At 08:13 PM 02/15/09, you wrote:
On Sun, 15 Feb 2009, Chuck Kelsey wrote:
> Check here:
<http://www.fcc.gov/dtv/markets/>http://www.fcc.gov/dtv/markets/
Supposedly, the benefit to DTV is that it requires a tight filter mask,
so out of band interference should be minimized.
But you still have intermod and mix between carriers,
and the DTV signal looks like a solid block on the
spectrum analyzer.
And it gets worse if you have multiple transmitters.
For an example of a worst-case scenario, lets
look at the Los Angeles marketplace (i.e. the
stations I can see from my location using a
good antenna) after the switchover:
The three columns are callsign, old channel
and new channel
KABC 7 7
KCAL 9 9
KTTV 11 11
KCOP 13 13
KSCI 18 18
KTBN 40 23
KVCR 24 26
KCET 28 28
KFTR 46 29
KTLA 5 31
KDOC 56 32
KMEX 34 34
KRCA 62 35
KNBC 4 36
KPXN 30 38
KVEA 52 39
KLCS 58 41
KWHY 22 42
KCBS 2 43
KAZA 54 47
KOCE 40 48
KJLA 57 49
KXLA 44 51
We are going to have a solid block of DTV energy
from channel 31-36 (from 572 to 608 MHz), and
that does not count the other stations.
The only reason that 37 is unoccupied is that it's
reserved for radio astronomy.
I think that the existing multi-microvolt UHF noise
floor is going to get worse, and the mix products
are going to go through the roof.
But for the first time in my lifetime 6m will get
better - channels 2, 4, and 5 are going off the
air (until the FCC sells that spectrum).
Maybe we can put a 6m repeater on the
channel 2 tower? It's 970 feet tall on top
of a 5,000 foot mountain, and the chief
engineer is ham-friendly...
Mike WA6ILQ
