Dallas, Texas TV Channel Spectrum

This is what Dallas looks like RF-wise as viewed on a spectrum analyzer using a Horizontally polarized Jerrold (now
Delhi) VU-933S Log Periodic television antenna pointing towards Cedar Hill - the highest point in Dallas County
and where most of the broadcasters in the VHF and UHF spectrum have chosen to locate their transmitter facilities.

It appears that we now have a total of *nine* new digital HDTV stations operating in Dallas. They may or may not be
carrying some sort of  programming material - perhaps they are just transmitting test-patterns!

Notes:

• Shown below are the active (currently transmitting some sort of RF signal) VHF and UHF TV "channels" as of 8-5-2002
• Vertical scale in all cases is 10dB/Division.
• Top line in all cases represents -30 dBm (30 decibels down relative to one milliwatt).
• Horizontal scale as noted on each Spectrum Analyzer photo.

All VHF Television channels, CH's 2 - 13.

Also visible is the FM broadcast band and just to the right of the centerline is a strong, nearby 2 Meter repeater.

Horizontal scale is 20 MHz per Division

                    |--CH's  2 .. 6--|FM Broadcast|--- Various 2-way, paging ----|-- CH's 7 .. 13---|-- Military --

CH 2 through CH 6 (a VERY weak video carrier is present) and the FM broadcast band (88 - 108 MHz).

Distinctly visible (from left to right) are the Video and Audio carrier-pairs (with the much weaker Color sub-carrier down about 30 dB down relative to the video carrier) for these channels:

• CH 2
• CH 4
• CH 5
• most of the FM Broadcast band

     -- CH 2 ---                      --- CH 4 ----          --- CH 5 ---             ------- FM Broadcast band -----
 

Ch 8 through CH 13 showing CH 8, CH 9 (a Digital signal), CH 11 and CH 13.
Distinctly visible are the Video, Color sub-carrier and Audio carriers for:

• CH 8 (WFAA)
• A Digital transmission in the slot reserved for CH 9
• CH 11
• CH 13  (KERA)

                           |-CH 8 --| CH 9 Dig |                     |- CH 11 -|                   |- CH 13 -|

UHF Television channel spectrum channels 14 through 41.

Horizontal scale is 20 MHz per Division

UHF Television channel spectrum channels 39 through 68.

Horizontal scale is 20 MHz per Division

Tabulation of Dallas/Ft. Worth area TV stations.

It appears the TV spectrum is filling out nicely in the Dallas Ft. Worth area.

This then begs a question in light of recent interest that may involve the FCC "cobbing" some television
spectrum and auctioning it off for another use - the question is: if television spectrum is going to be
auctioned off for additional 2-way radio, cellular or PCS services, where is this spectrum going to
come from?

Bear in mind when frequency planning cellular, radio and even television systems some consideration of the
"adjacent" frequency of nearby or area stations/transmiters facilities must be considered for a variety of
reasons including the need to balance signal strengths of the weaker, low-power TV stations against the
higher-power stations. And I haven't even addressed the question of the stronger TV transmitters in
proximity to these *new* 2-way services!  What about any required "frequency separation" for duplex
operation - are groups or bands of frequencies going to be assigned around different TV allocations?
"Frequency separation" for duplex right now amounts to 45 MHz for cellular and SMR or "trunked"
systems and 39 MHz for so-called "PCS" services at 1800 MHz.

Examples of tradeoffs in frequency planning  are already evident in the Dallas market. Examples include the
assignment of a weak CH 38 next to a strong CH 39 and a weak CH 57 adjacent CH 58 (where sync noise
is evident in each of the weaker station's video).

It's one thing having adjacent stations/signals in a cable system where signal strengths are all nearly the same
(and have been engineered to be that way) and quite another to active the same when stations are not
located geographically in the same location.
 
 

Note: Not all digital facilities transmit at all times. I have observed CH's 32 and 51 off the air during the
day (2002-08-07 13:10 CDT) and commencing broadcasting in the evening starting about 6 PM local.
 

AM Radio Stations (frequency in KHz).

Horizontal scale is roughly 10 KHz/Division.
 

              570        ---        590       600         ---         620         ---        640        ---       660
 

Instrument used: