[HCARC] Robotics/ Satellite Tracking Rotator

Sun Aug 20 19:11:01 EDT 2017

I might play with this in another month or two.

looks like you can buy this and interface it to the az/el mount and it
should be easy to program it.

http://www.mcmelectronics.com/product/82-12445?green=35C8B1A2-D542-5161-B097-26792DEC5E84

On Sat, Aug 19, 2017 at 5:10 PM, Kerry <kerryk5ks at hughes.net> wrote:

> Gale,
>
> I'm not quite sure what your application is.  If it is tracking satellites
> at 2 m and 70 cm your tracking requirements aren't very difficult.  In the
> early days of Oscar I used a 10m 3-element Yagi and a 3-element 2 m Yagi.
> The 10 m antenna was not up very high and so had little directivity and
> most of the pattern was up.  The 2 m yagi also had a 3 dB beamwidth of
> about 60 degrees.  The 2 m antenna was mounted at an angle of 45 degrees
> above the horizon. I would only have to move the antenna twice to cover the
> longest pass.  60 degrees is approximately a radian.
>
> When you look at an optical telescope, because the wavelength is so short,
> the beamwidth is very much narrower, even for small telescopes.  A 4 inch
> (10 cm) aperture telescope would have a beamwidth on the order of a
> microradian, a million times narrower than 3-element Yagis.
>
> To track the early OSCAR satellites in polar orbit all you really needed
> was the time and location of the equator crossings which was transmitted by
> W1AW.  Life is infinitely easier now.  I use a program called Gpredict.  It
> has as an output polar and az-el plots of the satellite you specify at your
> location and includes time data.  It uses the two line element sets (TLEs)
> from US Space Command.
>
> Even a 1 m dish at X-band has a beamwidth of about a tenth of a radian, 6
> degrees.
>
> If you recall when direct satellite TV at Ku band first started, you were
> able to aim the dish close enough to the correct location knowing only your
> lat and lon and a magnetic compass and the built in elevation scale on the
> dish mount.  With your lat and lon, the satellite receiver gave you the
> compass bearing and elevation setting to aim the dish.
>
> If you haven't already, you need to take a look at the satellite tracking
> programs available like Gpredict to see the type tracking data available
> and use it to look at the amount of change of azimuth and elevation and the
> time during a pass.  That should help you decide how much resolution and
> speed you need to do the tracking.  I think you will be surprised how low
> the resolution and speed requirements really are.
>
> I would recommend reading "The Satellite Experimenters Handbook" 1st
> edition (1985) by the ARRL.  It really gives a practical feel for how to do
> it and the equipment required.  Like so many things in ham radio, the
> manufacturers and the ARRL have gone out of their way, in the interest of
> profits, making simple things incredibly complicated.
>
> Kerry
>
>
>
>
> On 8/19/2017 3:25 PM, Gale Heise wrote:
>
>> A number of people responded so I’m going to simply reply to the
>> reflector and please just ignore me if you’re not interested.
>>
>> First I’d like to thank John Trolinger for providing input previously.
>> He has a neat satellite tracking system at his place by simply pointing the
>> antennas at 45 degrees and utilizes a Channel Master rotator.  He connects
>> his computer to the rotator via a computer interface and can track the
>> satellites.  I’m trying to see if there is a simple and inexpensive way to
>> obtain elevation control as well as azimuth.
>>
>> Also, thanks to those expressing an interest in helping me and learning
>> more about robotics.
>>
>> Today many hams are working satellite stations simply with hand held
>> antennas such as the Arrow 146/437-10WBP.
>> http://www.arrowantennas.com/arrowii/146-437.html
>>
>> Here is an example of someone working a satellite with a tripod:
>> https://www.youtube.com/watch?v=1HfvmU_utI8
>>
