[opendtv] Re: Integrated DTV PSIP
- From: Bob Miller <bob@xxxxxxxxxx>
- To: opendtv@xxxxxxxxxxxxx
- Date: Fri, 02 Dec 2005 12:53:07 -0500
Doug McDonald wrote:
>John Shutt wrote:
>
>
>
>>>The antenna pointing problem has to be solved even for
>>>recording devices. Meaning, not solved with rotors, IMO.
>>>In principle, that also applies to the analog time
>>>service from PBS. It seems fairly robust, but I'm sure
>>>it too has its limits.
>>>
>>>
>>The ideal situation is to be able to use omnidirectional antenna. Unless
>>you are in a very rare situation where you are way out in the boonies
>>between two major markets and can only receive signals with a huge mast
>>mounted antenna, an omni antenna with preamp if necessary should suffice.
>>
>>
>
>JOHN: let's be blunt: TALK ABOUT WHAT YOU KNOW ABOUT.
>
>I'm not in the boonies. I'm in the city. We have major stations in
>two directions, and soon to be three (now w and ene, soon to be s too).
>Despite being in a rather flat area, we do have some topography,
>and there are many places in town, including where I live, where
>you can get any Fox station with any existing omni antenna. Even
>in the best places it's iffy. PERIOD. In the good places it's
>perfectly easy to get all stations with a good BI-directional
>quad bowtie, such as any commercial one with the reflector
>cut off ... but there are NO commercial antennas which will
>get all networks reliably in an attic or on a very low
>roof, unmodified. What people are using is two antennas with two
>downleads. The problem, on a roof or attic, is NOT
>MULTIPATH, it is signal strength of the Fox channels.
>I know what I speak about, since I have now gone around
>with a spectrum analyzer measuring things. Using the two antennas
>solution the "wrong antenna" indeed has terrible multipath, but even
>then the newer STBs usually work just fine IF THERE IS PLENTY
>OF SIGNAL. But usually, except for one station, when there
>is bad multipath, the absolute signal strength is TOO LOW.
>
>Now I suspect that a PROPER omni antenna, mounted well off the
>roof, would work fine ... but even the nearest Fox would be a
>problem in many places unless it were an 8-bay antenna. AND NOBODY SELLS
>EVEN FOUR BAY ALL-UHF BAND OMNI ANTENNAS. I've tried designing such
>things and failed. It's not easy to get them all phased so that
>it remains omni over the whole band. We have UHF channels from 18 to
>48, soon also a 50, and they will remain after analog turnoff. There is
>also a VHF Ch. 9, but it's close and easy to get.
>
>Now if the closest Fox were on a 1000 foot tower instead of
>about 480 feet, things would be mighty different. But it's not.
>There are other Fox's available, but they are equally weak,
>at best.
>
>And we are NOT "between markets" ... we are fairly close to the
>center of ours.
>
>Doug McDonald
>
Doug,
Do a search on Ebay for "Freeview". See all the omni antennas being sold
with Freeview antennas for the UK where the highest transmitter power is
20 kW ERP and the average power for a transmitter has to be like 3 kW.
They seem to be selling a lot of simple omni antennas for both mobile
and fixed reception there even though they have the old 2K COFDM.
Bob Miller
----------------------------------------------------------------------
You can UNSUBSCRIBE from the OpenDTV list in two ways:
- Using the UNSUBSCRIBE command in your user configuration settings at
FreeLists.org
- By sending a message to: opendtv-request@xxxxxxxxxxxxx with the word
unsubscribe in the subject line.
Other related posts: