Title:
Radio switching system
United States Patent 2475675


Abstract:
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...



Inventors:
Peterson, Edward S.
Application Number:
US67267746A
Publication Date:
07/12/1949
Filing Date:
05/27/1946
Assignee:
Automatic, Elect Lab
Primary Class:
Other Classes:
178/2R, 340/12.15, 379/311, 455/403
International Classes:
H04W99/00
View Patent Images:
US Patent References:



Description:

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. 2 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 2 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 S 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 p.tch cords, whereby any unit can be transferred f rom 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. It 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 Scontrol 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 0 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.

i0 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 I1, and a telegraph keying jack 18 for sending Morse code if desired. The telephone is preferably of the 35 handset type, with a press-to-talk button 10 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 40 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 sys45 tems. The vertical magnet 121 may be seen in the lower central part of Figure 1, the rotary magnet 132 at the lower right and the release magnet 104 at the lower left. A talking circuit is shown in the upper part of Figure 1 and the 50 wipers and bank contacts at the extreme right.

Eleven relays are also shown in this figure, including a pulsing relay 100, a release relay 105, a vertical transfer relay 110, a battery feed line relay 115, a busy relay 120, a differential line 55 relay 130, a switching relay 140, rotary transfer relays 150 and 155, a cut-off relay 160, and rotary interrupter relay 165. The attendant sta tion has a switch similar to that used for contrc stations, except for a special over-ride conducto 8 1, and special connections to the pulsing am test bank contacts such as indicated at 192A 194A and 197A. It may or may not be provide( with quick select equipment.

In Figure 2, the talking circuit and the fou: control relays normally associated with a par. ticular receiver-transmitter unit are shown con. nected to a particular set of bank contacts in tht 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 of the relays.

By plugging patching cords into these jacks, in case of trouble for example, the normally associated unit can be quickly disconnected and a different unit connected up in its place, the various jack contacts being opened upon the insertion _of the plugs of the patching cord into the jacks, and the circuits connected straight through. At the lower left of Figure 2 is indicated another set of patching jacks for connecting the required radio units to the quick select circuits of the stepping switches. The talking circuit of each unit is multipled to several jacks in the upper:row, while the quick select circuits f the different stepping switches are connected individually to the jacks of the ..lower row. This permits several.control stations to come in on the same unit over this path at the same time.

When a patch cord .such as 214 is plugged into an upper jack such .as 21:5, a busy lamp such as 213 is lighted, and busying relay 210 is operated.

The other control relays.are a cutoff relay 220, a hold relay 230, and a talk-listen relay 240.

In Figure.3, the rectangles 313 and 353 represent a radio receiver and a radio transmitter making up a single radio.unit. Identical channel selecting circuits, comprising four relays and a ten point stepping switch commonly known in automatic telephone practice as a minor switch, are indicated in. schematic form in, each rectangle.

Relays ,3 0 and 350 are pulsing relays, relays 320 and 360 are wiper guarding relays, relays 330, 340, 370 and 380 are pulse absorbing relays, and the minor switches are indicated under the brackets 3.15 and 355. Four leads are shown , going to the receiver from the switching and control equipment, namely:a pair.of incoming speech leads 3l0 and 31 terminating in the receiver output transformer 314,,a Pulsing 'conductr 32, and a locking conductor ,393, which is required only when the channelsto be-selectedexceed ten.

Similarly, six leads go to the transmitter from the switching and control .equipment: a pair of outgoing speech leads terminating in the transmitter input transformer 254, a locking conduc- G( tor 306, apulsing conductor 307, a telegraph conductor 308 which goes to a keying relay, and a switch talk conductor 309g whose function is to prepare the transmitter to handle speech. The radio circuits themselves are not shown, since 65 they form no Part of the invention.

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 this switch is connected to a pair of combi- 70 nation -relays 400 and 410, and 420 and 430, the relays of each pair being wired in series with each other and .in shunt with oppositely poled dry disc rectifiers. The other side of each Pair of relays is taken to a grounded source of alternating cur- 75 a rent such as the transformer 409. The contacts of the quick select switch are connected to direct r ground, to ground through a dry disc rectifier r such as 25 poled to pass positive half cycles of 1 5 current, to ground through a dry disc rectifier S such as 28 poled to pass negative half cycles of current, or are simply left open. Thus, for different settings of the contact arms, which are r arranged to move together as a unit, the relays - 1040 to 430 and their dependent or slave relays 449 to 480 are operated in different combinations to make the required selection. Direct ground on a contact arm, for example, will cause alternating 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 rectifier disc 25, will cause the first relay of the associated pair 0 tooperate, and negative half cycles through rectifier disc 2 will cause the second relay only, to operate, by the bucking and shunting effect of the discs associated therewith.

A total of fifteen relay combinations and fifSteen selections are made possible with the equipment indicated It will be apparent however, that by the use of additional pairs of relays and a gangswitch with more contact arms and more contacts, or by using a bank of keys or push *n buttons instead of.a contact switch, this number could be increased materially. The complete list of combinations used herein is shown in the followingtable: Switch Relays Position Opelays 1i.... Operated - --- _ ------- --- 400, 410, 420, 430 S--- -- -------- 400, 410, 420 3 - --- -----.-- 400, 410, 430 -------- ------- 400, 410 40 5-----.-------------- 400, 420, 430 7 ----.--- 400, 420, 430 .------------ -- 400, 4230 _ ----------.- 41:00, 430 8..______._......._.__ ....... 40 - --------.--___.....- 4610, 43 12----------------------- 410 12-----i----------;-;----450 13 -------- ----- 429, 430 :0 -..------ --------- 420 0 15i -- -------_-.. 430 In Figure 5, the equipment at the left is the intercommunicating equipment required at the attendant station. The upper portion is for calls 5 made through the banks of the stepping switches, and the lower portion for calls made by way of the quick select relays. Separate repeating coils 505 and 508 are employed, together with separate signal buzzers 512 and 152, separate signal lamps S513 and 553 and separate battery feed relays 510 and 550. The attendant's 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 it is assumed here to be a separate instrument.

