Instruction Manual

86
Notch Filter
The notch filter can be set to OFF, 50 Hz, or 60 Hz.
OFF is the normal setting.
Use the notch filter when you hear a buzzing sound from your headphones or speakers, such as the sound
of a power pole transformer or a compressor in a vending machine.
For details on configuring the notch filter, see "Filter setting" under "4-7 Explanation of Equipment
Settings and Operations" on p. 42.
Below is a brief description of the different types of filters.
In addition to the high-pass filter and the low-pass filter, which cut off the frequency components above or
below a certain level, there are various filters such as the band-pass filter (BPF) that passes only a certain
frequency band, or the band rejection filter (BRF) that does not pass only a certain frequency band to some
extent (this filter does not remove the relevant frequency band completely and therefore is not called a
"band cut filter"). The notch filter (NF) is one type of band rejection filter that handles a narrower band. A
comb filter is an aggregation of multiple notch filters.
As shown above, the notch filter is a filter that cuts only the components in a certain frequency band.
Since this leak detector uses a combination of multiple notch filters, strictly speaking this function should
be called "comb filter," but here the term "notch filter" is used for convenience.
Five notch filters are applied at intervals of either 50 Hz or 60 Hz.
In 50 Hz band mode, the filters cut the harmonics in the 50, 100, 150, 200, and 250 Hz bands.
In 60 Hz band mode, the filters cut the harmonics in the 60, 120, 180, 240, and 300 Hz bands.
If the pre-amplifier seems to pick up harmonics in the 50 and 60 Hz commercial bands, try using this
function to detect the leakage location.
Volume
Volume
Volume
Volume
Volume
Volume
Freq.
Low
High
High-pass
Freq.
Low
High
Low-pass
Freq.
Low
High
Band-pass
Volum
Freq.
Low
High
Original frequency
Freq.
Low
High
Band rejection
Freq.
Low
High
Notch
Freq.
Low
High
Comb