How much baseband generator memory is needed in the signal generator to use basic mode waveforms?

The amount of memory that is needed depends on how many waveform files you need to have in the instrument memory at one time. Each individual waveform file is fairly small because these are short files that only last a few seconds before they repeat. A GPS waveform is about 800 K-samples, GLONASS is 100 K-samples, and Galileo is 240 K-samples.