Patent ID: 8019540

Claim:
A method of determining information for determining position of a terminal based on a received modulated navigation signal of a satellite navigation system, said received modulated navigation signal containing at least four navigation codes, the received navigation signal being generated by encoding the navigation codes in a complex binary offset carrier (BOC) signal with a defined subcarrier frequency such that a resulting encoded navigation signal has a constant amplitude, and modulating the encoded navigation signal onto a carrier signal in a second modulation to generate said modulated navigation signal to be transmitted; said method comprising: a satellite of said satellite navigation system transmitting said modulated navigation signal to said terminal; said terminal receiving said transmitted modulated navigation signal and demodulating the received modulated navigation signal in order to obtain the encoded navigation signal; generating at least one reference signal (r 1 , r 2 , r 3 , r 4 ) by multiplication of one of the at least four navigation codes by a subcarrier signal, said at least one reference signal (r 1 , r 2 , r 3 , r 4 ) being represented by r 1 = e 1 · C · [ · sign ⁡ ( cos ⁡ ( 2 ⁢ π ⁢ ⁢ f s ⁢ t ) ) + jsign ⁡ ( sin ⁡ ( 2 ⁢ π ⁢ ⁢ f s ⁢ t ) ) + ( 1 + j ) · 2 2 · sign ⁡ ( sin ⁡ ( 2 ⁢ π ⁢ ⁢ f s ⁢ t + π / 4 ) ) + ( - 1 + j ) · 2 2 · sign ⁡ ( sin ⁡ ( 2 ⁢ π ⁢ ⁢ f s ⁢ t - π / 4 ) ) ⁢ ] ⁢ ⁢ or r 2 = e 2 · C · [ · sign ⁡ ( cos ⁡ ( 2 ⁢ π ⁢ ⁢ f s ⁢ t ) ) - jsign ⁡ ( sin ⁡ ( 2 ⁢ π ⁢ ⁢ f s ⁢ t ) ) + ( 1 - j ) · 2 2 · sign ⁡ ( sin ⁡ ( 2 ⁢ π ⁢ ⁢ f s ⁢ t + π / 4 ) ) + ( - 1 - j ) · 2 2 · sign ⁡ ( sin ⁡ ( 2 ⁢ π ⁢ ⁢ f s ⁢ t - π / 4 ) ) ] ⁢ ⁢ or ⁢ r 3 = e 3 · C · [ · j · sign ⁡ ( cos ⁡ ( 2 ⁢ π ⁢ ⁢ f s ⁢ t ) ) + jsign ⁡ ( sin ⁡ ( 2 ⁢ π ⁢ ⁢ f s ⁢ t ) ) + ( - 1 + j ) · 2 2 · sign ⁡ ( sin ⁡ ( 2 ⁢ π ⁢ ⁢ f s ⁢ t + π / 4 ) ) + ( - 1 - j ) · 2 2 · sign ⁡ ( sin ⁡ ( 2 ⁢ π ⁢ ⁢ f s ⁢ t - π / 4 ) ) ] ⁢ ⁢ or r 4 = e 4 · C · [ · j · sign ⁡ ( cos ⁡ ( 2 ⁢ π ⁢ ⁢ f s ⁢ t ) ) - jsign ⁡ ( sin ⁡ ( 2 ⁢ π ⁢ ⁢ f s ⁢ t ) ) + ( 1 + j ) · 2 2 · sign ⁡ ( sin ⁡ ( 2 ⁢ π ⁢ ⁢ f s ⁢ t + π / 4 ) ) + ( 1 - j ) · 2 2 · sign ⁡ ( sin ⁡ ( 2 ⁢ π ⁢ ⁢ f s ⁢ t - π / 4 ) ) ] wherein e 1 , e 2 , e 3 , e 4 correspond to one of the at least four navigation codes, f s corresponds to a subcarrier frequency of the BOC signal and C is a constant; performing a complex correlation of the encoded navigation signal and said at least one reference signal; determining a time offset between the navigation code in the encoded navigation signal and said at least one reference signal as a result of said complex correlation; and using the thus determined time offset as a basis for position determination of said terminal.