[time-nuts] Getting my Rockwell D200 GPS to work

David davidwhess at gmail.com
Sat Jan 7 17:16:38 UTC 2012


I am not suggesting this as a replacement for a proper GPS antenna.  I
am suggesting it as a inexpensive sanity check.  The loss from
receiving a circularly polarized signal with a linearly polarized
antenna (or the reverse) is 3db.

On Sat, 7 Jan 2012 17:29:54 +0100, Azelio Boriani
<azelio.boriani at screen.it> wrote:

>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 <davidwhess at 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, shalimr9 at 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.boriani at screen.it>
>> >Sender: time-nuts-bounces at febo.com
>> >Date: Sat, 7 Jan 2012 02:00:21
>> >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] 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 <dlewis6767 at 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-bounces at febo.com [mailto:time-nuts-bounces at 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" <dlewis6767 at 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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