I implemented data decoding routines.
I also started using the gpstk libraries.
After 5 subframes I was able to generate the following ephemeris information using the gpstk libraries.
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Broadcast Ephemeris (Engineering Units)
PRN : 20
Week(10bt) SOW DOW UTD SOD MM/DD/YYYY HH:MM:SS
Clock Epoch: 499( 499) 439200 Fri-5 216 7200 08/04/1989 02:00:00
Eph Epoch: 499( 499) 439200 Fri-5 216 7200 08/04/1989 02:00:00
Transmit Week: 499
Fit interval flag : 0
SUBFRAME OVERHEAD
SOW DOW:HH:MM:SS IOD ALERT A-S
SF1 HOW: 438996 Fri-5:01:56:36 0x044 0 on
SF2 HOW: 439002 Fri-5:01:56:42 0x44 0 on
SF3 HOW: 439008 Fri-5:01:56:48 0x44 0 on
CLOCK
Bias T0: 8.76886770E-005 sec
Drift: 9.09494702E-013 sec/sec
Drift rate: -2.77555756E-017 sec/(sec**2)
Group delay: -6.51925802E-009 sec
ORBIT PARAMETERS
Semi-major axis: 3.03834575E+003 m**.5
Motion correction: 4.86377402E-009 rad/sec
Eccentricity: 4.95970747E-001
Arg of perigee: 1.34752371E+000 rad
Mean anomaly at epoch: 1.32153453E+000 rad
Right ascension: 1.87509305E+000 rad 8.24248619E-009 rad/sec
Inclination: -9.42658741E-001 rad -1.47148986E-010 rad/sec
HARMONIC CORRECTIONS
Radial Sine: 3.16250000E+001 m Cosine: 2.24062500E+002 m
Inclination Sine: 2.42143869E-008 rad Cosine: -6.33299351E-008 rad
In-track Sine: -7.47293234E-006 rad Cosine: -1.65589154E-006 rad
SV STATUS
Health bits: 0x00 URA index: 0
Code on L2: P only L2 P Nav data: off