text: //=================== Filtering sources, an example ======================= 
  // Before running those charts, on the server:
  //   - enable connections 'aava-n2k.data' and 'Plaka log' in SignalK Dashboard, menu Server/Connections
  //   - disable all other connections
  //   - restart SignalK
  // Sources avalaible by path can be seen in Signal K Data Browser
  //   or by clicking 'Enumerate paths' from Stripcharts startup menu
  // Note: On real data such charts may help in calibrating some instruments
  
  const Speeds_per_source =
      { stripChartName: "Speed_per_source",
          timeWindow: 600,          // 10min
          avgInterval: 2,           // 2 sec
          x: { label: "min/sec ago", tickCount: 11 },
          y: { unit: "Knot" },
          paths: 
          [
              { path: "navigation.speedOverGround[Plaka log.II]", AVG: "SOG-Plaka" },
              { path: "navigation.speedOverGround[aava-n2k.data.160]", AVG: "SOG-aava" },
              { path: "navigation.speedThroughWater", AVG: "STW" }
          ]
      };
  
  const Speeds_ALL_sources = derivedFrom(Speeds_per_source,
      { stripChartName: "Speeds_ALL_sources",
          paths: 
          [
              { path: "navigation.speedOverGround", AVG: "SOG-all" },  // all sources averaged
              { path: "navigation.speedThroughWater", AVG: "STW" }
          ]
      }
  );
      
  const Directions_per_source = derivedFrom(Speeds_per_source,
      { stripChartName: "Directions_per_source",
          y: { unit: "Direction_Degree" },
          paths: 
          [
              { path: "navigation.courseOverGroundTrue[Plaka log.II]", AVG: "COG-Plaka" },
              { path: "navigation.courseOverGroundTrue[aava-n2k.data.160]", AVG: "COG-aava" },
              { path: "navigation.headingTrue", AVG: "HDG" }
          ]
  
      }
  );
  
  const Direction_ALL_sources = derivedFrom(Directions_per_source,
      { stripChartName: "Direction_ALL_sources",
          paths: 
          [
              { path: "navigation.courseOverGroundTrue", AVG: "COG" }, // all sources averaged
              { path: "navigation.headingTrue", AVG: "HDG" }
          ]
      }
  );
  
  // ===================== stripCharts set ============================
  // define stripChartsSpecs as a set of selectable stripCharts
  // identify the two charts that will display at startup (optional)
  
      const  stripChartsSpecs = {
          name: "Filtering sources",    // shows in tab title
          stripCharts: [
              Speeds_per_source,
              Speeds_ALL_sources,
              Directions_per_source,
              Direction_ALL_sources
          ],
          initialUpperView: Speeds_per_source,    // one of the stripCharts
          initialLowerView: Speeds_ALL_sources    // another one
  };
  
  // You may overide some options here ...
  
  