generate broadband signal in time domain

zhiim · Jan 4, 2025 · 090a511 · 090a511
1 parent 3863dd7
commit 090a511
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Showing 2 changed files with 211 additions and 37 deletions.
diff --git a/doa_py/arrays.py b/doa_py/arrays.py
@@ -1,4 +1,5 @@
 from abc import ABC
+from typing import Literal
 
 import numpy as np
 
@@ -94,6 +95,7 @@ def received_signal(
         nsamples=100,
         amp=None,
         unit="deg",
+        use_cache=False,
         **kwargs,
     ):
         """Generate array received signal based on array signal model
@@ -113,6 +115,8 @@ def received_signal(
             amp: The amplitude of each signal, 1d numpy array
             unit: The unit of the angle, `rad` represents radian,
                 `deg` represents degree. Defaults to 'deg'.
+            use_cache (bool): If True, use cache to generate identical signals
+                (noise is random). Default to `False`.
             **kwargs: Additional parameters for generating broadband signal,
                 check `gen` method of `BroadSignal`.
         """
@@ -121,22 +125,34 @@ def received_signal(
 
         if isinstance(signal, BroadSignal):
             received = self._gen_broadband(
-                signal,
-                snr,
-                nsamples,
-                angle_incidence,
-                amp,
+                signal=signal,
+                snr=snr,
+                nsamples=nsamples,
+                angle_incidence=angle_incidence,
+                amp=amp,
+                use_cache=use_cache,
                 **kwargs,
             )
         if isinstance(signal, NarrowSignal):
             received = self._gen_narrowband(
-                signal, snr, nsamples, angle_incidence, amp
+                signal=signal,
+                snr=snr,
+                nsamples=nsamples,
+                angle_incidence=angle_incidence,
+                amp=amp,
+                use_cache=use_cache,
             )
 
         return received
 
     def _gen_narrowband(
-        self, signal: NarrowSignal, snr, nsamples, angle_incidence, amp
+        self,
+        signal: NarrowSignal,
+        snr,
+        nsamples,
+        angle_incidence,
+        amp,
+        use_cache=False,
     ):
         """Generate narrowband received signal
 
@@ -151,7 +167,9 @@ def _gen_narrowband(
             signal.frequency, angle_incidence, unit="rad"
         )
 
-        incidence_signal = signal.gen(n=num_signal, nsamples=nsamples, amp=amp)
+        incidence_signal = signal.gen(
+            n=num_signal, nsamples=nsamples, amp=amp, use_cache=use_cache
+        )
 
         received = manifold_matrix @ incidence_signal
 
@@ -167,9 +185,44 @@ def _gen_broadband(
         nsamples,
         angle_incidence,
         amp,
+        use_cache=False,
+        calc_method: Literal["fft", "delay"] = "fft",
+        **kwargs,
+    ):
+        assert calc_method in ["fft", "delay"], "Invalid calculation method"
+
+        if calc_method == "fft":
+            return self._gen_broadband_fft(
+                signal=signal,
+                snr=snr,
+                nsamples=nsamples,
+                angle_incidence=angle_incidence,
+                amp=amp,
+                use_cache=use_cache,
+                **kwargs,
+            )
+        else:
+            return self._gen_broadband_delay(
+                signal=signal,
+                snr=snr,
+                nsamples=nsamples,
+                angle_incidence=angle_incidence,
+                amp=amp,
+                use_cache=use_cache,
+                **kwargs,
+            )
+
+    def _gen_broadband_fft(
+        self,
+        signal: BroadSignal,
+        snr,
+        nsamples,
+        angle_incidence,
+        amp,
+        use_cache=False,
         **kwargs,
     ):
-        """Generate broadband received signal
+        """Generate broadband received signal using FFT model
 
         `azimuth` and `elevation` are already in radians
         """
@@ -184,6 +237,8 @@ def _gen_broadband(
             n=num_signal,
             nsamples=nsamples,
             amp=amp,
+            use_cache=use_cache,
+            delay=None,
             **kwargs,
         )
 
@@ -209,6 +264,54 @@ def _gen_broadband(
 
         return received
 
+    def _gen_broadband_delay(
+        self,
+        signal: BroadSignal,
+        snr,
+        nsamples,
+        angle_incidence,
+        amp,
+        use_cache=False,
+        **kwargs,
+    ):
+        """Generate broadband received signal by applying delay
+
+        `azimuth` and `elevation` are already in radians
+        """
+        if angle_incidence.ndim == 1:
+            num_signal = angle_incidence.size
+        else:
+            num_signal = angle_incidence.shape[1]
+
+        # calculate time delay
+        angle_incidence = np.reshape(angle_incidence, (2, -1))
+        cos_cos = np.cos(angle_incidence[0]) * np.cos(angle_incidence[1])
+        sin_cos = np.sin(angle_incidence[0]) * np.cos(angle_incidence[1])
+        sin_ = np.sin(angle_incidence[1])
+        time_delay = (
+            1 / C * self.array_position @ np.vstack((cos_cos, sin_cos, sin_))
+        )
+
+        received = np.zeros((self.num_antennas, nsamples), dtype=np.complex128)
+
+        for i in range(self.num_antennas):
+            received[i, :] = np.sum(
+                signal.gen(
+                    n=num_signal,
+                    nsamples=nsamples,
+                    amp=amp,
+                    use_cache=use_cache,
+                    delay=time_delay[i, :],
+                    **kwargs,
+                ),
+                axis=0,
+            )
+
+        if snr is not None:
+            received = self._add_awgn(received, snr)
+
+        return received
+
     def _add_awgn(self, signal, snr_db):
         sig_pow = np.mean(np.abs(signal) ** 2, axis=1)
         noise_pow = sig_pow / 10 ** (snr_db / 10)