iirj:用JAVA编写的高效IIR滤波器库

# iirj An IIR filter library written in JAVA. Highpass, lowpass, bandpass and bandstop as Butterworth, Bessel and Chebyshev Type I/II. It's based on the IIR1 library [https://github.com/berndporr/iir1] which in turn is based on Vinnie Falco's DSPFilters [https://github.com/vinniefalco/DSPFilters].  ## Usage `import uk.me.berndporr.iirj.*;` ### Constructor `Butterworth butterworth = new Butterworth();` ### Initialisation 1. Bandstop `butterworth.bandStop(order,Samplingfreq,Center freq,Width in frequ);` 2. Bandpass `butterworth.bandPass(order,Samplingfreq,Center freq,Width in frequ);` 3. Lowpass `butterworth.lowPass(order,Samplingfreq,Cutoff frequ);` 4. Highpass `butterworth.highPass(order,Samplingfreq,Cutoff frequ);` ### Filtering Sample by sample for realtime processing: ``` v = butterworth.filter(v) ``` ## Coding examples See the `*Test.java` files for complete examples for all filter types. Run them with `mvn test`. These test programs write the different impulse responses of the filters to text files. ## Installation Just run: `mvn install` to add it to your local maven respository or just point your project to Maven Central: ## Maven central Click on [](https://search.maven.org/search?q=g:%22uk.me.berndporr%22%20AND%20a:%22iirj%22) to get the latest version. ## Android Studio ``` dependencies { implementation group: 'uk.me.berndporr', name:'iirj', version: '1.3' } ``` ## Documentation * `mvn javadoc:javadoc` generates the JavaDocs * `mvn site` generates the web pages containing the documentation under `target/site` describing all commands in detail. ## Testing `mvn test` creates impulse responses in the subdirectories for the different filters: `target/surefire-reports`. To see the impulse and frequency responses run: ``` python3 ./plot_impulse_fresponse.py <filter> ``` where is <filter> is bessel, butterworth, chebyshevI or chebyshevII. The script DetectorTest uses a bandpass filter to detect the heartbeats of an ECG recording faking a matched filter which could be also seen as a 1st approximation of a wavelet. The heartrate is stored in hr.txt. Have fun /Bernd Porr [http://www.berndporr.me.uk]