[time-nuts] new gps sat prn30 svn64

[tom jones]

Hi Skip,

Your message 30,30 is nearly identical to mine on 3-2-14 2:00mst

I just realized I been putting my time stamps as pdt should be pst (pacific standard time).

Anyway the supperb time rate from svn64 prn30 changed from execellant to average. Compareable to the other sats on
2/26/2014 01:34:33 pst here is my data.

3.8706945954e-010,-2.7224445300e-014	02/25/2014 14:25:20
3.8088047897e-010,-2.8666966126e-014	02/25/2014 14:28:50
3.8088047897e-010,-2.8666966126e-014	02/25/2014 14:28:50
3.7882484806e-010,-3.0106044610e-014	02/25/2014 14:30:20
3.7575403151e-010,-3.0106044610e-014	02/25/2014 14:31:50

-7.6402494734e-007,3.6402148657e-012	02/26/2014 01:34:33
-7.6389389961e-007,3.6402148657e-012	02/26/2014 01:35:33
-7.6336994898e-007,3.6386020065e-012	02/26/2014 01:37:33

I'm at somewhat of a loss to explain this change in clock rate (stability).
Perhaps the military signal is derived from the better clock ?
and the civilians get a less stable clock rate/signal ? 

I haven't rulled out dopplar shift or my mis-understanding of how gps works and what msg 30 really means.
Perhaps the sat is broadcasting the bias and drift every minute and the gps receiver is dummer than I thought ?

Here is my data from the approximate time as your data.

GeoNav PC Time=1393793993 03/02/2014 12:59:53
30,30,7.55669999999e+004,-1.0512244642e+007,-2.0403662041e+007,1.3915637457e+007,1.4887479321e+003,8.9976062727e+002,2.4431245733e+003,1.3331348485e-006,3.6930953087e-012,4,4.0960000000e+005,1.0816000000e+004,1.5091755390e+000

I would have thought our messages would be more exact to each other as I've run two receivers from my location running sirf twice on the same pc with both sirf III and sirf IV receivers simotainiously logging and the comparied messages are within 2 or 3 least significant digits of each other..

PRobably are location differences are the reason for a less equal comparison.

sunday 3-2-14 the sat passed nearly overhead at my location which would have presented  the maximum dopplar shift.
but that wouldn't explain the dramitic shift in the clock stability seen on 2-26-14.

I will be logging the data daily hoping to see the prn30 clock go back to the better stability.

I put and sd card in my laptop pc and now run sirfdemo from the sd card and log to that sd card. I feel it puts less where on my harddrive..

I can easily see prn30 orbit moving westwardly each day across the sat mapping screen. very cool !!

I also have written a program to parse out the clock bias and drift. here is its output.

prn clk bias	clk drift	30sec drift   30sec clk bias  next orbit clk bias update & utc
01 5.419324e-07 1.939370e-1213 1.350894e-14  2.4980e-10 0714  3.056667e-08 0316
02 4.801467e-04 -6.812491e-13  -2.547918e-14 -7.5000e-12 1332 1.832122e-07 0619
03 3.292035e-04 -7.611533e-14  1.553618e-14  -2.2900e-12 1529 -1.075634e-07 150
14 5.685252e-06 -6.154375e-13  2.511121e-14  -8.2501e-12 1112 5.062425e-08 0459
05 -3.874342e-04 2.121078e-123 8.206977e-15  9.7660e-11 1433  3.457315e-08 0838
06 2.857013e-04 1.634064e-11   5.935703e-14  4.9022e-10 1529  6.195851e-07 1344
07 3.165876e-04 1.958476e-12   5.030264e-15  7.9590e-11 0610  -5.385762e-07 222
08 1.200872e-05 -4.117289e-12  1.142446e-14  -3.7056e-11 0723 -3.790054e-07 234
09 3.072839e-04 5.659474e-125  3.575135e-14  8.4890e-11 0728  3.072825e-04 0025
10 -1.154085e-04 -3.748887e-12 2.945560e-14  -4.8740e-11 1212 -1.017679e-08 075
11 -4.664052e-04 -7.469855e-12 1.838373e-14  -1.1952e-10 0611 -1.192491e-08 021
12 1.880373e-04 3.790502e-12   -6.092783e-15 9.0580e-11 1316  1.010878e-07 0640
13 2.713727e-05 -3.561521e-12  1.282676e-14  -6.0546e-11 0424 2.726619e-05 2116
14 1.961350e-04 -3.153479e-12  1.802226e-14  -9.4600e-11 1529 -2.227599e-07 144
15 -1.645517e-04 -3.145682e-12 1.313034e-14  -7.8620e-11 1529 -1.402962e-08 113
16 -2.304940e-04 3.668937e-125 9.299852e-15  1.0947e-10 1529  5.328928e-08 1304
17 -7.047949e-05 -4.629986e-12 -2.057078e-14 -3.1959e-10 1008 -7.042604e-05 030
18 3.034303e-04 7.149177e-123  -5.420144e-15 2.1093e-10 1529  7.296043e-08 1140
19 -4.404313e-04 -2.519745e-12 1.712601e-13  -9.5182e-10 0445 -1.502963e-08 235
20 1.639282e-04 3.410605e-12   -1.746089e-12 2.3873e-09 0822  8.219745e-08 0635
21 -3.453992e-04 4.039002e-134 -4.799720e-14 1.0840e-11 1529  -1.898633e-07 102
22 2.150482e-04 4.723546e-12   6.304853e-15  1.4105e-10 1529  1.237934e-07 1302
23 1.918922e-06 -6.003539e-12  4.613150e-14  -6.0035e-12 0306 2.001197e-06 1931
24 -2.378059e-05 -1.316009e-12 -5.128276e-16 -3.9554e-11 1529 1.192998e-08 1507
25 1.573178e-05 2.737902e-122  -1.925977e-15 5.2020e-11 1416  6.875391e-08 0820
26 1.577180e-04 -1.734294e-11  2.159037e-14  -4.5705e-10 1521 -7.768384e-08 112
27 -1.932695e-05 -8.357383e-13 1.904347e-15  -2.5027e-11 1529 -3.765017e-08 140
28 3.344866e-04 -3.703717e-13  -8.318476e-14 -3.8030e-11 0842 3.343273e-04 0104
29 5.130142e-04 3.020466e-12   -4.085924e-15 9.0540e-11 1529  1.704589e-07 0854
30 -1.273339e-10 -6.295711e-14 8.385220e-16  -1.7857e-11 1044 -6.734891e-04 073
31 3.334261e-04 2.777229e-125  -2.872355e-14 5.2549e-10 1226  -3.812314e-07 180
32 -4.815533e-04 8.795522e-12  -2.272228e-14 2.6264e-10 0021  -1.415768e-06 174

msg36 1780 574194000 02 22 2014
  15:29:38000 
 76137 78585 000 06304 cli00 hed00
 hpe529 vpe081 ck 1451592983 dft 1832528
 cder0 dist0 derr0 hder0 sats9 hdop4  dop0



how long have you been using sirfdemo program?