- #Hypack cable counter how to#
- #Hypack cable counter drivers#
- #Hypack cable counter update#
Altitude sensor - some side-scan sonars provide the fish altitude above the bottom. You must also configure the mobile associated with the fish to use that device as depth sensor. #Hypack cable counter drivers#
You have to interface this device using any of the available echosounder drivers (try using the generic one).
Depth sensor - the fish is fitted with a pressure transducer that sends out directly the fish depth. Shallow fish- the fish depth is always 0 (this is more of a raft than a fish). The driver setup box provides four options for determining the fish depth: It can be seen from these formulas that once user enters a cable length (or we get a reading from the cable counter) we can calculate the layback if we know the tow fish depth. corrected_cable is calculated from the cable length using the following formula:Ĭorrected_cable = catenary_factor x cable_length. Z_offset is the height of the A-frame above water level and it is positive when the A-frame is above the water (it is cumbersome to place the A-frame under water) It is positive when A-frame is astern of reference point. Y_offset is the distance from boat's reference point to the A-frame. With these assumptions in place the magic layback formula is: This way, things are a lot simpler for everybody and the only drawback is that the fish might not be where you see it on the screen. We have to make these assumptions because otherwise you would have to provide a lot of information regarding the fish and the cable (stuff like drag coefficients, specific weight, etc) and we would have to solve some complicated differential equations. Water depth under the boat and under the fish is the same (you are traveling over an unusually flat bottom). the tow fish is linked using a pole rather than a cable) There is a straight line from boat to fish (i.e. In calculating the fish position we make the following assumptions that we know are wrong: Of course it can also be a "dumb" fish without any sensors installed. The fish can have either a pressure transducer that outputs the depth of the fish or an altitude transducer that provides the height of the fish above the bottom. #Hypack cable counter update#
The cable counter driver can be used either with automatic cable counter devices (currently it supports two formats: Dynapar and MD Totco) or in manual mode (in which case the operator has to update the cable length).
#Hypack cable counter how to#
This note briefly describes how to use the cable counter driver to calculate an approximated position for a tow fish.
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