[time-nuts] Fw: [Off-Line] Thunderbolt & Lady Heather 48 hour precision survey

[WarrenS]

I may of not answered your question.

The answers is SORT of, Maybe, Sometimes, and could be that it resemble the 
horizon.
BUT
I've seen clear view all the way to near 0, still getting bad up around 20+ 
degrees
One case it was due to a near by pole reflecting signals.

The more typical case is there is some obstruction in one direction and then 
it is all a compromise to get rid of the obstructed signals as much as 
possible without EVER loosing all satellites.
A single weak poor satellite will cause the Tbolt to do Phase jumps.
The only thing worse is if it ever looses ALL satellites and goes into 
holdover.

The next test needed after setting the elevation to get rid of weak and poor 
signals, is to do another run and make sure that are always 2+ satellites in 
view using Tbolts Count plot.
Weak signals are bad, BUT they are far better than no signal.

ws

*****************

----- Original Message ----- 
From: "WarrenS" <warrensjmail-one at yahoo.com>
To: "Discussion of precise time and frequency measurement" 
<time-nuts at febo.com>
Sent: Saturday, November 27, 2010 9:40 AM
Subject: Re: [time-nuts] Thunderbolt & Lady Heather 48 hour precision survey


>
> Black means NO data available
> This can be due to several possible reasons,
>
> 1) the elevation mask setting, Tbolt does not report on anything below the 
> mask setting.
> 2) Run is not long enough.  Have not yet had a bird in that position yet.
> 3) no satellites ever in that position, like North when in the northern 
> hemisphere.
> 4) obstructions from things
>
> I thing what you are asking about, the answer is mostly 3 or 1
>
> The mask was set to 20 because of multipath and weak signals below 20 
> degrees
> One sign of Multipath is high ripple in the signal strength, best seen 
> using Tbolts "SAD Z"  command
>
> ws
>
> ***********************
>
> [time-nuts] Thunderbolt & Lady Heather 48 hour precision survey
> J. L. Trantham jltran at att.net
> Sat Nov 27 17:28:23 UTC 2010
>
> Warren,
>
> Just curious.  Does the 'black' background of your image resemble the
> horizon at your location?  Trees, buildings, towers, etc.?
>
> Joe
>
> -----Original Message-----
> From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] 
> On
> Behalf Of WarrenS
> Sent: Saturday, November 27, 2010 11:15 AM
> To: Discussion of precise time and frequency measurement
> Subject: Re: [time-nuts] Thunderbolt & Lady Heather 48 hour precision 
> survey
>
>
>
> Right, For best performance, in fix mode operation, for a Tbolt, you don't
> want to run at zero (or 5) degrees.
> This is just one test in a series of necessary test, if one wants to 
> improve
>
> their Tbolt to better than the Default settings.
> The zero degree mask is a temporary setting so that the Tbolt can do a 
> full
> antenna signal strength vs. position survey using Tbolts's "SAS" command.
> The purpose of which is to find the BEST elevation setting, which turns 
> out
> to be more like 15 to 35 deg for the typical Tbolt setups I've seen.
> Attached is a limited survey where the finial cutoff was set at 20 
> degrees.
> The cut off was set there because the full survey showed that in this case
> "BAD" things where starting to happen around 20 degrees
>
> ws
>