathode 116 and the conductor 128, as shown.

The plate circuit of this tube comprises a source of high voltage power 153, the negativeterminal of which is connected'to the ground conductor 108 by a conductor 152, the positive terminal of said power element 153 being connected through a coil 131and conductor 132 to the plate 117. A circuit comprising conductor 120, condenser 118 and conductor 119 forms a shunt between the grid 115 and the platc117, as illustrated. This screen-gridtube with its connected circuit, serves solely to amplify the oscillating currents conducted by the wave filters 68 to 77 inclusive, and takes no part in the functions of signaling or talking.

A microphone 173 of any desired type is connected through a conductor 172, source of power 171, conductor 170 and primary coil 169 of a transformer or induction coil, back to the microphone 173, as shown. The

said transformer or induction coil has a. core output Winding 167 is connected in series with -the output winding 166 of the signaling transformer through a conductor 177 to the negative terminal of a source of energy 140,

which furnishes a negative bias to the grid of the second thermionic tube, shown in Figure 4, to which it is connected through the conductor 148, coil 138 and conductor 134, as shown,

The grid 135 is connected to-the plate 117 of the preceding tube by means of conductor 132, condenser 133 and conductor 134., as shown. Thus, the coils 131 and 1338 together with the stopping condenser constitute what is known as an impedance coupling between the output circuit of the first screengrid tube and the grid circuit of the second tube.

The'screen grid 136 of this tube is connected by conductor 139, on the one hand, to an intermediate potential point of the high voltage power source 153 and, on the other hand, is connected through a stopping, condenser 141 to the conductor 147, which connects the cathode 143 of the said tube tothe ground conductor 108. The cathode 1430f this tube is energized by any suitable means 142. The plate 137 of the tube is connected to the positive terminal ef the high voltage source 153 through conductor146, coil and conductor 144. The coil 145 is coupled inductively to the coil 110, one terminal of which is grounded through conductor 109, and the other of which is connected to the antenna111.-

A hook-switch 176 is illustrated diagrammatically and is so arranged that when the receiver is removed from the'l'iook, the switch arm 176 will be connected with the stationary contact 175, which will close a path co1-n prising winding 166, conductor 174, switch arm 17 6 and contact 175, so as to short circuit saidi winding 166 whenever the receiver is removed from the hook. T V

The operation of the circuit shown in Figure 4 is as follows: Upon actuation of the dial to call the remote subscriber, said dial will actuate the contact 113 to close one of the crystal circuits, when the said dial is released by the finger of the subs )riber making the call. Thcreupon the corresponding wa ve filter of the-series 68 to 77, which are assumed to have different fundamental frequencies, will' conduct oscillations which will heimpressed" upon the grid 115 of the first'tube. This tube will amplify said oscillations very strongly, and in turn theamplified oscillations will ,berimpressed upon the grid 135 of the s cond tube, through the interposed impedance coupling 131, 133 and 138. This tube in turn will amplify these oscillations and impress'them upon antenna. 111 through the output coil 143, which isvcoupled to the antenna coil 110. During all this time, the low frequency ringer 161 is producing low frequency impulses near or "below the lower limit of audibility, which are impressed upon "the input Winding164 of thetransformer, whose 135 of the second tube, thereby impressing oscillations of a ringing frequency upon -said output winding 166 is connected to thegrid E grid at the same time that the wave filters condu ct their own high frequency oscillations to said grid. '1

Thus, high frequency oscillations modulated by the ringing frequency areimpressed finally upon the antenna 111 and transmitted through space to the various receiving Istations. 7 I

The low frequency rlnger 16:1 w1ll,'of

course, continue to .be'encrgize'd so long as the dial 13 is away from its normal position, and will automatically stop producing low frequency oscillations when the dial 13 re- 1 cuit the output winding 166 of the ringing I transformer, so toremove its: needless, inifpedance from the talking circuit, until such time as the receiver is again-returned to the hook and conditions are returned toreadi-ness for signaling the next'numberto be called. 7 Referring now to Figures 5 and 6, there 1s indicated diagrammatically in these figures one arrangement which the receiving station may employ. The circuit comprises an an-" tenna 182- connected to the ground through coil 181 and conductors and 178, as shown.

The energy received by the antenna is trans- ,mitted to the coil-183 by induction,="'and thence passes through conductor 184 to the grid 198 of the screen grid tube-221.

