def calc(self, x, n=5):
f = lambda fd: array(
[e**(-2j * pi * fd * n / self.fs) for n in arange(self.N)])
# Filters.
a = [1.0]
b_coarse = signal.firwin(60, 20e3 / self.fs)
b_medium = signal.firwin(60, 1e3 / self.fs)
b_fine = signal.firwin(60, 0.4e3 / self.fs)
# Truncate and reshape input signal.
x = reshape(self.truncate(x, self.N), (-1, self.N))[:n]
# Coarse acquisition.
# Hvorfor virker conj(fft.fft naar fft.ifft ikke funker??
X = conj(fft.fft(x))
r = sum(array([abs(fft.ifft(self.LC * X_i)) for X_i in X]), axis=0)
(f_coarse, ca_delay) = self.argmax_2d(r)
f_coarse = self.doppler_range[f_coarse]
p_debug("Coarse f: %f Hz." % (f_coarse))
# Remove C/A code from input signal.
x = x * ca_code.ca_code(svn=self.svn, fs=self.fs, ca_shift=ca_delay)
# Mix down to f_coarse and reduce BW to 1kHz.
x = x * f(f_coarse)
x = signal.lfilter(b_coarse, a, x)
# Medium resolution calculation.
f_medium = arange(-400, 400 + 1, 400)
Xk = [abs(self.dft(x[0], f_i)) for f_i in f_medium]
f_medium = f_medium[argmax(Xk)]
if x.ndim < 2:
x = reshape(x, (1, -1))
p_debug("Medium f: %f Hz." % f_medium)
# Mix down to f_medium and reduce BW to 400 Hz.
x = x * f(f_medium)
x = signal.lfilter(b_medium, a, x)
# Fine frequency calculation.
Xk = self.dft(x, f_medium)
theta = angle(Xk)
d_theta = array(
[theta[n] - theta[n - 1] for n in range(1, len(theta))])
def foo_theta(d_theta):
tmp = d_theta
if abs(d_theta) > self.threshold:
d_theta = tmp - 2 * pi
if abs(d_theta) > self.threshold:
d_theta = tmp + 2 * pi
if abs(d_theta) > self.threshold:
d_theta = tmp - pi
if abs(d_theta) > self.threshold:
d_theta = tmp - 3 * pi
if abs(d_theta) > self.threshold:
d_theta = tmp + pi
return d_theta
d_theta = array(map(foo_theta, d_theta))
f_fine = d_theta.mean() / (2 * pi * 1e-3)
p_debug("Fine frequency: %f Hz." % f_fine)
return (f_coarse + f_medium + f_fine, ca_delay)
def calc(self, x, n=5):
f = lambda fd: array([ e**( -2j*pi*fd*n/self.fs) for n in arange(self.N)])
# Filters.
a = [1.0]
b_coarse = signal.firwin( 60, 20e3/self.fs)
b_medium = signal.firwin( 60, 1e3/self.fs)
b_fine = signal.firwin( 60, 0.4e3/self.fs)
# Truncate and reshape input signal.
x = reshape ( self.truncate( x, self.N), (-1, self.N))[:n]
# Coarse acquisition.
# Hvorfor virker conj(fft.fft naar fft.ifft ikke funker??
X = conj(fft.fft(x))
r = sum( array([ abs(fft.ifft( self.LC*X_i)) for X_i in X ]), axis=0)
(f_coarse, ca_delay) = self.argmax_2d(r)
f_coarse = self.doppler_range[ f_coarse ]
p_debug( "Coarse f: %f Hz." % (f_coarse) )
# Remove C/A code from input signal.
x = x * ca_code.ca_code(svn=self.svn, fs=self.fs, ca_shift=ca_delay)
# Mix down to f_coarse and reduce BW to 1kHz.
x = x * f(f_coarse)
x = signal.lfilter( b_coarse, a, x )
# Medium resolution calculation.
f_medium = arange(-400, 400+1, 400)
Xk = [ abs(self.dft(x[0],f_i)) for f_i in f_medium ]
f_medium = f_medium[ argmax(Xk) ]
if x.ndim < 2:
x = reshape(x, (1,-1))
p_debug( "Medium f: %f Hz." % f_medium )
# Mix down to f_medium and reduce BW to 400 Hz.
x = x * f(f_medium)
x = signal.lfilter( b_medium, a, x )
# Fine frequency calculation.
Xk = self.dft(x, f_medium)
theta = angle(Xk)
d_theta = array([ theta[n] - theta[n-1] for n in range(1, len(theta)) ])
def foo_theta(d_theta):
tmp = d_theta
if abs(d_theta) > self.threshold:
d_theta = tmp - 2*pi
if abs(d_theta) > self.threshold:
d_theta = tmp + 2*pi
if abs(d_theta) > self.threshold:
d_theta = tmp - pi
if abs(d_theta) > self.threshold:
d_theta = tmp - 3*pi
if abs(d_theta) > self.threshold:
d_theta = tmp + pi
return d_theta
d_theta = array( map( foo_theta, d_theta))
f_fine = d_theta.mean()/(2*pi*1e-3)
p_debug( "Fine frequency: %f Hz." % f_fine )
return (f_coarse + f_medium + f_fine, ca_delay)
def local_code(self, shift=0):
code = ca_code.ca_code(svn=self.svn, fs=self.fs, ca_shift=shift)
f = lambda fd: array(
[e**(2j * pi * fd * n / self.fs) for n in range(len(code))])
lc = array([code * f(fd) for fd in self.doppler_range])
return (lc, fft.fft(lc))
def local_code(self, shift=0):
code = ca_code.ca_code(svn=self.svn, fs=self.fs, ca_shift=shift)
f = lambda fd: array( [ e**(2j*pi*fd*n/self.fs) for n in range(len(code))] )
lc = array( [code*f(fd) for fd in self.doppler_range ] )
return ( lc, fft.fft(lc))
