Relation with Half-Band Filters and FIR Complex Half-Band Filter ?

• Parks-McClellan (Equiripple). ScopeFIR can design Filters, Hilbert Transformers, or Differentiators. Its “Simple Filter Specification Editor” allows you to easily design simple single-passband filters, and its “Advanced Filter Specification Editor” gives you access to the full capability of the Parks-McClellan algorithm by allowing you to enter any number of pass/stop bands, with any edge frequencies. ScopeFIR lets you enter frequencies in terms of the sample rate, and enter band response specifications in your choice of linear or dB units.
• Windowed Sinc. ScopeFIR can design lowpass, highpass, bandpass, or bandstop filters with user-specified band edge frequencies, and using any of its built-in data windows, including Dolph-Chebyshev, Blackman-Harris, Kaiser-Bessel (with choice of Alpha), Hamming, Hanning, andGaussian.
• Lth-Band. ScopeFIR can design special computationally efficient Lth-band (Nyquist) filters, including half-band filters.
• Raised Cosine. ScopeFIR automatically designs Raised Cosine and Root Raised Cosine filters (commonly used in digital data communications systems) with the specified rolloff factor and length.
• Maxflat. ScopeFIR can design lowpass FIR filters having a maximally flat passband.
• Cascaded Integrator-Comb. ScopeFIR can design CIC filters, which are widely used in hardware-based multirate applications.
• Import. ScopeFIR lets you import filters which have been designed with another application so you can analyze them using ScopeFIR’s powerful plotting and analysis capabilities, and to modify them using ScopeFIR’s powerful filter modification capabilities.
• Boxcar. ScopeFIR lets you fill the N taps with a constant to create a boxcar (or comb) filter.

Half Band filters are used in splitting a full band signal of bandwidth W into two eqaul subbands each with bandwidth W/2. Since the bandwidth is the subband signals is now half, the sampling rate can also be reduced by a factor of 2.