## Filter Responses

Selecting a filter for a signal conditioning application can be difficult. However many filtering applications are similar and can be solved using a few optimised filter responses.

All filters, whether analogue or digital, change the signals passing through them. For any filter characteristic, the filter effect is strongly dependant on the kind of information contained in the signal.

We have a page that may be of interest that looks at the best filter for your Task.

Kemo has been manufacturing filtering systems for over 40 years. The many applications to which our filters have been put have resulted in a wide range of filter responses. Our Standard Response data sheet shows a range of filter responses which covers most needs, many of these are held in stock.

We feel that it is important to be able to compare the technical performance of different types of filter in a consistent way. Our "Filter Response Information Leaflets" use a uniform format to provide a complete picture of the filter characteristics in the amplitude, phase and time domains, independent of the intended application. This is of course no substitute for experimentation, and we encourage users to explore the performance of their system with filters fitted, to get an idea of not only of the suitability of the response itself, but also the signal quality aspects of the hardware (noise, linearity, offset etc) which are also related to the choice of the option response.

There are datasheets for the most used Kemo filter responses, each with a brief description of the type of filter.

Colour coded to our standard filter response sheet

**Anti-aliasing** Filter Response 01LP

Filter order and type: n=8 lowpass Basic stopband: -80dB at 1.5 times Fc

**8 Pole Butterworth** Filter Response 03LP

Filter order and type: n=8 lowpass Basic stopband: 48dB/octave (48dB at 2 times Fc)

**4 PoleButterworth** Filter Response 05LP

Filter order and type: n=4 lowpass Basic stopband: 24dB/octave (24dB at 2 times Fc)

**8 Pole Bessel** Filter Response 07LP

Filter order and type: n=8 lowpass Basic stopband: 48dB/octave (-13dB at 2 times Fc)

**4 Pole Bessel** Filter Response 09LP

Filter order and type: n=4 lowpass Basic stopband: 24dB/octave (-13dB at 2 times Fc)

**General Purpose** Filter Response 41LP

Filter order and type: n=8 lowpass Basic stopband: -82dB at 3 times Fc Linear Phase

8 Pole Butterworth BenchMaster 8. 8.03 Butterworth, Flat and Pulse

Filter order and type: n=8 lowpass Basic stopband: 48dB/octave (-52dB at 2 times Fc)

Filter set for BenchMaster 8.

8 Pole Butterworth BenchMaster 8. Filter Set:8.05 Butterworth , Flat, and Pulse

Filter order and type: n=4 lowpass Basic stopband: 24dB/octave (-26dB at 2 times Fc)

Filter set for BenchMaster 8.

Sharp filter for BenchMaster 8. Filter Set: 8.13 Butterworth, Flat, and Pulse

Filter order and type: n=8 lowpass Basic stopband: (-93dB at 2 times Fc)

Filter set for BenchMaster 8.

Notch Filter Sharp Q=10

Filter order and type: n=8 notch, stopband >-80dB

Optimised for 50 Hz and 60 Hz.

Available as 1200 Series Filter Modules

Filter Response: L1

Filter order and type: n=8 lowpass Basic stopband: -80dB at 1.5 times Fc

Filter for VBF 40 Series

Filter Response: L2

Filter order and type: n=8 lowpass Basic stopband: -116dB at 4.6 times Fc

Filter for VBF40 Series

Filter Response: 21LP

Filter order and type: n=6 lowpass Basic stopband: -102dB at 4 times Fc

Older filter response, used on pre 2005 21M systems.

Replaced by responses 37, 41 or 03.

Filter Response: 31LP

Filter order and type: n=6 lowpass Basic stopband: 36dB/octave (36dB at 2 times Fc)

6 Pole Butterworth, used on pre 2005 21M systems.

Replaced by responses 03 or 05.

Filter Response: 35LP

Filter order and type: n=8 lowpass Basic stopband: -85dB at 2 times Fc

Filter response option on old VBF10 and VBF 35 systems.

Replaced by BenchMaster 8.41 or VBF 40 series systems.

Filter Response: 37LP

Filter order and type: n=6 lowpass Basic stopband: -82dB at 3 times Fc

Lower delay filter available for compatability with older 21M systems.

Filter Response: 49LP

Filter order and type: n=8 lowpass Basic stopband: -77dB at 1.5 times Fc

Filter response option for old VBF10 and VBF 35 systems.

Replaced by BenchMaster 8.13 or VBF40 systems.

Filter Response: 79LP

Filter order and type: n=6 lowpass Basic stopband: -70dB at 3 times Fc

Older 6 pole filter. Replaced by response 41.

Filter Response: 85LP

Filter order and type: n=8 lowpass Basic stopband: -78dB at 2 times Fc

Higher frequency filter (>200kHz), semi-obsolete, newer components (from 2017)

make response 01 and 41 available at these frequencies.

Filter Response: 89LP

Filter order and type: n=8 lowpass Basic stopband: -74dB at 2.2 times Fc

Anti-alias typre filter, largly replaced by response 01 or 41.

Filter Response: Option 99

Filter order and type: n=4 lowpass Basic stopband: -68dB at 7.2 times Fc

4 pole anti-aliasing type, replaced by response 01 or 41.