Hello All. I have a couple of Orbit -360 rotator and I stumbled across an old Amsat article on using them with a digital pot for computer positioning. My question is has anyone done this and what kind of program was used to control the pot? I'm currently using Gprdict. Thanks
I remember that project! I saw the original at AA2TX's place. I built a system and wrote my own Linux software since Tony was a DOS/Windows guy, the essence of which was to talk to Predict via UDP and ask it where to point once every 30 seconds, and then bit bang the LPT port to signal the hardware to output a new voltage. It was a while ago so the details are fuzzy, but I think the stock Predict (and I think Gpredict has the same capability) worked, but I may have hacked it.
If I were to do it again today I'd consider something similar, but maybe use an Arduino with a couple of DAC's attached and talk to it via a USB/serial converter. Alas in 2022 Orbit 360 rotors and LPT ports are hard to come by!
de KM1P Joe
Hi James,
A few years ago, I was where you are now, looking at how to update the AA2TX approach. After a lot of digging around, I discovered a project named SAEBRTrack by Mark Hammond, N8MH, and Gene Brigman, KC4SA. They built a controller for a pair of Orbit 360 rotators, using a BASIC Stamp to provide an EasyComm interface to it.
https://sites.google.com/site/marklhammond/saebrtrack
Starting from that, I came up with something that uses an Arduino (Nano Every) as the controller, along with a 4-relay board from eBay. I wrote my own EasyComm code for the Arduino, tested with Gpredict and HamLib. I got as far as "proof of concept", which is to say that I got things working, but both hardware and software never quite got finished, since I got distracted by other things and never quite seemed to get back to it.
This is absolutely a doable and fun project. While I'm sure something could still be done with the original AA2TX digital pot approach, I think borrowing from the SAEBRTrack approach will result in a more complete solution.
By the way, Joe, you might be surprised at how frequently Orbit 360 rotators come up on eBay!
Martin. KD6YAM
On Tue, Feb 8, 2022 at 4:36 AM James Hickox [email protected] wrote:
Hello All. I have a couple of Orbit -360 rotator and I stumbled across an old Amsat article on using them with a digital pot for computer positioning. My question is has anyone done this and what kind of program was used to control the pot? I'm currently using Gprdict. Thanks
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Martin,
Yes a SAEBRTrack type approach is more general purpose than the AA2TX digital pot solution, it can be used with pretty much any pair of rotors. Tony was never really happy unless you could fill your entire bill of materials for less than $5 - and 4 relays plus the microcontroller and drive electronics blows that budget!
I checked eBay, and apparently missed my opportunity in December for two new old stock Orbit 360's. I did find an RCA rotor only deal that I could not pass up though ... it arrives this weekend!
de KM1P Joe
Hi Joe,
Ha ha! You're right there. I think my total came to about $50, including a case, which was the most expensive item. A lot more than the digital pot solution, but not too bad for a complete rotator controller.
Martin. KD6YAM
On Tue, Feb 8, 2022 at 10:23 AM Joseph B. Fitzgerald < [email protected]> wrote:
Martin,
Yes a SAEBRTrack type approach is more general purpose than the AA2TX digital pot solution, it can be used with pretty much any pair of rotors. Tony was never really happy unless you could fill your entire bill of materials for less than $5 - and 4 relays plus the microcontroller and drive electronics blows that budget!
I checked eBay, and apparently missed my opportunity in December for two new old stock Orbit 360's. I did find an RCA rotor only deal that I could not pass up though ... it arrives this weekend!
de KM1P Joe
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BTW, check the latest QST for another piece of the puzzle. This guy gets the azimuth reading from the single-chip magnetometer. Someday I thought it would be fun to use a magnetometer and an accelerometer (to measure the acceleration due to gravity) to get both Az and El without pots.
On Tue, Feb 8, 2022 at 2:31 PM Martin Cooper via AMSAT-BB < [email protected]> wrote:
Hi Joe,
Ha ha! You're right there. I think my total came to about $50, including a case, which was the most expensive item. A lot more than the digital pot solution, but not too bad for a complete rotator controller.
Martin. KD6YAM
On Tue, Feb 8, 2022 at 10:23 AM Joseph B. Fitzgerald < [email protected]> wrote:
Martin,
Yes a SAEBRTrack type approach is more general purpose than the AA2TX digital pot solution, it can be used with pretty much any pair of rotors. Tony was never really happy unless you could fill your entire bill of materials for less than $5 - and 4 relays plus the microcontroller and drive electronics blows that budget!
