A transceiver for wirelessly transmitting process variables with a radio interface and a field device interface is provided. A torque applied to the shaft is measured based on a variation in magnetic characteristics of the first and the second magnetostrictive films; and a failure of the magnetostrictive torque sensor is detected based on a first difference between output values from the first and the second measurement coils and a second difference between output values from the third and the fourth measurement coils. A wavelength switching device selectively switches the selected wavelength of the wavelength selecting device. The backlight module can readily improve the corner vignette and enhanced with more evenly distributed brightness across the waveguide. The vest may include armor that is generally conformable to the waist shape of a wearer, which armor is insertable within the waist belt of the garment.