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Maybe the US overturned the patent, but did other countries overturn theirs? I thought AIS was originally a Swedish invention.
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-------- Original message --------<br>
From: Heikki Hannikainen <hessu@hes.iki.fi> <br>
Date:09/05/2014 23:48 (GMT-05:00) <br>
To: TAPR APRS Mailing List <aprssig@tapr.org> <br>
Cc: <br>
Subject: Re: [aprssig] Digital two-way Radio communication in emergency situations
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<div class="PlainText">On Fri, 5 Sep 2014, andrewemt wrote:<br>
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> team, but runs into trouble as soon as an uncoordinated outsider comes on frequency. The marine<br>
> AIS system has a solution, but it's patent-encumbered.<br>
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By the way:<br>
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The United States Patent and Trademark Office (USPTO) canceled all claims <br>
in the original patent on March 30, 2010.<br>
<br>
USPTO ex-parte reexamination certificate (7428th), issued on March 30, 2010<br>
<br>
(Source: wikipedia, but I think I saw/read the USPTO documents back in <br>
2010, it was news then)<br>
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> Also, the fixed equal-size timeslot<br>
> scheme only works with stations sending about the same amount and size of traffic (in your<br>
> case, only trackers transmit, not mixed station types).<br>
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AIS supports a few different sizes, the shorter position packets are sent <br>
often, and every now and then the station reserves a larger slot for <br>
sending it's full name and/or other information.<br>
<br>
- Hessu<br>
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