[time-nuts] Another Trimble Tbolt question....

[phil]

From: "Darrell Robinson" <darrell at shaw.ca>
To: "Discussion of precise time and frequency measurement" 
<time-nuts at febo.com>
Sent: Sunday, March 30, 2008 3:19 AM
Subject: Re: [time-nuts] Another Trimble Tbolt question....


>
> More guessing.  I wonder if the altitude you see is from the difference
> between Mean Sea Level and Height Above Ellipsoid?
>
> This document has a map on page 7 -
> http://www.avionicswest.com/PDFiles/alt2.pdf
>
> Still no expert
>
> Darrell
>
>
>
> ----- Original Message ----- 
> From: "Michael Baker" <mpb45 at clanbaker.org>
> To: <time-nuts at febo.com>
> Sent: Saturday, March 29, 2008 5:49 AM
> Subject: [time-nuts] Another Trimble Tbolt question....
>
>
>> Hello, All--
>>
>> Thanks to the collective savvy of this list and the
>> patient assistance of Ken Winterling <wa2lbi> I was
>> finally able to get my Tbolt to stop requiring me
>> to configure the COM-4 channel every time I ran
>> the monitoring software.
>>
>> So-- I had such good luck with that question, I'm
>> going to pester the group with one more Tbolt question:
>>
>> In the "Position" area of the Tbolt monitoring display
>> my altitude is given as 1.4 meters.   The USGS topo map
>> and a recent survey both say that the ground level
>> at my house is 84 feet above MSL.  The antenna for the
>> T-bolt is on the top of my house 19 feet above the ground.
>>
>> If I open SETUP / POSITION and "SET ACCURATE POSITION"
>> to, say....: 28 meters and enter that value, the indicated
>> altitude changes to 28 meters, but the next day or so,
>> I always find that it has reverted to 1.4 meters.
>>
>> Admittedly, having a (relatively) accurate altitude
>> display is of minor importance to me since my primary
>> reason for having the Tbolt is for a decent 10MHz reference.
>>
>> However, as a matter of principle it would be nice to
>> have the altitude display be a little closer!
>>
>> Any suggestions as to how to get the Tbolt to
>> display a more correct altitude?
>>
>> Thanks!
>>
>> Mike Baker
>> WA4HFR
>> Micanopy, FL


For what it's worth, I have two of these units and they are horrible on 
altitude but otherwise seem to be ok.
Just a thought !
Phil