Abstract: A construction method for a (n,n(n?1),n?1) permutation group code based on coset partition is provided. The presented (n,n(n?1),n?1) permutation group code has an error-correcting capability of d?1 and features a strong anti-interference capability for channel interferences comprising multi-frequency interferences and signal fading. As n is a prime, for a permutation code family with a minimum distance of n?1 and a code set size of n(n?1), the invention provides a method of calculating n?1 orbit leader permutation codewords by On={?o1}?=1n-1(mod n) and enumerating residual codewords of the code set by Pn=CnOn={(l1)n-1On}={(rn)n-1On}. Besides, a generator of the code set thereof is provided. The (n,n(n?1),n?1) permutation group code of the invention is an algebraic-structured code, n?1 codewords of the orbit leader array can be obtained simply by adder and (mod n) calculator rather than multiplication of positive integers.

Abstract: A method for joint data-pilot tracking of navigation signal, including: multiplying a digital intermediate frequency signal with a local carrier to accomplish carrier removal; multiplying a signal after the carrier removal with a data baseband signal and a pilot baseband signal respectively to accomplish code removal; processing a signal after the code removal with integration-and-dump to obtain a coherent integration result of each branch; using the coherent integration results to accomplish data-bit flip detection and calculation of probability-weighting factor; acquiring a data-pilot joint carrier tuning-amount, and tuning the carrier numerically controlled oscillator by the carrier tuning-amount to realize data-pilot joint signal carrier tracking; and acquiring a data-pilot joint code tuning-amount, and tuning the code numerically controlled oscillator to realize baseband signal tracking.

Abstract: The invention discloses a method for receiving TD-AltBOC signal, which belongs to the field of global satellite navigation. The method of the invention includes steps of: converting a TD-AltBOC radio-frequency signal into an medium frequency, performing a band-pass filtering and sampling on the signal, and peeling off a sampled signal carrier by using a local carrier to obtain a sampled baseband signal; correlating on a local waveform with the sampled baseband signal chip-by-chip in a time division manner; performing a data demodulation according to correlated output signals, and obtaining a carrier phase deviation estimated value and a code phase deviation estimated value according to the correlated output signals; generating the local waveform according to the code phase deviation estimated value; generating the local carrier according to the carrier phase deviation estimated value. The invention also provides an apparatus for receiving TD-AltBOC signal.

Abstract: A construction method for a (n,n(n?1),n?1) permutation group code based on coset partition is provided. The presented (n,n(n?1),n?1) permutation group code has an error-correcting capability of d?1 and features a strong anti-interference capability for channel interferences comprising multi-frequency interferences and signal fading. As n is a prime, for a permutation code family with a minimum distance of n?1 and a code set size of n(n?1), the invention provides a method of calculating n?1 orbit leader permutation codewords by On={?o1}?=1n-1(mod n) and enumerating residual codewords of the code set by Pn=CnOn={(l1)n-1On}={(rn)n-1On}. Besides, a generator of the code set thereof is provided. The (n,n(n?1),n?1) permutation group code of the invention is an algebraic-structured code, n?1 codewords of the orbit leader array can be obtained simply by adder and (mod n) calculator rather than multiplication of positive integers.

Abstract: A method for evaluating the quality of a radio frequency signal for a satellite navigation system, the method comprising: sampling the payload radio frequency signal of a satellite to obtain an intermediate frequency signal, and filtering the signal; downconverting the filtered intermediate signal to obtain the corresponding actual baseband signal; generating the signal components of the ideal baseband signal branches on the basis of the obtained actual baseband signal and the signal system thereof; reproducing the ideal baseband signal, which is used to evaluating the actual baseband signal; establishing a correlation function between the actual baseband signal to be evaluated and the ideal baseband signal, and obtaining through corresponding calculations a series of quality evaluation indexes such as spurious transmission in the band and related loss, thereby enabling the evaluation of the quality of the radio frequency signal.

