[teqc] Sasa Lazic Question dn

Lou Estey lou at unavco.org
Thu Aug 19 07:58:18 MDT 2010


Dear Sasa,

> I need a little help with interpreting the graphic that comes command
> + Qc. Part of the graphic is shown in the picture below.
>
> -dn|+  ++ + + ++++ ++  + ++ +++++   ++ +++ + + ++ ++ ++ +++++  ++++         |-dn
> +dn|                      e ee              e                               |+dn
> +10|aaaa98888888889999a9a999977888999998999979aa8889998888997999a88abaa9999a|+10
> Pos|oo o                    oo             oo                               |Pos
> Clk|                      ^ ^^              ^                               |Clk

(The above is just an approximation of what was sent -- it would have been
better to send things like that in a non-proportional font.)

> What do the labels + in the line -dn?

This means there are epochs in these columns in the plot that have a complete
set of dual-frequency data below the qc elevation mask (which in this case is
10 degrees, as seen by the '+10').

> What do the labels in the line of the e +dn?

This means there are epochs in these columns in the plot that are missing
0xe = 14 SVs.  Given that these look like they match up with the '^' symbols
on the Clk line, the value of "14" for the maximum number of SVs must have
been set automatically by teqc based on the receiver type or by you (with
the '-max_rx_SVs' option).

Everything except the '+' is explained in
http://facility.unavco.org/software/teqc/tutorial.html#sec_21
The '+' indicators are relatively new, introduced in Mar 2009, and are
explained in more detail here:
http://ls.unavco.org/pipermail/teqc/2009/000803.html

For all you nitpickers :) the characters used in the -dn and +dn aren't
hexadecimal (base-16).  They are currently base-25 so they will go continue
from 'f' for 15 to 'o' for 24 and then for larger values you'll see '-'.
This seemed like a pretty sensible limit when GNSS receivers where mainly
tracking GPS and the GLONASS constellation was still somewhat incomplete.
Given the upcoming GNSS possibilities in the next few years, this will
probably have to be increased for potential simultaneous tracking of 40+
GNSS SVs (GPS, GLONASS, Galileo, Compass, QZSS, rest of SBAS, ...).
The good news is that this is a very trivial change to make in the teqc
code.

cheers,
--lou

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Louis H. Estey, Ph.D.              office:  [+001] 303-381-7456
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                                                -- Leon Lederman
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