In the case of several attendant stations, a quick select circuit could be assigned to each, thus reducing the number of circuits available for radio selections over this path, or a single quick select circuit could be made available 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 3 luipment of the radio units. In case it is de- 3 red to release the channel setting minor vitches at the end of each call, upon release of e ie connection, a circuit such as this is necessary. , c a the channel select circuit of Figure 3, the r linor switches remain in the last operated posiion 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 10 1 ,re the pulsing relays, relays 530 and 570 are reease relays, and relays 540 and 580 are wiper uarding relays. The minor switches, which are dentical with those of Figure 3, are indicated by he numbers 525 and 565. The same leads are :equired to these circuits also, as for those of Figure 3 but the pulse lead to the transmitter is ,onnected therein to ground rather than to the pulsing relay, which is now in multiple with that f the receiver. Both ty es of channel selecting 20 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 25 a control station, to initiate a radio call through a radio unit of the first group, removes the handset from the telephone, thereby causing the cradle switch 16 to close its contacts. This causes pulsing relay 100 to operate from ground 30 at the cradle switch, by way of the dial impulse springs 19, and conductor 32. Relay 100 upon operating, closes make contacts 11 and 102, but without effect at the moment, and at make contacts 103 closes an obvious circuit to release relay 3h 105 which operates. Release relay 105 upon operating, closes make contacts I10 and 101, but without immediate effect; at break contacts 101 disconnects ground from the release circuit now open at vertical off normal springs 114; at make contacts 109 prepares a local pulsing circuit; and at make contacts 108 e a closes circuit to the lower winding of vertical transfer relay 110, by way of the normally closed vertical off-normal springs Transfer relay 110 upon operating, at make contacts 113 prepares the vertical magnet stepping circuit and at make contacts 112 connects starting ground to the tone start conductor 119 which leads to a dial-and-busy-tone unit, not F shown, such as commonly used in small automatic 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 dia]-tone conductor 129 whence it passes through the closed break contacts 163 and the closed make contacts III to the talking conductor 31, through the receiver 14 and condenser 15 of the calling telephone, and back over talking conductor 30 to grounded battery through the upper winding of relay 115. 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 128 by the tone unit at this time, but this is without effect, due to the open make contacts 121 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 first 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 0 and 31. The ground on the lower conductor I shunts the lower windings of relays 115 and 30, while the ground on the upper conductor nergizes the upper windings of these relays, and auses them to operate in series. Both of these elays operate and close their make contacts 116 ind 131, but without effect at this time.

The dial 17 upon being released, returns to normal and at its impulse springs 19 interrupts ;he circuit of the operated pulsing relay 100 the required number of times, depending on the digit dialed. The pulsing relay 100 follows these dial purses and reverses the position of its contacts a corresponding number of times. Contacts 101 and 102 are still without effect, due to the open make contacis 144 and 145 on the switching relay.

Break contacts 153 of relay 100, however, repeat the dial pulses by way of make contacts 109 and 13 to the vertical magnet 127 and the upper winding of relay 110 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.

At the first step, the vertical off normal springs 117 shift position and open the operate circuit to the lower winding of relay 10 which is now held through its upper winding. The circuits of relays 105 and 118 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 again, the dial shunt springs open, and release relays I I5 and 130, and the impulse springs close and remain closed, thereby holding relay 100.

Transfer relay rI after a short delay now releases, and at break-make contacts 113 disconnects the now open pulsing circuit from the vertical magnet 121 and connects it to the rotary magnet 132. Relay 11 0 also at make contacts I II disconnects the dial tone from the line and at make contacts 112 removes ground from the tone ; 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 115 and 130 to operate in series over their upper windings. Upon the release of the dial, impulse springs 19 again interrupt the circuit of relay ISO ;5 intermittently, and this relay follows the pulses as before. Upon the first release of relay 100 at the start of the second series of impulses, a circuit is closed to the rotary magnet 132 as follows: ground at break contacts 153, make contacts 109, break contacts 113, break contacts 125, 148 and 167, and the winding of magnet 132 to negative battery. A branch of this circuit also passes through the winding of rotary transfer relay 150. Relay fS and the rotary magnet thereupon both operate. Relay 150, at break contacts 151 disables the circuit of the interrupter relay 165, at make contacts 152 closes a shunt around break contacts 125 and 148 to prevent interference with the pulsing by the busy and switching relays, and at make contacts 153 closes an obvious circuit to rotary transfer relay 155, which also operates.

Transfer relay 1S5 upon operating closes make springs 158, but without effect, and at breakmake contacts 157 momentarily disables the operate circuit of the switching relay 140 and prepares a., circuit: for the. busy- relay 120.. The rotary, magnet now operates intermittently in response' to: the pulses, and at each operation rotates. the wipers into the- selected level in the switch bank: until the bank contacts of the selected radio- unit, such; as the contacts 188 etc. shown in Figure I arereached. Transfer relay 150 remains operated during the pulse interruptions, since it also is made slow to release through the use:: of a copper sleeve over-the core., At the end- of the second digit, pulsing relay 900 remains, operated as before; and relays 1195 and 130: again: release, without effect. Transfer relay 5 10 also releases, after a short: delay, and opens the circuit of transfer:relay 155 which also releases, after a still further short delay, since it also is made slow to release.

Assuming.that,the called unit is not in use, and is not otherwise made busy, test contact 194 in the switch bank will have negative battery on it, through the upper winding of the hold relay 230.

Upon'. the. releases of rotary transfer relay 155 therefbre,.the: closing of break: contacts 151 completes a circuit for the operation of switching relay. 140in series with.relay-238 as follows: ground 2 at imake ,contacts 9i06; break contacts 123, upper winding. of relay 140, break contacts 17;, test wiper 19., test contact: 19'4 conductor 203, busying, key 23,. break,: contacts 211, and the upper winding-:of'relay.-230:tb battery. Relay 230 upon 31 operating, extends ground from make contacts23:1 and. 232: through; the patching jacks to the hold conductors 3031 and% 306. Relay 140 upon operating,, at: make: contacts 147, locks to ground at" make: contacts. 107, and at break contacts 148 disables the pulsing circuit to rotary magnet 132.

Switching: relay 140 also at. make contacts 141 and 142 -extends the: talking: circuit from the calling control station to the receiver of the selected radio unit. This circuit is: from the line conductors 30 and: 31, through the repeating coil 638, make contacts 19 4 and 142, break contacts 161 and 162, switch wipers 187 and 189, bank contacts: 18:88 and' 191,. conductors 200 and 201, through the. repeating coil 235, break contacts 4 241:1 and 242; the upper patching jacks, and conductors 300h and 301 to: the output transformer 314 in the receiver 13. Relay 140 also, at break, contacts: 143 disconnects. the, busy tone circuit, at: make: contacts 1944 and- 145F prepares circuits fbr the unit pulsing, relays 310 and 350, and at. make contacts: 146 connects direct ground to the test wiper' 193, to' make: the called unit busy to the other- control stations.

