An apparatus comprising: a sensor adapted to generate higher-frequency output signal pulses, wherein the frequency of the signal pulses carries measurement information, a wireless field device comprising: a discrete input wireless transmitter adapted to detect discrete input signals, count the detected discrete input signals, and wirelessly transmit the count of discrete input signals to a control or monitoring system; and characterized in that the apparatus comprises: an electronic circuit for converting the higher-frequency output signal pulses from the sensor into lower-frequency input signals for the discrete input wireless transmitter, the circuit comprising: a differential amplifier adapted to amplify the sensor signals as a function of a frequency of the sensor signals; a digital comparator adapted to generate a square wave signal by comparing the amplified sensor signals to a fixed reference voltage; a digital frequency divider adapted to generate a lower-frequency signal by dividing the square wave signal; and a transistor switch adapted to generate the lower-frequency input signals for the discrete input wireless transmitter by switching as a function of the lower-frequency signal from the digital frequency divider. a sensor adapted to generate higher-frequency output signal pulses, wherein the frequency of the signal pulses carries measurement information, a wireless field device comprising: a discrete input wireless transmitter adapted to detect discrete input signals, count the detected discrete input signals, and wirelessly transmit the count of discrete input signals to a control or monitoring system; and characterized in that the apparatus comprises: an electronic circuit for converting the higher-frequency output signal pulses from the sensor into lower-frequency input signals for the discrete input wireless transmitter, the circuit comprising: a differential amplifier adapted to amplify the sensor signals as a function of a frequency of the sensor signals; a digital comparator adapted to generate a square wave signal by comparing the amplified sensor signals to a fixed reference voltage; a digital frequency divider adapted to generate a lower-frequency signal by dividing the square wave signal; and a transistor switch adapted to generate the lower-frequency input signals for the discrete input wireless transmitter by switching as a function of the lower-frequency signal from the digital frequency divider. a discrete input wireless transmitter adapted to detect discrete input signals, count the detected discrete input signals, and wirelessly transmit the count of discrete input signals to a control or monitoring system; and characterized in that the apparatus comprises: an electronic circuit for converting the higher-frequency output signal pulses from the sensor into lower-frequency input signals for the discrete input wireless transmitter, the circuit comprising: a differential amplifier adapted to amplify the sensor signals as a function of a frequency of the sensor signals; a digital comparator adapted to generate a square wave signal by comparing the amplified sensor signals to a fixed reference voltage; a digital frequency divider adapted to generate a lower-frequency signal by dividing the square wave signal; and a transistor switch adapted to generate the lower-frequency input signals for the discrete input wireless transmitter by switching as a function of the lower-frequency signal from the digital frequency divider. a differential amplifier adapted to amplify the sensor signals as a function of a frequency of the sensor signals; a digital comparator adapted to generate a square wave signal by comparing the amplified sensor signals to a fixed reference voltage; a digital frequency divider adapted to generate a lower-frequency signal by dividing the square wave signal; and a transistor switch adapted to generate the lower-frequency input signals for the discrete input wireless transmitter by switching as a function of the lower-frequency signal from the digital frequency divider.