The Imagenex 881A Imaging Rotary Sonar devices area multi-frequency digital scanning sonars.
http://www.imagenex.com/Products/881A/881A_Imaging/881a_imaging.html
http://www.imagenex.com/Products/881A/881A_Profiling/881a_profiling.html
The data products for Imagenex 881A sonars are described here. Currently, there are two types of Imagenex Rotary 881A Sonar scans supported: Sector (also known as Imaging) and Profile. Sector scans represent a horizontal rotation of the sonar, like a radar, and profile describe a vertical rotation, like a radar turned on it's edge or a freewheel. The data products for both are the same, except that imaging plots have a direction arrow to indicate true north (see the device's metadata for the heading), while the profiling plots will contain a mention that a tilt angle offset was applied to orient them vertically (see the device details page (example) -> additional attributes -> sonarProfileTiltAngle). In either case, the plots will also note if there's no heading or tilt angle available (for the profiling plots without the tilt angle offset, the seabed echo may appear upside-down reversed and/or off-horizontal - this will be improved as the tilt angles are updated). Also note that the tilt angle offset is applied for all Imagenex Rotary Sonar data products for profiling sonars, when it is defined. In general, these data products contain the same information that is available through the manufacturer's software; primarily backscatter amplitude, range, head angle and time, plus various metadata.
Oceans 3.0 API filter: dataProductCode=IRSD
Imagenex sector and profile scans are available in 6 formats: MAT, AVI video (no sound), PDF and PNG static images, animated GIF, 81A (proprietary Imagenex raw format) and TXT text files.
Data: A structure array containing the following fields:
Oceans 3.0 API filter: extension=mat
The root imaging product is the PNG file. Users will see the usual location and device header at the top, the text in the lower left to indicates the range and scan number, start and stop times, and the graph in the bottom-right depicts the pressure fluctuations over the course of the 24 hours from a collocated CTD (if available). A PNG search will provide multiple, static images one per scan or profile. The PDF product contains multiple scans on multiple pages in vector format (infinite resolution). The GIF product collates PNG scans for each day. The AVI product, like the PDF product, contains as many images / scans as possible with the limit determine by file size (approximately 100 MB for the PDF, up to 1 GB or 4096 scans for the AVI). Both the GIF and AVI formats move through the scan images every 0.5 seconds, see example GIF above.
If the imaging plots do not have a heading, a small comment will appear instead of the North arrow. If the profiling plots do not have an orientation, a small note will also appear.
Oceans 3.0 API filter: extension={png,pdf,avi,gif}
81A files are the manufacturer’s native data format and readable by the software program win881A.exe (downloadable from the Imagenex website http://www.imagenex.com/Downloads/downloads.html).
These files are the same as the log file products, with the 'Z' stripped out of the dates and driver and non-hex lines removed. Plus, the sonarProfileTiltAngle is applied to orient the data vertically. Imagenex TXT files are also available with the 'hourly' or scan separated option. Sample output:
20111216T000000.012> fe 44 10 05 00 00 43 00 12 01 10 00 78 03 10 00 00 00 00 19 08 06 00 00 05 a5 fd 20111216T000001.014> fe 44 10 05 00 00 43 00 12 01 10 00 78 03 10 00 00 00 00 19 08 06 00 00 05 a5 fd 20111216T000002.018> fe 44 10 05 00 00 43 00 12 01 10 00 78 03 10 00 00 00 00 19 08 06 00 00 05 a5 fd 20111216T000003.018> fe 44 10 05 00 00 43 00 12 01 10 00 78 03 10 00 00 00 00 19 08 06 00 00 05 a5 fd |
Oceans 3.0 API filter: extension=txt
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