mask2shift
Convert mask vector to shift for shift register configuration
Syntax
shift = mask2shift(prpoly,mask)
Description
shift = mask2shift(prpoly,mask)
returns
the shift that is equivalent to a mask, for a linear feedback shift
register whose connections are specified by the primitive polynomial prpoly
.
The prpoly
input can have one of these formats:
A binary vector that lists the coefficients of the primitive polynomial in order of descending powers
An integer scalar whose binary representation gives the coefficients of the primitive polynomial, where the least significant bit is the constant term
The mask
input is a binary vector whose length
is the degree of the primitive polynomial.
Note
To save time, mask2shift
does not check that prpoly
is
primitive. If it is not primitive, the output is not meaningful. To
find primitive polynomials, use primpoly
or
see [2].
For more information about how masks and shifts are related
to pseudonoise sequence generators, see shift2mask
.
Definition of Equivalent Shift
If A is a root of the primitive polynomial and m(A) is the mask
polynomial evaluated at A, the equivalent shift s solves the equation
As = m(A). To interpret the vector mask
as
a polynomial, treat mask
as a list of coefficients
in order of descending powers.
Examples
References
[1] Lee, J. S., and L. E. Miller, CDMA Systems Engineering Handbook, Boston, Artech House, 1998.
[2] Simon, Marvin K., Jim K. Omura, et al., Spread Spectrum Communications Handbook, New York, McGraw-Hill, 1994.
Version History
Introduced before R2006a
See Also
shift2mask
| log
| isprimitive
| primpoly