[Laser] Telescope & GPS interfac

[Terry Morris W5TDM]

>From: "Chuck Hast" <wchast at gmail.com>
>Reply-To: Free Space LASER Communications <laser at mailman.qth.net>
>To: "Free Space LASER Communications" <laser at mailman.qth.net>
>Subject: Re: [Laser] Telescope & GPS interfac
>Date: Wed, 18 Jul 2007 23:59:53 -0400
>
>On 7/18/07, Terry Morris W5TDM <w5tdm at hotmail.com> wrote:
>>Hello Chuck & group,
>>
>>Here is what I found out so far:
>>
>>Garmin GPS has serial port @ 4800 Baud and will output the following data
>>types:
>>GARMIN, NEMA 0183 V 2.00, RTCM/NEMA, RTCM. Baud rate doesn't appear to be
>>changable.
>>
>>Celestron Telescope has a serial port @ 9600 Baud ( first problem). The
>>telescope "Get Position Command" is looking for position data in either
>>RA/DEC or AZM-ALT coordinates. (second problem).
>>
>>So it is looking like a laptop and software may be one answer. The other
>>answer is the Celestron GPS Module @ $199.00 is looking a lot cheaper all
>>the time.
>>
>>I know there are a lot of people on the list with a lot of knowledge on 
>>GPS
>>interfacing, does anyone see something I am missing.
>>
>I think the term is "Protocol Converter"... You probably want something 
>that
>can take the proprietary GARMIN protocol (it I believe has a bit better 
>resol-
>ution than the NMEA protocol. RTCM is used for differential GPS and is wh-
>at the differential station sends to the differential receiver to
>correct the GPS
>data for propagation and other errors. Your GARMIN connected to a differen-
>tial receiver with the frequence for the differential transmitter out on 
>Egmont
>key (local differential base station in the Tampa Bay area) could supply 
>you
>with some pretty accurate position info... If you have a differential base 
>sta-
>tion in your area you can use that, and it will give you better accuracy, 
>but
>you need the data to have enough resolution. NMEA does DDMM.MMM or
>it does DD.dddddd I believe, but need to check it. I do not know how much
>accuracy you need. You will also need to know what the protocol looks like
>that you feed to scope, and then get someone to code up a converter...
>

Hi Chuck,

I googled Protocol coverter, everything I found was for conversion between 
RS-232 ans either 422 or 485.

So for now I am just going to manually enter data from the GPS to the 
telescope controller. Then when my pocket book recovers a little I may go 
for the Celestron GPS. Right now they just have it on sale for $199.00 from 
$329.00. I think Celestron probably made there GPS interface different from 
any standard so they could sell more GPS units. That was Chris Maness KQ6UP 
opinion which I share.

Thanks fo rthe information,
73
Terry W5TDM

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