The onerator at: the calling control station now dials the third or-channel selecting digit. When the: dial' moves. off normal, relays: 115 and 130 again operate ini series over their upper windings as :before. This time; the operation of relay 1 15 is still withoutf immediate effect, but relay 3 upon: operating- closes: separate pulsing circuits to, relays. 3-18 and- 350. h The circuit to relay 310 is- from: ground at make contacts 131 through make contacts 102; make.contacts 145, wiper 191, banke contact 121, conductor 202, break contacts 65 t 221, secondt patching jack, conductor 302, and r the winding of relay 33 .to battery. The circuit a for relay 350e is, from the same ground at make s contacts I-Sl through make contacts 10 and 144 tJ Ibrerk contact's. of the normal post springs 149, 70 a wiper, I9S, bank contacts 197; conductor DO6, .31 break contacts 22;, fourth or bottom patching t jack, conductor 307, and the winding of relay 353 vw tohbattery. Relays3:0O: and 350 both operate over sa these circuits, and. at :make contacts 399 and: 351 close obvious cicuits to the release relays 32 and 368 which also operate and cause the channE selecting switches to release from their last op erated position. The release circuits are fror the ground, at the make contacts 321 and 368 through, break contacts 34.2 and 382, and th ciosed off-normal, springs of each switch to th respective release magnets. Upon the closure o these circuits, both minor switches release im mediately, and upon complete restoration to normal, open. their off-normal springs.

W~hen the dial is let go, pulsing relay 100 ir Figure 1 follows the interruptions of the impulse springs- . exactly: as, before, but with different results. The pulsing springs 103 of this relay, for examnple, are now without effect, since the local pulsing circuit to the vertical magnet c27 is now open at make contacts I13, and the circuit tothe rotary, magnet. 132 is likewise open at break o0 contacts-148. Pulsing springs 101 and 102 however, are now fully effective, and at eache interruption open the circuits of the energized pulsing oulse absorbing' relays 330 and' 3T both operate, fr-ngrouinds at the-make contacts 321 and 3Nai , trough break contacts 392 and 352. Relays 330 and: 37 at make contacts 32 and: 372 lock op0 emrted; and at make contacts 331 and 371 prepoare circuits for the pulse, absorbing relays 340 and 380. Upon the re-operation of relays 310 and 350 thearefore, at the end; of the: first impulse, ground i throigh make contacts 311 and 359 in addition to re-energizing relays 320 and 360 which being slow to release; remain operated during the pulsing, also passes through: make contacts 33f and J3a to the upper windings of relayys340 and 38Me which operate. These relays upon operating, at matke contacts 3.42, and 382 lock to the grounds atn make contacts, 321 and 36 , and at make contactsn 7,41 and 38: prepare the circuits of the rotary or stepping magnets, Upon each subsequent release of the relays 316-and 3,5. therefore; during the remainder of the pulses, the rotary magnets operate and step* the wipers across the banks. Since the first pulse has been absorbed to provide time for the release, as just described: the number of steps taken at this point will be one less than the digit dialled.

When the dial, reaches normal however, the shunt springs-open and relays 115 and 133 release. Relay I Mis of course again in the operated position at this time. Upon. the release of relay 130 make contacts 139 open and remove ground from pulsing contacts 1:611 and 102 and hence from relays 30: and13503 Relays 310' and 350 thereupon reease, and at break: make contacts 311 and 351 open the circuit of release relays 328 and 3860, and close circuits to the rotary magnets by way f closed'make contacts 341 and 38!. The rotary nagnets thereupon operate and advance the driers one additional step. Relays 323 and 36 hen release after a short delay due to their slow elease characteristics, and at make springs 32.1 nd 3 6lopen the locking circuits of the pulse aborbing relays which likewise restore and release he rotary magnets. Relays 320 and 300 also t hreaik contacts 322 and 323, and break contacts 62,and 363 close the wiper circuits to the selected uning elements, such as fixed condensers of arious values, in: the associated radio receiver ndý transmitter.

To. talk,. the operator at the control station 2,475,( 9 first operates the press to talk key 10. This disconnects the loud-speaker amplifier, and connects the telephone transmitter 13 directly across the line or talking conductors 30 and 31. This closes a direct current circuit over both conductors in series as follows: ground through the lower winding of the battery feed relay 115, lower winding of the differential relay 130, lower left hand winding of repeating coil 138, conductor 31, lower winding of the telephone induction coil, transmitter 13, make contacts of key 10, conductor 30, upper left winding of repeating coil 138, and the upper winding of relays 130 and I 15 to battery. Relay I15 operates over this circuit, but differential relay 13 does not, due to the fact that its windings are now energized in opposition. A circuit is therefore closed through make contacts (1 for the operation of the talklisten relay 240. This circuit is as follows: ground through break contacts 31, make contacts 11 6 2( both right hand windings of repeating coil 138 in parallel, make contacts 141 and 142, break contacts 181 and 152, switch wipers and bank contacts, conductors 208 and 201, both left hand windings in parallel of repeating coil 235, and 2 the winding of relay 240 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 con- 3 tacts 241 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 3Q0 and 305. Relay 240 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 1n and relay 240 as may be necessary, to listen to incoming speech.

To send Morse code, the operator plugs a telegraph key into the keying jack 18, 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 33. make springs 147A, wiper 108, bank contact 199, conductor 208, the lower patching jack and conductor 308 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 194.

When therefore, test wiper 193 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 fron the make contacts 211 on the busying relay 210 or from the busying key 238, will cause busy re lay 120 in the switch to operate, by way of th wiper 193, and make contacts 151 on the rotar: transfer relay. Relay 120 upon operating a make contacts 122 grounds the tone start lea (19, at make contacts 123 prepares a lockin circuit for itself, at break contacts 123 opens th operate circuit of switching relay 140, at mak contacts 124 prepares the automatic rotary cir cuit which is not required in this instance, an at break contacts 125 opens the regular pulsin circuit to the rotary magnet. Finally relay I at make contacts 121 connects busy tone to the line conductor 31 from conductor 128, by way of break contacts 156 and 143. This busy tone passes through the receiver 14 of the calling telephone where it is audible to the operator, and then through condenser 15, conductor 30 and the upper windings of relays 130 and 115 to battery and ground. The calling station must then hang up and try again later.

