The AM Forum

As I understand it, most of the VHF TV stations went to UHF when they converted to digital, even though some of the upper band VHF ones stayed put, and a few of the lower band VHF ones moved to the upper VHF channels instead of UHF.  Supposedly, one of the reasons for the changeover was so that the gov't could squeeze additional revenue out of the economy by auctioning off the lower VHF channels to other services; therefore I would assume that most of the low band channels are now vacated.

But all the local channels still go by the same old channel number.  I was told that local CH 4 moved to CH10, but they are still listed in the newspaper TV guide as channel 4, and give their station ID as CH 4.  On cable, we still get all the stations on the same channels we always did.  The only thing different that I see is that with the converter box I can get the subcarrier channels using the rabbit ears or JS clip lead antenna.  I can't get any of these off the cable; they must be available only if you subscribe to one of the premium services, if at all.

So how is this supposed to work?  Is there still any kind of channel number layout?  Or is channel 4 in one city on a different frequency from channel 4 an another city?  If you move from one city to another, how are you supposed to figure out where all the TV channels are, if you still try receive over the air with an antenna?

..don...there is a group of guys, who are 1880,or so, around 3-5 am, eastern time...they are on ssb, but these guys appear to be "tv dxers"....i've listened, and they are reporting meteor-pings, bringing in tv stations, at that hour....alot of canadian stations have moved to the new tv digi-thing, but are still transmitting, in the lower portions...so, i'd like to know, if these guys are watching the new digi stuff, and propagation is helping the signals beyond the level, that they can see them, just as in the old days, with a "snowy" picture....

..sk..

What I read is that the reasons low VHF is avoided, is that Es and the high noise floor on low VHF are unfavorable for DTV (which is now lower power than the analog version on the same channel).

The channels that were sold are the upper UHF ones.

To me, the virtual channel assignments are a pain.  Don't know if they ever plan to get it straightened out.

I don't know if the subchannels are "must carry", but most if not all are available on our cable system in clear QAM.  No box needed on a clear QAM set but the channel numbering is messed up.  Also, most of the analog tier cable channels are repeated in clear QAM last time I checked.  Comcast is due to eliminate many analog channels here on Aug 11.  They want to give me 3 boxes, supposedly for free, so I don't lose channels on my analog sets.

Edit:  Just ordered 2 boxes.  Despite what they claimed, the 3rd box would have cost $1.99/month.  These are simple RF in to RF channel 3/4 out adaptors.  No HD or even composite connections.  Guess you get what you pay for. 

It will be interesting to see if they do the whole digital tier and On Demand.  They need to be activated per account, so in theory they could cover the extra-cost channels.

Oh.... and I found out they plan to keep the local "Basic Tier" analog channels indefinitely.  See...analog is not dead yet.   :P

Hi Don,

Yeah the whole tv thing is royally screwed up in my opinion.  Glad I don't watch a lot of tv.  I know a lot of people think the DTV is really cool but to me from an art and science of radio standpoint, DTV means they've come up with a protocol for coding and decoding and blast around 18 Mb into a 6 Kw class C FM rig on whatever channel they have been assigned.  In other words, a TV tx nowadays is basically a big high powered RF modem.  Not that different from a 440 MHz packet radio station.  Analog was a lot more interesting to me, except that having a few channels of varying resolution off one station is kind of nice.  

But, back to your question.  TV sets and converter boxes for off-air TV are supposed to automatically map displayed channel numbers to a station's actual channel assignment.  So to the viewer, the connection between the display channel and the real channel should be transparent.  I find all this annoying and I think life would have been simpler if every station had switched to their real channel identity.   Okay, so ch. 2 is now ch. 12.  We'd get used to it pretty quickly.  I assumed they continued to identify as ch. 2 while really being on 12 to make life easy for viewers.  Last month at the Hamboree I was making these comments to a group after the subject turned to TV and one of the guys who works for a Chicago station told me the reason for the old ---> new channel mapping had nothing to do with viewers but rather had to do with Arbitron diaries.  It turns out the Arbitron (or is it Neilsen) ratings boxes that they put on selected tv sets could not deal with all the channel changes so this scheme was developed so they could continue to be used as-is.  I don't really understand the technical details but basically it had to do with the ratings boxes and broadcasting lives and dies by ratings.

Sorry about ur wx. It has been okay up here but year before last, we had an August in which it rained every single day, the river in my town flooded, people had water in their basements, and two bridges here in town had to be closed to traffic because the water was so high.  Then two years before that, we had drought and I was afraid my one tree that holds up some antennas was going to die.  I got to have that tree!  Feast or famine.

