2.6.3 RA-2/MWR Level 1b product
The RA-2/MWR level 1b
product contains the geolocated
engineering calibrated data. When creating
the L1b product, the raw Level 0 data is
converted into engineering units and the
relevant instruments calibration and
characterisation data is applied.
Although two different
products (RA2_ME__0P and MWR_NL__0P) are
needed as input, only one merged RA-2/MWR
product is created at Level 1b, containing
the meaningful results from both the RA2 and
the MWR Level 1b processing activities.
The RA-2/MWR Level 1b
product is composed of an MPH and SPH
(common to both instruments) and 4
Measurement Data Sets (RA2, individual
echoes waveforms, RA-2 Point Target Response
The layout of the MPH is
common to all EnviSat instruments and
contains information such as the first/last
record time in the product, UTC/SBT time
reference table, Orbit State Vector
information, SPH size and total product size.
The SPH and the Data Sets
are instead specific of each product and
of each processing level.
The SPH cotnains information
concerning the whole product, while the
Measurement Data Sets contain information
specific of every record.
Each MDS record includes a
time record, a quality indicator flag
and a record counter inside the product.
The RA2 and MWR MDSRs
contain the latitude and longitude value
of every record, quality fields (MCD) and
the science data.
18.104.22.168 RA-2/MWR Level 1b SPH
The unique RA-2/MWR L1b SPH
contains information coming from both
the RA2 and MWR Level 1b processing steps.
The start/stop latitude and
longitude values for RA2 and MWR records
are contained in the SPH, along with the
first and last record times for both instruments.
Quality flags indicating if
the percentage of records with header or
processing errors (for RA2) or header,
telemetry and processing errors (for MWR) is
less than a threshold (extracted from the
auxiliary configuration files) are included.
Information like percentage
of records in the different RA2
operational modes, and percentage of the RA2
records in the different Ku bandwidths
appears in the L1b SPH as well.
22.214.171.124 Level 1b RA2 MDS
This RA2 Level 1b Data Set
shall reflect the structure and contents
of the input RA2 Level 0 Source Packets,
with values converted into engineering units
and all RA2 calibration and characterisation
One output record is
generated for each Data Block of the Level
0 Source Packets. In other words, one output
record represents one elementary measurement
corresponding to about 55.7 milliseconds of
Some information in these
output records come from the Source
Packet Header, and so, it will be repeated
for the 20 records corresponding to the same ISP.
Instead. some other values
are Data Block dependant, meaning that
different values will be output for every
L1b record of the same ISP.
The Ku/S IF mask corrected
waveform samples, including the 2 DFT
extra samples are included in the RA2 L1b
records, along with the main output results
from the AGC processing (corrected Ku abdn
and S band AGC, scaling factors for
sigma_0 evaluation for both bands, etc.),
PTR processign (time delay and sigma_0
flight calibration factors for both
bands), window delay for Ku and S,
calibrated Noise Power Measurement, Doppler
correction for Ku and S, Delta_Offset, etc.
Most of the fields in these
records are meaningful only if mode_id
at DB level is Tracking, Preset Tracking or
Preset Loop Output. Otherwise, default
values (0) are used to fill those fields in.
Nevertheless, fields like
UTC time, latitude, longitude, DB
number, record counter, etc., are always
correctly filled in independantly of the
mode of the instrument.
126.96.36.199 Level 1b RA2 individual echoes
This MDS contains the
unaveraged individual echoes appended to
the Level 0 RA2 ISPs.
This MDS will only be
present in the L1b product if there are
RA2 Level 0 ISPs with individual echoes present.
These records include always
a time (that corresponds to the time of
the first DB of the first ISP containing
individual echoes), an OBDH datation (that
coincides with the OBDH value from the first
ISP containing individual echoes, and that
does not change for all the individual
echoes waveforms records in the same
sequence), a record counter, a source
sequence counter (extracted from the header
of the first ISP in the sequence of
individual echoes) and the individual
The individual echoes field
contains the In-Phase and Quadrature
samples, corresponding each to an 8 bit
two's complement value from the Level 0 field.
188.8.131.52 Level 1b PTR MDS
This MDS consists of data
output from the PTR processing
operations in the Level 1b processing
algorithms. The rate of these records is one
every 1.114 seconds (same rate as the Level
0 RA2 ISPs, since the PTR data is
included in the calibration field at the end
of the ISPs).
These records include a time
value, an OBDH datation word (copy of
the value in the L0 ISP), a record counter,
the 128 normalised PTR processed samples,
the time delay and sigma_0 flight
calibration factors, and some other flags.
The flight calibration
factors are repeated in the main RA2 L1b
MDSRs as well.
184.108.40.206 Level 1b MWR MDS
Each record in this MDS
represents data coming from 8 scans of
the radiometer, i.e. 1.2 seconds of data, so
that it is available at a rate similar to
RA2 (1.114 seconds).
No further averaging is
performed when processing from L1b to
L2, thus, the same record format is used for
both processing levels.
In each record, datation and
geolocation are included, together with
some flags (MCD) to describe the validity of
each output. Some instrument flags are also
inserted in each record to give some
information on instrument status at the
The fields that are filled
in at Level 2, are set to 0 when
outputting the L1b product.