Control 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 214 into the patching jacks 215, make contacts 212 in the jack 215 will be closed, and itherefore the associated 0 lamp 213 will be lit, and the busying relay 210 will be operated. Relay 210, at its break-make contacts 211, will disconnect the upper winding of relay 230 from test conductor 203, 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 merely to remove the handset, thus operating relays (0, 105 and I 10, and set the quick select switch on its first contact. With the contact arms 27 and 28 on the first contacts, an alternating cur35 rent circuit is closed through both pairs of relays associated therewith, and all of these relays operate. Considering the upper pair of relays 400 and 410 for example, the positive half cycles of current, if they may be assumed to be moving 40 from left to right, will be opposed by rectifier disc 403 and must pass through the relay 400, but they will be shunted around relay 410 by the rectifier disc 413 which is poled in the opposite direction to disc 403. Similarly, the negative 45 half cycles of current will be opposed by disc 413 and thus forced through relay 410 but will be shunted around relay 400 by disc 403. Both relays will therefore operate over the circuit extending from ground at the first contact, through 50 contact arm 27, conductor 34, relays 400 and 410, and the secondary of the alternating current source transformer to ground. The operation of the lower pair is similar.

The quick select relays 400, 410, 420 and 430 55 upon operating, at their upper make contacts connect ground to conductor 495 and to cut-off relay 160 which operates. Relay 8I upon operating, at break contacts 161 and 162 opens the switch talking circuit to wipers 187 and 189, and ; 60 at break contacts 163 opens the dial tone circuit, 3 which was closed upon the operation of relay I 19.

The quick select relays also, at their make contacts 402, 412, 422 and 432 close direct current circuits to their dependent or slave relays 441, e 65 450, 480, 470 and 480. These latter relays are Y employed because of the fact that the heavy t spring loads involved would be too much for the d controlling alternating current relays 4~, to .41 g Relays 440, 450, 460, 470 and 480 upon operate 70 ing, complete a speech circuit from the calling :e control station direct to the selected radio unit - independently of the wipers of the stepping d switch associated with the said control station.

9g This circuit is from the control station telephone, 23 75 over conducts 30 and 31, through the left hand I 72,4 i1 windings of the repeating coil 138 and condenser 139, by induction to the right hand side of the repeating coil 138, conductors 493 and 494, make contacts 442 and 443, 451 and 453, 461 and 465, 471 and 481, conductors 496 and 497, patching jacks and cord, conductors 217 and 218, left hand Windings of repeating coil 235, by induction to the right hand windings of the repeating coil, break contacts 241 and 242, the upper patching jacks, and conductors 30M and 301 to the receiver output transformer 314. The channel selecting equipment is not affected, and pulsing relays 310 and 350 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 115 which operates and at the same time provides current for the telephone transmitter. Differential relay 130 remains unoperated as before and at break contacts 131 connects ground to the center point of repeating coil 138 by way of make 2 contacts 116. 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 2 receiver 313 to the transmitter 353. It can then be transferred back and forth by releasing 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 3 setting his quick select switch also on its first contacts. He cannot do so by dialing however.

Control station call to attendant Assuming a single attendant station, and as- 35 suming likewise that the intercommunicating telephone associated with this attendant station is connected to the first contacts of the tenth level in the line banks or speech banks of the control station switches, the control station may com- 40 municate with the attendant over this phone by removing the handset in the usual manner and dialing "01." Upon the removal of the handset and the closing of cradle switch contacts 16, relays 100, 105 45 and 110 operate in the manner already described, and on the dialing of the first digit, the vertical magnet 127 responds to the pulsations of contacts 103 and elevates the wipers to the tenth level. The normal post springs 149 will operate as 50 the wipers reach the tenth level but without effect. Transfer relay 110 then restores, and transfers the pulsing circuit to the rotary magnet 132. The rotary magnet therefore responds to the second digit in the usual manner, and steps 55 the wipers one step into the banks, of which there are six, or one for each wiper. Relays 150 and 155 operate as before, during the rotary stepping.

In this position line wipers 187 and 189 are connected to the left side of repeating coil 505 in Fig- 60 ure 5, by way of bank contacts 500 and 501 and conductors 503 and 504, while test wiper 193 is connected to negative battery by way of bank contact 502, conductor 506, and resistor 507. The t other wipers are now standing on contacts which 65 I are vacant, except perhaps for the bank multiple f from the corresponding contacts of the other l control switches. Relays 115 and 130 operate as t before each time the dial goes off normal and re- a store after each digit, without effect. 70 a If the attendant telephone is already in use, by r a call from another control station, test wiper 193 will encounter direct ground from the other o switch on the test contact on which it is standing, n which ground will pass immediately through 75 la 75,675 12 make contacts 157 to busy relay 120, which will thereupon operate and lock, cut off the switching relay, and connect busy tone to the calling line in the usual manner.

If the attendant telephone is idle however, test wiper 193 will encounter only negative battery through resistor 507 on the test contact. Busy relay 120 therefore will not operate, but when transfer relays 150 and 155 restore after the second digit, switching relay 140 operates from this same battery, by way of break contacts 157 and i23 to the ground at make contacts 106. Switching relay 140 upon operating, at make contacts 141 and 142 extends the talking circuit through 16 to the repeating coil 505, at break contacts 143 opens the busy tone circuit, at make contacts 146 connects direct ground to the test wiper, at make contacts 147 locks to ground from make contacts 107.

0 To signal the attendant, the control station operator will now close the press to talk switch momentarily. This will again complete a direct current loop circuit over conductors 30 and 31, through the transmitter 13 and make contacts 10, & for the operation of the battery feed relay 115.

Relay 130, being again energized opposing, does not operate, and ground from break contacts 131, passing through make contacts 116, causes the operation of signal buzzer 512 and the lighting of 0 signal lamp 513, by way of both right hand windings of repeating coil 138 in parallel, through contacts 141 and 142, 161 and 162, wipers 187 and 189, bank contacts 500 and 501, conductors 503 and 504, left hand windings of repeating coil 505 in parallel, and break contacts 511.

When the attendant answers, by removing the receiver or handset from the intercommunication telephone, not shown, a circuit is closed over conductors 514 and 515, through back contacts of the answering key 554 and the right hand windings of repeating coil to battery feed relay 510.

Relay 510 operates over this circuit to cut off 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 115 to his telephone transmitter.

