Changeset 7935 in ntrip for branches


Ignore:
Timestamp:
May 30, 2016, 12:45:50 PM (18 months ago)
Author:
stuerze
Message:

todo list regarding nmea deleted

File:
1 edited

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  • branches/BNC_2.12/src/todo.txt

    r4282 r7935  
    55helps a bit and does not involve too much work? Or should we better do nothing?
    66
    7 (a) Calculate, for each satellite, the STD of the code multipath in the 
     7(a) Calculate, for each satellite, the STD of the code multipath in the
    88iono-free combination Pc, as a combination the carrier phase and the code.
    9 Do this continuously, using a circular register that contains the observations 
     9Do this continuously, using a circular register that contains the observations
    1010of the previous 10 minutes.
    1111(b) Introduce a default STD that is used when, either at the beginning or
     
    1818the phase and to the a priori values of the unknowns. This problem also is true
    1919for (b), (c), and (d). So the fudge factor really depends on the overall strategy
    20 and cannot be used in different software implementations. 
     20and cannot be used in different software implementations.
    2121Everyone has to find it the hard way, by trial and error, making lots of solutions.
    2222(The variance of unit weight is of very limited help for this purpose.)
    23 (d) Downweight the code by a large factor when a satellite is below 20 degrees 
     23(d) Downweight the code by a large factor when a satellite is below 20 degrees
    2424in elevation, or the 3-D precision of the coordinates being estimated falls
    2525below something like 25 cm (again, this will be a different threshold with
    2626different software).
    2727
    28 (2) NMEA GGA string is not fully compatible with the standard.
    29 The following are observations by Tamas Horvath:
    30 (a) Time tag should refer to UTC time and not GPS system time.
    31 (b) Time tag format is hhmmss.ss and not hhmmss.
    32 (c) The GPS Quality indicator field is 1 (GPS SPS Mode), which is correct, as
    33 there is no category for PPP. In my opinion the NMEA protocol should be
    34 extended by a new indicator number for PPP to make a clear difference between
    35 autonomous GNSS and PPP.
    36 (d) The HDOP value is constantly 2.0, which is obviously not real. I think this
    37 field is filled with 2.0 as a default value in BNC.
    38 (e) The Age of Differential GPS data field is not populated. I believe here the
    39 age of RTCM SSR data should be put.
    4028
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