- The other terminal of the coil 183 is connectcd to the negative terminal of asource of power 185, which furnishes a negative bias to the grid 198, and-the other terminal of which is connected to thegrounrlconduo tor 178, as shown. Aby pass condenser 191 is shunted across the terminals of said source by means of the'conductors wean-d 192, which connect it respectively to the conducters 193 and 178. The cathode 197 is pro? vided with a suitable energizing means 196 and is connectedto'the'ground conductor 178 through a conductor 17 9. Thescr'ee'n grid 199 is connected through a conductor 194 to an in:

termediate point of ahigh potentialpower source 219, thenegative terminal of which I is conne'ctedt-o the ground conductor 178 through conductor 220,andthe,positiveitere minal through theW'inchngQOZof a ftr'ans-x former, and" conductor 201, to the) plate ofthe' said'tube. v

A by pass condenser 1951s connected between thercathode 197 and the conductor194 leading to the screen .grid 199, as shown. These elements constitute the input and output circuits ofthe screen-grid tube 221, the input side of'which is tuned broadly by Ineansof the coil 183 only, and this tuning 'may be made sharper by means of the condenser 186, which is connectible across the said coil 183 through conductors 187 and 190, and interposed hook switch'188, 189, which is so arranged that this switch will be closed when. the receiver is lifted from the hook. Coil 1'83 and condenser 186 are tuned so as to have a receptive range sufliciently wide to pick up any wave length to whichthe circuits associated with coils 231, 241, 251 and '261 are tuned.

202 and 204 may be arranged upon the core 203, as shown, although it will be understood that core 203 must be of a'high frequency type, that is, the lanimations must be of very thin good quality iron orsteel, and if the frequencies are sufficiently high the core may be .omitted entirely, thus constituting a transformer coupling between the plate 200 of thefirst tube 221 andjthe grid206 of the second tube 222. a

The output of the tube 222 comprises the winding 209, one terminal of. which is c011- nected through conductor 208-to the plate 207 of the said tube,'and the other terminal of which is connected through the conduc' tor 217 to the positive terminal of the source of highvoltage energy 219. c r

' Coupled to the winding 209 are a'series of windings 231 241, 251 and 261respectively, each of which supplies the input energy for; a corresponding one of a series of there mionic tubes 240, 250, 260 and 27 0. The first of these tubes 240 constitutes the amplifying means for the received 1 talking currents, While the remaining three, 250, 260 and 270, are provided for signaling purposes only. Consequently a hook switch indicated at 227,

228 is provided and so arranged that when the receiver is lifted from the hook the.circuit will be interrupted, between stationary contact227 and movable contact 228, wherebythe energy from the power source'219 arrivingthrough conductor 215 can not pass to conductor 229 when the receiver is oil the hoolnithus avoidingany needless-flow of energy through; thesignaling tubes, except.

Each coil 231, 241, 251 and 261, and their respective condensers 233, 243,253 and 263 and associated thermionic tubes form different, individually pre-tunedcircuits. The circuit associated with coil 231 is tuned to the talking wave length of this particular station and would be the same wave length as that selected by the dial 10, 12 or. 13 at the end of the dialing operation. The circuits associated with coils 241, 251 and 261 would be tuned to different Wave lengths, each the same as the wave length representing the calling wave lengths for this particular station, as determined by the dialing of the calling subscriber. station represented 'in Figs. 5 and 6is station number 357, for example, the respective circuits associated with coils 241, 251 and 261 will be tuned, respectively to the Wave lengths sent from circuits established through contact points 3, 5 and 7 by the dial at the sending station.

The tube 240 which amplifies the conversation currents is connected to the output winding 231, which is connected to the cathode 237 through conductor 239 and'to the grid 235 through the grid condenser 234, and grid leak 232, as shown, a'tuning condenser 233 being connected in parallel with the coil 231. The cathode 237 of this tube is onergized by suitable means 238. The receiver 224 is connected as usual in a circuit comprising the conductor 215, leading from the positive terminal of the source 219 and passing from the receiver 224 to the plate 236 through the conductor 225.

