Transition issue with broadcast antennas?

1187 Views 8 Replies 4 Participants Last post by n3ntj, Sep 9, 2008

n3ntj

Discussion Starter · Sep 6, 2008

Something I was thinking of last night..

Some channels are changing to a new digital freq when the changeover occurs. For example, a station is currently on analog channel 10 and currently digital on channel 67. When the switchover happens, they are going digital to channel 34. A good example of this is WCAU channel 10 (10.1) out of Philly.

That would mean that they'd currently have two antennas in service (one for 10 and one for 67). Not sure how broadband the UHF broadcast antennas are, but when they make the change from 67 to 34, what physically will need to be done?? Will they be able to retune the current 'digital' antenna/system at the transmitter for use on channel 34 or will they need to install a new tuned antenna for use with channel 34?

Theoretically, they could end up with having 3 antennas up the tower.. the old one used for analog, the current one for digital, and the new tuned one for post-transition digital.

Just a little curious..

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Stewart Vernon

· #2 · Sep 7, 2008

A lot would depend upon the type of antenna in use and how they need to tune it.

If the antenna is good for a certain range and can be retuned, then maybe they just need to do that. If the antenna can be retuned, but only lower (i.e. physical bits have to be hacked off to tune) then a station might only be able to retune if they are going to a lower channel number.

For the handful or so stations that will revert to their old analog frequency (be it UHF or VHF) then they already have an antenna in place that might be perfectly fine.

I suspect it will be a mixed bag... but fortunately the antenna itself really should be the least expensive part of the transition.

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n3ntj

Discussion Starter · #3 · Sep 8, 2008

HDMe said:
A lot would depend upon the type of antenna in use and how they need to tune it.

If the antenna is good for a certain range and can be retuned, then maybe they just need to do that. If the antenna can be retuned, but only lower (i.e. physical bits have to be hacked off to tune) then a station might only be able to retune if they are going to a lower channel number.

For the handful or so stations that will revert to their old analog frequency (be it UHF or VHF) then they already have an antenna in place that might be perfectly fine.

I suspect it will be a mixed bag... but fortunately the antenna itself really should be the least expensive part of the transition.

Yup, for the example above, we're going from near 790 MHz (67) to approx. 590 MHz (34). All depends, how broad band the equipment is. Also, when this channel change happens, are station engineers going to be up all night retuning (where needed) for the official post-transition freqs?

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Stewart Vernon

· #4 · Sep 8, 2008

n3ntj said:
Yup, for the example above, we're going from near 790 MHz (67) to approx. 590 MHz (34). All depends, how broad band the equipment is. Also, when this channel change happens, are station engineers going to be up all night retuning (where needed) for the official post-transition freqs?

I expect a mixed bag of problems when the massive cutover happens.

In my area, for example... We have one station on 27 (28.1) and another at 57 (22.1), but in Feb 28.1 will go to its analog 28 channel and 22.1 will go to 27... Both stations are owned by the same company (Sinclair), but this means that all of a sudden 22 and 28 analog have to stop while 27 moves to 28 and 57 moves to 27. Any number of things could happen if they aren't able to do any advance testing that could render both channels down while they fix.

Maybe it will all go perfect, but who knows. Several other channels in the area are changing around too, and at least one other is going back to its analog frequency in the VHF band.

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Scott in FL

· #5 · Sep 8, 2008

n3ntj said:
Not sure how broadband the UHF broadcast antennas are...

UHF (and VHF) panel antennas are very broadband. Here's one from ERI:

http://www.eriinc.com/pubs/Catalog07_080-081.pdf

That said, they're also pretty expensive. They're meant to be shared by several stations. That may be what's happening. Instead of one station buying a very expensive antenna that will work for both of their channels, the UHF stations in your market may be diplexing into one panel antenna. This is very common.

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scooper

· #6 · Sep 8, 2008

HDMe said:
I expect a mixed bag of problems when the massive cutover happens.

In my area, for example... We have one station on 27 (28.1) and another at 57 (22.1), but in Feb 28.1 will go to its analog 28 channel and 22.1 will go to 27... Both stations are owned by the same company (Sinclair), but this means that all of a sudden 22 and 28 analog have to stop while 27 moves to 28 and 57 moves to 27. Any number of things could happen if they aren't able to do any advance testing that could render both channels down while they fix.

Maybe it will all go perfect, but who knows. Several other channels in the area are changing around too, and at least one other is going back to its analog frequency in the VHF band.

Yes - our market is one of the more active about channels hopping around on Feb 17

. All I got to say is if you rely on OTA , rescan frequently around that time .

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n3ntj

Discussion Starter · #7 · Sep 8, 2008

I just hope D* has all of the changes in their software, so next Feb 19th, the IRD's know to look for the new info (about the channel changes, where needed) on the OTA ATSC tuners. Otherwise, the unit may be looking at the old pre-transition digital channel freq (67) and not the new one (34), even though the PSIP will still say 10.1.

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Scott in FL

· #8 · Sep 9, 2008

n3ntj said:
I just hope D* has all of the changes in their software, so next Feb 19th, the IRD's know to look for the new info (about the channel changes, where needed) on the OTA ATSC tuners. Otherwise, the unit may be looking at the old pre-transition digital channel freq (67) and not the new one (34), even though the PSIP will still say 10.1.

From my (limited) experience with locals on D* and that other satellite company, here's how things are set up. D* has an agreement with a communications company in each market. The two that I have seen are satellite teleports near Baltimore and Miami. TV antennas at those locations pick up the OTA signals for that city and send them to D* via satellite or fiber. I don't think there are any local tv stations that fiber their signal directly to D*, but I may be wrong. Things change, especially with HD, and the last time I was at one of these facilities was Miami in 2005.

Anyway, my point is, it's not D* that must retune all of the OTA tuners in February. The local company will send a technician out who will have to retune only 6 or so tuners. So hopefully things will go smoothly.

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n3ntj

Discussion Starter · #9 · Sep 9, 2008

Key word is "hopefully".

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