many Analog American TV stations will kill analog Feb 17 even if deadline is extended

[aerials]

Stations wanting to kill analog on the 17th. must inform the Feds no later than the 9th. of Feb.and I am sure the broadcasters will have to explain.

[karmaman]

FOX 5 in San Diego is doing the switchover on February 17. They run commercials every now and then stating that the gov pushed the date back but they are still doing it on the 17th, and to contact the station for more info.

[70salesguy]

Wilmington NC did an early transition to digital last October as a full-scale test market. I have been in Wilmington several times since then and things seem pretty normal.

There was an article in the local paper about some firemen helping people install their converters when they weren't fighting fires or washing fire trucks.

The worst part of this delay is 4 more months of those DTV-transition ads!

[kx250rider]

I just eMailed a friend at KTLA channel 5 in Los Angeles to ask if he knows their plans. They were the first commercial station to come online in 1947 here.

Charles

[Tower Boss]

All network affiliates here in the Spokane area have formally notified the FCC that they are proceeding with shutdown on the 17th as originally scheduled.

Regards,
TB

[andy]

000

[kx250rider]

Reply from my friend at KTLA: Plans undisclosed... But he's out on disability for a couple weeks, and says he may not be 100% up-to-date at the time he wrote the eMail to me.

Charles

[zenith2134]

From what I understand, it takes a hell of a lot of power to keep one transmitter running, let alone two! Bet the small operations are hurting from this somehow. I mean, sure digital broadcasting is more efficient but what good is that if both formats are running in unison?

We'll see how this pans out.

[electroking]

By the way, could someone enlighten me on these questions I have been pondering
for some time? Forgive me if it sound naive from an E. E., but will the biggest
ATSC transmitters be all solid state, or will they use tube outputs? Also, are any
power output stages derived from existing analog video transmitter designs, or
are they designed from scratch? Thanks in advance.

[andy]

000

[old_tv_nut]

There is very little major difference in the final power devices for ATSC and NTSC. However, there are details of the plumbing and sizing of the devices.
In NTSC, the max power is during sync, and some transmitters used pulsing of the outputs to reach peak sync level. This won't work for ATSC, which must be scaled to make the peaks at random times as required by the digital waveform. These peak values are mostly within +6 dB from the average power. Some peaks may go higher, but it is not crucial if they are compressed slightly, as long as the signal passes the EVM limits explained below.

Whereas analog transmitter performance was measured in frequency response and non-linear effects on the chroma carrier (differential phase and amplitude), digital transmitters are characterized by the "error vector magnitude," the deviation from ideal, measured as the ratio of signal-to-(noise+distortion) in the output, as determined by a standard test decoder.

Digital transmitters also have much stricter out-of-band radiation limits than analog transmitters, to allow the closer packing of stations within the available spectrum - so they have more complex baseband, IF, and high-level RF filtering. In fact, the FCC "mask" is so tight that most test instruments cannot measure the over-all result, which must be measured in two steps: 1) the raw transmitter output, and 2) the filter attenuation.

I believe tube finals are still in vogue for high-power UHF.

[old_tv_nut]

Originally Posted by andy

.

Does ATSC even require a different power output stage, or can they re-use their old one?

The old one generally will work fine, but the plumbing generally wouldn't meet the FCC mask. This is how many of the early tests were set up, when meeting the mask was not critical for interference during broadcasts from a single isolated transmitter. With the interim and final frequency allocations for 1600 stations, however, there were/are many cases of adjacent channel operation, especially digital next to analog during the transition years, so the mask was critical. The FCC was often clever in assigning an analog station their own adjacent channel for digital, thus making it in their own interest not to interfere with themselves.

Edit: I shoiuld note that the FCC mask specification didn't even exist during the early tests.

[zenith2134]

Hey, thanks for the info old_tv_nut! Great read.

Makes very good sense that the adjacent-radiation rules are stricter with digital...wonder how an ATSC receiver would react if presented with spillover OTA?

[wa2ise]

Originally Posted by zenith2134

..wonder how an ATSC receiver would react if presented with spillover OTA?

Just wait until the "white space" devices get loose. These are devices that would be used like wi-fi RF links for home computers and such. 100mW don't sound like much, but that's gonna be a big whopping signal that will jam a nearby ATSC receiver...
http://www.tvtechnology.com/article/68516

[zenith2134]

Hmm, how will the problem be alleviated? I doubt the FCC will be able to keep tabs on all of these devices....

I have a wi-fi here that operates at 2.4GHz and puts out about 100mW.....always wondered how safe it was to sit so close to it but thats another issue altogether.

Personally, I can't wait to see if any OTA digital 'pirate' stations pop up.....That would be neat.