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

[Darrell Robinson]

I am not an expert.

My guess is that at least some of the difference that you see in your
altitude is from the propagation delay in the cable between your antenna and
the GPS module.

Guessing still further, I would think that the position as reported would be
some distance immediately below the antenna.  How long is your cable?

If the antenna is stationary, you could move the GPS module to any position
within the sphere allowed by your length of cable, and the reported position
would stay the same.



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
> ---------------------
>
>
>
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