EchoFilter uses the soundcard of a PC to process income audio signals in real-time. The latest version incorporates a powerful programmable audio filter as well as a frequency counter up to 16 kHz with a 7 Hz resolution. The filter bandwidth can go down to 20 Hz and can extract signals and sounds from the audio signal that may normally be close to inaudible. Is can also be used the remove noise and unwanted sounds form the audio signal. The real-time spectrum analyzer and spectrogram gives the user an excellent visualization of the audio. The program also includes an automatic gain control, frequency shifting, graphic equalizer, audio compressor and expander, wave file player and recorder and noise reduction filters.

It is intended for radio HAMS, hobbyists, researchers, scientists and students in the DSP field. Uses include weak signal detection, surveillance, audio cleanup, SETI operations, etc.

EchoFilter 3
This version is a total redesign and includes many new features. For example, a high-resolution spectrum analyzer, spectrogram, frequency shifting, expander, equalizer etc. For more information, see EchoFilter 3 features.
You may download the demo version and try it out. For a list of demo limitations, see the versions page.
Want to nominate a new EchoFilter 3 feature? Visit the features nominations page !

EchoFilter 2
EchoFilter was originally developed as a general-purpose real-time digital audio filter. This version incorporates a programmable audio filter as well as a frequency counter up to 10 kHz with a 10 Hz resolution. A Real-time spectrum analyzer helps to visualize the incoming audio signal. A Variety of function plots is available to display certain properties of the filtered signal over time. See EchoFilter 2 features. Version 2 is absolutely free. You may download and use the free version.

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