[opendtv] Re: Tentative Channel Elections
- From: "Benham, Cliff" <Cliff_Benham@xxxxxxxxxxxxxxxxx>
- To: <opendtv@xxxxxxxxxxxxx>, <opendtv@xxxxxxxxxxxxx>
- Date: Fri, 7 Oct 2005 10:59:04 -0400
I went looking for 'Linx Testing' and found this after reading the piece =
for the previous month:
=20
From: RF Technology: Doug Lung =20
TV Technology 08.04.04
http://www.tvtechnology.com/features/On-RF/f_Choosing_a_Final.shtm
"Some channels can be eliminated immediately. [snip] Channels 2 through =
4, and likely Channel 5 as well will not be suitable for DTV in most =
markets due to antenna size and electrical interference. Channel 5 may =
work better, but if broadcasters avoid other low VHF channels, there may =
be little incentive for people to erect antennas for Channel 5. Channel =
6 will probably be unsuitable for DTV in most areas due to FM radio =
interference.
[snip]
WBBM-DT on Channel 3 in Chicago continued to generate a lot of comments, =
including some from CBS engineers. The two big problems people mentioned =
when talking about low VHF reception were picture break-up due to =
impulse noise and the need for a large outside antenna.=20
Jim Steffey, director of engineering for WWMT-DT, Channel 2 in =
Kalamazoo, Mich., said that even though the station is operating at its =
full authorized power, "During thunderstorms, the signal becomes totally =
unwatchable with frequent pauses in the audio and heavy pixelation and =
picture freezes."
Power line noise is also a problem. He noted that upper VHF and UHF DTV =
stations in the same market can be received "without any trouble at all, =
with not much more than a coat hanger for an antenna."
[snip]
Larry Davis, the transmitter supervisor at WBBM-TV/DT, said that the =
signal is receivable in the market, provided you have an outdoor =
antenna. The need for an outdoor antenna to receive low VHF when an =
indoor Silver Sensor works fine on the other channels is a problem.=20
[snip]
Pete Putman, a DTV consultant who has a wealth of information on his =
Web site at http://www.hdtvexpert.com said low VHF DTV is not a good =
idea due to impulse noise and e-skip.=20
[snip]
Philip Smith wrote to mention problems he was having receiving WBBM-DT. =
At 46 miles from downtown Chicago where WBBM has its antenna, his =
reception using conventional antennas was similar to the others I've =
mentioned. What I found interesting was his experience with a USB-2.0 =
based DTV tuner and a laptop.=20
I've always wanted one of those to check out DTV reception as I travel =
from market to market. However, the electrical noise from the tuner and =
computer seemed to be creating RFI (radio frequency interference) that =
interfered with low VHF DTV reception. The USB 2.0 tuner is made by =
Sasem in Korea and is supposed to use the "latest" LG Electronics =
(Zenith) 8-VSB demodulator chip. More information is available at =
www.sasem.com =20
=20
This is about the only piece I could find on low VHF DTV.=20
I think some more testing needs to be done over the next 2 years=20
=20
________________________________
From: opendtv-bounce@xxxxxxxxxxxxx on behalf of Mark Schubin
Sent: Fri 10/7/2005 9:55 AM
To: opendtv@xxxxxxxxxxxxx
Subject: [opendtv] Re: Tentative Channel Elections
I think WBBM-DT in Chicago (channel 3) was part of the Linx testing.
TTFN,
Mark
Benham, Cliff wrote:
>I don't recall reading anywhere that testing of 8VSB DTV at low VHF =3D
>frequencies has been done, or if it has,
>what the results were. We have all read about 8VSB/COFDM testing that =
=3D
>was done at UHF frequencies, but
>where are the test results for 8VSB at low VHF? This seems to be an =3D
>accident waiting to happen, and one that=3D20
>in the Philadelphia area will be bad both for ABC and all the =3D
>disenfranchised viewers the day after analog shutoff.
>
>________________________________
>
>From: opendtv-bounce@xxxxxxxxxxxxx on behalf of Manfredi, Albert E
>Sent: Thu 10/6/2005 4:28 PM
>To: opendtv@xxxxxxxxxxxxx
>Subject: [opendtv] Re: Tentative Channel Elections
>
>
>
>Cliff wrote:
>
>=20
>
>>A channel 6 rabbit ear antenna is about 60 inches
>>wide. At my house I would have to set the antenna
>>direction so one 'ear' is sticking about 3 feet
>>out into the living room and the other into the
>>hallway right at 'eye height'.
>> =20
>>
>
>Cliff, I want you to know that I groaned when I saw
>that WPVI (Phila) decided to go back to their VHF
>Channel 6 allocation. I groaned because I remember
>how you worried someone might use VHF for DTT.
>
>Hey, for Channel 6, maybe you can use one of those
>Radio Shack "use your house wiring as an antenna"
>gizmos.
>
>Bert
>
>
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