US2206231A

US2206231A - Communicating system

Info

Publication number: US2206231A
Application number: US169067A
Authority: US
Inventors: John R Mackay
Original assignee: Wallace and Tiernan Inc
Current assignee: US Filter Wallace and Tiernan Inc
Priority date: 1937-10-14
Filing date: 1937-10-14
Publication date: 1940-07-02
Anticipated expiration: 1957-07-02

Description

July 2, 1940. J, R, MacKAY COMMUNICATING SYSTEM Original Filed March 19, 1935 NNsN .n En.

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Patented July 2, 1940 coMMUNrcATING SYSTEM John R. MacKay, West Caldwell, N. J., assignor to Wallace` & Tiernan Products, Inc., Belleville, N. J., a corporation of New Jersey Application March 19, 1935, Serial No. 11,783,

which is a division of application Serial No. 730,127,` June 11, 1934. Dividedand this application October 14, 1937, Serial No. 169,067

14 claims. (ci. 25o-6) This invention relates to communicating systems. More particularly it relates to telephone systems and from a still morespeciiic aspect it relates to radio `telephone systems. This applione of a plurality of stations, andin accordance withthe system any of the stations can selectively call any desired one of the'other stations.

In the arrangement shown, only one carrier fre- `quency is employed for the `entire system for all purposes. For convenience, therefore, theseveral stations Will be identified as stationsA/B, C, etc., and in the following description the drawing will be taken to represent each of the stafcarrier which has similarly imposed` onvrit' a two-fold modulation.` It mayalsorbe explainedA .that `each vstation is provided with :selective relay `-means responsive to thereceptionof callingor `reply-calling carriers which are modulatedand `cation is a division of my copending application, tions in turn, aswill be explained." l Serial No. 11,783, filed March 19, 1935, for Com- `Each station of the system includes radioi re-"V municating system, whichwas itself a division ceiving apparatus and radio transmitting appa- 0f my copending application, Serial No. 730,127, ratus. The receiving apparatus is adaptedto `filed June 11, 1934, for` Communicating system. receive radio telephone signals and convert them i l0 One of the objects of the invention is t0 proto soundfrequency speech-representingcurrents, i0 vide a two-way radio telephone system in which and the `transmitting apparatus is adapted to `the user at the calling station operates a `call` have its filament and plate supply Vren'c`iered`4oper-l switch and the user at the called station receives ative upon energization of a transmitter control a signal, as the ringing of a bell, thereupon lifts relay so as to emit a desired carrier frequency r 15 his telephone receiver from its hook, and thereand also properly to modulate it when telephone m by the user at the calling station` is `given a sigconversation takes place in the manner later to be nal, as by means of a bell, indicating that his call described. `The receiving apparatus is also has been put through, and the user at the calladapted to receive modulated calling signals, and ing station thereupon removes his telephone the transmitting apparatus is ,alsoI adapted `to receiver from its hook, and two-way telephone transmit such signals, as more particularly ex- 20 conversation may then proceedas in the case of plained hereinafter. It will be understood Athat an ordinary communication over two land 1ine` it is immaterial whatfparticular type "of radio telephones which have been properlyconnected.` receiving apparatus and `radio transmitting ap- A further object ofthe invention isto provide paratus are employed with the system `and` ciri a radio telephone systemin `which the major cuits shown; it will be understood, by those fa- 25 portion of the apparatus employed islnot enermiliar with the art, thatthere are many4 types of gized` at all times but only periodically at such receiving and transmitting apparatus suitable for desired intervalsas will conserve the energy rethe purposes explained and` readily adapted for `quired to energize or activate such apparatus. use with the apparatus hereinafter more fully Further objects are to provide new combinadescribed. The receiving and transmitting ap- 30,

tions of instrumentalities and new sub-combinaparatus are therefore notshown inthedrawing.

tions thereof whereby the communication `sys- Each station includes an intermittently` ,opertern is comparatively inexpensive `to build and ating or cycling mechanism having for one puroperate, 'comparatively` simple in operation from pose the conservation of apparatus and of energy the standpoint of the intelligence requiredto required.` For thatand other purposes as here- -35 use it, and thoroughly reliable `inits operation.y inafter explained, a motor 923 is provided for Other objects and advantages will appear as a continuously rotating certain cams 9&3, llllll, and preferred form of the invention is hereinafter H02. While` this motor may assumea varietyof disclosed. i different forms; I prefer at present to employ a 40 The drawing illustrates an embodiment of motor ofthe magnetic type,su`ch as that described "'40 what is considered to be a preferred form of fthe and claimed in United States Patent No. 1,985,357 invention, and shows a wiring diagram of appa- `for Electric motor apparatus,v granted December ratus and connections at one of a number oi' sta- 25, 1934, upon` the application of `Charles F.

tions` between any two of which radiotelephone Wallace. i communication is to be established and main- 4The system is such that eac-h station isadapted 45 tained. Except forcertain features as will hereto transmit a carrier, for calling purposes; which inafter appear, `the apparatus and connections may be modulated both' by a buzzer modulating used at each of the various stations of this sysdevice, for `example,` andfalso by a circuit intertemis identical to that used at any of the other rupter. Upon receiving a call from another stastations; the system shownrepresents, as stated, tion, each station is adapted to .transmit a reply Y ner described.

