Digital transition

Antennafreak

DTVUSA Jr. Member
#1
If I remember right,when the dtv switch occurred, vhf was to go 100% off the air. I thought I heard this was so they could improve communication during emergencies. Since when 911 happen they had so many communication problems. But really that is going to happen when you have so many people trying to use cell phones. Now it seems Vhf high band 7-13 is making a come back. Is this true. Also I've noticed the max power allocated to tv signals is waaaay less with digital now. I was hoping before the switch it would be so if you where getting the analog signal you will get the digital signal, but that seems to be far from true.
 
#2
I recall the same rumors, and UHF was being tested in the very hilly mountain valley where I live. Having some knowledge of signal propagation I was hoping that they would stay on VHF. I really thought that moving to UHF would have resulted in a great loss of coverage area, and would have required an increase in power. The major broadcasters here did move back to VHF. Two of them moved from low VHF to high VHF one of them stayed put on channel 10. Less power is needed to cover the same area using ATSC signals, more power is needed to cover the same area using UHF. The cut in power after the transition was excessive an increase in VHF power levels is needed. How well UHF low power translators work in my area came as a complete surprise to me. I can step out the door with a UHF loop and easily receive 300 watt translators from 30 miles away. Line of sight is required. I do not believe that would have been possible with NTSC signals. There are those who predict that with current spectrum grab money/politics there will be some return to low VHF broadcasting at higher power levels. I feel the major obstacles to low VHF are house hold RFI levels, and antenna size at those frequencies. I've always loved antennas, and have a bit of a problem with the current antenna phobia that has swept our country. I grew up at a time when a big TV antenna was a sign of prosperity. There are antenna manufactures that sprang up at about transition time that still have trouble facing the reality that VHF antennas are needed in the majority of US television markets.
Steve
 

Antennafreak

DTVUSA Jr. Member
#3
I think they are testing uhf in my area too. I get several channels that are no sound and just a test pattern. I also always loved antennas and am kinda sad at how hard it is to get one now. Unless online, not many stores carry anything worh while. It's amazing you can get a 300 watt uhf channel 30 miles away with a simple loop. Uhf may have a harder time cutting around objects, but sure does more weird things then vhf. Cool stuff.
 

Fringe Reception

Super Moderator, Chief Content Editor
Staff member
#4
... It's amazing you can get a 300 watt uhf channel 30 miles away with a simple loop. ...
Antennafreak,

I dependably receive a 40 watt RMS CBS translator from 17 miles on real channel 26. I contacted the Chief Engineer as he was astonished. Cool beans, huh?

Jim
 
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#5
To the best of my understanding most of the translators in my area are licensed to run 30 watts total power out, and 10db antenna gain.
0.03 kW TPO + 10 dB gain = 0.3 kW ERP Those numbers are from rabbitears.info for K28HL-D. On one of the rare occasions that I spoke to the owner of the translator he said often times he is only getting about 10 watts to the antenna. His comment about receive antennas was if you are line of sight a loop or bow tie is all you need. If you are not line of sight forget it.
Steve
 
#7
The rocky mountains make great antenna towers until something breaks down in the middle of winter, or even after a summer rain storm. While Height Above Average Terrain is one of the many determining factors in a transmitters coverage area. With the availability of Longley-Rice coverage maps I see little need to look up the HAAT of a given transmitter. In fact in hilly terrain it can become a worthless trivial number about like antenna mileage claims. While Longley-Rice coverage maps have known flaws they are the best tool we now have in predicting a signal coverage area.
Steve
 

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