import scipy as sp
import numpy as np



def chunk_samples(samples, num_rows):
    return samples.reshape((samples.shape[0]//num_rows, num_rows))


def db(x):
    return 10*np.log10(x)


def quad_demod(samples):
    return 0.5*np.angle(samples[:-1] * np.conj(samples[1:]))


def lowpass(data, f_cutoff, f_s):
    nyq = 0.5*f_s
    normal_cutoff = f_cutoff/nyq
    b, a = sp.signal.butter(2, normal_cutoff, btype="low", analog=False)
    y = sp.signal.lfilter(b, a, data)
    return y


def sdr_bandpass(data, f_pass, f_cutoff, extent_MHz):

    lower_extent = extent_MHz[0]*1E6
    upper_extent = extent_MHz[1]*1E6
    extent_range = upper_extent - lower_extent

    normal_pass = (f_pass - lower_extent)/extent_range
    normal_cutoff = (f_cutoff - lower_extent)/extent_range

    b, a = sp.signal.butter(2, (normal_pass, normal_cutoff), btype="bandpass", analog=False)
    y = sp.signal.lfilter(b, a, data)
    return y