US1546781A - Method of and apparatus for the reception of radiosignals - Google Patents

Description

July 21, 1925. 1,546,781

C. L. FARRAND METHOD OF AND APPARATUS FOR THE RECEPTION OF RADIOSIGNALS Filed Oct. 15, 1919 2 Sheets-Sheet 1 FIG.2.

INVENTOR 82 13 L. Farrand July 21, 1925. 1,546,781

c. L. FARRAND METHOD OF AND APPARATUS FOR THE RECEPTION OF RADIOSIGNALS 2 Sheets-Shed 2 Filed Oct. 13, 1919 INVENTOR [air Z. Farrah BY MM ATTORNEY I resistance variation differs slightly from the Ulhlllllt I). FARR/AND, @F SQUND BEACH, UUNNEUTEGUT, ASSIGN'O'R 0F ENE-THIRD lfi' attain CQRNELI'US D. lEHltET, @112 M O'UNJE AIMEE, PHIEADELFHIA, FENNSYLVAMA.

innrnon @E AND APPARATUS FOR THE RECEPTIIQN 01 aniolrosreirraris.

Application filed @ctober lml lt Serial 1%. teams.

To all whom it may concern:

Be it known that l, CLAIR L. FARRAND, a citizen of the United States, residing at Sound Beach, Fairfield County, State of Connecticut, have invented a Method of and Apparatus for the Reception of Radiosigrials, of which the following is aspecification.

The object of this invention is to provide methods of and means for the reception of radio telegraphic signals, particularly signals of undamped waves.

My invention depends upon the discoveries, first, that the impedance of a high he quency circuit can be varied at a high frequency rate; second, that the amplitude of the signal current varies at a frequency equivalent to the difference between the frequency of the signal and the frequency of impedance variation when the frequency of frequency of the sig'nal.

My invention, stated broadly, consists in the method of and apparatus for the periodic regulation of amplitude of the high frequency signal current, by means of a pcriodically changing impedance, whereby the regulationof amplitude corresponding in frequency to the difference in frequency between the frequency of the signal and the frequency .of the impedance change is pro-- duced. p

The following is a description of .the method of and apparatus for attaining the above results, and will best be understood by referring to the accompanying drawings,

,wherein the same numerals refer to corresponding parts in all figures.

Fig. 1 shows diagrammatically the method of practicing my lnvention involving a means of regulating the impedance of a secondary circuit of a radio receiver; Fig. 2 shows diagrammaticallthe method of regulating the impedance 0 both primary and secondary circuits of a radio receiver; Fig. 3 shows diagrammatically the same method as Fig. 2, excepting that the impedance is varied for signal current when flowing in both directions; Fig. 4 shows diagrammatically the method involving the mechanical means of varying the coupling co-efiicient between two circuits of a high frequency inductor alternator inconjunction with a detector; Fig. 5 shows diagrammatically the method involving the same mechanical means as Fig. 4, utilizing the low frequency current component of the alternator to actuate the telethree-electrode vacuum valve 11. The grid 13 is interposed-between plate 14: and filament 12, and a high frequency alternating potential is applied from source 17. With some types of valves it is advisable to include a negative potential battery 16 for the grid circuit. It will be understood by those skilled in the art that the resistance of the plate filament circuit of valve 11 is very igh when the grid 13 is negative and will consequently increase the impedance of the receiver circuit 4-5 very slightly; however, as the grid 13 becomes more positive due to the alternation of the potential applied from source 17 the resistance of the plate filament circuit decreases, causing a correspond ing decrease in the impedance of the receiver circuit and producing a corresponding reduction in the amplitude of the signal current flowing therein. Inasmuch as the 1mpedance change of the receiver circu t is effected at. high frequency rate differing slightly in frequency from the frequency of the, signal, the signal current changes in amplitude periodically at a rate corresponding in frequency to the difference between the frequencyof the signal and the frequency of the impedance change. Thls periodically changing current, rectlfied, produces a low frequency current corresponding 1n frequency to the difference between the frequency of the signal and the frequency of the resistance change,

Referring to Fig. 2, the numerals show arts corresponding to Fig. 1. 18 is an inluctance coupled to the primary and secondary circuits of the receiver and connected to the plate filament circuit of the three-electrode valve 11. In this manner the effective impedance of the primary and secondary circuits are changed, producing a signal corresponding in frequency to the difference in frequency between the frequency of the signal and the frequency of the impedance change.

