[HCARC] Robotics/ Satellite Tracking Rotator

Mon Aug 21 11:31:26 EDT 2017

Gpredict - a linux program, and one of the nicest sat tracker's out there...

looks as if some Kerrville hams have seen the light.

AF5SA

ps: said this before:

Windows 10 is a virus that imitates an operating system (OS).

On 8/20/17, Virgil Bierschwale <vbiersch at gmail.com> wrote:
> 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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>>
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>
>
>
>
> --
> Virgil Bierschwale
>
> American Made Software
> http://www.americanmadesoftware.com/
>
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