Hi Adrian - If you use a file source with a throttle, then that section of your flowgraph will not drop samples. Using what Kevin wrote: The file source will "work" as fast as possible, so its output buffer will fill up quickly and any time samples are removed from it & so long as there is file data available the file source will keep the output buffer full -- and hence the throttle's input buffer will basically always be full. The throttle will pass every single sample through eventually, but at an average rate the matches its configuration. When presented with data in this fashion, the throttle will do a very good job of keeping the output sample rate close to that requested. Hence any dropped samples are happening downstream from the throttle. Hope this is useful! - MLD