US2475675A - Radio switching system - Google Patents

Description

E. S. PETERSON RADIO SWITCHING SYSTEM July 12, 1949.

Filed May 27, 1946 5 Sheets-Sheet 1 July 12, 1949.

E. S. PETERSON- RADIO SWITCHING SYSTEM 5 Sheets-Sheet 2 Filed May 27, 194eA EDWARD SL PETERSONy MM ATTORNEY July 12, 1949. E. s. PETRSON f 2,475,675

RADIO SWITCHING SYSTEM A 5 Sheets-Sheet 5 Filed May 27, 1946 THAN SMITTER INVENTOR. EowARn s. PETERSON l ATTORNEY 4July 12, 1949. E. s. ETERsoN 2,475,675

RADIO SWITCHING SYSTEMV Filed May 27, 1946 y A 5 Sheets-Sheet 4 D di i l m w w p di Gi 'fw n rl a 4 Mg' 4 INVENToR. E lo H EDWARD s. PETERSON d) o BY :i l Z. Qu ,n v Y A A rToRNEY July 12, 1949.

E. S. PETERSQN RADIO SWITCHING SYSTEM Filed May 27, 1946 INVENTOR. EDWARD S. PETERSON ATTORNEY Patented `Iuly 12, 1949 RADIO SWITCHING SYSTEM Edward S. Peterson, Elmwood Park, Ill., assignor to Automatic Electric Laboratories,

Inc., Chicago, Ill., a corporation of Delaware Application May 27, 1946, Serial No. ,672,677

(Cl. Z50-6) 18 Claims.

The present invention relates to remote control or remote switching systems, and particularly, to such a system used for the control of a plurality of radio transmitters and receivers from a number of control stations. A telephone handset and dial are provided at each control point, and the radio transmitters and receivers are coupled together in pairs or units, with a transmitter and a receiver in each unit. These radio transmitters and receivers would ordinarily, in the application envisaged, be located at some central point, together with the switching equipment and one or more attendants as required.

The main object of my invention is the provision of a flexible system of control whereby any one of a large number of such transmitter-receiver units may be selected from any control station, connected to the telephone of such station for two way communication, and adjusted remotely to the desired wave length or frequency channel.

Another object of the invention is to provide the attendant or attendants with similar means of control, but incorporating special facilities not available to the regular control stations.

Still another object of the invention is the provision of intercommunication service between the control and attendant stations, and, if desired, connections with an automatic telephone switchboard.

One feature of the invention is the division of the radio transmitter-receiver units into two groups, with the units of one group controllable from the regular control stations through the wipers of a dial controlled stepping switch, while the units of the second group, whose frequencies are set in advance, are selected by means of quick select relays in the stepping switch, operated direct from a multi-point contact switch at the control station, which is set by hand to select the unit desired.

Another feature of the invention is the use of a separate dial-controlled stepping switch for each control station and each attendant station, with the radio units of both groups connected to the banks of all stepping switches, but the units of the second group made artificially busy in the banks of the control station stepping switches.

A further feature of the invention is the use of special arrangements in the attendant station stepping switches whereby the units of either group can be seized and operated by the attendant station even if already in use.

Another feature of the invention is the employment of a quick means of cross connection of units, as by means of patch cords, whereby any unit can be transferred from one group to another by a simple operation.

Other objects and features of the invention will be apparent from the description to follow and the accompanying drawings which illustrate one form of the said invention. 1t will be of course understood that numerous modifications may be made in the arrangement shown without departing from the spirit and scope of the invention.

With reference to the drawings, Figure 1 shows a portion of a control station and a :portion of the associated stepping switch. Figure 2, which goes to the right of Figure 1, shows a number of control relays and patching jacks normally associated with a given transmitter-receiver unit, and Figure 3 which goes to the right of Figure 2, shows a part of the frequency selecting equipment required for each unit. The radio equipment proper has not been shown, since its exact form is not material to the invention. Figure 4, which goes below Figure 1, shows another portion of the control station equipment and another part of the associated stepping switch. Figure 5, which goes to the right of Figure 4, shows the equipment at the attendant station for handling incoming calls to the attendant, together with an alternative impulse receiving arrangement for the frequency selecting equipment of the radio units.

In connection with Figure 1, the control station equipment is shown at the left, behind the broken line 40, and comprises a telephone, a dial |1`, and a telegraph keying jack I8 for sending Morse code if desired. The telephone is preferably of the handset type, with a press-to-talk button l0 in the handle and a side-tone circuit so the speaker can hear the sound of his own voice and thus know his instrument is working. A loudspeaker, not shown, is also indicated as being connected to this telephone, through back contacts of the press-to-talk switch.

The stepping switch is a two motion switch having vertical and rotary movements, such as commonly employed in automatic telephone systems. The vertical magnet |21 may be seen in the lower central part of Figure 1, the rotary magnet |32 at the lower right and the release magnet |04 at the lower left. A talking circuit is shown in the upper part of Figure 1 and the wipers and bank contacts at the extreme right. Eleven relays are also shown in this iigure, including a pulsing relay |00, a release relay |05, a vertical transfer relay H0, a battery feed line relay H5, a busy relay |20, a differential line relay |30, a switching relay |40, rotary transfer Yper-mitsseveral.controlstations making up asing1e-radio-unit.

.other and .in vshunt relays iii-8 and |55, a cut-oli1 relay IE, and a rotary interrupter relay |65. The attendant station has a switch similar to that used for control stations, except for a special over-ride conductor H8, and special connections to the pulsing and test bank contacts 'such as indicated at lQZA, 594A and I97A. It may or may not be provided with quick select equipment.

In Figure 2, the talking circuit and the four control relays normally associated vWith a particular receiver-transmitter unit are shown connected to a particular set o'bankcon'tacts in the switch. This talking circuit and the various other circuits controlled by these relays .are connected to the associated radio :unit through `the patching jacks shown on the right f the relays. By plugging patching cords into these -jacks in case of trouble for example, the normally associated unitvcan be quicklyfdisconnected and a different unitlconnected upiin its place, the

various jack contacts beingopened.upon the insertion #of the plugs -of the ypatching .cord `into the jacks, and the circuits connected straight through. At thelower lleftof lligure Z-is indicatedlanother set-of patching jacks forV connecting the .requirediradic units tothe quick select circuits i'ci the stepping switches. The talking circuit of eachzunitfismultipled to several jacks intheupperirow, while the quick select circuits of the different Astepping switches are connected individually tothe `jacks of thelower row. This to come y inzonthe .same -unit over vthispath .at the same time. When a patchvcord .suches 2M is .plugged .into an upper jacksuch .as 2!:5,=a:busy.lamp such as 21.3 is'lightedand busying relay 2in isoperated. Theother control relays .are alcutoi lrelay .220, a hold relay 230,-.andatalk-list-en relayM.

In .Figure|3, the rectangles A3H! and 353 represent a radio receiver land a radio transmitter .Identical channel selecting circuits, Jcomprising .four .relays and a .ten point automatic telephone practice'as a minor switch, are indicatedinfschematic form. in. each rectangle. Relays .3!0 land-350mg pulsing relays, relays .320 and Btl? are .wiper .guarding relays, relays 330, 340, 310 and -380 ,are pulse .absorbingrelays yand the minor switches are lindicated under the brackets 3.15 and i355. going .to .the receiverfrom `.the switching: and` control equipment, namelyrsafpairof incoming speech leads 395i and .30! terminating in the :receiver output transformers I 4, apulsing'conductor 362, and .a locking conductor 3523, -which 'is required only when the channels'to befselected'exceed ten. Similarly, six leads 2go to the transmitter from the switching andcontrolfequipment: a pair of .outgoing speech leads terminating inthetrans mitter input .transformer {354,fa locking conductor 3116, afpulsingfconductor 307, atel-egraph conductor 308 which goes to yarkeying relay, anda switch talk conductor 399 whose 'function is to prepare the transmitter .to handlerspeech. The radio circuits themselves .are not shown, since they formno part of theinvention.