The. signal operating tubes 250, 260 and 270 are coupled to the winding 209 in a manner similar to that of tube 240, each tube having a corresponding winding 241, 251 and That is to say, if the 261, connected to itsrcspective grid 245, 255,

265, through the grid condensers 244, 254 and 264, each grid condenser being shunted by a corresponding grid leak 242, 25 2, 262, and each] winding 241, 251 and 261 being shunted by a tuning condenser 24.3, 253, 263 rcspectively, and being connected to the cathode 247, 257 and 267 through conductors 249, 259 and 269 respectively. Each cathode is actuated through a suitable source 243, 258 and 268. The plate 246 is connected to the positive terminal of the source 219 through a conductor 271, in which is interposed a vibration relay V thence through a 0011d11 ttor 229, through the hook switch 228, 227 and conductors 226 and 215 to the said positive-terminal of source 219. Similarly the plate voltage, is supplied to plates 256' and 266 through conductors 272, 273 and 274, 27 5, wherein are interposed the corresponding vibration relays V and V,,, respectively,

The vibration relays and their circuits are illustrated in Figure 6, although it willbe understood that Figure 6 really forms apart ,l1ere,-other than the ststenr 'eral a reed is set into vihr:

siderflhle or V,

. the 'ontucts thence throng 1 type, wherein a contact is established only 'when current of the proper t supplied thereto. Such relays are W in the art and need no further description t that in genron by the field produced by an alternatingor pulsating current in u coil and this vibration becomes conwhen the requency otfthe current near the natural frequency of vibretionotf the reed.

The relay V controls ercircu conmrisingr conduc'lor 27S, source of en 'y tor 280,clectromsgnct a r this circuit being cmurocted to 276 and 277 or" thou-clam so t incgrnes'; 281 hecoznes c ner, cont-nets are actuated. ll hen V net 281 heroines energized it will armature and cause itto e W contact 283. A dash not retard the return motion at the s The relay V iseriuctly lil-te the and inturnmmtrols a circuit corms-rising conductor 282. miniature cert tor 28-1 clectromsgnet 3 the 9292', conllru'tor 290,

to the conflicts r a conductor source of" energy 291, and this circuit being connected 288 and 289 controlled by the lay V I 11 srmutru'e ro erstes withlhe'eler tromegnet 293 and is retarded by :1 dash notiT. these pa s heinp; similar to the corresponding p: fl'S sud of the first rc luv. hen the clectrmnnc'net 293 is encr-' sized by current flowing: from the source 291, and when the relay V5 is closes and simultaneously relay armature is with 283. the zirnmture v-J bv eleci'romsgnet and tlu i V be ceiniccted with said will establish :znel'herri ductor 29:), electroum 3GP smlrce of energy 2-302, ceud' 360 and oi 'l conflu mature 295. it, th nected to the srmstu L cusl r the rclay'V; be c which is connected tothe eonductcrs 30?, 308 will be closed and the signal oi? the called subscriber (not shown) will be actuated for a period depending upon the charac eristics conduc-Q 1 curing of the erinsture 305. v I

flhe operstlon of the c1rcu1-ts shown 1n Figures 5 and 6 is as follows: I

l Vhcn an impulse of radio fr q with" in a certain range of Wave lengths, strikes the antenna 182, the resulting currents proof the dash oot306, which retards the mot-ion 'duced in coill83 Will be amplified at radio frequency, first by the screen-grid tube 221,

turn to the ourseparatewindings 231, 241,;

and 261, connected to the respective tubes 2&0, 250, 260, 270. Each of these'tubes as described has s detector circuit attached to the grid thereof, wnereby' the radio frequency impulses ZUYG-COHVGTtGd intoiuldio frequency impulses in the corresponding platecircuits.

As stated in the description of Figure 4, the period that the dial is bcmg opereted, ringing currents of low frequency are superimposed upon the high frequency impulses emitted by the transmitting antennu and thesehigh frequency currents thus modulated are impressed simultaneously and successively on coils 241, 251 and 261, as dcterlnincd by the dialing. The successive calling wavelengths are each di'lterent, and

they are such the respective wave lengths to which the circuits associated With 241, 251

or 261cm tuned, and are sent in properse ({HQIICC, the bell will be rung at the station" 1 7 v wv shown in Fig. l he final wavelength1mgiresscd on tl'ris station is the Wave length filor this station and is that to which 231,

