[teqc] helpful tip of week 2038

Lou Estey lou at unavco.org
Thu Jan 31 09:54:36 MST 2019

This week's tip: qc: 'Freq. no. and timecode' line

Occasionally I'm asked about this particular qc line, which for a standard 24-hour reference site
data file might look like:

Freq no. and timecode : 2 14269 ffffff

This qc line was added back in Apr 2006 for a purpose described below for an on-line tool
developed by UNAVCO, but anyone can take advantage of the information in this line.

The first number was a simple attempt back in 2006 to have some sort of index to account
for the tracking capability of the receiver based on what was being found in the data file:

1 = single-frequency receiver, probably GPS L1C/A, SBAS L1C/A, and/or GLONASS G1SA
2 = dual-frequency receiver, probably legacy signals: L1/L2 for GPS, L1 for SBAS, and G1/G2 for GLONASS
3 = triple-frequency receiver, probably tracking GPS and/or SBAS L5
4 or higher = a more complex GNSS tracking capability than any of the above

The second number is the count of days since 6.0 Jan 1980 (the beginning of GPS time) of
the first data epoch in the data, where 6 Jan 1980 is equivalent to day 0 (zero).
Day 14269 is 30 Jan 2019.

The third and any other following fields are hexadecimal representations for the hours 0 - 23,
the third field being for the specified GPS day, and then, if any additional fields, sequentially
incremented day by day after that. (A full day with no data would be represented as '000000').
Therefore each hexadecimal number (0-9,a-f) is for 4 hours. The representation for each day
is big-endian; thus the bits for hours for 0-3 are in the hexadecimal number furthest to the
right in each field (i.e. the least-significant number of each field), the bits for hours 4-7
are in the next hexadecimal number to the left, and so on. Furthermore, a bit is set for an
hour if there are one or more epochs of data for that hour, i.e. a bit set for an hour means
there is at least some data during that hour and it does not mean the data for the hour is complete.

These fields are read by our archiving software to populate what we call "timecode" files,
which are binary, and then the information in these files are what are used in the UNAVCO
GPS/GNSS Data Archive Interface (DAI) to show for which days there are data for various sites.
For example, for P197, including all possible sampling rates for which data was collected
can be seen here:


(The reason for the two 1-Hz entries relates to the way the data is collected: the top
entry represents data downloads of 1-Hz files during special events or requested 1-Hz;
the bottom entry represents streamed 1-Hz data.) Even though the timecode files have
a resolution at the hourly level, the bottom Temporal panel of the DAI is only showing
whether the UNAVCO archive has data or not at daily resolution.

Historical note: Even though UNAVCO only started collecting this timecode information
via teqc in mid-2006, all archived data prior to that was reprocessed in order to complete
the timecode files. This was orchestrated and mainly tackled by David Maggert in our group;
doing this, in addition to his normal day-to-day tasks, took about a year and half to
complete for both permanent stations and campaign sites.

Happy teqc-ing!


Louis H. Estey, Ph.D.               office: [+001] 303-381-7456
UNAVCO, 6350 Nautilus Drive            FAX: [+001] 303-381-7451
Boulder, CO 80301-5554              e-mail:    lou unavco.org

"If the universe is the answer, what is the question?"
                                                -- Leon Lederman

Past helpful tips:

week 1894: using teqc config files - https://postal.unavco.org/pipermail/teqc/2016/002067.html
week 1895: qc of high-rate data - https://postal.unavco.org/pipermail/teqc/2016/002071.html
week 1896: UNIX/Linux shells for Windows - https://postal.unavco.org/pipermail/teqc/2016/002072.html
week 1897: '-' vs. '+' teqc options - https://postal.unavco.org/pipermail/teqc/2016/002076.html
week 1898: auto-identification of formats - https://postal.unavco.org/pipermail/teqc/2016/002092.html
week 1899: auto-identification vs. format flags - https://postal.unavco.org/pipermail/teqc/2016/002096.html
week 1900: square brackets in options - https://postal.unavco.org/pipermail/teqc/2016/002105.html
week 1901: using option '+mds' - https://postal.unavco.org/pipermail/teqc/2016/002108.html
week 1902: qc results w/ problematic nav messages - https://postal.unavco.org/pipermail/teqc/2016/002113.html
week 1903: '-no_orb[it]' and '-no_pos[ition]' options - https://postal.unavco.org/pipermail/teqc/2016/002115.html
week 1904: '-week' option - https://postal.unavco.org/pipermail/teqc/2016/002117.html
week 1905: using '+bcf' for XYZ/geodetic conversion - https://postal.unavco.org/pipermail/teqc/2016/002126.html
week 1906: the '+v[erify]' option - https://postal.unavco.org/pipermail/teqc/2016/002128.html
week 1907: '+C2', '+L5', "+L6', '+L7', '+L8', '+all' options - https://postal.unavco.org/pipermail/teqc/2016/002130.html
week 1908: getting RINEX doppler and L2 - https://postal.unavco.org/pipermail/teqc/2016/002131.html
week 1909: using paths w/ file names - https://postal.unavco.org/pipermail/teqc/2016/002132.html
week 1910: the (un)importance of file names - https://postal.unavco.org/pipermail/teqc/2016/002133.html
week 1911: notices, warnings, and errors - https://postal.unavco.org/pipermail/teqc/2016/002134.html
week 1912: the '-max_rx_SVs' option - https://postal.unavco.org/pipermail/teqc/2016/002137.html
week 1913: the end of '++igs' and '+igs' - https://postal.unavco.org/pipermail/teqc/2016/002140.html
week 1914: splicing together RINEX files - https://postal.unavco.org/pipermail/teqc/2016/002144.html
week 1915: using '-O.int' and '-O.dec' - https://postal.unavco.org/pipermail/teqc/2016/002145.html
week 1916: '+doy' option - https://postal.unavco.org/pipermail/teqc/2016/002146.html
week 1917: '-tbin' and '-ast' options - https://postal.unavco.org/pipermail/teqc/2016/002152.html
week 1918: mp12 RMS before/after Oct 2013 - https://postal.unavco.org/pipermail/teqc/2016/002158.html
week 1919: the global windowing options - https://postal.unavco.org/pipermail/teqc/2016/002159.html
week 1920: '-M.dec' and '-N.dec' options - https://postal.unavco.org/pipermail/teqc/2016/002163.html
week 1921: combining time filtering options - https://postal.unavco.org/pipermail/teqc/2016/002176.html
week 1922: helping me (or someone else on the list) help you - https://postal.unavco.org/pipermail/teqc/2016/002187.html
week 1923: the "build" line - https://postal.unavco.org/pipermail/teqc/2016/002190.html
week 1924: the qc '-w[idth]' option - https://postal.unavco.org/pipermail/teqc/2016/002193.html
week 1925: qc with explicit time windowing - https://postal.unavco.org/pipermail/teqc/2016/002194.html
week 1926: the '+rx_state' option - https://postal.unavco.org/pipermail/teqc/2016/002200.html
week 1927: the '-O.sum' option - https://postal.unavco.org/pipermail/teqc/2016/002204.html
week 1928: the '+meta' and '+mds' options - https://postal.unavco.org/pipermail/teqc/2016/002206.html
week 1930: more on '-O.sum' - https://postal.unavco.org/pipermail/teqc/2017/002207.html
week 1931: the '-O.s[ystem]' option - https://postal.unavco.org/pipermail/teqc/2017/002208.html
week 1932: leap seconds - https://postal.unavco.org/pipermail/teqc/2017/002215.html
week 1936: what you can (and shouldn't) do in a RINEX obs file - https://postal.unavco.org/pipermail/teqc/2017/002229.html
week 1938: the '+psp' option - https://postal.unavco.org/pipermail/teqc/2017/002231.html
week 1939: the '+diag' option - https://postal.unavco.org/pipermail/teqc/2017/002235.html
week 1951: '-n_<system>' and SV filtering options - https://postal.unavco.org/pipermail/teqc/2017/002277.html
week 1953: more with '+diag' option - https://postal.unavco.org/pipermail/teqc/2017/002287.html
week 1954: using '+diag' output to split raw files - https://postal.unavco.org/pipermail/teqc/2017/002290.html
week 1955: current qc notation - https://postal.unavco.org/pipermail/teqc/2017/002302.html
week 1956: the '+qcq' option - https://postal.unavco.org/pipermail/teqc/2017/002304.html
week 1957: using Trimble formats - https://postal.unavco.org/pipermail/teqc/2017/002305.html
week 1958: ToC != ToE messages - https://postal.unavco.org/pipermail/teqc/2017/002310.html
week 1959: receivers vs. formats - https://postal.unavco.org/pipermail/teqc/2017/002311.html
week 1960: when the '-week' option is very wrong to use - https://postal.unavco.org/pipermail/teqc/2017/002314.html
week 1961: "less" is usually best - https://postal.unavco.org/pipermail/teqc/2017/002315.html
week 1962: using GPS L2C with teqc - https://postal.unavco.org/pipermail/teqc/2017/002316.html
week 1964: the '+eds' options - https://postal.unavco.org/pipermail/teqc/2017/002317.html
week 1965: handling RINEX comment lines - https://postal.unavco.org/pipermail/teqc/2017/002324.html
week 1966: the '+dUTC_p' options - https://postal.unavco.org/pipermail/teqc/2017/002331.html
week 1967: the strange position from '+meta' - https://postal.unavco.org/pipermail/teqc/2017/002355.html
week 1972: what shows up as metadata in RINEX headers - https://postal.unavco.org/pipermail/teqc/2017/002362.html
week 1973: GPS L2C navigation messages - https://postal.unavco.org/pipermail/teqc/2017/002363.html
week 1974: the '+ion_p' options - https://postal.unavco.org/pipermail/teqc/2017/002370.html
week 1975: the '+event' options - https://postal.unavco.org/pipermail/teqc/2017/002372.html
week 1976: options '+smtt' (default) vs. '-smtt' - https://postal.unavco.org/pipermail/teqc/2017/002374.html
week 1977: the reported interval with '+meta' for a RINEX obs file - https://postal.unavco.org/pipermail/teqc/2017/002377.html
week 1978: the '-N.dUTC' options - https://postal.unavco.org/pipermail/teqc/2017/002378.html
week 1979: the various qc elevation angles - https://postal.unavco.org/pipermail/teqc/2017/002383.html
week 1980: avoid in RINEX: Transit data - https://postal.unavco.org/pipermail/teqc/2017/002385.html
week 1981: avoid in RINEX: epoch flag = 6 - https://postal.unavco.org/pipermail/teqc/2017/002389.html
week 1982: avoid in RINEX: RCV CLOCK OFFS APPL = 1 - https://postal.unavco.org/pipermail/teqc/2018/002392.html
week 1983: don't count on in RINEX: receiver clock offset per epoch - https://postal.unavco.org/pipermail/teqc/2018/002393.html
week 1984: requirements for multiple target files/stdin - https://postal.unavco.org/pipermail/teqc/2018/002410.html
week 1985: default output for various input - https://postal.unavco.org/pipermail/teqc/2018/002412.html
week 1986: the '+latency' options - https://postal.unavco.org/pipermail/teqc/2018/002419.html
week 1987: the 'O.px and 'O.pg' options - https://postal.unavco.org/pipermail/teqc/2018/002422.html