Referring to Fig. 3, the numerals show parts corresponding to Figs. 1 and 2; 19 is a three-electrode vacuum valve comprising 20 the filament, 21 the grid, and 22 the plate, 23 the filament heating battery, and 24 the negative grid battery. The plate 14 of valve 11 and the filament 20 of valve 19 are connected to one terminal of inductance 18; the filament 12 of valve 11 and the plate 22of valve 19 are connected to the other terminal of inductance 18; the sources of alternating potential 17 and 25 are connected to the grids of valve 11 and 19, respectively. These sources of alternating potential 17 and 25 are shown as alternators mounted on a common shaft, but may consist of any common form of oscillation generator. By the means shown in Fig. 3, the impedance of the receiver circuit is regulated for signal currents flowing in both directions.

3 is somewhat higher than that of the arrangement shown in Fig. 2.,

Referring to Fig. 4, the numerals 26. repsuitable form of detector may be used. Due

to the variation of coupling coeflicient between circuit 4526 and circuit 29-30- 5;; at a rate corresponding to the frequency of rotation of the alternator a signal is produced. The current in the detector circuit corresponds in frequency to the difference between the frequency of thesignal, and the frequency of rotation of the alternator. The alternator is shown having eight poles for clearness of illustration. It is assumed that a sufficient number of poles would be usedto'obtain synchronism with the signal at reasonable speed. The inductor type alternator has advantages over the type shown at frequencies of 'the order of fifty thousand cycles per second.- v

Referringxto'Fig. 5, the numerals represent parts corresponding to Fig. 4. The rotor wmding. of the alternator is tuned by The reception efiiclency of the arrangement shown in F ig.

means of inductance 32 and condenser 33 in series with telephone 9 to the difference in frequency between the frequency of the signal and the frequency of rotation of the alternator,

As the broad underlying principle herein disclosed is capable-0f various applications, such as frequency conversion at radio frequencies as Well as at audible frequencies, it is not intended to limit the scope of the invention disclosed and claimed to the figures and apparatus shown and described, but to include therein the variousmodifications ofapparatus and methods capable of periodically regulating the amplitude of the high frequency signal current, such as the periodic extraction of energy by resistance, the periodic change of capacitive reactance, the periodic change of inductive reactance, the periodic change of mutual capacitive or inductive reactance, or the periodic change of coupling coefficient. All of these may be classed generally under, and are intended to be understood as comprehended by, the phrase the periodic change of impedance, as. used in the method. claims hereto appended.

Impedance variation at frequency different from the signal frequency and, more specifically, at audio frequency is claimed in my prior application Serial No. 296,960, filed lVfay 14, 1919. i

Having thus described my invention, I claim:

1. The method of receiving and translating into a signal radio frequency signal-representing energy, which comprises receiving and detecting the signal-representing energy in a circuit whose impedance is always finite, independently varying the impedance of said circuit by 'varying an impedance between finite limits at a frequency above audibility, and translating the current as modified by said impedance variation into a signal.

2. The method of receiving and translating into a signal radio frequency signal-representing energy, whichcomprises receiving and detecting the signal-representing energy in a circuit whose impedance is always finite, independently varying the impedance of said circuit by varying an impedance between finite limits at a high frequency differingfrom the frequency of the signal-representing energy, and translating the current as modified by said impedance variation into a signal.

3. The method of receiving and translating into a signal radio frequency signal-representing energy, which comprises rectify- 1ng the radio frequency signal-representing energy in a circuit whose impedance is always finite, independently varying the impedance of said circuit by varying an im- Ski weaver above audibility, and translating into a signal the rectified current as modified by said impedance variation.

