US1900283A - Selective radio reception - Google Patents

Description

I M 9 -v .1. H HAMMOND, JR

SELECTIVE RADIQ RECEPTION s Sheet-Sheet 1 Filed Nov. 9, 1929 N wm $4 AA AA INVENTOR JOHN HAYS HAMMOND JR. BY 7 Y WPW ATTORNEY March 7, 1933. J H HAMMOND, JR 1,900,283

SELECTIVE RADIO RECEPTION Filed Nov. 9, 1929 6 Sheets-Sheet 2 JOHN HAYS HAMMOND JR.

ATTORNEY March 7,1933. HAMMOND JR 1,900,283

SELECTIVE RADIO'RECEPTION Filed Nov. 9, 1929 6 Sheets-Sheet 3 %I s1 v $1 INVENTOR JUHN HAYS HAMMOND JR ATTORNEY Mairch 1933- J. H. HAMMOND, JR 1, 2

SELECTIVE RAD I O RECEPTION Filed Nov. 9, 1929 e Sh eetS-Sheet 4 INVENTOR 1mm HAYS HAMMOND m.

ATTORNEY March 1933- J. H. HAMMOND, JR

SELECTIVE RADIO RECEPTION Filed Nov. 9, 1929 6 Sheets-Sheet 5 wk C ww w INVENTOR JORN HAYS HMMOND JR.

ATTORNEY March 7, 1933. J. H. HAMMOND, JR

SELECTIVE RADIO RECEPTION Filed Nov. 9, 1929 6 Sheets-Sheet 6 L I f f is (i Patented Mar. 7, 1933 PATENT OFFICE JOHN HAYS HAMMOND, .13., F GLOUCESTER, MASSACHUSETTS snrnc'rrvn RADIO RECEPTION Application filed November 9, 1929. Serial No. 405,874.

The object of this invention is to supply an improved type of selective system for radio communication.

It is a further object to obtain selectivity by the utilization of the spacial distribution of energy in radio transmission. These and other objects will become apparent from the following specification taken in connection with the appended drawings.

A common feature of systems based on this invention is the spacial distribution of energy representative of a transmitted signal, and a receiver gathering energy from different locations in a spacial sense. The spacial distribution of energy changes with time, and it is a property of the receiving system that only when the spacial distribution changes in a proper manner with respect to time will the receiver system be operated to give a signal. In accomplishing this invention, an antenna in the form of a transmission line,

several wave lengths long, is provided pointing in the general direction of the desired reception. At various intervals along the antenna, pick-up points are provided at which the energy existing in the antenna at said points is taken from the antenna. The energy thus picked up by the various pick-up points is transmitted by land line to a central 0 station where it is combined. The energy of the desired signal is arranged to combine in the proper phase while the energy of the undesired signal will not combine into a proper phase, and therefore, a greater degree of selectivity is obtained.

Having thus briefly described my invention, attention is invited to the accompanying drawings in which:

Fig. 1 is a diagram illustrating the principle of the present invention.

Fig. 2 is a d'agram showing a. receiver for carrying out the present invention.

Fig. 3 is a modification of the receiver em- V bodying my invention in which a dummy antenna of the required length is substituted for the actual antenna inFig. 2.

Fig. 4 is a diagram showing the combining circuit for use in the central receiver of either Figs. 2 or 3.

Fig. 5 is a modification of the combining circuit shown in Fig. 4 providing for shifting of the audio frequency phase.

Fig. 6 is another combining circuit arranged to reduce the noise level efiects and utilize two beat type receivers. I

Fig. 7 is a diagram illustrating the wave distribution in the antenna when two incoming waves are present.

Fig. 8 is a diagram illustrating the wave distribution along an antenna when there are two waves present, one locally produced and one being received from the transmitter.

Fig. 9 is a diagram showing the wave distribution for three phase reception.

Fig. 10 is a circuit for utilizing the distribution as shown in Fig. 8 for phase opposition of modulation.

Fig. 11 is a circuit for utilizing 90 phase difference of modulation.

Having thus briefly described the figures embodying my invention, particular attention is now invited to Fig. 1, which shows an illustrative arrangement of the system embodying my invention, in which there is an antenna 10, and a counterpoise 11'of a length equal to several wave lengths of the radiations employed. The counterpoise and antenna are connected together at each end through resistances 12, which act as terminal absorbers. The structure thus composed possesses the properties of a transmission line. Ifthe signals proceed from left to right in Fig. 1,voltages represented by the curve 1 will exist across the antenna and counterpoise.