Abstract: A construction method for a (n,n(n?1),n?1) permutation group code based on coset partition is provided. The presented (n,n(n?1),n?1) permutation group code has an error-correcting capability of d?1 and features a strong anti-interference capability for channel interferences comprising multi-frequency interferences and signal fading. As n is a prime, for a permutation code family with a minimum distance of n?1 and a code set size of n(n?1), the invention provides a method of calculating n?1 orbit leader permutation codewords by On={?o1}?=1n?1(mod n) and enumerating residual codewords of the code set by Pn=CnOn={(l1)n?1On}={(rn)n?1On)}. Besides, a generator of the code set thereof is provided. The (n,n(n?1),n?1) permutation group code of the invention is an algebraic-structured code, n?1 codewords of the orbit leader array can be obtained simply by adder and (mod n) calculator rather than multiplication of positive integers.

Abstract: A method for evaluating the quality of a radio frequency signal for a satellite navigation system, the method comprising: sampling the payload radio frequency signal of a satellite to obtain an intermediate frequency signal, and filtering the signal; downconverting the filtered intermediate signal to obtain the corresponding actual baseband signal; generating the signal components of the ideal baseband signal branches on the basis of the obtained actual baseband signal and the signal system thereof; reproducing the ideal baseband signal, which is used to evaluating the actual baseband signal; establishing a correlation function between the actual baseband signal to be evaluated and the ideal baseband signal, and obtaining through corresponding calculations a series of quality evaluation indexes such as spurious transmission in the band and related loss, thereby enabling the evaluation of the quality of the radio frequency signal.

Abstract: A method for joint data-pilot tracking of navigation signal, including: multiplying a digital intermediate frequency signal with a local carrier to accomplish carrier removal; multiplying a signal after the carrier removal with a data baseband signal and a pilot baseband signal respectively to accomplish code removal; processing a signal after the code removal with integration-and-dump to obtain a coherent integration result of each branch; using the coherent integration results to accomplish data-bit flip detection and calculation of probability-weighting factor; acquiring a data-pilot joint carrier tuning-amount, and tuning the carrier numerically controlled oscillator by the carrier tuning-amount to realize data-pilot joint signal carrier tracking; and acquiring a data-pilot joint code tuning-amount, and tuning the code numerically controlled oscillator to realize baseband signal tracking.

Abstract: A construction method for a (n,n(n?1),n?1) permutation group code based on coset partition is provided. The presented (n,n(n?1),n?1) permutation group code has an error-correcting capability of d?1 and features a strong anti-interference capability for channel interferences comprising multi-frequency interferences and signal fading. As n is a prime, for a permutation code family with a minimum distance of n?1 and a code set size of n(n?1), the invention provides a method of calculating n?1 orbit leader permutation codewords by On={?o1}?=1n?1(mod n) and enumerating residual codewords of the code set by Pn=CnOn={(l1)n?1On}={(rn)n?1On)}. Besides, a generator of the code set thereof is provided. The (n,n(n?1),n?1) permutation group code of the invention is an algebraic-structured code, n?1 codewords of the orbit leader array can be obtained simply by adder and (mod n) calculator rather than multiplication of positive integers.

Abstract: The present invention provides a method for modulating a navigation signal, comprising: multiplying a data channel difference signal between upper and lower sidebands by a sine binary subcarrier to obtain an odd timeslot baseband signal of a branch Q, and multiplying a data channel sum signal of the upper and lower sidebands by a cosine binary subcarrier to obtain an odd timeslot baseband signal of a branch I of the data channel; multiplying a pilot channel difference signal between the upper and lower sidebands by the sine binary subcarrier to obtain an even timeslot baseband signal of the branch Q, and multiplying a pilot channel sum signal of the upper and lower sidebands by the cosine binary subcarrier to obtain an even timeslot baseband signal of the branch I; and performing QPSK modulation on the baseband signals of the branch I and branch Q to obtain a TD-AltBOC modulation signal.

Abstract: The present invention provides a method for modulating a navigation signal, comprising: multiplying a data channel difference signal between upper and lower sidebands by a sine binary subcarrier to obtain an odd timeslot baseband signal of a branch Q, and multiplying a data channel sum signal of the upper and lower sidebands by a cosine binary subcarrier to obtain an odd timeslot baseband signal of a branch I of the data channel; multiplying a pilot channel difference signal between the upper and lower sidebands by the sine binary subcarrier to obtain an even timeslot baseband signal of the branch Q, and multiplying a pilot channel sum signal of the upper and lower sidebands by the cosine binary subcarrier to obtain an even timeslot baseband signal of the branch I; and performing QPSK modulation on the baseband signals of the branch I and branch Q to obtain a TD-AltBOC modulation signal.