 MSO7000/DS7000 provides 4 practical filters (Low Pass Filter, High Pass Filter,
Band Pass Filter, and Band Stop Filter), which can filter the specified frequencies
in the signal by setting the bandwidth. You can use the :MATH<n>:FFT:SOURce
command to set or query the channel source of the filter.
 LPASs: indicates low pass filter, which only allows the signals whose frequencies
are smaller than the current cut-off frequency to pass.
 HPASs: indicates high pass filter, which only allows the signals whose
frequencies are greater than the current cut-off frequency to pass.
 BPASs: indicates band pass filter, which only allows the signals whose
frequencies are greater than the current cut-off frequency 1 and smaller than
the current cut-off frequency 2 to pass.
Note: The cut-off frequency 1 must be smaller than the cut-off frequency 2.
 BSTOP: indicates band stop filter, which only allows the signals whose
frequencies are smaller than the current cut-off frequency 1 or greater than the
current cut-off frequency 2 to pass.
Note: The cut-off frequency 1 must be smaller than the cut-off frequency 2.