[time-nuts] Thunderbolt setup

[lists at lazygranch.com]

Well other than moving to Kansas, I doubt I will ever see the horizon. 

The "official" timing antennas are designed not to see well at the horizon. I use a marine GPS which does see the horizon, but filter those birds out. 

-----Original Message-----
From: "Bob Camp" <lists at rtty.us>
Date: Wed, 16 Mar 2011 12:55:27 
To: <lists at lazygranch.com>; 'Discussion of precise time and frequency measurement'<time-nuts at febo.com>
Subject: RE: [time-nuts] Thunderbolt setup

Hi

If you can see to the horizon, you can likely get reasonable timing off of
sats to 10 to 20 degrees off the horizon. If you can only see to 45 degrees
above the horizon, then you can likely get good timing off sats that are 55
to 65 degrees or higher. In both cases you can track further, the data just
gets worse. 

Just how close you can get will always depend on the type of obstruction and
how much multipath it generates (if any).  If you are in a deep canyon
things are different than if there's one big pine tree due south. 

Bob

-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of lists at lazygranch.com
Sent: Wednesday, March 16, 2011 12:36 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Thunderbolt setup

My point is the Tbolt software is set up to ignore birds on the horizon. It
is a parameter you can set.  So I don't follow how seeing the horizon is
very important. 


------Original Message------
From: Bob Camp
To: lists at lazygranch.com
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Thunderbolt setup
Sent: Mar 16, 2011 4:51 AM

Hi

If you only have one sat to look at, horizon view is worse than overhead.
With multiple sats you want them spaced out over the sky to get a benefit
from triangulation.

More TBolt opinions (there are lots of us and we all have them ...)

The wonderful thing about a TBolt is that it can use foam core TV satellite
coax. Since 75 ohms is lower loss than 50 ohm (all else being constant) you
can get away with quite a bit of the stuff. F connectors are easy to do
wrong, so get some good ones and a proper crimp tool.  Most antennas are TNC
or N, so you will need an adapter. Again - get a good one. 

Keeping the antenna away from traffic is your first goal. Up in the air is
one way to do that, far from the house is another way. Last choice would be
near the dinner table. Good view of the sky down to about 20 degrees off the
horizon is ok. A view to 10 degrees is slightly better. Don't worry a lot
about a view towards the north pole if you are in the northern hemisphere. 

Run the unit constantly. The OCXO will settle down that way. The holdover
training will work best that way. The power required is pretty modest.
Mounting the unit in some sort of enclosure is an excellent idea simply to
minimize accidents. The power connector needs some protection from bumps and
snags. 

Where ever you mount the unit, consider that they tend to multiply. You may
soon have three or even more than twenty. 

So much fun.

Bob


On Mar 16, 2011, at 5:15 AM, lists at lazygranch.com wrote:

> I thought for timing a view of the horizon was bad. 
> 
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