In Figure 4, :the control station quick-select hand switch `is `shown `at the left, behind the broken line 50. .Each of .the two contact arms of thisswitch is .connected .to a pair of ycorrnbination .relays 4B!! and 4H), .and 42Uand 43.0, the relays oi each, pair being Wired in. series with each with oppositely poled dry disc rectiers. The other side of each pair of relays is taken to a grounded source of alternating cur- .Four leads "are :shown l stepping Iswitch 'commonly known in rent such as the transformer 439. The contacts of the quick select switch are connected to direct ground, to ground through a dry disc rectifier such as poled to pass positive half cycles of current, to ground through a dry disc rectifier such as '26 poled to pass negativ-e half cycles of current, or are simply left open. Thus, for different settings of the contact arms, which are arranged to move together as a unit, the relays tilt to 36 and their dependent or slave relays 445 to 485 are operated in diierent combinations to make the required selection. Direct ground on a contact arm, for example, will cause alterhating current to pass through the relays of the associated pair of relays, causing them both to operate, whereas an absence of ground will cause neither to operate. Positive half cycles of current on the other hand,'through rectier disc 25, will cause the first relay of .theassociatedpair tooperate, andfnegative half cycles through rectier disc l255 -will-cause the second relay only, to operate, by the bucking and shunting eiect of the discs associatedtherewith.

A total of yfifteen .relay combinations and fteenselectionsare made possible with therequipment indicated. It will ybe .apparent however, that by vthe use of additional pairsof relays and agangswitch with more=contact .arms and more contacts, or by using a bank .of keys or push buttons instead cfa -contactswitcm this number could be increased materially. rIhe complete list of .combinations Aused herein is shown inthe following .table Switch Relays Position Operated 1 4to, 410, 420,430 2 400, 415, A42d 3. 455, All), 431i -4 dill), 'M0 40 5 aco, l42o, 4to 6 400,42@ '7 lttl), 430 8 "40B `9 lllllfll'ii, 430) .1,0 i i als, :c2c r1. 43B

. 42e, ist

it is assumed VIn Figure 5, the equipment at the left is the intercommunioating equipment required at the attendant station. The upper portion is for calls made through the banks of thestepping switches, and the lowerportion for calls made by Way of the quickselect relays. Separate repeating coils 565 and`508 are employed, together with separate . signal buzzers 512 and 552, separate signal lamps 51.3 and "553, and separate battery feed relays 5m and 550. The attendants telephone, .not shown, may be connected to either circuit through the answering key 54. This could be the same phone used by the attendant for radio calls, .but here to be a separate instrument. In the case of several attendant stations, a quick select circuit could sbe assigned to each, thus reducing the number of circuits available for radio selections overthis path, or a single quick select circuit could be madeavailable for calling the head attendant, with the other attendant stations accessible only through-the banks of the stepping switch.

On the right hand side of Figure 5 is shown the alternative pulse receiving arrangement already entioned, for controlling the channel selecting luipment of the radio units. In case it is dered to release the channel setting minor vitches at the end of each call, upon release of 1e connection, a circuit such as this is necessary. :i the channel select circuit of Figure 3, the iinor switches remain in the last operated posilon until the next call, when they release at the tart of the channel selecting operation, as will e explained. In Figure 5, relays 520 and 560 1.,

of the receiver. Both types of channel selecting y circuits may be used if desired, in the same installation,

Control station call to first group In the operation of the system, an operator at a control station, to initiate a radio call through a radio unit of the rst group, removes the handset from the telephone, thereby causing the cradle -switch IG to close its contacts. This causes pulsing relay lilo to operate from ground at the cradle switch, by way of the dial impulse springs I9, and conductor 32. Relay |00 upon operating, closes make contacts and |82, but without effect at the moment, and at make contacts |03 closes an obvious circuit to release relay |05 which operates. Release relay H15 upon operating, closes make contacts |05 and |51, but without immediate effect; at break contacts |01 disconnects ground from the release circuit now open at vertical off normal springs H4; at make contacts m9 prepares a local pulsing circuit; and at make contacts |58 closes a circuit to the lower winding of vertical transfer relay HD, by way of the normally closed vertical off-normal springs ||1.

Transfer relay ||0 upon operating, at make contacts ||3 prepares the Vertical magnet stepping circuit and at make contacts ||2 connects starting ground to the tone start conductor H3 which leads to a dial-and-busy-tone unit, not e.,

shown, such as commonly used in small auto-- matic telephone exchanges. This tone unit, which may be nothing more than a buzzer relay and a pair of interrupter relays, along with a transformer or a choke coil, thereupon starts and connects a steady tone to the dial-tone conductor its whence it passes through the closed break contacts itil and the closed make contacts to the talking conductor 3|, through the receiver i4 and condenser l5 of the calling telephone, and back over talking conductor 35 to grounded battery through the upper winding of relay H5. This tone serves as notice to the calling station that the equipment is ready for dialing. Interrupted tone is also connected to the busy tone conductor |23 by the tone unit at this time, but this is without effect, due to the open make contacts i2! on the busy relay.

The operator at `the control station, upon hearing the dial tone, operates the dial twice to select the desired radio transmitter-receiver unit. On the rst pull of the dial, as soon as the dial moves off normal, the shunt springs, which are the upper three springs on the dial, close and connect ground to both of the talking or line conductors 3|] and 3|. The ground on the lower conductor 3| shunts the lower windings of relays ||5 and itil, while the ground on the upper conductor energizes the upper windings of these relays, and causes them to operate in series. Both of these relays operate and close their make contacts ||6 and im, but without effect at this time.

The dial Il upon. being released, returns to normal and at its impulse springs |9 interrupts the circuit of the operated pulsing relay mi] the required number of times, depending on the digit dialed. rlhe pulsing relay Ille' follows these dial purses and reverses the position of its contacts a corresponding :number of times. Contacts itl and |02 are still without effect, due to the open make contacts Mft and |55 on the switching relay. Break contacts tilt of relay Hill, however, repeat the dial pulses by way of make contacts |09 and H3 to the vertical magnet |2'l and the upper winding of relay lie which are now connected in parallel. The vertical magnet operates intermittently in response and at each operation raises the switch shaft and wipers one step until they are opposite the desired level of bank contacts.

g At the first step, the vertical off normal springs lil shift position and open the operate circuit to the lower winding of relay Ht which is now held through its upper winding. The circuits of relays m5 and II@ are opened and closed intermittently during the pulsing, but these relays remain operated during these momentary interruptions, due to having been made slow to release by the use of copper sleeves over their core.

When the dial reaches its normal position a again, the dial shunt springs open, and release relays M5 and |30, and the impulse springs close and remain closed, thereby holding relay wil. Transferrelay iii) after a short delay now releases, and at break-make contacts H3 disconnects the now open pulsing circuit from the vertical magnet |2l and connects it to the rotary magnet |32. Relay H5 also at make contacts iii disconnects the dial tone from the line and at make contacts H2 removes ground from the tone 'I start conductor, whereupon the tone equipment will stop operating, provided of course that the tone start lead is not grounded at this time from some other switch.

Upon the second operation of the dial, the movement of the dial off normal again closes the shunt springs, which again causes relays ||5 and |36 to operate in series over their upper windings. Upon the release of the dial, impulse springs I5 again interrupt the circuit of relay ltlii intermittently, and this relay follows the pulses as before. Upon the first release of relay It@ at the start of the second series of impulses, a circuit is closed to the rotary magnet |32 as follows: ground at break contacts E53, make contacts m9, break contacts H3, break contacts |25, |58

and |51, and the winding of magnet 32 to negative battery. A branch of this circuit also passes through the winding of rotary transfer relayv Hill. Relay l'il and the rotary magnet thereupon both operate. Relay |56, at break contacts I5! ydisables the circuit of the interruptor relay |65, at make contacts |52 closes a shunt around break contacts |25 and |53 to prevent interference with the pulsing by the busy and switching relays, and at make contacts |55 closes an obvious circuit to rotary transfer relay |55, which also operates.

Transfer relay |55 upon operating closes make springs E55, but without effect, and at breakmake contacts |57 momentarily disables the operate circuit of the switching relay |40 and pre- 7* pares; ai. circuit: for.' theI busy.' relay. |20.v The rotary, magnet nowfcperates intermittently in response-tof the pulses, and at each operation rot'at'esl theV wipers intoy the'.A selected level in the switch bankl untill the bank' contacts of the selectediradioiunitgsucn asthe contacts |80 etc. shown in Figure. 1i arereached. Transfer relay |50 remains operated during thepulse interruptions, since it* alsoismade` slow toreleasefthrough the useaof a` coppensleeve overthe core.;

At the' end: off the: second. digit, pulsing relay remains'icperated as before, and relays H51 and |30againzreleasewithout effect. Transfer relay |501 also releases'. after a short delay, and opens the circuit of transfenrelay |55 which also releases, after'a; stilhfurtlierfshort delay, since it alsoisimadefslow to release.

