creating a realtime analog RF waveform having periodic waveform components by digital-to-analog conversion of a packet of data using a digital-to-analog converter, the packet having a header and a time stamp such that the timing of the generation of the periodic components of the waveform is controlled by packet contents to nanosecond accuracies greater than the accuracy associated with frame timing accuracies;

generating the packets using non-realtime off-the-shelf components; and,

gating the packets to the digital-to-analog converter using a realtime interface including a precision clock having nanosecond accuracy greater than an accuracy associated with frame timing, such that the analog RF waveform is created by coupling the contents of the packet to the digital-to-analog converter when the time stamp of the header in the packet matches the current time from the realtime precision clock, thus to create the start of the periodic waveform to said nanosecond accuracy and to create each of the following periodic analog RF waveform components with nanosecond accuracy, whereby timing errors of the off-the-shelf components are not dominant.