> In most practical cases, the result of the Gardner calculation should be
> thought of as little more than a "go left" or "go right" indication.
> Trying to use the actual magnitude of the result, rather than just its
> sign, works fine in a sterile noiseless model. In the real noisy world
> the impairments mean trying to scale the adjustment with the magnitude
> of the result can be less than spectacularly successful.
>

And, that is also why the Gardener TED works for a wide range of
modulation schemes including QAM. Anyways, you might want to consult
"Digital Communication Receivers" by H. Meyr et. al, for a more in-
depth treatment of this subject.

Vijay.