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

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:

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]:

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.

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

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

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:

Table 5: ASMXAUX_1B and VFMXAUX _1B SPH - Specific Parts

The MAGX_CA_1B Product SPH shall contain the specific parts:

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:

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:

Table 8: STRXATT_1B SPH - Specific Part

The EFIX_LP_1B, EFIXLPI_1B and LP_X_CA_1B Product SPHs shall contain the specific Product Confidence part:

Table 9: EFIX_LP_1B SPH - Specific Part

The ACCX_PR_1B and SC_XDYN_1B Product SPH shall contain the specific Product Confidence part:

Table 10: ACCX_PR_1B and SC_XDYN_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.

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.