14 replies to this topic

[bledi07]

To developers of Openpli image please fix this AGC issue on Zgemma H5.2S Plus.

Tried Openpli 4 and Openpli 6 stable and Tunear A has this problem. 

Anyway to fix it

 

 

 

[littlesat]

What problem?

[bledi07]

What problem?

AGC signal for some channels. Some have only 2% some 14% ans some channels have 98%

This channel has AGC 14%

 

 

[littlesat]

Why is that a problem? And by the way the value is delivered from the drivers. And not agc is not that important.

Edited by littlesat, 14 November 2017 - 00:05.

[bledi07]

Can that value be fixed in drivers to see correct AGC values.
Some channels have 98% some 2%

[Dimmie]

Drivers are made by the brand itself, so you should ask Air Digital/Zgemma for it.

[littlesat]

What is a correct agc....? It says nothing about the real signal. Actually it is subjective info

[bledi07]

Most of channels have AGC signal 98%.
So why some channels have AGC 2% or 10%. Why this difference?

[bledi07]

However due to this issue i am going to install another image like Open Atv or Egami and see if this issue continues.

[WanWizard]

You better spend some time to find out what AGC actually is, so you know why it is not relevant. Start with reading https://en.wikipedia...ic_gain_control

[littlesat]

However due to this issue i am going to install another image like Open Atv or Egami and see if this issue continues. 

Sure you can try... but when they behave differently they made an 'if box is x then do y' in their code... an additional feature from these kind of images that does not motivate the manufactures or driver makers to do it properly. While saying this I have the 'gut feeling' I feed some trolls...

[Erik Slagter]

Even then, what would one do with the "corrected" AGC value?

TS what are doing with it? Why would we spend effort on it?

[mimisiku]

This is ridiculous! AGC stands for A uto atic G ain C ontrol. It's a way of amplifying poor signal to a state the tuner can use. In fact, in an ideal situation AGC should be 0 (meaning no attenuation needed). An AGC of 100% would mean maximum attenuation possible. In other words it MAY be just a problem on the user's side. Poorly alligned dish, skew error etc..

[MCelliotG]

This has been extensively discussed before. The only actual and useful tuner values are SNR and that must be in db, not a non-sensical percentage (Zgemma H52S has a Silabs tuner, so it's perfect in this department) and BER. It's a common (and bad) practice that AGC is customarily used in skins (no reason why, it just happens), it means absolutely nothing, it changes between tuners and among different installations.

Now, OpenPLI only reports what the drivers give back, nothing to be fixed on their side.

[Erik Slagter]

This is ridiculous! AGC stands for A uto atic G ain C ontrol. It's a way of amplifying poor signal to a state the tuner can use. In fact, in an ideal situation AGC should be 0 (meaning no attenuation needed). An AGC of 100% would mean maximum attenuation possible. In other words it MAY be just a problem on the user's side. Poorly alligned dish, skew error etc..

To match the expectations of the users many manufacturers (maybe all) already revert this value, where 100% means max signal strength, minimal gain.

 

Anyhow, I can only stress that the strength of the signal, is totally irrelevant. Every signal, only if the quality is sufficient, can be amplified or attenuated to a usable level. That's what AGC is about. So only the quality is relevant and that's SNR (well, at least for the quality reduction it may be suffered on the way, if the signal was already foobar when transmitted, the SNR may be misleading).