| FIGURE 2 |
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| Fig 2—2a shows an incoming signal, which combines a periodic square wave and a much lower frequency hum. The input signal has two envelopes that follow the hum. The circuit separates these two envelopes and then subtracts them, yielding the waveform in 2b. A capacitor eliminates 2b's dc component, and the circuit splits the signal into the waveforms in 2c and 2d (inverting negative excursions to get the signal in 2c). Summing 2a with Fig 2c and Fig 2d yields the reconstructed pulse signal of 2e. |
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