todo

gps 软件接收机,用 c++ 语言实现

Review use of T_GD

problem with signal going below threshold losing C/A sync

try loading signal data as s16 all the way into the correlator 
functions to see if this helps with bandwidth issues, 
this will require s16->f32 conversion (sse?) at corr Func .

also try s16 for cos/sin + s8 for spreading code? 

Display Lat, Long for user position

Decode Subframes 4 + 5
  Update PRNS for atomosphere
  ...

Assembly / Intrinsic Correlators

TOW roll over mitigation in subframe/word syncronization
  TOW for subframe is (msg.TOW + MAX_TOW - 1) % MAX_TOW  

Kalmen filter 
  
Real Data Processing:
  PLL + DLL
  AGC
  Figure how to calculate corrilation threshold for real data
    possible keep two sums one of correlator the other of abs(signal)
  Real Hardware/Data
  
Altivec Correlator


DONE:
Replace library code with my own code for least squares routines / matrix inversion
Generates test data from Frames I got from Garmin GPS (Upconversion + Spreading)
Downconverstion, Despreading, Search & Tracking
Decode Subframes 1,2,3
Samples the correlators every second
Attempts to Calculate User position
Get orbits to work