The Pinnacle Origin Story

The challenges were set in early discussions. Build an Acoustic Doppler Current Profiler (ADCP) that profiles to 1000 m but make it smaller than existing systems. Also, make sure the raw data is preserved and accessible in every foreseeable circumstance. The obvious starting point to profile to 1000 m is to lower the frequency, which means increasing the diameter of the transducer. Since the diameter quickly becomes quite large, a phased array transducer is preferred because it generates all beams from a single aperture. The first red flag: if Pinnacle is to be a phased array system that will sometimes be deployed looking up from depth, then the traditional thirty-degree Janus array generated by traditional phased array ADCPs results in a significant sidelobe exclusion zone near the surface. The rule of thumb for thirty-degree angles is to exclude the last 15% of the range, and the top 150 m of the ocean is usually the most “interesting”. This leads to the first truly new aspect of the Pinnacle: it is a phased array ADCP with a twenty-degree Janus angle (Patent Pending) to reduce that exclusion zone to 6%. This is a significant technological advance, involving a completely different phasing approach. Pinnacle further reduces its transducer size by reducing the number of elements. The Pinnacle phased array transducer obtaining a 2000 m depth rating is also new. The traditional method for depth rating a phased array is oil filling, but that is messy and involves a lot of work to allow for differing thermal expansion of the oil relative to the rest of the array. Pinnacle has a different filler that greatly simplifies both the assembly process and end design. All of these innovations will be discussed in detail. Data have increasingly become the most valuable result of any deployment - often far more valuable than the actual instruments involved in obtaining them. In a long autonomous deployment, gigabytes of raw data are generated and there is often no way to know the data quality until after the instrument is recovered at the end of the deployment. This leads to the next truly innovative aspect of Pinnacle. It has dual data storage - separate recorders in the direct read and self-contained modules to which all raw data are written simultaneously (Patent Pending). The recorder in the direct-read module is accessible via Ethernet for download, but the recorder in the self-contained module is easily removable when the module is opened for a battery swap. On recovery, the instrument's software immediately compares the two recorders and informs the user if there are differences between the recorders. It also provides a summary of the quality of the data. If all appears good, the removable memory can be scanned while the batteries are swapped. The data are protected by being separately recorded simultaneously to two recorders in separate housings. To allow for catastrophic damage the removable memory has its own “black-box” pressure case of last resort. Lastly we present some data gathered from a prototype unit offshore of San Diego, CA.