US2239672A - Radio alarm system - Google Patents

Description

April 29, 1941. w 055 2,239.;672

RADIO ALARM srs'i'lm j Filed Feb. 21, 1938 Patented Apr. 29, 1941 2,239,672" mm ALARM SYSTEM William L. Foss, Washington, D. 0., assignor to Howton Radio Alarm Company, Seattle, Wash.

Application February 21, 1938, Serial No. 191,787

Claims.

It is the object of this invention to provide an alarm system, and more particularly to provide an improvement upon the radio alarm system shown in the copending application of James O. Howton, Serial No. 184,713, filed January 12, 1938.

In the present invention an interrupter device is provided, in addition to voice message reproducing means, to impress a code message on the carrier frequency in order that a suitable code message may be broadcast which will be intelligible even though an interfering voice broadcast, from another source, is occurring.

A preferred embodiment of the invention is diagrammatically shown in Figure l of the drawing. Figures 2 and 3 show a time control device, appearing also in Figure l, in other positions assumed by it during its cycle.

The transmitter and control system here shown are essentially the same as that disclosed in the aforementioned Howton application. Several changes have been made in the wiring hook-up in order to connect the code signalling means into the transmitter circuit.

The transmitter disclosed in the Howton application is designed to broadcast on police and fire wave lengths. The protective system is so arranged that, when a burglar attempts to enter frequency is imposed upon the grid of a tube II, to the plate circuit of which is connected an inductance I2. ,The inductance has a variable condenser l3 connected across its terminalsand a test jack l4 connected in line with a choke coil l5 which is in series between one terminal of the inductance and the positive terminal of a motor generator set IS. The test jack is provided I through the series circuit containing choke' l5,

the secondary of a modulation transformer 2|, and a test jack 22. Jack 22 provides a connecting means for a meter while tuning this stage of amplification. A code signalling device .15

. connected in series-with the cathode of tube. [1,

the operation of'which will appear below.

the building or when a fire is detected,- an appropriate alarm message will be sent out to the authorities. The system embodies a relay control mechanism that selectively actuates a voice alarm reproducing device to cause the desired message to be played into the transmitter and at the same time renders the transmitter operative.

The present improved alarm system in addition to performing all of the above also sends a code message. It has been found in practice that when the relatively low powered transmitter unit in the protected premises is broadcasting and at the same time the central police radio transmitter, is broadcasting, the more powerful police station will interfere with the voice message being sent out by the smaller. set. This difliculty has been overcome by providing a code signal in addition to the voice message. With this means it is possible to broadcast an intelligible signal over a wide area, for though interference will still take place, the code. message will over-ride and will be discernible over the interfering voice messages of the central police broadcasting station.

Thetransmitter has a piezo-crystal ill to control the radio frequency. The controlled radio 55 the other element 32 of this P1 8 e tor to.

Modulation of the radio frequency is accomplished by impressing the voice frequency upon the grid of a tube 23, the plate circuit of which is connected to the grid of a tube 24 in the next stage of amplification. The plate of tube 24 is connected to the primary of a transformer 25 the secondary of which is connected through a push pull circuit 26 and 21 to the primary of modulation transformer 2|. The secondary of this modulation transformer is connected, as 'above described, into the plate of tube l1 and in this manner the voice frequency is superimposed upon the carrier frequency.

I The modulated radio frequency currents thus created in the primary coil IQ of a radio frequency transformer 30 induce a current fiow in its secondary which is in the antenna circuit. This antenna circuit is grounded through condenser 3i and the desired signal is thus broadcasted on the fire and police frequency to the fire and police authorities.

The above described circuit is designed to be compactly mounted within a suitable tamperproof casing and all the necessary leads are brought to a central point where they are connected to a socket element 32a of the multiple point plug connector 32. The controlling means, responsive to the burglar and fire alarm circuits of the building, is adapted to be connected by the radio transmitting set to cause its operation when need be.

The controlling means for causing the operation of the transmitter, the code signalling device, and the voice alarm message reproducing means, is a system of relays connected between the fire and burglar alarm circuits and the radio transmitter. An electrical pickup impresses a recorded voice alarm message on the audio stage of the transmitter, the particular voice message which is broadcast depending upon which alarm circuit is disturbed. If both circuits are disturbed the twomessages will be broadcast in alternating relation as will appear more fully in; fire alarm circuit through the building is normally open and the burglar alarm circuit normally closed, as shown in Figure 1. When 2h: building is closed for the period to be protec e the apparatus-is set and through the circuit described below suitable relays are actuated to cause the operation of the alarm message reproducing means and the transmitter.