I checked eBay, and apparently missed my opportunity in December for two new old stock Orbit 360's. I did find an RCA rotor only deal that I could not pass up though ... it arrives this weekend!
de KM1P Joe
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I have used a 9 DOF sensor on the tail of the PVC cradle that sometimes holds my Elk. It provides the feedback to an ESP processor that sends commands to the az and el servos. There’s also a GPS board that tells the ESP where the antenna is located. TLEs are wifi’d to the tracking code on the ESP. The design of this autonomous, portable satellite tracker was developed a few years ago by WB0OEW and published in QEX. The DOF sensor includes an accelerometer and magnetometer. My comment is that these can be pretty cranky, although there may be better boards now available. Cranky in that 1) the sensor I have requires a frequent calibration ritual and 2) RF sometimes drives it crazy despite liberal use of ferrites and wrapping the sensor in foil. I appreciate the references in this thread because I want to build a new tracker that uses just the servos and the servo control board from the old one. I’d like to interface the servo controller over a USB cable to a laptop running SatPC32. Wish I could get this figured out before FD this year so I can stay sealed inside the tent at night while the tracker does its thing outside. The bugs were horrible last year. Ray KN2K
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On Tuesday, February 8, 2022, 6:36 PM, Burns Fisher [email protected] wrote:
BTW, check the latest QST for another piece of the puzzle. This guy gets the azimuth reading from the single-chip magnetometer. Someday I thought it would be fun to use a magnetometer and an accelerometer (to measure the acceleration due to gravity) to get both Az and El without pots.
On Tue, Feb 8, 2022 at 2:31 PM Martin Cooper via AMSAT-BB [email protected] wrote:
Hi Joe, Ha ha! You're right there. I think my total came to about $50, including a case, which was the most expensive item. A lot more than the digital pot solution, but not too bad for a complete rotator controller. Martin.KD6YAM On Tue, Feb 8, 2022 at 10:23 AM Joseph B. Fitzgerald [email protected] wrote:
Martin,
Yes a SAEBRTrack type approach is more general purpose than the AA2TX digital pot solution, it can be used with pretty much any pair of rotors. Tony was never really happy unless you could fill your entire bill of materials for less than $5 - and 4 relays plus the microcontroller and drive electronics blows that budget!
I checked eBay, and apparently missed my opportunity in December for two new old stock Orbit 360's. I did find an RCA rotor only deal that I could not pass up though ... it arrives this weekend!
de KM1P Joe
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I heard SAEBRTrack is a good project ;)
73!
P.S. My call at the time was KC4EBR....and my elmer was KC4SA. SA+EBR = SAEBRTrack..... Just over a year ago, he became SK. :(
Mark L. Hammond [N8MH] AMSAT Director and Command Station
On Tue, Feb 8, 2022 at 11:10 AM Martin Cooper via AMSAT-BB < [email protected]> wrote:
Hi James,
A few years ago, I was where you are now, looking at how to update the AA2TX approach. After a lot of digging around, I discovered a project named SAEBRTrack by Mark Hammond, N8MH, and Gene Brigman, KC4SA. They built a controller for a pair of Orbit 360 rotators, using a BASIC Stamp to provide an EasyComm interface to it.
https://sites.google.com/site/marklhammond/saebrtrack
Starting from that, I came up with something that uses an Arduino (Nano Every) as the controller, along with a 4-relay board from eBay. I wrote my own EasyComm code for the Arduino, tested with Gpredict and HamLib. I got as far as "proof of concept", which is to say that I got things working, but both hardware and software never quite got finished, since I got distracted by other things and never quite seemed to get back to it.
This is absolutely a doable and fun project. While I'm sure something could still be done with the original AA2TX digital pot approach, I think borrowing from the SAEBRTrack approach will result in a more complete solution.
By the way, Joe, you might be surprised at how frequently Orbit 360 rotators come up on eBay!
Martin. KD6YAM
On Tue, Feb 8, 2022 at 4:36 AM James Hickox [email protected] wrote:
Hello All. I have a couple of Orbit -360 rotator and I stumbled across an old Amsat article on using them with a digital pot for computer positioning. My question is has anyone done this and what kind of program was used to control the pot? I'm currently using Gprdict. Thanks
Sent via AMSAT-BB(a)amsat.org. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Acceptable Use and Privacy Policies available at https://www.amsat.org/about-amsat/
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Sent via AMSAT-BB(a)amsat.org. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Acceptable Use and Privacy Policies available at https://www.amsat.org/about-amsat/
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participants (6)
-
Burns Fisher -
crohtun＠aol.com -
James Hickox -
Joseph B. Fitzgerald -
Mark L. Hammond -
Martin Cooper