adnois

(tmp_for_tar/quad_min.doc/adnois.m)

Function Synopsis

[v,stddev] = adnois(u,db)

Help text

       [v,stddev] = adnois(u,db)

 Add db Dbs of Gaussian noise to u. The standard-deviation is

            -(db/20)   /---------
 stddev = 10         \/ cov(u(:))

 If db is nan or inf, v=u and stddev=0 are returned.

 See also : noislev

 Last modified: October 2000

Listing of function file tmp_for_tar/quad_min.doc/adnois.m

##       [v,stddev] = adnois(u,db)
##
## Add db Dbs of Gaussian noise to u. The standard-deviation is
##
##            -(db/20)   /---------
## stddev = 10         \/ cov(u(:))
##
## If db is nan or inf, v=u and stddev=0 are returned.
## 
## See also : noislev

## Author:        Etienne Grossmann  <etienne@isr.ist.utl.pt>
## Last modified: October 2000

function [v,stddev] = adnois(u,db)

if ! isfinite (db), v = u; stddev = 0; return; end

if prod(size(u)) == 0,
  error("adnois called with void signal");
end
n = randn(size(u));

dbn = 1;

## dbu = cov(u(:));
dbu = msq( u(:) ) - mean( u(find(!isnan(u(:)))) )^2 ;

stddev = 10^(-db/20)*sqrt(dbu) ; 

v = u+n*stddev;

% noislev(u,v)