A support bar provides a row of suitable contact points or terminals A to J and the cor:i trolling circuit is hooked up through these poin in the following manner:

' minal to points F, H, and J and with its negative rmm' al to point E, the negative side of the b l irglar and fire alarms being connected to point E also. From point J a lead is provided that normally supplies current through contact 34 to relay 33 to point I which forms the positive or current supply terminal for the normally closed burglar alarm circuit. The point H is connected through normally deenergized relay 5! to point G.

The fire alarm circuit is connected across points E and G, this circuit normally being open, a potential is established across its terminals, such that a current will fiow when the circuit is closed. Point F is connected to the normally open contacts 35, 40 and 53. Whenever e ther one of contacts 36 or 53 is made the circuit continues through relay 38, plug element 6|! of a two contact connector. The corresponding socket element 60a of the connector continues the circuit through stop contact 39, back to the plug 50, and then to the point E. If the contact 40 is made the circuit continues through contact 4| to point C. The contact is connected to the motor of the moton generator set l6, which motor is.

de to int D, which is connected to point lf on ectgi in parallel between points C and D are the motor 45 of the sound reproducing means and a supply for the filaments of the-tubes of the transmitter which supply is connected to contacts 45 and 41 of plug element 32. The parallel circuit including the motor 45 has a switch 6|, connected in series with the motor, that may be manually operated or that may be actuated by the voice alarm message reproducer to stop this voice alarm mechanism. Connected across points 45 and 41 of socket element 32a is a circuit through the motors 58 and 59 of the code i allin means. 'l l' he po sitive side of the generator of the motor generator set is connected to point A, the negative side to point B. Point A is connected to contact 43 of plug 32. Point B is connected to contact 44 and also forms a ground for the pickup arms 50 and 5|. The pickup 55 is connected into circuit through the transmitter by contact 31 of relay 33, one side of the contact 31 being connected to contact 43 of plug 33. Pickup 5| is connected to contact 54 of relay 53, contact 54 being connected in parallel with contact 31.

The code signalling means is connected with the transmitter circuit in a series circuit including tube H in the second stage of the radio frequency circuit. In the preferred form the code signalling means comprises a wheel 52 havinga suitable code provided on its periphery. A contact arm 84 is adapted to engage the periphery of the wheel and its rotation makes and breaks the circuit through the contact arm in accordance with the code. The contact arm being in series with the cathode of tube II, when the wheel is rotated the cathode circuit is alternately made and broken in a sequence such that the code is impressed upon the carrier frequency. It is obvious, of course, that the code message provided on the periphery of the rotating wheel is such as to apprise the authorities of a disturbance of one of the protective systems about the premises.

The above described circuits being established, the apparatus operates in the following manner:

When neither the fire nor burglar alarm circuits are disturbed the relay 33 remains energized by holding contact 34' closed establishing an energizing or holding circuit through battery 35. Relays 33 and 52 remain deenergized. This condition will prevail until the burglar alarm circult in series with the battery and relay 33, is broken or the fire alarm circuit is made.

When the burglar alarm circuit is broken, it being in series with the battery and the relay 33, the, current supply to the relay is stopped. Consequently the relay is deenergized and contact 34 is broken. While at the same instant contacts 33 and 31 are made. The breaking of contact 34 deenergizes relay 33 and to again become operative it must be manually reset. When contact 36 is made current is supplied from the positive terminal of the battery, to a circuit containing the relay 38, connector ill and the contact 39, back to the negative of the battery. The energization of relay 3!! makes contacts 43 and 4|. The contact 40 being connected to the positive side of the battery, a current supply circuit is established through contact 4| to the motor of the motor generator set I6, which is grounded to the battery and the generator is operated to supply a suitable current (400 volts) to the radio transmitter through contact points 43 and 44 of plug member 32. Being connected in parallel with the motor circuit of the motor generator IS, the small motor 45 arranged to drive a turntable and the stop switch 5| connected in series therewith and the current supply through contacts 45 and 41 of plug 33 to the filaments of the radio transmitter tubes, these elements of the system are rendered operative by the closing of contacts 43 and 4|. The energization of contacts 45 and 41 of socket element 32a causes the operation of the motors 58 and 65 of the code signalling means.

