A data writing method for a block of a multi level cell NAND flash memory including upper page addresses and lower page addresses is provided, wherein a writing speed at the lower page addresses is higher than that at the upper page addresses. The tube is positioned south of a sucker rod. A relay node receives the RF signals representing the first set of data symbols in the first channel and transmits RF signals representing the first set of data symbols in the second channel. A value of the frequency element along a straight line on the logarithmic frequency spectrogram is voted onto a Hough plane. The output power level of the DC voltage provided by the base unit is controlled by power level controller such that the power level is sufficient to power all active load converters when commanded to do so by any of the active controllers, without generating excessive power that may be otherwise wasted.