Satellite and space communications systems

Abstract

1. The method of communicating intelligence by radio waves between at least two bodies in space in motion with respect to each other where a first of said bodies includes an antenna having at least one null orientation with respect to radio waves received from a predetermined direction, said method comprising the steps of: (a) transmitting the intelligence simultaneously via at least two separate radio waves from at least two geographically widely separated transmitting stations on said second body respectively and with said stations having sufficient separation that the two lines of sight from the location of said antenna on said first body to each of said separated transmitting stations on said second body form a finite angle therebetween which exceeds the angular cross section of the antenna null; (b) and responding at said first body in space only to strongest of the several signals received from said transmitting stations on said second body; whereby said antenna on said first body can have at any time a null orientation with respect to, at most, one of said radio waves and said first body thereby continually receives said intelligence from said second body.

Having thus disclosed our invention, what we claim as new and desire to secure by Letters Patent of the United States follows: 
     
       1. The method of communicating intelligence by radio waves between at least two bodies in space in motion with respect to each other where a first of said bodies includes an antenna having at least one null orientation with respect to radio waves received from a predetermined direction, said method comprising the steps of: (a) transmitting the intelligence simultaneously via at least two separate radio waves from at least two geographically widely separated transmitting stations on said second body respectively and with said stations having sufficient separation that the two lines of sight from the location of said antenna on said first body to each of said separated transmitting stations on said second body form a finite angle therebetween which exceeds the angular cross section of the antenna null;   (b) and responding at said first body in space only to strongest of the several signals received from said transmitting stations on said second body; whereby said antenna on said first body can have at any time a null orientation with respect to, at most, one of said radio waves and said first body thereby continually receives said intelligence from said second body.     
     
     
       2. The method of claim 1 in which the intelligence transmitted from one of said transmitting stations is delayed by an amount causing it to be in time and phase coincidence at said first body with the intelligence received on said second body from the other of said stations. 
     
     
       3. The method of claim 1 wherein said two separate radio waves transmitted to said first body are on respectively different nominal carrier frequencies. 
     
     
       4. The method of claim 1 in which the frequency of said radio waves transmitted from the respective transmitting stations on said second body is adjusted by an amount substantially equal and opposite to the amount of Doppler frequency shift produced in said wave as received on said first body. 
     
     
       5. The method of claim 1 in which the same intelligence is transmitted from each of said transmitting stations on each of a plurality of respectively different carrier frequencies all of which are radiated in substantially the same direction toward said first body but which travel over different propagation paths because of the different refractions experienced by the respectively different frequencies, whereby at least one of said carrier frequencies from each said transmitting station is likely to impinge upon said first body. 
     
     
       6. The method of claim 5 in which said first body radiates at least one radio wave which is received by both said stations on said second body, and said plurality of frequencies is radiated from each said station on said second body in the direction of reception of said one wave from said first body even though the line-of-sight direction between said two bodies is constantly changing. 
     
     
       7. The method of communicating signal intelligence to a body in space where said body includes a directional antenna having at least one null orientation with respect to radio signals received from any predetermined direction, the method comprising the steps of: (a) transmitting said intelligence simultaneously in the form of modulated carried radio waves from at least two geographically widely spaced stations whose spacing is sufficient in relation to the distance of said body that said antenna can have a null orientation with respect to at most one of said radio waves;   (b) and responding at said body in space to only the stronger of the waves received from said two transmitting stations.   
     
     
       8. The method of claim 7 including the further steps for transmitting intelligence from said body in space to said transmitting stations which comprises: (a) energizing said antenna with a radio carrier wave modulated according to the intelligence to be transmitted from said body;   (b) responding at each said station to the signal transmitted from said body;   (c) and connecting an output circuit which is common to both said stations to the signal being received at each said station from said body; whereby said output circuit is substantially continuously energized in response to a signal representing the intelligence transmitted from said body in space.     
     
     
       9. The method of claim 7 including the further steps of continuously orienting a transmitting antenna at each said station to maximize the amplitude of the signal transmitted toward said body. 
     
     
       10. The method of communicating intelligence to a space station having an antenna which is at times disposed in a null orientation with respect to a radio wave received from any predetermined direction and comprising the steps of: (a) transmitting simultaneously at least two carrier radio waves each modulated according to the intelligence to be communicated to said space station and with said waves emanating from stations sufficiently widely spaced that said antenna can have a null orientation with respect to at most one of said radio waves;   (b) delaying the modulation on at least one of said carrier waves in accordance with the difference in the respective propagation times of the modulations from their common source to said space station to thereby cause the respective modulations on said waves to be substantially in time coincidence when received at said space station;   (c) and responding at said space station to the stronger of the two carrier waves.   
     
