From cedbdf3b93def9cf6b8b4b481b0c55a6a4daa52f Mon Sep 17 00:00:00 2001
From: pravirkr <pravirka@gmail.com>
Date: Fri, 27 Oct 2023 07:37:46 +0530
Subject: [PATCH] improved simulated signal

---
 kalman_detector/efficiency.py |  5 +++--
 kalman_detector/utils.py      | 20 ++++++++------------
 2 files changed, 11 insertions(+), 14 deletions(-)

diff --git a/kalman_detector/efficiency.py b/kalman_detector/efficiency.py
index 9bf2b80..98a190a 100644
--- a/kalman_detector/efficiency.py
+++ b/kalman_detector/efficiency.py
@@ -132,9 +132,10 @@ def eff_plot(
 
 if __name__ == "__main__":
     niters = 10000
-
-    template = utils.simulate_gaussian_process(noise_std, corr_len, snr_int, complex_process)
+    nchans = 336
+    corr_len = 300
     freqs = np.arange(0, 335) + 1104
+    template = utils.simulate_gaussian_signal(nchans, corr_len, complex_process=True)
 
     figure = plt.figure(figsize=(5, 5.5), dpi=200)
     grid = figure.add_gridspec(left=0.05, right=0.95, bottom=0.1, top=0.95)
diff --git a/kalman_detector/utils.py b/kalman_detector/utils.py
index 8f7ad87..48b42a4 100644
--- a/kalman_detector/utils.py
+++ b/kalman_detector/utils.py
@@ -111,28 +111,25 @@ def get_snr_from_logsf(logsf: float) -> float:
     return stats.norm.isf(np.exp(logsf))
 
 
-def simulate_gaussian_process(
-    noise_std: np.ndarray, corr_len: float, snr_int: float, complex_process: bool = False
+def simulate_gaussian_signal(
+    nchans: int, corr_len: float, complex_process: bool = False
 ) -> np.ndarray:
     """Simulate 1d Gaussian process.
 
     Parameters
     ----------
-    noise_std : np.ndarray
-        Noise standard deviation.
+    nchans : int
+        Number of frequency channels.
     corr_len : float
-        Correlation length.
-    snr_int : float
-        S/N of the process.
+        Correlation length of the Gaussian process.
     complex_process : bool, optional
         whether to use comlex numbers as the base process, by default False
 
     Returns
     -------
     np.ndarray
-        Simulated array.
+        Normalized mean-subtracted signal array.
     """
-    nchans = len(noise_std)
     rng = np.random.default_rng()
     kernel = np.exp(-np.linspace(-nchans / corr_len, nchans / corr_len, nchans) ** 2)
     kernel /= np.dot(kernel, kernel) ** 0.5
@@ -140,9 +137,8 @@ def simulate_gaussian_process(
     if complex_process:
         base_process += 1.0j * rng.normal(0, 1 / np.sqrt(corr_len), nchans)
     signal = np.abs(np.fft.ifft(np.fft.fft(kernel) * np.fft.fft(base_process)))
-    signal = signal / np.sum(signal) * snr_int * (np.sum(noise_std**2)) ** 0.5
-    noise = rng.normal(0, noise_std, nchans)
-    return signal + noise
+    signal -= np.mean(signal)
+    return signal / np.dot(signal, signal) ** 0.5
 
 
 class SnrResult(object):