1. An apparatus comprising: a pseudo random signal generator to provide a first signal to a first electrode, to vary a frequency of the first signal, wherein the first electrode is configured to form a first capacitance with a second electrode; a demodulator to receive the first signal from the second electrode, and to receive, from the pseudo random signal generator, a reference signal indicative of the frequency of the first signal, wherein the reference signal is used to select a passing frequency used by the demodulator to pass a portion of the first signal from the second electrode; and detection circuitry to detect, using a demodulated first signal, a change in the first capacitance of the first electrode and the second electrode, wherein the change in the first capacitance is responsive to a presence of a first input object proximate the first electrode and second electrode, the detection circuitry further to detect, using another demodulated first signal, a change in a second capacitance of a third electrode and a fourth electrode, wherein the change in the second capacitance is responsive to a presence of a second input object proximate the third electrode and the fourth electrode, wherein the presence of the first input object is concurrent with the presence of the second input object, and wherein the other demodulated first signal corresponds to the first signal provided to the third electrode by the pseudo random signal generator, the third electrode configured to form the second capacitance with the fourth electrode.