DDSsmb_read

Description

DDSsmb_read is a C program designed to convert raw Mesotech DDS (Digital Data Stream) SMB (Sonar Message Block) files, which typically contain raw element sonar data, into the Ocean Mapping Group (OMG) data format. In addition to the primary sonar data, it extracts and processes associated navigation and attitude information, outputting these into separate OMG-compatible files for further processing and analysis within the OMG ecosystem.

Usage 

DDSsmb_read [OPTIONS] -DDSsmb <filename(s)> -out <prefix>

Arguments

Option Description Default / Example
-v Enables verbose output, providing more detailed status messages during execution.  
-debug Activates debug messages, useful for troubleshooting and understanding internal processes.  
-pie Flag to indicate the creation of PIE (Post-Interp Echosounder) data.  
-dumpTA Flag to dump TA (Transducer Array) data.  
-interp Activates interpolation of beams, enhancing data quality.  
-pixel <value> Sets the pixel size for processed data.  
-maxdepth <value> Defines the maximum depth of interest for filtering or processing.  
-mindepth <value> Defines the minimum depth of interest for filtering or processing.  
-left_across <value> Specifies the left across-track range.  
-right_across <value> Specifies the right across-track range.  
-dB_range <min_dB> <max_dB> Sets the decibel range for packing data, likely for intensity values.  
-ping_start <value> Specifies a starting ping number for processing.  
-ping_end <value> Specifies an ending ping number for processing.  
-time_start <Y JD H M S> Defines a start time window (Year, Julian Day, Hour, Minute, Second) to filter data.  
-time_end <Y JD H M S> Defines an end time window (Year, Julian Day, Hour, Minute, Second) to filter data.  
-pack_samp <value> Sets a packing sample value.  
-DDSsmb <filename(s)> Required. Specifies one or more input Mesotech DDS SMB raw data files. data.smb
-out <prefix> Required. Defines the prefix for all generated output files. output_survey

Output Files

  • <prefix>.merged: Main merged data output.
  • <prefix>.merged.ss_data: Sidescan-like data.
  • <prefix>.merged.16_data: 16-bit data.
  • <prefix>.merged.ph_data: Phase data.
  • <prefix>.merged.ph16_data: 16-bit phase data.
  • <prefix>.orientation: Attitude data in OMG format.
  • <prefix>.nav: Navigation data in OMG format.

How It Works

  1. Command-line Argument Parsing: Provides extensive command-line options to control the conversion process, offering flexibility in data selection and output.
  2. File Handling and I/O: Manages the opening of input .smb files and a suite of output files, ensuring data can be written in various formats. Iterates through each specified input .smb file, reading its content.
  3. SMB Data Extraction and Parsing: Uses jSMB_get_next_tuple_header (an external function, likely defined in Mesotech_SMB.h or a related library) to sequentially parse the input SMB file. This function extracts SMB_Tuple_Header (smb_head) and SMB_Tuple_Footer (smb_foot) structures, along with the raw data payload (tdata) for each data block. Identifies different types of data telegrams within the SMB stream based on smb_head.DataType (e.g., 0x1008 for PMB profile solutions, 0x2001 for 16-bit amplitude and phase images).
  4. Time-based Filtering: If a time window is specified via -time_start and -time_end, the program checks each ping’s ping_time and skips processing for pings that fall outside this window.
  5. Output Data Generation:
    • Navigation Output (write_out_M3_nav): This function takes ping time, latitude, and longitude, and formats them into an jcu_nav_rec structure, which is then written to the OMG-compatible .nav file using nav_write. It incorporates a mechanism to prevent writing redundant navigation records if only_redundant is set.
    • Attitude Output (write_out_M3_attitude): This function extracts roll, pitch, heading, and heave data. It constructs an OMG_HDCS_summary_attitude header for the .orientation file upon the first record and then writes individual OMG_HDCS_attitude records using OMG_HDCS_write_attitude.
    • While other output files (.merged, .merged.ss_data, etc.) are opened, the specific logic for writing to these files based on the parsed SMB data types is not fully elaborated in the provided code excerpt, implying it resides within the SMB data type parsing blocks.
  6. Memory Management: Allocates a large tdata buffer (10MB) for reading raw SMB data and ensures it is freed before program exit.
  7. Error and Usage Reporting: Utilizes error(), warning(), and usage() functions (presumably from support.h) to provide informative messages for critical errors, non-critical issues, and command-line argument misuse, respectively.

Dependencies

  • support.h: Provides general utility functions for command-line parsing (strtoint, strtodbl), error handling (error, warning, check_error), and string manipulation (mem_strappend, mem_stripext).
  • stdtime.h: Offers functions for converting and formatting time data (stdtime_from_jul_day, stdtime_nicetime).
  • OMG_HDCS_jversion.h: Defines structures and functions specific to the OMG Hydrographic Data Collection System (HDCS) format, including OMG_HDCS_summary_attitude, OMG_HDCS_attitude, OMG_HDCS_dump_att_summary, OMG_HDCS_write_attitude, and OMG_HDCS_fileID_tag.
  • jcu_nav.h: Provides data structures (jcu_nav_rec) and functions (nav_write) for handling navigation data in a specific format.
  • Mesotech_SMB.h: Crucial for defining the structures of Mesotech SMB data (SMB_Tuple_Header, SMB_Tuple_Footer) and the function jSMB_get_next_tuple_header used for parsing these proprietary files.

Notes

The primary purpose of DDSsmb_read.c is to serve as a vital data ingest tool for Mesotech DDS SMB sonar data. By converting this proprietary format into the standardized OMG format, it enables seamless integration of Mesotech data into the broader OMG processing, visualization, and analysis workflows. The program’s filtering capabilities (by ping number or time) and flexible output options make it a versatile utility for hydrographic data management and quality control.