The code signalling device is designed to operate for a short period before the. voice alarm message is permitted to be sent. Then the code message is blanked out for an interval and the voice alarm message is rendered intelligible throughout the area where no interference takes place. After the voice alarm message has been broadcast for a sufflcient period, the code signalling device is again connected into the circuit so that the code message is impressed upon the carrier wave and sends the code message into such areas in which the voice alarm may have been interfered with.

To perform the above sequence of operations the cam element 66 is driven by the motor 63.

and the code wheel 62 is driven by motor 63.-

These motors connected in parallel with the filament supply are energized as above explained and through suitable gear trains drive the cam and code wheels respectively. At the beginning of operations the cam wheel is in the position shown in Figure 1. Surface does not engage contact 66 and the code message is impressed upon the carrier frequency as above described. When the cam has rotated to the position shown in Figure 2 surface 10 engages contact 66 short circuiting the code wheel and rendering the cathode continuously energized while the contact continues in engagement with the surface so that the voice alarm may be broadcast. As the cam continues its rotation and surface 10 is disentracks is in position on the turntable and each track cooperates with a suitable electrical pickup. The two tracks are provided on one record so that from one track a message that the building is being broken intomay be reproduced and from the other a message may be reproduced to the effect that a fire has been detected. The recordings on the difierent tracks are so related that in the case where both burglar and fire messages are required, first the burglar message 'will be given, then the fire message, the alarm messages will alternate in this manner, until the starts the transmitter, code sending device, and turntable. The making of contact 64 establishes a circuit through the fire message pickup ii and the grid of tube 23 of the audio-frequency stage of the transmitter. In this manner the code and voice alarm messages are broadcast calling attention to a. fire within the protected area.

In the event that the burglar and fire alarm circuits should both be disturbed the relay 33 is deenergized and relays 33 and 52 are energized. The deenergizationof relay 33 energizes relay 33 to set the transmitter and code device in operaand the transmitter is thrown out of operation.

tion and establishes a circuit through pickup 60. The energization of relay 62 establishes a circuit through pickup 5|. The transmitting set under these circumstances having both pickups and the code device in circuit with'it, broadcasts both voice and code alarm messages. The record from which the voice alarm messages are being reproduced having the two nonconfiicting series of tracks as above explained, the alarm messages do not interfere with one another when the voice v alarm is being broadcast.

If the. transmitter should accidentally be set in operation, in order to prevent false alarms being sent out a manual controlof the contact 39 is provided. It is possible by operating this contact to break the current supply through the relay 33. When this happens contacts 40 and it are released and break contact, the current supply to the motor of motor generator I6 is stopped,

It is, of course, obvious that the set and the contact would be situated in some concealed position to render it inaccessible to unauthorized persons.

Whenever the protective system has been called into action it will continue to broadcast for a predetermined period of time. This period is controlled by the arm 61 of the cam and contact 33, 1. e. the set will broadcast until the arm actuates the contact. This, as above explained,

sound reproducer is stopped by the actuation of respectively. As above stated the deenergization of relay 33 causes contacts 36 and 31 to be made. The circuits established by contact 36 prepare the radio transmitter for operation. The making of contact 31 connects the burglar message pickup into a circuit through the plug 32 to the grid of tube 23 of the audio frequency stage. The transmitter already being in operation the appropriate message reproduced through pickup 50 will be broadcastto the police authorities. 4

Referring to the condition of the alarm system when it has been properly set for guarding the building it will be remembered that the relay 33 is energized holding contacts 36 and 31 broken and making contact 34. In this circumstance when the fire alarm circuit is made, i. e. when a thermostat-in the circuit is heated to such a temperature indicative of fire that it closes the circuit, a current is caused to fiow in relay 52 stops the motor generator set and renders the transmitter inoperative. In order to again condition the set for operation it is necessary to reset the relay control system. This is done by closing the burglar alarm circuit and/or opening the fire circuit making it possible to reenergize relay 33 by making contact 34. The cam 65 is reset and also pickup arms 50 and 5i. The contact 33 is made and the system is in operative position to protect the building.