2 33 and 220 are tuned. In the; circuits of the tubes 250, 260, and 270, they will 'trzwerse the vibratory relays V V V and if the input circuit of any one of these tubes is tuned in reson sncc with the high frequency impulses received the magnitude of the received curre cultu cluste the vibrutory releyi f the impulse be of such frequency that rclsy'V or actuated without actuating IV however no siq'n'alin will result for r tJ b 3 although the contuctsof relay V or V3 might (llGSQ-XlySElll they would not complete 011'- cui which include the electromagnets 293 or L03 inasmuch as the circuit ofthe, first relay iso'pened between'285 and 283. There'- fore, it is essential that-the relay V be the 5 to operate, it the signaling'means is to actuated. This requires that the first impulsesent outmust be of the frequencyto x'vhleh the tube 250 istuned, in order that suiiicient power may be fed to relay Vy to bi contacts together. W hen this conit will be sutlicientin that purticulercirurtion has been established the clectroniagnet28l will be actuated, and this in turn will close the contact rat'283ywhich will remain closed after the encrgiza'tion of 281 ceases for such period as the dash pot 286 is adjusted.

that in turn it will cause the electromagnet 293 to be energized during the remainder of l the period before the armature 2 85 breaks connection at 283. 1

.. Finally, if a third "impulse be received by the antenna 182, and likewise this be of a frequency for which the circuit or tube 270 is tuned, the last electromagnet 303 will be energized in a similarway, and it in turn will close .the ringing circuit and the bell of the subscriber being called will rin WVhen he lifts up his receiver 22%, he will automatically breals the signaling circuit,

and thus disconnect the three signaling tubes from the circuit, and likewise he will throw the condenser 186 across the input coil 183, thus sharpening the tuning very considerably and concentrating all the talking energy into thereceiver circuit, namely, the circuit controlled bytube 2 10. V v

lVhile for simplicity and convenience of illustration two different receiver hooks 189 and 228 have been shown, it will be understood that these are merely diagrammatic showings, and that both, in fact, are merely switches which are controlled by a single hook, namely, of one upon which the receiver 224 is supportedwhen not in use. It will also be obvious fronrthe circuits shown, that unless impulses of the proper frequency are fed in proper sequence, and

. within predetermined limited times, to the three relays V V and V no signal will be produced, although one or more or even all of therelays may be actuated in improper sequence.

These frequencies are, of course, determined by the dials 10, 12 or 13, as. the case may be. It will also be understood that while only three relays of the types-V V V are illustrated, it is possibletouse any desired number, dependent upon the number of digits in the largest telephone number to be called.

It is also obvious, of course, thatif greater power be required at the transmitting end, or greater sensitivity at the receiving end, this may readily be provided by correspondingly increasing the number of thermionic tubes employed.

A further feature of the system employed in accordance with this invention is that the tube 240, over which the actual talking is done, has its input circuit tuned to a frequency corresponding to the last digit of the number obtained by adding all the digits of the called subscribers own telephone number.

For example, if his number were 153, the sum of the digits would be 9 and thelast figure of dial 10 has been moved in that case. and this produces radio frequency currents of that frequency whenever the hook switch 28 has risen into contact with the stationary contact 27. Therefore, the calling subscriber auto matically. tunes his transmitting station to the frequency for which the receiving station he is calling has been adjusted. Thisis accomplished as is shown diagrammatically in Figure 1, and as shown more in detail in Figure, 80.

It must be understood, of course, that the various circuitsand instrumentalities illustrated are purely diagrammatic in nature, andthat in practice necessarily refinements and details will need to beconsidered which form no. part of the invention itself, but are in accordance with ordinary telephone and radio practice.

It will also be understood that many deviations fromthe structures and circuits illustrated will occur in practice without departing from the spirit of the invention, which is defined by the following claims.

\Vhat I claim as my invention is:

1. A system of radio telephonic communication comprising a series of subscribers stations, each having calling means including a manually operated dial capable of emitting a sequence of impulses of certain fixed wave lengths, and in an order determined by the movements of the dial, the movements of the dial also simultaneously establishing a frequency. on which conversation can be carried on, and a receiving-circuit which isresponsive, at each station, only to a particular one of such sequences, whereby the signal of only that subscriber who is called will be operated.

