code: function AisPositionObj (ais) {
      this.devid= ais.mmsi;   // make a fake devid for device mmsi
      this.lat  = ais.lat;
      this.lon  = ais.lon;
      this.sog  = ais.sog; 
      this.cog  = ais.cog;
      this.alt  = 0;          // this is a boat it does not hick mountains!!! 
      this.date = new Date(); // use computer time 
  }
docs: small object to keep track of last position in ram