An electrified cylindrical lock having a reversible solenoid that can be easily changed over between fail safe and fail secure. The overhead electrode has a capacitance such that the overhead electrode and the plasma formed in the chamber at the desired plasma ion density resonate together at an electrode-plasma resonant frequency, the frequency of the generator being at least near the electrode-plasma resonant frequency. 7 or less of the return amount of the artificial urine in the urination region when the artificial urine is dropped and absorbed in the urination region. The three or more additional impedance measurements are made at a second frequency different from the first frequency. The apparatus includes an encoder for encoding a redundant coded picture corresponding to a source picture by selecting individual blocks in the source picture for inclusion into the redundant coded picture.