Radio guidance system with separate transmission of a standard frequency signal to enhance the discrimination of the receiver

Claim 2

An improved guidance system comprising apparatus for a craft to be guided including a receiver operable to receive guidance signals within a predetermined band of radio frequencies from ground stations, said receiver including means for receiving a separate fixed standard frequency signal from a ground station and operable to control said receiver to enhance the discrimination function of said receiver in discriminating the desired guidance signals within said predetermined band of frequencies from other signals, said receiver being operable to receive guidance signals within two predetermined bands of frequencies from ground stations, and said separate fixed standard frequency signal being within one of said predetermined bands of frequencies.

Claim 3

An improved guidance system comprising apparatus for a craft to be guided including a receiver operable to receive guidance signals within a predetermined band of radio frequencies from ground stations, said receiver including means for receiving a separate fixed standard frequency signal from a ground station and operable to control said receiver to enhance the discrimination function of said receiver in discriminating the desired guidance signals within said predetermined band of frequencies from other signals, said receiver being operable to receive guidance signals within two predetermined bands of frequencies from ground stations, and said separate fixed standard frequency signal being within one of said predetermined bands of frequencies.

Claim 4

An improved guidance system comprising apparatus for a craft to be guided including a receiver operable to receive guidance signals within a predetermined band of radio frequencies from ground stations, said receiver including means for receiving a separate fixed standard frequency signal from a ground station and operable to control said receiver to enhance the discrimination function of said receiver in discriminating the desired guidance signals within said predetermined band of frequencies from other signals, said receiver being operable to receive guidance signals within two predetermined bands of frequencies from ground stations, and said separate fixed standard frequency signal being within one of said predetermined bands of frequencies.

Claim 5

A system as claimed in claim 1 wherein one of said predetermined bands of frequencies is in the C band, and the other of said predetermined bands of frequencies is in the Ku band.

Claim 6

A system as claimed in claim 2 wherein said separate fixed standard frequency signal is within the C band.

Claim 7

A system as claimed in claim 2 wherein said separate fixed standard frequency is within the Ku band.

Claim 8

A system as claimed in claim 3 wherein said means for receiving said separate fixed standard frequency signal to enhance discrimination comprises a local oscillator having a controllable oscillation frequency which is stabilized by a signal deRived from the fixed standard frequency signal, the fundamental oscillator frequency being employed to discriminate C band signals, and the third harmonic frequency of said oscillator being used to discriminate said Ku band signals.

Claim 9

An improved guidance system comprising apparatus for a craft to be guided including a receiver operable to receive guidance signals within a predetermined band of radio frequencies from ground stations, said receiver including means for receiving a separate fixed standard frequency signal from a ground station and operable to control said receiver to enhance the discrimination function of said receiver in discriminating the desired guidance signals within said predetermined band of frequencies from other signals, said receiver including a translator selectively operable to translate incoming signals from different predetermined sub-bands to a predetermined intermediate frequency band usable within said receiver, said sub-bands having different fixed frequency differences from said fixed standard frequency.

Claim 10

An improved guidance system comprising apparatus for a craft to be guided including a receiver operable to receive guidance signals within a predetermined band of radio frequencies from ground stations, said receiver including means for receiving a separate fixed standard frequency signal from a ground station and operable to control said receiver to enhance the discrimination function of said receiver in discriminating the desired guidance signals within said predetermined band of frequencies from other signals, said receiver including a translator selectively operable to translate incoming signals from different predetermined sub-bands to a predetermined intermediate frequency band usable within said receiver, said sub-bands having different fixed frequency differences from said fixed standard frequency.

Claim 11

A system as claimed in claim 6 wherein said receiver and said translator are arranged to receive and translate at least two different guidance signals on two different predetermined pairs of sub-bands, said translator being selectively operable to translate incoming signals from different predetermined pairs of sub-bands to a predetermined pair of intermediate frequency bands usable within said receiver, said sub-bands having different fixed frequency differences from said fixed standard frequency.

Claim 12

An improved guidance system comprising apparatus for a craft to be guided including a guidance function receiver operable to receive guidance signals in a first predetermined band of frequencies and operable in response to said guidance signals for generating a signal indicating deviations from a predetermined path, means connected to said receiver for indicating said deviation signals for course corrections, a microwave receiver operable to receive guidance signals within a predetermined band of microwave frequencies from ground stations, said microwave receiver including a frequency converter means operable by combination with at least one fixed frequency to convert microwave frequency guidance signals received thereby to signals falling within said first predetermined band of frequencies, said microwave receiver being connected to supply said converted frequency signals respectively to said guidance function receiver, said microwave receiver including means for receiving a fixed standard frequency signal from a ground station and operable to determine the fixed frequency for conversion of the microwave frequency guidance signals.

