Pendulum type elevation measurement
For some time I have wanted a more accurate antenna elevation measurement system. Shaft encoders are beyond my budget. It seems sensible to use a pendulum operated system. Digging through my 'junk' box I find I have a new Spectrol precision potentiometer still sealed in it's package. This pot is 21mm diameter, has a servo type mount,, ball race bearing, 340 degree track (continuous rotation possible) and specification is 0.5% linearity.and is very low torque. Does anyone know if there are any drawbacks to using this method of position measurement. 73 de Dick G4BBH
I see no problems at all. I have done it with that method in the past. The only thing I noticed that was a problem was if the pendulum is exposed to the elements. As in weather not antenna elements. Gusty winds would move the pendulum and cause a not steady reading..
but not that much of a problem did not happen all that often.
Joe WB9SBD Sig The Original Rolling Ball Clock Idle Tyme Idle-Tyme.com http://www.idle-tyme.com On 2/24/2013 5:45 AM, Richard Ferryman wrote:
For some time I have wanted a more accurate antenna elevation measurement system. Shaft encoders are beyond my budget. It seems sensible to use a pendulum operated system. Digging through my 'junk' box I find I have a new Spectrol precision potentiometer still sealed in it's package. This pot is 21mm diameter, has a servo type mount,, ball race bearing, 340 degree track (continuous rotation possible) and specification is 0.5% linearity.and is very low torque. Does anyone know if there are any drawbacks to using this method of position measurement. 73 de Dick G4BBH _______________________________________________ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
I made an El rotor years ago, and used the weighted pendulum method for feedback. Besides the weather pushing the weight around, the other problem was hysteresus. Small changes in reverse position didn't cause any change in indication. If you are looking for improved position accuracy (vs what?), you should figure out a way to anchor the pendulum. That should solve both problems.
Greg KO6TH
Joe nss@mwt.net wrote:
I see no problems at all. I have done it with that method in the past.
The only thing I noticed that was a problem was if the pendulum is exposed to the elements. As in weather not antenna elements. Gusty winds would move the pendulum and cause a not steady reading..
but not that much of a problem did not happen all that often.
Joe WB9SBD Sig The Original Rolling Ball Clock Idle Tyme Idle-Tyme.com http://www.idle-tyme.com On 2/24/2013 5:45 AM, Richard Ferryman wrote:
For some time I have wanted a more accurate antenna elevation
measurement system. Shaft encoders are beyond my budget. It seems sensible to use a pendulum operated system. Digging through my 'junk' box I find I have a new Spectrol precision potentiometer still sealed in it's package. This pot is 21mm diameter, has a servo type mount,, ball race bearing, 340 degree track (continuous rotation possible) and specification is 0.5% linearity.and is very low torque. Does anyone know if there are any drawbacks to using this method of position measurement.
73 de Dick G4BBH _______________________________________________ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the
author.
Not an AMSAT-NA member? Join now to support the amateur satellite
program!
Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
On 02/24/2013 07:45 AM, Richard Ferryman wrote:
For some time I have wanted a more accurate antenna elevation measurement system. Shaft encoders are beyond my budget.
Do mice still have balls?
Once upon a time every old mouse had two optical shaft-encoders built right in. And mice can detect very tiny movements, so the sensors/encoders must be fairly precise. Nowadays, most mice are optical or 'laser', but apparently, some mice are still available with balls.
So, who is going to take a mouse apart and use the bits to sense AZ/AL angles on an antenna array?
Panasonic and others offer a single or 3 axis accelerometer for Wi game controllers. They provide outputs in analog, or digital. Sts and others also have these with only digital outputs. The Single axis unit is 0.2 " square by 0.1 " high runs on 5 VDC.
Art, KC6UQH
-----Original Message----- From: amsat-bb-bounces@amsat.org [mailto:amsat-bb-bounces@amsat.org] On Behalf Of Gus Sent: Sunday, February 24, 2013 1:15 PM To: amsat-bb@amsat.org Subject: [amsat-bb] Re: Pendulum type elevation measurement
On 02/24/2013 07:45 AM, Richard Ferryman wrote:
For some time I have wanted a more accurate antenna elevation measurement
system. Shaft encoders are beyond my budget. Do mice still have balls?
Once upon a time every old mouse had two optical shaft-encoders built right in. And mice can detect very tiny movements, so the sensors/encoders must be fairly precise. Nowadays, most mice are optical or 'laser', but apparently, some mice are still available with balls.
So, who is going to take a mouse apart and use the bits to sense AZ/AL angles on an antenna array?
El 24/02/13 16:14, Gus escribió:
So, who is going to take a mouse apart and use the bits to sense AZ/AL angles on an antenna array?
I have a sacrificed recently a roller-ball mouse from aopen to my az-el rotor system project...
I'm not decided yet for shaft vs. gray encoders... (gray encoders are almost winning... !!!)
6 bits gray encoders give 64 positions in 360 that's aprox 5 degrees steps... pretty good...
7 bits will be 2,8 degrees steps...
UTP cable is almost inexpensive.... has 8 wires ... hum... ground + 7 bits... interesting... parallel port of a PC as the input/output device... software will be written in python... (put your favorite prog. lang. here)
73
CO7WT.
participants (6)
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Art McBride -
Greg Dolkas -
Gus -
Ing. Pavel Milanes Costa -
Joe -
Richard Ferryman