Good signal on SD channels and Poor signal on HD

[eg4]

Last week I ve installed an ET4000 for my friend on a fixed dish with 2 LNB's one for hotbird 13E and the other astra 19.2E, on both I can receive SD channels but when coming to HD a lot of them have a poor quality and so the receiver give a failed tune error. This happened again today on a VU+ solo, but this time the dish is motorized with 1 LNB and still I am getting good signal on SD nearly 94% while on HD I get less than 45%. Is it a problem with old LNB's, diseqc switch or is it from the sharing side as both of them have the same source of sharing..... can any one help me out? Thanks.

 

[Rob van der Does]

Generally HD-transponders require a better dish-aligning their SD brothers.

When you say 'signal xx%' I hope you mean SNR, as AGC is not worth looking at.

 

[eg4]

Yes SNR as AGC is always 0.

Generally HD-transponders require a better dish-aligning their SD brothers.

When you say 'signal xx%' I hope you mean SNR, as AGC is not worth looking at.

 

[eg4]

so how come the dish is not aligned when I can get 94% on SNR...

 

[Rob van der Does]

Depending on the circumstances, such as FEC, the box can make a good signal even when not properly aligned.
When the circumstances are different, a lower FEC and another, more demanding modulation, the box can't get the same level of SNR.

So best would be to align the dish when tuned to a (weak) HD transponder. And don't forget the skew.

 

[eg4]

And don't forget the skew. What does it mean as I am no expert? sry.

Depending on the circumstances, such as FEC, the box can make a good signal even when not properly aligned.
When the circumstances are different, a lower FEC and another, more demanding modulation, the box can't get the same level of SNR.

So best would be to align the dish when tuned to a (weak) HD transponder. And don't forget the skew.

 

[Rob van der Does]

The angle the LNB has (turn it a bit in it's fitting). This does not apply to a motorised dish, but to all fixed dishes.
If you have a motor, turn it a bit to the West or East, and see how that angle changes. In a motorised dish this goes automated, due to the geometry of the setup; for a fixed dish this has to be done by hand (a fixed value for every satellite).