Monday, January 19, 2015

FAQ - Why Does Your Map Show My QTH Incorrectly?

Every week I get a couple of e-mails asking "How come you map my QTH in Missouri (or Ontario, or central instead of eastern Russia).  Here's the answer - 

When we go to plot a dot on the map for a station that has been spotted, we query QRZ.com.  Most of the time that returns a location we can use, but occasionally it doesn't.  In that case the website defaults to an arbitrary location for the center of the country as determined by the prefix.  For performance reasons (imagine a busy contest weekend) and to avoid wearing out our welcome at QRZ.com, we cache station locations for a week or so before doing another lookup.  If a station is active, its location will generally be corrected by the next query after the cache has expired.

13 comments:

  1. Pete,
    How about an RBN database into which (via username & password) a user would enter his own location.

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  2. I've been following this problem almost daily for the last several months. In my case, my position is plotted wrongly almost exactly twice as often as it is correct. Rather than "Most of the time it returns a correct location" (paraphrasing the top of this FAQ) in my case it's "One third of the time it returns a correct location."
    Since RBN has to cache locations anyway, I would have thought some algorithm like "If the lookup fails, reuse the existing cache location" would be better than "If the lookup fails, use the arbitrary center-of-country location."
    Having said all that, this is a very minor issue. I think the RBN system is incredible. Lots of praise and thanks to all involved in inventing and maintaining it.

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    1. You do seem to be a bit of an outlier. I can't begin to explain why your QTH should be giving us so much trouble. How often are you spotted, would you say? More than once a week?

      Your suggestion about reusing the previous cache location, or redoing the lookup, or something of the sort does seem preferable to just going for the center of the country. When Felipe returns from traveling in Portugal before too long, I will ask him to put a solution to this at the top of his to-do-list

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    2. Now you're talking, Pete.
      I can't imagine, though, why QRZ.com location data would vary.
      BTW, I'm typically spotted more than one hundred times per week, usually accompanied by incorrect dot location at center-of-population for USA.

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    3. Homer, I'd take your comments a lot more seriously if you signed your real name and callsign.

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    4. Thanks, Pete. I'm typically spotted much more than a hundred times per week. Not quite every day, but most days.
      Thanks again, 73, Darrel aa7fv.

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    5. Pete: Any news on whether Felipe may have been able to look into a solution yet? I continue to use RBN almost daily, and my position plotted on the map still appears to be wrong somewhat more often that it's correct.
      I still can't get over what a great system the RBN is.
      Thanks, 73, Darrel aa7fv,

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  3. This comment has been removed by the author.

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  4. For the past year or so, RBN now has very accurate map position of my QTH.
    Thanks, you guys!

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  5. Ted Roycraft - W2ZKJanuary 9, 2017 at 10:39 AM

    I'm sure this question must have been asked before so I apologize in advance but I have not been able to find an answer. Is there a way, when setting up filters, to indicate NOT, e.g. Continent: NOT NA or CQ Zone: NOT 5? Maybe I'm overlooking something but I think the ability to do that would be very helpful.
    Thanks! Ted, W2ZK

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  6. A simple question...can you explain the red and green dots on the map? Thank you.

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  7. Sure - the green dots represent RBN nodes - receivers that heard a station. The red dots represent the stations heard, i.e. the spots.

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  8. Hi & thanks too for such a great system. Regarding location, is there a way to temporarily register different QTH with RBN or QRZ.com(perhaps with an expiration)? I spend 2 to 3 mos/yr at another location. Also for SoTA and portable outings.
    Thanks, Bill KE3YW

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