# How to record and replay the center frequency when file_sink?

Workflow as below:

When file_source after file_sink,center frequency is not recorded and replay in gui_sink.

How to record and replay the center frequency when file_sink?

• The file sink actually has nothing to do with this. You get the exact same problem if you just wire the USRP source directly to the GUI sink. It's because you didn't set the center frequency on the GUI sink Oct 5 at 13:03
• Even you set the center frequency,file sink doesn't record it.That's the key problem. Oct 5 at 13:18
• Type in the same center frequency when you load the file? Oct 5 at 13:24
• @user253751,I will not ask this question if I can remember hundreds frequencies per hour. Oct 5 at 13:28
• You've got a fundamental misunderstanding what the file sink or source do. They just deal with the raw time samples. "Frequency" is not among the things they save. As @user253751 says, this isn't special about these sinks either: sample flows are just that, samples. There's no "interpretation" like "this is at frequency XYZ" inherent to these sample flows. Oct 5 at 13:59