def gps_l5(xb_advance, neuman_hoffman):
"""
Generates the GPS L5 code (either I or Q) given the initial state
of the XB shift register and the neuman_hoffman overlay code.
"""
indices = arange(L5_CODE_LENGTH)
xa = xa_code()
xb = xb_code()
sequence = (xa[indices % XA_LENGTH] +
xb[(xb_advance + indices) %
XB_LENGTH]) % 2 # <- initial state used in index
nh = Code(neuman_hoffman, NEUMAN_HOFFMAN_RATE)
code = Code(sequence, L5_CODE_RATE)
new_length = L5_CODE_LENGTH * len(nh.sequence)
return Code.overlay(code, nh)
def gps_l2_cl(initial_state):
"""
Generates the L2 CL code given the initial shift register state.
"""
state = initial_state
sequence = zeros((CL_LENGTH, ))
for i in range(CL_LENGTH):
state = shift_state(state)
sequence[i] = state & 0x1
return Code(sequence, 511500)
def gps_l5(xb_advance, neuman_hoffman):
"""
Generates the GPS L5 code (either I or Q) given the initial state
of the XB shift register and the neuman_hoffman overlay code.
"""
indices = arange(L5_CODE_LENGTH)
xa = xa_code()
xb = xb_code()
sequence = (xa[indices % XA_LENGTH] + xb[(xb_advance + indices) % XB_LENGTH]) % 2 # <- initial state used in index
nh = Code(neuman_hoffman, NEUMAN_HOFFMAN_RATE)
code = Code(sequence, L5_CODE_RATE)
new_length = L5_CODE_LENGTH * len(nh.sequence)
return Code.overlay(code, nh)
def gps_l1ca(svid):
"""Generates GPS L1 CA PRN code for given SV id.
Parameters
----------
sv_id : int
the id of the satellite for which the
Returns
-------
output : ndarray of shape(1023,)
the complete code sequence
Notes
-----
"""
ps = L1_CODE_PHASE_ASSIGNMENTS[svid].ca_phase_select
g1 = gold_code([2, 9], [9])
g2 = gold_code([1, 2, 5, 7, 8, 9], [ps[0] - 1, ps[1] - 1])
return Code((g1 + g2) % 2, CODE_RATE)
def gps_l2c(svid):
phase_assignment = L2_CODE_PHASE_ASSIGNMENTS[svid]
cm = gps_l2_cm(phase_assignment.cm_initial_state)
cl = gps_l2_cl(phase_assignment.cl_initial_state)
return Code.time_multiplex(cm, cl)
def gps_l2c(svid):
phase_assignment = L2_CODE_PHASE_ASSIGNMENTS[svid]
cm = gps_l2_cm(phase_assignment.cm_initial_state)
cl = gps_l2_cl(phase_assignment.cl_initial_state)
return Code.time_multiplex(cm, cl)
