Differences

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--- sensors [2019/10/21 15:09] – [Level 2 Headline] nikolal
+++ sensors [2022/09/19 11:34] (current) – external edit 127.0.0.1
@@ Line 1: / Line 1: @@
 ====== Sensors ======
-To receive information from the fish tags, the Otter is equipped with an Thelma Biotel [[https://www.thelmabiotel.com/receivers/tbr-700-rt/|TBR 700 RT]]. This communicates with the RaspberryPi through RS-485 on the StratoPI CAN board.
+The hydrophone used on the Otter is a [[https://www.thelmabiotel.com/receivers/tbr-700-rt/|TBR 700 RT]] from Thelma Biotel. This provides detections of acoustic
-===== Level 2 Headline =====
+tag, as well as measurements taken in the hydrophone.
+Depending on the software version ordered from the manufacturer, the hydrophone can detect tags transmitting
+on 63-77 kHz. Typically, lower frequencies are only suitable for larger tags, while higher frequencies are mostly
+used in smaller tags. It detects tags that transmit using using Differential Pulse Position Modulation (DPPM), and
+can use different protocols to give meaning to the time delays between pulses.
+The communication with the controlling computer is through a RS-485 interface, delivering messages in
+a NMEA 0183 inspired format. Bluetooth communication is also present, but
+not used for real-time operations like those the Otter target. Instead, it can be used to download lists of
+detections after a mission has been performed.
+Power is supplied through the same cable as the RS-485 uses, but in a separate lead. It accepts a DC voltage of 5-12V, so 5V is used in the Otter because it was available and unused by the other components. Battery power is also possible,
+but not used in the Otter project.
+===== Making custom IMC messages =====
   * [[http://uavlab.itk.ntnu.no/wiki/doku.php?id=software:imc|IMC wiki uavlab]](Needs NTNU VPN login)