To call the attendant station telephone of Fgure 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, relays 100, 105 and I10 will, operate in the usual way, and on the positioning of the quick select switch, contact arm 27 will encounter an open contact so that relays 400 and 410 will remain normal, but contact arm 28 will encounter negative pulsations of current through the rectifier 26, which will cause the operation of relay 430 and its associated relays 470 and 480. Relay 430 also at make contacts 431 will Pass ground to cut-off relay 160 which will accordingly operate o cut off the dial tone and disconnect wipers 187 and 189. The speech circuit now extends rom the right side of repeating coil 138 to the eft side of repeating coil 508, by way of conducors 493 and 494, break contacts 442 and 443, 452 nd 454, 464 and 468, make contacts 478 and 488, end conductors 498 and 4,99 to the left side of epeating coil 508.

To signal the attendant, the control station perator will operate the press to talk key moientarily as before, to operate battery feed rely 1 15 This again connects ground from break 2,475,67 13 ,ontacts 131 to the center point of the repeating fc *oil 138. This ground thereupon passes over both b ;ides of the just traced speech circuit in parallel ir ;o the center point of the repeating coil 508, and g ;hence through break contacts 551 to the buzzer 5 n 552 and the signal lamp 553. The buzzer buzzes rh and the lamp lights in response, as a signal to the a attendant, who answers by removing the handset t. and operating key 554 down. This causes the op- v eration of the battery feed relay 550 to cut off the 10 b signals, and completes the talking circuit be- e tween the two telephones as before. c In case a number of attendant station intercommunicating telephones are provided, they t will be connected to successive contacts in the 15 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 correspond- 20 ing "extra" test contact, corresponding to bank contact 197.

If now an operator at a control station dials "01" to call an attendant, and the first attendant telephone is idle, the operation is exactly as 25 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. o0 The action briefly is as follows.

When the control operator dials "0," after removing the handset and listening for dial tone, the vertical magnet 127 again raises the wipers of the switch to the tenth level, whereupon the E5 switch shaft again causes the operation of the normal post springs 149, thereby connecting wiper 196 to the open make contacts 124 on the busy relay, to prepare the automatic rotary operation. Now when the operator dials the sec- ,, ond digit "1," transfer relays 150 and 155 operate as before, and the rotary magnet 132 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 45 to the busy relay 120 by way of test wiper 193 and make contacts 157. The busy relay 120 will thereupon operate, will open the switching relay circuit, open the pulsing circuit to the rotary magnet, and prepare the automatic rotary cir- 5) cult, at make contacts 124. Thus, when transfer relay 150 restores, shortly after the cessation of the rotary pulsing, and before transfer relay 155 can release, a circuit is completed for the operation of the interrupter relay 165 as follows: ground from the test contact in the bank, through the strap connecting it to the associated extra test contact, wiper 196, make contacts of the normal post springs 149, make contacts 124, break contacts 151, make contacts 158, break 6 contacts 133, and the winding of relay 165 to battery.

Interrupter relay 165 upon operating over this circuit, at make contacts 166 locks to ground from make contacts 108, and at make contacts 167 closes an obvious circuit to the rotary magnet 132, which operates and steps the wipers on to the next contacts. A branch of this same circuit also passes through break contacts 153 to transfer relay 155 and prevents this relay from releasing. The operation of rotary magnet 132 opens break contacts 133, releasing relay 165.

Relay S 5 in turn, opens the circuit to the rotary magnet which releases, and to relay 155 which however being slow to release remains operated 14 Sr an instant. If the next bank contact is also usy, wiper 198 will still encounter ground, and iterrupter relay 165 will again operate, re-enerizing relay 155 and re-operating the rotary maget. If all of the attendant phones are busy, elay 165 and magnet 132 will continue to operte alternately in this manner at high speed unil the last contacts of the group are reached, Thich as previously stated, have no strapping etween the test and extra test contacts. The xtra test wiper 196 will therefore encounter an pen contact, and the stepping will stop. Test vi3ner 183 however, will still encounter ground, ,hus maintaining busy relay 120 operated, and when transfer relay 155 releases after a slight delay, the lower contacts of the break-make-beore-break springs 15' of this relay will complete , locking circuit for relay 120, by way of make springs 523 and 101. At the same time break contacts 158 close to complete the busy tone circuit.

If the last attendant phone or any intermediate phone is idle however, there will be only negative battery through a resistor such as 507 on its test contact. The rotary stepping will therefore stop at that point, and busy relay 120 will release. Transfer relay 155 will also release after the usual short delay, and switching relay 140 will immediately operate and lock and switch the talking circuit through to the wipers 187 and 189, 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 118 leading from the attendant station to the lower winding of the switching relay 140, and special wiring to the bank contacts associated with the pulsing and test wipers 191, 193 and 196, as indicated by the dotted conductors 204, 205 and 207, leading to bank contacts 192A, 194A and 197A.

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 I I8 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 0 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 187 and 189 will be 65 on bank contacts 188 and 190, wipers 191, 193 and 196 will be on bank contacts 192A, 194A and I9TA, and wiper 198 will be on bank contact M19.

If this unit is idle, battery through the winding of cutoff relay 220 and the lower winding of hold 70 relay 230 will be on test contact 194A. When therefore, transfer relays 150 and 155 release, shortly after the last rotary impulse, a circuit will be closed for switching relay 140 in series with relays 220 and 230 as follows: ground 7 through make contacts 109, break contacts 123, Upper winding 6f relay 1-40, upper break -contacts of ,,he .break-make.before -break springs 'i 5, .test wiper '93, test contact 194A, conductor '2.0., and the windings of relays 22D and -230 in parallel to negative battery. Relays .40, 220 and 230 all operate over'this.circuit.

.Switching relay 140 upon operating, at make contacts 141 and '42 switches the talking circuit through to bank contacts 088 and 1:9, at make contacts 144 extends the transmitter channel- 1 select -pulsing circuit through to wiper 196 and bank contact I9~A, and at make contacts 145 extends -the receiver channel-select pulsing circuit through-to wiper 10; and bank contact 192A.

Relay 140 -also ;at -make contacts 146 extends di- 1 redt ground to wiper i 93 and bank contact 194A.

The -other :functions of the switching relay are as 'explained in previous sections. Cutoff relay 220 upon operating, at make contacts 22 and 222 extends the -channel-select pulsing circuits 2 through to the pulsing conductors 302 and 307 and the associated pulsing relays 310 and 350.

Relay,220 also, at Ibreak contacts 221 and 222 disconnects conductors 202 :and 206 from these circuits. Hold relay :23 upon operating extends 2r holdinug.ground to the hold conductors 303 and 'S inthe usual manner.

