US2571640A - Supersonic whistle for code communication - Google Patents

Description

Oct. 16, 1951 R. c. WILLMAN 2,571,640

SUPERSONIC WHISTLE FOR CODE COMMUNICATIONS Filed May 12, 1 945 INVENTOR. Flew/120 C Mum/w A TTORNEY Patented Oct. 16, 1951 SUPERSONIC WHISTLE FOR CODE COMMUNICATION Richard C. Willman, Indianapolis, Ind., assignor to Radio Corporation of America, a corporation of Delaware Application May 12, 1945, Serial No. 593,500

7 Claims.

tain a more uniform air pressure applied to the whistle, therefore keeping the output frequency more nearly constant.

A feature of this invention is the arrangement of a whistle with an improved mouthpiece having a relief valve attached thereto.

Supersonic code communication equipment generally includes a small whistle which is blown by the mouth and tuned to any frequency between 15 and 26 kilocycles per second. A sharply tuned receiver which is tuned to the same frequency as the whistle is used to receive the code communication. The receiver usually employs an oscillator which is arranged to beat With the supersonic frequency to produce an audible signal. It has been found that the output signal frequency from the whistle varied so greatly with the air pressure that it was difficult to blow the whistle so thatits output would be received properly by the sharpl tuned receiver. This invention overcomes the difliculty by maintaining more uniform air pressure by providing an improved mouthpiece having a relief valve associated therewith.

This invention will best be understood by referring to the accompanying drawing in which:

Fig. 1 is a longitudinal section of the whistle of this invention, and

Fig. 2 is a cross section of Fig. 1, the section being taken on line 22.

Referring now in detail to the drawing, the body portion of the whistle includes a long cylindrical member I, which may be constructed of metal. At a suitable portion along the length of member I, there is provided an aperture 2 which is tapered at 3 to provide a sharp edge at portion 4. The length of the resonant air chamber between the end plug 5 and. a rod member 6 is determined by the frequency at which the whistle is to operate. The rod shaped portion 6 is secured to the inner wall of member I, the upper portion being cut away to provide an air passage or chamber I. A mouthpiece 8 is shaped at S to receive the outer portion of body I and the forward end is suitably shaped at In to form the usual mouthpiece. Intermediate the portions 9 and I0, there is located a slotted portion I I and a flattened portion I2. Surrounding the portions II and I2, a thin Phosphor bronze spring I3 is suitably shaped to be located with the portions II and I2 and held by its own tension over a relief valve hole I4. The tension of spring I3 is adjusted to open at any predetermined desired pressure. Inthe operation of this device when it is desired to transmit code signals the mouth piece In of the whistle is placed in the mouth and the operator blows a jet of air through the air passage I which impinges the knife edge 4 causing a supersonic frequency wave to be emitted from the resonant air chamber. If the operator should blow the whistle too hard or with an uneven pressure the spring tension relief valve l3 will open until the pressure is reduced.

In a device which was constructed, a half pound per square inch pressure was chosen. As long as the whistle is blown hard enough to open the spring, the pressure on the whistle will not be appreciably above one-half pound per square inch.

The size of aperture I4 is sufliciently large to accomplish this when the unit is blown by any air pressure capable of being created by lung power. The vibration of the spring I 3 when opened tends to impart a warble to the emitted signal which is desirable for this type of code application. The sound of the escaping air can be silenced by the addition of layers of absorbing material over a plurality of escape holes of apertures I5, l6 and H which are provided on the metallic cover ring member I8.

What is claimed is:

1. A structure for producing substantially constant frequency compressional waves in response to continuous application of a fluid varying in pressure over a wide range of pressures, including a hollow bOdy portion having fluid inlet and outlet apertures and an orifice located between said apertures, and a resilient member subjected to the flow of said fluid and positioned with respect to said orifice to form a closurefor the same, said resilient member effectively adjusting said orifice to bypass a portion of said fluid to maintain substantially constant pressure at said outlet aperture.