It will be understood that for the purpose of conserving energy and the life of the apparatus, the radio receiving and transmitting apparatus (not shown) are normally .de-energized,-i. e., filament or heatercurrent being not supplied to the vacuum tubes thereof-except as hereinafter described.

Each station is provided with a motor-driven circuit interrupter 929 which is coded in `common to all of the stations and which has for one purpose to eliminate the effect of interference by sustained or otherwise interfering signals, prolonged static, etc. Here it may be stated that this 4common circuit interrupter 929 is not in circuit when any of the other code interrupters employed in the system is in circuit.

The receiving apparatus at each station emv bodies two selective relays |992 and |993. One of these relays, |993, is common to thecode of all stations of the system and is responsive to the coding imparted by any of the circuit interrupters 929, and the other of the selective relays, |992, is responsive to the particular code corresponding to that station and by which it is selectively called. Furthermore, the Wallace motor 923 at each station operates continuously, i. e., its circuit is never interrupted, and it not only periodically energizes the radio receiving apparatus at its station in the manner described in my above-mentioned copending applications, but also periodically interrupts transmission from that station and renders the radio receiving apparatus at that station operative during the intervals during which the transmission is interrupted; the purpose of this being to enable a Calling station to receive the return signal transmitted from the called station.

The circuit of the Wallace motor is as follows: vfrom the positive side of the 'l1/2 volt battery, through the conductors 92 I, 922, through the winding 923 of the Wallace motor, through the automatically operating` switch 924 forming a part of the Wallace motor, through the

conductors

925, 926, and 921 back to the negative side of the 71/2 volt battery. The cam switch 928 operated by the Wallace motor periodically closes the cirel cuit of therelay 929 as follows: from the positive side of the '7l/2 volt battery, through the conductor 939, through the relay 929, through the conductor 93|, through the cam operated switch Y 928, through the

conductors

932, 933, 9,21 back to the negative sideof the 71/2 volt battery.

Energization of the relay 929 energizes the lila- `ments of the tube 934 and the tubes of the radio sumption that the` drawing represents station A and that the user at thatstation desires to call- `one of the otherA stations, say station B.

The user at station A throws his callswitch 949 to` calling position thereby energizing the relay 94| in the following circuit: from the positive side of the 71/ volt battery, through vthe con'` ductor V92|:, through the contacts 9420i switch 949, through the conductor 943, through the relay 94|, through the

conductors

933 and 921, back to the negative side of the 'l1/2 volt battery. Energization of the relay 94| causes energization of the motor 944 in the following circuit: from the positive side of the '1l/2 volt battery, through the conductor 92|, through the motor 944, through the conductors 945, 949, through the contacts 941 (now closed) of hook switch |926, through the contacts 948 (now closed) of relay 94|, through the

conductors

933, 921, back to the negative side of the 7% volt battery.

` Energization of the relay 94| closes the primary circuit of the buzzer modulating device 949 as follows: fromfthe positive side of the '1%2 volt battery, through the conductor 92|, through the primary of the buzzer modulating device 999,l through the conductor 949, through the contacts 94? (now closed) of hook switch |929, through the contacts 949 (now closed) of relay 94|, through the

conductors

933, 921 back to the negative side of the 7 1/2 volt battery.

Energization, of the relay 94| also closes the secondary circuit of the buzzer modulating device 949 as4 follows: from the positive side of the Vmicrophone battery, through the conductor 959,

through the secondary of the buzzer modulating device 949, through the conductor 95|, through the contacts 999 (now closed) of the relay 94|, through the conductor 99|, through the contacts 992 l(now closed) of hook switch i929, through the conductors 963, 964, through the contacts 995 of the call switch 949, through the circuit interrupting device 969, through the conductor 991 to one side of the microphone input, whose other side is connected through the conductor 998 and ley-pass condenser |998 to the positive side of the microphone battery. I

Energizaton of the relay 94| closes its contacts IIIcso as to render the relay |993 energized independently of the action of the relay I993 after the initial call back signal has been received from station B, the circuit being as follows: from the positive side of the 'l1/2 volt battery, through the conductors 92|, 922, iII2, through the contacts I |98 (now closed) of the hook switch |926, through the conductor I I IB, through the contacts III' (now closed) of the relay 94E, through the conductors III'I, 492|, through the contacts |929.

(now open) of the relay |915, through the conductor I I I3, through the relay H193, through the

'conductors

929, 921 back to the negative side of the 7l/2 volt battery.

