Radio navigation system

Claim 2

In a radio navigation receiver for a modulated carrier signal corresponding to a received modulated radio signal transmitted from a reference station; the improvement comprising: means for generating a local modulation signal independently of the reference station and for varying the phase thereof; means for correlating the phase of the local modulation signal with the phase of the modulation of the carrier signal and for activating said generating means in accordance with the residual power of said carrier signal to vary the phase of said local modulatIon signal in a direction to correlate with that of the carrier signal, and means for deriving a measurement signal in accordance with the amount of variation of said modulation phase as a representation of the transmission time of the radio signal.

Claim 3

The improvement in a radio navigation receiver as recited in claim 1, wherein: said measurement signal deriving means includes digital means for storing the measurement signal when the radio signal is not received.

Claim 4

The improvement in a radio navigation receiver as recited in claim 1, wherein digital storing means is operative for storing said measurement signal when the local modulation signal is correlated with the received signal.

Claim 5

A radio ranging receiver for a modulated carrier signal corresponding to a received modulated radio signal transmitted from a reference station; said receiver comprising: a plurality of signal channels, means for supplying to said channels signals including the received modulated carrier signal and a local generated modulation signal supplied to said channels in a certain phase difference relation, and separate means in each channel for combining said received and local modulation signals; means for relating the combined signals in said channels and for generating a control signal in accordance with the relation of the combined signals in said channels; and means responsive to said control signal for modifying the phases of the local modulation signals supplied to said channels and for developing a signal proportional to the amount of phase modification, said means for modifying the local signal phases tending to reduce the difference in phase between the received modulation and the local modulation in one of said channels; whereby said phase modification signal is proportional to the transmission time of the radio signal.

Claim 6

A radio ranging receiver for a modulated carrier signal corresponding to a received modulated radio signal transmitted from a reference station; said receiver comprising: a plurality of signal channels, means for supplying to said channels signals including the received modulated carrier signal and a local generated modulation signal supplied to said channels in a certain phase difference relation, and separate means in each channel for combining said received and local modulation signals; means for relating the combined signals in said channels and for generating a control signal in accordance with the relation of the combined signals in said channels; and means responsive to said control signal for modifying the phases of the local modulation signals supplied to said channels and for developing a signal proportional to the amount of phase modification, said means for modifying the local signal phases tending to reduce the difference in phase between the received modulation and the local modulation in one of said channels; whereby said phase modification signal is proportional to the transmission time of the radio signal.

Claim 7

A radio ranging receiver as recited in claim 4 wherein said means for relating the combined signals and for generating a control signal includes means for detecting the residual carrier power of said combined signals.

Claim 8

A radio ranging receiver as recited in claim 5 wherein said means for modifying the signal phases includes means responsive to the existence of substantial residual carrier power in one or the other of said channels for enabling the modifying of the phases of the local signals.

Claim 9

A radio ranging receiver as recited in claim 4 wherein each of said combining means includes means for correlating the received and local modulation signals and for producing a modulated carrier signal representative of the correlation; and said means for relating the combined signals and for generating a control signal includes means for correlating the modulated carrier signals in said channels.

Claim 10

A radio ranging receiver as recited in claim 7 wherein the local modulation in one of said channels is in quadrature with respect to the other.

Claim 11

A radio ranging receiver as recited in claim 8 wherein the received and local modulations are rectangular waves having portions of positive and negative polarities.

Claim 12

A radio ranging receiver as recited in claim 4 wherein said means for modifying the signal phases includes means responsive to the existence of combined signals in one or the other of said channels for enabling the modifying of the phases of the local signals.

Claim 13

A radio ranging receiver as recited in claim 10 wherein said means for enabling the phase modifying of the local signals includes means for detecting the existence of residual carrier power above a certain level.

Claim 14

A radio ranging receiver as recited in claim 11 wherein said phase modifying means includes means for adjusting the local modulation phase in discrete steps.

Claim 15

In a radio navigation receiver as recited in claim 1 wherein said generating means includes means for varying said signal phase in discrete steps and for maintaining the phase between said steps of variation; and said means for activating said generating is Responsive to a substantial level of carrier signal power.

Claim 18

A measuring system as recited in claim 14, wherein said controlling of the clock signal phase is in response to a substantial level of residual carrier power.

Claim 19

A measuring system as recited in claim 15, wherein the controlling of the phase of the clock is by adjustment of discrete steps thereof and by maintaining the phase between adjustments, and wherein the process of said system is repeated until the clock signal is in said certain phase relation with the received modulation.

Claim 20

A measuring system as recited in claim 15, wherein said combining of the clock signal with the carrier modulation is separately performed with two phase displaced forms of the clock signal to produce two combined modulated carrier signals; and said carrier power detecting includes the correlating of the combined modulated carrier signals.

Claim 21

A measuring system as recited in claim 17, wherein said controlling of the clock signal phase is in response to a substantial level of residual carrier power in one or the other of said combined modulated carrier signals.

Claim 22

A measuring system as recited in claim 14, and further comprising transmitting said modulated carrier including generating the modulation for said carrier independently of said local clock.

Claim 23

A radio ranging receiver as recited in claim 4, in combination with a radio transmitter, said transmitter comprising: means for transmitting said modulated radio signal including means for generating the modulation for said radio signal independently of the local generated modulation signal of said receiver.

Claim 24

The improvement in a radio navigation receiver as recited in claim 1, in combination with a radio transmitter, said transmitter comprising: means for transmitting said modulated radio signal including means for generating the modulation for said radio signal independently of the local generated modulation signal of said receiver.