The satellites use helix antennas.

John  WA4WDL

--------------------------------------------------
From: "Azelio Boriani" <azelio.bori...@screen.it>
Sent: Saturday, January 07, 2012 11:29 AM
To: "Discussion of precise time and frequency measurement" <time-nuts@febo.com>
Subject: Re: [time-nuts] Getting my Rockwell D200 GPS to work

Just take care that GPS signal is right-hand circularly polarized. For
those interested in building GPS antennae I recommend the QFH-type antenna: quite complex but it is the same antenna actually used to transmit from the
birds.

On Sat, Jan 7, 2012 at 5:02 PM, David <davidwh...@gmail.com> wrote:

I have done the same thing with an amplified patch antenna facing out
the window.

I wonder in this case if making a rough 1/4 wave antenna out of a very
short feedline would be enough for a cheap outdoor sanity check.

On Sat, 7 Jan 2012 14:21:09 +0000, shali...@gmail.com wrote:

>I test all my GPS receivers with a hockey puck type antenna attached to
the wall in my hamshack, which is upstairs, but under the ceiling and the
roof and I have never had one fail to lock within reasonable time. With
this setup, Thunderbolts occasionally go on holdover, but never for very
long.
>
>Of course, when I plug them in the external Symmetricom antenna, they
typically see more satellites and don't go into holdover.
>
>I am in Northwest Florida, so probably at a lower latitude than most of
you, so the same setup farther north may not work as well.
>
>Didier KO4BB
>
>Sent from my BlackBerry Wireless thingy while I do other things...
>
>-----Original Message-----
>From: Azelio Boriani <azelio.bori...@screen.it>
>Sender: time-nuts-boun...@febo.com
>Date: Sat, 7 Jan 2012 02:00:21
>To: Discussion of precise time and frequency measurement<
time-nuts@febo.com>
>Reply-To: Discussion of precise time and frequency measurement
>       <time-nuts@febo.com>
>Subject: Re: [time-nuts] Getting my Rockwell D200 GPS to work
>
>Absolutely yes, the antenna must see the sky, not the ceiling. Even very
>sensitive GPS receivers must have a good view of the sky for the first
fix,
>then you can bring the antenna indoor. You can try positioning the >antenna >very near a window for just a test but better a good view. The car roof >is
>okay but you must wait several minutes (12 minutes at most) to let the
>receiver download the almanac.
>
>On Sat, Jan 7, 2012 at 1:54 AM, Don Lewis <dlewis6...@austin.rr.com>
wrote:
>
>> Maybe I didn't take positioning seriously.
>>
>> The antenna is currently on a shelf above my workbench, ....there is a
>> ceiling and an upstairs above it. Then the roof.
>>
>> Is it very critical to be outside in order to 'see' the sky?
>>
>> I did take it out once and set the antenna on my car roof, ....but
still no
>> satellites.
>>
>>
>> -Don
>>
>> From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] >> On
>> Behalf Of bownes
>> Sent: Friday, January 06, 2012 6:49 PM
>> To: Discussion of precise time and frequency measurement
>> Cc: Discussion of precise time and frequency measurement
>> Subject: Re: [time-nuts] Getting my Rockwell D200 GPS to work
>>
>> Step one...is the antenna in a location where it can see they sky?
>>
>> Sorry if it is a stupid question but you already said it was plugged
in. :)
>>
>> On Jan 6, 2012, at 19:24, "Don Lewis" <dlewis6...@austin.rr.com> >> wrote:
>>
>> > Can someone please give me some pointers (my first time with a GPS
>> module).
>> >
>> > A little hand-holding, pls.
>> >
>> > I bought three of these Rockwell D200 GPS receivers. (It's little >> > GPS
PWB
>> > with an antenna connector and pins for connecting to the RS232- PC)
>> >
>> > All three 'appear' to work the same way (no apparent capture of
>> satellites).
>> >
>> > Here's what I have:
>> >
>> > 1.    VisualGPS installed and running.
>> > 2. A small USB-RS232 card installed and appears to be >> > operational.
>> > 3.    Small GPS active antenna plugged in.
>> > 4.    VisualGPS monitor just repeatedly displays:
>> > $GPGGA,,,,,,0,00,,,,,,,*66
>> > 5. I think I understand this to be NMEA code to mean no >> > satellites
>> have
>> > been acquired.
>> > 6.    The Rockwell D200 draws ~180ma (5V) with no antenna and ~190ma
with
>> > the small active antenna plugged in.
>> >
>> > What am I doing wrong?  Other than maybe cheap china gps' and
antenna???
>> > But it is what I could afford and thought it would be cheap to learn
on.

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