Inclination

F

fergyc

Regular Member
My Satellite Setup
VU+ Duo with ViX and OSCAM, Prof Revolution 7301 PCI Card, 2x Dreambox 500S, 80cm Technomate Dish with Inverto Black Ultra and TM-2600 DiSEqC Motor. Technomate TM-300D along with a few zone 1 minidishes that get moved regularly and a zone 2 for 19e a
My Location
Northumberland
I've seen this mentioned a few times, like Astra 1C being inclined by 8 degrees or so, but what does it actually mean?
 
A satellite is usually put into an inclined orbit towards the end of it's life. It takes less fuel to hold it in orbit when it's inclined than a true geo-stationary orbit. The satellites thrusters are still used to hold the sat to it's orbital position, i.e 8w, but stop being used to hold it exactly on the clarke belt, so the satellite kinda does a figure 8 over it's correct position.

What that means for reception is that you can only recieve the satellite at certian times of the day, or you need to alter the declanation of the dish to track the satellite. You can get inclined tracking setups, that use an actuator for declanation adjustment, in exactly the same way one would be used for azimuth adjustment, therby allowing 24hr reception. Sat's in inclined orbits are mostly used for feeds, as they are harder to recieve for most people.

_http://en.wikipedia.org/wiki/Inclined_orbit - probably gives a better explanation than I just did.
 
It's not put into an inclined orbit on purpose, it's just that there is no corrective input. If you imagine the geostationary track as a road through space and the satellites as cars going down that road if the road had negative camber (i.e. water runs to the centre) a car going down the road would always stay in the centre and would not need any input from the driver... but if the road had positive camber (i.e. water runs off the sides) a car travelling along that road would also have a tendency to run off the sides and would need continual corrections from the driver to keep it going down the centre. The geostationary track is similar to the positive camber road because there small influences like the gravities of the sun and moon which pull the satellite off the centreline and, without any corrective input, make it wander around from side to side across the geostationary track. Because of this all satellites are inclined to some degree. For DTH services where the dish is fixed it is a balancing act between not wasting fuel keeping the satellite at 0º inclination, but not allowing the inclination to deteriorate to the point where a fixed dish can't receive it 24 hours a day in the intended reception location.
 
Baring any technical fault, there is a decision made by the operator to stop making the required corrections to keep the satellite geostationary to prolong the life of the satellite, so it is allowed to go inclined on purpose. And while yes all satellites are inclined to a degree, they aren't classed as inclined when describing them if they can be recieved 24hrs a day by a fixed dish in my experience.
 
So that's why I got Astra 1C yesterday at this time but no sign of it later on!
 
Rick said:
Baring any technical fault, there is a decision made by the operator to stop making the required corrections to keep the satellite geostationary to prolong the life of the satellite
Click to expand...
Exactly, but once that happens it is no longer any use as a DTH satellite. Also it might not mean no corrections, just less frequent ones.
 
This site:

-http://www.n2yo.com/?s=22653

will tell you where on the wobble Astra 1C is at any time. (She's currently 3.8 degrees inclined so is 3.8 degrees off the main orbital plane at the extremities of the swing - way outside the capabilities of any dish not equipped with Inclined Orbital Tracking)



As an inclined sat wobbles up and down on the figure 8 it will pass through the centre line of the 8 twice a day. At these times the bird will be received as normal. However unless you have IOT she will eventually wander north or south enough to break the reception.

The transmission should be received at approximately the same time each day so if you are currently getting reception at teatime you should be ok at the same time of day for the next few months.
 
Analoguesat said:
The transmission should be received at approximately the same time each day so if you are currently getting reception at teatime you should be ok at the same time of day for the next few months.
Click to expand...

I'm finding this fascinating, as I'm able to catch 10967V on 40°E from early afternoon till early evening (in fact it's breaking up now at 19:00 CET). It explains why I was getting so frustrated when I checked on a morning and got zero! I might try a scan for the other European beam TP's when it's 'sitting on the belt'.
 
AM1 at 40E lost her onboard thrusters back in April so cant do north-south station keeping any longer. However shes only 0.3 degrees inclined so shouldnt be too bad atm
 
Rick said:
You can get inclined tracking setups, that use an actuator for declanation adjustment, in exactly the same way one would be used for azimuth adjustment, therby allowing 24hr reception.
Click to expand...

Rick, (or anyone else) just out of curiosity, what tracking controllers are available for inclined tracking?
Do these work on a polar mount (as opposed to Az over El)?
How do they detect signal level - do they use signal level from the receiver or is a seperate beacon receiver used?
Do they require some resolver feedback or can it work on pulses from the actuator?

I'm familiar with the Research Concepts RC2000 models working on an Az over El mount with beacon receiver, but I would have thought that was a bit out of reach for the domestic market.
 
You can modify a polar mount and introduce a second actuator for elevation. Some drilling, bolting and maybe welding and job done in most cases.
You could use a V-Box manually for EL adjustment on the second actuator. I've seen somewhere that there's a bit of kit for the PC that will control 2 actuators and give quite precise AZ/EL tracking. It works on the same principal as USALS, but continually re calculates the position as opposed to only doing it when a differamt satellite is selected. Can't for the life of me remember where I saw it or what it was called though :s
 
The old Jaeger 1224EL motor was tailor made for this, as it had a fixing for an actuator, there are probably a few still floating around.
 
rolfw said:
The old Jaeger 1224EL motor was tailor made for this, as it had a fixing for an actuator, there are probably a few still floating around.
Click to expand...
There were 2 models. Only one takes the elevation actuator. Mine doesn't. The Motech clone of the 1224 looks like it would take the elevation actuator directly.
_http://www.satellitesuperstore.com/motors.htm#36vhtoh
 
Yes, that's why I mentioned the model number 1224EL, as that is the one with the elevation actuator.
 
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