The present invention relates to a method for the modification of calcium carbonate fillers to improve their acid-tolerant property and to make their effective use in papermaking of high-lignin-content deinked pulp derived from recycled newspaper. In specific embodiments, this memory system contains a memory device which includes a clock distribution circuit and an oscillator circuit which can generate a frequency, wherein a change in the frequency is indicative of a timing drift of the clock distribution circuit. The variable frequency drive device has a variable frequency controller that has an input for receiving AC power and an output for providing electrical signals that control the operational speed of high-torque, permanent magnet motor. A wire network model is then initialized, and iteratively improved by simulating an impulse response of the wire network model and adjusting the wire network model to reduce differences between the simulated impulse response and estimated network impulse response.