[opendtv] Re: Spectrum Use for Broadcasting

Ron;

I'm not real familiar with this stuff.  I do know that taboos were
"loosened" a bit in major markets to permit analog and digital at the same
time.

The best way to limit much intermod issues is to co-locate transmitters,
since the interference overlap, and the relative difference between signal
levels is effectively the same in that zone.

We have a few interesting issues here in the southland.  KUSI-DT San Diego
and KSCI-DT will both -- post transition -- be operating on Channel 18.
(KUSI-TV is on 51)  They're about 115 or so miles apart.  Significant
portions of each station's Grade B contours overlap.  KSCI's programming is
mostly Korean (or was the last time I watched, and KUSI is in English.  The
areas between are heavily cabled, and has a low percentage of
Korean-speakers.

Qualcomm will be operating MediaFLO on channel 55 hearabouts, but KDOC-DT
(56) has agreed to accept interference from them.  KFMB-DT was operating on
55, but they are now hunting for a new channel before analog ceases.  They
even turned off their digital transmitter so Qualcomm could demo MediaFLO
during their annual meeting.   An awful lot of money will be spent finding a
VHF channel for KFMB-DT to operate on so that they can co-exist with
MediaFLO before Feb 17 next year.  (They will retain their analog channel 8
post-transition.)
 
I also tended to understate the effect of analog taboos.  -7 is 55 miles
between full service stations.  +14, IIRC, is 75 miles.  That's just a few
dozen miles less than the co-channel situation vis-à-vis KUSI/KSCI.  Analog
co-channel separation between full-service stations is 175 miles.

So, while you will have more slots open in SF post-transition, the
surrounding areas will have much more RF slots available than they do now,
because the digital "wedding cake" is much smaller than the analog one.  

We could, of course, read the original report and order, but that is 'almost
history' now.

John



-----Mensaje original-----
De: opendtv-bounce@xxxxxxxxxxxxx [mailto:opendtv-bounce@xxxxxxxxxxxxx] En
nombre de Ron Economos
Enviado el: Wednesday, February 27, 2008 5:55 AM
Para: opendtv@xxxxxxxxxxxxx
Asunto: [opendtv] Re: Spectrum Use for Broadcasting

I believe the digital taboos do not apply if the stations are co-located.
Here in the SF Bay Area market, there are plenty of 1 and 2 channel
offsets, but almost all the stations originate from one point, Sutro Tower.

Here's the current list of occupied channels:

2 analog (Sutro) KTVU
4 analog (Sutro) KRON
5 analog (Sutro) KPIX

7 analog (Sutro) KGO
9 analog (Sutro) KQED
11 analog (Mt. San Bruno) KNTV
12 digital (Mt. San Bruno) KNTV-DT

14 analog (Mt. Allison) KDTV
19 digital (Sutro) KBWB-DT
20 analog (Sutro) KBWB
24 digital (Sutro) KGO-DT
26 analog (Mt. San Bruno) KTSF
27 digital (Mt. San Bruno) KTSF-DT
29 digital (Sutro) KPIX-DT
30 digital (Sutro) KQED-DT
32 analog (Sutro) KMTP
33 digital (Sutro) KMTP-DT
34 digital (Sutro) KFSF-DT
36 analog (Monument Peak) KICU
38 analog (Sutro) KCNS
39 digital (Sutro) KCNS-DT
41 digital (Mt. San Bruno) KKPX-DT
43 digital (Sutro) KCSM-DT
44 analog (Sutro) KBCW
45 digital (Sutro) KBCW-DT
48 analog (Mt. Allison) KSTS
49 digital (Mt. Allison) KSTS-DT
50 digital (Monument Peak) KTEH-DT
51 digital (Mt. Allison) KDTV-DT
52 digital (Monument Peak) KICU-DT
54 analog (Monument Peak) KTEH
56 digital (Sutro) KTVU-DT
57 digital (Sutro) KRON-DT
65 analog (Mt. San Bruno) KKPX
66 analog (Sutro) KFSF

Plus a few more out of market stations receivable.

Pretty well packed right now. 35 out of 67, or 52%.

KCSM is digital only, so that's the reason for the odd number.
Actually, they have a transmitter on 60, but it's just a few
hundred watts and not receivable unless you're on the campus.

After the transition:

7 digital (Sutro) KGO-DT
12 digital (Mt. San Bruno) KNTV-DT

19 digital (Sutro) KBWB-DT
27 digital (Mt. San Bruno) KTSF-DT
29 digital (Sutro) KPIX-DT
30 digital (Sutro) KQED-DT
33 digital (Sutro) KMTP-DT
34 digital (Sutro) KFSF-DT
36 digital (Monument Peak) KICU-DT
38 digital (Sutro) KRON-DT
39 digital (Sutro) KCNS-DT
41 digital (Mt. San Bruno) KKPX-DT
43 digital (Sutro) KCSM-DT
44 digital (Sutro) KTVU-DT
45 digital (Sutro) KBCW-DT
49 digital (Mt. Allison) KSTS-DT
50 digital (Monument Peak) KTEH-DT
51 digital (Mt. Allison) KDTV-DT

18 out of 49, or 37%

Ron

John Willkie wrote:

>Pshaw.  You are singularly misinformed on RF issues.
>
>Here's the analog UHF taboos:
>+/- 0
>+/- 1
>+/- 2
>+/- 3
>+/- 4
>+/- 5
>+ 7
>- 14
>- 15
>
>That is, you have to protect existing channels by those channel offsets.
>There's a hole every six channels.
>
>Here's the digital UHF taboos
>
>+/- 0
>+/- 1
>+/- 2
>
>There are holes starting at three channels off.  And, the interference
>protections are much lower than with analog.
>
>And, we can see this in effect even now, as "for the most part" LPTV/tv
>translator stations can now operate using the NEW taboos, and there are
>many, many more channels now permitted for LPTV and tv translator use in or
>near major cities than there were previously.
>
>John Willkie
>  
>
 
 
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