comms.py 文件源码

def diff_decode(x):
    """Decode phase differential baseband signal.

    :param x: complex baseband differential data to decode
    :returns: decoded complex baseband data of length len(x)-1

    >>> import arlpy
    >>> d1 = arlpy.comms.random_data(100, 4)
    >>> qpsk = arlpy.comms.psk(4)
    >>> x = arlpy.comms.modulate(d1, qpsk)
    >>> y = arlpy.comms.diff_encode(x)
    >>> z = arlpy.comms.diff_decode(y)
    >>> d2 = arlpy.comms.demodulate(z, qpsk)
    >>> arlpy.comms.ser(d1, d2)
    0.0
    """
    x = _np.asarray(x)
    y = _np.array(x)
    y[1:] *= x[:-1].conj()
    return y[1:]