FlexDDS is a multi-channel phase-coherent Radio Frequency source. The design directly addresses the needs of experimental physicists who want to control all signal parameters in real-time from a computer. Initially, a series of actions (like changes in amplitude or frequency, start of frequency sweeps, etc.) is compiled into commands which are then transferred to the FlexDDS-Rack via a USB link. Each time a (real-time asynchronous) trigger input is activated, FlexDDS-Rack executes one or several commands and waits for the next trigger event. There is no limit to the number of successive commands as they are loaded continuously from the host computer.
One outstanding feature of FlexDDS is its defined and known phase relationship between channels. For example, two channels can easily be set up to produce a Radio Frequency output at the same frequency and with an equal phase (or specified phase offset). Slightly detuning the frequency of one channel will then linearly increase the phase difference between the two channels.