Category Archives: Nautical Information Systems

Calculating distance from Lat & Lon coordinates using Python & Pandas

Given a GPS log file structured as follows (column separators omitted for clarity): Speed Latitud Longitud Time 2019-01-07 06:15:27 0 59.649582 17.721365 2019-01-07 06:16:28 0 59.649583 17.721372 2019-01-07 06:17:28 0 59.649583 17.721370 2019-01-07 06:18:28 0 59.649583 17.721372 2019-01-07 06:19:29 0 … Continue reading

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Python & Pandas to map gps coordinates to known locations

Assume you have a gps log file, with time and position (Lat,Lon in columns 9,10) info, like: 2018.12.12 00:41:20;0;0;0;0;0;1;0;25.8;59.348978;17.969643;0;0; 2018.12.12 01:41:21;0;0;0;0;0;1;0;25.7;59.348962;17.969627;0;0; 2018.12.12 02:41:21;0;0;0;0;0;1;0;25.7;59.349;17.969688;0;0; 2018.12.12 03:41:21;0;0;0;0;0;1;0;25.7;59.349;17.96966;0;0; 2018.12.12 04:41:22;0;0;0;0;0;1;0;25.6;59.349007;17.969618;0;0; 2018.12.12 04:48:50;0;0;0;0;1;1;1;25.2;59.349007;17.969635;0;0; 2018.12.12 04:49:51;0;0.001;0;0;1;1;1;28.3;59.349;17.969642;0;0; Assume further that you’d like to map each of … Continue reading

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An area preserving map projection

area preserving map projection

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Capturing NMEA sentences over WiFi using Python

In order to figure out how the NMEA-WiFi Gateway deals with clients, e.g. if it expects any “handshake” or any other communication setup protocol, I decided to write a simulator mimicing the gateway, and then using iRegatta 2 from Zifago … Continue reading

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Parsing NMEA 0183 sentences in Python

My skipper has recently bought an NMEA wifi gateway, which means that the NMEA messages from the various onboard instruments on his yacht are broadcasted on the yacht’s wifi network. This makes it very easy to grab the NMEA messages, … Continue reading

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Wind Speed Distribution – is it Normal…?

As a sailor, I’ve become obsessed by wind. Trying to understand its behavior has kept me busy for decades, and still, I can’t claim I fully understand wind behavior. Anyways, one of the things I’ve wondered is whether wind is … Continue reading

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Map Projections using Python & Basemap

The numerous external libraries available for Python continue impressing me, in scope, numbers and ease of use.  A couple of hours ago I googled for chartographic tools for Python, and found the Basemap-library, an add-on to Matplotlib. For whatever reason, … Continue reading

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Great Circle Navigation

The shortest distance between two points is a straight line, right…? Nope, not on the surface of a sphere, like our earth. On a sphere, the shortest distance between two points is a Great Circle.  Let’s say you are a … Continue reading

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Radar Plotting & Trial Manouver on iPad/iPhone

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