hf model doing something sensible, some progress on improving SNR set up butstill needs some work

git-svn-id: https://svn.code.sf.net/p/freetel/code/codec2-dev@1671 01035d8c-6547-0410-b346-abe4f91aad63
refactoring hf model

git-svn-id: https://svn.code.sf.net/p/freetel/code/codec2-dev@1672 01035d8c-6547-0410-b346-abe4f91aad63