US2070112A - Police-communication system - Google Patents

Description

POLICE COMMUNICATION SYSTEM Feb. 9, 1937.. E, BOWLES 2,070,112

POLICE COMMUNICATION SYSTEM Filed Oct. 5, 1932 4 Sheets-SheetAZ- WWTF-THU H ll MM l flll /jdw @razz/2.0.2273;

@ormey Feb. 9, 1937. E. l.. BoWLEs 2,070,112

POLICE COMMUNICATION SYSTEM Filed Oct. 3, 1932 4 Sheets-Sheet 3 E.y L.. BowlfEs 2,070,112

POLICE COMMUNICATION SYSTEM Filed 00T.. 5, 1952 Feb. 9, 1937.

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Patented Feb. 9, 1937 A 2,070,112

UNITED STATES PATENT OFFICE POLICE-COMMUNICATION SYSTEM Edward Lindley Bowles, Wellesley Farms, Mass.

Application October 3, 1932, Serial No. 636,006

Claims. (Cl. Z50-14) The present invention relates to communica- The radiating elements and |2 are shown tion systems and more particularly to systems by associated with a vacuum tube 2 having a grid which police headquarters may communicate 5, a plate or anode and a filament or cathode with the patrolmen on their beats. I9. The oscillating circuit is completed, in the I According to present-day methods of signalordinary, well known, way by means of coupled 5 ing, a patrolman is signaled by means of signal coils 2| and 23 in the input and the output cirlights located on the different beats. Because cuits, respectively, of the vacuum tube 2. A byof fog or other factors, however, the patrolman is pass condenser 25 is disposed in the output cirnot always able to see the lights. cuit to prevent the direct voltage from a common l0 An object of the present invention, therefore, source 35 of power supply from reaching the fil- 10 is to provide a novel system for communicating ament I9. A radio-frequency choke 21 prevents with patrolmen, thus dispensing with the necesthe radio-frequency energy from reaching the sity for their being always in sight of the signal modulating and power sources. lights. A vacuum-tube oscillator and amplifier, for la A further object is to provide a Simp-le signalmodulation, schematically represented at 3|, is 15 ling system for the police, which may be concapable of producing a given modulation freveniently carried about by the ordinary patrolquency: for example, 500, 800 or 1,000 cycles per man. y second, intended to be within the range of maxi- Another object is to provide a small transmitmum ear sensitivity. The output from this ter and receiver, particularly for police, and modulating unit 3| is coupled to the oscillator of 20 adapted for use with short waves. the vacuum tube 2 by means of a transformer Other and further objects will be explained 33. Both the modulated oscillator and the modhereinafter. ulator unit 3| are supplied from the power The invention Will now be described in connecsource 35, which may comprise either batteries, tion with the accompanying drawings, in which or the usual rectier-and-lter arrangement, 25 Fig. 1 is an elevation of a police call box, equipped converting alternating current into direct curaccording to the present invention, a diagram of rent. The power source 35 may supply, as well, -circuit connections and other electric elements filament-transformer facilities to heat the filabeing embodied therein for clearness; Fig. 2 is a ment I9 or other heating elements of the vacuum perspective View, parts being broken away for tubes necessary for the oscillator and the modu- 30 clearness, of a patrolmans head, his hat, shown lator. When energy is sent to the power supply in dot-and-dash lines, being provided with a from the signalling station (not shown) at preferred receiving system; Fig. 3 is a diagram headquarters, along conductors 4, modulated osof circuits arranged according to a modification cillations will be radiated into space from the ele- 35 of the arrangement shown in Fig. 2; Fig. 4 is a ments and |2. 35

modified circuit diagram; and Fig. 5 is a dia- By making use of exceptionally high, radio fregrammatic view, similar to Fig. 2, illustrating the quencies, it is possible to make this radiating equipment of the present invention as worn by system extremely small and, above all, to make a patrolmans belt. the receiving unit, about to be described, exceed- Referring first to Fig. 1, the usual police call ingly small. 40

or signal box and call light 3 are shown carried The police receiving system is intended to proupon the usual supporting post 5. A radio-sigduce either an audible or a visible signal by naling, transmitting system 1 is shown carried at means of apparatus attached to the patrolman. the top of the post 5. The signaling system I In Fig. 2, for example, the police receiving-system comprises a unit carried in a housing 9 for a genequipment is shown comprising a miniature, tele- 45 erator of radio frequency and a radiating antenphone, sound reproducer 4| that is held close to, na system l2. The receiving-system equipbut separate from, the ear. This miniature sound ment, as will hereinafter appear, is built into the reproducer 4| is` tuned to the modulating frequenpatrolmans uniform. According to this invency of the police transmitter 1, thus yielding the tion, therefore, it is possible to call a patrolman maximum possible sensitivity of this translating 50 who is not, at the moment, in sight of his call element 4|. This sound reproducer 4| is so arlight 3, either because of momentary duties carranged that it will not in any way interfere with rying him outside of the realm of vision of this the normal function of the ear. It is, however, light, or because of fog or other obstructing mounted upon a flexible and spring-like section cause, 45, in order that, if the patrolman should wish to .55

