Moving platform roll angle determination system using RF communications link

Patent metadata

Field	Value
Publication number	US-10892832-B2
Application number	US-201414538623-A
Country	US
Kind code	B2
Filing date	Nov 11, 2014
Priority date	Nov 11, 2014
Publication date	Jan 12, 2021
Grant date	Jan 12, 2021

Abstract

An orientation tracking system for a moving platform includes a transmitter which generates an beam having a known polarization with respect to a predefined coordinate system. The moving platform includes an ellipsometric detector capable of detecting the polarized beam when within the line-of-sight of the transmitter, and measuring its polarization state. The polarization state indicates the rotational orientation of the moving platform with respect to the predefined coordinate system. The beam could also be used to convey guidance commands to the platform.

First claim

We claim:

1. A moving platform orientation measurement system, comprising:
a ground-based transmitter, comprising a dual-polarized transmitting antenna, said ground-based transmitter arranged to:
generate two distinct, orthogonal linearly polarized radio frequency (RF) signals,
receive said two distinct, orthogonal linearly polarized RF signals at said dual-polarized transmitting antenna; and to
simultaneously radiate said two distinct, orthogonal linearly polarized radio frequency (RF) signals from said dual-polarized transmitting antenna,
said transmitted RF signals having known but different polarizations with respect to a predefined coordinate system; and

at least one moving platform, each moving platform comprising a linearly polarized receiving antenna capable of receiving said two orthogonal linearly polarized RF signals, said transmitter and receiving antenna arranged such that the roll angle of said moving platform can be determined based on the ratio of the power amplitudes of said two orthogonal linearly polarized RF signals, said roll angle θ given by tan −1 (P v /P h ) where P v is the power amplitude of said received RF signal in the vertical direction and P h is the power amplitude of said received RF signal in the horizontal direction;
wherein said ground-based transmitter is arranged to encode guidance commands into said two distinct, orthogonal linearly polarized RF signals by modulating at least one of said transmitted RF signals and said moving platform is arranged to detect and decode said signals and thereby detect said guidance commands.

2. The system of claim 1 , wherein each of said at least one RF signal has an associated frequency in the range of 30-300 GHz.

3. The system of claim 2 , wherein each of said at least one RF signal has an associated frequency in the range of 100-250 GHz.

4. The system of claim 1 , further comprising a diplexer coupled to the output of said receiving antenna and arranged to output first and second signals that vary with the amplitudes of said received orthogonal linearly polarized RF signals.

5. The system of claim 1 , wherein said transmitting and receiving antennas have associated bandwidths, said transmitter arranged such that said two orthogonal linearly polarized RF signals have respective frequencies which are unequal but within the bandwidths of both said transmitting and receiving antennas.

6. The system of claim 1 , wherein said transmitter is arranged to encode information into said RF signals by modulating one or both of said transmitted RF signals.

7. The system of claim 6 , wherein said modulation is amplitude modulation, frequency modulation, or phase modulation.

8. The system of claim 1 , wherein said transmitter is arranged to encode guidance commands into said RF signals by modulating the power amplitudes of one or both of said transmitted orthogonal linearly polarized RF signals, and said receiving antenna on said moving platform is arranged to receive said guidance commands by determining the sum of the power amplitudes of said received orthogonal linearly polarized RF signals.

9. The system of claim 1 , wherein said receiving antenna on the moving platform receives said orthogonal linearly polarized RF signals and produces first and second output signals which represent the power amplitudes of said received orthogonal linearly polarized RF signals at first and second orthogonal linear polarizations, respectively, said roll angle determined based on the ratio of the power amplitudes of said first and second output signals.

10. The system of claim 9 , wherein said receiving antenna is a patch antenna.

11. The system of claim 10 , wherein said patch antenna is a dual-frequency antenna.

12. The system of claim 9 , wherein said transmitter is arranged to encode information into said RF signals by modulating said transmitted orthogonal linearly polarized RF signals.

13. The system of claim 12 , wherein said modulation is amplitude modulation, frequency modulation, or phase modulation.

14. The system of claim 9 , wherein said transmitter is arranged to encode guidance commands into said RF signals by modulating said orthogonal transmitted linearly polarized RF signals.

15. The system of claim 14 , wherein said transmitter is arranged to encode guidance commands into said RF signals by modulating the power amplitude of said transmitted orthogonal linearly polarized RF signals, and said receiving antenna on said moving platform is arranged to receive said guidance commands by determining the sum of the power amplitudes of said first and second output signals.

16. The system of claim 1 , wherein said transmitter is arranged to generate RF signals such that the roll angle of multiple moving platforms can be determined.

17. The system of claim 1 , wherein each of said at least one moving platform is a steerable bullet.

18. The system of claim 1 , wherein said moving platform is arranged to receive guidance commands via said received RF signals and to vary its trajectory in response to said guidance commands.

19. The system of claim 18 , wherein said moving platform includes a control device which affects the path of said platform when actuated and which rotates with said platform, said transmitter arranged to send guidance commands which actuate said control device such that said platform's trajectory is affected, said system arranged to detect how said platform's trajectory is affected by said actuation and to thereby determine the position of said control device at the time of said actuation.

20. The system of claim 1 , wherein said moving platform has an associated longitudinal axis around which it rotates, said receiving antenna arranged to be rotationally symmetric around said longitudinal axis.

21. The system of claim 1 , wherein said moving platform has an associated longitudinal axis around which it rotates and said receiving antenna has a directional reception pattern, said receiving antenna arranged such that said directional reception pattern is pointed off-axis with respect to said longitudinal axis.

22. The system of claim 21 , wherein said receiving antenna is a dual-polarized antenna, a dual-frequency antenna, or both, with the directional reception pattern for both polarizations and/or frequencies being pointed off-axis.

23. The system of claim 21 , further comprising a means of monitoring the power modulation in the output of said receiving antenna at the frequency of rotation.

24. The system of claim 1 , wherein said receiving antenna is coupled to a receiver.

25. The system of claim 24 , wherein said transmitter and receiver have a heterodyne-based architecture.

26. The system of claim 1 , wherein said two orthogonal linearly polarized radio frequency (RF) signals are of equal power and contain identical data.

27. A moving platform orientation measurement system, comprising:
a transmitter which includes a transmitting antenna and is arranged to transmit at least one radio frequency (RF) signal, each transmitted RF signal having a known polarization with respect to a predefined coordinate system and, when there are more than one transmitted RF signal, said RF signals having known but different polarizations with respect to said predefined coordinate system; and
at least one moving platform, each moving platform comprising a receiving antenna capable of receiving said at least one polarized RF signal

Assignees

• Teledyne Scient & Imaging Llc

Inventors

• Young Adam
• Winker Bruce K

Classifications

• G01S5/0247

  Determining attitude · CPC title

• H04B14/008 Primary

  Polarisation modulation · CPC title