Energization of the relay 94| causes energization of the relay 919 in the following circuit:

.from the positive side of the 'l1/2 volt battery,

through the conductor 92 I, through the relay 919, through thev conductors 91I, 912, through the contacts 999 (now closed) of relay 94|, through the

conductors

933, 921, back to the negative side of the'll volt battery.

llnergization` of the relay 919 causes energization of the relay 929 in the following circuit: from the positive side ofthe 7% volt battery, through the conductors 92|, 939, through the relay 929, through the conductors 93|, 913, through the Ycontacts 914 Know closed) of relay 919, throughthe conductor 921 back to the negative side of the "I1/2 volt battery.

-Energization of the-relay 919 energizes the `transmitter control relay in the following circuit:

fromv thepositive side of the 'l1/2 volt battery, through the conductor 92 I, through the contacts 915 (now closed)` of relay 91,9, through the conductor 916, through the transmitter control res s 2,206,231 lay, `through the conductor ,911, to the negative side `of the l1/volt battery.

` tion of the relay 918 in the following circuit;

from the` positive` side of the '1l/2 volt battery,

`through the conductors 92|, 939, 919, through the relay `918;` through the conductors 989-, 946, `throughthe contacts 941 (now closed) of hook switch |026, through the contacts 948 (now closed) of the relay 94|, through the

conductors

933, 921, back to the negative side of the 'l1/2 volt battery."

Energization of the relay 918 causes its contacts |919 to open and thereby to cut out a key 98| hereinafter described. Energization of the relay 918 causes its contacts 982 to close and to establish automatic control, by the additional cam 983, yof the transmitting and reception periods in View of the fact that a single carrier frequency is employed for both transmission and reception. The cam 983 which is continuously rotated by the Wallacemotor has a plurality of high spots,*with intervening low spots of greater angular extent. Each of the high spots ofthis cani 983` causes the contacts 984 to be opened to deenergize the relay 931 whose circuit is as "follows: from the positive side of the r11/2 volt battery,fthrough` the conductors 92|, 930, through therelay 931, through the conductor 9,85, through thecontacts 984 (open when the high. spot `of the cam 983 is operative), through the conductor H09, through the contacts ||9| (now closed) of the hook switch |026, through the conductor 986, through the contacts 982 (now closed) of therelay 918, throughthe conductor 981, through the contacts 988 (now closed) of` the relay 919, through the conductor921, back to the negative side of the 71/2` volt battery. When the contacts 984` are closed, i. eL, when the low spots of the cam 983 are opposite the cam operated switch, the relay 931 is energized so that the plate or B battery supply is disconnectedfrom the radio receiver and `from the tube 934.

When the highspots of the cam 983 are opposite the camoperated switch, the radio trans- `mitting apparatus is rendered inoperative, or its operation suspended, by energization of the relay 999 in the following circuit: frornthe` positive side of the r11/2 volt battery, through the conductor 92|, through the relay 999, through the conductor 99|, through the contacts 992 (closed whenever a high spot of cam 983 is opposite the caml operated switch), through the conductor H90, through the contacts ||9| `(now closed) ofthe hook switch |926, through the conductor 986, through the contacts 982 (now closed) of relay 918, through the conductor 981, through the contacts"989 (now closed) of` relay "919,

. through the conductor` 921, back to the negative negative high voltage `lead to the radio transp mitter, thus preventing emission of a carrier.`

. Energization of the relay 94| causes its con-` tacts |909 to open and its contacts |09| to close,`

`to break the circuit of the relay |002 and `to establisha circuit through the relay |903. The

through the contacts 936 of relay 931, through the conductor 955, to the positive side of the plate supply or B battery. The circuit of the relay |003 is as follows: from the plate of the tube 934, through the conductor |994, through the contacts |99| (now closed) of the relay 94|, through the conductor |996, through the relay |903, through the; conductor 938, through the contacts 936 of the relay 931, through the conductor955, to the positive side oi the B battery.

The time interval of energization of the cntrol relay 999 by each high spot of the cam 983 is shorter than the time interval of operation of the` cam switch 928 by the high spot of the cam` |901. The purpose of this is to guard against the receiver at a desired called station being inoperative co-incidentally with the interval during which the transmitter at the calling station is inoperative.

By the operations thus far described at stationlA, i. e., the calling station, there is being "represen-ts that station.

The coded modulated carrier transmitted from station A is received at station B when the high spot of the cam `|901 at station B is opposite the cam-operated switch 928. It will be recalled that the cam-operated switch 928, when closed, causes `energization of` the relay 929 to cause the lilaments ofthe radio receiving apparatus and the filament of the tube 934 to be energized. When the coded modulated carrier is so received at station B, the increase of plate current of the tube 934 at station B causes `the selective relay |992 at station B to "be energized. This last mentioned relay at station B is one that is mechanically tuned to respond to the code imparted bythe circuit interrupter 966 atthe calling station.

