METHOD FOR MODULATING NAVIGATION SIGNAL

摘要

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. The present invention can implement transmission of different navigation services at two adjacent frequency bands, and each navigation service comprises a data channel and a pilot channel. The navigation signal of each sub-band may be received independently, or signals of the upper and lower sidebands may be jointly received to obtain high-precision navigation performance.

主权项

1. A method for modulating navigation signal, the method comprising the following steps:
1) dividing frequency of a control clock CLK0 to obtain a pseudo-code generating drive clock CLK1 and a time division multiplexing (TDM) control clock CLK2, where, a frequency of the control clock CLK0 is four times that of a binary subcarrier, a frequency of the pseudo-code generating drive clock CLK1 is ½ of a code rate, and a frequency of the TDM control clock CLK2 is equivalent to the code rate; 2) driving the CLK1 to generate pseudo-code cBD of a data channel of an upper sideband, pseudo-code cAD of a data channel of a lower sideband, and pseudo-code cP of a pilot channel; driving the CLK0 to generate a binary sine subcarrier SCB, sin and a binary cosine subcarrier SCB, cos; 3) modulating the CAD by a lower sideband dA to generate a baseband signal component CA of the data channel of the lower sideband; modulating the CBD by an upper sideband waveform dB to generate a baseband signal component CB of the data channel of the upper sideband; 4) modulating the subcarriers, which comprising:
(4.1) negating the CA and adding to the CB, and multiplying with the SCB, sin to get a signal component of data channel at Q branch; adding the CA to the CB and multiplying with the SCB, cos to get a signal component of data channel at I branch; multiplying the CP by 2 and then multiplying with the SCB, cos to get a signal component of the pilot channel at I branch; and(4.2) when the CLK2 is in a time slot of odd chip, allowing the signal component of the data channel at Q branch to be a signal component of a baseband signal at Q branch, and allowing the signal component of the data channel at I branch to be a signal component of a baseband signal at I branch; when CLK2 is in a time slot of even chip, allowing zero signal to be the signal component of the baseband signal at Q branch, and allowing the signal component of the pilot channel at I branch to be the signal component of the baseband signal at I branch; and 5) modulating a sine phase carrier by the signal component of the baseband signal at Q branch, modulating a cosine phase carrier by the signal component of the baseband signal at I branch, and combining the modulation result of the two branches to obtain a modulated radio frequency signal.