Sunday, February 22, 2009

DTV and the poor preformance

I'm real disappointed that DTV conversion. Not that it was hard to hook up but the poor signal. In my area of Northern California the power of the DTV transmitters has gone up by 3 but the range has gone down by 3 to 4. Why a million watt transmission can't make it forty miles amazes me. I used to get with analog TV signal San Francisco which is 120 plus miles away at 300,000 Watts. Now with a million watts in my backyard that DTV signal doesn't reach me on a good night. I'd rather see a signal that maybe a bit ghosty but has the sound then a signal that drops out when it looses a few bits.

One thing that's wrong is the high compression ratio. MPEG compression only sees after the first key frame the changes in those frames. So when a minor bit drop happens the whole signal falls apart and takes time to recover getting the key frame which seems to be at least one second.

The audio was suppose to be better like CD quality that is if you can receive the signal. I've noticed that the audio signal comes out about 10 DB's down or 1/2 the signal then analog. I haven't looked into the bit rate of the audio yet to see if it's the same as DVD or CD quality. I do know that it skips like a DVD or CD and drops out like the pictures does.

Cell phones use a bunch of transmitters and receives to make it's system work. I think for DTV to work it's going to have to do the same thing, dozens of low powered transmitter towers spread all over to cover an area. The idea of one big transmitter just doesn't seem to work since weather, static in the air, rain, snow, wind, heat inversion layer all seem to affect the signal. Setting up a bunch of smaller transmitters with over lapping signals might be the way to go.

My video of what DTV looks like if you don't live under the transmitter.
DTV Quality Video