[amsat-bb] Re: ISS HamTV Frequencies

[Daniel Schultz]

------------- 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