Going back to existing channel numbers after 2009?

[luvdtv04]

I've read in other places that after 2/2009, the -DT channels will move to their current analog counterparts. For instance, channel 12 in my area is currently broadcasting their DT signal on channel 54. After 2/2009, is it true that their DT signal will move to channel 12, and if other channels do this as well, how does this free up any of the VHF spectrum? Or is this just a PSIP thing?

[HIPAR]

I've read in other places that after 2/2009, the -DT channels will move to their current analog counterparts. For instance, channel 12 in my area is currently broadcasting their DT signal on channel 54. After 2/2009, is it true that their DT signal will move to channel 12, and if other channels do this as well, how does this free up any of the VHF spectrum? Or is this just a PSIP thing?

I have also read those annoying press references to 'freed analog spectrum' that seem to foster a perception that DTV will move to the UHF channels so the Government can auction the 'freed VHF spectrum'.

My understanding is, when the transition occurs in 2009, stations that are currenty broadcasting analog on a VHF channel and are also broadcasting DTV on a 'loaned' UHF channel will still have the option to move digital operations to their VHF assignment and then vacate the UHF assignment. Many stations have already moved DTV operations to their VHF assignment.

Freed spectrum for auctions actually refers to UHF channels 52-69 in the 700 - 800 Mhz band. The DTV transisition is complicated because stations currently operating there must move to a channel below 52 after a 'loaned' UHF assignment has been relinquished.

A portion of the 'freed from TV spectrum' will be assigned for public saftey interoperability communications and the rest will be auctioned for use by various wireless services.

When it's over, channels 2 - 51 will still remain available for DTV. These channels will remain at their currently assigned frequencies.

--- CHAS

[luvdtv04]

Thanks! Most logical and straightforward explanation I've read yet. I appreciate it!

[KKlare]

I did not know they were going to cut that deeply to 52. I knew that they will/have removed all channels 70 to 83 from use. I thought that was to go to the 700 MHz cell phones but it could have been public service/safety. (800 MHz is the "older" cell phones and 900 MHz is for unlicensed devices like wireless phones just as 2300 is for cell phones and 2400 MHz is for unlicensed like 802.11. It is funny that they push use of the higher bands but, I think, the lower would have better distant reception but require longer antenna stubs.)
-Ken

[HIPAR]

The channels above 70 were deallocated from TV about 20 years ago. They were in the 800 - 900 Mhz band. Analog cell phones, pagers and computer controlled multichannel trunked systems now operate in that band.

There was a major debacle with the 800 Mhz band plan and its channel frequency assignments that resulted in major interference between many public safety trunked systems and the cell phone operations. The 800 Mhz spectrum is being 'rebanded' a great expense to correct the problems.

Some of the lower 700 Mhz band has already been auctioned. I don't know how the license winners are using it because incumbent TV stations still operate there and they are still protected by law from interference.

--- CHAS

[Link]

I don't really understand the UHF loaned digital channels. Like we get channel 7's digital signal on 7.1, 7.2, and 7.3 not any UHF channel and the other local stations are they same way.

[luvdtv04]

PSIP allows them to be "mapped" to 7.1, 7.2, 7.3, etc., but in actuality they are probably assigned to a UHF channel like 39.

[rboy177]

So if it is possible that some stations will go back to their VHF channels, would it be more advised to get a VHF/UHF OTA rather than just a UHF antenna?

[Geronimo]

So if it is possible that some stations will go back to their VHF channels, would it be more advised to get a VHF/UHF OTA rather than just a UHF antenna?


Yes.

[GravelChan]

So if it is possible that some stations will go back to their VHF channels, would it be more advised to get a VHF/UHF OTA rather than just a UHF antenna?


http://hraunfoss.fcc.gov/edocs_public/attachmatch/DA-05-2649A2.pdf

Is a list of TV stations, their current digital and analog channels and the
channel they have chosen to use for their digital broadcast when
analog is turned off.

[rboy177]

http://hraunfoss.fcc.gov/edocs_public/attachmatch/DA-05-2649A2.pdf

Is a list of TV stations, their current digital and analog channels and the
channel they have chosen to use for their digital broadcast when
analog is turned off.

Thanks for the list...that is very helpful.
It seems as if the Los Angeles Market is about 50/50 on if they are going to stay UHF or go back to VHF.

[GravelChan]

Thanks for the list...that is very helpful.
It seems as if the Los Angeles Market is about 50/50 on if they are going to stay UHF or go back to VHF.

You're welcome, I think you will find the majority of the stations transmitting analog on lower VHF (2-6) will stay with the digital frequency and those currently analog on higher VHF (7-13) will go back to this rf channel for digital. I have a local station that is analog on 6 and digital on 13 (I don't think there is many that have both analog and digital on VHF), they are going to stay on 13. Makes you wonder why the FCC didn't latch on to channel 2-6 frequencies for resale also.......

[Geronimo]

It looks like a real mixed bag. Thanks for the link.

[HIPAR]

The lower VHF channels are more susceptible to interference from anomalous propagation modes. Normally, there are no problems but, during periods of high sunspots, there will often be interference from stations that are hundreds and even thousands of miles distant. Signals reflect from ionosphere at higher frequencies when the sunspots are most active during their 11 year cycles. There are also tropospheric ducting modes that sometimes occur when weather fronts are properly aligned or temperature inversions exist.

TV band interference is less probable as the channel frequency increases. It occurs much less often on the VHF high channels and almost never on UHF. But, it requires more power to cover a given area as the frequency increases. So Channels 7 -13 offer a compromise.

Digital TV (8VSB) modulation requires uncorrupted reception to deliver acceptable results.

That's my analysis.

