What you are looking for is the decimate vi.
In your case probably the
Decimate (continuous) VI
Owning Palette: Signal Operation VIs
Requires: Full Development System
Continuously decimates the input sequence X by the decimating factor and the averaging Boolean control. Wire data to the X input to determine the polymorphic instance to use or manually select the instance.
Read your data in blocks , pass it through the decimate vi and work with the reduced data.
If you are not directly storing the smaller data blocks, try to allocate the data arrays first and use the inplace structure to avoid to run out of memory due to continous memory reallocation of the increasing array.
Greetings from Germany
Henrik
LV since v3.1
“ground” is a convenient fantasy
'˙˙˙˙uıɐƃɐ lɐıp puɐ °06 ǝuoɥd ɹnoʎ uɹnʇ ǝsɐǝld 'ʎɹɐuıƃɐɯı sı pǝlɐıp ǝʌɐɥ noʎ ɹǝqɯnu ǝɥʇ'