Just for sure, check your frequency scale settings. You can have frequence scale 50Hz while the visible line is 2000 Hz.
Anyway, noise signals are visible only on BB displays (which in fact is the spiky line on NB too). They have no distinct frequency. In DW, at least helos and shrimp are such contancts. With any sub or ship should give nice lines much sooner than you are able to see bump on spiky line.
|