Re: [amsat-bb] Looking for the GS-232 protocol specs

[Lee Scott - AA1YN <aa1yn@xxxxxxxxx>]

It seems like I opened a can of worms. I got 10 copies of the GS-232 
documentand now a lot of you are asking for details.

Rather than replying individually, here is what I am building:

The EME array will be a 4 X 16 ele crossed yagi mounted on a 20 foot tower. 
I have the H frame built. The mast is a schedule 40 galv. 2" pipe 24 foot 
long mounted inside a 20 foot Rohn 25 tower with home made thrust bearings. 
Except for the supporting tower, the H frame, mast and rotor could probably 
handle an array twice this size.

The azimuth rotor is a 36v DC motor off of a TVRO and has 8 pulses per 
revolution with a 60rpm output.  This feeds a 100:1 speed reducer which was 
given to me by friend and has a 1/2" double chain drive output.  This feeds 
the chain sprocket on the mast giving an additional 3:1 reduction.  I 
figure if the antenna ever gets stuck, I will probably re-adjust the earths 
rotation :-)

The azimuth portion is up and running controlling the rotor drive both 
manually and auto with feed from Nova. I am at present using the EasyComm 
protocol as it gives me the bearing and elevation in 10ths of a degree. I 
have a variable deadband setting.  I do need to provide variable speed for 
the azimuth for starting and stopping the rotation.

The elevation drive is a standard TVRO linear actuator and I'm about to 
start the programming on that.  It should be straight forward except for 
the sin calculations but I think I've got that solved also.  The whole 
thing is based on a PIC18LF458 micro controller.

I tore apart the controller I got along with the TVRO Drive motor and with 
a new processor board and a new front panel, it is looking somewhat 
professional.  I have a pair of 4 digit LED readouts for Az and El along 
with manual controls. The motor drive circuitry is built into the 
controller for both Az and El and is based on IR Power FETs in an H switch 
configuration.

I took a look at the GS-232 spec and I think I like the EasyComm protocol 
better. One thing I'm looking at is the 0.15 degree accuracy of my drive 
system as it is all digital and no analog input.  Just count the pulses. I 
have made provisions for analog voltage input for both the Az and El drives 
but in this case, I don't think I will be using them. If I do, it will only 
be as a double check to see if something has gone wrong.

I have some photos up my website for those interested.  The link is 
http://www.aa1yn.com/eme/moontracker/moontracker.html


Lee Scott - AA1YN http://www.aa1yn.com
Home of the VHF & Up Register http://www.aa1yn.com/vhf
Hooksett, NH
FN43gc52
----
Sent via amsat-bb@amsat.org. Opinions expressed are those of the author.
Not an AMSAT member? Join now to support the amateur satellite program!
To unsubscribe, send "unsubscribe amsat-bb" to Majordomo@amsat.org