Zurich Instruments offers a unit for arithmetic operations on the results of lock-in amplifier and boxcar measurements. The UHF Arithmetic Unit (AU) is included with every UHF instrument; additional upgrades such as the UHF-BOX and UHF-PID options extend the instrument's functionalities even further.
The 4 arithmetic units enable real-time operations on the measurement results of demodulators, boxcar units, and auxiliary input connectors as input parameters. On the UHFLI, for example, 2 signal inputs and 8 dual-phase demodulators make it possible to combine more than 50 different input parameters. Supported operations include addition, subtraction, multiplication, division, scaling, as well as absolute-value and phase-angle calculation of complex numbers in the form X1 + i*Y2.