[teqc] Signal/Noise values from Z-Extreme receiver data

Dario Canosa dariocanosa at hotmail.com
Mon Jul 19 23:33:09 MDT 2004


Dear Lou:

I received a large set of TEQC Rinex translated files from receivers ASHTECH-ZXII y Ashtech Z-Extreme.

I found in all files that Rinex files from ASHTECH Z-XII files have "normal" S/N values, but Rinex files from Z-Extreme receivers have inusual low values.

Here is an example:

*** fragment of 0101323a.obs (ASHTECH-Z12) ***

     2.10           OBSERVATION DATA    G (GPS)             RINEX VERSION / TYPE
teqc  2000Feb29                         20031126 18:30:14UTCPGM / RUN BY / DATE
MSWinNT 4.0|PentPro|wcl386 10.6|MSWin95/98/NT|486/DX+       COMMENT
BIT 2 OF LLI FLAGS DATA COLLECTED UNDER A/S CONDITION       COMMENT
0101                                                        MARKER NAME
GAR                 -Unknown-                               OBSERVER / AGENCY
493                 ASHTECH Z-XII3      CD00                REC # / TYPE / VERS
012                 -Unknown-                               ANT # / TYPE
        0.0000        0.0000        0.0000                  APPROX POSITION XYZ
        0.0000        0.0000        0.0000                  ANTENNA: DELTA H/E/N
     1     1                                                WAVELENGTH FACT L1/2
     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
  2003    11    19    16    52   45.0000000     GPS         TIME OF FIRST OBS
                                                            END OF HEADER
03 11 19 16 53 15.0000000  0  6G31G25G 3G20G11G14
    163881.32049    121992.80947  20614307.799    20614316.657    20614307.412

   -135169.76049    -99226.04645  23476649.000    23476663.221    23476649.744

    401236.84149    291232.02346  22088848.354    22088861.183    22088848.818

    -47342.94949    -34561.55546  22833207.043    22833219.599    22833206.840

   -150271.80449   -109618.26847  21851897.708    21851905.008    21851896.847

    352130.13149    241932.75946  22364268.146    22364278.171    22364268.989

 03 11 19 16 53 30.0000000  0  6G31G25G 3G20G11G14
*** end of fragment ****


*** fragment of 0701322b.obs (Z-Extreme) ***
     2.10           OBSERVATION DATA    G (GPS)             RINEX VERSION / TYPE
teqc  2000Feb29                         20031126 18:31:57UTCPGM / RUN BY / DATE
MSWinNT 4.0|PentPro|wcl386 10.6|MSWin95/98/NT|486/DX+       COMMENT
BIT 2 OF LLI FLAGS DATA COLLECTED UNDER A/S CONDITION       COMMENT
0701                                                        MARKER NAME
___                 -Unknown-                               OBSERVER / AGENCY
___                 ASHTECH UZ-12       ZA00                REC # / TYPE / VERS
___                 -Unknown-                               ANT # / TYPE
  2396526.6000 -5206217.2400 -2791238.6500                  APPROX POSITION XYZ
        0.0000        0.0000        0.0000                  ANTENNA: DELTA H/E/N
     1     1                                                WAVELENGTH FACT L1/2
     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
  2003    11    18    13    39    0.0000000     GPS         TIME OF FIRST OBS
                                                            END OF HEADER
03 11 19 16 53 15.0000000  0  8G 1G31G14G11G15G 3G20G25
  -2727568.31443  -2054893.07342  24332321.138    24332341.154    24332321.645
      3716.214        2895.751
 -17569012.83643 -13641080.70642  20508584.291    20508594.406    20508585.718
      -781.902        -609.274
 -14182208.39943 -11007367.76742  22228090.048    22228101.811    22228092.867
     -2591.284       -2019.182
 -16590976.58643 -12893430.70842  21736040.151    21736048.901    21736041.451
      2293.443        1787.098
   -169784.17243    -83278.68442  24298154.772    24298172.032    24298154.260
     -1975.483       -1539.337
 -12586189.95443  -9802697.97242  21980369.384    21980381.242    21980370.239
     -3040.632       -2369.324
 -10854547.65943  -8415804.11442  22732908.967    22732921.839    22732909.781
      1366.384        1064.715
  -8885066.75443  -6887797.97942  23349973.796    23349991.605    23349976.198
      2237.297        1743.348
 03 11 19 16 53 30.0000000  0  8G 1G31G14G11G15G 3G20G25
*** end of fragment ***

I pick for example the same epoch on both files but the same happen in all files (all sites)along one month of measurements.

Seems to be S/N from Z-extreme receivers maps to very low values in (TEQC) Rinex files?.
Is there a way to correct this during translation?
Is that a problem? in TEQC or ASHTECH data?

Thank you.

Dario Canosa.
Geosystems - I.F.T.A.
dariocanosa at hotmail.com



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