As a replacement please take a look at Sail_Instrument
AvNav more-nmea Plugin
===========================
This project provides a plugin for AvNav to calculate additional (hopefully) useful data .
Basically this plugin uses the AvNav Plugin Interface.
It calculates the Magnetic Variation at the actual position based on the World Magnetic Model 2020 of NOAA
If there are "APPARENT" Winddata in the NMEA input stream it calculates: ·
| Value | Format | Storename | Description |
|---|---|---|---|
| MagVar | +/- 180 [°] | gps.MagVar | Magnetic Variation |
| AWA | +/- 180 [°] | gps.AWA | Apparent WindAngle |
| AWD | 0…360 [°] | gps.AWD | Apparent WindDirection |
| AWS | 0..∞ [m/s] | gps.AWS | Apparent WindSpeed |
| TWA | +/- 180 [°] | gps.TWA | True WindAngle |
| TWD | 0…360 [°] | gps.TWD | True WindDirection |
| TWS | 0..∞ [m/s] | gps.TWS | True WindSpeed |
·
In case of "TRUE" Winddata no calculation is done, because True winddata are not very likely on boats!
(If there is interest in calculation of Apparent Wind-Data from TRUE, please leave a message in Issues)
In adition the plugin listens for incoming NMEA records regarding course and speed.
If NMEA records with course data are received ($HDM or $HDG or $VHW) it calculates:
| Value | Format | Storename | Description |
|---|---|---|---|
| HDGm | 0…360 [°] | gps.HDGm | Heading magnetic |
| HDGt | 0…360 [°] | gps.HDGt | Heading true |
in case of $VHW records it will also create
| Value | Format | Storename | Description |
|---|---|---|---|
| STW | 0..∞ [m/s] | gps.STW | Speed through water |
NEW:
Since Release 20210517 the Plugin is able to create the following NMEA records: $MWD, $MWV, $HDT, $HDM and $HDG. These messages are available i.e. on the SocketWriter Ports.
They will be transmitted only, if the necessary signals are available and if there is no record with the same name in the NMEA input data stream.
One can explicitly declare which records to be sent by using the FILTER_NMEA_OUT Parameter (i.e. “$HDT,$MWV" to transmit only these two).
If the "Filter_NMEA_OUT" is empty, all records are transmitted.
One can avoid to transmit a specific record by adding its name as inverse (i.e. “^$HDT”) to the "Filter_NMEA_OUT".
A special case are the records $HDG, $MWV and $VHW because these messages have different meanings depending on their message content:
$HDG, $MVW can be either TRUE oder RELATIVE. In this case the plugin delivers the opposite TRUE oder RELATIVE Message, even if there is already a message with the same name in the input stream.
Based on $VHW the plugin also creates the corresponding $HDT or $HDM and $HDG messages, if they are not already in the input stream.
If case of feeding back the avnav-nmea records to signalk, you should add the sourceName Parameter (i.e. "more_nmea") to the blackList of the AVNSocketWriter that is used in signalk for receiving data from avnav in the avnav_server.xml to avoid creating a loop.
The Plugin can be configured in the avnav-Server.xml with the following parmeters:
| Name | Default Value | Description |
|---|---|---|
| WMM_FILE | "WMM2020.COF” | The WMM-Coefficent-File in the Plugin Directory |
| WMM_PERIOD | "10" | Intervall (sec) to calculate Variation |
| NMEAPeriod | “1” | Intervall (sec) to transmit new NMEA-records |
| computePeriod | "0.5” | Intervall (sec) to read NMEA-records |
| FILTER_NMEA_OUT | “” | Filter for transmitted new NMEA-records |
| sourceName | “more_nmea” | source name to be set for the generated records |
Please report any Errors to Issues
License: MIT
Installation
You can use the plugin in 2 different ways.
- Download the source code as a zip and unpack it into a directory /home/pi/avnav/data/plugins/more-nmea.
If the directory does not exist just create it. On an normal linux system (not raspberry pi) the directory will be /home/(user)/avnav/plugins/more-nmea.
In this case the name of the plugin will be user-more-nmea. So you can modify the files and adapt them to your needs.
- Download the package provided in the releases section or build your own package using buildPackage.sh (requires a linux machine with docker installed). Install the package using the command
sudo dpkg -i avnav-more-nmea-plugin...._all.deb
User App
The plugin registers no User App
Configuration (Server)
No configuration necessary
Widget
The plugin provides no specific Widget.
One can use the default widget from avnav to visualize the data by selecting the appropriate gps... message.
Formatter
To display values in a proper unit the necessary formatters are included in the default widget.
Implementation Details
**Take care for NMEA200 Sources: **
The Signalk-Plugin "sk-to-nmea0183" has some bugs:
-
$VHW : see SignalK/signalk-to-nmea0183#63
-
$HDG : Swapped Deviation and Variation see SignalK/signalk-to-nmea0183#71
The sentences from canboat are ok, as far as tested!
HDGt (Heading True) is calculated from HDGm (Heading magnetic from $HDM or $HDG or $VHW) taking into account the magnetic variation if no True Heading Data is received.
Receiving True Heading overwrites calculated Data!
If magnetic variation is received (by $HDG) inside the "WMM_PERIOD" -time this value is taken into account.
Package Building
For a simple package building NFPM is used and started in a docker container (use buildPkg.sh). In the package.yaml the properties of the packge can be set.
Additionally a GitHub workflow has been set up to create a release and build a package whenever you push to the release branch.
So when you fork this repository you can create a package even without a local environment. To trigger a package build at GitHub after forking just create a release branch and push this.