Starting Over: Dish alignment

[cappuccino99]

I know that this is a silly question, but what is the difference between C and Ku Bands?

C band is a lower frequency/ longer wavelength & so uses a bigger lnb to receive it, it clashes with some ground based frequency use so it can't be transmitted as powerfully as Ku band which doesn't clash and so means you generally need a bigger dish for c band although it's got a little easier on smaller dishes lately. It is less effected by rain than Ku band and can be used with quite open wire mesh dishes & can tolerate more outage on dishes. Otherwise it behaves the same once received & down converted by the LNB.

Ku is a much higher frequency, uses smaller lnbs, can be transmitted at higher power without causing excessive interference and so can use smaller dishes to receive it but is more effected by rain.

C band would probably be history by now except it is better in areas with regular heavy rain. In the recent heavy rains for example, ku band was badly effected but C band mostly carried on unaffected.

 

[EMPB]

Satellite communication systems are subject to international agreements and regualtions. The International Telecommunication Union (ITU) regulates frequency use and defines "bands"

The following bands are commonly used:

C-band was the first band to be used for satellite communication systems, inc DTH (Direct To Home Satellite Services, TV Distribution, Subscription, Free to Air). However, when the band became overloaded satellites were built for the next available frequency band, the Ku-band. The C-band frequency range has one significant problem. It is the frequency region assigned to terrestrial microwave radio communication systems. Larger Dishes were required. At the current point of time - C Band nevertheless is still used.

3.7 – 4.2 GHz

Advantages:

Less disturbance from heavy rain fade

Disadvantages:

Needs a larger satellite dish (some signals are now powerful enough for smaller dishes)
Possible Interference from microwave links

Ku-band is now typically used for broadcasting, inc DTH and 2-way Internet connections. The Ku-band frequency range is allocated to be exclusively used by satellite communication systems, thereby eliminating the problem of interference with microwave systems. Due to higher power levels at new satellites Ku-band allows for significantly smaller dishes.

Low Band: 10.7 to 11.7 GHz. High Band: 11.7 to 12.75 GHz

Advantages:

No interference from microwave links and other technologies
Operates with a smaller satellite dish (diameters from 90cm) -> cheaper and more easy installation

Disadvantages:

Sensitive to heavy rain fade (significant attenuation of the signal) / possibly can be managed by appropriate dish size etc.

The myth: At the inception of satellite communications in C-band was the only option. It has been the long held belief that Ku-band could not be deployed due to the torrential rains in regions like in Africa. However, with the technology progress in the satellite industry (invention of better LNBs, Dishes, Low threshold receivers), and the more powerful satellites. This thereby eliminates the impact of heavy showers. Its all a matter of correct design and proper equipment to make Ku-band same stable than C-Band to rain factor influence.

The newest band being Ka-Band...... used by Saorsat (a free-to-air satellite service in Ireland) on 9E, but now there are a few satellites with Ka-Band Frequencies/Beams over the frequencies of 26.5–40 GHz.

edited (shortened, yup it was longer!!!, lol) as our friend above beat me to it

 

[EMPB]

Yep:

C band would probably be history by now except it is better in areas with regular heavy rain. In the recent heavy rains for example, ku band was badly effected but C band mostly carried on unaffected.

For me in Ku-Band 15W byu TV Global dropped from 100% to 80%, when it rained the last few nights, but absolutely no noticable difference to strength of Rossia 2 on 11W in C-Band.

 

[pevla]

Very interesting and enlightening answers, thanks guys!

 

[sweash58]

Cant get Thor on my system. I have a Spiderbox 9000hd and live in S.W. Scotland. Any help would be grateful. Thanks

 

[mdt]

Cant get Thor on my system. I have a Spiderbox 9000hd and live in S.W. Scotland. Any help would be grateful. Thanks

which transponder are you using? 11.862.H.28000 is a good one to start with. if everything is correct(pole plumb,dish straight on spiggot,usals entered,lat correct on motor,dish elevation set to 25,send dish to thor on spiderbox) then patience is the key really. you need to made small slow movements left to right and if no signal then ajust the dish upwards slightly and repeat the process. even with a proper field meter sometimes you can swing the dish about for ages and get nothing then all of a sudden, BOOMING IN!. just keep trying you will get there,regards mdt