With a certain continuous wave coming upon the line from the transmitter, when a final steady state is reached there will be at any instant, voltagesacross the transmission line of different phase and magnitude at different points. In particular at points A and B, at the same instant of time the voltages may be opposed, with their. magnitude somewhat different. If now the frequency of thetransmitted wave is changed to another value or a wave of different frequency is received, the phase difference of the voltage at points A and B for that frequency will, in general, not be inv opposition or of 0 180, but of some other value. 1

For example, with a continuous wave frequency of 10,000,000 cycles per second and a propagation velocity along the line 3 X 10 centimeters per second, at any instant of time the phase distribution along the line will change by 360 electrical degrees in 30 meters of distance. Assume for example that A and B are separated 615 meters,'so that there is a total phase difference of 7380 electrical de rees for the 10,000,000 cycle wave, corresponding to 41 half wave lengths. This actuates pick-up systems at A and B in precisely the same manner as though the phase difference were 180. degrees. Now let the frequency be altered slightly, say by onetenth of a percent, then the alteration of phases does not become .1 of 1 percent of 180, but .1 of 1 percent of 7380 or 7.38 electrical degrees. Thus the use of a long transmission line permits a large change of phase for a small percentage change in frequency. 7 It is evident that for a large enough change of frequency, the number of half wave lengths will change by an integral number, so that for example, a phase difference of 180 degrees would exist for about 10,500,000 or for about 9,500,000 cycles. Waves so far separated in frequency may however be prevented from interfering with the performance of the system by simple tuning or band filtering methods.

A further understanding of the invention may be reached by consideration of the asrangement of Fig. 2 to which attention is now invited.

The antenna 10 and counterpoise l1 and resistances 12 are the same as those shown in Fig. 1 except that the center point of the resistors 12 are grounded at 13 as shown. Push- pull amplifiers 21, 22 and 23 are provided for amplifying the energy picked up at the points A, B and C respectively.

Here the voltage pick-up from the antenna 10 is shown from three points, A, B, C, at different locations on the transmission line, and the energy is transmitted to a central station 14 by suitable auxiliary transmission lines 15 and 16. For a wave originating at A, the distance to the central station 14 direct through the amplifier 21 differs from thedistance to central station through amplifier 22 by the distance A to B, wherefore the 1 phase differences at the central station 14 will be the same as between point A and B. When other points of pick-up are used as at C, if desired a line or artificial line 17 from C to the central station 14 may be used equal in effective length to the distance from A or B to the central station.

In place of an actual transmission line type antenna, the energy may be received in any type of antenna system, and impressed upon an artificial line with suitable design, such that the electrical phase shift per section of the artificial line is a different value for different frequencies. Such a line possesses the advantage of smaller space required for the equipment, since by a lumped inductance and a lumped capacity, the phase difierence per section can be made the same as for a length of transmission line equal to nearly ahalf wave length. Such an arrangement is shown in Fig. 3, in which the energy is received by the antenna system and amplified by the amplifier 31 and put into the artificial line, with pick-off circuits 32, 33 and 34 to a common receiving system 35.

It is evident that the feature in common between Figs. 2 and 3 is a method of producing voltages from an incoming signal from different points in space, and leading them into a common receiving system. Further the number of pick-up points may. be as many as desired, and the terminals may be utilized in any number of ways.

One mode of utilization of the various channels produced from a given signal is shown in Fig. 4. This circuit may be used in connection with either Fig. 2 or Fig. 3.

For this figure it is assumed that points A, B andC, have been chosen in such a manner that all voltages of the desired frequency are in phase. Leads 43, 44, and 45 from individual pick-up points are brought to gridfilament branch of combining tubes 40, 41 and 42 respectively, but the plate circuits of the combining tubes are in parallel with a common output inductance 46 inductively related to a second inductance 47 in the input of a usual type radio amplifier and receiver and indicator. In this manner, the desired signals are built up in strength much more rapidly than undesired signals, because the desired signals of equal phase add on a voltage basis, whereas interferences being of random phases combine on an energy basis.

The central station may contain phase shifting devices whereby the phases of the desired signals may be correctly lined up previous to combining. This modification is shown in Fig. 5 in which the terminals 50, 51 and 52 go to individual amplifiers as shown, each operating into a phase shifter 56 of well-known construction. The outputs of the phase shifters are impressed upon the grid circuits of the combining tubes 57, through a suitable arrangement for controlling volume such as the potentiometers 58. The output of the combining tubes is the same as in Fig. 4.

