[mythtv-users] DVB-T Cards - Comparisons or experiences

[mike choy]

Stephen Kitchener wrote:
> On Friday 03 Feb 2006 19:05, mike choy wrote:
>   
>> Stephen Kitchener wrote:
>>     
>>> On Friday 03 Feb 2006 16:50, Dan Seddon wrote:
>>>       
>>>> Stephen Kitchener wrote:
>>>>         
>>>>> Hi List,
>>>>>
>>>>> I need some expert advice please.
>>>>>
>>>>> I am trying to decide as to which DVB-T card to buy, I have a list
>>>>> (though there are probably more) to select from, but I need someone who
>>>>> has had the experience, to answer a simple question....(the answer
>>>>> might not be simple however)
>>>>>
>>>>> The list is :-
>>>>> the list comes from " "http://pvrhw.goldfish.org/tiki-pvrhwdb.php"
>>>>>
>>>>> Twinhan Visionplus DVB-T
>>>>> Wintv Nova-T
>>>>> Technotrend Budget DVB-T
>>>>> Kworld DVB-T Xpert PCI
>>>>>
>>>>> (these are the ones that I could identify as DVB-T)
>>>>>
>>>>> Now I think that the Technotrend Budget DVB-T is the same as the Wintv
>>>>> Nova-T, which I already have, and isn't very good at decoding.
>>>>>
>>>>> The question is, which card is better at reception, I'm not talking
>>>>> about speed of tuning, I can compensate for that in the recording
>>>>> profiles if needed, what I am asking is which card is more sensitive or
>>>>> better at decoding the digital stream ??
>>>>>           
>>>> I'm a bit confused here, though you might be answering some questions
>>>> which I've wondered. When you mean decoded - I'm guessing you're talking
>>>> about turning the recieved transmission in to an Mpeg stream? As, the
>>>> actual decoding of the mpeg is done in software or hardware (which ever
>>>> you use). So, by saying some cards are better than others at decoding,
>>>> do you mean that some a more reliable/faster at converting the signal
>>>> (so you have fewer artifacts and quicker channel changes on Live TV) -
>>>> as the actual image quality would be determined by the mpeg decoder? I
>>>> have 2 Nova-T cards,  as they seem to be the best supported, and
>>>> sometimes get freezing and artifacts (which I guess could be down to the
>>>> card), but they are definietly very slow at changing channels. You seem
>>>> to be saying this varies from card to card - or are you hoping it might
>>>> do? I would certainly like my channels to change quicker (though perhaps
>>>> that will be improved in 19.0), I hadn't thought of these issues being
>>>> card dependent before.
>>>>         
>>> Sorry I wasn't specific enough...what I meant was that some cards seem to
>>> be better at getting a usable signal from the transmitter before it gets
>>> decoded into a digital stream and that is down to the sensitivity of the
>>> tuner on the card, its ability to get a signal from the transmitter and
>>> not down to the ability of the encoders on the card.
>>>
>>> If the signal isn't good enough as it leaves the tuner, you will get
>>> artifacts and there isn't anything that you can do about it.....Unless
>>> someone knows better, I would like to know.
>>>
>>> As to card switching speeds, I would suggest that is down to the
>>> hardware, and not at all down to Mythtv, maybe the firmware, but then
>>> that has to talk to the hardware anyway...
>>>
>>>       
>>>> Thanks
>>>>
>>>> Dan
>>>>
>>>>
>>>>
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>>>       
>> Off all the cards you have there the K-World is the better card
>> it uses the newer conexant chip and seems to produce a cleaner picture.
>>
>> However you might consider the new Freecom DVB-T USB  it is very very
>> sensitive
>> and if you are using any sort of amplifier in your house you will
>> actually need to add an attenuator.
>>
>> Have a look here
>> http://acaciaclose.co.uk/16253/index.html
>>     
>
> Looks ok, wonder if I can run more than one in the same pc......
>
>   
>> However nothing ever substitutes a high quality aerial, high quality
>> downlead when it comes to digital tv.
>>     
>
> I have all that, it's just the disparity with the abilities of the set-top 
> boxes, where they can get all the channels with no problem and the PCI cards 
> where the one that I have at present, the NOVA-T, where it has difficulty in 
> resolving the picture. The same antenna system feeds both set-top boxes and 
> the PC pci card....
>
> Maybe it's the more hostile environment inside a PC, ie there's more generated 
> interference there, that is getting in the way...if there were a way of 
> separating the card from the PC somehow, it might be different, but I don't 
> see how, so a more sensitive card, one that has a better signal to noise 
> ratio, should help, though that might not help as it could just be better at 
> receiving the PC noise and not the TV signal :-(, though the PC noise should 
> be out of the TV bands.
>
> As you say, a good Antenna and really good aerial downlead is essential. 
>
> It's not the quantity of signal that will fix things its the quality that 
> counts. I accept that there must be enough signal, but getting more signal 
> though an amplifer won't help, because the amp will amplify the noise floor 
> at the same time as it amplifies the signal and the amp will itself add more 
> noise to the signal....
>
> Oh well, all I can do in the end is to try one and see I guess...short of 
> having some measuring equipment to see what is really happening.
>
>   
>> Mike C
>>
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>
>   
You can have as many of the freecoms as your system can cope with.

Its very good when its good, crystal clear picture and nice smooth motion

Mike C