dmi: apply filter to REF

dmi.py

@@ -14,9 +14,15 @@ def main():
 
     freq_sample = 1e6
     freq_base = 1088230e3
+    freq_ref = 1088100e3
     block_size = 4096
     throttle_factor = ceil(freq_sample/125e3)
 
+    # note: image band still goes through
+    freq_ref_abs = np.abs(freq_ref-freq_base)
+    ref_filter = LinearPhaseFilter(127, [freq_ref_abs-15e3, freq_ref_abs+15e3], pass_zero=False, fs=freq_sample)
+    meas_delay = Delay(block_size, ref_filter.delay())
+
     gui = GUI(freq_sample, freq_base, block_size)
     try:
         induction = InductionHeater("/dev/ttyUSB0", 350e3, 445e3)
@@ -26,7 +32,7 @@ def main():
                 gui.update_ref(spectrum, peak_freq, locked)
                 induction.set(tuning)
 
-            stabilizer = Stabilizer(freq_sample, block_size, 1088.1e6 - freq_base, stabilizer_cb)
+            stabilizer = Stabilizer(freq_sample, block_size, freq_ref-freq_base, stabilizer_cb)
             position_tracker = PositionTracker()
 
             sdr = SoapySDR.Device()
@@ -56,7 +62,7 @@ def main():
                             gui.update_meas(samples_meas)
 
                         if stabilizer.locked():
-                            position = position_tracker.input(samples_ref, samples_meas)
+                            position = position_tracker.input(ref_filter.input(samples_ref), meas_delay.input(samples_meas))
                             position_acc += np.mean(position)
                             if throttle == 0:
                                 gui.update_position(position_acc/throttle_factor)

noptica.py

@@ -195,7 +195,7 @@ class LinearPhaseFilter:
     def __init__(self, numtaps, *args, **kwargs):
         self.numtaps = numtaps
         self.coef = signal.firwin(numtaps, *args, **kwargs)
-        self.state = np.zeros(self.numtaps - 1)
+        self.state = np.zeros(self.numtaps - 1, dtype="complex64")
 
     def input(self, block):
         output, self.state = signal.lfilter(self.coef, [1.0], block, zi=self.state)
@@ -210,8 +210,8 @@ class Delay:
     def __init__(self, block_size, delay_amount):
         self.block_size = block_size
         self.delay_amount = delay_amount
-        self.output = np.zeros(block_size)
-        self.next = np.zeros(delay_amount)
+        self.output = np.zeros(block_size, dtype="complex64")
+        self.next = np.zeros(delay_amount, dtype="complex64")
 
     def input(self, block):
         assert(len(block) == self.block_size)