, When the relay |992 at station B is energized `it closes its contacts |099 to establish the following circuit through the relay |998; from the positive side of the 71/2 volt battery, through the conductor 939, through the contacts |909 (now closed) of 4relay |992, through the conductor i9 i9, through the relay |098,` through the conductor battery. Energization of the relay |998 causes its contacts |0|| to close to energize the relay |9|5 in the following circuit: from the `positive side ofthe 'l1/2` volt battery, through the conductor 930, through the contacts |9|| (now closed) of` the relay |098, through the conductor` |9|6`, through the relay |9|5, through the conductors 926 921, back to the negative side of the 1l/2 volt battery.

Energization ofthe relay |9|5 causes all of its sets of contacts to Yclose and the closure of the contacts |9|8 establishes the following circuit `through the relay 929; from the positive side of the 'l1/2 volt `batte,ry,through the conductor 930, through the relay 929,`through the contacts |0|8 (now closed) of theA relay |915, through the con- `'i5 926, back to the negative side of the l'1l/2

volt i ductors

926, 921, back to the negative side of the 'Z1/2 volt battery.

The relay |008 is a slow release relay, that is, when it has been energized and has closed its contacts, the contacts will be maintained closed, even when the relay |002 or the vrelay |000 is deenergized, for an interval of time somewhat longer than that during which transmission is periodically interrupted at the calling station by the high spots of thecam 983 at that station, but the interval during which the relay |0108 so maintains its contacts closed is shorter than the high spot intervals ofthe cam H02, as will hereinafter be described. By virtue of this provision, solong as the transmission from .the calling station is taking place, notwithstanding that there are comparatively short interruptions of such transmission, the relay |098 at station B will maintain its contacts closed, even during the short intervals when the transmission from station A is being periodically interrupted. Closure of thecontacts |0|| of, the relay |003 causes continued energization of the relay |015. Maintained closure of the contacts |0i0 of the relay |015 causes energization of the relay 929 to be lmaintained and thereby the filaments of the radio receiving apparatus at station B and the filaments of the tube 930 at that station are maintained energized at this time independently of any operation of the cam |001 at station B.

Upon the above described energization of the relay |000 at station B the bell |0|2 at that station is caused to ring by virtue of its energization in the following circuit: from the positive side of the l1/2 volt battery, through the conductor 900, through the contacts |0|| (now closed) of lthe relay |008, through the bell |0|2, through the conductor I0 |3, through the contacts |0|9 (now closed) of hook switch |026, through the

conductors

933, 921, back to the negative side .of the '7l/2 volt battery.

When the user at station B hears his 4bell |0|2 he removes his head piece |025 from the hook of the hook switch |026. This removal of the head piece from the hook of the hook switch causes the contacts |0|4 to be automatically opened whereby the circuit of the bell I0 |2 is broken and the bell stops ringing. Removal of the head piece |029 from the hookvof the hook switch causes the contacts |021 to be automatically closed establishing the following energizing cir` cuit through the relay 910: from the positive side of the 7 1/2 volt battery, through the conductor 92|, through the relay 910, through the conductor 91|, through the contacts |021 (now' closed) of the hook switch |026, through the conductors` 933, 921, back to the negative side of the '7l/2 volt battery.

Energization of the relay 910 causes all of its contacts to close and closure of the contacts 915 causes the transmitter control relay to be energized at station B.

Energization of the relay |008 at station B causes the relay |028 to be energized through the following circuit: from the positive side of the "Z1/9, volt battery, through the conductor 930,

Energization of the relay |028 at station B closes the following circuit through the primary of the buzzer modulating device 949 at that station: from the positive side of the 'Z1/2 Voltbat-l tery, through the conductor 92|, through) the primary of the buzzer modulating device 949, through the conductor 946, through the contacts |032 (now closed) of the hook switch |026, through ther conductor |033, through the contacts |034 (now closed) of the relay |028, through the conductor |035, through the contacts |036 (now closed)l of the relay 94|, through the

conductors

933, 921, back to the negative side of the '7l/2 volt battery.

Energization of the relay |028 at station B also closes the following circuit through the secondary of the buzzer modulating device 949 at that station: from the positive side of the microphone battery, through' the conductor 950, through the secondary of the buzzer modulating device 949, through the conductor 95|, through the contacts |030 `(now closed) of the relay 94|, through the conductor |039, through the circuit interrupting device 920, through the conductor |040, through the contacts |04| (now closed) of the relay |028, through the contacts |042 (now closed) of the relay |028, through the conductor |003, through the contacts |044 (now closed) of the hook switch |026, through the conductors |045, 961, to one'side of the microphone input whose other side is connected through the conductor 963 and the condenser |968 to the positive side of the microphone battery. i

Energization of the relay 910 at station 1? establishesthe following circuit through the relay 929: from the positive side of the, 7%; volt battery, through the conductor 930, through the relay 929, through the conductors 93|, 913, through the contacts 914 (now closed) of the relay 910, through the conductor 921, back to the negative side of the 7,1/2 bolt battery. Maintained energization of the filament control relay 929 in the circuit last traced, maintainsV current on the laments of the tubes of the radio receiving apparatus and the filament of the tube 934 at stationB.