Thus the utilization systems shown above involve the idea of combining the plurality of desired voltages from various pick-up points in the most advantageous manner, for the purpose of building up the desired signal in a much more efficient manner than the in, terfering signals will be built up.

Another utilization method for the reception of continuous wave signals, which method involves the reduction of noise level efiects, is shown in Fig. 6. In this arrangement three pick-up points may be used with adjustments made so that voltages due to the desired signal at A and B are made equal but oppositely phased.

Referring now more particularly to Fig. 6, the inputs from the three pick-up points are indicated at 60, 61 and 62 which go to individual amplifiers 68, 64 and 65 in the same manner as in Fig. 5. The outputs of each of these amplifiers operates into a phase shifting circuit 66 and the intensity of the output is regulated by the potentiometers 68 and fed to amplifier devices 67, 67 and 67 The outputs from 67 and 67are representative of the voltages at points A and B respectively, and are combined out of phase with respect to the desired signal in the inductance 69. Two heat type receivers and 71 are provided, the former of which is supplied by the inductance 69 and the latter of which is supplied by the output of the amplifier 67 representative of the energy at the point C. These two receivers are both supplied with a common heterodyning frequency by the source .72. The receiver 70 will thus receive only the interference, the signal having been balanced out, and the receiver 71 will receive the interference and the signal.

The output of each of the receivers 70 and 71 is fed to a rectifier 72 and 7 3 respectively, of the power type. In the power circuit of each'of the rectifiers there are resistors 74;, which resistors are connected in series with each other and with the coil 75 of relay 76.

The receivers thus operate in well-known manner to produce audio currents, and stray interference noises. These are rectified by power type rectifiers. The rectified outputs of each channel are balanced against each other, and adjustments made such that with no incoming signal the rectified currents due to stray disturbances will completely cancel.

Then with the incoming signal present there will be an increase of rectified current through one channel overthat in the other channel, with a difierent potential drop across the resistors carrying the rectified currents. This will cause current to flow through the indicating relay.

In another type of application of this invention, the signals to bereceived may not be continuous waves, but maybe modulated, or otherwise varied, radio waves. Or the modulations may be of so high a frequency that the radiations may be thought of as two or more distinct wave lengths. .In any case, the phase of the beats or modulations will be different at diiferent points on the line.

Fig. 7 for example, shows the transmission line composed of antenna 10 and counterpoise 11 as in Fig. 1, the curve 7 7 representing the voltages at the various points with two continuous waves from a transmitter. The pick off points A and B are'chosen to be in phase opposition of modulation. 7 Further in place of two incoming continuous wave signals, it may be desirable to use butone incoming signal, and a local oscillator, in which case a modulated distribution will occur along the line, the same as though two waves were radiated from the transmitter. Fig. 8 shows a curve similar to curve 77 of Fig. 7 representative of this condition.

In either case, points can be chosen with definite phase relation of the modulation cycle, as for example such that 180 phase difierence will exist in the modulation, and therefore 180 difference in the-current produced when the radio signals are subj ected to detection. 7

In a still further arrangement, three points might be used, with 120 difference of phase in the modulation, as shown in Fig; 9, in which curve is the same as curve 77 of Fig. 7 and the points A, B and C are 120.

from each other with respect to the phase of modulation.

Two points with 90 phase difference, or a plurality of points with 90 phase difference may also be used.

As numerical example, with a propagation velocity of 3 X 10 centimeters and an incoming signal of 30 meters or 10,000,000 cycles, and a heterodyning signal of 9,500,000

cycles togive an intermediate frequency of 500,000 cycles, the modulation pattern will be recurrent in 19 of the 9,500,000 cycle wave lengths, or 20 of the 10,000,000 cycle wave lengths, that is in 600 meters of line. Or for 10,000,000 cycles incoming signal, and 8,000,- 000 cycles heterodyne, the modulation pat tern will be recurrent in five of the 10,000,000 cycle wave lengths, and'four of the 8,000,000 cycle wave lengths, that is in 150 meters of line; or with suitable artificial line, in the latter case the modulation pattern will be recurrent in ten to fifteen sections.

