The iirfilt_crcf object and family implement the infinite impulse response (IIR) filters. Also known as recursive filters, IIR filters allow a portion of the output to be fed back into the input, thus creating an impulse response which is non-zero for an infinite amount of time.

http://liquidsdr.org/doc/iirfilt/

liquid implements infinite impulse response (IIR) filter design for the five major classes of filters (Butterworth, Chebyshev type-I, Chebyshev type-II, elliptic, and Bessel) by first computing their analog low-pass prototypes, performing a bilinear -transform to convert to the digital domain, then transforming to the appropriate band type (e.g.

http://liquidsdr.org/doc/iirdes/

The iirdecim object family implements a basic interpolator with an integer output-to-input resampling ratio. It is similar to the firdecim family but with an infinite impulse response (recursive) filter performing the alias rejection.

http://liquidsdr.org/doc/iirdecim/

The iirinterp object implements an infinite impulse response (IIR) interpolator with an integer output-to-input resampling ratio. An example of the iirinterp interface is listed below. Listed below is the full interface to the iirinterp family of objects.

http://liquidsdr.org/doc/iirinterp/

This is the second of a two-part tutorial to derive bit error rate expressions for certain linear modulation schemes.

http://liquidsdr.org/blog/modem-ber-calc/

This tutorial demonstrates the functionality of a carrier phase-locked loop and introduces the iirfilt object.

http://liquidsdr.org/doc/tutorial-pll/

This is the main documentation page for liquid-dsp.

http://liquidsdr.org/doc/

This is the first of a two-part tutorial to simulate bit error rates for linear modulation schemes.

http://liquidsdr.org/blog/modem-ber-sim/