'The following circuit through the relay 918 at station B is established due to the removal of the head piece |025 from its hook and due to energization of the relay |028; from the positive side of the r11/2 volt battery, through the conductors 930, 919, through the relay 918, through the

conductors

conductors

933, 921, back to the negative side of the r11/2 volt battery. Removal of the receiver |025 from the hook of the hook switch |026 opens the contactsv ||0| thereof and closes its contacts H03 to render the cam 983 ineiective and to place the cam switch'll04, whichisloperated by the cam |02, in circuit so as to mak'e'the transmitting and receptive periods at station B in accordance with the program imposed by cam |02, the circuit being as follows: during transmission periods at station B; from the positive side of the 7,1/2 volt battery, through the conductors 92|, 930, through the relay 931, through the conductor 985V, through the contacts H05 (now closed) of the cam switch |04, through the conductor |06, through the contacts H03 (now closed) of the hook switch |026, through the conductor 986, through the contacts 982 (now closed) of the relay 918, through the conductor 981, through the contacts 988 (now closed) of the relay 910, through the conductor 921, back to the negative side ofthe '1l/g volt battery.

agaocgaai During? receptive periods'at the called station,

i.e.,station B, the transmitter-1I at that station is rendered inoperative by energization of the relay990`by the contacts I |01 of the cam switch 3 ||04Lin the following circuit: from the positive side ofthe'l 1/2 volt battery, `through thereonductor 92|, through the re1ay-990, through the conductor 99|, through the contacts ||01 (now closed) "of the cam switch I |04, through the con-L ductor "H06, through the contacts ||03 (now 981, through the contacts 988` (now closed) of the relay ,910, through the conductor 921, back to the `negative side of the r11/2 volt battery.

Removal of the receiver |025- from the `hook t switchy |026 also causes contactsv |08 of thehook t switch to open and contacts ||09 to close, ,thus

relay |003 at station A.`

placing the contacts ofthe cam switch ||04 in circuit to maintain energization `of the relay |008 during transmission periods so "astto prevent removal of modulation `from the carrier of station B due to deenergization of the relay |008 .byshutting down of the receiver at station B during transmission periods, the maintaining circuit of the relay |008 being as follows: from the positiveside of the 'l1/2 volt battery, through the conductor 92|, through the conductor `922, through the conductor |||2, through thecontacts H09 (now closed) of the hook switch |026, through the conductor through the contacts |||0 (closed during transmission) of the cam switch i H04, through the conductor |02I, through the contacts |020 (now closed) of the relay |0l5, through the conductor |||3, through the relay |008, throughthe

conductors

926, 921, back tothe negative side of the '1l/2 volt battery.

`Energization of the relay 918 at station B reni dersfthe key 98| ineifective and renders control bythe cam ||02 effective. l

By theforegoing operations at station B, that station is now transmitting an interrupted modulated carrier (the modulation being interrupted.`

H02' are opposite the adjacent cam switch ||0||,`

the radio transmitting apparatus at station Bis rendered `inoperative and the radio receiving api terrupted by the circuit interrupting device 920,`

such transmission taking `place during the low `spot intervals of the cam |02 at station B. During` the high spot intervals of the cam ||02` at` station B, theradio receiving apparatus at that station is in receptive condition; i l

The user `at station A upon hearing his bell |0|2 is thereby informed that station B has received his call and that the user at that station has removed` his head piece from `its hook. The

user at station A now removes his head piece |025 from the hook of theihook switch |026. Removal ofthe head piece` |025 from the hook switch aty station A automatically opens the contacts 941 of the hookswitch and thereby breaks the circuit of the primary ofthe modulating device 949 at station A. Removal of the head piece |025 from the hook switch at station A opens the contacts 962 of that hook switch and thereby breaks the circuit ofthesecondary of the buzzer modulating device 949 at stationA. Opening of the contacts 941 of the hook switch |026 by removal of :the head piece .|025 at station A also breaks the circuit of the motor 944 at station A. Opening of the contacts941 of the hook switch |026 at stationA also deenergizes the relay 918 so as to vrender the cam 983 inelfective to control transmission and reception and so as to transfer such controlto theikey 98| at station A. The contacts |050 of the key 98| perform the same generalfunction asis performed by the contacts 992 except that whereas the latter are cam-operated the'formerr(|850) are manually controlled. The contacts of the key 98| exercisethe same control as was exercised by the contacts 984 exceptfthat .the latter are cam-operated whereas the contacts |05| are manually controlled. The key 98| is biased to, ornormally in, a position in which the contacts` |050 are closed and the contacts `|El5| are open. By `manual depression of the key 98|, the contacts |050 are opened and the contacts |05|` areclosed. If the key 98| at station A is in the position shown, station A is not transmitting at all. `If at this time the user at station A happened unnecessarily to press the key 98|, an unmodulated carrier would be transmitted from station A. `At this particular time it is unimportant whether station A is transmitting an unmodulated carrier or not transmitting at all; the important consideration being that station A is not transmitting at modulated carrier.y i

Returning now to the called station, that is, station B and again assuming that the drawing represents that station, therelay |002 at station Bnowbecornes deenergized, causing the relays |008 and |0|5 tobecome deenergized during the low spot interval of the cam ||02 at station B. Deenergizationof therelay |008 at station B causes the relay |028 at station B to become deenergized and` thereby cause the following operations to take place at station B.

