US1144969A - Radio telegraphy and telephony receiver. - Google Patents

Description

RADIO TELEGRAPHY AND TELEPHONY RECEIVER. APPLICATION mm APR. 11.1914.

1,144,969 Y 1 PatentedJuneQS), 1915."

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G. W. PICKARD. RADIO TELEGRAPHY AND TELEPHONY RECEIVER. APPLKCATION FILED APR.17,1914.

l 1%% 969@ Patented June 29, 1915.

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RM'BIQ TELEGRAPH? AND TELEPHQNY REGEIVEE.

igiddfiti Specification of letters Patent.

Fatented dune 2%, i915.

application iflflll. April 1.7, 191d. Serial No. 232,592.

To all whom it may concern Be it known that l, Gnnunnnar Wirrrrrnn PICKARI), a citizen of" the United States of America. and a resident of the town of Ameshury, State of Massachusetts, have invented certain new and useful Improvements in Radio Telegraphy and Telephony Receivers, the principles of which are set forth in the following specification and accompanying drawings, which disclose the form of the invention which I now consider to he the best of the various forms in which the princinlcs of the invention may be embodied.

This invention relates to a system or method of receiving intelligence communintcd by electromagnetic waves, the object being a more ellicient system of this kind, the invention consisting; of the apparatus and methods herein disclosed.

Of the drawings, Figures 1 and 2 are explanatory diagrams; Figs. 37 inclusive are diagrammatic illustrations of several of the various useful embodiments of the invention.

The description will be in terms of receipt of continuous or undamped waves with which the invention is most eflicient.

A simple embodiment is shown in Fig. 3 wherein the natural period of the antenna- ,rzround connection A, L, G, the natural period of the closed resonant circuit C U, and the coupling of these two circuits (variable-as indicated by the double arrows) are such, that two oscillating currents of frequencies, which differ from each other, are set up in this svstem when the same is affectcd by transmitted electromagnetic waves which are not materially damped. These two frequencies act together to form heats, which have a lower order of frequency as a,

Z), c. in Fig. 1. the energy periodically rising and falling as indicated. Thus if the oscillating current frequency in one of the above-specified circuits of Fig. 3 is of the order of several tens of thousands per sec-' 0nd. and if the frequency of the other is of a like order but slightly lower. then the heat-frcqucncv mav correspond with that of audible sounds. This heat-frequency. even when caused to be such as to correspond with sound frequencies within the limits of audihilitv, will not of itself produce audible sounds in the electromagnetic telephone receivers T (Fig. 3) for the reason that each I in Fig.

beat comprises a group of oscillations of the much higher frequency 2'. c. of the order of several tens of thousands per second, which is far beyond the limits of audibility, and which would not properly operate such a direct current instrument as such telephones. in order to convert the energy of these heats into sound waves of audible frequency, 2'. e. first, in order to cause it to assume such form as will eliectively operate the telc phones. the heat oscillations are rectified (if-lg. 3) by the connection of the rectifier l) to the coil if (that is, to that part of this coil which extends to the right beyond the connection to it of antenna A). This rectifying device B may he of any suitable hind, such for example, as the well-known types of crystal rectifier or gas rectifier heretofore used in this art, as detectors. The resulting: rectified pulses which operate the telephones 'l are indicated in Fig. 2 at 11. 71, c Thus we have, first, the original frequency of the undamped electromagnetic waves as N transmitted through the ether and received at a given receiving station;

second, we have at that rcceiviug'station an arrangement of circuits such as those shown 3 at A, L, G, and at L whereby said original frequency is converted into two slightly different frequencies (say N and N which produce heats indicated in Fig. 17 and third. w have a means, such as rectiher D (Fig. 3) whereby the beat oscillations are rectified so as to obtain the energy; in most eliicient form to operate the telephones T and produce an audible com munication which has a pitch corresponding with the frequency of the beats. To explain the invention in greater detail. assume that the two principal circuits of Fig. 3 (2'. c. the antenna-ground circuit and the closed resonant circuit L. U) each has the same natural period N due to its capacity, inductance and resistance, this period being the same as that of the trans mitted waves: and assuming further that the coupling of these two circuitshas a coefficient K. It is well known that in such a system two oscillating currents will be set up of frequencies diiiering from each other, frequency N being e ual to N divided by the square root of l plus one, and frequency N being equal to N divided by the square root of one minus K. -According to my observation, these two frequencies N ice and N approach to the common period N in proportion as the coupling of the two circuits in the system is made loose and the period of the resulting beats is so low as to be below the lower limit of audibility. But reversely, as the coupling is made tighter, these two frequencies more widely differ, with the result that the produced beats have a higher frequency. In accordance with this invention, a coupling is em ployed which causes the production of beats which are of not too high frequency or too low frequency to be outside the limits of audibility. When the coupling is too loose,

the current resultingin the telephones from the rectified oscillations of the beats of low frequency corresponding to such loose coupling, will be a smooth, continuous current which fails to operate the telephones to produce an audible sound. .Under this condition a tightening of the adjustable coupling between the coils L and L (Fig. 3) results in an increase of the beat-frequency so that when ,the proper adjustment of coupling is obtained, the formal continuous current in the telephone windings will begin to pulsate; and as the beat-frequency rises above the lower limit of audibility, the" telephones T, receiving the rectified current from instrument D, willemit notes corresponding to the frequency of the beats.

