Exemple #1
0
def THDns(x, fs):
    """
    We take in rows of data and return a column of THDN measurements. 
    """

    # first, zero-mean

    rowcnt = len(x)
    meanxr = x.mean(1)
    meanxr.shape = (rowcnt, 1)
    xr = x - meanxr

    out = empty(len(x), Float)
    thdlist = []
    for i, xrow in enumerate(xr):
        
        thdn = 0.0
        enob = 0.0

        (thdnpy, A, B, C, w)  = pysinlesq.computeTHDN(xrow, int(fs))
        (thdnc, A, B, C, w)  = csinlesq.computeTHDN(xrow, int(fs))

        if thdnc < thdnpy:
            out[i] = thdnc
        else:
            out[i] = thdnpy

    return out
Exemple #2
0
def compWave(filename):
    f = tables.openFile(filename)

    num = 2
    t1 = f.root.A1.gain100.hpf1.sine
    r1 = [ (row['frequency'], row['data'])  for row in
               t1.where(t1.cols.sourcevpp > 0 )]

    x1= r1[num][1][:]


    fs = 32000
    N = len(x1)
    t =  r_[0.0:N]/ fs;

    (thdn, A1, B1, C1, w1) =  csinlesq.computeTHDN(x1, fs)
    x1m = (A1*cos(t*w1) + B1 * sin(t*w1) + C1)
    print "x1 thdn = ", thdn

    
    pylab.figure(1)
    pylab.plot(x1-x1m, label = "g=1")
    pylab.legend()
    pylab.grid()

    pylab.figure(2)
    pylab.plot(x1, 'r')
    pylab.plot(x1m, 'g')
    pylab.legend()
    pylab.grid()


    pylab.grid()

    test = []
    for i in range(100):
        test.append(mean(x1[(i*1000):((i+1)*1000)]))
Exemple #3
0
t = r_[0:1:(1/fs)]

n = array(randn(len(t))/2**14)


fc = 300
(b, a) = signal.bessel(1, fc/fs, btype='high')
print b, a
bits = 16

thdnf = []
thdn = []
wl =  r_[20:1000:50]
for w in wl:

    x = sin(w*t * pi * 2)
    y = x + n
    q = signal.lfilter(b, a, y)

    z = quant(q, bits)
    zu = quant(y, bits)
    thdn.append(sinlesq.computeTHDN(zu[2**10:], fs))
    thdnf.append(sinlesq.computeTHDN(z[2**10:], fs))


pylab.plot(wl, thdn, label = "unfiltered")
pylab.plot(wl, thdnf, label = 'filtered')
pylab.grid(True)
pylab.legend()
pylab.show()
Exemple #4
0
def plotmanyTHDns():
    f = tables.openFile(sys.argv[1])

    h = io.read_array(file('HPF-as-fir.dat'))


    ns = [2**13, 2**11,  2**9]
    plots = [2, 10, 19]

    for pnum, i in enumerate(plots):
        pylab.subplot( len(plots), 1, pnum+1)
        cl = list(colorlist)

        for n in ns:
            t = f.root.A3.gain10000.hpf0.sine
            x = array(t[i][0], dtype=Float64)

            y = (x - mean(x)) /2**15

            fs = 32000

            #print  "before", t[i][1], max(y), min(y),
            #y = signal.convolve(h, y, mode='same')
            #print  "after", max(y), min(y)

            N = len(y)  / n
            y.shape = (N, -1)

            
            errs = empty_like(y)
            thdns = []
            params = []
            for j, yrow in enumerate(y):

                thdn = 0.0
                enob = 0.0

                (thdn, A, B, C, w)  = csinlesq.computeTHDN(yrow, fs)
                errs[j] = thdnMeasure.getSineError(yrow, A, B, C, w, fs)

                thdns.append(thdn)
                params.append((A, B, C, w))

            worst = argmax(array(thdns))
            best = argmin(array(thdns))



            b = errs[best]
            w = errs[worst]
            print n, len(thdns)
            
            pylab.plot(arange(N, dtype=float)/(N-1), thdns,
                       color = cl[0], label = "length %d segments " % n)
            pylab.axhline(mean(thdns), color = cl[0], linestyle = '--', 
                       label = "_nolegend_")
            cl.pop(0)
            pylab.grid()
            pylab.title("Freq = %d " % t[i][1])
            pylab.legend()
            leg = pylab.gca().get_legend()
            ltext  = leg.get_texts()  # all the text.Text instance the legend
            pylab.ylabel('THD + n')
            pylab.setp(ltext, fontsize='xx-small')    # the legendfontsize


    pylab.show()