A circuit for utilizing phase opposition of modulation as in Fig.8, is shown in Fig. 10 to which attention is now invited. Here the pick-off points A and B lead to individual push-pull detectors 81 and 82 respectively, by non-oscillating beat detection, since the heat wave has been transmitted from the recording station, or has been produced on the transmission line by combininga local oscillator with the incoming signal. The detected currents are subsequently selected as for example by tuned circuits 83 and 84. Due to the difference of modulation phase, the se lected currents will be in phase opposition, and may be combined for further utilization by reversed or differential couplings as shown. Subsequent to combining the signals may be reduced to audibility by means of a second order detector 85 and separate heterodyne 72.

It is to be understood that several additional pick-up points may be used to improve the ratio of building up of signals to the ratio of building up of stray interferences. Further the type of receiver may be altered in many ways, such as by insertion of amplifiers, etc.

Attention is now particularly invited to Fig. 11 which shows a circuit for utilizing a 90 phase difference of modulation. Here the curve 80 represents the heat wave form produced by the incoming signal or the heterodyning of the incoming wave and a local frequency. There are shown 8 pick-up points each of which has an individual high frequency amplifier and detector 91, to produce currents of the difference of the incoming and locally supplied high frequency or in other words, the intermediate frequency. The output of the detectors and amplifiers 91 is picked up by the pick-up inductances 92, 93, 94 and 95 in such a manner that inductances 92 and 93 are arranged in series, the latter being reversed to supply the input of the second detector 96 and the inductances 94 and 95, the latter of which are reversed to the former, are connected in series and are adapted to supply the input of the second detector 98. The detectors 96 and 98 are of the beat frequency type, being supplied by the common heterodyning source 97. As a result, a low frequently two phase current is produced in the outputs 99 and 100. Each of the two phases existing in 99 and 100 is led to the appropriate windings of a two phased relay shown generally at 101, which is similar to a two phase induction motor with an armature 102 which moves only when two phases are present. Thus when the proper two phase current exists in the windings of the relay 101, or in other words, when the incoming signal is present, the armature 102 will be oscillated to close the contacts 103 and 104 and thus operate a receiving circuit. In this manner the relay is operated when an incoming signal is present and through the combined use of spacial distribution and intermediate frequency tuning and two phase relay operation, and an extremely high degree of selectivity is obtained.

Having thus described the various forms or embodiments of my invention as well as their operation, attention is invited to the fact that a great many modifications may be suggested which fall into the scope of this invention. Therefore, it is to be understood that I am not to be limited by the specific embodiments shown and described for the purpose of illustration only but by the scope of the invention as defined in the appended claims.

What I claim is:

1. The method of radio reception which includes producing a spacial distribution of the energy representative of a radio signal within a closed path, and combining the energy thus distributed along points of the path where the signal is in the proper phase when of the desired frequency, and not in phase when of an undesired frequency.

2'. The method of radio reception which includes distributing the energy representative of a radio signal along a closed path in such a manner that various phases of the frequencies of which said frequency is composed are available, and combining the energy thus distributed from several points along said path in such a manner that signals of the desired frequency will be in phase, and signals of undesired frequency will be not in phase.

3. The method of radio reception which includes analyzing the voltages produced by a signal being received along a closed path, and combining the voltages thus analyzed as derived from several points along said path to be in phase when of the desired frequency representative of the desired signal, and to be not in phase when of an undesired signal.

4. The method of continuous wave reception which includes heterodyning the incoming signals to produce a modulated wave, distributing the energy representative of said modulated wave in a spacial manner, picking up energy representative of the various phases of modulation of said modulated wave thus distributed, amplifying and detecting said energy to produce a plurality of currents of a frequency equal to the difference of the local and incoming signals, combining energies of the same phase to produce polyphase sources of the difference frequency, generating a lower frequency, detecting each phase of said produced polyphase difference frequency by heat detection with said lower frequency to produce a lower frequency polyphase current, and operating an indicating device by said last mentioned current.

5. The method of continuous wavereception which includes heterodyning the incoming signals to produce a modulated wave of a high order of frequency, distributing the energy representative of said modulated wave in a spacial manner, picking up energy representative of the various phases of modulation of said modulated wave thus distributed, amplifying and detecting said energy to produce a plurality of currents of a frequency equal to the difference of the local and incoming signals, combining energies of the same phase to produce polyphase sources of the difference frequency, generating a lower frequency, and detecting each phase of said produced polyphase difference frequency by beat detection with said lower frequency to produce a low frequency polyphase current.

