US3680118A
Expired / Lapsed
US
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Aircraft navigation receiver apparatus using active filters
Assignee: STATISTICAL SERVICES Inc
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Filing: 1970-07-14
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Granted: 1972-07-25
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Expires: 1990-07-14
Abstract
Abstract Aircraft navigation receiver apparatus of the kind in which two data signals are compared to determine the orientation of an aircraft (e.g., VOR and ILS receivers). Active filters, including integrators, constant current amplifiers and differential tuned amplifiers, and particularly constant slew rate filters, eliminate extraneous frequencies from the data signals without the phase distortion and other errors of passive filter circuits. A limiter circuit is preferably interposed in the receiver apparatus ahead of any of the filtering means. A phase detector that is inherently immune to amplitude variations is provided. For VOR receivers, a phase discriminator that is inherently immune to amplitude modulation distortion is presented. An AGS circuit for the receiver apparatus, which operates substantially independently of any amplitude modulation in the received signal, is provided.
Inventors
- 👤 Myron L Anthony
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 10:59
CPC Classifications
H; H03; H03H; H03H11/00; H03H11/02; H03H11/04; H03H11/12; H03H11/1217; G; G01; G01S; G01S1/00; G01S1/02
Claims Analysis
Total Claims: 27
Claim 1
Independent Claim
161 words
Aircraft navigation receiver apparatus, of the kind in which first and second data signals radiated from a navigation station are compared to determine the orientation of an aircraft relative to a reference, comprising: a first signal channel for translating said first data signal into a form suitable for comparison with the second data Signal, said first signal channel comprising active filtering means for effectively eliminating extraneous signals accompanying said first data signal without appreciable distortion of said first data signal; a second signal channel for translating said second data signal into a form suitable for comparison with the first data signal, said second signal channel comprising active filtering means for effectively eliminating extraneous signals accompanying said second data signal without appreciable distortion of said second data signal; and utilization means, comprising comparison means coupled to said first and second signal channels, for comparing said first and second data signals, as translated through said channels, to determine the orientation of the aircraft.
Claim 2
Dependent Claim
161 words
Aircraft navigation receiver apparatus, of the kind in which first and second data signals radiated from a navigation station are compared to determine the orientation of an aircraft relative to a reference, comprising: a first signal channel for translating said first data signal into a form suitable for comparison with the second data Signal, said first signal channel comprising active filtering means for effectively eliminating extraneous signals accompanying said first data signal without appreciable distortion of said first data signal; a second signal channel for translating said second data signal into a form suitable for comparison with the first data signal, said second signal channel comprising active filtering means for effectively eliminating extraneous signals accompanying said second data signal without appreciable distortion of said second data signal; and utilization means, comprising comparison means coupled to said first and second signal channels, for comparing said first and second data signals, as translated through said channels, to determine the orientation of the aircraft.
Claim 3
Dependent Claim
40 words
Aircraft navigation receiver apparatus according to claim 1 in which said active filtering means in at least one of said signal channels comprises a limiter amplifier and two integrator circuits interposed in series with each other in said signal channel.
Claim 4
Dependent Claim
50 words
Aircraft navigation receiver apparatus according to claim 2 in which each of said integrator circuits comprises a solid state operational amplifier having a resistor connected in series in the input to the amplifier and further having a capacitor connected in parallel between the input and the output of the amplifier.
Claim 5
Dependent Claim
60 words
An aircraft navigation receiver apparatus according to claim 1 in which said active filtering means in at least one of said signal channels comprises a limiter amplifier connected in series with two constant current amplifiers each having an input and an output and each having a capacitor connected from the output of the amplifier to a source of reference potential.
Claim 6
Dependent Claim
95 words
Aircraft navigation receiver apparatus according to claim 1, in which said active filtering means in at least one of said signal channels comprises a limiter amplifier for developing a data signal of rectangular waveform, a differential amplifier having one input coupled to the output of said limiter amplifier, and a variable-resonance circuit, initially tuned to the data signal frequency, coupled to the output of said differential amplifier and varied in its resonance frequency by the output signal of said differential amplifier, said variable-resonance circuit being coupled back to a second input of said differential amplifier.
Claim 7
Dependent Claim
44 words
Aircraft navigation receiver apparatus according to claim 1 in which said active filtering means in at least one of said signal channels is a constant slew rate circuit producing an output signal of constant linear slope upon application of a step function signal thereto.