detect an unusually Weak signal, or if, because of local noise, he should Wish to make sure of the signal received, he may momentarily iiex the section 45, thus pressing this sound reproducer element 4| to his ear. The sound reproducer 4| will spring back, away from the ear, When the pressure is released. The spring-like section 45 may be mounted upon headgear, such as a head band 42 (Fig. 5) or other head-harness arrangement that may be Worn immediately beneath the patrolmans cap or helmet 43. It is preferred, hoW- ever, to mount the spring 45 for holding the sound reproducer 4| directly on the hat or helmet 43, as illustrated, upon a fixture 41 which, in turn, is secured to the inside of the helmet or cap 43 in any desired manner. This fixture 41 is provided With clips 49 for retaining the spring element 45, so that it may extend downward below the hat 43 and adjacent to, and separated from, the ear. It may be moved up or down for adjustment to a particular ear or to a particular cap setting.

'Ihe loop 5| is shown in Fig. 2 Wound around an insulating, shape-retaining form or shell 53 that comprises a 'cylindrical outer portion 51, a domelike, inner portion 59 and a fabric, flexible base 6|. It is sometimes desirable to cover the dome 59 With aluminum foil which has been cut radially to suppress eddy currents, as indicated at 91, 99, ||l| and |53. This entire structure, Which is relatively rigid, and relatively free from changes of tuning due to the mechanical movement of the parts, may be fitted inside the cap or helmet.

The terminals I9 and |3 of the loop 5| connect with a variable condenser 55 suitable for tuning the loop to the signal it is desired toreceive. The condenser 55 is provided with adjusting knobs 93 and 95. The tuned loop is associated With a dete'ctor tube 53 which is held in a clamp 5 that is xed to the shell 53. This detector tube 53 is, in turn, associated With a grid leak 65, a grid condenser 51, and batteries 13, 15 and 11 for energizing or exciting the filament of the detector tube 53, and a battery 19 for energizing the plate circuits. These batteries 13, 15 and 11 are respectively held in place by clips 5|, 89 and 9|. The battery 19 is held by clips 83, 85 and 81. A cable 1| carries conductors for furnishing the battery supply to the tube 53 and also for carrying the output leads 8 to the sound reproducer 4|.

'I'he arriving signal .affects the tuned, loopreceiving circuit 5|, 55, thus affecting the detector tube 53 and its associated circuits, giving a signal of the modulated frequency in the resonant sound reproducer 4|.

In Fig. 3, there is disclosed a receiving circuit which will respond Well to both strong and Weak signals. 'Ihe loop antenna 5| .and the tuning condenser 55 are connected in the input circuit of the detector tube 63, which input 'circuit has the Iusual grid condenser 61 and the usual grid leak 65. In the plate circuit, there is connected the resonant sound reproducer 4|, as well as a bypass condenser |91 for radio frequencies. In addition, however, there is included in the circuit a resistor |09, and a by-pass condenser for radio and audio-frequencies. In this circuit, With strong signals, to rectify grid currents, an average bias is produced Which increases negatively with signal intensity, thus preventing overloading. In addition to the signal-curbing device, comprising the elements |39 and lli, a variometer 34 is shown connected in the plate circuit of the tube to introduce regeneration. It may even be so-metimes desirable to make the circuit super-regenerative in any Well known fashion. As is Well understood by those skilled in the art, a straight Wire or open antenna may be used in place of the coil antenna 5|.

In some cases, it is advantageous to carry the receiving equipment on the belt |45, rather than in the helmet 43, as illustrated in Fig. 5. The loop 5| consists of convolutio-ns about the belt. As the belt |45 is split at |4 to facilitate mounting on the person, it is provided With an insulated connecting plate |23. The plate |23 may be connected with the ends of the belt |45 by a plugand-socket connection. Any desired number of plugs |25, |21, |29 and |3| on the plate |23 may engage in a corresponding number of sockets |33, |35, |31, |39, respectively, provided upon the belt |45. The plugs |25 and |3| are connected together by a lead |4I, and the plugs |21 and |29 are connected together by a lead |43. The leads |45 and |43 complete the turns of the loop 5|. There will be as many connecting leads |4| and |43 as there are pairs of plugs |25, |3| and |21, |29 connecting with the turns of the loop antenna 5| on the belt |45. If desired, the loop convolutions may be partly disposed, Where convenient, about supporting straps |41 for the belt |45.

