作者yellowsky (自伤..)
看板EarthScience
标题[问题] GPS signal
时间Tue May 13 21:11:13 2003
关於GPS signals的东东
我看到书里面的文章写到：
Each GPS satellite transmits two spread spectrum, L-band carrier signals--
an L1 signal with carrier frequency f1=1575.42MHz and an L2 signal with
carrier frequency f2=1227.6MHz.
These two frequencies are integral multiples
f1=1540*f0 and f2=1200*f0 of a base frequency f0=1.023MHz.
为什麽上面所列的L1 and L2 signals 会和f0有一个倍数关系？
而f0=1.023MHz作为一个base frequency是有何用意？
The L1 signal from each satellite uses binary phase-shift keying(BPSK),
modulated by two pesudorandom noise (PRN) codes in phase quadrature, designated
as the C/A-code and P-code. The L2 signal from each satellite is BPSK modulated
by only the P-code.
What is "binary phase-shift keying(BPSK)"??
What is "pesudorandom noise(PRN)"??
What are "C/A-code" and "P-code"??
为何L1 signal有 C/A-code and P-code来modulate, 但对於L2 signal却只有P-code??
thanks!!
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