MWV.js

'use strict'

/**
 * Copyright 2016 Signal K and Fabian Tollenaar <fabian@signalk.org>.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

const debug = require('debug')('signalk-parser-nmea0183/MWV')
const utils = require('@signalk/nmea0183-utilities')

function convertToWindAngle(angle) {
  const numAngle = utils.float(angle) % 360
  if (numAngle > 180 && numAngle <= 360) {
    return numAngle - 360
  }
  return numAngle
}

module.exports = function(input) {
  const { id, sentence, parts, tags } = input

  if(!parts[4] || parts[4].toUpperCase() !== 'A') {
    return null
  }

  let wsu = parts[3].toUpperCase()

  if (wsu === 'K') {
    wsu = 'kph';
  } else if (wsu === 'N') {
    wsu = 'knots';
  } else {
    wsu = 'ms';
  }

  const angle = convertToWindAngle(parts[0])
  const speed = utils.transform(parts[2], wsu, 'ms')
  const valueType = parts[1].toUpperCase() == 'R' ? 'Apparent' : 'True';
  const angleType = parts[1].toUpperCase() == 'R' ? 'Apparent' : 'TrueWater';

  const delta = {
    updates: [
      {
        source: tags.source,
        timestamp: tags.timestamp,
        values: [
          {
            path: 'environment.wind.speed' + valueType,
            value: speed
          },
          {
            path: 'environment.wind.angle' + angleType,
            value: utils.transform(angle, 'deg', 'rad')
          }
        ]
      }
    ],
  }

  return delta
}