Claim 13

An improved guidance system comprising apparatus for a craft to be guided including a guidance function receiver operable to receive guidance signals in a first predetermined band of frequencies and operable in response to said guidance signals for generating a signal indicating deviations from a predetermined path, means connected to said receiver for indicating said deviation signals for course corrections, a microwave receiver operable to receive guidance signals within a predetermined band of microwave frequencies from ground stations, said microwave receiver including a frequency converter means operable by combination with at least one fixed frequency to convert microwave frequency guidance signals received thereby to signals falling within said first predetermined band of frequencies, said microwave receiver being connected to supply said converted frequency signals respectively to said guidance function receiver, said microwave receiver including means for receiving a fixed standard frequency signal from a ground station and operable to determine the fixed frequency for conversion of the microwave frequency guidance signals.

Claim 14

An improved aircraft guidance system comprising apparatus for the aircraft including a localizer receiver operable to receive guidance signals in a first predetermined band of frequencies and operable in response to said guidance signals for generating a signal indicating lateral deviations from a predetermined flight path, a glide slope receiver operable to receive guidance signals in a second predetermined band of frequencies and operable in response to said guidance signals for generating signals indicating vertical deviations from a predetermined glide slope path, means connected to said localizer receiver and to said glide slope receiver for indicating said localizer and glide slope deviation signals for course corrections, a microwave receiver operable to receive localizer and glide slope guidance signals within a predetermined band of microwave frequencies from ground stations, said microwave receiver including a frequency converter comprising means operable by combination with at least one fixed frequency to convert microwave frequency guidance signals received thereby to signals falling within the range between the lowest and the highest frequencies included within said first and second predeTermined bands of frequencies, said microwave receiver being connected to supply said converted frequency signals respectively to said localizer receiver and to said glide slope receiver, said microwave receiver including means for receiving a fixed standard frequency signal from a ground station and operable to determine the fixed frequency for conversion of the microwave frequency guidance signals.

Claim 15

An improved aircraft guidance system comprising apparatus for the aircraft including a localizer receiver operable to receive guidance signals in a first predetermined band of frequencies and operable in response to said guidance signals for generating a signal indicating lateral deviations from a predetermined flight path, a glide slope receiver operable to receive guidance signals in a second predetermined band of frequencies and operable in response to said guidance signals for generating signals indicating vertical deviations from a predetermined glide slope path, means connected to said localizer receiver and to said glide slope receiver for indicating said localizer and glide slope deviation signals for course corrections, a microwave receiver operable to receive localizer and glide slope guidance signals within a predetermined band of microwave frequencies from ground stations, said microwave receiver including a frequency converter comprising means operable by combination with at least one fixed frequency to convert microwave frequency guidance signals received thereby to signals falling within the range between the lowest and the highest frequencies included within said first and second predeTermined bands of frequencies, said microwave receiver being connected to supply said converted frequency signals respectively to said localizer receiver and to said glide slope receiver, said microwave receiver including means for receiving a fixed standard frequency signal from a ground station and operable to determine the fixed frequency for conversion of the microwave frequency guidance signals.

Claim 16

A system as claimed in claim 8 wherein said frequency converter means includes a frequency converter operable to convert microwave frequency signals received by said microwave receiver by subtraction of a fixed frequency, and said frequency converter means also includes a frequency translator connected from said converter to said localizer and glide slope receivers, said frequency translator being operable upon the signals converted by said frequency converter to translate different complementary sub-band portions of said converted predetermined band of microwave frequencies to said first and second predetermined bands of frequencies respectively for said localizer and glide slope receivers.

Claim 17

An improved system as claimed in claim 9 wherein there is included apparatus for a ground station having at least one microwave transmitter for transmitting localizer and glide slope guidance signals, said transmitter being operable to transmit a standard frequency signal having a fixed frequency relationship to the carrier frequencies of the guidance signals.

Claim 18

A system as claimed in claim 9 wherein said frequency converter comprises a single first mixer for receiving said microwave frequency guidance signals and for also receiving said fixed standard frequency signal, a frequency adjustable oscillator connected to supply a frequency signal to said first mixer for subtraction from said microwave frequency guidance signals and said fixed standard frequency signal to thereby accomplish said conversion of said guidance signals and to convert said standard frequency signal to provide a first standard frequency difference signal reduced in frequency by more than one order of magnitude, said microwave receiver including a second mixer and oscillator combination arranged to receive the first standard frequency difference signal from said first mixer and operable by a second subtraction to derive a second standard frequency difference signal which is reduced by another order of magnitude, a discriminator and average filter operable to detect deviations of said second standard frequency difference signal from an exact frequency value corresponding to the maintenance of the converted microwave frequency guidance signals at exact frequencies within said first and second predetermined bands of frequencies and operable to issue correction signals in response to any such deviations, and a connection from said discriminator and average filter to said frequency adjustable oscillator to automatically adjust the frequency output of said adjustable oscillator to maintain said exact frequency value.

