A method and apparatus is disclosed for performing blind source separation using convolutive signal decorrelation. An organic light emitting device including the compound, improves the driving voltage, the emission efficiency, and the color purity of an organic light emitting display. In order to obtain a spin valve structure having a very good GMR effect the method comprises the following specific steps: oxidation of the ferromagnetic material of the sense layer; deposition of aluminium on the oxidized ferromagnetic material; oxidation of the deposited aluminium using oxygen from the oxidized ferromagnetic material. A hose may be moved freely around the yard, being guided by the retractable hose guide, thus avoiding damage either to the hose or to the landscaping.