Deenergization of the "relay |028 `at station B causes the contacts |034 to open and thereby deenergize the relay 918 at station B and also the primary circuit fof the buzzer modulating device 949 at that station. Deenergization of the relay |028 at stationB causesits contacts |04| to open thereby breaking the .secondary` circuit of the buzzer modulating device 9491at station B. Opening of the contacts |034 of the relay |028 by deenergizationof f the latter also breaks the circuit of the `motor 944 atstation B.

Deenergizationfofftherelay |008 at station B,

this time a coded and the fact that the contacts |052 of the hook 15;

closed) of the hook'switch |026, through the'conductors 033.1and 927|, back to the negative side of the 7%; voltbattery.

Energization of the relay |053 disconnects `the primaryof the input transformer` |060 of thetube 934| from-the. radio receiver atzstation B and con- Snects the output of this radioreceiving` apparatus to. the primary ofthe transformer I 06|, across f the secondary of Which. the head piece |025' is'directly connected. The microphone transmitter |0021at stationB'is now eiectively connected inv the following: circuit: from the positive side of'the microphone battery, through the conductor 950', through the contacts |003 (now. closed) of the 'hook switch. |026, through". the conductor` |064, through. they microphonev transmitter |062; through the conductor |065,

through they contacts |006 (now;closed ofthe. |028,- through the contacts.L |061 (now` closed) .of the same relay, throughthe. conductor |060, through the contacts |069'(n0w;closed) of: the lhook switch |026, through the. conductors. |005, 907', to one side of the microphone inputv relay Whoseother side is connected through the conduct'or 000:1;0 theV negative side of the: microphone battery.

Station B is now in condition for speech reception when the key 98| is in the position shown,` and isin condition for speech transmission when the key 98|. is manually depressed by the'user at station B.

Returning now to .station A (i. e., again `assuming that the drawing represents ,stationr A) and havingjin mind that the modulation has been removed from the carrier.y transmitted from station B,- the relay |003 at station A becomes Voleenergized, causing the relays |008 and |0|5 at station A to become deenergized.

Deenergization ofthe relay |008 at station A causes the relay |053'A at thatstation to become energizedwhich results in connecting the pri- 50|( mary of the transformer |00| at that station to the youtput of the radio receiving apparatus thereof and in rendering the tube 934' ineffective. Effective connection of the microphone transmitter |002-at station A in series with the micro- 55,phone `battery and the microphone input at that station, is established by deenergization of the relay |028 bydeenergzation of the relay |008 and the opening of its contacts |029. Station A is'now in condition to. transmit speech When the gkey 08| is manually depressed and to receive speech when the key Qfl'is released, i. e., in the position shown. y Y

When. either user atstations A and B desires to talk he depresses his key 08| and when he is 65,;,not-talking he permits the key to stay in the position shown` in; the drawing, or to return to that position.

After. conversation has ceased, the head pieces |025 at both stations are returned to the hooks 70,"of1-:their hookswitches and the user at station A throws-:this call switch 940 to the off position. These :operations restore stations A and B to their s normal periodic monitoring condition.

' .Thopefrationswhereby any of the four sta- 76j; .tions of'this system; may. call anyy desiredone mers.

ofi-the. other; threesstationsiwill, itis believed, be understood-'in View vof the foregoing description.

Itfwill :bexunderstood that-the system may be eX-iv tendedfto more ,than four stations if desired.

While notessential; I prefer to provide a pilot light. at.;eachystation, to indicate Vwhen the call Switchat-,that station has been operated at its` calling positionjandto indicate the operation .of themotor. 923. at that station. The pilot light 60 is shown connected in parallel with the winding of the, relay 929,- and beingenergized With thatwinding, the pilot light 60 will -light when any callr switch is moved'to calling position and also when the vreceiver-energizing contacts of the cycling mechanism are closed by that mechanism atthe station. The pilot light blinks or `ilashesin response to periodic closure of those contacts, thus providing av visual monitoring of the apparatus. n

While ythe functionsgperformed by the key 98| may be automatically performed by any one of various known types of speech-operated relays, which may have its winding energized by the speechv amplier'or otherwise, I have, for simplicityV in illustration, chosen to show the manually operated key98l. v

Thegbuzzer modulating device shown at 949 may be ofthetype comprising a transformer, in

the primaryircuit of which, a microphone transmitterfbutton is connected in series to. act as an interrupter; `the microphone transmitter button being mounted on a reed so as to impart a mechanical `resonance characteristic to it, the reed being mechanically operated as an armature by thecore of the transformer. Such a device is generally similar to the well-known induction coil havingan interrupter in its primary circuit actuated by ther c oreupon which the primary and secondary windings are Wound. The secondary winding of the transformer constitutes the'output of the device. Such devices are readily available andare known as microphone hum- It willbe understood, of course, that other formsofdeyices may be substituted for this particulartypeof-'tone generator, as for example,

audio frequency.;oscillators, etc.

