The computer can decode the PIES\u2019 language into values of measured parameters (Credit: D. Kieke).<\/figcaption><\/figure><\/div>\n\n\n\nBut why would I sit there with headphones on and listen to the sounds of the PIES during our research cruise when we are supposed to recover them? It is because these devices come with a special feature: You can actually \u201ctalk\u201d to them. By lowering a hydrophone – basically a waterproof microphone and speaker – into the water you can send acoustic commands to the device and listen to its answers. The PIES understands different commands, including CLEAR (\u201cstop whatever you are doing and tell me if you can hear me\u201d), TELEMETRY (\u201ctell me what you have recorded since the last data readout\u201d) and RELEASE (\u201cdetach from your bottom weight and ascend to the ocean surface\u201d). The TELEMETRY command is used to receive a compressed form of the recorded data via acoustic signals, similar to morse code, before recovering the instrument. In the unusual case that something goes wrong during recovery and you unfortunately lose the instrument, at least you have the data. When the PIES receives the TELEMETRY command it starts sending acoustic signals at different frequencies and intervals which can be translated by a computer into the different parameters measured by the instrument. When the data transmission via acoustic telemetry is finished, the PIES can be recovered. The recovery is mostly done during the night since the PIES are equipped with a bright flashing light that can be seen best during the night.<\/p>\n\n\n\n
It is close to midnight now and I am sitting in the lab with headphones on. The acoustic telemetry of our last PIES for this research cruise has finished successfully and the data have been safely stored on a hard disk. I have sent the RELEASE command to the PIES, and the device has confirmed that it has detached from its bottom weight. Since it is now buoyant it ascends to the surface while constantly pinging. From the traveltime of these pings to the hydrophone of the ship I can infer the depth to which the device has ascended until now. I can see that the device is close to surfacing, and thus almost everyone who is awake right now is standing on the bridge looking out for a flashing light in the darkness of the night.<\/p>\n\n\n\n
TO BE CONTINUED<\/p>\n","protected":false},"excerpt":{"rendered":"
This is post 2\/3 in a series on our experiences and tasks as ArcTrain PhD students during the research cruise M164 (GPF 19-1-105) in summer 2020 in the subpolar North Atlantic. Click here to see part 1\/3 and here to see part 3\/3. A research cruise offers the great opportunity to escape your usual office […]<\/p>\n","protected":false},"author":48,"featured_media":2881,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1,19,22,20],"tags":[],"coauthors":[54],"translation":{"provider":"WPGlobus","version":"2.12.2","language":"en","enabled_languages":["en","de","fr","ru"],"languages":{"en":{"title":true,"content":true,"excerpt":false},"de":{"title":true,"content":true,"excerpt":false},"fr":{"title":false,"content":false,"excerpt":false},"ru":{"title":false,"content":false,"excerpt":false}}},"post_mailing_queue_ids":[],"_links":{"self":[{"href":"https:\/\/arctrain.de\/wp-json\/wp\/v2\/posts\/2873"}],"collection":[{"href":"https:\/\/arctrain.de\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/arctrain.de\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/arctrain.de\/wp-json\/wp\/v2\/users\/48"}],"replies":[{"embeddable":true,"href":"https:\/\/arctrain.de\/wp-json\/wp\/v2\/comments?post=2873"}],"version-history":[{"count":39,"href":"https:\/\/arctrain.de\/wp-json\/wp\/v2\/posts\/2873\/revisions"}],"predecessor-version":[{"id":3037,"href":"https:\/\/arctrain.de\/wp-json\/wp\/v2\/posts\/2873\/revisions\/3037"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/arctrain.de\/wp-json\/wp\/v2\/media\/2881"}],"wp:attachment":[{"href":"https:\/\/arctrain.de\/wp-json\/wp\/v2\/media?parent=2873"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/arctrain.de\/wp-json\/wp\/v2\/categories?post=2873"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/arctrain.de\/wp-json\/wp\/v2\/tags?post=2873"},{"taxonomy":"author","embeddable":true,"href":"https:\/\/arctrain.de\/wp-json\/wp\/v2\/coauthors?post=2873"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}