When 'theatendant now dials the third digit, relays l',.and 1:3 operate from the shunt springs as fusual, as soon as the dial moves off normal, 3 and relay 7130 at gmake contacts 1:31 connects ground simultaneously to both. of the aforementioned channel-select :ulsing circuits to relays e10 and 350 Both of these relays thereupon operate immediately to release the channel select switches in the manner previously described.

When the dial is 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 i115 and 130 release as before, and relay I'30 again removes ground from make contacts.e 10 and t'02 andh ence from the channel-select pulsing circuits. Relays 310 and 350 and their associated relays then restore just as previously explained, and the minor switches advance one final step to compensate for the absorbed initial pulse. The talking circuit is switched from receiver to transmitter in the usual way by operatingthe talk-listsen relay 2'0 over the speech circuit.

If the called unit is already in use from ,another attendant station at the time this call is attempted, ground from the other switch will be on test contact 194A and as soon as test wiper 65 M93 lands on this contact busy relay C.20 wi!l operate and give the busy signal, and on. the release of transfer relay 1-55 will lock through the .lower ' break contacts of springs '57. The switching relay 140 is at the same time prevented from oper- f0 i] ating, by the open break contacts of the break- t make springs 123. If the second attendant ' wishes to cut in on the connection, he may do so o at any time, by operating his override button, a This connects ground to conductor .8H3 and to 65 i the lower winding of the .switching .relay .140 o: which operates and locks, cuts off the busy sig- it nal, and extends the speech and pulsing. circuits le to the busy unit. The second attendant may 01 either listen or talk on this connection, or both, 70 m and may if desired,, release and re-pocition the le minor switches of the said radio unit. The first T attendant may of course, ,do likewise. < If the called unit is in use -by a regular. control m station, it will be busy to other control stations, -75 m -16 but not 'to the:attendant stations, ,becauseof ithi fact that a busying ground on bank contact jilis notC:ommunicatedtoabank:contact -l94Adin th. attendant's switch. Forithis reason the attend. ant's switch would cut through immediately or such ;a rcall, from the battery on conductor 2,05 and the use of the override button -would not -bt required. Cutoff relay 220 would operate to xtend the pulsing circuits from 3the attendant 0 switch, andcut 'off the pulsingecircuits from the control switch. The attendant station may now release and reset the ,channel select :switches of -the -elected unit without interference from the controlistation.

5 If the attendant ,wishes to make :a radio call through a unit of the second group, the 'operation is similar. Busying relay 24j0 of the called unit -will be operated to ground the associated test contact, such 'as i,94, .but this will not affect 0 thecorresponding testcontact in the bank of the attendant's switch. ;For this 'reason, -when ,an attendant station calls such a unit, it is again sWitched through immediately, and may if desired ,change the channel -setting .of 'such urnit Sat will merely by 'dialing the.required-third :digit.

Alternative pulsing scheme When the alternative pulsing scheme of Figure 5 .is.used, the gPulsing nrelays of the receiver and ,transitterchannel selectiing equipment.are mul tipled together as indicated in Figure 5-and connected to-the upper pulsing conductor assooiated with the receiver, the ;lower pulsing -conductor being connected to greound 'at the transmitter channelselecting equipment.

Now when a -selector swvitch -extends a connection .to this channel selecting eqtuipment and the operation of the swietching .relay 1 40 following -the dialing -of .the second 'digit, .immediately causes the operation of the pulsing, relays 520 and 50.

Tfhe circuit .for these r-elays is as .follows: ground from the radio :transmitter .on conductor 1, tShe before break springs 22-22 conduetor 206, sbank contact 97,r s wiper 1 as, break contacts of the normal post springs, 1 49, makecontacts, .144,-.make contacts I. .and .-a, Mnake contacts 144, wip er .19 1, bank -contact .92, conductor -202, breakcontacts .of the make before break ýsprings 22L,, through the secondpatchin.g jacks,. conductor i362, and .the windings of relays -520 ,and 4560 in lrallel.

Pulsing relays 52.0 and -560 upon operatig, close ý obvious circuits to ,release relays 30 ,and VI.M which also operate, to .open the release -cirTuits and prepare the stepping circuits. ,Now vhen the channel selecting digit .is dialled, each elease. of pulsing relay 1-9-causes a correspondng release of pulsig relays 5:2 and 560, through he interruptions of make, contacts 101 and ,10,2.. hie slow release wiper-guard relays 540 and -580 'perate on -the first Pulse and 'release shortly fter the last pulse to -keep the wipers :open durng .the stepping. The rotary .m-agnet :opera-tes n the first pulse ýard on each successive pulse, Sarallel w-ith the wiper guard -relays. The r rease relays -being also slow to release are not ,twardly, affected by the pulsing. At the terination, of the call, -when the connection is reased, pulsing relays 52 and '560 also relealse. he -release relays, due to their slow release ualities, :remrain operated for an instant, peritting the wiper guard .relays and the 'rotary agnets to be again:momenitarily, 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 utilized 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 first and a second control station, a first and a second selector switch associated respectively with said control stations in the order named, a plurality 2 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, means in said first selector switch to extend the associated pulse repeating circuit to such selected unit if it is free and to prevent such extension if said 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.

2. In a switching system, a first and a second control station, a first and a second selector switch associated respectively with said 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 plse repeating circuit in each said selector switch, a speech circuit from each said control station to its associated 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, means in said first selector switch to then extend the associated speech and pulse repeating circuits to such selected unit only if it is not in use, means in said second selecter to extend the associated speech and pulse repeating circuits to such selected unit regardless of its condition of use, means to repeat further impulses from said impulsing devices over said extended pulse repeating circuits to the channel selecting devices of such selected units 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 first selecto switch to prevent interference.

3. In a switching system, a control station, control selector associated therewith, an attend ant station, an attendant selector associated therewith, a plurality of multi-channel radi units, a radio receiver and a radio transmitter ii each said unit, channel selecting devices asso ciated with each said unit, a speech circuit an a pulse repeating circuit associated with each sai selector, an impulsing device at.said control sta tion for operating the associated selector to selec 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 said extended pulse repeating circuits to operate the channel selecting devices of the selected unit, and means responsive to the selection 0 of the attendant station by said control switch to extend the associated speech circuit to said attendant station if idle, for purposes of intercommunication.