The mechanically tuned relay shown at |002 and |003l may-be of the type shown in Figs. 10 and, 1l;l of Australian Patent No. 23,313/35, for Improvements in or relating to Wave signalling systems,accepted July 1, 1936,'` and in Figs. l0 and llfofBritish Patent No. 459,235 for Improvementsiin orrelating to radio wave signalling systernsgranted April l, 1937 (each of said patentsgbeing issued'to Wallace Sz Tiernan Products,l 1nd,) It willbe understood that the entire aploaratiilsshownV in Fig, 10 of each of the patents just cited, is such as may be included within the casing.` or b oX` shown at |002 or |003. Other formsof mechanically or electrically tuned or selectivedevices may be used in lieu of the particular-mechanically tuned device shown in Figs. 10 andgll of the cited patents.

In accordance with the provisions of the patent statutes,l I haverherein described the principle of operation of my invention, together withv the apparatus which I now consider to represent the best embodiments.A thereof, but I- desire: to-

havelit understood that` the apparatus disclosed is only illustrative and that the invention can be carried out by othenmeans. Also, while it is designed to usethelvarious features and elements ,in.` the combinations; and relations described, someof. theseimaygbe altered and othersv omitted and some of the features4 of' each modiaeoaasr `mittingmeans and control devices for effecting energization of the same,` call switch means, and meanscontrolled by the call switch means and including periodically operated contact devices in circuit with the receivercontrol devices and periodically operated contact devices in circuit with the transmitter control devices, for repetedly and at respectively successiveintervals efl fecting operation of the wave transmitting means switch means at each station for bringing one and `of `the wave receiving means.`

,2i `The combination of ,claim 1` including also a signalling device, anenergizingcircuit therefor controlled by the `receiving means, means for arresting the periodically operated contact devices, andcommon control means for operatingsaid arresting means and for opening the energizing circuit of the signalling device.

3; Inba wave signalling` system, in combination,

a plurality of stations eachincluding wave transmitting means and wave receivingr means, a plurality of selectable circuit interrupting devices at each station for effecting modulation of the carrier set up by the transmitting means, `at different frequencies respectively corresponding to the other stations, a `circuit `interrupting device at each station for effectingmodulation of the carrier set up bythe transmitting meansat another predetermined frequency common to all stations,

` means at each station controllable by the receivof `the selectable circuit interrupting devices into controlling relation with the transmittingmeans `and for bringingzthe second relay device under control of thereceiving `means `in `place of the rst relay device and independent call-replying circuit-controlling devices at each station for bringing the common `frequency circuit 4interrupting `device into controlling relation with the transmitter.

4. In a station of a wave signalling system,

wave transmitting apparatus, wave receiving apparatus, switch means for controlling the transmitting and receiving apparatus, and means responsiveto anoperation of said` switchfmeans for repeatedly land alternately initiating trans-` mission to another station and conditioning the receiving apparatus to respond to reception of waves from said other station, selective relay means responsive only to a predetermined calling modulation, selective relay means responsive only to a predetermined replying modulation, means connectingthe first-mentioned relay means for control by the receiving apparatus when the aforesaid switch means has not been operated, and means responsive to the operation of the switch means for connecting the second-men- -tioned relay means under control `of thereceiving apparatus in lieu of the rst-mentioned relay means. y

5. In a station of a wave signalling system, wave transmitting apparatus, wave receiving apparatus, and means for controlling said apparatus, comprising call switch `meansreply switch means, means responsive to an operation of the call switch means for repeatedly and alternately y initiating transmission of a call to another station and conditioning the receiving apparatus to respond to reception of waves from said other statiommeans responsive to operation of the reply switch means when the call switch means has not been operated, for initiating transmission of a reply call to another` station in answer to an original` calllfrom` said other station, and means responsive to operationof said call and reply switch means in succession, for maintaining the transmitting apparatus inoperative and for con-` tinuously` conditioning the receiving apparatus for reception of waves.

6. In agstation of a wave signalling system; Wave transmitting apparatus, `wave receiving apparatus, switch means `for controlling the transf mitting and receiving apparatus, means operable when the switch means has not been operated, for v,periodically energizing `,the receiving `apparatus to render `it `operative during the intervals of energy supply and thereby to conserve energy in` listening for calls from anotherstation, and means responsive to `an operationof said switch means for repeatedly and alternately initiating transmission to another station and conditioning the receivingapparatus to respond to reception of waves `from said other station.

