GPS not updating Alpha 5 Clock-Solved!

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  • #20272
    ka7gzr
    Participant

    I completed my Alpha 5 this weekend. I have v2 and loaded the GPS program. All works perfectly except the time stability with the GPS interface. When the GPS is enabled the Alpha 5 drifts about 2 seconds an hour when compared to WWV. The GPS has a good lock and updates the Alpha 5 initially but drifts rapidly after that. I have tried it with the GPS disabled and it is much more stable with the Chrono Dot. The GPS locks quickly and never loses Lock. Any Ideas?

    • This topic was modified 2 years, 4 months ago by Windell Oskay.
    #21512
    Windell Oskay
    Keymaster

    To the extent that you do have a lock, it is likely not actually drifting. That means that you are apparently having periods of a sizeable fraction of an hour when you do not have lock. We haven’t had this problem with our example running the code, so it’s likely not a firmware bug. 


    The basic problem– and the reason that Alpha Clock Five does not come with the GPS module as a default option — is that it’s hard to guarantee a GPS lock, especially indoors. You might consider moving it elsewhere or adding an external antenna to the GPS module.
    #21513
    ka7gzr
    Participant

    Thanks for the response Windell.

    The GPS module has a red LED that flashes @ a 2 second rate when acquiring and at a 12 second rate when locked. It is always locked. I have about 25 GPS receivers in my home (some using the exact same GPS module) and none of them ever drop out. They are associated with my 25 Nixie clocks. So I don’t believe its a GPS signal strength issue. 

    What is strange is the drift rate is much higher with the GPS then the basic clock. Would it make sense even if I was losing lock with the GPS that the drift rate would be higher?

    I suppose it would be a function of how the code is implemented…

     

     

     

    #21514
    Windell Oskay
    Keymaster

    The author thought that using the Chronodot was not important when the GPS was used… and that is part of the  explanation. 

    Does the Alpha Clock Five indicate that it is staying locked? It indicates unlocked condition with the alternating colon separators. 
    #21515
    ka7gzr
    Participant

    I didn’t know that. I will look closely tonight. I wonder if the Chronodot should be removed when the GPS is enabled? I looked closely at the GPS illustrations and could see a Chronodot in place.

    #21516
    ka7gzr
    Participant

    Windell,

    The colons are steady with the GPS enabled.

    Please tell me your settings so I can duplicate them. Maybe it’s an issue with the settings…

    Jim

    #21517
    Windell Oskay
    Keymaster

    We have GPS on and DST on… I’m not sure that there are other settings that are relevant. 

    #21518
    ka7gzr
    Participant

    I have been in contact with the author. I was able to resolve the issue. I’m not quite sure what got it working. He gave me alot more details about the display indications when it is updating or not. At any rate all is well!

    Jim

    #21519
    Windell Oskay
    Keymaster

    Okay great– glad to hear it. If you do figure out what made the difference, it would be nice to know for people who have the same problem in the future. :)

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