SEPTENTRIO PolaRx5S, User Manual

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5.3. SBF2 I SMR PROGRAM
TEC
TEC and dTEC values (both in TECU unit) are provided in columns 17-24.
Absolute TEC values are reported every 15 seconds (there are 4 TEC columns per I SMR
record) which are based on dual-frequency pseudorange measurements only. dTEC values
report the change of TEC over the four 15-second intervals of the previous minute. dTEC is
computed from the carrier phase measurements only.
I t is much more accurate than TEC
but only gives information on the TEC variation over time.
Note that absolute TEC values can be biased by satellite and station inter-frequency biases.
Sources of station biases include the antenna, the antenna cable, splitters, ampli
fi ers, and
the receiver.
The table below lists the signals used for each constellation in the determination of TEC
values as well as how the satellite biases are handled for that constellation.
Satellite
system TEC signal
combination
Default handling of satellite-induced biases
GPS * L1P-L2P The correction (T
GD
) transmitted by GPS satellites is applied.
GLO L1CA-L2CA Uncorrected
GAL E1-E5a
The correction (BGD(E1,E5a)) transmitted by Galileo satellites
is applied.
BDS B1-B2
The correction (T
GD 1
, T
GD 2
) transmitted by BeiDou satellites
is applied.
QZSS L1CA-L2C The correction (T
GD
) transmitted by QZSS satellites is applied.
SBAS L1CA-L5 Uncorrected
I RNSS -
Only one frequency (L5) of I RNSS satellites is available so not
possible to determine TEC values.
∗
For GPS, the TEC is based on the P-code measurements (as opposed to the C/A-code) on L1 and L2. There is
therefore no need for correction of the L1P-L1CA satellite biases.
I t is possible to disable the correction of the satellite inter-frequency biases, i.e. to ignore the
corrections transmitted by the satellites. This is done using the option ‘
-g
’ with
sfb2ismr
Station biases (and residual satellites biases) can be provided in a TEC calibration fi le using
the ‘
-C
’ option with
sfb2ismr
. See the help text in Section 5.3 for the TEC calibration fi le
format.
sfb2ismr
can be used to generate the calibration fi le. See Appendix G for details.
Note that, by default, the receiver does not apply any code smoothing which results in noise
of a few TECUs on the TEC values. To reduce the noise at the expense of
fi ltering short-term
TEC variations, code smoothing can be enabled using the ‘
setSmoothingInterval
’
command on the receiver. This remark does not apply to dTEC, which is computed on the
basis of carrier phase measurements.
Scintillation Index
The S I index (columns 29, 43 and 57) is computed as follows:
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