4. In a radio switching system, a control sta!5 tion, 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 station, a plurality of multi-channel radio units accessible to any of said switches, a radio receiver and a radio transmitter in each said unit, channel selecting devices associated with each said unit, a speech circuit and a pulse repeating circuit in each said switch, an impulsing device at said 35 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 selection of an idle one of said radio units by said con40 trol switch to extend the associated speech 'and pulse repeating circuits to said idle unit, an impulsing device at each of said attendant stations for transmitting impulses to the associated two motion switch to cause said switch to select any 4one of said radio units, means responsive to the selection of any one of said units by said attendant switch to extend the associated speech and pulse repeating circuits to said selected unit even if said selected unit is busy, means to repeat fur,O ther impulses from said impulsing devices over such last mentioned extended pulse repeating circuit to the channel selecting devices of such selected unit for operating and positioning said. last named devices, means responsive to the selec55 tion of an idle attendant station by said control switch to extend the associated speech circuit to said idle attendant station, means responsive to the selection of a busy attendant station by said control switch to cause said switch to rotate auto60 matically in search of an idle attendant station, Sand means to stop said rotation and give a busy signal to the calling station in case all of said attendant stations are busy.

r 5. In a radio telephone switching system, a first 5 control station, a first stepping switch associated 5 therewith, a second control station, a second stepping switch associated therewith, a first group of d radio units, a second group of radio units, a radio o receiver and a radio transmitter in each of said n 70 units, a speech circuit extending from each said S control station to its associated stepping switch, d impulsing means at said first control station to d operate said first stepping switch to select any - one of said radio, units,, means to thereupon ext 75 tend the associated speech circuit to the receiver, it ofsaid selected unit only in case saidselected: unit is in the first group:andis -idle, impulsing means at said second control station. for operating said second stepping switch -to-select anyone:of said radio units, means to thereupon extend the associated speech circuit to the-receiver of said selected unit regardless of. the group involved and regardless of the condition .of. use of said selected unit, a relay associatedwith each said unit, and means for operating, such relay at will from the calling control stationý over such extended speech circuit, to transfer the extended speech circuit from the receiver to the transmitter of the selected unit.

6. In a radio switching system, a first control station, a second,:control station, a first and a second two-motion selector .switch associated respectivelywith.said, stations, a..first and a second group, of radio units,. a radio receiver and a radio transmitter in each of saidunits; a: pulsing circuit, a speech: circuit and. a telegraph circuit extending from eachsaid controlstation to its associated selector switch; impulsing means at each said station for :operatingu the associated switch over the associated -pulsing,acircuit to select any one.of.said radio units;lmeans responsive to such selectionby said first selector switch to extend the:.associated; speech.,circuit .to, the receiver of the selected unit, andý,the:; associated telegraph circuit: to. the; transmitter thereof provided such selected,unit is.both in thefirst group andis idle, means responsive to such:selection by said second selector ofor extending the associated speech circuit to the receiver and the associated telegraph circuit to the transmitter -of the selected unit regardless of the group. involved and regardless of thebusy condition of:such:selected unit, a relay associated -witheachsaid.unit; :a circuit means controlled from the calling, control station over the.extended. speech: circuit for operating said relay.to transfer said: extended,.speech circuit to 4o the,.transmitter. of the selected-unit and to condition .said: transmitter .forthe transmission of speech,:and, control means atsaid, stations to permit the subsequent release,,and, re-operation of 45 saidgrelay over saidcircuit means as required duringithe :connectionm: 7. In a radio switching :system, a control station, a:selector,;switch;,.wipers,,on said switch, a speech circuit and.a pulsingcircuit extending be-, 0o tween said. controlstationand said switch, a first group ofs radio units 'accessible tosaid wipers, a second groupof radio unitsalsoýaccessible to said Wipers but made ýartificiallybusy,.thereto, -an imr pulsing device.at said. control station for operat- 55 ing said switch over said pulsing circuit to select any-one of said units, means responsive only to; the selection of an .idle unit in. said first group to.-extend said -speech, circuit, through 'the wipers of:,said switch to such selected unit, a radio receiver and a radio transmitter in each said unit60 s means controllable over said speech circuit for s switching said speech circuit ,backand forth be- t tween the receiver and transmitter of said se- c lected unit as required forw radio communication, B& s a quick select hand operated switch at said con- a trol station, quick select relays for said last men- o tioned switch; and means controlled by said quick c. select switch for operating said;relays in various st combinations to extend said-speech circuit direct 0, u: to any one of said units in said second group, in- s5 dependently of the wipers of, said selector switch, m 8.tIn a radio switching -system, a control sta-- ci tion, a selector switch? wipers on said switch, a sa speech circuit' and a -pulsing circuit extending 75. sa between said control statioi::and: said. selector switch a first group of radio unitsýaccessible to the wipers of said selector switch, a second group of radio units also accessible to said -wipers but made artificially busy.thereto, an-impulsing device at said control station- for operating said switch over said pulsing circuit to select any one of said units, means responsive only to the selectiohnof an idle unit in said first group by said wipers to extend said speech circuit through said wipers to such selected unit, a multi-point .hand operated switch at said control station, means controlled by positioning said multi-point switch for extending said speech circuit from said control station direct to any one of said units in said second group independently, of said wipers, a radio receiver and a radio transmitter in each radio unit, means controllable from said control station over either of said extended speech cir0 cuits for switching said speech circuit back and forth between the receiver and transmitter of the unit involved, and a cross connecting arrangement for quickly transferring any of the units of said second group to said first group and remov5 ing the busy condition therefrom.

9. In a remote control system, a first control, station, a second- control station,' a first selector switch associated with said first station, a second selector switch associated with said second 0 station, a speech circuit and a pulsing circuit extending between each said control station and its associated selector switch, wipers on each said selector switch, a first and a second group of radio transmitter-receiver units, an- impulsing device at each said control station for operating the associated selector switch over the associated pulsing circuit to select any one of said 'transmitterreceiver units, means in said first switch responsive only to the selection thereby of an idle unit in said first group..to extend the associated speech, circuit through the wipers of said firstswitch to such selected unit, means in said second. switch responsive to the selection thereby of any unit in either .of said groups to.extend the associated speech circuit through the wipers of said second switch to such selected unit even if busy, a quick select circui i it for said first selector switch, a manually operated multi-point contact switch at said first control station for operatingsaid quick select circuit, to extend the speech circuit of said.first control station toany unit of said second group independently of the wipers of said first selector switch, andt means in said first selector switch to extend the speech circuit of said.. first control station, to said second control station, either through the wipers of said first switchf or through said quick select circuit... 10. In a remote ,control system, a .first control. tation, a second- control station, a first: stepping; .witch associated,with said:first.station, asecond. tepping switch, associated with. said, second staion, a speech :circuit ,associated.with, each said ontrol station,: wipers- on each -.said stepping, witch, a first and a:second group,of radio units,, .-radio, receiver: and- a radio, transmitter in "each f .saidiunits,.:an.;impulsing..deice.;at- each said, ontrol .station,- for :operating the -associated-, ;epping; switch, to-seleot any.-one' of said radio, nits,,: means .in:, said, first -steppingswitch :.-rePonsive ionrly.to .the selection -thereby ofian idle:, nit in said first.group ,to'extend the speech ,ciritVof: said first, station through the. wipers :of id first .switch toe.suclh'selected;,, t,,means in-id:second::switch:.,responsive to the;'selectioV2,475,6 21 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 first switch, a manually operated multi-point contact switch at said first control station for operating said relay circuit to select any radio unit in said second group and extend the speech circuit of 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 receiver and 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 2( 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 stations, a second group of control sta- 2 tions, a selector switch and a speech circuit associated with each of said control stations, wipers on said switches, a first group of radio transmitter and receiver units, a second group of radio transmitter and receiver units, impulse responsive 3 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 first group of units but not to a unit in said second group of units, impulse responsive means for extending the speech circuit of any one of said second group of stations through the wipers of 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 stations, 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.

