Tuesday, March 3, 2009

Digital VHF-HI: Not Everything as Seem

For years, digital over the air viewers waited with baited breath for that magical day: February 17th, 2009. A day when analog would die and digital stations would move to their final destinations. Well.. that kind of happened. Because the transition deadline got pushed back to June 12th, 2009, only a fraction of stations went all digital.

One of the touted benefits of the transition was that some digital stations were going to move back to their digital channels to VHF-Hi (ch. 7-13) allotments, meaning less output power and better coverage.

After a few weeks, it has become fairly clear that the proposition of VHF-Hi digital TV was an "Epic Fail."

Around here, WKBT 8 (CBS) La Crosse, KTTC 10 (NBC) Rochester and WEAU (NBC) Eau Clare all switched to their VHF-Hi channels.

WEAU 13 switched on Monday the 16th. Most Rochester viewers are at least 85 miles from the station. In spite of the distance, many were able to get a perfect color picture during their full power operation and a pretty good color picture during their months of reduced power output. Currently, I have yet to find one area viewer that can actually pick up their digital channel reliably, despite the fact that many of us were able to get their UHF digital channel quite reliably. The station is operating around 20KW and seems to be at that power.

WKBT 8 switched at around 1pm on Tuesday the 17th. Many people reported loss of signal strength when they moved over to ch. 8. Some even lost reception compared to the DT-41 signal.

KTTC 10 switched on the afternoon of the 17th. While my signal is about the same, I hooked up rabbit ears to a TV (where I could get a pretty good picture on analog KTTC) and was unable to get a stable lock on the station. Many people have also reported issues with the station.

What's the issue, you ask? Well consider this. Full power analog UHF stations get 5MW, while their digital channels run at 1MW and they seem to cover about the same area. Yet, VHF-Hi analog channels all operated at 316KW and now most digital VHF-Hi stations are operating in the 20KW to 35KW range. That's only 1/10th the power. Because VHF-Hi stations are also combating a higher noise floor than UHF, it seems the only probable solution is to raise the output to ~75KW. Hopefully, this will happen sooner rather than later, but we'll see.

If you've been effected negatively by the transition, now you know what's going on and um... your not alone.



Ron_Amundson said...

Thanks for the explantion, I too lost WEAU, and also KTTC. I sort of wonder about the power increase, as to how much it will help. I'm thinking it will clear up a signal with drop outs pretty well. Otoh, for those of us where its not coming in now, I'm no so sure. A 3X increase in power may not be enough. Of course it depends on the noise level... but also, we dont have vegatation at the moment. I think its going to be pretty messy this summer.

jimbo said...

I have lost my local stations WNYT, WXXA and WNYA since they switched to VHF-HI digital tv. The others are on digital VHF-LOW and UHF, which come in fine.