2. A structure for producing substantially constant frequency compressional waves in response to continuous application of a fluid varying in pressure over a wide range of pressures, including a hollow body having a resonant chamber, said chamber having fluid inlet and outlet apertures and an orifice located between said apertures, and a resilient member subjected to the flow of said fluid and positioned with respect to said orifice to form an adjustable closure for the same, said resilient member being effective to open and close said orifice to bypass a portion of said fluid to maintain substantially constant pressure at said outlet aperture.

3. A structure for producing substantially constant frequency compressional waves in response to continuous application of a fluid varying in pressure over a wide range of pressures, including a body portion having a resonant chamber having fluid inlet and outlet apertures leading into and out of said chamber, a mouthpiece having a bore adapted to communicate with said fluid inlet, and an orifice leading from said bore to the exterior of said mouthpiece, and a resilient member arranged internally of said mouthpiece and subjected to the flow of said fluid, said resilient member being positioned with respect to said orifice to form an adjustable closure for the same, said resilient member being adjusted effectively to bypass all of said fluid above a predetermined amount to maintain substantially 4 constant pressure at said outlet aperture.

4. A generator for producing substantially constant frequency compressional waves in response to continuous application of a fluid varying in pressure over a wide range of pressures, including a body portion comprising a hollow tube having one end closed and an outlet aperture, said tube having the dimensions between said closed end and said outlet aperture to provide resonance at the desired frequency, a mouthpiece connected to the open end of said tube, said mouthpiece having an annular bore therewithin and a relief valve hole leading from said bore to the exterior, and a spring tensioned valve member positioned in said bore to cover said relief valv hole, said spring tensioned valve member being adjusted to bypass all of said fluid above a predetermined value to maintain substantially constant pressure at said outlet aperture.

5. A structure providing a uniform air pressure front in response to steadily applied air of varying pressure, including a hollow member having an elongated bore therethrough, an annular bore surrounding said elongated bore, said member having a relief valve hole interconnecting said bores, and a relief valve spring arranged in said annular bore to cover said relief valve hole, said spring being adjusted to bypass air applied at one end of said elongated bore above a predetermined value to produce substantially constant pressure at the other end of said elongated bore.

6. A structure providing a uniform air pressure front in response to steadily applied air of varying pressure, including a hollow member having an elongated bore therethrough, an annular bore surrounding said elongated bore, there being a fiat surface in said annular bore, said member having a relief valve hole arranged in said flat surface to interconnect said bores, and a relief valve spring arranged in said annular bore, said relief valve spring having a flat portion arrangedv to cover said relief valve hole, the flattened portion of said spring being arranged to bypass air applied at one end of said elongated bore above a predetermined value to produce substantially constant pressure at the other end of said elongated bore.

'7. A structure providing a uniform air pressure front in response to steadily applied air of varying pressure, including a hollow member having an elongated bore therethrough, an annular bore surrounding said elongated bore there being a flat surface in said annular bore, said member having a relief valve hole arranged in said flat surface to interconnect said bores, and a relief valve spring arranged in. said annular bore. said relief valve spring having a flat portion arranged to cover said relief valve hole, the flattened portion of said spring being arranged to bypass air applied at one end of said elongated bore above a predetermined; value to produce substantially constant pressure at the other end of said elongated bore, and a cover band surrounding said member' to hold said spring in place, said band having escape holes therein to permit escape of the bypassed air.

RICHARD C. WILLMAN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 39,873 Banks Sept. 15, 1863 405,868 Bernardin June 25, 1889 992,487 Ellison May 16, 1911 1,038,074 Berrenberg Sept. 10, 1912 1,225,940 Dixon May 15, 1917 1,315,019 Heyer Sept. 2, 1919 1,779,795 Backstatter Oct. 28, 1930 2,245,484 Leavens. June 10, 1941 2,376,971 Kleit May 29, 1945

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