12. In a 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 relay for repeating further impulses from said impulse dial over both of said pulse repeating circuits simultaneously, and means for energizing such circuits during such further pulsing only while said dia is off normal.

13. In a remote control system, a first and second radio transmitter and receiver unit, ai impulse dial, a two motion selector switch, a puls ing relay in said switch operated in response t impulses from said dial to cause said selecto switch to seize either of said transmitter an receiver units depending on the number dialled, pulse repeating circuit comprising two conductor 22 extended to either of said transmitter and receiver units in response to the seizure 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 to cause such further impulses to be repeated by 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 0 of said second transmitter and receiver unit by said selector switch.

14. In a remote control system, a plurality of control stations, a two-motion selector switch associated with each said control station; an impulsing 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 0 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 35 said impulsing circuit to select any one of said multi-channel units, means to 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 40 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. 45 15. In a radio switching system, 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 each of said stations and its 50 associated switch, an impulsing 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 asso55 ciated 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 60 responsive to the selection of a free unit by an operated control switch to extend the associated talking and pulse repeating circuits to said free Sunit, means for repeating further impulses from the impulsing device at the associated control s 05 station over said extended pulse repeating cirs cuit to the channel selecting switches of said selected unit to position said switches, means rea sponsive to the selection of a busy unit by said a operated control switch for preventing such ex- 70 tension of said talking and pulse repeating ciro cuits and for giving a busy signal to the calling ,r control station, means responsive to the selecd tion of any one of said units by an operated ata tendant switch to extend the associated talking s 75 and pulse repeating circuits to such selected unit 23' Whether free Or not, .means, for repeatingu further impulses from the impulsing, device, atr: the associated attendant station- over said extended Pulse repeating circuit -to the channel selecting switches of said: selected: unit to- position said switches,: and means whereby any one of said control switches may be: operated by its. associated, impulsing device to ;extend the: associated talking circuit from. the associated, control: station to said attendant:station: 16. In a. remote control system a control station, a, plurality, of radio units, a radio transmitter and a radio receiver in each of said units, aopair of relays connectedin series, a second pair of relays connected in series, a rectifier disc connected, in shunt with each of said relays, the, rectifier discs of each pair of relays being also connected in series with each other. but poled oppositely with respect to each other, ,an alternating current source connected toleach pair of relays, a multi-point hand operated switch having different positions for operating said relays, in different combinations from said alternating current source to select any one of said radio units, a speech circuit, means, operated by such, operated relay combination for extending. said speech circuit from said control station to such selected radio unit, and means controlled over said extended speech' circuit for switching said speech circuit back and forth at will between the receiver 3 and transmitter of said selected unit .as required for two way, radio, communication.

17. In a remote control system, a Plurality; of radio units for two way radio communication, a control station, a speech circuit associated, with 3 said control station, a. pair of relays connected in series, a rectifier disc connected, in shunt with each of said relays andý poled, oppositely with respect to each other, another pair of relays arranged similarly, an alternating, current source; 4 terminals:for said source, connections from one of said terminals to one sidel of each, of said pairs of series relays, a hand. operated switch at said control station having a. plurality of positions, contact arms on.said switch connected individual- 45 ly to the other side of each of said pairs of relays; other rectifier discs, a plurality of contacts for each of said contact arms; some of said con, tacts being connected to the other terminal of said source directly, some of. said contacts being connected to said other terminal through differently 50 poled, ones of said other rectifier discs, and others of said, contacts being left, open, said contact: connections being made in:such a way: that for eacli Position of said switch- various of: said, relays are operated: in- different combinations;: and: means controlled by said operated combinations of relays for: extending: said, speech circuit from said control station to any desired -one of, said radio units asdetermined by the setting of said switch contact. arms on said contacts.

18. In a remote control system, a radio transr mitter and a radio receiver, impulse responsive relays and stepping switches, associated with said transmitter and receiver, a control station, an impulse dial at: said control station, a two motion selector switch; operated in response to preliminary trains of impulses from said dial to seize said: transmitter and receiver and the associated impulse responsive relays, pulse repeating circuits, extended to. said impulse responsive relays in responsive to the seizure thereof by said two >0 motion switch, a pulsing relay' for said. switch, special pulse repeating contacts on said relay for repeating- subsequent impulses to said impulse responsive relays over said extended pulse repeating circuits for operating and Positioning said 5 stepping switchese which remain at the set position upon release of the connection, means for energizing said pulse repeating circuits when said dial is moved off normal to initiate such further impulses, said stepping switches being released 0 from. their Previously operated position responsive to such energization, the first of such further impulses being absorbed, by said impulse responsive relays to increase the time available for such release, and means for de-energizing said pulse 5 repeating, circuits when said dial again reaches normal for causing said impulse responsive relays to pass an additional impulse to said stepping switches.

EDWARD S. PETERSON. REFERENCES CITED The following referenaces are of record in the file of- this: patent: Number 1572,756 1,619,228 2,061,699 2,101,668 2,176;868 2,206,231.

2;265,056 JNITED STATES PATENTS Name Date Smythe------------Feb 9 1926 Williams .--..---. . Mar. 1, 1927 BFo -------------- Nov. 24, 1936 Bishoposwan------------- Dec. 7, 1937 Boswan ------------ Oct. 24, 1939 MacKay Bowers ----------- July 2, 1940 ------------- Dec. 2, 1941