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Messages - malcolmh

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1
Full UTC date/time data is to be found in Base station reports, of which there are a few in the sample. Ship position reports only give the seconds after the UTC minute in their timestamps. To determine the full time, it will be necessary to fast forward to the Base Station report to get the date, hour & minute for the preceding messages.

2
The @ character is not terminator, but rather a fill character to pad out fixed-length string fields. Decoding software would treat the first @ as a terminator, but encodng software must fill out fixed-length strings with trailing @ characters

3
From the standard (1):

"Character strings are presented left to right most significant bit first. All unused characters should be
represented by the @ symbol, and they should be placed at the end of the string."

(1) http://www.itu.int/dms_pubrec/itu-r/rec/m/R-REC-M.1371-5-201402-I!!PDF-E.pdf

4
Software development / Re: Message 5 encoding - where to split?
« on: 26 January, 2017, 02:06:09 pm »
Messages 4 & 11 both contain full UTC date & time.

5
Software development / Re: Message 5 encoding - where to split?
« on: 05 January, 2017, 10:51:22 am »
There is no rule for this in the standard, but the usual convention is to split the message on a six-bit boundary, such that the fill bit field is zero on all but the last sentence.

6
AIS Dispatcher / Re: Sending UDP data to data.aishub.net
« on: 17 October, 2016, 10:00:42 am »
Yes. That is how aisdispatcher sends the data. You can check that your data is being received OK by inspecting the statistics entry for your station.

7
General Discussion / Brighton
« on: 13 January, 2015, 11:43:17 am »
What exactly is the Brighton station? It seems to upload data from everywhere except Brighton - Solent, Dover Strait, Humber, Tees, German Bight & even China!

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