Assuming.thattthefcalled-unit is not in use, and is not otherwise made busy, test contact ld in the switch bank will have negative` battery on it, throughitheupper: winding or` the hold relay 230. Upon'. the release. of rotaryv transfer relay |55 therefhrthe: closing'.- off` break. contacts |51 completeszra. circuitf for the opera ion ofswitching relay. |4-0sfin'fserie's witlirelay230fasfollows: ground atimakeicontacts L06', break. contacts |23, upper winding. off relay |40', break contacts |57', test' wiper |93, testicontactiA |94; conductor 203, busyingkey 236breakc: contacts 2| l, and: the upper windings?ofrrelayf230ftbbattery. Relay 230 upon operating. extends groundr from 23z|f andi. 232-t'through,x the patching jacks to the hold conductors 3.03.7 and:- 3il6r.` Relay |40 upon operating. at: make. contacts lfl'l:l locks to ground atzmakefc'ontactsf |07, and at break contacts Ifl disables the; pulsing circuit to rotary magnet 32. Switching-5relay. I li0-also at, make contacts |4| and |4'2eX-tendszthe:talkingcircuit fromthe calling control station to thereceiver of the selected radio unit Thisl circuit. is: fromv the line conductors 30 and-.31, throughA the repeating coil |38', make: contacts; |4^| and |42; break contacts |l6f| and |62, switch wipers |8`| and |89;` bank contacts:` |88; and. |9|) conductors 200 and 20|, througlfiv the?v repeatingy coi1= 235, break contacts 2M? and 242;. the upper.' patching jacks,` and conductors. 300s and. 3.0

contacts: |43? disconnects thef busy tone circuit, at'. makef contacts.` for theunit pulsing. relays,3|0 and` 350, andat makezcontacts: mit connects direct ground to the test` wiper' |03, toymakethe called unit busy to the'r other. control stations.

Theioperator: atthe calling control station now dials the third orH channel: selectingy digit. When thef dial1 movesoif normal; relays H5 and l30 again operate (inlseries over. their upper windings as before. 'Ilhis time; the'operation of relay IIS is still.' withouts immediatey effect, but relay i3d'. uponj operating'closes: separate pulsing circuits tolrelaysf 31B? and 350'.' The circuit tov relay 3H) is from: ground at' make contacts` |3I, through make'contactsiE; makecontacts |45, wiper lill, bank'r contact |"9.-2 conductor 2022 break contacts 22|, second: patchingf jack, conductor 302, and the-winding'offrelay 3l0rtofbattery. The circuit for relay" 'llfisffromthe same ground' at make contacts liltthroughmake'contacts l0! andlM, contacts of the normal post springs |49, Wiper' |95; bank" contacts |01; conductor 2%-, break contactsv 222,. fourth er bottom patching jack, conductor. 30.7; and'thewinding of relay 350 tofbattery.. RelaysBl-O- and-350 both operate over these circuits; andaatrmakefcontacts 3H and 35| make contacts` to: the output transformerv 3M in the receiver 3|3. Relay |40 also, at breakk |544l and" |45; prepares circuits at break contacts 8f; close obvious` circuits to the release relaysl 32 and iijwhich also operate and cause the chann selecting switches to-release from their last op erated` position. The release circuits are fror the ground. at' the makeA contacts 325 and 36| through. break contacts 34% and 382, and' th closed off-normalA springs of each switch tothl respectivefrelease. magnets. Upon the closure 0; these circuits, both minor switches release im'- mediately, andfupon complete restoration to normal, open: their offenormal springs.

When the. dial is let go, pulsing relay m0 ir. Figure. 1 followsthe interruptions of the impulse springs exactly: as-before, but with different results. The: pulsing springs |03 of this relay, for example, are now without eiect, since the local.. pulsing circuit to the vertical magnet centactsi.v Pulsingsprings ||J| and ever, areznow fully effective, and at each.y interruption open the circuits of ,the energized pulsing.

if) and 350 therefore, at thefendof the.y rst impulse, ground through make contacts 3| and 35| in addition tore-energizing relays 320 and 360 which being slow to release; re

3l!! to the'upperwindings of relays 34M) and 389i Theserelays upon operating, at' to the grounds which operate. makecontactsk 342'. and 382 lock at make contactslazland` Sti, and at make conn tactsI Mi azid` 38+ prepare the circuits of the ing contacts litt andv |02 isll. anclfil'.- Relays 3M]L and 350 thereupon release, and at break'. make contacts 3H and 35| open thecircuit of release relays 320 and 360, and closecircuits tothe rotary magnets by way ofclosedfmake' contacts 34| and 38S. The rotary magnets'` thereupon operatev and advance the wipers oneV additionalstep. Relays 325i and 36s' then release after a' short delay due to their slow release" characteristics, and at make springs 322| and'sil open the locking circuits of the pulse absorbing relaysA whichflikewise restore and release the rotary magnets. Relays 320 and 36e also 322 and 323, and break contacts the wiper circuits to the selected such as fixed condensers of Elandt'close tuning elements, various values, inV4 andi transmitter;

To. talk,v the' oper-atm` atl the control station:V

. l32 is likewise open at break. it? how-- the associated radio receiverv first operates the press to talk key I0. This disconnects the loud-speaker amplier, and connects the telephone transmitter i3 directly across the line or talking conductors 30 and 3|. This closes a direct current circuit over both conductors in series as follows: ground through the lower winding of the battery feed relay l5, lower winding of the differential relay |30, lower left hand winding of repeating coil |38, conductor 3 I, lower winding of the telephone induction coil, transmitter i3, make contacts of key l0, conductor 30, upper left winding of repeating coil |38, and the upper winding of relays |35 and H5 to battery. Relay |15 operates over this circuit, but differential relay I3 does not, due to the fact that its windings are now energized in opposition. A circuit is therefore closed through make contacts lill for the operation of the talk listen relay 2.46. This circuit is as follows: ground through break contacts 3L make contacts H6, both right hand windings of repeating coil |38 in parallel, make contacts ||l| and |42, break contacts and |52, switch wipers and bank conn tacts, conductors 20|! and 25|, both left hand windings in parallel of repeating coil 235, and the winding of relay 2st to battery. This is the well known simplex method of control, and does not disturb the balance of the talking circuit, nor interfere with conversation.

Relay 240 upon operating. at break-make contacts 24| and 242 disconnects the speech circuit from the radio receiver and connects it to the radio transmitter input transformer, by way of the third patching jack and conductors 35i@ and 305. Relay 2d!! also, at make contacts 243 extends ground to the switch-talk conductor 309 by way of the lower patching jack. This operates a relay (not shown) in the transmitter which prepares it for speech in a well known manner. The operator now proceeds with the conversation, releasing key lll and relay 24|) as may be necessary, to listen to incoming speech.

To send Morse code, the operator plugs a telegraph key into the keying jack |8, if this has not already been done, and proceeds to tap out the code. Upon each closure of the telegraph key, a keying relay (not shown) in the transmitter is operated over the following circuit: ground at the key jack, through the telegraph key, over conductor make springs IMA, wiper |58, bank contact |89, conductor 258, the lower patching jack and conductor 3|l8 to the keying relay which automatically puts the code on the air. The press to talk key is left normal whenever the telegraph key is used.

