source: ntrip/trunk/BNC/todo.txt@ 2627

Last change on this file since 2627 was 2627, checked in by weber, 14 years ago

Consider correct validity of ephemeris sets

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1Todo's sorted by priority:
2
3BNS
4=========================
5(1) One would expect that a new ephemeris set always comes with a later validity
6time tag than a previously distributed ephemeris set. However, this is not always true.
7Sometimes new ephemeris sets come with a validity time tag which is earlier than the
8validity time tag of a previously distributed ephemeris set. This is something
9we should consider in BNS. Gerhard observed that we dont consider this right
10now. The consequence is that a satellite gets lost for PPP clients because
11they deal with another ephemeris set than the correctors provided by
12BNS.
13
14BNC
15=========================
16(1) NMEA GGA string is not fully compatible with the standard.
17The following are observations by Tamas Horvath:
181. Time tag should refer to UTC time and not GPS system time.
192. Time tag format is hhmmss.ss and not hhmmss.
203. The GPS Quality indicator field is 1 (GPS SPS Mode), which is correct, as
21there is no category for PPP. In my opinion the NMEA protocol should be
22extended by a new indicator number for PPP to make a clear difference between
23autonomous GNSS and PPP.
244. The HDOP value is constantly 2.0, which is obviously not real. I think this
25field is filled with 2.0 as a default value in BNC.
265. The Age of Differential GPS data field is not populated. I believe here the
27age of RTCM SSR data should be put.
28
29(2) BNC has a problem when the observation update rate is > 1Hz. Records get
30mixed then in the RINEX files. A 10 Hz stream to test the situation is
31available from GFZ caster 139.17.3.112:4080 through stream A17H.
32
33(3) GW: Keep an eye on www.igs-ip.net/PENC0.
34
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