US 2146724 A
Description (OCR text may contain errors)
Feb. 14, 1939. F. w. DUNMORE 2,146,724 RADIO SYSTEM FOR COLLISION PREVENTION Filed y 1933 2 Sheets-Sheet .1
II II Feb. 14, 1939.
F. w. DUNMORE 2,146,724 RADIO SYSTEM FOR COLLISJ ION PREVENTION Filed May 11, l933 2 Sheets-Sheet 2 FIGURE 2 A? I m Kym, qJ
gin/09mm JW 209W the and a directional secondary Patented Feb. 14, 1939 UNITED STATES RADIO SYSTEM Fon COLLISION PREVENTION Francis W. Dunmore, Washington, D. 0., assignor to the Government of the United States,
resented by the Secretary of Commerce Application May 11,1933, Serial No. 670,423
(Granted under the act of March 3, 1883, as
' amended April 30, 1928; 370 0.
The invention described herein maybe manufactured and used by or for the Government of United States for governmental purposes only, without the payment of any royalty thereon.
mitter and receiver for use on a mobile. object, both receiver and transmitter operating on the same radio frequency and both operating in effect simultaneously, thatis, at an audio frequency rate or higher, without interference. The receiver having a directive antenna makes possible the determination of the direction to a second mobile object equipped with similar apparatus, thus avoiding a possible collision.
In this invention the transmitting set and receiving set are operated in a push-pull fashion such that when the transmitter is in operation the receiver is rendered inoperative. This changeover is made sufliciently rapid that the receiver is in effect continuously operative for the detection of signals from a second mobile object. Other uses for and advantages of my invention will be more clearly understood by reference to the following description and diagrammatic drawings.
In these drawings- Figure 1 shows the circuit arrangement of one form of my invention in which a high frequency transmitting and receiving set are used with a double transmitting antenna to prevent shadows receiving antenna.
Figure 2 shows the application of this invention to an airplane when .the two transmitting antennas are located on the wing tips and the directional receiving antenna amidship.
Figure 3 shows the application of my invention to the marine type of low power mobile beacon now coming into use, showing the ships direction finder which may function while the mobile beacon is operating on the same radio frequency and on the same ship without interference.
In the form illustrated in Figure 1 the output from a high frequency transmitting set, I serves as a means for feeding antennas 2 and 3 through transmission lines 4 and 5. The'antennas 2 and 3 are so located one on each wing tip that a signal will be sent'in all horizontal directions without shadow effects. with one end of the secondary supplying power to the plates of transmitting set I. A resistance 1 shunted across part of this same end of the supplies negative bias voltage to the grid of last tube 8 in a high frequency receiving set 9. The other portion of this secondary sup- My invention relates to a combination trans- 6 is a center tap transformer plies the plate of transformer. A circuit the tube 8 through an audio I2 may be of the superregenerative type, the input of which is connected to a direction antenna I3 which may be orientable about a vertical axis and collapsible so that it folds down within the airplane. I4 is an oxide rectifier and I a current indicating means. A- direct current bias is supplied from a suitable source, which may be a battery I6. The alternating current bias on the grid of the tube 8 may be set at the proper value reading on I5 with no signal coming in; by means of a slider I1. Alternating current is supplied from a suitable source I8.
The circuit functions as follows: This transmitter functions alternating current voltage supplied at I 8, when the plates of the tubes in the transmitting set I become positive. During this half-cycle, however, the plate of the tube 8 is negative rendering it inoperative so that the signal sent out by I cannot be received on indicator I5. However, during the next half of the cycle of the current supplied at I8, the plates of the tubes in the transmitter I become negative, rendering this unit inoperative while the plate of the tube 8 becomes positive allowing this tube to pass on any signal coming in on the grid of this tube. When the plate of the tube 8 is positive, the grid is made sufiiciently negative by means of the battery I6 and the position of slider I! on the resistor 1. Thus, during every alternate half-cycle of the voltage supplied at I8, the transmitter I operates and the receiver 9 is dead and during the intermediate alternate half-cycle the transmitter I is dead and the receiver 9 is functioning. By means of the directive antenna I3 which is rotatable about a vertical axis, the direction 01' the signal being received by 9 may be determined by manually rotating it to determine the position for a maximum signal.
With this arrangement, therefore, a mobile object may send a continuous signal of a note depending upon the frequency of the current supplied at I8, which signal will be detected by a second mobile object in the neighborhood, while at the same time the directional receiver on the first mobile object functions continuously to detect the signal sent from the second mobile object. As there are no synchronizing means between the transmitters on the various mobile obiects and difierent frequencies may be used at I8, the receiver 9 will always be intermittently operating during some portion of the cycle of transmission of other transmitters.
during that half-cycle of the igure 2 illustrates another form of my invenas applied to an aircraft. Here l8 repreas the aircraft; 2 and 3 the vertical doublet ennas for transmitting the warning signal in horizontal directions. l3 represents the ditional receiving antenna rotatable about a tical axis and collapsible into the wing as wn at 20. 4 and 5 represent the transmis- 1 lines, I the transmitting set, and 9 the reving set. igure 3 shows an application of my invention era a lower radio frequency is used such as marine use. Here 2| represents a non-direcnal transmitting antenna, 22 is a standard 7 power marine beacon transmitter such as are nmonly used, 6 is a center tap transformer one le of the secondary of which supplies. plate itage to the tube 23 of the transmitter 22 and e other side In supplying plate voltage to the st tube or two tubes in a direction finder reiving set 24. 25 is a direction finder coil rotable about a vertical axis. These circuits nction as explained under Figure 1, except at lower radio frequency. While the above are forms of my invention, is understood that other means of applying the )ltage from transformer 6 to the receiving set my be used to render it operative and then ioperative. Therefore, I do not wish to be limed to these specific embodiments, since modificaions may be made both in the circuits and aparatus within the scope oi! my invention.
Among such modifications would be the inclusion of an audible signal device in the output of tube 8.
What I claim is:
1. In a radiant energy system for indicating the close proximity of one craft to another craft, means carried by each of said craft for transmitting vertically polarized radiant energy of a preselected wave length from each of said craft in all azimuthal ried by each of said craft for directionally receiving the vertically polarized radiant energy of preselected wavelength transmitted from other craft, switching means carried by each of said craft for alternately putting into operation the transmitting means and the receiving means carried by said craft, and means for operating the switching means carried by ferent frequencies, whereby the receiving means carried by each of said craft will be cyclically put into operation during a part oi! the time the transmitting means carried by any and all other craft is energized.
2. A system as set forth in claim 1 in which the wave length of the energy transmitted is small iii-comparison to at least one physical dimension of the craft carrying the means for transmitting vertically polarized radiant energy.
FRANCIS W. DUNMORE.
directions in space, means car- 1 each of said craft at dif-