Claim 8
Dependent Claim
103 words
Aircraft navigation receiver apparatus according to claim 6, in which said constant slew rate circuit comprises: an integrated solid state amplifier having an inverting input, non-inverting input, and an output; first feedback means comprising a capacitor connected to said output of said amplifier, sensing impedance connected from said capacitor to a plane of reference potential, and an A.C. rate feedback circuit connected from the common terminal of said capacitor and said sensing impedance to one input of said amplifier; and second feedback means comprising a negative feedback D.C. stabilization circuit connected from said amplifier output to one of said inputs of said amplifier.
Claim 9
Dependent Claim
75 words
Aircraft navigation receiver apparatus according to claim 1, comprising a receiver in which said first signal channel is a reference signal channel having a high-pass filter in its initial stage and further having a discriminator circuit interposed between said high-pass filter and said active filtering means, and said second signal channel is a variable signal channel having a low-pass filter in its initial stage ahead of said active filtering means for said second signal channel.
Claim 10
Dependent Claim
41 words
Aircraft navigation receiver apparatus according to claim 8, for use with VOR signals, in which said high-pass and low-pass filters are resistance-capacitor filtErs having operational characteristics that intersect each other approximately at the logarithmic mean of 30 hz and 9,960 hz.
Claim 11
Dependent Claim
89 words
Aircraft navigation receiver apparatus according to claim 8 in which said discriminator comprises a push-pull differential amplifier having two inputs to which said data signal is supplied in opposite phase, the two stages of said amplifier each being driven to saturation in alternate half cycles of said first data signal, and in which said data signal is applied, with a phase shift of 90*, to a common connection for both stages of said push-pull differential amplifier, to cut off both stages of said differential amplifier in alternate half cycles.
Claim 12
Dependent Claim
69 words
Aircraft navigation receiver apparatus according to claim 10, in which the circuit for supplying said data signal with 90* phase shift to both stages of said push-pull differential amplifier comprises, in series, a follower amplifier, an inductance-capacitance tuned circuit driven in series and having an output taken from a parallel connection, and an additional follower amplifier for coupling the output of said tuned circuit to said differential push-pull amplifier.
Claim 13
Dependent Claim
29 words
Aircraft navigation receiver apparatus according to claim 8 in which said high-pass filter is a constant current differentiator circuit and said low-pass filter is a constant current integrator circuit.
Claim 14
Dependent Claim
58 words
Aircraft navigation receiver apparatus according to claim 10 in which said active filtering means in at least one of said signal channels comprises a limiter amplifier in series with two constant current amplifiers each having an input and an output and each having a capacitor connected from the output of the amplifier to a source of reference potential.
Claim 15
Dependent Claim
49 words
An aircraft navigation receiver apparatus according to claim 12 in which a limiter circuit is incorporated in the receiver apparatus before any filtering means in either of said first and second signal channels, whereby the first and second data signals supplied to said channels are of substantially rectangular waveform.
Claim 16
Dependent Claim
94 words
Aircraft navigation receiver apparatus according to claim 8 in which said comparison means comprises a push-pull differential amplifier, having two individual inputs with means for applying the first data signal from said first channel to said two inputs in phase opposition, each stage of said amplifier being driven to saturation in alternate half cycles, and a third input common to both stages of said push-pull differential amplifier with means for applying the second data signal from said second channel to said third input to drive both stages to cut off in alternate half cycles.
Claim 17
Dependent Claim
93 words
Aircraft navigation receiver apparatus according to claim 8 and further including phase adjusting means for adjusting the phase of one of said data signals as applied to said push-pull amplifier, said phase adjusting means comprising a resolver having two stationary quadrature windings to which said one data signal is applied and having a rotatable output winding disposed within the magnetic field of said stationary windings, and means for adjusting the angular position of said output winding to vary the relative phase of said one data signal as applied to said push-pull differential amplifier.
Claim 18
Dependent Claim
131 words
Aircraft navigation receiver apparatus according to claim 8 in which said high-pass filter is an amplifier having a constant slew rate circuit connected in a negative feedback circuit for the amplifier, said constant slew rate circuit comprising: a main integrated solid state amplifier having an inverting input, a non-inverting input, and an output; first feedback means comprising a capacitor connected to said output of said main amplifier, a sensing impedance connected from said capacitor to a plane of reference potential, and an A.C. rate feedback circuit connected from the common terminal of said capacitor and said sensing impedance to one input of said main amplifier; and second feedback means comprising a negative feedback D.C. stabilization circuit connected from said main amplifier output to one of said inputs of said main amplifier.
