Minimize Level 1b Product Format


General Structure of Product

The structure of the products produced for delivery to the PDGS must follow the requirements of [AD-12] as represented in Figure 1 below.

Figure 1:  Level 1b general product structure

Figure 1: Level 1b general product structure

Each product comes in a zip file composed of one XML Header file and one or more Product Files:

  • XML Header Files have extension .HDR
  • Product Files have extensions .cdf, .sp3 or .rnx (see Table 1 in Level 1b Product Definitions for details)


The XML Header (logical) file is an ASCII file containing data information that users can easily access for identifying the product without needs to look inside the Product File.

It consists of (see [AD-5] for details):

  • Fixed Header, a common header for all files in the Swarm Ground Segment
  • Variable Header, including
  • Main Product Header (MPH) containing general information, which is common to all Swarm products
  • Specific Product Header (SPH) containing product specific and product-wide information. The Specific Product Header will also contain the Data Set Descriptors (DSDs) which provide information on the attached Data Sets and references to external files (input files) relevant for the current product

The Product Files are the real products containing the processing results. The Product Files comprise one Data Set (DS) containing the processing results and related information. A Data Set contains one or more Data Set Records (DSRs). CDF file products will also include the Specific Product Information from the Specific Product Header as global attributes. See Section Level 1b Products Variable Header (Product Header) for details.




XML Header File

The XML Header file contains information identifying the product. It is composed by:

  • a Fixed Header
  • a Variable Header

The Fixed Header (hereafter called Standard Swarm Header) is the common header for all files in the Swarm Ground Segment, which means it is applied to all files flowing amongst the sub-systems composing the PDGS.

The format of the Standard Swarm Header is under ESA responsibility and is specified in [AD-12] and [AD-13].

The Variable Header (hereafter called Product Header) is the header with format and content depending on the file type and kind of product.

The next sub-paragraphs specify the content of these headers.




Level 1b Products Fixed Header (Standard Swarm Header)

The Standard Swarm Header is completely ASCII and based on XML syntax and conventions proposed in [AD-12].

It has the same format as for the Level 0 products [AD-14] with suitable settings for the Level 1b Processor:

Field Content Comment
File_Description See Table 1 in Level 1b Product Definitions.  
Validity_Period.Validity_Start Effective start time of product (time of first data set record in product)

In case of MAGXMAN_1B (MAGXMAN_1B Data Set Record), the validity stop equals the validity start of the second ASM_VFM_IC record.

In the case of RINEX products, GPSX_R?_1B, the products follow the GPS days (and use GPS time in the RINEX product files), hence they start some seconds before UTC midnight; e.g. in 2013 GPS days start at 23:59:44 UTC.

Validity_Period.Validity_Stop Effective stop time of product (time of last data set record in product)
Source.System APDF  
Source.Creator L1B  
Source.CreatorVersion Job order verion  

Table 1: Standard Swarm Header




Level 1b Products Variable Header (Product Header)

The XML Variable Header (hereafter called Product Header) for the Level 1b products is composed by:

  • an XML Main Product Header (XML MPH)
  • an XML Specific Product Header (XML SPH)

The XML MPH structure is common to all products while the XML SPH contains different information among the products.

Each header is completely ASCII and based on XML syntax and conventions proposed in the [AD-12].


XML Main Product Header (XML MPH)

The Main Product Header (MPH) has the following format - very similar to the Level 0 Main Product Header [AD-14], see also [AD-13]:

Field # Description Units Bytes[1] Format
1 MPH Tag    
1.1 Product Tag    
Product file name (without extension)

See File Names

  55 55*uc
1.2 Proc_Stage_Code Tag    
Processing stage code:

OPER = Routine operations
TEST = Test
RPRO = Re-processing

  4 4*uc
1.3 Ref_Doc Tag    
Reference DFCB Document describing the product: SW-RS-DSC-SY-0007     *uc
Data Processing Information
1.4 Acquisition_Station Tag    
Acquisition Station ID:

KSS = Kiruna
SGS = Svalbard

  3 3*uc
1.5 Proc_Center Tag    
Processing Center ID code:

FRB = Farnborough

  3 3*uc
1.6 Proc_Time Tag    
Processing Time, UTC

(Product Generation Time)

  30 UTC=yyyy-mm-dd

Thh:mm:ss.uuuuuu

1.7 Software_Version Tag    
Processor Name and software version number     ProcessorName/VV.rr

(*uc)

Orbit Information
1.8 Abs_Orbit_Start Tag    
Absolute orbit number at start of data.