The loop 5| is associated with a tuning condenser 55, in a shielded boX |5|, and provided With an yadjusting knob |53. This knob |53 consists of a large dialed wheel, only a portion of which extends outside the box, as clearly shown in Fig. 5. The condenser 55 is connected to the receiving equipment in a shielding box |51 which, in turn, is connected with a container |59 for holding battery equipment to supply the plate or anode circuit of the detector in the container |51. The container |51 carries the detector tube 63, the grid leak 65, the grid condenser 61 and the plate by-pass condenser |91. These are associated With a filament-energizing battery |61. Shielded leads |69 and |1| connect this receiving circuit with the variable condenser 55 which, in turn, is connected With the receiving loop 5| in the usual The connections are substantially as shown in Fig. 3. At the top of the shielded container |59, there is a double plug |5| the leads of which may be connected to the sound reproducer 4| by means of a plug |53 and a fieXible cord |65.

The audible signals may be used in combination with a visual receiver, in the form of a signal light 25|. It is possible to add to the detector tube 63, and to its associated receiving circuit, an auxiliary circuit comprising a tube |59 of the Thyratron type, that is, a grid controlled larc tube, having a grid 251, a filament 259 and a plate 25|. The signal light 25|, connected in the output circuit of the tube |50, is conveniently xed to the patrolmans cap visor, so as to be always in sight, as illustrated in Fig. 4, the operation o1 Which is as follows:

In the illustrated, grid-condenser, grid-leak type of detection, the average plate current is less dur-ing the reception of the signal than during the absence of the signal. The grid 251 and the filament 259 of the Thyratron tube |50 are connected across a resistor 253 in the plate circuit of the detector 63. The average voltage across this resistor will, therefore, decrease during the presence of a signal. Advantage of this fact is taken by connecting this resistor in series With a battery |55 and the grid-filament terminals of the tube |50. 'Ihe grid 251 may be so biased, by means of the battery |55, in conjunction With the normal voltage across the resistor 253, that, without a signal, it is too negative for the arc discharge to take place between the iilament 259 and the anode 26|. Thus there will be substantially no current in the plate circuit of the tube |50 connected to the light 25|. If, on the other hand, a signal arrives and produces an additional voltage drop -across the resistor 253, it will be such as to decrease the negative bias on the grid 251, thus making this grid more positive with respect to its filament 259 than it originally was, and if the adjustment of the battery |55 is correct, the tube |50 will be caused to break down into an arc discharge between plate and filament upon the arrival of a signal, thus causing the light 25| to glow. In order to extinguish the light, it is necessary to open the plate circuit of the tube |50. This is accomplished by means of a small, push-button, switch arrangement 265, which may be placed at any convenient point on the patrolmans person; for example, it may be secured to his belt. Pressing the button 26'! will cause the contact member 269 to open, thus restoring the tube |59 to its original, trigger-sensitive condition. Upon releasing the button 261, the contact member 269 will become reclosed, leaving the tube |59 once more ready to function upon the reception of another signal.

It will be understood that the above-described embodiments are illustrative merely and that they are shown diagrammatically, to illustrate the invention, and Without any attempt to maintain the relative scale of the various parts. In Fig. l, for example, the radiating elements and l2 of the antenna will, in practice, be raised higher above the housing 9 than is illustrated, in order to produce a vertically and horizontally polarized radiation iield.

Further modications will also occur to persons skilled in the art, and all such are considered to fall within the spirit and scope of the invention, as dened in the -appended claims.

What is claimed is:

1. A receiving system comprising an insulating form and an insulating dome disposed in a wearers hat, a receiving loop wound about the insulating form, a signal indicator suspended from the hat adjacent to the wearers ear, and means connecting the loop and the signal indicator in a receiving system.

2. A radio receiving system comprising a detector having an input circuit and an output circuit, means for picking up the energy of radio waves from a transmitter, tuning means in the input circuit for selecting the energy of the said transmitter, a signal indicator connected independent of the transmitting means in the output circuit, a Thyratron tube connected with the output circuit for controlling said signal indicator and restoring means for said Thyratron tube.

3. A radio receiving system comprising a detector having an input circuit and an output circuit, means for picking up the energy of radio waves from a transmitter, tuning means in the input circuit for selecting the energy of the said transmitter, a signal indicator comprising a lamp connected independent of the transmitting means in the output circuit, a Thyratron tube connected with the output circuit for controlling said signal indicator and restoring means for said Thyratron tube.

4. A radio receiving system comprising a detector having an input circuit and an output circuit, means for picking up the energy of radio Waves from a transmitter, tuning means in the input circuit for selecting the energy of the said transmitter, a signal indicator connected independent of the transmitting means in the output circuit, a second sign-al indicator for indicating when the first-named signal indicator is operating, a Thyratron tube connected with the output circuit for controlling said signal indicator and restoring means for said Thyratron tube.

5. A radio receiving system comprising a detector having an input circuit and an output circuit, means for picking up the energy of radio waves from a transmitter, tuning means in the input circuit for selecting the energy of the said transmitter, an audible signal indicator connected independent of the transmitting means in the output circuit, a second visible signal indicator for indicating when the first-named signal indicator is operating, a Thyratron tube connected with the output circuit for controlling said signal indicator and restoring means for said Thyratron tube.

EDWARD L. BOWLES,

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