Re: [amsat-bb] Lock on Tracking

["Edward R. Cole" <al7eb@xxxxxxxxxxxxx>]

Thanks for reminding me:  

The tracking system initiates by going to pre-set coordinates for a given
satellite while the ship is at dock, then maintains lock afterward via
signal-strength.  There is also a reaquisition routine for loss of lock at
sea.  So it was a combination of predictive and signal-locking.  

Since this was most likely a psk signal I wonder if they may have used a
pilot carrier for tracking?  trying to lock on AO-40's telem beacon would
be a bit more difficult, I think.  The system was tied into the ship's
gyro-compass, as well!  Elevation tracking is merely a weighted pendulum
digital encoder.  

Polarization tracking was probably using the signal differential between
the two orthogonal signals.  The whole dish is rotated +/- 45-degrees in
polarization by a motor; w/g has dual rotating joints which I will remove
(all my equipment will be attached to the dish yoke). 

Frankly, I have no interest in trying this as predictive auto-tracking
works fine for amateur purposes (KISS).

Ed - AL7EB

At 09:23 AM 12/11/02 -0600, Ed Manuel wrote:
>Another problem is that if you don't have any prediction for direction of 
>motion, which way do you correct when the signal level fades.  You may end 
>up slewing the array several times to determine which way it went.  And you 
>only have two ways to slew the array.  Sounds like something like this 
>might really wear out rotors.
>
>A combination of predictive tracking and signal level feedback might be an 
>interesting approach.
>
>Ed
>
>
>At 08:17 AM 12/11/02 -0600, you wrote:
>>Hi Rod
>>   I have thought about building a system that would work by using the
signal
>>strength from the satellite as reference than a simple error amplifier
>>circuit to drive the AZ-El. But this may be very difficult if the signal
>>from the satellite fluxuates allot. With fast enough circuits and motors, it
>>seems possible, but it would probably take a good computer programmer to
>>develop a workable algorithm.
>>My thoughts
>>Ben K9BF
>>----- Original Message -----
>>From: "Rod Smallwood" <Rod@sbs293.customer.demon.com>
>>To: <amsat-bb@AMSAT.Org>
>>Sent: Wednesday, December 11, 2002 4:16 AM
>>Subject: [amsat-bb] Lock on Tracking
>>
>>
>> > Unless I am much mistaken everybody uses predictive tracking.
>> > Has anybody had any experience with Radar style tracking
>> > where the system locks on to the target (ie AO40) and follows
>> > it?
>> >
>> > Rod (G8DGR)
>> >
>> >
>> >
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>>
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