4. The method of receiving and translating into a signal radio frequency signal-representing energy, which comprises rectifying the radio frequency signal-representing energy in a circuit whose impedance is always finite, independently varying the impedance of said circuit by varying an impedance between finite limits at a high frequency differing from the frequency of the signal-representing energy, and translating into a signal the rectified current as modified by saidimpedance variation;

5. The method of receiving and translating into a signal radio frequency signal-representing energy, which comprises impressing the received energy upon the anode cathode circuit of a thermionic impedance, independently varying theimpedanceof said circuit by varying an impedance at a frequency above audibility, and translating into a signal the current in said circuit as modified by said impedance variation.

6. The'method of receiving and translating into a' signal radio frequency signal-representing energy, which comprises impressing the received energy upon the anodecathode circuit'of a thermionic impedance, independently varyingthe impedance of said circuit at a high frequency differing from the radio frequency of the signal-representing energy to impart to the current in said circuit an amplitude variation whose frequency is equal to the difl'erenc'e between said radio and high frequencies, and translating into a signal said amplitude variation of said current.

7. The method of receiving and translating into a signal radio frequency signal-representing energy, which comprises impressing the same upon a circuit including a thermionic impedance, independently varying the impedance of said circuit by varying a second thermionic impedance at a redetermined frequency, and translating nto a signal the current as modified by said. impedance variation.

8. The method of receiving and translating into a signal radio frequency signal-rcpresenting energy, which comprises impressing the same upon a circuit including a thermionic impedance, independently varying the impedance of said circuit by varying a second thermionic impedance at a frequency above audibility, and translating into a signal the current as modified b-y-said impedance variation.

9. The method of-receiving and translating into a signal radio frequency signal-representing energy, which comprises impress? ing the same upon a circuit including a ther- 111101110 impedance, independently varying the impedance of said circuit bv \varving a second thermionic impedance at a high frequency differing from theradio frequency of said signal-representing energy, and translating into a. signal the current as modified by said impedance variation.

10. The method of receiving and translating into .a signal radio frequency signalrepresenting energy, which comprises impressing the same upon a detector, independently varying the operation of said detector by a thermionic impedance varying in magnitude periodically at a frequency above audibility and translating into a signal the current as modified by said impedance variation. K

11. The method of receiving and translating into a signal radio frequency; signalrepresenting energy, which comprises impressing the same upon a thermioni detector, independently varying theoperaEon of said detector by a thermionic impedance varying in magnitude periodically at a frequency above audibility, and translating into a signal the current as modified by said impedance variation.

12. The method of receiving and translating into a signal radio frequency signal-r epresenting energy, which comprises impressing the same upon a detector, independently varying the operation of said detector by .a thermionic impedance varying in magnitude periodically at a'high frequency differing from the radio frequency of saidsigrial-representing energy, and translating into a signal the current as modified by said impedance variation.

13. The method of receiving and translating into a signal radio frequency signalrepresenting energy, which comprises impressing the received energy upon a circuit with which is operatively related a thermionic device comprising an anode, cathode and control electrode, periodically varying the potential of said control electrode independently of the received energy at a frequency above audibility, and translating the resultant impedance variations into an audible signal.

14. The method of receiving and translating radio frequency energy, whichcomprises impressing the received energy upon a circuit withwhich is operatively related a thermionic device comprising an anode,

cathode and control electrode, periodically varying the potential of said control electrode independently of the received energy at a frequency above audibility, and efiect ing current variation by the resultant impedance variations.

15. Receiving apparatus for translating radio frequency current comprising a rectifying detector, means for impressing the received energy thereon, a translating instrument controlled by said detector, means for independently varying the impedance of the detector circuit comprising an associated thermionic impedance, and means for varying the magnitude of said thermionic impedance at a predetermined frequency.

16. Receiving apparatus for translating radio frequency currentcomprising a rectifying detector, means for impressing the received energy thereon, a translating instrument controlled by said detector, means for independently varying the impedance of the detector circuit comprising an associated thermionic impedance, and means for varying the magnitude of said thermionic impedance at a predetermined frequency above audibility.

17. Receiving apparatus for translating radio frequency current comprising a rectifying detector, means, for impressing the received energy thereon, a translating instru- .ment controlled by said detector, means for independently varying the impedance of the detector circuit comprising an associated thermionic impedance, and means for varying the magnitude of said thermionic impedance at a high frequency differing from the radio frequency of the received energy.