     
       11. In a system for communicating intelligence via radio with a body in space having a directional antenna that may at times be null oriented with respect to a radio beam coming from any particular direction, the combination comprising: first and second transmitting means at geographically widely spaced locations for transmitting carrier waves simultaneously to said body in space with both said waves being modulated substantially simultaneously according to the intelligence to be transmitted to said body, said locations being so far separated that said directional antenna can at any instant have a null orientation with respect to at most one of the radio waves transmitted from said respective first and second transmitting means, receiving means on said body electrically coupled to said directional antenna and producing an output signal only in response to the received carrier wave which produces the greatest amplitude of signal in said directional antenna, and output means connected to said receiving means and being responsive to the demodulated output of said signal produced by said receiving means. 
     
     
       12. The system of claim 11 in which means is coupled to each said transmitting means to vary its frequency in response to the continuously measured component of velocity of said body relative to said transmitting location, whereby the carrier frequency received at said body from any transmitting station is substantially unvarying despite Doppler frequency shifts resulting from the relative velocity between said body and the location of said transmitting station. 
     
     
       13. The combination of claim 11 in which each said station includes at least one antenna for radiating electromagnetic energy to said body in space, and means is coupled to each said radiating antenna to continuously orient said antenna with respect to said body, whereby the maximum amplitude of radio wave is continually received by said antenna on said body from each said station. 
     
     
       14. A system for communicating intelligence between the earth and a space station having an antenna which may at times have a null orientation with respect to radio waves received from any one station on earth, the combination comprising: at least two stations on earth each comprising transmitting and receiving means and being sufficiently widely spaced that said antenna can have at most a null orientation with respect to radio waves originating with one of said stations but still permitting line-of-sight communication between each said earth station and said space station, means at each earth station for modulating a carrier frequency wave transmitted from that station according to the intelligence to be transmitted to said space station, means at said space station including demodulator means responsive only to the strongest of the carrier waves energizing said antenna, modulator means at said space station for modulating a carrier wave according to the intelligence to be transmitted to earth and energizing said antenna with the resulting modulating carrier wave to radiate said wave toward said earth stations, said receiving means including a receiving antenna at each earth station, and means connected electrically to each said receiving means at the respective stations and being responsive to the intelligence transmitted by said space station and being received by the associated receiving means. 
     
     
       15. The system of claim 14 wherein both said transmitting and receiving antennas at each earth station have directional sensitivity, and each said station includes antenna control means for orienting both receiving and transmitting antennas to have their maximum sensitivity generally in the line-of-sight direction with respect to said space station. 
     
     
       16. The combination of claim 15 wherein said antenna control means for each said station includes means responsive to said receiving means for orienting said receiving and transmitting antennas at the respective station toward the direction from which the receiving antenna receives the maximum energization from the signal transmitted from said space station. 
     
     
       17. The method of communicating signal intelligence between two widely spaced stations on earth via a body in space, comprising the steps of transmitting from one of said stations simultaneously different carrier frequency waves each modulated according to the intelligence to be transmitted, receiving at said body in space the several carrier waves impinging thereon, demodulating at said body in space the strongest of the several received carrier waves to thereby obtain a signal containing said intelligence, transmitting from said body in space another carrier frequency wave modulated according to said intelligence signal received from the strongest carrier, and receiving and demodulating at the other of said stations the modulated signal received from said body in space. 
     
     
       18. The method of claim 17 in which the signal from said body in space may be transmitted on any one of a plurality of different frequencies and the particular frequency selected at any instant is the one which is closest to that on which said body is then receiving the strongest signal from said one station. 
     
     
       19. The method of claim 18 in which an antenna at said other station is directed to have its maximum sensitivity along the direction from which said radio wave from said body in space is received. 
     
     
       20. Means for communicating between two bodies in space having a substantial radial velocity component therebetween resulting in a substantial frequency shift in a a received radio wave as compared to the frequency of the transmitted wave and comprising, receiving and transmitting means at both said bodies with both transmitting means transmitting normally on respectively different nominal frequencies, first means at one of said bodies producing a first signal having a value representative of the frequency transmitted from the other of said bodies, means at said one body coupled to said receiving means responsive to said first signal for producing an output having at least one characteristic thereof which is proportional to the Doppler difference in frequency between the signal received at said one body from the other said body and the signal transmitted from said other body, second means at said one body producing a second signal having a value representative of the pass-band of frequencies of the receiving means for the other of said bodies, frequency-control means at said one body responsive to said output and to said second signal for controlling the frequency of the signal transmitted by said transmitting means from said one body to differ from its said nominal frequency by an amount substantially proportional to the amount of said Doppler frequency difference, said frequency control means shifting the frequency transmitted from said one body in a direction opposite to the direction of the frequency shift in the signal received from the other body, said receiving means on said other body being responsive only within a pass-band that encompasses said nominal frequency of said transmitting means at said one body. 
     
