Add plot_phase_spectrum().

applications/lofar2/model/rtdsp/plotting.py

@@ -137,7 +137,7 @@ def plot_iir_filter_analysis(b, a, fs=1.0, whole=False, Ntime=100, step=False, l
     return z, p, k
 
 
-def plot_spectra(fn, HF, fs=1.0, fLim=None, dbLim=None):
+def plot_spectra(fn, HF, fs=1.0, fLim=None, dbLim=None, aLim=None):
     """Plot spectra for power, magnitude, phase, real, imag
 
     Input:
@@ -189,6 +189,34 @@ def plot_spectra(fn, HF, fs=1.0, fLim=None, dbLim=None):
     plt.xlabel(flabel)
     if fLim:
         plt.xlim(fLim)
+    if aLim:
+        plt.ylim(aLim)
+    plt.grid(True)
+
+
+def plot_phase_spectrum(fn, HF, fmt='r', fs=1.0, fLim=None, aLim=None):
+    """Plot phase spectrum
+
+    Use fLim and aLim to zoom in, to see slope in pass band. Note that -pi =
+    pi.
+
+    Input:
+    . fn: normalized frequency axis for HF (fs = 1)
+    . HF: spectrum, e.g. frequency transfer function HF = DTFT(h)
+    . fmt: curve format string
+    . fs: sample frequency in Hz
+    """
+    f = fn * fs  # scale fn by fs
+    flabel = 'Frequency [fs = %f]' % fs
+
+    plt.plot(f, np.unwrap(np.angle(HF)), fmt)
+    plt.title('Phase spectrum')
+    plt.ylabel('Pase [rad]')
+    plt.xlabel(flabel)
+    if fLim:
+        plt.xlim(fLim)
+    if aLim:
+        plt.ylim(aLim)
     plt.grid(True)