I learned this the hard way and he’s right.
On Mon, Jul 26, 2021 at 12:18 PM Richard Goetz <rickg@xxxxxxxxxxxxxxxxxx>
wrote:
Something that surprises me is station owners that ask me why
businesses will not buy advertising from them. First question, are you on
cable. Most of the time, “No”. 2nd question is have you ever checked to
see what it takes to light up Rabbit Ears in your own home as a starting
point. Normally I hear “No” which tends to also surprise me since that is
what your viewers and advertisers are doing. So let’s again look at that.
Yes, maybe 3-5% of the homes have outside antennas. But the majority of
“Cord Cutter” are using rabbit ears. I recently did an article and used my
office as an example. Real simple test. Buy cheap rabbit ears from the
local “Wal-Mart” type of store, connect them up and scan for channels. Same
thing your viewers would do. Then go to TVFool.com and run a study at your
address. Here is what it was for my house.
Call Sign RF Channel Quality dBm (From TVFool)
WKRN 27 Break Up -29.5
WSMV 10 Solid -32.5
WTVF 5 Solid -31.0
WZTV 15 Solid -28.3
WKUW 40 Break Up -42.7
Now to convert dBm to dBu. I won’t bore you with the formula from TV
Technology but the break down is:
UHF 14-36 dBu=129.70 +dBm
VHF 07-13 dBu=120.87 + dBm
VHF 02-06 dBu=111.84 + dBm
Since dBm are minus, we are actually subtracting it from the fixed
amount.
WKRN was breaking up at -29.5 dBm, so 129.70 – 29.5 = 100.2 dBu, so we
need it to be higher since it was breaking up.
WZTV was solid at -28.3, so 129.70 -28.3 = 101.4 dBu, so in my office,
it takes around 101 dBu for a solid signal.
Whoa, what happened to the 48 dBu the FCC says is the City Grade level.
Well that values is based 30’ in the air, clear line-of-sight. A really big
TV stand outside. The point here is adversities do not want to advertise on
a station they cannot pick up and requires the people at home to put up an
outside antenna. They want you to pull a small TV out of your pocket, turn
it on, and see your station.
As a disclaimer, years ago I did the study in various parts of my house
and came up with 50% of the rooms requiring 77 dBu for UHF, 70 dBu for high
band VHF and 60 dBu for low band VHF. But also keep in mind rabbit ears
today are made for UHF and there is a lot of loss in picking up VHF, so use
the 80 dBu for all channels.
Do the test for yourself and let know on here what you find. Have a
consultant make you a Longley Rice coverage map (We charge $50) and see
where you are. If you are on a big tower outside of town and the 80 dBu
does not make it to town, you may be better off on a 200’ tower in the
center of town. They are starting to allow LPTV to use Distributed
Transmission System or DTS where you have a bunch of small stations on the
same channel locked together. But those are very expensive at this time
unless you are in a town of 100,000 people and have a town 15 miles away
with another 100,000. Then it may make sense.
Richard Goetz
rickg@xxxxxxxxxxxxxxxxxx
615 826-0792
