help on PN sequence required

[47amadb]

pn sequence generator circuit

hello:
can some body help me in understanding Pseudo Random noise sequence"PN Seq". actually iam using it in my project for simulation of WCDMA transceiver model implementation in matlab.

 

[tibm]

pn sequence

Specify wat u wanna know abt pn-seq and de implementation in de prj(including prj title)

 

[47amadb]

pn sequence for digital communication

well i dont understand whether to use 4bits,5,10,14,16 or .... bits. for the computation and have you got code of PN sequence..
the second thing i dont know is that how the pn sequence works

 

[tibm]

pn code generator flip flop -patent

First know abt PN-seq and its uses by referring some digital communication book (for e.g : SImon Haykin,) .. then u might b in a god position to comprehend the need for the no. of bits

 

[nalino]

pn sequence with correlator

Ideally, random sequences should have a infinite length. But Pseudo-Random (PN) sequences are finite length sequences with semi-randomness in the elements in sequences. Some examples are M (or maximal length)-sequence, Gold sequence. They show good but not ideal correlation properties, i.e., auto-correlation for non-zero shifts and cross-correlation are selected to be minimal.

One way to generate PN sequences is use of polynomials. For example, these can be realized making a linear shift register and XOR adders.

Many communication theory books give a good explanations, please refer to them for further detail.

 

[sonysony_110]

cross correlation pn sequence

Pseudo Noise Sequences

The Pseudo Noise Sequence is zero-mean additive White Gaussian Noise (AWGN) has the same power spectral density GWGN (f) for all frequencies and non orthogonal sequence that consists of a deterministic and periodical signal, it acts as a noise like (but deterministic) carrier used for bandwidth spreading of the signal energy. The selection of a good code is important, because type and length of the code sets bounds on the system capability. The autocorrelation of a PN code has properties similar to those of white noise. It is usually generated by means of feed back shift register.

The shift register is made up by m-number of flip-flops (D-type flip-flop) connected in cascade to each other with common clock and the feed back is achieved by the use of logic circuit connected to certain tapes of the register to form a multi loop feed back circuit. With each clock pulse the state of each flip-flop is shifted to the next flip-flop. Then the output of logic circuit is fed back to the input of first flip-flop.



The PN sequence generated from feed back shift register is determined by:-

1-The number of stages in the shift register(number of flip flops)
2-Initial starting condition of the shift register
3-The number of taps in the feedback shift register

 

[surens]

pn sequence registers xor

Hi to all,
I am working in matlab simulink
I am simulating a Direct Sequence Spread sprectrum
it includes spreading, de-spreading,tracking and acquistion.
i am finding difficulty in acquistion.
VCO is not able to drive the PN sequence generator.
Can any one please help me