improve jitter generation

wave_gen: change to gussian jitter distribution
wrapper: reduce gtx_jitter to meet real world performance
docs: remove noise limitation

README.md

@@ -54,4 +54,3 @@ nix develop
 </details><br>
 
 ## Limitation
-1. The white noise is used to simulate jitter which may result in higher phase noise

src/wrpll_simulation/wave_gen.py

@@ -3,8 +3,9 @@ import numba as nb
 from numba import njit
 
 
-def white_noise(low, high, size, seed=None):
-    return np.random.default_rng(seed).uniform(low, high, size)
+
+def gussian_jitter(RMS_jitter, size, seed=None):
+    return np.random.default_rng(seed).normal(0, RMS_jitter/2, size)
 
 
 @njit(fastmath=True)

src/wrpll_simulation/wrpll.py

@@ -1,6 +1,6 @@
 import numpy as np
 from wrpll_simulation.sim import simulation_jit
-from wrpll_simulation.wave_gen import white_noise
+from wrpll_simulation.wave_gen import gussian_jitter
 
 
 class WRPLL_simulator():
@@ -17,7 +17,7 @@ class WRPLL_simulator():
         start_up_delay,
         i2c_comm_delay=85.6e-6,
         dcxo_settling_delay=100e-6,
-        gtx_jitter=370e-15,
+        gtx_jitter=200e-15,
         dcxo_freq=125_000_000,
         dcxo_jitter=95e-15,
         freq_acquisition_error=100,
@@ -38,11 +38,11 @@ class WRPLL_simulator():
 
         # init condition
         self.gtx_freq = gtx_freq
-        self.gtx_jitter = white_noise(-gtx_jitter, gtx_jitter, len(self.time), seed)
+        self.gtx_jitter = gussian_jitter(gtx_jitter, len(self.time), seed)
 
         self.dcxo_freq = dcxo_freq
-        self.h_jitter = white_noise(-dcxo_jitter, dcxo_jitter, len(self.time), seed)
-        self.m_jitter = white_noise(-dcxo_jitter, dcxo_jitter, len(self.time), seed)
+        self.h_jitter = gussian_jitter(dcxo_jitter, len(self.time), seed)
+        self.m_jitter = gussian_jitter(dcxo_jitter, len(self.time), seed)
         self.N = N
         self.helper_init_freq = helper_init_freq