6. The method of continuous wave reception which includes locallyheterodyning the incoming signalsto produce a modulated wave, analyzing the energy representative of said modulated wave, combining energy representative of the various phases of modulation of said modulated wave thus analyzed, amplifying and detecting said energy to produce a plurality of currents of a frequency equal to the difference of the local and incoming signals, combining the energies of the same phase to produce polyphase currents of the "difference frequency, detecting each phase of said produced polyphase dif ference frequency by beat detection to produce a lower frequency polyphase current, and operating an indicating device by said last mentioned current.

7. The method of high frequency modulated continuous wave reception which includes distributing the energy representative of said modulated wave in a spacial manner, combining energy representative of the various phases of modulation of said modulated wave thus distributed, amplifying and detecting saidenergy to produce a plurality of currents of a frequency equal to the modulation frequency and representative of the phases thereof, combining the energies of the same phase to produce polyphase sources of difference frequency, generating a lower frequency, detecting each phase of said produced polyphase difierence frequency by beat detection with said lower frequency to produce a lower frequency polyphase current, and operatin an indicating device by said last mentioned? current.

8. The method of continuous wave reception which includes distributing a modulated wave representative of a high frequency carrier and another frequency in a spacial manner, picking up energy representative of the various phases of modulation of said wave,

and thus producing a plurality of currents of the modulation frequency, combining the currents of the same phase, generating a lower frequency, detecting each phase of said modulated energy by heat detection with said lower frequency and thus producing a lower frequency polyphase current and operating an indicating device by said current.

9. In a radio receiver,'means for receiving incoming signal energy comprising an antenna system having an electrical length greater than one wave length of the signal energy desired to be received, means for distributing said incoming energy in a spacial manner, a plurality of means for picking up energy representative of the various phases of the incoming frequency, and means for combining the energy thus picked up in phase when of the desired fre-.

quency, and not in phase when of an undesired frequency. v

10. In a radioreceiver, means for receiving incoming signal energy, means for distributing said incoming energy in a spacial manplurality of means for picking up energy representative of the various phases of the 1ncoming frequency, means for amplifying the energy thus picked up, and means for com ,bining theenergy thus amplified in phase when of the desired frequency, and: not in phase when of an undesired frequency.

l1. Ina radio receiver, means for receiv: ing the incoming energy, means for distributing said incoming energy in a spacial manner, a plurality of means for picking up energy representative of the various phases 'of the incoming frequency, means for regulating the intensity of the energy thus picked up, and means for combining the said energy in the proper phase when of the desired frequency, and not in phase when of an undesired frequency comprising a plurality of electron discharge devices having their input circuits connected respectively to said means for pickirig pp energy andtheir output circuits in para le 12. Apparatus for the reception of radiant energy in the form of high frequency modulated continuous frequency comprising means for receiving energy representative of the desired signal, means for distributing the energy representative of said desired signal in a spacial manner, a plurality of pick-up points for tapping energy representative of the desired signal in its variousphases of the modulation frequency, means for amplifying and detecting the energy picked up at each of said points and thus produce a plurality of currents of a frequency equal to the modulation frequency but of different phase, means for combining said currents of the same a common heterodyning source of low frequency energy, means for producing a polyphase current by the heterodyne detec tion of said currentsv representative of the modulation'frequency, and means for operating an indicating device by the polyphase low frequency energy thus produced.

13. Apparatus for the reception of radiant energy including, means for receiving energy phase,

representative of the desired signal, means for distributing the energy representative of said desired signal in a spacial manner, a plurality of pick-up points for tapping energy representative of the desired signal in its means for amplifying and detecting the energy picked up at each of said points and thus produce a plurality of currents of a frequency equal to the modulation frequency but of different phase, means for combining said cura signal. 1:}

various phases of the modulation frequency, 1120 14. In a radio receiver, means for receiving incoming signal energy comprising a multisect-ion artificial line wherein signal energy is intercepted at one end thereof and made to flow along said line, said artificial line having an effective electrical length at least equal to one wave length of the signal energy desired to be received, a plurality of means for picking up energy representative of the various phases of the incoming signal energy along various sections of said line said energy pick-up means being coupled to said line at various points thereof such that the energy picked up thereby is in phase when of the desired frequency and out of phase when of undesired frequency.

JOHN HAYS HAMMOND, JR.

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