Update your GPS before April 6 or it might not work!

Older GPS and those that have not recently updated their firmware might not work properly after April 6, 2019.

GPS signals from satellites include a timestamp, needed in part to calculate one’s location, that stores the week number using ten binary bits. That means the week number can have 210 or 1,024 integer values, counting from zero to 1,023 in this case. Every 1,024 weeks, or roughly every 20 years, the counter rolls over from 1,023 to zero.

The first Saturday in April will mark the end of the 1,024th week, after which the counter will spill over from 1,023 to zero. The last time the week number overflowed like this was in 1999, nearly two decades on from the first epoch in January 1980.

You can see where this is going. If devices in use today are not designed or patched to handle this latest rollover, they will revert to an earlier year after that 1,024th week in April, causing attempts to calculate position to potentially fail. System and navigation data could even be corrupted, we’re warned.

Devices after 2010 should be all right, but it is advised to update the firmware to the latest version. Earlier devices might not fare so well.

The issue here is not so much handheld outdoor GPS units, but the GPS in smartphones as well as elsewhere. If you think a device you own uses GPS in any aspect, it is probably wise to update its firmware. The world is not going to end if you don’t, but you will guarantee that you will avoid some annoying inconvenience by doing so.

Hiding messages using fonts

A new computer technique has been developed that uses subtle changes to a document’s fonts to encode secret messages and data.

Using Columbia University’s FontCode system, however, users can hide messages within unrelated text via virtually-invisible changes to the displayed letters.

Developed by a team led by associate professor of computer science Changxi Zheng, FontCode works with commonly-used fonts such as Times Roman, Helvetica, and Calibri, plus it’s compatible with most word processing programs. Additionally, the hidden messages are retained even when the document is printed on paper or converted to a different file type.

The video at the link explains very nicely how this works. The technology has some excellent potentially positive applications, such as providing a method of finding out if an original document has been modified. It also carries with it a great potential for misuse because of its ability to hide information unobtrusively in a written document.