what is the spacing between dtv channesl

[captex]

i read on the fcc site, that 2 channels close in numbers example 7 and 8 will have be to be 25 miles a part from each other ? and the channel that has the same number have to be (quessing) 100-150 miles a part are so? any body knows or have thoughts?

 

[TexasTom]

Not correct.

The FCC allows adjacent channels to co-locate (within 24 km of each other). Otherwise, adjacent channel spacing requires that DTV stations such as the channel 7/8 example that you gave be at least 110 km (approx 68 miles) apart. For cochannel, the minimum spacing is 223.7 to 273.6 km (139 to 170 miles), depending on whether the station is UHF or VHF, and which part of the country it is in.

 

[CW]

Not correct.

The FCC allows adjacent channels to co-locate (within 24 km of each other). Otherwise, adjacent channel spacing requires that DTV stations such as the channel 7/8 example that you gave be at least 110 km (approx 68 miles) apart. For cochannel, the minimum spacing is 223.7 to 273.6 km (139 to 170 miles), depending on whether the station is UHF or VHF, and which part of the country it is in.

If you are talking about DTV and not Analog/Digital in a N-1 or N+1 mix, there is a minimum spacing. For Analog and Digital mix (such as 7 analog and 8 digital) in the N+1 or N-1 setup, they can colocate on the same tower (Houston 8/9, DFW 8/9 and many other similar setups are in operation)

 

[dhett]

The FCC allows adjacent channels to co-locate (within 24 km of each other). Otherwise, adjacent channel spacing requires that DTV stations such as the channel 7/8 example that you gave be at least 110 km (approx 68 miles) apart. For cochannel, the minimum spacing is 223.7 to 273.6 km (139 to 170 miles), depending on whether the station is UHF or VHF, and which part of the country it is in.

If you are talking about DTV and not Analog/Digital in a N-1 or N+1 mix, there is a minimum spacing. For Analog and Digital mix (such as 7 analog and 8 digital) in the N+1 or N-1 setup, they can colocate on the same tower (Houston 8/9, DFW 8/9 and many other similar setups are in operation)

No, TexasTom is correct. DTV-DTV adjacent channels are also permissible if located within 20 km (12 mi) of each other in zone 1 (NE US) or 23 km (14 mi) in zones 2 (W US) & 3 (SE US) for VHF and 24 km (15 mi) of each other in all zones for UHF. The reason IIRC is that when the signals are of relatively equal strength, a station's signal will overpower the n+1/n-1 interference caused by the other station, but if they're located too far apart, where one's signal is very strong and the other's is relatively weaker due to distance, then the local station could cause interference to the more distant. After 110 km (68 mi), the interference shouldn't be an issue, although I wonder what happens when you're about midpoint between the two?

Buffalo NY has several adjacent DTV channels: WNLO-DT on 32, WGRZ-DT on 33 and WNYO-DT on 34, plus WKBW-DT on 38 and WIVB-DT on 39. Oddly enough, while WNLO and WNYO are co-located, WGRZ is 45 km (28 mi) away, yet the FCC still allowed it. (WKBW and WIVB are also co-located.)

Here in Phoenix, KSAZ-DT was initially to be on ch-23 and KTVK-DT on ch-24, while in Tucson, KUAT-DT was to be on ch-30, KVOA-DT on ch-31, and KOLD-DT on ch-32. The FCC switched the allocations for KSAZ-DT and KVOA-DT, so there are no adjacent-channel assignments anymore in Phoenix or Tucson.

Separation requirements: http://edocket.access.gpo.gov/cfr_2003/octqtr/47cfr73.623.htm

 

[captex]

thanks texas tom, cw and dhett, i always been fascinated in broadcasting in tv and radio and the general fcc rules. i don't know if i be in broadcasting or not and getting on this board helps out the confusing information.
thanks again