Claim 19
Dependent Claim
127 words
Aircraft navigation receiver apparatus according to claim 8, in which said active filtering means in each channel, other than said high-pass and low-pass filters, includes at least one constant slew rate circuit comprising: a main integrated solid state amplifier having an inverting input, a non-inverting input, and an output; first feedback means comprising a capacitor connected to said output of said main amplifier, a sensing impedance connected from said capacitor to a plane of reference potential, and an A.C. rate feedback circuit connected from the common terminal of said capacitor and said sensing impedance to one input of said main amplifier; and second feedback means comprising a negative feedback D.C. stabilization circuit connected from said main amplifier output to one of said inputs of said main amplifier.
Claim 20
Dependent Claim
84 words
Aircraft navigation receiver apparatus according to claim 18 in which said rate feedback circuit in the CSR circuit includes threshold means precluding any effective rate-limiting A.C. feedback to said main amplifier until the voltage drop across said sensing impedance exceeds a predetermined minimum threshold voltage, said threshold means including a pair of diodes connected in parallel with each other and in opposed polarities, interposed in said rate feedback circuit, and in which said minimum threshold voltage is the forward breakdown voltage of said diodes.
Claim 21
Dependent Claim
90 words
Aircraft navigation receiver apparatus according to claim 1 and further comprising an automatic gain control circuit in the input to stages of said receiver apparatus ahead of said first and second signal channels, said AGC circuit comprising an amplifier operating at constant gain, a plurality of series-connected purely reactive voltage dividers connected in the input to said amplifier, and a direct-current feedback circuit from the output of said amplifier to each of said voltage divider circuits for varying the reactance of one leg in each of said voltage divider circuits.
Claim 22
Dependent Claim
28 words
Aircraft navigation receiver apparatus according to claim 20 in which said one leg of each of said voltage dividers that varies in reactance comprises a voltage-responsive variable capacitor.
Claim 23
Dependent Claim
147 words
Aircraft navigation receiver apparatus, of the kind in which first and second data signals of corresponding frequency but varying phase are compared to determine the orientation of an aircraft relative to a reference path, comprising: first and second signal channels for segregating said data signals from each other and for effectively eliminating extraneous signals therefrom; and comparison means for comparing said data signals, said comparison means comprising a push-pull differential amplifier, having two individual inputs with means for applying the first data signal from said first channel to said two inputs in phase opposition, each stage of said amplifier being driven to saturation in alternate half cycles, and a third input common to both stages of said push-pull differential amplifier with means for applying the second data signal from said second channel to said third input to drive both stages to cut off in alternate half cycles.
Claim 24
Dependent Claim
147 words
Aircraft navigation receiver apparatus, of the kind in which first and second data signals of corresponding frequency but varying phase are compared to determine the orientation of an aircraft relative to a reference path, comprising: first and second signal channels for segregating said data signals from each other and for effectively eliminating extraneous signals therefrom; and comparison means for comparing said data signals, said comparison means comprising a push-pull differential amplifier, having two individual inputs with means for applying the first data signal from said first channel to said two inputs in phase opposition, each stage of said amplifier being driven to saturation in alternate half cycles, and a third input common to both stages of said push-pull differential amplifier with means for applying the second data signal from said second channel to said third input to drive both stages to cut off in alternate half cycles.
Claim 25
Dependent Claim
83 words
Aircraft navigation receiver apparatus, according to claim 22, and further comprising an automatic gain control circuit, ahead of said first and second signal channels, said automatic gain control circuit comprising an amplifier operating at constant gain, a plurality of series-connected purely reactive voltage dividers connected in the input to said amplifier, and a direct-current feedback circuit from the output of said amplifier to each of said voltage divider circuits for varying the reactance of one leg in each of said voltage divider circuits.
Claim 26
Dependent Claim
30 words
Aircraft navigation receiver apparatus according to claim 22, and further including phase adjusting means for adjusting the phase of one of saId data signals as applied to said push-pull amplifier.
Claim 27
Dependent Claim
73 words
Aircraft navigation receiver apparatus according to claim 24 in which said phase adjusting means comprises a resolver having two stationary quadrature windings to which said one data signal is applied and having a rotatable output winding disposed within the magnetic field of said stationary windings, and means for adjusting the angular position of said output winding to vary the relative phase of said one data signal as applied to said push-pull differential amplifier.
References Cited (Backward Citations)
US3096480A
Cited
US3495247A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-07-25 | 1976-01-24 | 1976-07-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-07-25 | 1980-01-24 | 1980-07-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-07-25 | 1984-01-24 | 1984-07-25 | $7700.00 | Window Closed / Lapsed |