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Publication numberUS1940881 A
Publication typeGrant
Publication dateDec 26, 1933
Filing dateFeb 18, 1931
Priority dateFeb 18, 1931
Publication numberUS 1940881 A, US 1940881A, US-A-1940881, US1940881 A, US1940881A
InventorsPorts Earl G
Original AssigneeInt Communications Lab Inc
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Combined receiver and transmitter
US 1940881 A
Abstract  available in
Previous page
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Claims  available in
Description  (OCR text may contain errors)


FIG. 2

" Patented Dec. 26', i

v N TED PATENT OFFICE iCdMBIlvEDiRECFIYER. Ann TRANSMITTER; f Earl G. Ports, Woodsi de, N. .Y.', assignor .t o Inter- :nationalj" Communications Laboratories, 1110., New York, N. Y., a corporation of New York ffApplicati on February 13,1331: serialivasiassi v solaims." orzso -isy v I .This" invention relates to radio communica-. tions systems, and more particularly to adea vicefo'r controlling the volume of sound produced in suchsyster'ns. e

5, Anobject of this invention is the provision of new and improved meansof varying the intensity of the sound given out by a receiver when a nearby transmitter is radiating.

Another object is the provision of means of protecting the ears of the operator from the unpleasant effects of his own transmitted signals.

A still further object is the provision of simple and convenient means for permitting the transmitting operator to listen to the character 5 of his own signals.

' With combined transmitting and receiving apparatus, it is usually necessary for the operator to remove his headphones while he is sending. Otherwise the ears may be injured by the loud-.

zoness ofthe sound due to the large amount of energy picked up from the transmitter by the receiver, even though the receiving antenna be disconnected from the receiver. Oneof the objections to this procedure is that the transmitting operator, i. e; the operator with his headphones removed, is unable to know when the receiving operator desires to cut in and ask a repetition of 'themessage, or make some other request.

. This invention permits an operator to wear earphones while transmitting without risk or discomfort, thus enabling him'to listen continuously to his own signals and to be always on the alert for any signal which may be sent by another operator.

be apparent from a perusal of the specification taken with the accompanying drawing,- in which Fig. 1v is a schematic diagram of one embodiment of my invention, and 40. Fig. 2 is a preferred embodiment, different from Fig. 1 in that a commonantenna is used for the transmitter and receiver.-

Referring to Fig. 1, T indicates a transmitter having an antenna Lsignal key 2 and battery 3. m R is shown a receiver having anantenna 4 and output leads 5, connected to which is any suitable signal detecting device 6, such as earphones, loud speaker or the like. In a relay box '7 is a relay 8, which is connected, with the transmitting key 2 by means of leads 9. An armature 11, controlled by relay 8, is adapted to cooperate with contact 12 and cause variable resistance 13 to shunt the earphones 6." A second variable resistance 14 normally controls the intensity of liel the audible signals in the device 6 p relay 22,thereby switching the antenna from the These and other ob ects and advantages W111 i "The operation i s-as follows; key2 isdepressed and radiation from the transmitter takes, placev I accordingly. The closureof the circuit by the p,

key 2 through the battery 3 and relay. 8 results in attracting the armat'ure 11 andplosingeon 0,. tact 12. This throws resistance 13 across the detector Gand reduces audible effectsof the signals from the transmitter T to approximately zero, thus allowing the operator to wear the'earphones without hearing sounds at all therein. However, resistance 13 may be varied to allow asmall amount of signal energy to pass through the 7 phones so that the operator may hear and listen to the extent desired. l

' In Fig. 2, which is a preferred embodiment of my invention, 15 shows an antenna common to both the transmitter and thereceiverbut normally connected with'the receiver. The circuit may be traced from antenna .15 through contact 16, armature 17, receiver R, armature 18, contact 19 to ground 21. .When key 2 is depressed, relay 22 is energized to attract armatures 17 and 18, thereby opening contacts 16 and 19, and armatures 23and 24 are attracted to close contacts 25 and 26 respectivelyin the'transmitter radiatingfcircuit; which may now be traced from antenna-15 through contact 25, armature 23, transmitter T, armature 24, contact '26 to ground 21, the receiver aerial'circuit now being open. The other remaining parts of Fig. 2 are similar to In this arrangement, key 2 when depressed performs a three-fold function; first, it energizes I to the transmitter only when the key is depressed, or it may be stated that during non-signalling periods or during the small intervals between signals, the antenna is connected to the receiver. This permits reception at all times except when w the transmitter is radiating. Also if an operator at a station being communicated with wants to cut in and ask for a repetition of the messagev or totransmit a more important-message, this. is made possible with the present arrangement as the operator employing the device will be able to detect the incoming signal in the small periods between the signals heis transmitting.

What is claimed is:

1. A system comprising a signal transmitter, a receiver having signal indicating means, an adjustable resistance, means controlled from the transmitter to cause said resistance to shunt said signal indicating means to reduce the intensity of signals from said transmitter to said indicating means.

2. A receiving system comprising a receiver having signal indicating means, an adjustable resistance normally disassociated therefrom, a transmitter for signalling, and electromagnetic means controlled by said transmitter for causing said resistance to .shunt said indicating means to reduce the intensity of signals from said trans-' mitter.

3. In a combined transmitting and receiving system, a receiver having an output circuit, a transmitter, a common antenna therefor, a resistance normally disconnected from said receiver, a relay associated with said resistance, and means for controlling said relay to connect said resistance to said receiver, said resistance being adjustable to vary the intensity of the signals received from said transmitter.

4. In a combined transmitting and receiving system, a receiver having an output circuit, a transmitter, a common antenna therefor, normally disconnected from said transmitter, a resistance normally disconnected from said receiver, a relay, and means comprising a key to connect said antenna to said transmitter and to actuate said relay to cause said resistance to shunt said receiver output circuit, said resistance being adjustable to vary the intensity of the signals received from said transmitter.

5. In a combined transmitting and receiving system, the combination of a transmitter and a receiver, an adjustable resistance normally connected to the output of said receiver, a second adjustable resistance normally disconnected from the output of said receiver, a common antenna normally connected to said receiver and disconnected from said transmitter, means for disconnecting said antenna from said receiver and connecting it to said transmitter, and means for connecting said second resistance to said receiver.


Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US2533493 *May 31, 1946Dec 12, 1950Motorola IncPortable radio device
US2577751 *Mar 24, 1945Dec 11, 1951Farnsworth Res CorpRemote supervisory radio signaling system
US2864942 *Mar 11, 1955Dec 16, 1958Aircraft Radio CorpReceiver tuning in two-way radio
US2868964 *Jun 21, 1955Jan 13, 1959Rca CorpRadiotelephone switching circuit with receiver squelch control
US2883521 *Oct 23, 1952Apr 21, 1959Motorola IncRadio dispatching system for railroad use
US4716576 *Jul 16, 1984Dec 29, 1987Kabushiki Kaisha KenwoodApparatus for controlling transmitter-receiver
U.S. Classification375/219, 346/33.00M
International ClassificationH04B1/44
Cooperative ClassificationH04B1/44
European ClassificationH04B1/44