Andrew Warren wrote:
>
> Tjaart van der Walt <tjaart@wasp.co.za> wrote:
>
> > Here's the easiest way. You can do it in hardware or software.
> > Although it is not *truly* random, it is quite good indeed :
> >
> > Take a shift register (the longer the better), and tap two or three
> > of the stages. Add the taps (discard the carry - it is the same as
> > XORing) and feed back into the input of the shift register.
>
> Tjaart:
>
> This only works well if you pick the CORRECT two or three taps...
> Just choosing an arbitrary pair is unlikely to give a reasonably-long
> sequence.
>
> There are a couple of linear-feedback shift-register routines on my
> web page...

I agree. The ideal is to use one of the configurations for the P-code
generation for GPS pseudo random codes. (A couple of hundred days at
10.23Mbps before it repeats itself)

The normal C/A code is easy to generate with just two shift registers
(1023 bits before it repeats itself).

--
Friendly Regards

Tjaart van der Walt
mailto:tjaart@wasp.co.za
 _____________________________________________________________
| Another sun-deprived R&D Engineer slaving away in a dungeon |
|             WASP International  http://wasp.co.za           |
|             GSM and GPS value-added applications            |
|  Voice : +27-(0)11-622-8686   |   Fax : +27-(0)11-622-8686  |
|_____________________________________________________________|