Diversity polarization modulation
地域：
FL
FL Melbourne
摘要
A method includes transmitting a digital code from a transmitter to a receiver. Information is transmitted via electromagnetic waves from the transmitter to the receiver. The transmission of the information includes transmitting a first portion of the information using electromagnetic waves with a first polarization in response to a first value of the digital code, and transmitting a second portion of the information using electromagnetic waves of a second polarization in response to a second value of the digital code. The first information may include a first navigational code and the second information may include a second navigational code.
說明書
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
The present disclosure relates to the transmission of signals using polarization, and in particular, the transmission of navigation codes using polarization diversity.
Global Navigation Satellite Systems (“GNSS”), Global Positioning System (“GPS”), Galileo systems and Position, Navigation and Timing (“PNT”) systems broadcast RF energy modulated with navigation information from spacecraft, airborne and terrestrial platforms. Such systems are susceptible to degradation due to multipath interference and intentional or unintentional interference from jammers or other sources. These systems are also susceptible to “spoofing,” i.e., unauthorized transmitters which send falsified GNSS-like signals with the intent to give the user erroneous position, navigation, or timing estimates. GNSS systems present challenges in designing systems that are robust and resilient to multipath, jamming, and spoofing, while minimizing the size, weight, and power required for the GNSS payload.
Related art anti jamming techniques assume that the navigation signals will be right hand circularly polarized, while the jammer signals are assumed to be linearly polarized. Other anti jamming techniques assume that the jammer signal is radiated from below the navigation system antenna horizon, but this also not always true. Accordingly, new anti jamming techniques need to be developed.
權(quán)利要求
What is claimed is:1. A method comprising:transmitting a digital code that comprises a pseudo-random code from a transmitter to a receiver; transmitting information including a first navigational code and a second navigational code via electromagnetic waves from the transmitter to the receiver, wherein transmitting the information comprises:transmitting the first navigational code using electromagnetic waves with a first polarization in response to a first value of the digital code; and transmitting the second navigational code using electromagnetic waves of a second polarization in response to a second value of the digital code, wherein the transmitting the first navigational code and the transmitting the second navigational code result in polarization hopping of the first polarization and the second polarization between different types of polarization over time according to a random pattern of the pseudo-random code. 2. The method of claim 1 , wherein the first navigational code and the second navigational code are transmitted consecutively in time. 3. The method of claim 1 , wherein:the first polarization comprises one of right hand circular polarization, left hand circular polarization, right hand elliptical polarization, left hand elliptical polarization, and/or linear polarization; and the second polarization comprises another of right hand circular polarization, left hand circular polarization, right hand elliptical polarization, left hand elliptical polarization, and/or linear polarization. 4. The method of claim 1 , wherein transmitting the digital code from the transmitter to the receiver comprises transmitting the digital code encrypted with an encryption key known to the receiver. 5. The method of claim 1 , wherein transmitting the information comprises transmitting the information using a crossed dipole antenna. 6. The method of claim 1 , wherein transmitting the first navigational code comprises transmitting the first navigational code with a first helical antenna providing right hand circular polarized electromagnetic waves; andwherein transmitting the second navigational code comprises transmitting the second navigational code with a second helical antenna providing left hand circular polarized electromagnetic waves. 7. The method of claim 1 , wherein transmitting the first navigational code and transmitting the second navigational code comprises transmitting the first navigational code and the second navigational code at the same time as a combined linearly polarized signal. 8. A method comprising:receiving, at a receiver from a transmitter, a digital code comprising a pseudo-random code; receiving, at the receiver, first electromagnetic waves; decoding, using correlation, a first navigational code from the first electromagnetic waves corresponding to a first polarization in response to a first value of the digital code, wherein the first polarization includes polarization hopping between different types of the first polarization over time according to a random pattern of the pseudo-random code, and the decoding includes determining the different types of the first polarization using the pseudo-random code; receiving, at the receiver, second electromagnetic waves; and decoding, using correlation, a second navigational code from the second electromagnetic waves corresponding to a second polarization in response to a second value of the digital code, wherein the second polarization includes polarization hopping between different types of second polarization over time according to the random pattern of the pseudo-random code, and the decoding the second navigational code includes determining the different types of second polarization using the pseudo-random code. 9. The method of claim 8 , wherein the first polarization comprises one of right hand circular polarization, left hand circular polarization, right hand elliptical polarization, left hand elliptical polarization, and/or linear polarization; andthe second polarization comprises another of right hand circular polarization, left hand circular polarization, right hand elliptical polarization, left hand elliptical polarization, and/or linear polarization. 10. The method of claim 8 , wherein receiving the digital code comprises receiving an encrypted code; andfurther comprising decrypting the encrypted code with an encryption key stored at the receiver. 11. The method of claim 8 , wherein the first polarization comprises right hand circular polarization; andwherein the second polarization comprises left hand circular polarization. 12. The method of claim 11 , further comprising determining a total power measurement of the first electromagnetic waves combined with the second electromagnetic waves; anddetermining that a jammer signal is included in at least one of the first electromagnetic waves and/or the second electromagnetic waves in response to the total power measurement exceeding a predetermined threshold. 13. The method of claim 12 , further comprising:making a power measurement of a right hand circular polarized portion of the first and second electromagnetic waves; making a power measurement of a left hand circular polarized portion of the first and second electromagnetic waves; comparing the power measurement of the right hand circular polarized portion and the power measurement of the left hand circular polarized portion; and determining a polarization of the jammer signal in response to the comparing of the power measurement of the right hand circular polarized portion and the power measurement of the left hand circular polarized portion. 14. The method of claim 13 , further comprising providing anti jamming processing in response to determining the polarization of the jamming signal. 15. A method comprisingencoding a first signal of a first channel of a transmitter with a first navigational code; encoding a second signal of the first channel of the transmitter with a second navigational code; encoding a first signal of a second channel of the transmitter with the first navigational code; encoding a second signal of the second channel of the transmitter with the second navigational code; phase shifting the first signal of the first channel by 90 degrees relative to the first signal of the second channel; phase shifting the second signal of the second channel by 90 degrees relative to the second signal of the first channel; combining the first signal of the first channel with the second signal of the first channel to generate a first channel combined signal; combining the first signal of the second channel with the second signal of the second channel to generate a second channel combined signal; and transmitting the first channel combined signal and the second channel combined signal such that the first signal is transmitted with right hand elliptical polarization and the second signal is transmitted with left hand elliptical polarization. 16. The method of claim 15 , wherein transmitting the first channel combined signal and the second channel combined signal comprises transmitting the first signal with right hand circular polarization and the second signal with left hand circular polarization. 17. The method of claim 16 , wherein transmitting the first channel combined signal comprises transmitting the first channel combined signal via a first radiating element of a crossed dipole antenna; andwherein transmitting the second channel combined signal comprises transmitting the second channel combined signal via a second radiating element of the crossed dipole antenna. 18. The method of claim 15 , wherein the first channel combined signal and the second channel combined signal are configured to be decoded at a receiver using correlation.
意見反饋
使用該功能遇到問題