[time-nuts] TBolt self survey

Raj vu2zap at gmail.com
Thu Feb 11 00:56:42 UTC 2010


My GPS reading is about 850 +- 1
The "official" height ASL = 920

This calculator gives me ~936

So what should I use ?

Thanks
Raj

At 10-02-10, you wrote:
>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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-- 
Raj, VU2ZAP
Bangalore, India. 




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