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Speed through water and True wind (signal K)
#1
I am working on rebuild and setup new system OP 2.1 on RPI4

I want to check as much as possible on the desk at home, before replace one system by another on the boat.


Now I have an issue with STW and True Wind information.


Goal: make sure STW and True Wind information correctly transmitted converted from signalK to NMEA and shown in OpenCPN.
Current state: Neither True wind or STW are not shown.


What I am doing:
To be clear, most sensors IMU,Apparent Wind,Pypilot,GPS are real and connected to RPi but no DEPTH and STW
STW value I simulate by "Signal K delta simulator"  and send value 1..1.2  to navigation.speedThroughWater.
Should it be in m/s? Should it be just number?

I can see in SignalK Data Browser: navigation.speedThroughWater 1.33295
I setup in "Convert Signal K to NMEA0183" plugin  VWT, VHW, MWV apparent and True, sentence to generate.

What the problem:
STW and true wind is not displayed on OpenCPN dashboard
VHW, VHT,and MWV true messages ate not observable in NMEA debug output from 10110 port



Data Browser output:

environment.mode
"day"

09/04 18:34:53
derived-data
environment.sun
"day"

09/04 18:34:53
derived-data
environment.wind.angleApparent
0.0914552528253848
rad
09/04 18:35:24
Pypilot NMEA 0183.AP
environment.wind.angleTrueGround
3.141592653589793
rad
09/04 18:35:24
derived-data
environment.wind.speedApparent
0
m/s
09/04 18:35:24
Pypilot NMEA 0183.AP
environment.wind.speedOverGround
0.9105668973436141
m/s
09/04 18:35:24
derived-data
navigation.attitude
{
 "roll": -0.064524824221,
 "pitch": -0.48260100474300005,
 "yaw": null
}

09/04 18:35:23
OpenPlotter.I2C.pypilot
navigation.courseOverGroundTrue
6.069033409345622
rad
09/04 18:35:24
gps.GP
navigation.datetime
"2020-09-04T22:35:24.000Z"

09/04 18:35:24
gps.GP
navigation.gnss.antennaAltitude
97
m
09/04 18:35:24
gps.GP
navigation.gnss.differentialAge
0
s
09/04 18:35:24
gps.GP
navigation.gnss.differentialReference
0

09/04 18:35:24
gps.GP
navigation.gnss.geoidalSeparation
0

09/04 18:35:24
gps.GP
navigation.gnss.horizontalDilution
2

09/04 18:35:24
gps.GP
navigation.gnss.methodQuality
"GNSS Fix"

09/04 18:35:24
gps.GP
navigation.gnss.satellites
4

09/04 18:35:24
gps.GP
navigation.headingMagnetic
3.9326456846616424
rad
09/04 18:35:23
Pypilot NMEA 0183.AP
navigation.magneticVariation
0
rad
09/04 18:35:24
gps.GP
navigation.magneticVariationAgeOfService
1599258924
s
09/04 18:35:24
gps.GP
navigation.position
{
 "longitude": -81.67766,
 "latitude": 33.53333333333333
}

09/04 18:35:24
gps.GP
navigation.speedOverGround
0.5864668152382598
m/s
09/04 18:35:24
gps.GP
navigation.speedThroughWater
1.0278599999999998
m/s
09/04 18:35:24
simulator.0
notifications.server.newVersion
{
 "state": "alert",
 "method": [],
 "message": "A new version (1.33.0) of the server is available"
}

09/04 18:30:52
signalk-serve
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#2
Each conversion needs certain input values to be available, see

https://github.com/SignalK/signalk-to-nm...js#L16-L18
https://github.com/SignalK/signalk-to-nm...VWT.js#L15
https://github.com/SignalK/signalk-to-nm...WVR.js#L25
https://github.com/SignalK/signalk-to-nm...MWVT.js#L7

make sure you have those Signal K paths active.
Reply
#3
(2020-09-05, 06:32 PM)tkurki Wrote: Each conversion needs certain input values to be available, see

https://github.com/SignalK/signalk-to-nm...js#L16-L18
https://github.com/SignalK/signalk-to-nm...VWT.js#L15
https://github.com/SignalK/signalk-to-nm...WVR.js#L25
https://github.com/SignalK/signalk-to-nm...MWVT.js#L7

make sure you have those Signal K paths active.

HI,

bumping this rather old threat since I have the same problem.

I get data from a canbus (wind as speed instrument) and want to get it into opencpn. I do not have Magnetic variation or headingTrue in my stream, only speed through water. How can I get the stw into opencpn then?
I would like to use it in the tactics app, which seems to use the nmea0183 stream? At least I do not see any data there when I use a signalK connection only.
AWA and AWS work fine, so do watertemp and depth, all via the nmea converter.

Any tips?
Reply
#4
(2022-04-29, 07:10 PM)FabianT Wrote: HI,

bumping this rather old threat since I have the same problem.

I get data from a canbus (wind as speed instrument) and want to get it into opencpn. I do not have Magnetic variation or headingTrue in my stream, only speed through water. How can I get the stw into opencpn then?
I would like to use it in the tactics app, which seems to use the nmea0183 stream? At least I do not see any data there when I use a signalK connection only.
AWA and AWS work fine, so do watertemp and depth, all via the nmea converter.

Any tips?

I don't use the SignalK in OpenCPN, opting for the TCP/IP connection to SignalK, as I find it works better for me and I get STW with it. Simply change the connection from SignalK/port 3000 to TCP/port 10110 and you should bet getting all the available NMEA0183 conversions direct from SignalK instead of asking OpenCPN to do them. The only thing I've found that is missing from TCP is engine data, which is available in the SK connection. If I need that data, then I put a second connection to SK/3000 with a lower priority.
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