In one embodiment, a method includes initiating an acquisition of a first signal from an electrode of a touch sensor according to an acquisition frequency of the touch sensor. The method also includes reversing, with a controller, a polarity of the first signal to produce a second signal. The method also includes storing a first modulated signal at an end of the acquisition of the first signal, where the first modulated signal includes the second signal as modulated by one or more third-party signals during the acquisition of the first signal.