--- CHAS

[KKlare]

Thanks HIPAR/CHAS for the info in your several messages.

I remember DX'ing from Miami (c 1959) especially on the low VHF (2-6) during hot summer days when the scattering was really good. One could get 500 miles on a tube set with those stations limited to 100 kW. It was hard to get the UHF converter box to bring in 1000 kW stations 10 miles away.

What are the other limitations? I notice no more than 2 DT stations in a row--something about third harmonic interference/cross-modulation. Yet they can place a DT next to an analog while you cannot have two analogs in a row and by 3's for cleaner UHF tuning. (Allow that there are breaks between 4 and 5, 6 and 7, and 13 and 14.)

What ever happened to one of the channels 37, 38, or 39 being reserved for radio astronomy?
-Ken

[HIPAR]

Appears that Chanel 37 is still going to be reserved for Radio Astronomy. Check out:

http://www.tvtechnology.com/features/On-RF/F_Lung-04.06.05.shtml

With reference to Figure 2, notice the gap at Channel 37. There are also geographical areas where channels in the 512 MHz band are not available because the spectrum was allocated for other purposes.

The power density in an 8VSB channel is very well behaved. There is no 'spill over' into adjacent channels and power is constant across the 6 MHz wide channel. I guess that's why they coexist well with NTSC signals.

--- CHAS

[newsposter]

what if a channel isn't listed (philly nbc10 -67-) ? That mean there is a chance they will pick another UHF? Or going to 10 again?

Also can I assume that 17UHF will be much stronger than 54UHF when it goes back to 17? It's a problem for me now.

[arxaw]

what if a channel isn't listed (philly nbc10 -67-) ? That mean there is a chance they will pick another UHF? Or going to 10 again?
If they're not listed, they will choose a channel in the "second round" channel election process.

Also can I assume that 17UHF will be much stronger than 54UHF when it goes back to 17? It's a problem for me now.
Yes.

[newsposter]

i found out 10 picked 34 and 34 is now bumping up to 35 per paperwork filed with the FCC . I've had perfect signals since my db8 was put on the roof and even started to get in pbs with about 90% recordable signal (minimal dropouts)

pbs will go back to 12 though, which i'm afraid the db8 may not be able to get like with 6 :(

[dsanbo]

Just as an FYI re: Reverting back to "old" channels" in '09.....
In my local area, there are 2 stations operating on VHF analog and UHF digital....BUT...those UHFs are channel 57 and 59 (!!). In 2009, they'll be HAPPY to return to VHF (channel 11 and 9) and get off those high UHFs...
IIRC....Channel 59 (used by WMUR-TV/DT) is the highest allocated UHF channel for ANY DIGITAL TV station in the US.....Anyone able to verify this...? Thanx in advance!

[boylehome]

Okay, here is what I don't understand and I hope you can help with your knowledge and expertise. It is and was a very big expense to convert to digital. Some stations have listed going back to their original channel. I thought that the digital equipment was specifically designed for the frequency that they are now broadcasting. If a TV station installed a UHF digital transmitter for UHF channel 34 then changes back to VHF channel 07 in 2009, what happens to the temporary channel digital transmitter for channel 34? Another question, once they go back to the VHF channel, where they have many distant analog repeater/transmitters with different channel assignments for outlying communities, how will they get the analog repeaters to work with the digital?

[arxaw]

...pbs will go back to 12 though, which i'm afraid the db8 may not be able to get like with 6 :(
Most uhf antennas can be used for upper VHF channels 7-13, although there are better UHF antenna choices than the DB8 for upper VHF.

Here's a comparison of some popular antennas:
http://www.hdtvprimer.com/ANTENNAS/comparing.html

[arxaw]

... Some stations have listed going back to their original channel. I thought that the digital equipment was specifically designed for the frequency that they are now broadcasting. If a TV station installed a UHF digital transmitter for UHF channel 34 then changes back to VHF channel 07 in 2009, what happens to the temporary channel digital transmitter for channel 34? Another question, once they go back to the VHF channel, where they have many distant analog repeater/transmitters with different channel assignments for outlying communities, how will they get the analog repeaters to work with the digital?
If a station is currently on digitally on a UHF channel and gets permission to use a VHF channel, they will have to replace their transmitter and antenna to match the new channel assignment. Many of the stations are only using cheaper low power transmitters and temporary antennas, which will probably be junked and written off, like analog equipment that will no longer be useable.

I'm not sure what will happen to translator/repeater stations, except they will have to stop analog broadcasting Feb 17, 2009, and all channels in the 52-69 range must vacate those channels.

[boylehome]

Many of the stations are only using cheaper low power transmitters and temporary antennas, which will probably be junked and written off, like analog equipment that will no longer be useable.


They may have some interested buyers in the background. From what I understand the FCC is now commencing the transition to digital for the low power stations. Most likely the low power stations can save $$$ if they buy the used equipment. Some stations in my DMA have purchased top grade transmitting equipment for the temporary channel and are going back to their pre-existing channel. I'm not seeing the logic, to which, I sure there is an abundance.

[arxaw]

There is a big incentive to go back to VHF, at least highband VHF (lowband VHF digital hasn't worked too well in many cases). They can get the same coverage of a UHF channel - or better, on VHF, using only a fraction of the power a UHF station requires. When you're using up to 1 megawatt ERP on a UHF channel, when 55kW ERP would get the same coverage on VHF, the electricity cost savings is tremendous. The cooling (A/C) costs are also significantly lower for a VHF because there's less heat given off from the lower power transmitter. Thousands of dollars a month savings in electricity costs.

Another reason to go back to a VHF would be name recognition of a channel number. Many stations have had the same channel number since the early 50s and would like to keep it.