If instead of being idle, the called radio unit is in use, or is otherwise made busy, ground instead of battery will be on test contact |94. When therefore, test wiper ist comes to rest on this contact, at the end of the rotary movement of the switch, this busy ground, which may come through the test wiper of another switch, or :from the make contacts 2|! on the busying relay 2li), or from the busying key 23e, will cause busy relay |23 in the switch to operate, by way of the wiper |93, and make contacts |51 on the rotary transfer relay. Relay |20 upon operating at make contacts |22 grounds the tone start lead HS, at make contacts |23 prepares a locking circuit for itself, at break contacts |23 opens the operate circuit of switching relay |45, at make contacts |21; prepares the automatic rotary circuit which is not required in this instance, and at break contacts H25 opens the regular pulsing circuit to the rotary magnet. Finally relay 10 at make contacts I2| connects busy tone to the line conductor 3| from conductor |28, by way of. break contacts |56 and |43. This busy tone passes through the receiver I4 of the calling telephone where it is audible to the operator, and then through condenser l5, conductor sil and the upper windings of relays |30 and H5 to battery and ground. up and try again later.

yControl station call to second group To initiate a radio call through a radio unit of the second group of units, the control station operator must, as previously indicated, use the quick select switch. Assuming for example, that the transmitter-receiver unit indicated in the drawings has been placed in the second group by plugging the patching cord 2M into the patching jacks 2|5, makecontacts 2|2 in the jack 2|5 will be closed, and therefore the associated lamp 2|3 will be lit, and the busying relay Elli will be operated. Relay 2|0, at its break-make contacts 2| l, will disconnect the upper winding of relay 23u from test conductor 253, and will connect ground to this conductor instead. This will make the associated radio unit busy in the banks of the stepping switches of all of the control stations, and prevent its seizure therefrom by dialing.

To make a call through this unit therefore, the operator at the control station has lmerely to remove the handset, thus operating relays tilt, ||l5 and lill, and set the quick select switch on its first contact. With the contact arms 2l and 2E on the first contacts, an alternating current circuit is closed through bot-h pairs of relays associated therewith, and all of these relays operate. Considering the upper pair of relays tot and Mil for example, the positive half cycles of current, if they may be assumed to be moving from left to right, will be opposed by rectifier disc 453 and must pass through the relay Mill, but they will be shunted around relay Mil by the rectifier disc M3 which is poled in the opposite direction to disc 403. Similarly, the negative half cycles of current will be opposed by disc M3 and thus forced through relay lili but will be shunted around relay 450 by disc 403. Both relays will therefore operate over the circuit eX- tending from ground at the first contact, through contact arm Z1, conductor 34, relays lila and M0, and the secondary of the alternating current source transformer to ground. The operation of the lower pair is similar.`

The quick select relays 400, 4H), 42o and 639 upon operating, at their upper make contacts connect ground to conductor 495 and to cut-off relay |50 which operates. Relay it@ upon operating, at break contacts |6| and |52 opens the switch talking circuit to wipers |81 and |89, and at break contacts H53 opens the dial tone circuit, which was closed upon the operation of relay lil. The quick select relays also, at their make contacts m2, M2, `||22 and 432 close direct current circuits to their dependent or slave relays Mii, |50, 450, 410 and 480. These latter relays are employed because of the fact that the heavy spring loads involved would be too much. for the controlling alternating current relays [tot to Mil.

Relays 44|), 45|), 460, 410 and 48|! upon operating, complete a speech circuit from the calling control station direct to the selected radio unit independently of the wipers of the stepping switch associated with the said control station. This circuit is from the control station telephone, over conductors 3!! and 3l. through the left bend The calling station must then hangv 1l windings ofthe repeating coil |38 and condenser |39, by induction to the right hand side of the repeating coil |38, conductors 493 and 494, make contacts 442 and 443, 45| and 453, 46| and 465, 41|I and 48|, conductors 496 and 491, patching jacks and cord, conductors 2 |1 and 2 I8, left hand Windingsnf repeating coil 2.35, by induction to the right hand windings of the repeating coil; break contacts V24| and 242, the upper patching jacks, and conductors 380 and 30| to the receiver output transformer 3|4. The channel selecting equipment is not aiected, and pulsing relays 3|0 and 35,0 remain normal. To talk, the operator has only to operate the press to talk switch in the usual way. This connects up battery feed relay .5. which operates and at the same time providescurrent for the telephone transmitter. Diiferential relay |30 remains unoperated as before and at break contacts |3| connects ground to the center point of repeating coil |38 byway of'make contacts ||6. This ground passes over the conductors 493 and 494 in parallel, and over the new talking circuit to the talk-listen relay 240, which operates to ground the switch talk conductor 309, and transfer the talking circuit from the radio receiver 3|3 to the transmitter 353. It cany then be transferred back and torth byreleasing and reoperating the press to talk key, as long as desired. If another control station operator wishes to come in on this connection, he may do so by setting his quick select switch also on its rst contacts. He cannot do sol by dialing however.

Control station call to attendant Assuming a single attendant station, and as suming likewise that the intercommunicating telephone associated with this attendant station is connected to the iirst contacts of the tenth level in the line banks or speech banks Vof the control station switches, the control station may communicate with the attendant over this phone by removing the handset in the usual Vmanner and dialing 01, f i

Upon the removal of the handset Vand the closing of cradle switch contacts I6, relays |00, |05 and I operate in the manner already described, and on the dialing of the first digit, the vertical magnet |21 responds to the pulsations of contacts |03 and elevates the wipers to the tenth'leve1. The normal post springs |49 will operate as the wipers reach the tenth level but without effeet. Transfer relay H0.. then restores, and transfers the pulsing circuit to the rotary magnet |32. The rotary magnet therefore responds to the second digit in the usual manner, and steps the wipers one step into the banks, ofwhich there are six, or one for each wiper. Relays |50Y and |55 operate as before, during the rotary stepping. In :this position line wipers |81 and |89 are connected to the left side of repeating coil 505 in Figure 5, by way of bank contacts 500 and 50|.and conductors 503 and 504, while test wiper |93 is connected to negative battery by way of bank contact 502, conductor 506, and resistor 501. The other wipers are now standing on contacts which are-vacant, except perhaps 'for the bank multiple from Athe corresponding contacts of the other control switches. Relays and |30 operate as before each time the dial goes on? normal and restore after each digit, withont effect.

If the attendant telephone is already in use, by a call from another control station, test wiper |93 will encounter direct ground from the other switch on the test contact on which it is standing, which ground will pass immediately through relays |00, |05

same battery, by way of break contacts |51 and |23 to the ground at make contacts |06, Switching relay |40 upon operating, at make contacts |4| and |42 extends the talking circuit through to the repeating coil 505, at break contacts |43 opens the busy tone circuit, at make contacts |46 connects direct ground to the test wiper, at make contacts |41 locks to ground from make contactsl |01.

To signal the attendant, the control station operator will now close the press to talk switch momentarily. This will again complete a direct cur-- rent loop circuit over conductors 30 and 3|, through the transmitter |3 and make contacts |0, for thev operation of the battery feed relay H5. RelayV |30, being again energized opposing, does not operate, and ground from break contacts |31,

passing through make contacts IIS, causes theoperation of signal `buzzer 5|2 and the lighting of signal lamp 5|3, by way of both right hand windings of repeating coil |38- in parallel, through contacts |4| and |42, |6| rand |62wipers |81 and |89, bank contacts 500 and 50|, conductors 503 and 504, left hand windings 0f repeating coil 5,05 in parallel, and break contacts 5| When the attendant answers, by removing the receiver or handset from the intercommunication telephone, not shown, a circuit is closed` over conductors 5|4 and 5|5, through back contacts of the answering key 554 and the right hand windings of repeating coil to battery feed relay 5|0. RelayA 5|0 operates over this circuit to, cut 01T the signals and at the same time furnishes talking battery to the `called telephone. The calling control station operator again operates the press to talk key each time he speaks, in order to connect talking battery from relay ||5 to his telephone transmitter.

To call the attendant station telephone of Figure 5 by means of the quick select switch, the control station operator, after removing the handset, will set the quick select switch` on its #15 contacts. On the removal of the handset, and ||0 will. operate in the usual way, and on the positioning of the quick select switch,rcontact arm 21 will encounter an open contact so that relays 400 and 4|!)` will remain normal, but contact arm 28 4will encounter nega- Ytive pulsations of current through the, rectier 26, which will cause the operation of relay 430 and its associated relays 410 and 48,0. Relay 430 also at make contacts 43| will pass ground to Cut-01T relay |60. which Will accordingly operate to cut off the dial tone and disconnect wipers |81 and |89. The speech circuit now extends from the right side of repeating coil |38 to the left side of repeatingv coil 508, by way of conduc- Y tors 493 and 494, break contacts 442. and 443, 452 and 454, 464 and 458, make contacts 418 and 488, and conductors 498 and 4.99 to the left side of repeating coil 598.

