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Reference factor value 2.63

  • 1.  Reference factor value 2.63

    Posted 11-25-2022 11:07

    Hi all, my results after network adjustment is as shown above. What does it mean by reference factor of 2.63? Now how should I proceed further?

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    Shanker KC
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  • 2.  RE: Reference factor value 2.63

    Posted 11-25-2022 17:52
    Your a priori estimates of observations' errors in your network were too optimistic.

    Review the guidelines to processing control networks by DTMR QLD. They explain step by step how to preform adjustments in TBC.

    https://www.tmr.qld.gov.au/business-industry/Technical-standards-publications/Surveying-support-documents



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    Marian
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  • 3.  RE: Reference factor value 2.63

    Posted 11-26-2022 07:32
    Thank you @Marian Plucinski. I will catch you later.​

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    Shanker KC
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  • 4.  RE: Reference factor value 2.63

    Posted 11-27-2022 02:56

    Hi all, this is my adjustment settings. I set antenna height error 5mm and centering error 5mm. What should be the optimal error value for antenna height and centering purpose?
    and
    what does it mean by "Scale on Linear Error[s]: 1.960"?



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    Shanker KC
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  • 5.  RE: Reference factor value 2.63

    Posted 11-27-2022 14:08
    5mm accuracy for horizontal centering is a rather shabby work.

    I'd recommend 1-2mm for centering error and 2-3mm for antenna height error.

    Scale on linear error of 1.96 indicates that error were multiplied by 1.96 to bring them from 1-sigma 68% confidence level to 2-sigma 95% confidence level.

    I'd highly recommend reviewing the manual to which I posted the link. It's all explained there.

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    Marian
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  • 6.  RE: Reference factor value 2.63

    Posted 11-28-2022 11:19
    The a-priori error estimates, as shown above, really depend on the tools and procedures that go into the work. While 5mm centering error is much higher than I would have for most of our GNSS work, if we are using a standard prism pole at 2.5m high, then maybe it is appropriate. We check our bubbles all the time and store them carefully. I used fixed height tripods for static GNSS work, and those are good to a couple mm for centering and even better for height.

    1.96 is 2 sigma (95% confidence) for the error reporting. It is a pretty standard level of confidence for our work.

    I suspect that you would benefit from some proper training. While this can seem like a push button type thing, a professional shouldn't just black-box it.

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    Dave Olander
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  • 7.  RE: Reference factor value 2.63

    Posted 11-29-2022 13:28
    Great source of information all in one document! Thank you for sharing.

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    Sean Lahann, PLS
    Phoenix, Arizona
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  • 8.  RE: Reference factor value 2.63

    Posted 11-28-2022 17:14
    I highly recommend you check out TBC help videos, because with a value that high you probably have some measurements that are causing the high value.  Fine tuning a network adjustment and possibly disabling poor measurements is something that needs to be done.  Going blind you could have kind of ugly poorly adjustment data.

    Power Hour video vault:
    https://community.trimble.com/browse/blogs/blogviewer?BlogKey=a533ca86-f306-4c04-ba43-64e1ae88d776

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    Robert Hoy
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