'7. In a station of a wave signalling system, wave transmitting apparatus,wave receiving apparatus, and control` means therefor comprising call and reply switch means selectively operable to callv another stationand to reply to a call received from another station, means responsive to an operation of the call switch means for repeatedly and `alternately initiating transmission to another station and conditioning the receiving apparatus to respond to reception of Waves from said other station, in `accordance with a predetermined program, and means responsive to an operation ofthe reply switch means for repeatedly and alternately initiating transmission to another station and conditioning the receiving apparatus to respond to reception of waves from the last` mentioned other station, in accordance with `a predetermined program which is substantially different from the first-mentioned program, whereby two-way call signalling may be effected with another stationwhich has transmitted a call inaccordance with a program identical with the first-mentioned predetermined program.` i

`8. In a wave signalling system, a plurality of stations eachhaving Wave transmitting and receiving apparatus, means at one of the stations forperiodically energizing the receiving apparatus to render it operative during the intervals of energy supply,l said means including control means limiting the duration of said operative intervals to a predetermined time substantially shorter than the intervals when the receiving apparatusis not energized, and at another of the stations, switchmeans, for controlling the transmitting and receiving apparatus, including means responsive to an operation of said switch means forperiodically and alternately initiating transmission to the rst station and conditioning the receiving apparatus to respond to reception of M,

waves transmitted from the rst station, during immediately successive intervals and with the receiving intervals substantially shorter in duration than the periodic receiving intervals at the rst station.

9. A wave signalling system having a plurality of stations and comprising: at one station, wave transmitting apparatus, wave receiving apparatus, switch means for controlling the transmitting and receiving apparatus, and means responsive to an operation of said switch means for repeatedly and alternately initiating transmission to another station and conditioning the receiving apparatus to respond to reception of waves from said other station; and at said other station, wave transmitting means adapted to transmit a characteristic call and switch means for interrupting transmission of said characteristiccall therefrom; said first station having means controlled by its receiving apparatus and operable in response to cessation of said characteristic call from the other station, for interrupting operation of the means for alternating transmission and reception at the rst station.

l0. In a wave signalling system, in combination, a plurality of stations each including wave transmitting means and wave receiving means, modulating means at each station for selectively modulating a carrier, set up by the transmitting means, with any selected one of a plurality of diierent predetermined selective characteristics respectively corresponding to the other stations or with another predetermined selective characteristic common to all stations, whereby each station may transmit either a calling carrier modulated with any selected one'of said plurality of characteristics or a replying carrier modulated withsaid common predetermined characteristic, and selective relay means at each station contrcllable by the receiving means and settable to respond only to received modulation of a calling carrier of selective characteristic corresponding to the station or to respond only to received modulation of a reply carrier of common selective characteristic, whereby a response may be produced at the station in response to reception of either a calling or a replying carrier.

1l. In a station of a wave signalling system,

v wave receiving means, wave transmitting means,

n a carrier modulated by said primary modulating means and also by a selected one of said plurality of selectable circuit-interrupting devices to call another station, and reply switch means for initiating transmission of a carrier modulated by said primary modulating means and also by said other circuit interrupting device to eilect a reply call in response to a call received by the receiving means from another station.

l2. In a station of a Wave signalling system, wave transmitting means, Wave receiving means, call switch means for causing the transmitting means to call another station, selective relay means. controllable by the receiving means and responsive only to one or another of two different predetermined signalling modulations of a carrier received by said receiving means, means operable when said call switch means has not been operated, for causing said relay means to be responsive only to a predetermined one of said two modulations, to listen for calls from another station, and means responsive to operation of said call switch means, for causing said relay means to be responsive only to the other of said modulations, to listen for reply calls from another station.

13. In a station of a Wave signalling system, wave transmitting means, Wave receiving means,

means for producing an alarm signal selectably in response to reception of carriers having one or another of two different signalling modulations, said last-mentioned means having selective control means controllable by the receiving means and responsive only to one of said signalling modulations and selective control means controllable by the receiving means and responsive only to the other of said signalling modulations, and means for selectively conditioning the station to listen for an original call, or for a reply call in response to transmission of a call to another station by the transmitting means, said station-conditioning means being adapted to bring one or the other of the aforesaid selective control means into play, respectively in accordance With the conditioning of the station to listen for an original call or to listen for a reply call.

14. In a station of a wave signalling system, in combination, Wave transmitting means,'wave receiving means, selective relay means controllable by the receiving means and responsive only to a predetermined signalling modulation of a carrier received by said receiving means, selective relay means controllable by the receiving means and responsive only to another predetermined signalling modulation of a carrier received by said receiving means, control means for said transmitting and receiving means for selectively conditioning the station to listen for an original call from another station or to listen for a reply cal1 from another station in response to a call sent by said transmitting means, and means controlled by said control means for bringing one or the other of said selective relay means under control of the receiving means respectively in accordance with the conditioning of the station to listen for an original call or a reply call.

JOHN R. MACKAY. 6|