To signal the attendant, the control station operator will operate the press to talk key mo.- mentarily as before, to pperate battery feed re.- lay H5. This again connects ground from break Busy' :ontacts |3| to the center point of the repeating :oil |39. rlhis ground thereupon passes over both sides of the just traced speech circuit in parallel :o the center point of the repeating coil i508, and shence through break contacts 55| to the buzzer 552 and the signal. lamp 553. The buzzer buzzes and the lamp lights in response, as a signal to the attendant, who answers by removing the handset and operating key 555 down. This causes the operation of the battery feed relay V55|) to cut olf the signals, and completes the talking circuit between the two telephones as before.

In case a number of attendant station intercommunicating telephones are provided, they will be connected to successive contacts in the tenth levels of the control switches, starting with the first contact. In order to `provide automatic hunting of an idle telephone, it is necessary also, to strap the test Contact 502 of each such attendant telephone, except the last, to the corresponding eXtra test contact, corresponding to bank contact |91.

If now an operator at a control station dials l to call an attendant, and the rst attendant telephone is idle, the operation is exactly as described for a single telephone. If however, the first telephone is busy, the switch will continue to rotate in search of an idle telephone, and will give a busy signal only in case all of the telephones connected to the tenth level are busy. The action brielly is as follows.

When the control operator dials 0, after removing the handset and listening for dial tone, the vertical magnet |21 again raises the ywipt-:rs of the switch to the tenth level, whereupon the switch shaft again causes normal post springs |49, thereby connecting wiper |95 to the open make contacts |24 on the busy relay, to prepare the automatic rotary opthe operation of the ond digit 1, transfer relays |50 and |55 operate as before, and the rotary magnet |32 steps the wipers into the banks one step.

If the first telephone is busy, ground on the test contact thereof in the banks, will be passed to the busy relay |20 by way of test wiper |93 and make contacts |51. The busy relay |20 will thereupon operate, will open the switching relay circuit, open the pulsing circuit to the rotary magnet, and prepare the automatic rotary circuit, at .make contacts |24. Thus, when transfer relay |59 restores, shortly after the cessation of the rotary pulsing, and before transfer relay |55 can release, a circuit is completed for the operation of the interrupter relay |65 as follows: ground from the test Contact in the bank, through the strap connecting it to the associated extra test contact, wiper |95, make contacts of the normal post springs |49, make contacts |24, break contacts |i, make contacts |58, break contacts |33, and the winding of relay |55 to battery.

Interrupter relay IE5 upon operating over this circuit, at make contacts |56 locks to ground from make contacts |05, and at make contacts itl closes an obvious circuit to the rotary magnet |32, which operates and steps the wipers on to the next contacts. A branch of this `same circuit also passes through break contacts |53 to transfer relay |55 and prevents this relay from releasing. The operation of rotary magnet |32 opens break contacts |33, releasing relay |55. Relay itil in turn, opens the circuit to the rotary magnet which releases, and to relay |55 which however .being slow to release remains operated for an instant. If the next bank contact is also busy, wiper will still encounter ground, and interrupter relay |55 will again operate, re-energizing relay |55 and re-operating the rotary magnet. if all of the attendant phones are busy, relay |655 and magnet |32 will continue to operate alternately in this manner at high speed until the last contacts of the group are reached, which as previously stated, have no strapping between the test and eXtra test contacts. The extra test wiper |963 will therefore encounter an open contact, and the stepping will stop. Test wiper its however, will still encounter ground, thus maintaining busy relay |20 operated, and when transfer relay |55 releases after a slight delay, the lower contacts of the break-make-beiorebrealr springs i5? of this relay will 1cornplete a locking circuit for relay |20, by way of make springs |23 and itl. At the same time break contacts |5 close to complete the busy tone circuit.

lf the last attendant phone or .any intermediate phone is idle however, there will be only negative battery through a resistor such as 501 on its test contact. The rotary stepping will therefore stop at that point, and busy relay |20 will release. Transfer relay |55 will also release after the usual short delay, and switching relay |40 will immediately operate and lock and switch the talking circuit through to the wipers |81 and |99, whereupon the attendant may be signalled in the manner previously described.

Call ,from attendant stations The two motion switches associated with the attendant stations are identical with those associated with the regular control stations except for use of a special override conductor H9 leading from the attendant station to the lower eration. New when the operator dials the sec- Winding of the Switching relay ma and Special wiring t0 the bank contacts associated with the pulsing and test wipers |9l, |93 and |95, as indicated by the dotted conductors 204, 205 and Ztl, leading to bank contacts |92A, |9|A and IMA. The automatic rotary feature may also be omitted from these switches, though it may be retained to avoid the use of two different kinds of switches. An override button is provided at each attendant station, by means of which ground may be connected to conductor H9 when desired.

To initiate a call through a radio unit of the first group of units, the attendant removes the handset from the control telephone at the attendant station and on hearing the dial tone, dials the required two digits to select the desired unit, and then dials the third digit to select the channel, just as for a call from a regular control station. The operation of the switch in response to the first two digits dialled is also the same as described for calls from a regular control station.

Assuming that the called radio unit is the one shown in Figure 3 of the drawings, at the end of the rotary pulsing, wipers I8? and |89 will be on bank contacts |88 and |95, wipers |9i, |93 and |96 will be on bank contacts |92A, IMA and |9lA, and wiper |99 will be on bank contact |99. If this unit is idle, battery through the winding of cutoff relay 220 and the lower winding of hold relay 239 will be on test contact MMA. When therefore, transfer relays |50 and |55 release, shortly after the last rotary impulse, a circuit will be closed for switching relay |40 in series with relays 220 and 230 as follows: ground through make contacts |05, break contacts |23,`

15 upper winding of :relay rmt, upper vbreak oontacts of .the fbreak-make-:beoreibreak springs 151,;test wiper 493, :test fcontact i MA, conductor fiile, and the A'windings -of relaysl 22B rand 23B fin parallel Ito negative battery. lRelays ME?, .2211 and 39 all operateloventhiscircuit,

fsu/itching relay -Hm yupon operating, at rmakc contacts MI and rlfdlswitchesnthe `talking circuit through yto bank'contacts it and liihatmake contacts M4 extends ,the transmtter channelselect pulsing -:circuit through `ltoyifi'per y|95 'and .bank contact flili'nyand at make contacts M5 eX- .tends ytthe .receiver channel-'select pulsing circuit .through to wiper rdzl and bank contact ISZA. Relay .ttilfalsoatsmake contacts |46 extends di redt :ground 'to Wiper i533 `and bank -contzact HMA. filhe other funotions of 'the switching relay Vare as explained in previous sections. Cutoi relay 22u .upon operating, yat Amake contacts E25 and 222 entends the .channel-select pulsing circuits through to the pulsing conductors M32 and 36d and rtheassociated lpulsing `relays .'ilf and 355i. Relayzll also, at ibreak :contacts 22I andf'ZZd disconnects'conductors 22522 fand 286 4lliroin these circuits. Hold relay 123e upon operating, extends holdinugaground `to the hold conductors "3&3 and '3 ihinfthe usual manner.

When the-.attendant now dials the third digit, relays il iiiand i3d operate from the shunt springs as usual, as soon as the dial moves off normal, :and 4relay d'3@ at @make contacts 913i connects ground simultaneously ito fbothof the aforementioned channel-selectgpulsing lcircuits to relays Sill and 350. Both of these relaysthereupon .0perate immediately to release thechannel select switches in 4'the manner ,previously described. When the dial vis released, 'the resulting impulses drive the minor switches to a new position as before, in accordance With the digit dialled. When the dial again reaches normal following the last pulse, relays yH5 and jljil) release as before, and relay 131i again removes ground from make contacts `MH Yand W2 Vandhence frointhe channel-select pulsing circuits. 'Relays 310 and 3513 and their associated .relays then restore ,just as previously explained, andthe iminor switches advance one iinal step to compensateffor theabsorbed initial pulse. The talking ,circuit 'is switched from receiver to transmitter iin `the usual way by operating "the'ta'lk-listsen relayE-U over the speech circuit,

If `the called unit "is already in Vuse troni-another attendant station Vat `the time thiscallfis attempted, ground fromthe other switch will be on test contact IMA `and as soon as test 4wiper 93 lands on this contact busy relay i12@ willoperate and give 'the busysignal, and on'the release of transfer relay l'5'5 will lock throughfthe lower break 'contacts o'fsprings i5?. "Thesw'itch'ing relay Mll is at the same time preventedfrom operatingl by the open break contacts of the breakmake springs |23. .If the second attendant wishes 'to out in on the oonnectiomhe may do so at any time, by operating j'his override button. This connects ground to conductor iid rand to the 'lower winding of the .switching Arelay MU which operates and locks, cuts off vtheibusy .siga nal, and extends the speechand pulsing.circuits to the busy unit. 'The second attendant Vmay either listen or talk on this connection, or both, and may .if desired, release andrefpocitionthe minor switches of the said radio unit. .Theiirst attendant may ofcourse, ido likewise.

