SNR for DVB-T

[stick50jr]

Currently the SNR for DVB-T tuners is displayed as zero on Vix images... (at least on my Vix 2.2.106).

Is this worthy of some effort to fix? It would be nice to know what is happenning in this respect. I find the AGC number to be a bit confusing and it doesn't seem to correlate with good nor weak reception.

I know you've got plenty to work on but I am aware that the BH image does display non-zero SNR.

I still prefer to use the Vix image because it is better in so many other ways.

Cheers from down under

[stick50jr]

Is the problem of displaying 0 (zero) for SNR when using DVB-T caused by a Vix issue or is it caused by an OpenPLi or a driver issue.
Presumably, I should be asking about this problem in different forums if it is not one that Vix (Andy) has an interest in?

cheers

[Larry-G]

SNR
AGC
BER

are values given to satellite signals, now i may be wrong but i would have though that they would have nothing what so ever to do with DVB-T reception as it uses a different method of receiving the signals ie a tv Ariel instead of a satellite dish and LNB and yes for the reocrd this is the home forum of VIX and andy

[stick50jr]

@Pheonix,

Thanks for your reply.

DVB-T & DVB-S

However, DVB-T like DVB-S is rf and digital. So regardless of whether one uses a dish with an lnb or an aerial, you'll still need to receive the rf signal. There will still be AGC to moderate the strength of the gross signal into the front end of the receiver. When the signal is processed by the receiver, it will still be possible to compare the signal to the noise (SNR). And when the signal is demodulated/digitised, there will also be a Bit Error Rate (BER). In short, the process is very similar to DVB-S. The rf frequencies used are much lower in the case of terrestrial transmissions, and this obviates the need to have an lnb.

BER, SNR & AGC

Anyway, the BER should hopefully be zero if you have good reception. Anything non zero is a concern, even though some small BERs can be corrected or may have only a minor impact on the viewed picture.

The SNR is the best comparative measure of reception quality and is the thing we want to maximise when setting up our antenna, distribution cabling and receiver. This is the parameter that is missing from Vix but is available from some other images (eg. BH)

The AGC figure is indicative of the gross rf signal power, but a large or small number does not indicate the quality of the signal and it doesn't indicate whether you should expect a good error free picture. The parameter is displayed by Vix (but is of less interest than the missing SNR).


I hope I'm not telling you how to suck eggs but from my understanding you will see that the SNR and BER are the parameters of choice in this scheme of things. So my question remains:

Is the SNR for DVB-T devices going to be fixed within Vix or is it outside of Vix and should I pursue this problem with OpenPLi or device driver people?


Thank you and especially your one man coding team for providing the best image around for this Vu+Duo. I'm currently running Vix 2.2.109 with two embedded satellite tuners and a dual terrestrial tuner usb stick, HauppaugeTV-Nova-TD. These four tuners work well and the Duo is often asked to record many programs simultaneously (which it happily does). Digital terrestrial transmissions have just begun in my part of the world and the broadcasters have had a few teething issues. I like to follow the terrestrial signal quality in order to help me decide whether my system is okay or whether the broadcasters have been stuffing us around again!

May I also compliment on the board update... nicer default colours and great to have my '.jpg' file visible.

Cheers from a sunny and dry place.