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EncDotNet.S100.Nmea

EncDotNet.S100.Nmea is a minimal NMEA 0183 reader: it checks sentences, decodes the wind, temperature, pressure, heading and motion sentences, and reads lines from a stream, a recording, TCP or UDP. It has no dependency beyond EncDotNet.S100.Core (for Angle, Speed and GeoPosition), so the NMEA weather source and, later, an own-ship NMEA driver can share it.

Not for navigation.

Install

This package isn't published to NuGet. Reference the project directly:

<ProjectReference Include="path/to/src/EncDotNet.S100.Nmea/EncDotNet.S100.Nmea.csproj" />

Example: read wind from a multiplexer

using EncDotNet.S100.Nmea;

var input = new NmeaUdpLineSource(port: 10110);
await foreach (var line in input.ReadLinesAsync(cancellationToken))
{
    if (!NmeaSentence.TryParse(line, out var sentence, out var error))
        continue; // error says why: ChecksumMismatch, MissingChecksum, ...

    if (NmeaDecoder.TryDecode(sentence, out var message) && message is MwvSentence { IsValid: true } mwv)
        Console.WriteLine($"{mwv.Reference} wind {mwv.Angle?.TotalDegrees}° {mwv.Speed?.TotalKnots:0.0} kn");
}

Main entry points

Type Purpose
NmeaSentence One sentence: talker, formatter and fields. TryParse checks the *hh checksum, and rejects a line without one by default, since a cut-off sentence has none. It skips an NMEA 4 tag block, keeps the last sentence when a cut-off one is glued to it, and reports why a line was rejected (NmeaParseError). Format builds a sentence with its checksum.
NmeaDecoder Decodes by formatter, whatever the talker: MWV (wind angle and speed, relative or true), MWD (true and magnetic wind direction and speed), MTW (water temperature), XDR (transducers), HDT, HDG (with deviation and variation), VHW (heading and speed through the water), RMC (position, time, speed and course over the ground, variation) and VTG. Speeds are converted from knots, m/s, km/h or statute mph.
XdrSentence All of an XDR's measurements, plus AirTemperatureCelsius and PressureHectopascals: the outside air temperature and barometric pressure, picked by type, unit, range and a name that doesn't mark them as an engine's, a tank's or a cabin's.
TrueWind True wind from apparent wind, over the ground (heading, SOG and COG) or through the water (heading and speed through water).
INmeaLineSource Where lines come from. NmeaStreamLineSource (any stream, such as a serial port's), NmeaReplayFile (a recording, optionally paced and looped), NmeaUdpLineSource and NmeaTcpLineSource (reconnects). Each enumeration opens the input and closes it when it ends.

True wind: over the ground or through the water

TrueWind.OverGround uses the speed and course over the ground: it gives the wind a buoy or a forecast reports. TrueWind.ThroughWater uses the speed through the water along the heading: the sailor's true wind, which differs from the ground wind by the current. Both need the heading, since the apparent angle is measured from the bow. Neither corrects for mast motion, upwash or leeway.

See also

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