.If .the called unit-is inuse 1by affregular, control station it will ybe busy to -other'control stations,

'but :not stoitheattendantfstaticns, :bec'ausefof .fthx

.fact that a busying .ground `on L:bank conta'ct i119! is nctfcommunicated l.tozbankcontact -rI-SilAiin 2th:

attendantsfswitch. lFor fthis reason fthe attendants :switch would cut 4:through immediately or such :a fcall, `:from the 'battery on 'conductor 2115` and the .use of .the f override ibutton Awould lfn'ot be :required .Cutoff 'relay ,220 would operate tozextend lithe ,pulsing circuits .from "the ,attendant switch, and y:cut off Ythe; pulsing ,circuits .from the control switch. The attendant #station @may now release and reset vthe-channel select fs'witches iof the selected funit Iwithout interference A:from :the vcon-trol;station.

"If P'the ,:attendant Wishes to make :a Aradio call through ,a unit of the second group, the loperation :'isfsimilar. Busying relay 2izilxoi thefcalled unit will be .operated Yto ground the vassociated test contact, such 'as iid-ii, .'butthis ywill ,fnot `fairest the cci-responding test Contactin `thef-bankfof v.the attendants switch. VFor this area-son, avhe'n an attendant station calls such a unit, ,fit is again switched `through immediately, Vand may Jif gdesired folta-nge the channel Vsetti-ng of such unit at will :merely :by dialing :the required ithird :digit Alternative 1pulsing'scheme When thealternative pulsingscheme ofi-Figure 5 ,is 1 used, Athe .pulsing ,relays of the receiver `fand transmitterchannelselectingequipment.arernultipled together as indicated in Figure 5and connected to the upper :pulsing conductor a associated with the receiver, E,the `flower `pulsing .conductor being .connected to iground at ithe :transmitter channel-selecting equipment.

Now when .ya selector switch .extends Y a connec-r tionito .this channel selecting :equipment and the associated radio ,receiver v,and transmitter, the operation Vof :theswitching lrelay .M iollowing fthe dialing of .the .seconddigit immediately causes theoperation of :thekpulsingrelays 520'and 5&0'. fllhe V,circuit .farthese relays fis as vvfollows: ground from the radio `.transmitteron conductorfili, the lower ,patching jacks, break-contactson the make before break springs ,222, conductor 206.,1fbank Contact 19:7), .Wiper wt, vbreak x*contacts of `the normal post springs idd, makeioon-tacts(|44,-.make contacts tlllil .and 192, v.make contacts M5, wiper ,te l, ..bank.,conta.ct .1.92, conductor 2(92, break con tacts .of the make `before `break :springs 212i., through thei-second'patching jacks, conductor;3;2 and .the `windings `of .relays $520 and i560 in ,par-- allel.

Pulsing `relays 52.0 .and 5.66 upon operating, close fobvious circuits to release relays t536 .and 5th ,which also operate, to openrthe release circuits ,and prepare I,the Astepping circuits. ,New when the channel selectingadigitis jdialledeach releaseof ,pulsing .relay i'rzcauses-a correspond'- ing release of v:pulsing relays 522,0 andilhfthrough the Liliterruptions v.of .make contacts :isl and I rZ. The slow release Wiper-guard relays 549 and n-rst pulse and 'release shortly after the .last pulse to-keepy-the vwipersfopen-dur- Ving the stepping. ,The :rotaryPmagnetffopera-tes on .the .first pulse Neandhon eachsuccessive pulse, wiper-guardrelays. Therelease Arelays being lalso slow 'tofrelease .are snot outwardly affected by the pulsing. Atthe termination `rof 7.the call, when -t-he vconnection .is re'- leased, pulsing :relays 52.0 ,and :560 also release. The yrelease crelays, due to :their slow release qualities, :remain operated :for .san instant, per mitting @the twiper guard v.relays and 'the rotary magnets tobefagainrznomentarily. energized. im

mediately thereafter however the release relays restore and at their break contacts close circuits to the release magnets which operate and restore the wipers to their normal position. As each switch reaches normal, its off normal springs open and open the release circuit.

It will be apparent that the two motion stepping switches herein described may also be utif lized to extend calls to an automatic telephone switchboard such` as ,a PAX, `provided only that such automatic switchboard pass ground back to the bottom pulsing wiper when seized from such switch. Thus for conductors would be required to the automatic switchboard instead of the more` usual three conductors. l

What is claimed is:

1. In a remote control system, a rst and a second control station, a rst and a second selector switch associated respectively with Isaid control stations in the order named, `a plurality of multi-channel radio units each including a radio transmitter and receiver, `channel selecting devices associated with each said radio unit, a pulse` repeating circuit in each said selector switch, an impulsing device at each` said control station for operating the associated selector switch to select any one of said multi-channel units,` 4means in said rst `selector switch to extend the associated pulse repeating circuit to such selected unit if it is free and to prevent such `ex` tension ifsaid selected unit is in use, means in said second selector switch to` extend the associated pulse repeating circuit to such selected unit whether it is in use or not, and means to repeat` further impulses -from` said impulsing devices over said extended pulse repeating circuits to position the channel selecting devices of `said selected'unit. In a switching system, a rst and a second control station, a first and a secondselector switch associated respectively with saidV control stations, a` plurality of multi-channel radio units each including a radio receiver and a radio transmitter, a channel selecting device associated with' each said transmitter and each said receiver, a` pulse repeating circuit `in `each said selector switch, a speech circuit `from each said controly station to its associated selector switch,` an img"` pulsing device at eachl said control station for operating the associated selector switch to select` any one of saidmulti-channel units, meansin" saidnrst selectorswitch to then extend the associated speechand pulse repeating circuitsto` suchselected unit only if it isnotinuse, means in said second selecter to extendthe associated speechand pulse repeatingcircuits to such sen lected unit regardless of its condition of' use, means to repeat further impulses from said im# pulsingdevices over said extended pulse repeating circuits to the channel selecting devices of such selectedunits `for operating such devices,` and means responsive to the selection of a busy unit `by said second selector switch to `disable the" pulse repeating circuits from said rst selector switch to prevent interference` `3. In a switching system, a control station, a control selector associated therewith, an' attendant station, an attendant `selector associated therewith, a plurality of multi-channel radio units, a `radio receiver and a radio transmitter in, each said unit, channel selectingdevices associated with each said unit, a speech circuit and a pulse repeating circuit associated with each said selector, an impulsing device atsaid control station for operating the associated selector to select any one of said radio units or said attendant station, means responsive to the selection of an idle one of said units by said control selector to extend the associated speech and pulse repeating circuits to said idle unit, means responsive to the selection of a busy one of said units by said control selector for preventing the extension of said speech and pulse repeating circuits to said busy unit and for giving a busy signal to the calling control station, an impulsing device at said attendant station for operating the associated selector to select any one of said units, means responsive to the selection of any one of said units by said attendant selector to extend the associated speech and pulse repeating circuit to such unit even when busy, means to repeat further impulses over the 4said extended pulse repeating circuits to operate the channel selecting devices of the selected unit, and means responsive to the selection of the attendant station by said control switch to extend the associated speech circuit to said attendantstation if idle, for purposes of intercom munication.

