[time-nuts] Timing performance of servers

lists at lazygranch.com lists at lazygranch.com
Thu Oct 25 14:02:54 EDT 2012


The GPS seeing the horizon isn't required. Those satellites are filtered out by software. The timing GPSs are designed to be less sensitive to the horizon.


-----Original Message-----
From: Chris Albertson <albertson.chris at gmail.com>
Sender: time-nuts-bounces at febo.com
Date: Thu, 25 Oct 2012 10:04:43 
To: Discussion of precise time and frequency measurement<time-nuts at febo.com>
Reply-To: Discussion of precise time and frequency measurement
	<time-nuts at febo.com>
Subject: Re: [time-nuts] Timing performance of servers

On Thu, Oct 25, 2012 at 9:44 AM, Sarah White <kuzetsa at gmail.com> wrote:

> Regardless of if I run linux vs bsd vs windows (will be testing multiple
> configurations of each, and doing writeups over the next few years as I
> test more and learn) I'll need a good external antenna for the new GPS
> I'm going to run.
>
> Anyone think I can get by with anything cheaper than a symmetricom
> 58532a antenna? I can probably get one (used) for less than $50 on ebay,
> but I'd really prefer to source something more entry-level for closer to
> $5 or $10 if possible. Any suggestions?

Chris Albertson
Redondo Beach, California

Location matters a LOT more than the brand of antenna.

In an ideal world a GPS antenna needs to see all the way to the
horizon in all directions AND it needs to be far way from reflective
objects that can cause "multi path".   Some times moving a foot or
some is enough for an improvement.

You will notice that the best timing mode antenna come inside
enclosures made to shed water and snow.  They are pointy or round on
top.   You don't need this feature if the antenna is looking out a
window.  In fact the small patch type antenna might be able to be
place close to a window and get a better view of the sky.

All that said.  These are good and not expensive.  ebay #270881742870
I have one of these on a mast and the cable fits inside the pipe/mast.
the patch antenna is cheaper see #290739284641

One thing to watch is the kind of connectors.  You don't want to have
to use a chain of adaptors, N to F to BNC.   Those can cost $5 each
and certinly do not help the signal.  For outdoors I like "N" type as
they are 100% water proof.   Some types of "F" are too but not all of
them.

Watch that you get a 5V volt antenna (unless you really want a 3.5
volt type) and get a co-axial type cable.  Some have odd-ball
multi-pin cables

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