>> Attempting to locating the satellite and track it manually is very
>> frustrating as I have found the case through personal experience.  To
>> purchase a Yaesu G-5500 AZ/EL rotator, cable and computer interface box it
>> is expensive ($1,000+) and overkill for a hand held or small array antenna
>> system.
>>
>> As a result, I started searching the internet for a less expensive
>> alternative with the WRAPS system as one choice.  The first video is by the
>> inventor and the subsequent videos are by a person who actually built the
>> WRAPS system from parts:
>> https://www.youtube.com/watch?v=K5Xx6K7tM0Y
>>
>> Wraps Assembly and Testing – Unless you understand Spanish, skip Video #2
>> 1. https://www.youtube.com/watch?v=gntz0d-NQPc
>> 2. https://www.youtube.com/watch?v=Nze3ZFRupuM
>> 3. https://www.youtube.com/watch?v=XqTkkQYNYd0
>> 4. https://www.youtube.com/watch?v=2tFw8tz7WW0
>> 5. https://www.youtube.com/watch?v=qJOKr1KcVoY
>>
>> I thought the WRAPS system was on the lightly constructed side and not
>> really meant to be all weather.  It addition, it’s about $300 for the
>> parts.  So I began looking for existing systems that could be adapted.  One
>> idea came to me when I thought about my neighbor who has a tracking system
>> on his telescope and I found this video:
>> https://www.youtube.com/watch?v=BDTjnJm41mc
>>
>> Here is a link to purchasing a telescope mount:
>> https://www.celestron.com/products/nexstar-slt-computerized-mount
>>
>> It also requires a computer interface:
>> https://www.amazon.com/s/ref=nb_sb_ss_c_1_10?url=search-alia
>> s%3Daps&field-keywords=skyfi+wireless+telescope+controller&
>> sprefix=skyfi+wire%2Caps%2C295&crid=2RZ1O8B4040C6&rh=i%
>> 3Aaps%2Ck%3Askyfi+wireless+telescope+controller
>>
>> Again, the price is way more that I want to invest.  Over half of the
>> cost of the G-5500.  So I continued to search for an all weather system and
>> came across a video that I can’t find now.  It was of a fellow utilizing a
>> Defender Security pan/ tilt camera platform.  He utilized the matching
>> controller and manually tracked the satellite.  Here is a heavier duty
>> model built for the weather:
>> https://www.amazon.com/Defender-Security-82-12440-Outdoor-
>> Heavy/dp/B002MZ8GU2/ref=sr_1_sc_1?s=electronics&ie=UTF8&
>> qid=1503171732&sr=1-1-spell&keywords=defendersecurity+pan+tilt
>>
>> There’s a Techno-Geek website called hackaday.io.  On it’s site I found
>> a fellow who purchased the Defender Security 882-12440 and built a
>> controller for it to swing up and down, back and forth to water his lawn.
>> He has five different files posted showing his progress through the project
>> beginning with a disassembly of the unit to take a look inside:
>> https://hackaday.io/project/20572-ptsprinkler/log/57784-diss
>> ecting-the-pantilt-stage
>>
>> In addition, here is a video from AE0MT who is utilizing an inclinometer
>> and GPS chip;
>> https://www.youtube.com/watch?v=HE09wMaTUpU
>>
>> There was another satellite video whereas the fellow was utilizing a
>> stepping motor to obtain feedback on position rather than a potentiometer
>> system as utilized in the WRAPS system.
>>
>> Here’s where I’m looking for input.  One can purchase the Defender
>> Outdoor Heavy Duty Pan Tilt for about $60.  I believe the fellow who
>> assembled the WRAPS system said the electronics parts were about half the
>> total cost so about $150.  So I’m curious if there is any way to add
>> positioning feedback to the Defender and control it with a computer as with
>> the WRAPS system.  It may mean replacing the motors within the Defender
>> with stepping motors in order to obtain feedback for the positioning system
>> or adding inclinometer and GPS chips as did AE0MT.
>>
>> It’s a lot to wade through so I’m not offended if people aren’t
>> interested in pursuing.  If you get through it all I’d appreciate your
>> thoughts.
>>
>> Take care,
>>
>> Gale
>> KM4DR
>>
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