For engineers developing audio test applications, the LabVIEW FPGA module is a graphical development environment for easily implementing or prototyping S/PDIF and other communication protocols on the 7831R reconfigurable I/O hardware. Unlike custom hardware or ASICs using VHDL, the LabVIEW FPGA module allows you to develop, test and debug new functionality quickly without the need for specialized development tools.

Quadrature amplitude modulation (QAM) is the name of a family of digital modulation methods and a related family of analog modulation methods widely used in modern telecommunications to transmit information.   It conveys two analog message signals, or two digital bit streams, by changing (modulating) the amplitudes of two carrier waves, using the amplitude-shift keying (ASK) digital modulation scheme or amplitude modulation (AM) analog modulation scheme. The two carrier waves of the same frequency are out of phase with each other by 90°, a condition known as orthogonality or quadrature.  The transmitted signal is created by adding the two carrier waves together.  At the receiver, the two waves can be coherently separated (demodulated) because of their orthogonality property.  Another key property is that the modulations are low-frequency/low-bandwidth waveforms compared to the carrier frequency, which is known as the narrowband assumption.