The DSPFilter program is a digital filter processing (DSP) program that allows your computer to filter the audio input (microphone) with one of several filters and then output it to the computer speakers. The program has been designed to work with communications receivers for professional and amateur use. Using the spectrum display you can drag a filter onto a signal of interest (SOI) and filter that signal with either a fixed bandpass filter, a variable bandpass filter, or a notch filter. In addition, one of two noise reduction filters are available to filter the total spectrum.

The installation program has default user settings to initialize the program filters and controls. There are no other setups needed. A configuration file saves all program controls and settings. When the program is started the configuration file is read and the last program settings is used to set the controls.

The main operator display is a graphical display of the input audio spectrum. Depending on the Spectrum Width setting the display will show frequency ranges from 10 Hz to 5512 Hz, or 10 Hz to 2756 Hz, or 10 Hz to 1378 Hz.

The display can also show the first 512 samples of each input buffer in the time domain (oscilloscope). The screen display control switches between the two types of displays.

DSP Filter Features:
1. Audio Digital Filter
* Two bandpass filters
* Three notch filters
* Two noise filters
* All filters cascadable
2. Graphical setting of filter center frequency and bandwidth
* Drag vertical lines on top of signal
3. Microphone input, speaker output:
* Mono, 5 kHz bandwidth:
4. File record and playback filtered audio:
* Simultaneous operation
5. Frequency or time display

The license of this software is Freeware, you can free download and free use this audio utility software.