What is the pn code

The pn code is a coding sequence composed of 0s and 1s with autocorrelation properties similar to white noise. Its full English name is "Pseudo-Noise Code"; the pn code sequence is a commonly used address code ; The pn code is divided into long code and short code, which play different roles in CDMA.

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What is the pn code?

PN code (Pseudo-Noise Code) is a coding sequence composed of 0s and 1s with autocorrelation properties similar to white noise. The most well-known two-bit P-N Code is the maximum length The displacement register sequence, referred to as the m-sequence, has a length of 2 to the Nth power - 1 bit, and is generated by an m-level register with linear feedback. At the same time, pn codes are divided into long codes and short codes, which play different roles in CDMA.

Introduction

Pseudorandom (or pseudonoise, Pseudorandom Noise, PN) code sequence is a commonly used address code. Pseudo-random code sequence has basic characteristics similar to random sequences. It is a seemingly random but actually regular periodic binary sequence. If the transmitted data sequence is scrambled with complete randomness, the receiver cannot recover the original sequence. What is used in the actual system is a sufficiently random sequence. On the one hand, this random sequence is unrecognizable to non-target receivers. On the other hand, the target receiver can recognize and easily generate this random sequence synchronously.

Common PN offset refers to the PN code offset index. In the IS-95A CDMA system, the period of the PN short code is 32768 (that is, the 15th power of 2 = 32768 you see) chip. The short code The code is divided every 64 chips, so 512 (= 32768 / 64) short codes with different phases are obtained. These short codes are numbered from 0 to 511. This number is called the PN code offset index. Not all of these 512 PN Offset values ​​may be used. The step size (Pilot INC) needs to be determined based on the actual situation such as the size of the network before the PN Offset value that can be used is finally determined.

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