[amsat-bb] On satellite beacons and rotator mounting [was: Re: Re: Sat Demo Yesterday]

[Johann Lochner]

On Saturday, 2010-10-23 13:49 +0200, N. Mahdinejad wrote:

> Dear satellite operators.
> Is there any one? i dont recive any answer to my questions. help ma please.
> Which of amteur satellites have operatonal beacon downlink ?
> 
> Thanks for your attention.
> Best Regards.

Dear N.

Be more patient: the majority of subscribers to this group are 
probably from the North American continent.  It is Saturday and their 
day is just beginning.

Preferably also start a new thread with a subject line that properly 
describes your issue.  Under another topic people might just skip 
over your message without reading it.  They may also be more inclined 
to respond to messages signed with a first/given name or an amateur 
radio callsign.

Regarding your question about beacons -- these pages are valuable 
references:

Live OSCAR Satellite Status Page
http://oscar.dcarr.org/

Operational OSCAR Satellite Status Summary
http://www.amsat.org/amsat-new/satellites/status.php

Regarding your earlier question about where zero azimuth is -- I am 
not familiar with Unitrack but presume that it is similar to the 
Yaesu GS-232B controller box for the Yaesu G-5500 motor controller.

When mounting a rotator there are two angle references that must be 
related to each other in some way:

The first is the hardware read-out that will vary between the 
extremes of rotation, according to the mode selected.  In the case of 
the GS-232B it runs from 180 through 360/0 to 180, or from 0 to 359, 
or from 0 to 450.  It is a scale to measure the relative hardware 
rotation.

The second is the mathematical definition of direction, which is 
normally measured as an angle relative to true north, with clockwise 
being positive.

Your control software must have a setting to link a specific hardware 
read-out value to where the rotator/antenna actually points.  The 
relative scale is thereby anchored to the mathematical definition of 
direction.

73 de ZR1CBC, Johann.