[time-nuts] TBolt self survey

Arnold Tibus Arnold.Tibus at gmx.de
Wed Feb 10 14:07:41 UTC 2010


Try to find your correct height here:
http://sps.unavco.org/geoid/

If you put in your correct coordinates without any input for the elevation, 
you will get theorthometric height, which is the GPS ellipsoidal height 
minus geoid height. That is the amount you need to subtract from 
your Thunderbolt GPS height in order to get your local geodetic height 
(WGS84). 

Filling in the Thunderbolt GPS height you will get the 'real' height 
for your antenna...

Some explanations:
http://www.unavco.org/edu_outreach/tutorial/geoidcorr.html

On my location I have always to reduce the GPS height by 46.623 m.
Good luck with TB and the Lady Heather,

Arnold, DK2WT



On Wed, 10 Feb 2010 14:20:36 +0100, EB4APL wrote:

>Raj,

>Ask them about ellipsoidal and orthometric heights, or the local 
>difference between the geoid and the WGS84 ellipsoid.  Also your long 
>and lat may change depending of the Geodetic Reference System chosen.  
>By default GPS receivers use WGS84 and ellipsoidal height.

>73 de Ignacio, EB4APL

>--------------------------------------------------------------------------------------
>Raj wrote:
>> Thanks Stan,
>>
>> That worked, I did not see the  control menu properly!
>>
>> I set the co-ords to 0 0 0 and started survey. The Tbolt found the Lat long withing a few minutes and only the altitude is about 70 M below the official figure for my place. I live a a few hundred meters from Bangalore center and I am at the same height.. must check with the survey dept. down the road!!
>>
>> 73
>> Raj vu2zap
>>
>>
>> At 10-02-10, you wrote:
>>   
>>> Hello Raj,
>>>
>>> using the trimble T'boltMON software:
>>>
>>> Start with a "factory reset" in the control menu
>>>
>>> follow previous guidance of enabling the "save position" capability,
>>>
>>> Then to restart a survey
>>>
>>> go to the control menu (on left),
>>> select "restart self survey"
>>>
>>>
>>> In lady Heather V3.0 beta of 21 Jan '10 ( available from the KE5FX website):
>>> keyboard enter a "s", for survey
>>> then "s" for a standard survey,
>>> use the default of 2000 samples,  for a start
>>> Then "enter"
>>>
>>> Time for me to go to bed.
>>>
>>> Please advise of progress.
>>>
>>> Stan,  W1LE
>>>
>>>
>>> Raj wrote:
>>>     
>>>> Thanks Stan,
>>>>
>>>> I did that but I can't where to "start the survey" in TBolt. In lady heather there
>>>> is a key for it.
>>>>
>>>> At 09-02-10, you wrote:
>>>>  
>>>>       
>>>>> Hello Raj,
>>>>>
>>>>> that location is probably where the coordinates were last saved. or there abouts....
>>>>> Or those are the default factory settings from memory,
>>>>> and new coordinates were never saved.
>>>>>
>>>>> redo the survey and save the results.
>>>>>
>>>>> using T'boltMON V2.60 on a PC:
>>>>>
>>>>> go to menu "set up",  then "self survey",   click on the "save position flag"
>>>>> then "set survey",
>>>>> then "save segment",
>>>>> then "close"
>>>>>
>>>>> redo the survey and afterwards verify the local coordinates were saved.
>>>>>
>>>>> Lady Heather (software) can also be utilzed for these functions.
>>>>>
>>>>> Any problems, please advise.
>>>>>
>>>>> Stan, W1LE
>>>>>
>>>>>
>>>>>
>>>>> Raj wrote:
>>>>>    
>>>>>         
>>>>>>       Can someone point me to info that would clarify why my Tbolt's self survey puts my house (AFAIK ~920M ASL, 13N 77.35E) in the Pacific ocean, south of Vancouver and west of Seattle and about 10 meters under water. I am doing something wrong for sure!
>>>>>>
>>>>>>       My sons iPhone gives me right co-ordinates but it's way off the altitude.
>>>>>>       
>>>>>> Regards
>>>>>>           






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