[teqc] Does SNV message must be the 1st record at the beginning of raw data file

Jerry Leo jerry_leo at msn.com
Wed Feb 22 08:06:52 MST 2006


Hi,

My PC is connected to GPS recevier directly. On a FC 3 box,  I made a
PERL script to log the real time output from the ASHTECH Z-Surveyor
receiver in 1-hour segments. I have enabled the output of raw data
messages CBEN, DBEN, MBN, PBN and SNV.  Except the first 1-hour
segments,  C1, D1 and D2  code are missing after the 1-hour segments is
translated to RINEX file using TEQC,  only there are L1, L2, P1 and P2
four observation types.

For example, Logging script launches at 03:10,  the first 1-hour segments
will be created at 04:00,  it has L1, L2, C1, P1, P2, D1 and D2 seven
observation types after translating to RINEX format using TEQC. The
second 1-hour segments will be created at 05:00,  but it only has L1, L2,
P1 and P2 four observation types after translating to RINEX format using
TEQC, C1, D1 and D2 code are missing.  In the header section, there is a
comment "note: cannot distinguish between L1(CA)=C1 and L1(P1)=P1".
And same to  the next 1-hour segments.

I checked all of the raw data files and found that the 1st records at the
beginning of the raw data file wasn't SNV message except the 1st 1-hour
segments. So I made a test, edited one of the raw data files and removed
records before SNV message at the begin of the file. Now there is no a
comment "note: cannot distinguish between L1(CA)=C1 and L1(P1)=P1"
in the header. But I found another thing.  In the O-file, only the 1st 
section
has seven observation types, for the other secionts, there are only four
observation types.

I'd like to make real-time estimation of atmospheric water vapor. So I have
several questons,

1.  What's the side effect for me if the 1st record at the beginning of raw
data file isn't SNV messages?
2.  What's the meaning for "cannot distinguish between L1(CA)=C1 and
L1(P1)=P1"?
3.  Should I have to make sure that the 1st record at the beginning of raw
data file must be SNV message?
4.  Why only the 1st section has seven observation types and the other
sections only have four observation types in the O-file?

Here are the examples of output

***Without removing records before SNV message at the begin of the file***

     4    L1    L2    P1    P2                              # / TYPES OF 
OBSERV
pseudorange smoothing corrections applied                   COMMENT
note: cannot distinguish between L1(CA)=C1 and L1(P1)=P1    COMMENT
  2006     2     9     5     0    0.0000000     GPS         TIME OF FIRST 
OBS
                                                            END OF HEADER
06  2  9  5  0  0.0000000  0  8G 2G 4G 7G 9G17G20G24G28
-14074617.092   -10957346.555    22115608.623    22115609.582
-17245640.134   -13393620.998    20628209.957    20628212.476
  -7390880.399    -5753189.011    23264276.796    23264280.903
    369532.666      353662.009    24305556.373    24305560.391
  -7883030.249    -6111737.607    21617091.479    21617093.518
   6144721.569     4810102.073    24836279.921    24836282.799
  -4825223.234    -3720398.506    22302789.230    22302792.168
  -4762025.777    -3693852.186    21996290.115    21996292.783
06  2  9  5  0 30.0000000  0  8G24G17G 7G 4G20G 2G28G 9
  -4731289.12943  -3647203.13442  22020871.5104   22020874.8984
  -7851435.99943  -6087118.73942  21323311.4304   21323313.1974
  -7429922.28243  -5783611.24942  22957054.2264   22957057.9414
-17215560.83643 -13370182.60142  20334141.5914   20334143.9464
   6251452.37943   4893268.88942  24556797.1694   24556800.7914
-14106598.10643 -10982266.81042  21809730.1454   21809731.1284
  -4661263.89643  -3615336.50342  21715671.8804   21715674.4244
    406916.57543    382792.23542  24012878.0344   24012882.1204


*** After removing records before SNV message at the begin of the file***

      7    L1    L2    C1    P2    P1    D1    D2            # / TYPES OF 
OBSERV
SNR is mapped to RINEX snr flag value [1-9]                COMMENT
  L1: 1 -> 1;  90 -> 5; 210 -> 9                            COMMENT
  L2: 1 -> 1; 150 -> 5; 250 -> 9                            COMMENT
pseudorange smoothing corrections applied                   COMMENT
  2006     2     9     5     0   30.0000000     GPS         TIME OF FIRST 
OBS
                                                            END OF HEADER
06  2  9  5  0 30.0000000  0  8G24G17G 7G 4G20G 2G28G 9
  -4731289.12943  -3647203.13442  22020871.0174   22020874.8984   
22020871.5104
     -3133.5194      -2441.7144
  -7851435.99943  -6087118.73942  21323310.5114   21323313.1974   
21323311.4304
     -1056.4644       -823.2214
  -7429922.28243  -5783611.24942  22957053.8614   22957057.9414   
22957054.2264
      1301.1684       1013.8944
-17215560.83643 -13370182.60142  20334140.5014   20334143.9464   
20334141.5914
     -1009.5124       -786.6294
   6251452.37943   4893268.88942  24556796.5634   24556800.7914   
24556797.1694
     -3563.3564      -2776.6454
-14106598.10643 -10982266.81042  21809729.5924   21809731.1284   
21809730.1454
      1059.9954        825.9654
  -4661263.89643  -3615336.50342  21715671.4504   21715674.4244   
21715671.8804
     -3365.8854      -2622.7584
    406916.57543    382792.23542  24012877.1464   24012882.1204   
24012878.0344
     -1254.1364       -977.2544
06  2  9  5  0 30.0000000  0  8G 2G 4G 7G 9G17G20G24G28
-14106598.128   -10982266.810    21809730.198    21809731.097
-17215560.862   -13370182.600    20334141.617    20334143.955
  -7429922.302    -5783611.249    22957052.393    22957057.760
    406916.547      382792.235    24012878.200    24012882.967
  -7851436.016    -6087118.739    21323311.479    21323313.038
   6251452.353     4893268.889    24556797.233    24556799.811
  -4731289.148    -3647203.133    22020871.538    22020874.806
  -4661263.918    -3615336.503    21715671.903    21715674.691

Thanks

Jerry




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