DIY Radar 20Khz Audio Filter

DIY Radar 20KHz Low Pass Audio Filter

This module is used in the MIT OpenCourseWare (Open Course Ware) Radar program to act as a low pass filter before processing the audio output of the high frequency RF mixer. Sometime referred to a as the “video filter”, this is a multi-pole Butterworth low–pass active filter that roles off heavily at 20 Khz, acting as a Nyquist filter as referred to by some.  This is typically the module that you have to build yourself or use a breadboard but not any more!

This is a completed, tested audio filter guaranteed to roll off at 20Khz, or buy just the blank PCB  and create you own filter by changing the values.

This module uses RCA “Phono” connectors for the input and output signals.

Below is the schematic with values calculated for a 20Khz, 6db/octave roll-off.

PDF of Schematic

Get your MIT Open Course Ware Radar project off the ground in hours, not days!

Additional information