If not used set to "000000"

  6  %06d
1.9 Abs_Orbit_Stop Tag    
Absolute orbit number at end of data.

If not used set to "000000"

  6  %06d
1.10 State_Vector_Time Tag    
UTC state vector time = sensing start time of product   30 UTC=yyyy-mm-dd

Thh:mm:ss.uuuuuu

1.11 Delta_UT1 Tag    
Universal Time Correction:

DUT1 = UT1 – UTC.
If not used set to "+.000000"

  9  %+9.6f
1.12 X_Position Tag    
X position in ECEF at start of product.

If not used set to "+0000000.000"

m 12  %+012.3f
1.13 Y_Position Tag    
Y position in ECEF at start of product.

If not used set to "+0000000.000"

m 12  %+012.3f
1.14 Z_Position Tag    
Z position in ECEF at start of product.

If not used set to "+0000000.000"

m 12  %+012.3f
1.15 X_Velocity Tag    
X velocity in ECEF at start of product.

If not used set to "+0000.000000"

m/s 12  %+012.6f
1.16 Y_Velocity Tag    
Y velocity in ECEF at start of product.

If not used set to "+0000.000000"

m/s 12  %+012.6f
1.17 Z_Velocity Tag    
Z velocity in ECEF at start of product.

If not used set to "+0000.000000"

m/s 12  %+012.6f
1.18 State_Vector_Source Tag    
Source of Orbit State Vector Record

MD = Medium Precision Orbit Determination

  2 2*uc
Product Confidence Data Information
1.19 Product_Err Tag    
Product Error Flag. Set to 0 if all flags are within limits; set to 1 if any flag is above limit specified in CCDB, [RD-1]   1 uc
Product Size Information
1.20 Tot_Size Tag    
unit="bytes" Attribute    
Total size of product bytes 21  %+021d
1.21 CRC Tag    
Cyclic Redundancy Code computed as overall value of all records of the Measurement Data Set.

If not computed it shall be set to "-00001"

  6  %+06d

Table 2: Level 1b Main Product Header (MPH)

[1] Actually this column is redundant but listed for information only. Some field value lengths are not known, for these no information in "Bytes" column is given.

XML Specific Product Header (XML SPH)

The formats of the Specific Product Headers (SPHs) are described next. The SPHs consist of a common part described first and small product specific parts described afterwards.

Field # Description Units Bytes Format
1 SPH Tag    
1.1 SPH_Descriptor Tag    
Name describing the Product.

"File Type" column of Table 1 in Level 1b Product Definitions

  10 10*uc
Information on Time and Orbits of Data
1.2 Orbit_Information Tag    
1.2.1 Sensing_Start Tag    
Start time in UTC of sensing data   30 UTC=yyyy-mm-dd

Thh:mm:ss.uuuuuu

1.2.2 Sensing_Stop Tag    
Stop time in UTC of sensing data   30 UTC=yyyy-mm-dd

Thh:mm:ss.uuuuuu

Maneuver Information – distinct maneuvers chronologically detected
1.3 Maneuver_Information Tag    
count="n" Attribute    
1.3.i Maneuver_Id Tag    
The ith, distinct maneuver identification      
Maneuver identification code, see [RD-3]   3  %03d
Specific Product Information
1.4 The various products may have specific product information, see Table 5 through Table 10 below
Product Confidence Section – various information on the quality of the Product, such as number of missing or erroneous ISPs (Instrument Source Packets) and number of rejected or suspicious samples. Fields 1.5.2-1.5.4 are not used for MAGXMAN_1B
1.5 Product_Confidence_Data Tag    
1.5.1 Quality_Indicator Tag    
Generel product quality indicator   3  %03d
1.5.2 HK_ISP_Missing Tag    
Number of missing/erroneous platform HK ISPs   5  %05d
1.5.3 GPSR_ISP_Missing Tag    
Number of missing/erroneous GPSR ISPs   5  %05d
1.5.4 STR_ISP_Missing Tag    
Number of missing/erroneous STR ISPs   5  %05d
  Additional, Product specific fields are listed in Table 5 through Table 10 below.

 

Further fields may be added as needed.