Ll. In a radio` switching system, a control station, a two-motion switch associated with said control station, a plurality of `attendant stations accessible to said control switch, a two-motion switch,` associated with each said attendant sta-` tion, a plurality of` multi-channel radio units ac-` cessible to any of said switches, a radio receiver; and a radio transmitter inleach said unit, channel selecting` devices associated with each said unit, a speech circuit and a pulse repeating circuit ineach said switch, an impulsing device at said control station for transmitting impulses to the associated two motion switch to cause `said switch to select any one of said radio units or one of said attendant stations, means responsive to the selec-Y tion of 'an idle one of said radio units by said control switch to extend the associated speech 'andi pulse repeating circuits to said idle unit, an im.- pulsing device at each of said attendant stations for transmitting impulses to the associated two motion switchto cause said switch to select any' one of said radio units, means responsive to the selection of any one of said units by said attend` ant switch to extend the associated speech and pulse repeating circuits to said selected unit even if said selected unit is busy,

such last mentioned extended pulse repeating circuit to the channel selecting devices of such se,` lected; `unit for operating and positioningsaid, last named` devices, means responsive to the selec tion of an idle attendant` stationby said control i switch to extend `the associated speech circuit to said` idleattendant station, means responsive `to attendant stations are busy.

, `5. In a radio telephone switching system,

therewith, a -second control station, a second step--` ping switchassociatedtherewith, a rst group of radio units, a second group oi radio units, `a radio ,y

receiver and a radio `transmitter in each of said units, ka speech circuit extending from each said*v control `station toits associated stepping switchh` impulsing means at said rst control station to` operate said first stepping-switch to selectwany one of said radio` unitsj means to repeat fur-` ther impulses from said impulsing devices ovei-` i a ISt control station, a rst stepping switch associatedl meansl to thereupon exe"` tend the associated speech circuit to the receivers;

smeert ofi-said selected runit onlyfincasesaid'selected. unit isrin the firstgrouplandfisu-idle;impulsing means at said second control, stationsfor operating said secondstepping switchS-to-select :any one of said radio units,A means to thereupon extend-the associated'speech circuit tothetreceiver ofsaid selected-unit regardlessoffthe group involved and 'regardless of the condition yxofguseof said selected unit-a relay associatedwith'f each said unit, and means for operatingrsuchfrelay Aat lwill from the calling control f stationV over L-suchA extended speech circuit, to transferthe` extended speech circuit from the receiver tol theftransmitter of the selected unit; v

' 6J Ina radio switchingasystem, arst control station; a secondlscontrol station, a first and a second `two-.motion selector switch `associated* respectively lwith1said--, stations, :aifirst .and 'a second groupY ot radio 'units aradiofireceiver and a radio transmitter in-:each'OfsaidffunitS;4 a pulsing circui-t, aspeechcircuitlandseJ telegraph circuit extending from eachisaid vcontrolistation to itsassociated selector switch; impulsing means. at each said station' for:operating@the'oassociated switch over the associatedwpulsingicircuit toselect any orient-.said-radio.uni-ts;'Jmeansgesponsive to such selectionby saidsrst selector switch toty extend thetassoc-iate'd. speechncircuitfto. the receiver of the selected :unit andcthezf associated telegraph circ-uit: to.` the. transmitter thereof :provided such selected',y unit isa-bothfinntheffrst group andis idle, means responsive tosuchrselection bysaid second selectorgfor.; extending the ;associated; speech circuit to the receiverixandifthe associated telegraph' circuit to (the transmittereoi y.the selected lunit;` regardless of the group-involved; .and regardless oi'thefbusy condition,otsuchzselected unit, a relay associated wit-h'.aeachsaid:.funit;zfa fcircuit means controlled,irorrnthepA calling: controlv station over the. .1 extended, speech= "cirouitrforr` yoperating f said reiayto transfer; said'.- extended .speech circuit to the,transmitterrotthe; select-edfunitand to ycondition ,said j stransmitter :fortthe transmission of speech,,and cont-rolmeans .eatfsaid stations to `*perrnitl then subsequent vrelease'ianderemperationfof,y saidffrel'ay over saidlcircuitmeansfas"required duringf'the ./connectionn:

-'7. In a radio switching system, .acontrol sta;l

tion;v a fselectorsswitchgfgwipersf-lon sa-idswitch; a

speech circuit andapulsingcircuit extending be-L tween saidcontrol.stationvandzsaid switch, a iirst groupy of-l radio units ;accessible1;.tofsaid' Wipers, a

second group tof radiosunitsalsoaaccessible to .said

Wipers but ymade articiallyifbusy"thereto, van irnpulsing i device-at said` control station for operatev :circuit to select` any-one of said units, means :responsive vonly to.; the selection of \an-id1`e" :unitll'inrsaid irst groupy ing said switchA overV` -said'fpulsing to=extend said speech circuit throughthe wipers ofsaid sWitchJ-to such selected' unit, a radio `receiver and a radio transmitter in' eachsaid unit# means 'controllable over saidspeechfcircuit forv switching said speechcircuitiiba'ck'and fortlfrioe-v tween the receivenandV transmitter-of said selected unit as required for radio communication, ajquick select: handfoperated'y vswit'chat, said control station; quick select vrelays `yforsaid last mentioned switch; and meansrcontrolled' by said quickl select switch'ior operating saidirelays in various combinations -to extendrsaidi'sp'eech *circuit directvv to anyone-of said uni-tsinv-said second group, in-

dependently of the wipers 'ofi saidrselector switch;

SffIn a radio switchingfsyst'em; `a control Sta-- tion,` a vselector switch;ywipers-ion'v'said-fswitch;y ay

speech `icir'cuitfand fa pulsing "circuits extending;

between u said. contrer: station/s and@ said? selector switch, a.. rst vgroupof-:'1adio units @accessible-to the Wipers of said selector switch, a :second `'grcmp of vradio unitsvalso accessible'rtoisaid lwipers but made artiiciallylbusy -thereto`,an`impulsing device at said control station-"fory operatingsaid--switch over said pulsing circuit` to select'y anyone lof said units,r means responsive only -to thel selection-fof an idle unit in said rst group byfsaidl-Wipers' to extend saidspeech circuit through! said wipersv to such selected vunit',A a multi-point-handop erated switch at saidV control station; means -c0n'` trolled by positioning said multi-point switchfor extending said speech circuit from said control station direct to any one *rof'fsaidiunits in-said second group independentlywof said* wipers, a radio receiver and aradio transmitterineach radio unit, means controllable from said control station over either-of fsaid' extended Speech Voir# cuits for switching said speech circuit backand forth between the receiver and transmitter ofthe unit involved;` Aand v a- -cross connecting arrange# ment forv quickly transferringany' of `the-unitsl ot? said second group to said rstgroup and remov' ing the busycondition therefrom.-

9. In a remote control system, a first control station, 'a second controlfstation,l a "rst selector switch associated with 'said-first^station, a sec'-V ond selector switch associated f with said second station, a speech circuit and 'apulsing circuit ex;` tending` between each said "control stationand its associated selectorswitch, wipers on each saidA selector switch, a iirst anda Vsecond group of radio' transmitterreceiver units, aneV impulsing f device at each said control station for-operating'the as-` sociated selector switch over the associated pulse" ing circuitto'select any one of said-transmitter@ receiver units,A means in said rst'switch re-'f sponsive onlypto the selectiontherebyjof an idle unit in said rst groupto 'extend the' associatedv speech, circuit` through i the wipers" o1=` lsaid firstl switch to suchjselecteduniht means in said sec? ond` switch `re'sponsiverto vthe fselection thereby" of anyunit in',eitherofsaid groups tolextend .th'e associatedA speech [circuit "through the wipers fof said second switch to` such selected vunit even ifbusy,v a quick select. circuit 'for said rst selector switch, avmanually operatedtmultiepoint contact' switch Vat said rst, ,controlv station for operatingv said. quick select circuit, to extend the speech ein# cuit ofsaidrst control station to `any unit of said' second group independently ofthe ywipers of saidv rst selector switch, and. means s in. said rst vsel-jvv lector switchvto extend the/speech circuit of Said..

