# Obtaining depth from the ROV

**URL:** <https://discuss.bluerobotics.com/t/obtaining-depth-from-the-rov/4566>\
**Category:** Blue Robotics Software\
**Created:** [March 7, 2019, 12:06pm UTC](https://discuss.bluerobotics.com/t/obtaining-depth-from-the-rov/4566 "2019-03-07T12:06:26Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![BigAl](https://avatars.discourse-cdn.com/v4/letter/b/ea666f/32.png) [@BigAl](https://discuss.bluerobotics.com/u/BigAl)\
**Post date:** [March 7, 2019, 12:06pm UTC](https://discuss.bluerobotics.com/t/obtaining-depth-from-the-rov/4566/1 "2019-03-07T12:06:26Z")

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How do I obtain the pressure sensor reading using MavLink ?

I have tried MAVLINK\_MSG\_ID\_SCALED\_PRESSURE"but the values don’t make any sense.  
pressDiff = -10.7hPa  
absPress = 508.1hPA

I haven’t looked at RAW\_PRESSURE yet but is that message I should be using.

I am building a towed system (i.e. a sidescan, ROV without thrusters) as a cheap system for collecting imagery over reefs for mapping using 3D reconstruction. I feed a calculated position (as a psuedo USBL position) for the sub using a fixed layback but would like to feed an accurate depth for the sub from the pressure sensor.

Regards,

Alan

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**Author:** ![patrickelectric](https://sea1.discourse-cdn.com/flex019/user_avatar/discuss.bluerobotics.com/patrickelectric/32/2162_2.png) [@patrickelectric](https://discuss.bluerobotics.com/u/patrickelectric)\
**Post date:** [March 7, 2019, 5:00pm UTC](https://discuss.bluerobotics.com/t/obtaining-depth-from-the-rov/4566/2 "2019-03-07T17:00:04Z")

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Hi Alan,

Did you check **SCALED\_PRESSURE2**?  
**SCALED\_PRESSURE** is from the pixhawk internal barometer and not from the outside one.  
This is my output with the ROV and the second pressure scaled message.

 ![image](https://us1.discourse-cdn.com/flex019/uploads/bluerobotics/original/2X/1/1a8e7a87ff6a3731ecdbf2f646ca8245bc2e7608.png)

If you want depth, check [VFR\_HUD](https://mavlink.io/en/messages/common.html#VFR_HUD) message.

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**Author:** ![BigAl](https://avatars.discourse-cdn.com/v4/letter/b/ea666f/32.png) [@BigAl](https://discuss.bluerobotics.com/u/BigAl)\
**Post date:** [March 9, 2019, 9:31am UTC](https://discuss.bluerobotics.com/t/obtaining-depth-from-the-rov/4566/3 "2019-03-09T09:31:56Z")

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Thank you this was exactly what I was after

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**Author:** ![patrickelectric](https://sea1.discourse-cdn.com/flex019/user_avatar/discuss.bluerobotics.com/patrickelectric/32/2162_2.png) [@patrickelectric](https://discuss.bluerobotics.com/u/patrickelectric)\
**Post date:** [July 20, 2020, 2:05pm UTC](https://discuss.bluerobotics.com/t/obtaining-depth-from-the-rov/4566/4 "2020-07-20T14:05:38Z")

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