7K to S7k

The Pydro macro Hypack 7k to s7k attempts to do two separate steps. The first is to convert the Hypack 7K file to a Reson s7k file, and the second is to convert the navigation and attitude stored in the corresponding Hypack HSX file into the s7k format and append it to the end of the converted file. The HSX file is paired by looking for a file with the same name as the 7K file but with the HSX extension.

The Hypack 7K file contains Reson s7k data records as would be recorded by the Reson 7K center with the addition of two sets of headers. Reson adds a network header to data sent via TCP or UDP to allow for the reassembly of records too large to fit over the network. Hypack does not remove these headers or reassemble large packets when the records are received. In addition Hypack adds a simple four byte header that describes the size of the total packet being written to disk. The macro reads the 4 byte Hypack header and the Reson network header to determine where the s7k record is and write it to disk unmolested. Large snippet records can sometimes end up with a Hypack header internal to the Reson data structure, thus careful tracking of the data read and then written to disk must the accomplished to successfully write an unmangled s7k file. If the Hypack header or the Reson network header is not correct, the scripts attempts to recover by looking for a sync pattern found at the beginning of the Reson s7k record, and then searching backward for the Hypack header. Sometimes data can be lost in the process of recovery.

Since the Hypack 7K file contains only the Reson multibeam records the converted s7k file may be of limited use without the corresponding navigation and attitude. If an HSX file can be found, the script converts the Hypack navigation and attitude into Reson 1003, 1012 and 1013 records and appends them to the previously converted file. No attempt is made to convert the projected position into a geographic position as is usually found in the s7k file. The script specifically asks for the UTM zone so that this information can be stored in the s7k data packets for use down stream.

Resources

Online Resources:

• Hydrographic Specs and Deliverables (HSSD)
• Field Procedures Manual (FPM)
• Hydroforum
• HydrOffice

Contact

If you find errors in the documentation or want to contribute, you are encouraged to email the following personnel emails @NOAA.GOV

• barry.gallagher
• jack.riley
• chen.zhang
• eric.younkin