This method is efiicient for working with undamped waves produced by the well known transmitters of such waves, such as those including an are, or an alternator of the frequency of the order of tens of thousands. The method can also be used, however, with spark transmitters, particularly those having slight damping.

Fig; 4-diifers from Fig. 3 in having an inductive relation of the circuit DT with the coil L by way of the coil'L and in having this circuit grounded. as shownyat G. In any case where such an inductive relation is employed, the coupling between coils L and L may be varied or adjusted if desired. In Fig. 5 also the relation of circuit DT is inductive to coil If by way of coil L", but circuit DT is not mounted as in Fig. 4, and is provided with a'battervpotentiometer circuit B-P. In Fig. .6 the coil L is conductively related to coil L by way of rectifier D and by the circuit of the telephones T, battery B and potentiometer coil P.- In all of Figs. 36 inclusive, the connection of the circuits DT and the inductance coil or coils is uni-lateral, this connection being'made in Fig. 3 to the right hand end of coil L, i. e. the part extending to the right beyond the connection thereto of antenna A; in- Figs. 4 and 5 thisconnection is made to one end of coil L and-in Fig. 6'this connection is made between the right hand end of coil L and the left hand end of the open-circuited coil L. In Fig.

7, however, the method is employed in a system involving a closed circuit cooperating with the antenna coil L in the open circuit A, L, G, which is preferably, adjusted to the periods of the transmitted waves. Here circuit C, L itself is adjusted to the same frequency, but has a variable coupling with coil L If this coupling is of the proper degree -of tightness, as above explained, the beat-frequency set up will be sufliciently high to be within the limits of audibility. The coil L", here as in the other figures, is a pick-up coil for the beat-pulses, and this coil passes said pulses on to the rectifier D which converts the oscillations composing each heat into the proper form to operate telephones T. In this case, however, the circuit of the pick-up coil is not open and is closed through condenser C and this circuit may, if desired, have the same natural period as those of the circuits of the coils I and L obtained as by adjustment of coil L or condenser C or both. Here this circuit L, C is shunted by the rectifier-telephone circuit DT wherein the telephones are shunted by the condenser C.

In Figs. 4, 5, and 6, the coil L corresponds with the pick-up coil L of Fig. 7, and in Fig. 3 the coil socorresponding is the right hand part of coil L which extends beyond the connection of antenna A.

As indicated above, the general system and method of this invention is more efficient in proportion as the transmitted waves are substantially undamped, being most efiicient with the continued or undamped waves which are emitted from a transmitter employing an are or an alternator of the high frequency hereinbefore specified. However, the method is also useful in receiving waves which are radiated from transmitters including a spark gap provided that such waves are not too highly damped.

I claim: 1. In a system of communicating intelli- 'gence by electromagnetic waves which are not materially damped, the combination, at a receiving station, with means for causing such waves of a given frequency to set up oscillating currents of two frequencies differing from each other to such extent as to produce beats of audible frequency, of means for causing the energy of said beats to produce a sound of a pitch corresponding to the frequency of the beats.

2. In a system of communicating intelli gence by electromagnetic waves which are not materially damped, the combination, at a receiving station, with means for causing such waves of a given frequency to set up oscillating currents of two frequencies differing from each other to such extent as to produce beats of audible frequency, of means for rectifying the oscillations composing said beats, and a telephonic device menace operable by the rectifiedbeat-pulses to pro duce a sound having a pitch corresponding to the beat-frequency.

3. In a svsteni of communicating intelligence by electromagnetic waves which are not materially damped, the combination, at a receiving station, with two resonant circuits having such periods and coupling as to cause such waves of a given frequency to set up oscillating currents of two frequencies differing from each other to such extent as to produce beats of audible frequency; of a pick-up coil arranged to receive said beat-pulses; means for rectifying the oscillations composing said beats; and a telephonic device operable by the rectified beat-pulses to produce a sound having a pitch corresponding to the beat-frequency.

4; In a system of communicating intelligence by electromagnetic waves which are not materially damped, the combination, at a receiving station, with two resonant circuits having such periods and coupling as to cause such Waves of a given frequency to set up oscillating currents of two frequencies differing fromeach other to such extent as to produce beats of audible frequency;

of a pick-up coil arranged to receive said beat-pulses; of means for causing the energy of said beats to produce a sound having a pitch corresponding to the frequency of the heats. v

5. In a system of communicatin intelligence by electromagnetic waves w ich are not materially damped, the combination, at a receiving station, with means for causing such waves of a given frequency to set up oscillating currents of two frequencies differing from each other to such extent as to produce beats of audible frequency, of a pick-up coil arranged to receive said beatpulses; and means unilaterally connected to said pick-up coil, and operable by the energy of said beat-pulses, to produce a sound having a pitch corresponding with the frequency of the beats.

GREENLEAF WHIITIER PICKARD. Witnesses:

M. C. HANNON, W. F. BARKLEY.

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