13 May
2013
13 May
'13
4:18 p.m.
Thanks, Dan. That helps a lot. Is there something about the DVB-S modulation that makes it astoundingly better for this application? For something that is intended to be widely received, they sure are making it difficult... Greg. KO6TH
--
Sent from my new toy... Please ignore tupos.
Daniel Schultz n8fgv@usa.net wrote:
>------------- Original Message -------------
>>> Right. But what is that in terms of what normally gets described?
>>> For example, I have a Digital TV card for my computer (Pinnacle PCTV
>
>>> HD). It says it does "ATSC digital TV (HDTV up to 1080i, and SDTV)"
>
>>> and "Clear QAM (unencrypted digital cable)".
>>>
>>> Am I even close?
>>>
>>> Greg KO6TH
>
>No, you are not even close.
>
>ATSC (Advanced Television Systems Committee) is the proprietary
>over-the-air
>television broadcast standard used in North America. It is
>fundamentally
>incompatible with the open source "DVB-T" broadcast standard that the
>rest of
>the world uses for domestic TV. (The fact that it was designed by a
>committee
>should tell you all that you need to know about that particular
>political
>sausage.) The "Cheap and Easy SDR" article in January QST requires
>using a
>DVB-T USB dongle which you need to purchase from a supplier that knows
>that
>you want to use it for SDR. The ATSC USB devices sold at Best Buy or
>other
>retail stores in the USA cannot be used for this purpose.
>
>QAM is used only by cable TV and is never broadcast over the air. (Most
>cable
>systems use encrypted QAM so you will still need to rent the decoder
>box from
>the cable company).
>
>DVB-S is the digital satellite TV standard that the "free to air" (FTA)
>satellite receivers use. We are not talking about Direct TV or Dish TV,
>but
>the C band services. If you watch NASA TV or the foreign language TV
>broadcasts directly from your C band dish, you are using DVB-S. This
>standard
>has been used for terrestrial ham ATV in some US cities. It would be
>best to
>contact the ATV experts directly to see what receivers they are using.
>I don't
>know which FTA receivers will work with the ISS ham TV.
>
>Bottom line is: ATSC and QAM decoders are not useful for receiving the
>ISS ham
>TV signals, and DVB-S is not widely used in the USA except by dedicated
>"free
>to air" hobbyists. If you bought your receiver card or dongle from any
>US
>consumer retail store, it almost certainly is not what you need for ISS
>ham
>TV.
>
>Dan Schultz N8FGV