week 1988: the '+relax' option - https://postal.unavco.org/pipermail/teqc/2018/002423.html
week 1992: the '+x_tilt' options - https://postal.unavco.org/pipermail/teqc/2018/002452.html
week 1993: GLONASS: slot and freq. chnl. numbers - https://postal.unavco.org/pipermail/teqc/2018/002453.html
week 1994: GLONASS: slot numbers > 24 - https://postal.unavco.org/pipermail/teqc/2018/002454.html
week 1995: GLONASS: signals - https://postal.unavco.org/pipermail/teqc/2018/002456.html
week 1996: GLONASS: broadcast ephemeris - https://postal.unavco.org/pipermail/teqc/2018/002457.html
week 1997: GLONASS: system time and broadcast time parameters - https://postal.unavco.org/pipermail/teqc/2018/002458.html
week 1998: qc: 'lite' vs. 'full' - https://postal.unavco.org/pipermail/teqc/2018/002470.html
week 1999: qc: the 'full' point-position and the antenna 'height' - https://postal.unavco.org/pipermail/teqc/2018/002474.html
week 2000: qc: what's a "complete observation"? - https://postal.unavco.org/pipermail/teqc/2018/002475.html
week 2001: qc: percentage of actual to expected complete observations - https://postal.unavco.org/pipermail/teqc/2018/002483.html
week 2014: qc: interpreting slips - https://postal.unavco.org/pipermail/teqc/2018/002521.html
week 2015: qc: loss-of-lock - https://postal.unavco.org/pipermail/teqc/2018/002524.html
week 2016: qc: observations per slip - https://postal.unavco.org/pipermail/teqc/2018/002526.html
week 2017: qc: multipath rms - https://postal.unavco.org/pipermail/teqc/2018/002527.html
week 2018: qc: signal-to-noise - https://postal.unavco.org/pipermail/teqc/2018/002532.html
week 2019: qc: the ASCII time plot - https://postal.unavco.org/pipermail/teqc/2018/002534.html
week 2020: qc: little known (but sometimes useful) options - https://postal.unavco.org/pipermail/teqc/2018/002535.html
week 2021: qc: qc full: the '-dn' and '+dn' ASCII time plot lines, part I - https://postal.unavco.org/pipermail/teqc/2018/002544.html
week 2022: qc: qc full: the '-dn' and '+dn' ASCII time plot lines, part II - https://postal.unavco.org/pipermail/teqc/2018/002554.html
week 2023: qc: point-position elevation restrictions - https://postal.unavco.org/pipermail/teqc/2018/002556.html
week 2024: qc: main "filtering" possibilities - https://postal.unavco.org/pipermail/teqc/2018/002557.html
week 2025: qc: expectations for teqc's PP in Solar Cycle 25 - https://postal.unavco.org/pipermail/teqc/2018/002558.html
week 2026: qc: when the antenna is moving (a lot) - https://postal.unavco.org/pipermail/teqc/2018/002564.html
week 2027: qc: direct quality check of raw data - https://postal.unavco.org/pipermail/teqc/2018/002569.html
week 2028: navigation message intervals and using '-tbin' - https://postal.unavco.org/pipermail/teqc/2018/002578.html
week 2029: the '-ns' and '-ne' time windowing options - https://postal.unavco.org/pipermail/teqc/2018/002579.html
week 2030: "no routine" messages in stderr - https://postal.unavco.org/pipermail/teqc/2018/002580.html
week 2031: why zero-length files that are created are left in place - https://postal.unavco.org/pipermail/teqc/2018/002581.html
week 2032: reasons 1-6 that navigation messages might be discarded - https://postal.unavco.org//pipermail/teqc/2018/002596.html
week 2033: reasons 7-11 that navigation messages might be discarded - https://postal.unavco.org//pipermail/teqc/2018/002602.html
week 2034: Lou's list of most used options (and why) - https://postal.unavco.org//pipermail/teqc/2019/002603.html
week 2035: the most likely causes of slips - https://postal.unavco.org//pipermail/teqc/2019/002609.html

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