Data Set Description Section
1.6 List_of_DSDs Tag    
count="n" Attribute    
Data Set Descriptor – this part is repeated n times, one for each Data Set (DS)
1.6.i DSD Tag    
Data Set i descriptor, i = 1,2,…,n      
1.6.i.1 Data_Set_Name Tag    
Name of Data Set.

If measurement data, Data Set Name (see Table 11).
If reference file, File Type part of the referenced file (Section 4.1.3 of [AD-13])

    *uc
1.6.i.2 Data_Set_Type Tag    
Type of Data Set:

M - measurement (e.g.MDR_Mag_HR)
R – reference (see Input Files)

  1 uc
1.6.i.3 File_Name Tag    
Name of referenced file; if CCDB file extension (".EEF") is included, otherwise without extension.

Fill with blanks if Data_Set_Type ≠ "R"

  55 or 59 55*uc or 59*uc
1.6.i.4 Data_Set_Offset Tag    
unit="bytes" Attribute    
Offset (in bytes) of first byte of first DS record within Product File.

Only used if Data_Set_Type = "M", otherwise set to zeros.

bytes 21  %+021d
1.6.i.5 Data_Set_Size Tag    
unit="bytes" Attribute    
Total number of bytes in DS

Only used if Data_Set_Type = "M", otherwise set to zeros.

bytes 21  %+021d
1.6.i.6 Num_of_Records Tag    
Number of Data Set records

Only used if Data_Set_Type = "M", otherwise set to zeros.

  11  %+011d
1.6.i.7 Record_Size Tag    
unit="bytes" Attribute    
Size of Data Set records

If variable set to -0000000001

Only used if Data_Set_Type = "M", otherwise set to zeros.

bytes 11  %+011d
1.6.i.8 Byte_Order Tag    
Byte ordering information.

3210 → Big-endian
0123 → Little-endian
Only used if Data_Set_Type = "M", otherwise set to "0000".

  4 4*uc

Table 3: Level 1b Specific Product Header (SPH)


The MAGX_HR_1B and MAGX_LR_1B Product SPHs shall contain the specific parts:

Field # Description Units Bytes Format
Magnetic Product Information
1.4 Magnetic_Information Tag    
1.4.1 q_STR_VFM Tag    
Quaternion from CRF (of STR) to VFM

 

CCDB.Structure.STR_q_VFM

     
1.4.1.i Qi (i = 1,2,3,4) Tag    
ith quaternion component   13  %+13.10f
1.4.2 r_CoG_VFM Tag    
Vector from S/C center of gravity to VFM, S/C frame      
1.4.2.i X, Y, Z (i = 1,2,3 respectively) Tag    
  m 6  %+6.3f
Product Confidence Section
1.5.5 VFM_ISP_Missing Tag    
Number of missing/erroneous VFM ISPs   5  %05d
1.5.6 VFM_Samples_Rejected Tag    
Number of rejected VFM samples   7  %07d
1.5.7 VFM_Suspicious_Samples Tag    
Number of suspicious VFM samples   7  %07d
1.5.8 ASM_ISP_Missing Tag    
Number of missing/erroneous ASM ISPs
MAGX_LR_1B Product only
  5  %05d
1.5.9 ASM_Samples_Rejected Tag    
Number of rejected ASM samples
MAGX_LR_1B Product only
  5  %05d
1.5.10 ASM_Suspicious_Samples Tag    
Number of suspicious ASM samples
MAGX_LR_1B Product only
  5  %05d

Table 4: MAGX_HR_1B and MAGX_LR_1B SPH - Specific Parts


The ASMXAUX_1B and VFMXAUX _1B Product SPHs shall contain the specific parts:

Field # Description Units Bytes Format
Magnetic Product Information
1.4 Magnetic_Stray_Fields Tag    
1.4.1 VFM_q Tag    
Transformation from S/C to VFM sensor frame, CCDB.Structure.VFM_q      
1.4.1.i Qi (i = 1,2,3,4) Tag    
ith quaternion component   13  %+13.10f
1.4.2 ASM_q_VFM      
Transformation from VFM sensor to ASM sensor frame, CCDB.Structure.ASM_q_VFM      
1.4.2.i Qi (i = 1,2,3,4) Tag    
ith quaternion component   13  %+13.10f
Product Confidence Section
1.5.5 VFM_ISP_Missing Tag    
Number of missing/erroneous VFM ISPs   5  %05d
1.5.6 MTR_ISP_Missing Tag    
Number of missing/erroneous Magnetic Torquer HK ISPs   5  %05d
1.5.7 Bus_ISP_Missing Tag    
Number of missing/erroneous Bus Current HK ISPs   5  %05d