The relay control system like the transmitter is compactly designed to fit within a tamperproof casing and has all of its leads that cooperate with the transmitter brought out to the plug element 32 of the multiple connector and plug element 60 of the two point connector. The other leads of the control system, which are connected to the burglar. and fire alarm "circuits, the battery, and the motor generator set are brought any building to be protected by this apparatus is first wired withproperly designed fire and burglar alarm circuits. These circuits are connected to the terminal support bar of the concealed control unit and the control unit is plugged into the transmitter unit. As soon as a battery and motor generator set have been connected up, the system is in condition for operation. By this means a thoroughly reliable, compact, and simple broadcasting station is situated in the building to be protected and the unit is effective to automatically call the P lice and/or fire department upon any tampering with the building.

It is obvious, of course, that the normally closed burglar alarm and the normally open fire alarm circuits could be interchanged so that a closing of the burglar circuit and an opening of the fire circuit would initiate operations. However the preferred hookup is as above described. Other modifications will appear to those skilled in the art, all of which are included within the scope of the appended claims.

I claim:

1. A radio alarm system comprising a transmitter including a plurality of tubes and alarm message producing means in connection with said transmitter, said means including code signalling means and a motor for said last named means, means for blanking out said code signalling means and a motor to drive said blanking means, said motors being connected in parallel with each other and in parallel with the filament supply circuit for said tubes, means for controlling the operation of the last named means, said alarm message producing means including also voice message producing means, and means for operatively connecting said voice message producer with the transmitter while the code Signalling means is blanked out, said alarm system being adapted to transmit a warning of a disturbance on a protected premise, said voice message producing means being eifective when actuated to cause a warning signal to be broadcast and said code signalling means being effective when actuated to send an intelligible signal into zones of possible interference.

2. A radio alarm system comprising a transmitter and alarm message producing means in connection with said transmitter, said means including code signalling means, means for blanking out said code signalling means including a plurality of successively operated circuit controls,

one of said contacts making a short circuit around said code signalling means, another of said contacts being operative to stop said transmitter, means for controlling the operation of said blanking out means, said alarm message producing means including also voice message producing means, and means for operatively connecting said voice message producer with the transmitter while the code signalling means is I blanked out, said alarm system being adapted to transmit a warning of a disturbance on a protected premise, said voice message producing means being effective when actuated to cause a warning signal to be broadcast and said code signalling means being effective when actuated to send an intelligible signal into zones of possible interference.

3. An alarm system including a radio transmitter havihg an audio frequency stage and a radio frequency stage, said last named stage including a cathode tube, a plurality of different voice alarm messages, means to cause said different messages to be selectively impressed upon said audio frequency stage, a code message adapted to be impressed upon the cathode of said tube, means to initiate said voice alarm and said code alarm to cause a broadcast thereof, and means to cause said code message to override said voice alarm at spaced time intervals whereby the alarm signal is transmitted to distant points irrespective of other voice messages which may be being broadcast on the same wave band as said radio transmitter.

4. An alarm system including a radio transmitter having an audio frequency stage and a radio frequency stage, a plurality of diflerent voice alarm messages, means to cause said different messages to be selectively impressed upon said audio frequency stage, a code message adapted to be impressed upon said radio frequency stage, means to initiate said voice alarm and said code alarm to cause a broadcast thereof, said means comprising a plurality of protective circuits wired around the premises, a relay system between said circuits and said transmitter controlled by said circuits, said relay system being effective to cause an energization of said transmitter and selectively impress the voice alarm message to be broadcast on the carrier frequency, and means to cause said code message to override said voice alarm at, spaced time intervals whereby the alarm signal is transmitted to distant points irrespective of other voice messages which may be being broadcast on the same wave band as said radio transmitter.

5. An alarm system including a radio transmitter having an audio frequency stage and a radio frequency stage, said last named stage including a cathode tube, a plurality of different voice alarm messages, means to cause said different messages to be selectively impressed upon said audio frequency stage, a code message adapted to be impressed upon the cathode of said tube, means to initiate said voice alarm and said code alarm to cause a broadcast thereof, and means to cause said code message to override said voice alarm at spaced time intervals, said last named means including a code producing device and a time driven circuit maker and breaker, said circuit maker and breaker comprising a contact wheel and switch actuating finger serving to sequentially connect said code producing means into series with said cathode tube and then short circuit and code producing means and then again connect said code producing means in series with said cathode and then said finger serving to break the energizing circuit of said transmitter, whereby the alarm signal is transmitted to distant points irrespective of other voice messages which may be being broadcast on the same wave band as said radio transmitter.

WILLIAM L. FOSS.

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