     
       21. Means for communicating between two stations in space having a substantial radial velocity component therebetween such that a radio wave transmitted from one station is received with a substantial Doppler frequency shift at the other of said stations, the combination comprising: first transmitting means of one of said stations for transmitting a carrier wave on a fixed predetermined frequency, first receiving means at said one station for receiving carrier waves occurring within a predetermined pass-band, second receiving means at the other of said stations receiving the carrier frequency wave transmitted from said one station, first means at said other station generating a signal representative of said fixed predetermined frequency, control means coupled to said second receiving means and responsive to said signal and being distinctively controlled according to the frequency difference between the carrier wave received from said one station and the predetermined frequency transmitted from said one station, variable frequency transmitting means at said other station operating at a frequency range other than said fixed predetermined frequency, said control means and said second means jointly varying the frequency of the carrier wave transmitted by said variable frequency transmitting means by an amount proportional to the frequency shift of the carrier wave received from said one station to thereby cause said carrier wave transmitted by said variable frequency transmitting means to be received by said first receiving means within said pass-band. 
     
     
       22. The method of communicating the same signal intelligence from each of at least two transmitting stations on one body in space to a receiving station on a second body in space comprising the steps of: transmitting carrier waves from both of said two stations to said second body in space;   modulating each of said carrier waves with the signal intelligence to be transmitted to said receiving station on said second body in space;   measuring the difference in distance between each respective one of said transmitting stations on said first body in space to said receiving station on said second body in space;   and delaying the modulating signal intelligence to that transmitting station which is nearer said body in space relative to the same modulating signal intelligence for the other of said transmitting stations and by an amount substantially equal to the transmission time of said carrier wave in space over the distance measured in the immediately preceding step;   whereby said signal intelligence is received at said receiving station in substantial phase coincidence for both of said transmitting stations.   
     
     
       23. A system for communicting electromagnetic intelligence signals between bodies in space, said signals while being radiated between said bodies being subject to space propagation phenomena including spin fading, amplitude scintillation, frequency scintillation, polarization fading, signal reflection, signal ducting, and signal black-out, said system comprising, means on said one body including a first directive antenna means transmitting a first signal in a highly directive beam toward the other said body in space, and signal direction finding means on said one body responsive to a signal transmitted from said other body which is subject to said space propagation phenomena .Iadd.substantially .Iaddend..[.substationally.]. the same as said first signal for .Iadd.continually .Iaddend..[.continuously.]. controlling the direction of transmission of said directive antenna means in both azimuth and elevation to maximize the intensity of signal reception at said other body, said direction finding means including at least one antenna means having a single axis of directivity and means responsive to coincidence of said axis with the direction of signal reception from said other body for controlling said directivity of transmission. 
     
     
       24. The system of claim 23 in which said other body in space is a satellite repeatedly orbiting about the earth's center. 
     
     
       25. The system of claim 23 in which said signal transmitted from said other body is an intelligence signal. 
     
     
       26. The system of claim 23 in which said direction finding means includes means for repeatedly moving said direction finding means to bring its single axis of directivity into momentary coincidence with said direction of energy reception from said other body in space. 
     
     
       27. A system for receiving an electromagnetic intelligence signal from a body in space, said received intelligence signal being subject to space propagatiotn phenomena including spin fading, amplitude scintillation, frequency scintillation, polarization fading, signal ducting, and signal black-out, said system comprising means including a first directive antenna means for directionally receiving said signal from said body in space, and satellite signal direction finding means responsive to a signal from said body in space which is subject to said propagation substantially the same as said received signal for continually controlling the direction of reception of said first directive antenna means in both azimuth and elevation to maximize the intelligence signal received from said body in space, said direction finding means including at least one antenna means having a single axis of directivity and means responsive to coincidence of said axis with the direction of signal reception from said body in space for controlling said directivity of reception. 
     
     
       28. The system of claim 27 in which said body in space is a satellite repeatedly orbiting about the earth's center. 
     
     
       29. The system of claim 27 in which the signal to which said direction finding means responds is the same as said intelligence signal received by said first directive antenna means. 
     
     
       30. The system of claim 27 in which said direction finding means includes means for repeatedly moving said direction finding means to bring its single axis of directivity into momentary coincidence with said direction of energy reception from said other body in space. .Iadd. 31. A system for communicating electromagnetic intelligence signals between bodies in space, said signals while being radiated between said bodies in space being subject to space propagation phenomena including spin fading, amplitude scintillation, frequency scintillation, polarization fading, signal reflection, signal ducting, and signal black-out, said system comprising, means on said one body including a first directive antenna means transmitting a first signal in a highly directive beam toward the other said body in space,   means on said one body including a second directive antenna means for directionally receiving a second signal from said other body in space,   signal direction finding means on said one body responsive to a signal from said other body which is subject to said space propagation phenomena substantially the same as said first transmitted signal and also substantially the same as said second received signal for continually controlling the direction of transmission of said first directive antenna means in both azimuth and elevation to maximize the intensity of signal reception of said first signal at said other body and for also continually controlling the direction of reception of said second directive antenna means in both azimuth and elevation to maximize the intensity of reception of said second signal received from said other body,   said direction finding means including at least one antenna means having a single axis of directivity and means responsive to coincidence of said axis with the direction of signal reception from said other body for controlling said direction of transmission of said first directive antenna means and also the direction of reception of said second antenna means..Iaddend.