In an attempt to get myself up to speed with PLLs I'm trying to implement Example 1 from this tutorial, in Python: https://wirelesspi.com/phase-locked-loop-pll-in-a-software-defined-radio-sdr/ (search for "Example 1")

I have output that is close to what the article shows, except that my cos_out[n] seems to be "leaning" to the left:

My phase-difference signale_D[n] is flipped vertically from what the tutorial shows:

I must be missing a - sign or have a sin() where I need cos() but I've checked and triple checked my code.

My code:

import numpy as np
k = 1
N = 15
K_p = 0.2667
K_i = 0.0178
K_0 = 1

samples = np.linspace(0, 100, 100, endpoint=False)
input_signal = np.cos(2*np.pi*(k/N)*samples + np.pi)

integrator_out = 0
phase_estimate = []
e_D = [] #phase-error output
e_F = [] #loop filter output
sin_out = []
cos_out = []

for n, sample_in in enumerate(input_signal):

    # phase detector
    try:
        e_D.append(sample_in * sin_out[n-1])
    except IndexError:
        e_D.append(0)
         

    #loop filter
    integrator_out += K_i * e_D[n]
    e_F.append(K_p * e_D[n] + integrator_out)


    #NCO
    try: 
        phase_estimate.append(phase_estimate[n-1] + K_0 * e_F[n])
    except IndexError:
        phase_estimate.append(K_0 * e_F[n])

    sin_out.append(-np.sin(2*np.pi*(k/N)*n + phase_estimate[n]))
    cos_out.append(np.cos(2*np.pi*(k/N)*n + phase_estimate[n]))

In an attempt to get myself up to speed with PLLs I'm trying to implement Example 1 from this tutorial, in Python: https://wirelesspi.com/phase-locked-loop-pll-in-a-software-defined-radio-sdr/ (search for "Example 1")

I have output that is close to what the article shows, except that my cos_out[n] seems to be "leaning" to the left:

My phase-difference signale_D[n] is flipped vertically from what the tutorial shows:

I must be missing a - sign or have a sin() where I need cos() but I've checked and triple checked my code.

My code:

import numpy as np
k = 1
N = 15
K_p = 0.2667
K_i = 0.0178
K_0 = 1

samples = np.linspace(0, 100, 100, endpoint=False)
input_signal = np.cos(2*np.pi*(k/N)*samples + np.pi)

integrator_out = 0
phase_estimate = []
e_D = [] #phase-error output
e_F = [] #loop filter output
sin_out = []
cos_out = []

for n, sample_in in enumerate(input_signal):

    # phase detector
    try:
        e_D.append(sample_in * sin_out[n-1])
    except IndexError:
        e_D.append(0)
         

    #loop filter
    integrator_out += K_i * e_D[n]
    e_F.append(K_p * e_D[n] + integrator_out)


    #NCO
    try: 
        phase_estimate.append(phase_estimate[n-1] + K_0 * e_F[n])
    except IndexError:
        phase_estimate.append(K_0 * e_F[n])

    sin_out.append(-np.sin(2*np.pi*(k/N)*n + phase_estimate[n]))
    cos_out.append(np.cos(2*np.pi*(k/N)*n + phase_estimate[n]))

In an attempt to get myself up to speed with PLLs I'm trying to implement Example 1 from this tutorial, in Python: https://wirelesspi.com/phase-locked-loop-pll-in-a-software-defined-radio-sdr/ (search for "Example 1")

I have output that is close to what the article shows, except that my cos_out[n] seems to be "leaning" to the left:

My phase-difference signale_D[n] is flipped vertically from what the tutorial shows:

I must be missing a - sign or have a sin() where I need cos() but I've checked and triple checked my code.

My code:

import numpy as np
k = 1
N = 15
K_p = 0.2667
K_i = 0.0178
K_0 = 1

samples = np.linspace(0, 100, 100, endpoint=False)
input_signal = np.cos(2*np.pi*(k/N)*samples + np.pi)

integrator_out = 0
phase_estimate = []
e_D = [] #phase-error output
e_F = [] #loop filter output
sin_out = []
cos_out = []
test_out = []

for n, sample_in in enumerate(input_signal):

    # phase detector
    try:
        e_D.append(sample_in * sin_out[n-1])
    except IndexError:
         e_D.append(0)
         

    #loop filter
    integrator_out += K_i * e_D[n]
    e_F.append(K_p * e_D[n] + integrator_out)


    #NCO
    try: 
        phase_estimate.append(phase_estimate[n-1] + K_0 * e_F[n])
    except IndexError:
        phase_estimate.append(K_0 * e_F[n])

    sin_out.append(-np.sin(2*np.pi*(k/N)*n + phase_estimate[n]))
    cos_out.append(np.cos(2*np.pi*(k/N)*n + phase_estimate[n]))

In an attempt to get myself up to speed with PLLs I'm trying to implement Example 1 from this tutorial, in Python: https://wirelesspi.com/phase-locked-loop-pll-in-a-software-defined-radio-sdr/ (search for "Example 1")

I have output that is close to what the article shows, except that my cos_out[n] seems to be "leaning" to the left:

My phase-difference signale_D[n] is flipped vertically from what the tutorial shows:

I must be missing a - sign or have a sin() where I need cos() but I've checked and triple checked my code.

My code:

import numpy as np
k = 1
N = 15
K_p = 0.2667
K_i = 0.0178
K_0 = 1

samples = np.linspace(0, 100, 100, endpoint=False)
input_signal = np.cos(2*np.pi*(k/N)*samples + np.pi)

integrator_out = 0
phase_estimate = []
e_D = [] #phase-error output
e_F = [] #loop filter output
sin_out = []
cos_out = []

for n, sample_in in enumerate(input_signal):

    # phase detector
    try:
        e_D.append(sample_in * sin_out[n-1])
    except IndexError:
        e_D.append(0)
         

    #loop filter
    integrator_out += K_i * e_D[n]
    e_F.append(K_p * e_D[n] + integrator_out)


    #NCO
    try: 
        phase_estimate.append(phase_estimate[n-1] + K_0 * e_F[n])
    except IndexError:
        phase_estimate.append(K_0 * e_F[n])

    sin_out.append(-np.sin(2*np.pi*(k/N)*n + phase_estimate[n]))
    cos_out.append(np.cos(2*np.pi*(k/N)*n + phase_estimate[n]))