2. A system of radio telephonic communication comprising a series of subscribers stato the same frequency as that established by the movements of the dial at the sending stathis sum would therefore also be 9, or if tion.

3. A system of radio telephonic communilength for ringing, and in an orderdeter v mined by the movements of the dial, the movements of the dial alsosimultaneously establishing a frequency on which conversation can be carriedon, and a receiving. circuit which is responsive, at each station, onlyto a particular one of such sequences, whereby the signal ofvonly that subscriber who is called will be operated. A g

4. A dial for use in radiotelephony, comcooperating with said dial, whereby upon partial rotation and return of said dial, only one of the contacts is caused'to control a corresponding circuit, and other means co,- operating with the dial, comprising a ratchet wheel, a pawl pivoted to the dial and engaging the teeth of said ratchet-wheel, and a.sec ond pawl to prevent the ratchet wheel from returning when the dial returns to its normal position.

5. A dial for use in radio telephony, comprising a plurality of contacts, and means cooperating with said dial, whereby upon partial rotation and return of said dial, only one of the contacts iscaused to control a corresponding circuit, and other means cooperating with the dial, comprising a ratchet wheel, a pawl pivoted toth'e dial and engaging the teeth of said ratchet wheel, and a second pawl to'prevent the ratchet wheel from returning when the dial returns to its normal position, whereby'the ratchet wheel is moved to an extent equal'to the sum of the successive movements of the dial. V

6. In a radio telephone having a"tra ns mitting circuit, a dial having a plurality of contacts. a receiver hook, a switch'actuated thereby for controlling the transmitter cir cuit, and means cooperating with said dial, whereby upon partial rotation and return of said diahonly one of the contacts is caused to control a corresponding circuit, and other means cooperating with the dial, comprising a ratchet ,wheel. a pawl pivoted to the dial and engaging the teeth of said ratchet wheel, and a. second pawl to prevent the ratchet wheel from returning whenthe dial returns to its normal position, and means connected to and actuated bythe receiver hook ,for releasing both pawls when the receiver is returned to the hook, whereby the ratchet wheel will be capable of returning 'to its initial position. r

7. In a radio telephone having a transmitting circuit, a dial having a plurality of contacts, a receiver hook, a switch actuated thereby for controlling the transmitter circuit and means cooperating with said dial, whereby upon partial rotation andfreturn of said dial, only one of the contactsfislcaused to control a corresponding circuit, and other means cooperating withthe dial, compris ing a ratchet wheel, a pawl pivoted to the dial and engaging the teeth of said ratchet wheel,

and a second pawl to, prevent the ratchet wheel from returning when the dial returns to its normalposition, and meanscon'nected to and actuated by the receiver hookfor ref leasing bothlpawls when the receiver is returned to the" hook wherebythe ratchet wheel will vbe capahleof returning'toits 'initial position, and a spring for returningjthje said ratchet wheelto itsrsaid initial position. prising a plurality of contacts, and means 8 A for, use in radio-tclcphonypcomprising .a disc having a series of notches therein, constituting ratchet teeth, Land; a

superposed ratchet wheel, aIpawl cooperat ing with the disc to, be actuated ioneof f the teeththereof, contact controlling means actuated by said pawhand asecond pawl pivoted to thedisc and cooperating: with the ratchet wheel, and a thirdpawl also'cooperating with thesaid ratchetwheel-to retainit the second pawl.

in the position towhich it has been moved loy 9. 'A dial'for use in radio telephony, foo mtherein, constituting ratchet teeth Qanda superposed ratchet wheel, a pawl 'cooper ating with the disc .to begactuated one of the teeth thereof, .contactcontrolling: means actuated by saidpawl, and a-secondgpawl :pivtit-Q oted to the disc cooperating;withf the saidsecond and third paivls for engagement with the ratchet wheel.

