APRS Article 15

January-February 2002

 

News and Views

By Jeff Robbins

VE3JTR (Voice Call)

VA3JTR (APRS Call)

EMAIL: va3jtr@rac.ca

WEB:  http://www.qsl.net/va3jtr

 

Happy New Year to you!

 

Wow, 2002.  We certainly have been moving along since Y2K.  Anyone remember the hype and worry over the Y2K bug?  Looking back, there sure wasn’t so much to worry about.  However, as a software person, I can appreciate the potential that existed before the big push to update software to four digit years.

 

What is less known, is that we in the APRS world had a Y2K-like event of our own.  Towards the end of August 1999, the GPS world was bracing for the W1K (Week 1024) bug.  What was that all about?

 

In the GPS world, your unit keeps a tally on the number of weeks that have elapsed since a specific point in time.  According to the United States Navy, the GPS Week Number count began shortly before midnight on the evening of 05 January 1980 / morning of 06 January 1980.  Since that time, the count has been incremented by 1 each week, and this data is broadcast as part of the GPS messaging.  The GPS Week Number field rolls over after 1023.  This means that at the completion of week 1023, the GPS Week Number rolled over to 0000 at midnight of the evening of 21 August 1999 / morning of 22 August 1999. This time is in UTC, and precisely occurred at 23:59:47 UTC.  So what was the potential problem for GPS users?  Well, your unit may have decided that the date was January 6th, 1980.  Did that really matter?  After all, who cares if the GPS date is wrong?  The potential problem that existed, is that the GPS needs an accurate time AND date in order to determine what satellites should be visible in the sky, and make position calculations accordingly.  So if the date is incorrect, the particular combination of satellites in the sky would not be correct, and you calculated position could be hundreds of kilometers off, if the GPS is able to come up with a position at all.

 

Like Y2K, this caused some worry in the rest of the world.  The South Korean government, for example, sent out an alert to help prevent accidents in the air and across the sea by vessels relying on GPS.  Australian authorities warned travelers to avoid taking small planes or boats in remote areas of the globe because of the GPS glitch.  The U.S. Coast Guard urged boaters and other civilian users of the Global Positioning System to play it safe and make sure alternative navigation methods were available. The U.S. Military also announced that older GPS receivers could have started malfunctioning even sooner than expected as the Air Force began the process of uploading software updates to the GPS satellites.  These updates were not directly intended to correct the W1K bug, but rather were major updates of time and position data.  The new data may have confused some older receivers, as the time information will assume the weekend clock rollover had already taken affect.

 

This really was a big deal!  But you don’t know the half of it yet.  Most seasoned users of the GPS are unaware, as the author was, that the GPS system is not just used for traditional positioning purposes.  A less well-known but extremely important use of GPS involves using the precise time signals from the system to coordinate telecommunications and computer networks.  These GPS clocks are used in banking for money transfers and bank time locks, among other things.  They are used for time keeping in certain scientific experiments.  It would appear that the potential for world wide chaos existed some 19 weeks before Y2K!

 

So how did the GPS world fare?  The United States military took the stance that this W1K ‘bug’ was design intent, so it was up to the manufacturers of GPS equipment to ensure that GPS units could operate with new software in the satellites.  And they did.  So unless you were using a well aged GPS in August 1999, most likely you were completely unaware what was going on inside the plastic case, and your position continued to be as accurate as before.  I didn’t notice any extra million or so dollars end up in my bank account (best case scenario, of course) so I guess the telecommunications world was prepared as well.  I am sure that GPS manufacturers will not be caught again by this, but in any case keep April 6 / 7, 2019 in mind.  That is the next time the counter will roll over to 0000!

 

Advertisement time!  Well, not really, but I have been asked to get the word out, so here I go.

 

Get ready for the Southern Ontario/Western New York APRS Symposium!  A day of APRS Information and Demonstrations awaits those that will be attending.  Yup, yours truly is planning to be there as well.  The planned venue is the Best Western Brant Park Inn and Conference Centre in Brantford, Ontario.  Your hosts will be Ken Dobson, VA3DDB in Brantford, ON, Martin Girouard, VA3DVR from St. Thomas, ON and Tom Domonkos, VE3FCK from Niagara Falls, ON.  Ken’s is a name you all have heard about in this column before, and he is really positioning himself as a leader in the APRS community.  All interested Hams are encouraged to attend as we plan to discuss a standardized province wide digi-path system for Ontario. Your input is valued and appreciated.  We will also be discussing setting up an Elmer mentoring system for the province to help new and existing APRS hams to get started or to assist in problems they encounter.  But time is limited, as the date has been set for Saturday January 12th.  Doors open at 9:00 for coffee and social time, followed by a full day of seminars and group discussions.  Now if you are feeling a bit hungry half way through, don’t worry, lunch is provided!  For all the details, look for the Coming Events announcement, elsewhere in this issue.

 

At the time of writing, Ken was working on getting a website up and running, but an address was not yet available.  I will, however, provide a link from my webpage http://www.qsl.net/va3jtr

 

So, unless I see you in person at the APRS Symposium, I’ll be seeing you, ON THE MAP!