However, many of these devices and techniques are unsuitable for battery operated portable devices such as mobile telephones, or are incapable of meeting current RF design standards, such as the TETRA linearity standard, ETSI publication ETS 300 396-2; ???Trans-European Trunked Radio (TETRA);-Voice plus Data (V+D)???Part 2: Air Interface (AI)???; March 1996. [0004] Envelope elimination and restora