Claim 19

A system as claimed in claim 12 wherein the maximum range of frequency variation by said frequency adjustable oscillator is within the maximum frequency range of discrimination by said discriminator and average filter.

Claim 22

An improved guidance system comprising at least one ground station transmitter for transmitting radio guidance signals within a predetermined band of radio frequencies to a craft to be guided, said transmitter including means for transmitting a separate fixed standard frequency signal for use by the receiver to enhance the discrimination function of the receiver in discriminating the desired guidance signals within said predetermined band of frequencies from other signals, said transmitter being operable to transmit guidance signals within two predetermined bands of frequencies, and said separate fixed standard frequency signal being within one of said predetermined bands of frequencies.

Claim 23

An improved guidance system comprising at least one ground station transmitter for transmitting radio guidance signals within a predetermined band of radio frequencies to a craft to be guided, said transmitter including means for transmitting a separate fixed standard frequency signal for use by the receiver to enhance the discrimination function of the receiver in discriminating the desired guidance signals within said predetermined band of frequencies from other signals, said transmitter being operable to transmit guidance signals within two predetermined bands of frequencies, and said separate fixed standard frequency signal being within one of said predetermined bands of frequencies.

Claim 24

A system as claimed in claim 15 wherein one of said predetermined bands of frequencies is in the C band, and the other of said predetermined bands of frequencies is in the Ku band.

Claim 25

A system as claimed in claim 16 wherein said separate fixed standard frequency signal is within the C band.

Claim 26

A system as claimed in claim 16 wherein said separate fixed standard frequency is within the Ku band.

Claim 27

An improved guidance system comprising apparatus for a craft to be guided including a guidance function receiver operable to receive guidance signals in a first predetermined band of frequencies and operable in response to said guidance signals for generating a signal indicating deviations from a predetermined path, means connected to said receiver for indicating said deviation signals for course corrections, a radio frequency receiver operable to receive guidance signals within a predetermined band of radio frequencies from ground stations, said radio frequency receiver including a local oscillator means and a frequency converter means operable by combination with a frequency from said local oscillator means to convert the radio frequency guidance signals to signals falling within said first predetermined band of frequencies, a connection means from said radio frequency receiver to supply said converted frequency signals to said guidance function receiver, said radio frequency receiver including means for receiving a standard frequency signal from a ground station having a fixed frequency relationship to said radio frequency guidance signals and operable in response to said standard frequency signal to determine the local oscillator frequency for conversion of the radio frequency guidance signals.

Claim 28

An improved guidance system comprising apparatus for a craft to be guided including a guidance function receiver operable to receive guidance signals in a first predetermined band of frequencies and operable in response to said guidance signals for generating a signal indicating deviations from a predetermined path, means connected to said receiver for indicating said deviation signals for course corrections, a radio frequency receiver operable to receive guidance signals within a predetermined band of radio frequencies from ground stations, said radio frequency receiver including a local oscillator means and a frequency converter means operable by combination with a frequency from said local oscillator means to convert the radio frequency guidance signals to signals falling within said first predetermined band of frequencies, a connection means from said radio frequency receiver to supply said converted frequency signals to said guidance function receiver, said radio frequency receiver including means for receiving a standard frequency signal from a ground station having a fixed frequency relationship to said radio frequency guidance signals and operable in response to said standard frequency signal to determine the local oscillator frequency for conversion of the radio frequency guidance signals.

Claim 29

A system as claimed in claim 19 wherein said frequency converter means comprises a single first mixer for receiving said radio frequency guidance signals and for also receiving said standard frequency signal, said local oscillator means comprising a frequency adjustable oscillator connected to supply a frequency signal to said first mixer for subtraction from said radio frequency guidance signals and said standard frequency signal to thereby accomplish said conversion of said guidance signals and to convert said standard frequency signal to provide a standard frequency difference signal, a discriminator and average filter operable to detect deviations of said standard frequency difference signal from an exact frequency value corresponding to the Maintenance of the converted radio frequency guidance signals at frequencies having exact differences from said standard frequency signal and operable to issue correction signals in response to any such deviations, and a connection from said discriminator and average filter to provide said correction signals to said frequency adjustable oscillator to automatically adjust the frequency output of said adjustable oscillator to maintain said exact frequency value.