73

Rob K5UJ  

Nothing has changed here, as far as I can see, since the transition. All my cable channels are still in the same place they were before the transition. On the one TV that I have a transition box connected to an outside antenna, all the channels I had before the transition are still the same channel numbers after the transition. The fact that they may be transmitting on some different frequency then before is really immaterial  to me. Why should I care, as long as channel 2 is still channel 2, channel 4 is still channel 4, etc. Of course, most of these channels now have sub channels which is neat and the picture quality on all the channels is great.

I care because I would like to manually tune the channels in my RV when I stop at a campground for the evening.  If I know there is a channel 14 ON channel 14, I should be able to select it manually and rotate the antenna for the best signal.  This scanning thing to find channels automatically is a crap shoot because I don't have a clue where to point the antenna when I'm in another state.  To scan the whole spectrum takes like 5 minutes and then you turn the antenna a bit and do it all over again and again.  Who can keep track of what direction had the most channels with a usable picture?  What a PITA.

(Even when the campground has a crappy cable system, instead of a little analog snow, I now get the clear QAM channels breaking up.  :( )

Don,

Here are some resources that may answer your questions:

http://www.tvfool.com/ (http://www.tvfool.com/)
http://www.hdtvmagazine.com/programming/broadcast.php (http://www.hdtvmagazine.com/programming/broadcast.php)
http://www.antennaweb.org/aw/welcome.aspx (http://www.antennaweb.org/aw/welcome.aspx)
http://www.global-cm.net/OFFAIRLOCALTELEVISION.html (http://www.global-cm.net/OFFAIRLOCALTELEVISION.html)

Terry

I always thought getting away on va-kaa was to forget about the BooB TooB.....at lest we used to..and hunting local video feed that's a waste of time....Turn ON The RADIO..... ;D...

73
Jack.

I guess this channel reassignment stuff seems a little misleading, at best.  The bottom line, however, is that most stations are on the same "channel" even though that channel may not be on the same frequency as it was.  The average TV watcher/consumer could care less.  They didn't know what frequency that "channel" was on before the conversion to digital.  Read my lips:  ITS ALL ABOUT MARKETING AND MAKING MONEY.  That certainly includes selling new TVs and associated hardware.

73,  Jack, W9GT

I feel for those who are strapped for cash and having to deal with the FCC to purchase freqs.

In this new digital age we do not have to think of channels. The tuner scans and looks for a valid signal and displays the "I.D." and other program info, that's it.


The lower VHF freqs are prone to skip and interference and now we don't have to worrry about it as much.
DXing digital TV............good luck

Fred

Our local channel 6 WRGB in the Albany NY area had audio just above the FM band and when they went digital it went away . They received many consumer complaints and estimated that they had 50,000 listeners for audio only. Well guess what, they are back on. The got a construction permit and are operating an FM transmitter "audio only" but not on the old frequency but above the FM band as we know it. Is that happening in your area? 

If it were standardised nationwide, there would be no problem.  But if channel 2 in Nashville is on a different frequency, or a different (VHF/UHF) band, from channel 2 in Chicago, that's where it becomes a PITA and confusing, particularly for the not-a-clue-technically public.

Let's say I have a really good antenna and I live on a mountain and I can get 2 channels on different frequencies from different cities but they both happen to be assigned virtual channel 6.  Wonder how my DTV would handle it?  ???  Probably couldn't.

Yeah, but it's not _above_ the FM broadcast band; it's _below_ it.  Ch.6 audio is on 87.7 MHz.  Instead of the narrow tv analog audio they're operating with an analog tv license but the 87.7 audio has a FM broadcast frequency response.  There's some sort of analog grace period that expires in a few years so the question is what will happen to all these channel 6 FM broadcast stations then the time is up.  The one in Chicago is broadcasting "smooth jazz" and to be a legitimate tv station they have some visual -- a looping slide show of Chicago scenery playing.   There's another one in Hawaii I'm told.  I don't know about the others.

I always get my "Above's and Be-low's screwed up"  But I can walk and chew gum at the same time.  ;D

From what I have read in some of the broadcast rags, this is pretty widespread throughout the country.  They transmit slide shows or focus a fixed camera on the DJ for the video part, just to keep it legal.

It should be no trouble to pick up on analogue receivers, but I wonder how many of the present day digital receivers hit a brick wall at 88.1 or whatever the lowest FM channel is?

There have been proposals afloat to reallocate TV channels 5 and 6 to expand the FM band and allow AM daytimers to change over to FM and relocte, or to allocate part of it as a subband that would be digital only.

