LSFIR.py 文件源码

def lpfls(N,wp,ws,W):
    M = (N-1)/2
    nq = np.arange(0,2*M+1)
    nb = np.arange(0,M+1)
    q = (wp/np.pi)*np.sinc((wp/np.pi)*nq) - W*(ws/np.pi)*np.sinc((ws/np.pi)*nq)
    b = (wp/np.pi)*np.sinc((wp/np.pi)*nb)
    b[0] = wp/np.pi
    q[0] = wp/np.pi + W*(1-ws/np.pi) # since sin(pi*n)/pi*n = 1, not 0
    b = b.transpose()

    Q1 = ln.toeplitz(q[0:M+1])
    Q2 = ln.hankel(q[0:M+1],q[M:])
    Q = Q1+Q2

    a = ln.solve(Q,b)
    h = list(nq)
    for i in nb:
        h[i] = 0.5*a[M-i]
        h[N-1-i] = h[i]
    h[M] = 2*h[M]
    hmax = max(np.absolute(h))
    for i in nq:
        h[i] = (8191/hmax)*h[i]
    return h