Q rst .control station, to-saidrsecond .controlfstai-.f

tion., either through the wipers of said rstswitch or through` said quiekselect` circuitlj.v

10. `In a -remotecontrol system, a ,rstjcon-trol.4 station,V -va/ second controlfstation \a Jiirst stepping;y switch associated f with vsaidlfirst .-station, a ,secondi stepping switch associated with .saidlsecond sta-9, tion, a yspeech circuit 1associatedWith\. each said; control 'i stations wipersy` on; Yeach ,said stepping., switch, a first and asecondigroupzofvradio units,l`, azradio; f receiverA and a radio, transmitterfinf'each off esaid-Emuita@:an:[email protected] said, control @station-.for :opevating 'the associated-- steppingy switch tof/select any?, one of said I. radici! units meansiinffsaidirst steppingfz'switchref spon'sive-corrly. =toi the selections thereby; ofi an idle-z unitT inV S said rst'f groupitoextend the speech 'cir-.A cuitf'ofa said! iirst'stationi through tiles-wipers i of? said .'/iirstzswitch saidlsecond#switch fsuchfselectedgunit,:means sin?.

thereby of any unit regardless of the group involved and regardless of the condition of use of such unit to extend the speech `circuit of said second station through the wipers of `said second switch to such selected unit, a quick select relay circuit in said rst switch, a manually operated multi-point contact switch at said first control station for operating said relay circuit to select any radiounit in said second group and extend the speech circuit oi said first station thereto independently of the wipers of said first stepping switch, means controlled over any of such extended speech circuits to switch such circuit back and forth between the receiverand transmitter of the selected unit as required, means to extend the speech circuit of said first control station to said second control station through the wipers of said first switch, means to extend the speech circuit of said first control station to said second control station through said quick select circuit, and means to signal said second station over each of said two last named extended speech circuits.

` `11. In a remote control system, a first group of control station-s, a second group of control stations, a selector switch and a speech circuit associated with each of said -control stations, wipers on said switches, a rst group of radio transmitter and receiver units, a second group of radio transmitter and receiver units, impulse responsive Y means for extending the speech circuit of any one of said first group of stations through the wipers of the associated selector switch to any idle radio unit in said rst group of units but not to a unit inVsaid second group of units, impulse responsive means for extending the speech cir-cuit of `.any one of said second group of stations through the wipers oi the associated selector switch to any idle radio unit in either group of units and for extending such speech circuit to any busy radio unit in either group of units if in use by one of said first group of control stations but not if in use by one of said second group of control sta' tions, and other means for extending the speech circuit of any one of said second group of control stations through the wipers of the associated selector switch, if desired, to any busy radio unit even when in use by another control station in said second group of stations. i

l2. Ina remote control system, a radio transmitter and a radio receiver, a control station, an impulse dial at said control station, a two-motion selector switch, a pulsing relay and a local `pulsing circuit in said two-motion switch operated in response to impulses from said impulse dial to cause said selector to seize said radio transmitter and receiver, separate pulse repeating circuits extended to said transmitter and receiver in response to the seizure of said transmitter and receiver by said two motion switch, means in said two motion switch including separate pairs of pulse repeating Contacts on said pulsing relai7 for repeating further impulses from said impulse dial over both of said pulse repeating circuit-s simultaneously, and means for energizing such circuits during such further pulsing only while said dial is oli normal.

13. In a remote control system, a first and la second radio transmitter and receiver unit, an impulse dial, a two motion selector switch, a lpulsing relay in said switch operated in response to impulses from said dial to cause said selector switch to seize either of said transmitter and receiver units depending on the number dialled, a pulse repeating circuit comprising two conductors extended to either of said transmitter and receiver units in response to theseizure thereof by said selector switch, a first and a second impulse receiving set associated respectively with said transmitter and receiver units, means responsive to the seizure of said first transmitter and receiver unit to cause further impulses from said dial to be repeated by said pulsing relay to said first impulse receiving set over both conductors of said pulse repeating circuit simultaneously and for energizing the conductors of said pulse repeating circuit during such further impulsing only while said dial is off normal, and means responsive to the seizure of said second transmitter and receiver unit tocause such further impulses to be repeated Iby said pulsing relay to said second impulse receiving set over -only one conductor of said pulse repeating circuit and for energizing said one conductor immediately upon the seizure of said second transmitter and receiver unit by said selector switch.` i v i 14. In a remote control system, a plurality of control stations, a two-motion selector switch associated with each said control station; an im' pulsing "circuit,a speech circuit, and a telegraph circuit extending from` each said control station to its associated two-motion switch; impulse repeating circuits in said` switches, a plurality of multi-channel radio units, a radio transmitter and a radio receiver in each of said units, a channel selecting device associated with each -said transmitter and each said receiver, an impulsing device at each said control station for operating the associated two motion switch over said impulsing circuit to fselect any one of said multi-channel unitsmeansto then extend said speech and telegraph circuits and at least one of` said impulse repeating circuits to said selected unit if it is `idle and to prevent such extension if said -selected unit is in use, and means to repeat further impulses `from said impulsing` device over said extended pulse repeating circuit or circuits to position the channel selecting devices of said selected multi-channel unit simultaneously.

15. In a radio switchingsystem, a plurality of control stations, a control switch associated with each said control station, an attendant station, an attendant switch associated therewith, a talking -circuit between feachof said stations and its associated switch, an impulsin-g device at each said station, a pulse repeating circuit in each said switch, a plurality of multi-channel radio units, a radio transmitter and a radio receiver in each of said units, a channel selecting switch associated with each said transmitter and each said receiver, means to pass impulses from the impulsing device at any one of said stations to the associated switch and thereby operate said switch to select any desired one of said radio units, means responsive to the selection of a free unit vby an operated control switch to extend the associated talking and pulse repeating circuits to said free unit, means for repeating further impulses from the impulsing device at the associated control station over said extended pulse repeating circuit to the channel selecting switches of said selected unit to position said switches, means responsive to the selection of a busy unit by said operated control switch for preventing such extension of said talking and pulse repeating circuits and for giving a busy signal to the calling control station, means responsive to the selection of any one of said units by an operated attendant switch to extend the associated talking and pulse repeating circuits to such selected unit tion,v a plurality ofy radio' units;L a.; radio transmitter and a radio receiver. in each of.. said units, afpair of relays connectedin series, a second pair off relays connected in"` series, a rectifierv discv connectedl in. shunt withY each ofisaid relays, the; rectier discsof each pair of relays being also con:- nected in series with eachrotherbut pcled oppositely` with respect to'eachzothen.'an` alternating current source connected tofeachpairof relays, a

multi-point hand operated switch havingdiierent. positions for operatingy said relays.; inl` diierentcombinations-from said alternating current source to select" any one. of. saidradio units,. a speech circuit, means. operated by such' operated relay combination for extending4 said'- speech circuit from saidl control station t'o-such selected radio unit, and means controlled over said eX- tended speech' circuit for switching said speech circuit back and forth at will between the receiver and transmitter of saidselected unitas required for two way radiocommunioation.

17. In aremotecontrol system, a pluralityl of radio units` fortwo wayradio communication,A a control. station, a speech" circuit associated with said control station, a pair of relays connected; in series, a rectifier disc. connectedy in shunt with eachv of said relays and? poledoppositely withvre, spect to each other, anothervpairot relays arsa-id terminals to one sidefof eachvv ofvk said pairs of series relays, a handoperated: s witch at said controll stationv having a; plurality ofpositions,

lays; other rectifier discs, aV plurality of contacts .for each of saidfcontact arms.,- some oil saidcon.- tacts being connected to the other. terminalfof said source directly, some offsaid contacts beingconnected to said other terminal throughdiiferently poledones of saidI other; rectierdiscs,vand others oi said; contacts being left-open,y said' contact.` conandere trol stationto any-desired'one of; said radio units asidete'rmined4 by the setting of said -switch contactarlns on said contacts;

18.` Inxa remote control'system, a radio: trans- Init-tenand, a ,radioreceiven impulse responsive relaysyandstepping switches; associated with. said transmitter and receiver, a control station, an impulse dial.y atfsaid-control station, atwo. motion energizinglsaid pulse repeatingcircuits when said dialis moved off normal to initiate such further, impulses, said stepping switches being released EDWARDsPETERsoN.

REFERENCES CITED:

The'. following referenices are of record` in the ille of this; patent:

UNITED STATES PA'I'ENTS Number Bowers Dec. 2, 1941

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