[teqc] Fw: Convert ASHTECH stream. Probably a teqc bug???

[Lou Estey]

Ambrogio,

Probably not.

> I've found a problem with Magellan DG14 data stream.
> In this case the stream has the same format of Ashtech receivers.
> To convert rs232 Ashtech (Magelan DG14) stream (enclosed in zip form) 
> I've used:
> teqc -ash s -O.obs "C1L1D1" -week 1466 192.log >dg14.08o
> with this results (I've write only one epoch):
> 
> Using TEQC:
> 08  2 14 17 10 10.0000000  0  9G20G13G 4G17G16G23G25G 2G27
>   22242565.262     6006513.006 8     -3674.487
>   20213804.250    -7364454.506 9      -543.415
>   21038906.673    -7242284.635 9      -696.259
>   25058511.328     9261516.989 7     -4254.321
>   25193237.105     -259091.820 9       702.769
>   21014005.494     2546025.121 9     -3014.025
>   21636816.311   -10063223.286 9      1415.354
>   22843592.692   -14520539.353 9      1766.539
>   23068457.424    -9009999.301 9      2022.916
> 
> Using Novatel Grafnav utility: (the free software version works not in 
> rinex format but in ascii format)
> 
> P: 17:10:10.00 02/14/2008 45.33151870 8.42194371 181.789
> T: 407410.000 1466 09 0.3
> M: 20 CA 22242565.262 L1 -6006513.006 D1 -3674.488 LK1  255.0
> M: 13 CA 20213804.250 L1  7364454.506 D1  -543.415 LK1  255.0
> M: 04 CA 21038906.673 L1  7242284.635 D1  -696.260 LK1  255.0
> M: 17 CA 25058511.328 L1 -9261516.989 D1 -4254.321 LK1    3.0
> M: 16 CA 25193237.105 L1   259091.820 D1   702.769 LK1  255.0
> M: 23 CA 21014005.494 L1 -2546025.121 D1 -3014.025 LK1  255.0
> M: 25 CA 21636816.311 L1 10063223.286 D1  1415.354 LK1  255.0
> M: 02 CA 22843592.692 L1 14520539.353 D1  1766.539 LK1  255.0
> M: 27 CA 23068457.424 L1  9009999.301 D1  2022.916 LK1  255.0
>  
> As you can see the SIGN of phases are all changed.
> The problem is that with Novatel conversion the results are logic and 
> correct, but not with teqc phases.

To check the sign of the RINEX phase values, you need to look at
the code pseudorange values and phase values for at least one SV
over at least two epochs, e.g. for GPS PRN#20 (from teqc):

  08  2 14 17 10 10.0000000  0  9G20G13G 4G17G16G23G25G 2G27
   22242565.262     6006513.006 8     -3674.487
...
  08  2 14 17 10 15.0000000  0  9G20G13G 4G17G16G23G25G 2G27
   22246061.393     6024887.124 8     -3675.748
...
  08  2 14 17 10 20.0000000  0  9G20G13G 4G17G16G23G25G 2G27
   22249559.599     6043267.159 8     -3677.031

We see that the code pseudorange _and_ phase are increasing
over these three epochs -- which is self-consistent.

If we reversed the sign of the phase, as in the Grafnav utility
data dump, then the code pseudorange would be increasing and the
phase would be decreasing -- which is not self-consistent.

So I think teqc is doing the RINEX translation AOK.

--lou

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Louis H. Estey, Ph.D.              office:  [+001] 303-381-7456
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    WWW:  http://www.unavco.org   http://jules.unavco.org

"If the universe is the answer, what is the question?"
                                                -- Leon Lederman
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