I have seen some digital tuners (displays) go below 88.1, so it's a hit and miss thing for a broadcaster using a TV channel

Fred

The only PLL uprocessor controlled broadcast receiver I have is the one in my car.  on AM it goes from 540 KHz (or maybe it's 530) up to 1710.  FM goes from 87.7 to 108.1 I think. Maybe 107.9.  Not sure because I never listen up there.  But anyway, all of the PLL controlled channelized digital display receivers I've seen extend a bit beyond the band edges.  The bigger problem for the 87.7 stations if you ask me, is having people discover that there is something way down there to receive.  Most listeners probably don't bother tuning down below 89 because it's mostly college and high school stations down there, at least that's how it is around here.

UHF DTV has much better building penetration than VHF. It also does better with neighborhood QRN. I have L.E.D. traffic lamps 2000 feet away which used to put static on low V analog TV pix but not hi-V or U. FCC limits Po in VHF compared to UHF. That may change. 

Over 60 different DTV outlets viewed here with the ducting lately. TVDX isn't dead yet. It's more difficult in one aspect because I have to re-scan in different directions. It's easier in another aspect (pun intended) because the PSIP makes the call letters pop up instantly. Just google the call and bingo. A little faster than waiting for the station I.D. like in the NTSC days. 

Propagation is fun! Pity the appliance ops once again. Enjoy the bliss.

If you are into learning where the current politics are just google "white space devices."

Here, it's pretty crowded below 92 mHz all the way to the bottom end of the band, crammed mostly with religious fundamentalist broadcasters, plus three NPR stations and two independent university stations.  But no channel 6 TV here.

About all I ever listen to is the NPR and university stations.  The rest is garbage.  The university stations play some good jazz and blues from time to time.  The NPR stations play varieties of music including classical in between their news and talk programs.  The commercial stations have different music formats but they are pretty much all satellite repeaters with 8-minute long strings of commercials spaced 5-10 minutes apart, broken up with "playlists" of about 20 songs each.

Do those traffic lights wipe out HF reception at your QTH?

No. I hear them on ten with the monobander right on 'em but the noise blanker takes them out. 75 is already noisy because of plasma TVs. I have a pretty good 2 meter ant and I can hear the lights change easily on that on slopbucket or AM. Again the blanker takes it down. The R390A only gets used at night....

You're giving that clueless public more credit than they've earned. As a general rule, people are stupid. Most don't have anywhere near as much of a clue about how television works as your example suggests.

In fact, it only becomes confusing when you have some concept of a channel being attached to a specific frequency. Try telling people that television travels over radio waves, they'll look at you like you have two heads. They'll insist that you're wrong, because radio and television are two different things. To most people it's a box full of black magic; and the less they understand, the more comfortable they feel.

Having channel x be on a different frequency than it was doesn't confuse idiots any more than HBO being on different channels in different cities. The notion of channels was broken for most people a long time ago.

The mass-consuming public are to be presumed stupid until proven otherwise.


Handles it just fine. Again, the notion of channels being unique is long gone. Tuners no longer key their lookup tables solely on channel number. They now key internally by frequency, antenna input port, embedded callsign, and sub-stream selector. There's tons of identification meta-data embedded in the stream. The channel number is just a label it shows you.

You can launch any number of ATSC streams in your house and give them all the same primary channel number, and the TV will tune them all (and any substreams) just fine as long as the root streams are on different frequencies.

This functionality will allow for transparent translator service, as the next generation translators need not decode the main station and recode with a new channel ID. The tuner can easily tell them apart because it knows they're on different frequencies, but can also see that they're identical streams (all the identifying metadata are identical), so it need only show you the strongest one.

Bear in mind that televisions are no longer tuned to a single frequency at a time, they are constantly scanning the entire band. Only one tuner is dedicated to decoding programming for display, the others are used internally to maintain the lookup table and program guide.

If you guys think this is bad, try foxhunting a misbehaving RF node in a spread-spectrum grid topology. Good times. :P

...i cant verify this, but, i've herd that when the change over is complete here in canada, the FM  broadcast band is gonna be extended below 88mhz...likely to 76mhz...

..sk..

FWIW, I'm pretty sure it won't handle it in Windows Media Center.   If you try to add another channel 6.1, it will tell you it already exists.  That said, the Media Center app is a POS with all kinds of bugs M$ has failed to address for years.

Just as the FCC would find life easier if amateur radio would just go away, the FCC and the TV industry would find life easier if free over-the-air TV would just go away.