7 10. AV-dial foruse inradio comprising a disc, a ratchet wheel cooperating therewith, means whereby v disc shifts the ratchet wheel, a shaft .ci0ni1ected to the ratchet wheel, a doublearmedcontactglever operatedbysaid shaft rand a series ofustationary contacts cooperating; with th e ,said contact lever. r a

. 11. A dial for use in. radio telephony-seemprising a disc, aratchet wheel cooperating therewith, means wherebythe disc. shifts the ratchet :wheel, a shaft. connected to the ratchet wheel, a double armed contact lever;

operated byrsaid. shaft, series ofsta- 1 tionary Icontacts cooperating with the said contact lever, saidcontacts being so atranged that one end of the lever'will always 7 engage one of said contacts, 1 v a. 12. A system of radio telephone communication comprlsing a series of subscribers, stations, each station including manuallyfcom trolled transmitting means for send ng 1111-,

pulses of predetermined frequencies in a prising a-dischaving a,series of notches given sequence at the will of the subscriber, and receiving means, the receiving .means comprisinga plurality of circuits tuned synchronously with the'transniitted frequencies, and further comprising a pluralityof interlocking relays which are operated when waves of predetermined length are received in a predetermined sequence, the transmit-.

ting means being tunable,funder the control of the subscriber, so'that it maybe caused to correspond to the wave length ofthe station with which communication is to be established, said tuning being accomplished by the manual operation of the transmitting means.

13. A system of radio telephonic commu 'nication comprising a series of. subscribers stations, each having calling means capable of emitting a sequence if impulses of certain fixed wave lengths, and in an order determined by the calling subscriber, and a receiving circuit which is responsive, at each station, only to a particular one of such sequences, whereby the signal of onlythat subscriber who is called will be operated, the receiver circuit being permanently tuned to one of a series of wave lengths, the designatingordinal of which is equal to the last digit of the number representing the sum of the digits of the telephone number assigned to the reciving station.

14. A system of radio communication,

comprising a series of subscribers stations,

each station including transmitting meansand receiving means,'the receiving means of each station being arranged to respond'o-nly to certain wave lengths sent in a particul'ar sequence, the sendingmeans of; each station comprising means for sending in succession a series of wave lengths in a particular sequence, the sending station further comprisprising means for sending as the final wave of the series, a talking or carrier wave of a tion, as determined by thesequence of successive waves sent by particularly tuned.

15. A system of radio communication, comlar sequence, for establishing vcommunication with, and actuating a signal at, only the station of a particular subscriber, the send mg station further comprlslng means for sending as the final wave of the series, a talking or carrier wave of a wave length to which a certain receiving station, as determined by 'the sequence of successive waves sent by the sending station, is particularly tuned.

thesending station, is

comprising a plurality of sending circuits I tuned to different wave lengths, and means, selectively and manually operated, for controlling the operation of saidsendingbir uits, for sending a series of waves having wave lengths, and in a sequence, as determined by the movementsof said manually operated means. j

17. A system of radio communication,

comprising a series of subscribers stations wlthm'operat ve range'of one another, each station including transmitting means and receiving means, the receiving means of each station being arranged to cut in that station for operative communication only in response to a definite'series of wave lengths sent in a definite sequence, the sending means at each station comprising'a plurality of sending circuits tuned to difi'erent wave lengths, and manually operated meansfor'controlling said sendingcircuits, for sending a series of waves, having the desired wave lengths, in the desired sequence.

18. A-syster'n ofradio communication, compr1s1ng a series of subscribers stations within operative range of one another, each station mcluding transmitting'means and recelving means, the receiving means'of each station being arranged to cut in that station for operative communic'ation only in I response to a definite series of'wave lengths sent in a definite sequence, thesending means at each station comprising a plurality of sending circuits tuned to different wave v I lengths and a manually controlled dial for wave length to which a certam receiving sta- 1 controlling the sending circuits, for sending,

inthe desired sequence, a series of waves of the desired wave lengths;:- V

Y 19. In a radio telephone, switch means for closing a' plurality of circuits in succession, a tuning device-in each of said circuits controlled by said switch means, a dial, selectively and manually operated and operatively connected with the switch means, for closing the several circuits controlled by said switch means in a sequence dependent upon the operation of. the dial, and transmitting means cooperating witheach of the tuning circuits, whereby a particular succession of radio waves is-sent by saidtransmitting means, as determined bythe movements of the dial and its associated switch means.

20. In a radio telephone, switch means for closing a plurality of circuits insuccession, a tuning device in each of said circuits controlled by said switch means, a dial, selec tuning circuits, and with the ringing signal circuit, whereby a particular successlon of radio waves, followed by a ringingsignal, is

sent by said transmitting means, as determined by the movements of the dial and its associated switch means.

In testimony whereof I alfix my signature.

HERBERT S. POLIN.

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