addenda: it's not uncommon to have the antenna hooked up to a LNB that downconverts to broadcast channels, so I guess technically, you don't need a STB.  I forgot about that wrinkle.  When I was active in the field, LNBs were just on the market and hadn't yet gotten to non-satellite frequencies.

John Willkie

-----Original Message-----
From: dan.grimes@xxxxxxxx
Sent: Jun 24, 2008 1:00 PM
To: opendtv@xxxxxxxxxxxxx
Subject: [opendtv] Re: ITFS

Were all at 2.4 GHz? I'm almost sure ours used a UHF antenna (although perhaps had a higher frequency response) and the tuner was 450Mhz tops. But there was a box just below the antenna which may have downconverted the frequency. I just thought it was an amplifier. Its still up there so perhaps I'll go check it out sometime.

Dan

John Willkie <johnwillkie@xxxxxxxxxxxxx>

John Willkie <johnwillkie@xxxxxxxxxxxxx> Sent by: opendtv-bounce@xxxxxxxxxxxxx 06/24/2008 10:37 AM Please respond to opendtv@xxxxxxxxxxxxx

To opendtv@xxxxxxxxxxxxx cc Subject [opendtv] Re: ITFS

The disadvantages of ITFS is that you can't just go down to the BestBuy to get a receiver; you need a STB, etc, and the 2.4 Ghz frequencies aren't the best for penetrating walls; most systems use an external parabolic reflector, the smallest being about the size of a Dish/DirectTV unit. (I've even seen smaller units here and there, looking like a flattened couch pillow.)

There are advantages. You can use any modulation system you desire, even rolling your own. You can flexibly re-allocate channels (there are some FCC limits having to do with the mission of the licensee.) Also, you can employ wireless "response channels."

And, yes, there are many, many ITFS/MMDS (Multichannel Multipoint Distribution System)/OFS (operational fixed systems) in use around the country. Many are used for data distribution in addition to tv systems.

Dave Schmitt, who hasn't posted here for quite some time, designed and built the ITFS system operated by the Diocese of Los Angeles, which I believe is the largest in the world.

John Willkie