Ephemeris is the Satellite Position parameters in space of single Satellite ,the given doc is about extracting an Ephemeris file for all given PRN(pseudo random number of sat) from Matlab SDR (software Defined radio) code for SDR Matlab code :https://github.com/kristianpaul/SoftGNSS and for Data : http://downloads.qi-hardware.com/people/kristianpaul/GNSS_signal_records.tar.gz but the results will be different for different data ,

1. 1
Project Report Template
GNSS Signal Processing, Fall-18
Institute of Space Technology
ASIM KHAN
MS GNSS -7
“Extraction of Ephemeris file from Matlab code”
Introduction:
We catch a file through an RF- front end from GPS Satellites, which is now digitize data,
so in order to find user Position (X, Y, Z), we will process the digitize signal through Acquisition
and Tracking Procedure and then we get binary Data which we called Navigation bits which
usually consists of 1500 bits for each satellite which is encrypted in a frame and the frame is
divided in 5 sub frames
Sub frame 1: Clock Parameters, Space Vehicle health, user range accuracy, issue of Data clock
Sub frame 2&3: Ephemerides
Sub frame 4 & 5: Almanac Data, Space Vehicle health, UTC Data, Ionosphere Models
From step of Acquisition to end all processing is done in Matlab.
Ephemeris is the Satellite keplarian elements etc
Ephemeris Table
M0 Mean Anomaly at Reference Time
∆n Mean Motion Difference From Computed Value
e Eccentricity
√𝐴 Square Root of the Semi-Major Axis
Ω0 Longitude of Ascending Node of Orbit Plane at Weekly Epoch
i0 Inclination Angle at Reference Time

2. 2
ω Argument of Perigee
Ω̇ Rate of Right Ascension
IDOT Rate of Inclination Angle
Cuc Amplitude of the Cosine Harmonic Correction Term to the Argument of Latitude
Cus Amplitude of the Sine Harmonic Correction Term to the Argument of Latitude
Crc Amplitude of the Cosine Harmonic Correction Term to the Orbit Radius
Crs Amplitude of the Sine Harmonic Correction Term to the Orbit Radius
Cic Amplitude of the Cosine Harmonic Correction Term to the Angle of Inclination
Cis Amplitude of the Sine Harmonic Correction Term to the Angle of Inclination
toe Reference Time Ephemeris
IODE Issue of Data (Ephemeris)
Literature review:
1. Simulations of Multiple Spacecraft Maneuvering with MATLAB/Simulink and Satellite
Tool Kit
2. GPS Clock Corrections and Orbit Computations using RINEX 2.11 GPS Navigation
Message Files
3. GNSS Introduction Fobio Dovis
Method:An additional custom code added in Postnavigation .m of GNSS SDR Matlab Code
Line 146 after check number of satellites is above 3.
for loo = 1: numel(eph)
if isempty(eph(loo).e)
else
disp('channel no')
disp(loo)
disp(eph(loo))

3. 3
end
end
clear loo;
Explanation : the loop starts from up to ephemeris(eph)of
different satellites channel .a condition is applied of if
ephemeris and e is a variable in ephemeris chart that is present
in Matlab output .then else displaying channel number and loop
of Ephemeris of each satellite with given PRN number (Pseudo
random number ).and then end.
And the ephemeris of 7 satellites with PRN and channel Number is output Yuma file in
command window of Matlab. Or without adding in Postnavigation.m just run the above code
after Post processing is complete.
Results:In Yuma Format (Ephemeris) of different satellites of Different PRN number and
the channels they came through
channel no
1
IODE_sf2: 178
C_rs: -81
deltan: 4.5045e-09
M_0: 2.9347
C_uc: -4.2096e-06
e: 0.0050
C_us: 7.6666e-06
sqrtA: 5.1537e+03
t_oe: 381600
C_ic: -7.2643e-08
omega_0: -0.0299

4. 4
C_is: -4.2841e-08
i_0: 0.9641
C_rc: 232.5000
omega: 0.4731
omegaDot: -7.9696e-09
IODE_sf3: 178
iDot: -2.6715e-10
weekNumber: 1881
accuracy: 0
health: 0
T_GD: 5.1223e-09
IODC: 11
t_oc: 381600
a_f2: 0
a_f1: 9.0949e-13
a_f0: 1.0263e-05
channel no
3
IODE_sf2: 33
C_rs: 17.8438
deltan: 4.4213e-09
M_0: -0.5920
C_uc: 8.4564e-07

