[teqc] Teqc and dat2rin

[Lou Estey]

Dear Germinal,

> An example of tranlation with TEQc and DAT2RIN (Trimble) :
> 
> teqc  2005Nov4      GG            20060602 15:07:41UTCPGM / RUN BY / DATE
>      4    L1    L2    C1       P2                # / TYPES OF OBSERV
>  06  4  1 15  0  0.0000000  0  6G28G26G29G17G 8G10
>  -21199884.02448 -16512048.86046  20847914.1884  20847912.7344
>  -10961550.02647  -8528635.11645  23038562.4144  23038561.3954
>  -15878111.44248 -12359263.80145  21465889.1254  21465888.3364
>  -11858818.69747  -9220907.41845  22499612.8834  22499613.0004
>   -7269717.27447  -5646946.39944  23057384.8364  23057385.5824
>  -20735670.86548 -16137814.96046  20875807.4384  20875806.4734
> 
> DAT2RIN 3.46        GG            02JUN06 11:05:15    PGM / RUN BY / DATE
>      4    L1    C1    L2    P2                    # / TYPES OF OBSERV
>  06  4  1 15  0  0.0000000  0  6  8 10 17 26 28 29
>   -7269717.27406  23057384.83606  -5646946.39947  23057385.58247
>  -20735670.86507  20875807.43807 -16137814.96048  20875806.47348
>  -11858818.69706  22499612.88306  -9220907.41848  22499613.00048
>  -10961550.02606  23038562.41406  -8528635.11647  23038561.39547
>  -21199884.02407  20847914.18807 -16512048.86048  20847912.73448
>  -15878111.44207  21465889.12507 -12359263.80148  21465888.33648
> 
> 
> 1/ Could you tell me why the four digit is always 4 with TEQC
> 2/ Could you tell me why with DAT2RIN the four digit is always 4 (f2)
>                                                             or 0 (f1)

Of course there are only 3 digits to the reporting precision of any
observable in RINEX.  The "4th digit" reflects loss-of-lock, full-
vs. half-wavelength tracking of phase, and antispoofing status of
a GPS SV:

1 = loss-of-lock
2 = half-wavelength
4 = antispoofing on

With values of just 0 and 4, only antispoofing is being reported
(i.e. there is no loss-of-lock being reported and phase is full-wavelength
tracking).

dat2rin chooses to put the antispoofing flag just on the L2 phase
and code pseudorange observables, probably because the L2 is collected
with a cross-correlation method.

teqc puts the antispoofing flag on all the observables (when translating
Trimble .dat or RT17 formats), viewing antispoofing more of a characteristic
of the SV; thus you can find the antispoofing status by observing any of
the observables.   In other words, AFAIK, if antispoofing is on, it's
on for both frequencies, regardless of how the signals are detected and
tracked.

The short answer: it's a philosophical difference.  There are pros and
cons for both ways of reporting the antispoofing status.

cheers,
--lou

p.s.  ... and of course the "5th digit" is a 0-9 representation of
the SNR; dat2rin and teqc and other translators use different algorithms,
though this mapping is standardized in RINEX 3.00 if the SNR is recoverable
in dBHz, and teqc versions as of 2 Aug 2005 use this standardized mapping
even in RINEX 2.xx.

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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
    WWW:  http://www.unavco.org   http://jules.unavco.org

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