"""
:file: signals.py
:author: Zhu Dengda (zhudengda@mail.iggcas.ac.cn)
:date: 2024-07-24
该文件包括一些常见的时间信号，最高幅值均为1
"""
import numpy as np
import numpy.ctypeslib as npct
from ctypes import byref, cast
from .c_interfaces import *
__all__ = [
"gen_triangle_wave",
"gen_parabola_wave",
"gen_trap_wave",
"gen_ricker_wave",
]
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def gen_triangle_wave(vlen, dt):
'''
generate triangle-shape wave
:param vlen: signal length (s)
:param dt: time interval (s)
:return:
- **wave** - amplitude sequence
'''
return gen_trap_wave(vlen/2.0, vlen/2.0, vlen, dt)
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def gen_parabola_wave(vlen, dt):
'''
generate parabola-shape wave
:param vlen: signal length (s)
:param dt: time interval (s)
:return:
- **wave** - amplitude sequence
'''
ct1 = c_float(vlen)
cnt = c_int(0)
carr = C_grt_get_parabola_wave(dt, byref(ct1), byref(cnt))
arr = npct.as_array(carr, shape=(cnt.value,)).copy()
C_grt_free(carr)
return arr
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def gen_trap_wave(t1, t2, t3, dt):
'''
generate trapezoid-shape wave
:param t1: ramp-up cutoff time (s)
:param t2: plateau cutoff time (s)
:param t3: ramp-down cutoff time (s)
:param dt: time interval (s)
:return:
- **wave** - amplitude sequence
'''
ct1 = c_float(t1)
ct2 = c_float(t2)
ct3 = c_float(t3)
cnt = c_int(0)
carr = C_grt_get_trap_wave(dt, byref(ct1), byref(ct2), byref(ct3), byref(cnt))
arr = npct.as_array(carr, shape=(cnt.value,)).copy()
C_grt_free(carr)
return arr
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def gen_ricker_wave(f0:float, dt:float):
'''
generate Ricker wavelet
:param f0: center frequency (Hz)
:param dt: time interval (s)
:return:
- **wave** - amplitude sequence
'''
cnt = c_int(0)
carr = C_grt_get_ricker_wave(dt, f0, byref(cnt))
if cast(carr, c_void_p).value is None:
raise ValueError("NULL pointer")
arr = npct.as_array(carr, shape=(cnt.value,)).copy()
C_grt_free(carr)
return arr