5. 5
e: 2.9964e-04
C_us: 1.0563e-05
sqrtA: 5.1538e+03
t_oe: 381600
C_ic: -5.5879e-09
omega_0: 1.0108
C_is: -5.5879e-09
i_0: 0.9592
C_rc: 173.5625
omega: 2.9466
omegaDot: -7.8928e-09
IODE_sf3: 33
iDot: 1.6858e-10
weekNumber: 1881
accuracy: 0
health: 0
T_GD: 1.8626e-09
IODC: 4
t_oc: 381600
a_f2: 0
a_f1: -4.8885e-12
a_f0: -1.7368e-05
channel no
10

6. 6
IODE_sf2: 65
C_rs: 4.1875
deltan: 4.4873e-09
M_0: 0.8468
C_uc: 3.0547e-07
e: 0.0011
C_us: 1.0315e-05
sqrtA: 5.1537e+03
t_oe: 381600
C_ic: 1.6764e-08
omega_0: 1.0067
C_is: -2.9802e-08
i_0: 0.9595
C_rc: 177.5625
omega: -2.9359
omegaDot: -7.9743e-09
IODE_sf3: 65
iDot: 1.2251e-10
weekNumber: 1881
accuracy: 1
health: 0
T_GD: 2.3283e-09
IODC: 5
t_oc: 381600

7. 7
a_f2: 0
a_f1: -2.0464e-12
a_f0: 4.8256e-05
channel no
14
IODE_sf2: 38
C_rs: 27.6875
deltan: 4.7488e-09
M_0: -1.2603
C_uc: 1.5274e-06
e: 0.0083
C_us: 5.1763e-06
sqrtA: 5.1537e+03
t_oe: 381600
C_ic: 9.8720e-08
omega_0: 2.1344
C_is: 2.1607e-07
i_0: 0.9644
C_rc: 283.3438
omega: -1.9490
omegaDot: -8.2643e-09
IODE_sf3: 38
iDot: -6.4288e-12

8. 8
weekNumber: 1881
accuracy: 0
health: 0
T_GD: -9.3132e-09
IODC: 236
t_oc: 381600
a_f2: 0
a_f1: -2.2737e-12
a_f0: 6.4904e-06
channel no
22
IODE_sf2: 12
C_rs: 10.8438
deltan: 5.2949e-09
M_0: -0.6614
C_uc: 5.1595e-07
e: 0.0076
C_us: 1.0097e-05
sqrtA: 5.1551e+03
t_oe: 381584
C_ic: -8.1956e-08
omega_0: 0.9828
C_is: 1.0990e-07

9. 9
i_0: 0.9228
C_rc: 163.1250
omega: -2.0254
omegaDot: -8.4761e-09
IODE_sf3: 12
iDot: 1.0858e-10
weekNumber: 1881
accuracy: 0
health: 0
T_GD: -1.7695e-08
IODC: 218
t_oc: 381584
a_f2: 0
a_f1: -5.3433e-12
a_f0: 4.0550e-04
channel no
25
IODE_sf2: 46
C_rs: 46.0313
deltan: 3.9116e-09
M_0: 1.2557
C_uc: 2.3227e-06
e: 0.0050

10. 10
C_us: 1.0280e-05
sqrtA: 5.1536e+03
t_oe: 381600
C_ic: -1.3039e-08
omega_0: -2.1302
C_is: 6.5193e-08
i_0: 0.9786
C_rc: 188.5625
omega: 0.6937
omegaDot: -7.8664e-09
IODE_sf3: 46
iDot: 1.4929e-10
weekNumber: 1881
accuracy: 0
health: 0
T_GD: 5.5879e-09
IODC: 12
t_oc: 381600
a_f2: 0
a_f1: -6.4801e-12
a_f0: -1.0712e-04
channel no
31

11. 11
IODE_sf2: 78
C_rs: -26.4063
deltan: 4.1866e-09
M_0: 2.2049
C_uc: -1.2014e-06
e: 0.0083
C_us: 8.0280e-06
sqrtA: 5.1537e+03
t_oe: 381600
C_ic: 1.6764e-08
omega_0: 3.1381
C_is: 5.7742e-08
i_0: 0.9728
C_rc: 231.8125
omega: -0.4432
omegaDot: -7.8293e-09
IODE_sf3: 78
iDot: -4.4073e-10
weekNumber: 1881
accuracy: 0
health: 0
T_GD: -1.3504e-08
IODC: 227
t_oc: 381600
a_f2: 0

12. 12
a_f1: -1.5916e-12
a_f0: 2.8513e-04
Conclusion:As we know Ephemeris file is present in each Satellite signal and we extract
Ephemerides of each Satellite through a Software defined Radio Matlab code for GPS Signals
.which allows us smooth and soft access to satellite position, which can we use for multiple
tasks ,at the time it helps us for finding the user location in X,Y,Z (latitude ,longitude and
height).