Table 5: ASMXAUX_1B and VFMXAUX _1B SPH - Specific Parts


The MAGX_CA_1B Product SPH shall contain the specific parts:

Field # Description Units Bytes Format
Magnetic Calibration Product Information
1.4 Mag_C_Information Tag    
1.4.1 ASM_Group_Delay Tag    
Group delay of ASM filter (CCDB.ASM.Filter.Delay) s 7  %+7.4f
Product Confidence Section
1.5.5 VFM_ISP_Missing Tag    
Number of missing/erroneous VFM ISPs   5  %05d
1.5.6 VFM_Samples_Rejected Tag    
Number of rejected VFM samples   7  %07d
1.5.7 VFM_Suspicious_Samples Tag    
Number of suspicious VFM samples   7  %07d
1.5.8 ASM_ISP_Missing Tag    
Number of missing/erroneous ASM ISPs   5  %05d
1.5.9 ASM_Samples_Rejected Tag    
Number of rejected ASM samples   5  %05d
1.5.10 ASM_Suspicious_Samples Tag    
Number of suspicious ASM samples   5  %05d

Table 6: MAGX_CA_1B SPH - Specific Parts


The MAGXMAN_1B Product SPH shall contain no specific Product Information parts.


The MODX_SC_1B, GPSX_RO_1B, and GPSX_RN_1B Product SPHs shall contain the specific Product Information part:

Field # Description Units Bytes Format
Position and RINEX Product Information
1.4 Ephemeris_Information Tag    
1.4.1 Mass_SC Tag    
Mass of the space craft at start of product kg 7  %7.3f
1.4.2 r_CoG_ARP Tag    
Vector from center of gravity to antenna reference point, S/C frame m 21 3 * " %+6.3f"
1.4.3 RINEX_Filename Tag    
Suggested name of RINEX file according to [RD-4] (not to be confused with 1.6.i.3 – the real filename of the Product File). Eg. ssssdddhmm.yyO

Only RINEX Products.
Value for MODX_SC_1B Product: ‘Not Appl.' (4 spaces between ‘Not' and ‘Appl.').

  12 12*uc

Table 7: MODX_SC_1B, GPSX_RO_1B, and GPSX_RN_1B SPH - Specific Part

The GPSXNAV_1B Product SPH shall contain no specific Product Information parts.


The STRXATT_1B Product SPH shall contain the specific Product Information parts:

Field # Description Units Bytes Format
Attitude Product Information
1.4 Attitude_Information Tag    
Product Confidence Section
1.5.5 STR_One_CHU_Missing Tag    
Number of attitude samples based on two camera heads (CHU)   5  %05d
1.5.6 STR_Two_CHU_Missing Tag    
Number of attitude samples based on one camera head only   5  %05d

Table 8: STRXATT_1B SPH - Specific Part


The EFIX_PL_1B, LP_X_CA_1B, and TIIX_CA_1B Product SPHs shall contain the specific Product Confidence part:

Field # Description Units Bytes Format
Plasma Product Information'''
1.4 Plasma_Information Tag    
Product Confidence Section
1.5.5 EFI_ISP_Missing Tag    
Number of missing/erroneous TII & LP science ISPs   5  %05d
1.5.6 LP_ISP_Missing Tag    
Number of missing/erroneous (pure) LP ISPs   5  %05d
1.5.7 TII_ISP_Missing Tag    
Number of missing/erroneous (pure) TII ISPs   5  %05d

Table 9: EFIX_PL_1B SPH - Specific Part


The ACCX_PR_1B Product SPH shall contain the specific Product Confidence part:

Field # Description Units Bytes Format
Acceleration Product Information'''
1.4 Acceleration_Information Tag    
Product Confidence Section
1.5.5 ACC_ISP_Missing Tag    
Number of missing/erroneous ACC ISPs   5  %05d
1.5.6 ACC_Samples_Rejected Tag    
Number of rejected ACC samples   5  %05d

Table 10: ACCX_PR_1B SPH - Specific Part




Input Files

Input files to the Level 1b Processor (Level 0, CCDB, and auxiliary files) used in the generation of the product are specified in the Data Set Descriptor (DSD) section of the SPH as "Reference" Data Sets – one DSD for each input file.