They were hoping the same thing down here, but it didn't happen. Too many TV stations petitioned for their old frequencies and got them back, because the spectrum auction held for the "vacated" VHF TV freqs was a flop.

A ton of new FM licenses were filed for under the assumption that the regulatory protections for channel 6 would go away and open the door for new FMs where they previously couldn't go without tons of compliance headaches. Those protections are still in place, so those applications are essentially dead in the water.

Given the whole 100 km border zone thingy, it probably won't be an all-encompassing change if it happens at all, much in the same sense that American hams can't use the bottom 10 MHz of the American 440 band within 100 km of the Canadian border to avoid interference to your allocations in that chunk of spectrum.

That's not to say it won't happen, just that we had our hopes up down here for a while before it became obvious that some of those "changes" just weren't in the cards.


Precisely. Screw windows media center. You're talking about a company that couldn't even devise a file system that didn't spell their name MICROS~1 until just over a decade ago, when all the real operating systems had tackled that decades before. If there's an app for windows that can handle an ATSC stream properly, it's very unlikely it will come out of Redmond. MICROS~1 themselves have been reduced to animated puppies and dancing paperclips. The real talent left and/or died 15 years ago.


Sorry, Don... but you honestly lost me there. What was that in response to?

Analog TV lives on in a lot of places due to must carry rules.

If they do make through all that just tell 'em that digital TV transmitters are really analog amplifiers.

I was hoping Canada wouldn't change. I noticed the TV stations in Montreal are still analog. Are they going digital?

..ya, they are, but not fer a year, or 2...i dont know what the lower channels are going to be used for in the states, but there would be alot qwarm from tv stations, if they did not move..

..sk..

That's just it, not all the VHF-Lo stations in the US moved. It's down to less than 20 stations from 2 to 6, but they're there to stay.

The transition did not go as originally planned, the auction had a low turnout, so many stations petitioned to keep their original VHF-Lo channels and won.

That was part of the point I was trying to make earlier, but I can't open my mouth without buzzarding.  :-\

Of course, if the Fee-Cee really wanted to expand the FM band, they could force those 20 or so low-band VHF stations to move, just as they did with the radiolocation beacons on 1600-1700 to make room for the expanded AM band. 

The radiolocation beacons were "reaccommodated" by giving them primary status in the 1900-2000 kHz portion of our 160m band.  Fortunately for us, the GPS satellites rendered the cumbersome and expensive 2-mHz radiolocation systems obsolete almost overnight.  Last time I listened, all the beacons had vacated the band, ever since the last holdout on 1952 kHz went dark.

Bingo.

Logical conclusion: they don't really want to, or don't care enough about it to force the issue.

..hey don...even with it being summer, noise etc., i herd a french station on 216kc, last night....about 11pm eastern...gud sig too...

..sk..

all the tv's i've seen just put 2 of the same channel in anyway. what is really a pita is trying to tell people around here that the reason they cant get wtaj-10 is because it is now on ch.32 and that just because it came in before on analog doesn't mean they can get digital because they have a vhf antenna and 32 is uhf and then they want to know what vhf and uhf is. btw the best dtv dx i've got is philadephia to here(about 150 miles, from there to fulton county, pa) on ch.6 from wpvi.
Shelby KB3OUK

Well I got my DTA (Digital Transport Adaptor) set up today.  Took about an hour before it got the activation signal from the mother-ship.  While I was waiting, I found a thread about this (Pace DC50X) box and learned about the diagnostic modes I coulld access.

http://www.dslreports.com/forum/r21518134-Digital-Transport-Adapter-Unboxing-Photos?r=0.382838776839105

Interesting thing I found out is due to FCC rules, this DTA cannot have de-encryption because it does not have the required cable card slot (to save money).  Therefore, all the newly unencrypted (clear) DTV channels (108 of them) will stay that way, and be viewable on any standard QAM capable DTV (but with no channel mapping). Silicondust (HDHomeRun company)  has been able to capture the in-band DTA channel mapping stream and convert it to a mapping table.  Hopefully, someone will figure out how to do it for Media Center PC's.

Comcast will turn off most of their analog on 8/11 here.

Update:  I decided to use the DTA as a front end for my Slingbox Pro since the internal analog cable tuner will soon be useless.  Now I can watch my DTA anywhere by internet or by cellphone PDA.  The tricky part was finding a driver for the IR remote control.  Sling still hasn't added the DC50X to their list of cable boxes.

BTW, it's bad enough that wall warts supposedly draw current from the line even when the device they power is off, but in the case of this DTA, there is no way to turn it off and so it runs all the time.  The POWER button on the remote is only designed to turn off the TV.  Not very "green".