NavCom Rinex Utility Rev.D - Manual (Page 14)

RINEX Utility – Rev D
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
RINEX Utility conforms to RINEX Standard 2.10, which states that the Cartesian
ECEF position in the observation file header is WGS84. This means that the height
entered in the RINEX Utility must be WGS84. The RINEX Utility makes no attempt
to convert other datum heights to WGS84. Using height data from a datum other
than WGS84 will result in errors in the Z-axis.

Output start time / Output end time: If enabled, the Output Start and Output End times allow
the user to parse a large raw data file into a smaller snap shot of the overall data collection
period. Caveats are that the GPS Week Number, and the GPS Time Of Week (TOW in
seconds) be entered. If the Output Start and Output End times are disabled, the RINEX
Utility will process the entire data collection period. If the Output Start time is set to be after
the Output End time, no processing will occur. The obverse is true for the Output end time
box.

Refer to the sections below, GPS Week Number and GPS Time, for details on
these values.
GPS Week Number
The GPS Week Number count began at midnight on the evening of 05 January 1980 / morning
of 06 January 1980. Since that time, the count has been incremented by 1 each week, and
broadcast as part of the GPS message. The GPS Week Number field in the data stream is
modulo 1024. This meant that at the completion of week 1023, the GPS Week Number rolled
over to 0 on midnight GPS Time of the evening of 21 August 1999 / morning of 22 August 1999.
The NCT-2000D and NCT-2100D use an adjusted 16-bit integer (U16) in the data to avoid this
confusion. They can handle up to week 65535.
For example, in Figure 5 the GPS Week Number for the Output Start / End times is 1313. To
determine the week/date, subtract 1024 from 1313, which is 290. Then add 290 weeks to 21
August 1999. The result is Sunday 6 March 2005.
GPS Time
The GPS time (seconds into the week) always starts on Sunday morning at 00:00 GMT. Each
24 hour period contains 86,400 seconds. A full week contains 604,800 seconds. Please see the
table below for a breakdown of hourly / daily increments.