 



File Names

The file names of XML Header files and the ASCII file products (see Table 4-1 in [AD-5] for details) are defined in [AD-13], that is:

MM_CCCC_TTTTTTTTTT_yyyymmddThhmmss_YYYYMMDDTHHMMSS_vvvv.HDR

MM_CCCC_TTTTTTTTTT_yyyymmddThhmmss_YYYYMMDDTHHMMSS_vvvv.sp3

or

MM_CCCC_TTTTTTTTTT_yyyymmddThhmmss_YYYYMMDDTHHMMSS_vvvv.rnx

where the meaning of the elements composing the file name is described in [AD-13]. The start and stop times in the filename refer to sensing period (Shape 1 in Section 4.1.5.1 of [AD-13]).

The file names of the CDF file products (see Table 1 in Level 1b Product Definitions) are a combination of the operational product file names and the MDR names (see Table 11) of the individual MDR types that compose that specific product:

MM_CCCC_TTTTTTTTTT_yyyymmddThhmmss_YYYYMMDDTHHMMSS_vvvv_<MDR_Name>.cdf

For example, in case of the MAGX_HR_1B magnetic Level 1b product with 50 Hz data for the Swarm satellite A the names could be:

SW_OPER_MAGA_HR_1B_20090624T075728_20090624T080231_0001.HDR

SW_OPER_MAGA_HR_1B_20090624T075728_20090624T080231_0001_MDR_MAG_HR.cdf

SW_OPER_MAGA_HR_1B_20090624T075728_20090624T080231_0001_ASM_VFM_IC.cdf

The file with the extension .HDR is the XML Header file and the file with the extension .cdf is the Level 1b product file.

Zipfiles containing ASCII file products are named:

MM_CCCC_TTTTTTTTTT_yyyymmddThhmmss_YYYYMMDDTHHMMSS_vvvv.ZIP

whereas zipfiles containing CDF file products are named:

MM_CCCC_TTTTTTTTTT_yyyymmddThhmmss_YYYYMMDDTHHMMSS_vvvv.CDF.ZIP




Product File

The Product File will consist of a:

  • Measurement Data Block

The Measurement Data Block contains a specific number of Data Sets as defined in the Table below.

File Type Data Sets MDR_ID Section Number of records
MAGX_HR_1B MDR_MAG_HR 5101 6.1 0 – ~4,320,000
ASM_VFM_IC 5102 6.4 1
MAGX_LR_1B MDR_MAG_LR 5201 6.2 0 – 86,400
ASM_VFM_IC 5202 6.4 1
MAGX_CA_lB MDR_MAG_CA 5301 6.3 0 – 86,400
ASM_VFM_IC 5302 6.4 1
MAGXMAN_1B VFM_MAN_RP 5901 6.7 1
ASM_VFM_IC 5902 6.4 2
MAGXEUL_1B VFM_EUL_CA N/A 6.8 1
MF__EUL_PA N/A 6.9 1
ASMXAUX_1B MDR_ASMAUX 5401 6.5 0 – ~4,320,000
VFMXAUX_1B MDR_VFMAUX 5501 6.6 0 – ~4,320,000
EFIX_PL_1B MDR_EFI_PL 5601 6.10 0 – 172,800
LP_X_CA_1B LP__OFF_CA 6001 6.11 0 – 5
TIIX_CA_1B TII_FIT_CA 6101 6.12 1
GPSX_RO_1B MDR_GPS_RO N/A 6.15 0 – 8,640
GPSX_RN_1B MDR_GPS_RN N/A 6.16 0 – 12
GPSXNAV_1B MDR_NAVSP3 N/A 6.13 0 – 86,400
MODX_SC_1B MDR_MODSP3 N/A 6.13 0 – 86,400
STRXATT_1B MDR_SAT_AT 5701 6.14 0 – 86,400
ACCX_PR_1B MDR_ACC_PR 5801 6.17 0 – 86,400

Table 11: Level 1b Data Sets

X = A, B or C defining the satellite

Each Data Set is build of Data Set Records with fixed record lengths, except for the MDR_GPS_RO and MDR_GPS_RN (RINEX) Data Sets which have variable record lengths.

The MDR_ID column of Table 11 lists the Data Set Record identifier values of the corresponding Data Set.