18. Receiving apparatus for translating radio frequency current comprising a detector circuit, and means associated therewith for effecting independent impedance variation comprising a thermionic device having an anode, cathode and field-producing means, and means for varying the field produced by said means at a predetermined requency above audibility.

19. Receiving apparatus for translating radio frequency current comprising a detector circuit, and means associated therewith tector circuit, and means associated therefor effecting independent impedance variation comprising a thermionic device having an anode, cathode and field-producing means, and means for varying the field produced by said means at a high frequency difl'ering" from the radio frequency of the received energy.

20. Receiving apparatus for translating radio frequency-current comprising a dewith for effecting independent impedance var atlon compr sing a thermionic device havung an anode, cathode and control electrode, and means for varying the potential of said control electrode at a frequency above audibility.

21. Receiving apparatus for translatingradio frequency current comprising a detector circuit, and means associated therewith for efi'ecting independent impedance variation comprising a thermionic device havin an anode, cathode and control electrode, an means for varying the potential of said control electrodeat a high frequency differing from the radio frequency of the received Receiving apparatus for translating with for effecting independent impedance variation comprising a path including a pair of thermionic devices in parallel with said path and each comp-rising an anode and a cathode, the anode-cathode paths of said thermionic devices being reversely related to said path, field-producing means for each of said thermionic devices, and. means for varying the fields produced by said means at a predetermined frequency.

23. Receiving apparatus for translating radio frequency current comprising a detector circuit, and means associated therewith for effecting independent impedance variation comprising a. path including a pair of thermionic devices in parallel with said path and each comprising an anode and a cathode, the anode-cathode paths of said thermionic devices being reversely related to said path, field-producing means for each of said thermionic devices, and means for varying the field produced by said means at a predetermined frequency above audibility.

24. Receiving apparatus for translating radio frequency current comprising a detector circuit, and means associated'therewith for effecting independent impedance variation comprising a path including a pair of thermionic devices in parallel with said path and each comprising an anode and a cathode, the anode-cathode paths of said thermionic devices being reversely related to said path, field-producing means for each of said thermionic devices, and means for varying the fields produced by said means at a high frequency differing from the radio frequency of the received energy.

25. Receiving apparatus for translating radio frequency current comprising a detector circuit, a second circuit containing a thermionic impedance, a path traversed by the received energy, means 'for coupling said path to said circuits, and means for varying the received energy, means for coupling said path to said circuits and said circults to each other, and means for varying said thermionic impedance at a predetermined frequency. I

27. Receiving apparatus for translating radio frequency current comprising a detector circuit, a second circuit containing a thermionic impedance, a path traversed by the received energy, means for coupling said path to said circuits, and means for varying said thermionic impedance at a predetermined frequency above audibility.

28. Receiving apparatus for translating radio frequency current comprising a detector circuit, a second circuit containing a thermionic impedance, a path traversed by the received energy, means for coupling said path to said circuits and said circuits to each other, and means for varying said thermionic impedance at a predetermined frequency above audibility.

29. Receiving apparatus for translating radio frequency current comprising a detector circuit, a second circuit containing a thermionic impedance, a path traversed by the received energy, means for coupling said path to said circuits, and means for varying said thermionic impedance at ahigh frequency differing from the radio frequency of the received energy.

30. Receiving apparatus for translating radio frequency current comprising a detector circuit, a second circuit containing a thermionic impedance, a path traversed by the received energy, means for coupling said path to said circuits and said circuits to each other, and means for varying said thermionic impedance at a high frequency differing from the radio frequency of the received energy.

31. Receiving apparatus for translating radio frequency current comprising a circuit, a thermionic device operatively related to said circuit and comprising an anode, cathode and control electrode, means for pcriodically varying the potential of'said control electrode at super-audible frequency independently of the received energy, and means controlled by the resultant current.

32. Receiving apparatus for translating radio frequency current comprising a circuit, a thermionic device operatively related to said circuit and comprising an anode, cathode and control electrode, means for periodically varying the potential of said control electrode independently of the received energy at a frequency above audibility, and means for translatingthe resultant current into an audible si a1.

CLAIR L. FARRAND.

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