How Far Does the Digital Go?

[KB1OKL]

"Public radio wants to know how far its digital signals are going, and how susceptible to interference neighboring analog stations are. So the Corporation for Public Broadcasting commissioned NPR Labs to conduct a series of tests to find out... While an IBOC power increase would most benefit home listening, the resulting increased interference would likely hurt analog mobile coverage, Kean told Radio World... Increasing the IBOC power level from the current –20 dB to –10 dB causes a substantially larger amount of interference, including a larger number of stations that may lose 50 percent of their analog service population on a noise-limited service basis, according to Kean’s findings. He considers his approach different from how HD Digital Radio Alliance stations tested elevated power levels, on which we’ve reported."

http://www.rwonline.com/pages/s.0049/t.14274.html

 

[rbrucecarter5]

"Public radio wants to know how far its digital signals are going, and how susceptible to interference neighboring analog

Dipole reception is somewhere between 70 and 85 miles. I have personally done it 70 miles from the tower, another poster cannot at 84 miles from similar towers. Which tells me - why bother with a power increase? A station with a 70 mile radius of digital coverage should cover any metro area I know of with digital reception.

 

[SUPERCASTER]

"Public radio wants to know how far its digital signals are going, and how susceptible to interference neighboring analog

Dipole reception is somewhere between 70 and 85 miles. I have personally done it 70 miles from the tower, another poster cannot at 84 miles from similar towers. Which tells me - why bother with a power increase? A station with a 70 mile radius of digital coverage should cover any metro area I know of with digital reception.

Here in a major northeast metro you can't get most of the HD AM or FM signals (using the HD radio's supplied antennas) in radio stores within plain sight of the broadcasting towers!
HD radio dosn't seem to work well (if at all) in appartments, condos, row houses, brick houses, high rises, office buildings, or most anywhere else.
About the only thing HD radio seems good for is jamming adjacent channels, and it does that very well (at the present power level) over distances much more then 85 miles.

 

[Mike Walker]

With my roof-mounted antenna (with rotor), I routinely get HD to 100 miles. With an indoor dipole, the most powerful FMs from Charlotte (80 miles away) and Greensboro (60 miles) come through, but at least a third of them don't without lots of tweaking. Honestly, to the east of me (Greensboro direction...I'm in Wilkes County...in the northwest foothills) HD Radio on FM makes it through better than DTV. I get only one of the network DTV stations from the Greensboro market, though I get all of the digital signals from Charlotte. Incidentally, I can get EVERY Greensboro market analog tv signal and fm signal.

I'm more worried about the public-safety implications of turning off analog tv than I am about any degradation from HD on FM. Hurricane Hugo tore through this area not that long ago. Since we've had a blizzard, hailstorms, severe lightning, and several tornado touch-downs. I watched info of each of them on a battery-powered analog TV (when my power was off). That just wouldn't be possible (at this distance from the stations concerned with my area) with digital...and that's worrisome! Luckily both Wilkes County commercial radio stations have "live humans" on duty, and do a good job in bad weather. But most stations are unoccupied at least part of the time. These are the times that worry me. God help the folks in "tornado alley". I know people here love to gripe about how HD is the end of the world, but I'm FAR MORE CONCERNED about the public-safety implications of analog tv's demise!

 

[Play Freebird]

With my roof-mounted antenna (with rotor), I routinely get HD to 100 miles. With an indoor dipole, the most powerful FMs from Charlotte (80 miles away) and Greensboro (60 miles) come through, but at least a third of them don't without lots of tweaking. Honestly, to the east of me (Greensboro direction...I'm in Wilkes County...in the northwest foothills) HD Radio on FM makes it through better than DTV. I get only one of the network DTV stations from the Greensboro market, though I get all of the digital signals from Charlotte. Incidentally, I can get EVERY Greensboro market analog tv signal and fm signal.

So what do you use as the DTV antenna? It sounds as if your roof-mounted antenna makes a big difference on FM (no surprise there) but if the DTV stations are UHF and your antenna doesn't provide much gain in that band (or loss in the transmission line is high) I can understand why you're having some problems.

I use an attic-mounted Jerrold 4 ft grid dish with preamp to receive DTV and results have been excellent. Channel Master sells an 8-bay UHF bowtie/screen which reportedly also does a good job with high-band VHF:

http://www.hdtvprimer.com/ANTENNAS/cm4228.html

At least with digital television, it's feasible to install a high gain antenna (if you choose not to subscribe to cable) because most viewing is done at home.

On the other hand, radio is supposed to be a mobile/portable medium. This requires small antennas of unity gain (or much less) and receivers that can handle drastic differences in signal level caused by terrain, buildings, etc. A "single-frequency network" approach using multiple simulcast sites (similar to Eureka-147) would go a long way towards solving the HD coverage problem, but I guess this concept was too radical (and sensible) for American broadcasters to adopt.

 

[KB1OKL]

With my roof-mounted antenna (with rotor), I routinely get HD to 100 miles. With an indoor dipole, the most powerful FMs from Charlotte (80 miles away) and Greensboro (60 miles) come through, but at least a third of them don't without lots of tweaking. Honestly, to the east of me (Greensboro direction...I'm in Wilkes County...in the northwest foothills) HD Radio on FM makes it through better than DTV. I get only one of the network DTV stations from the Greensboro market, though I get all of the digital signals from Charlotte. Incidentally, I can get EVERY Greensboro market analog tv signal and fm signal.

I'm more worried about the public-safety implications of turning off analog tv than I am about any degradation from HD on FM. Hurricane Hugo tore through this area not that long ago. Since we've had a blizzard, hailstorms, severe lightning, and several tornado touch-downs. I watched info of each of them on a battery-powered analog TV (when my power was off). That just wouldn't be possible (at this distance from the stations concerned with my area) with digital...and that's worrisome! Luckily both Wilkes County commercial radio stations have "live humans" on duty, and do a good job in bad weather. But most stations are unoccupied at least part of the time. These are the times that worry me. God help the folks in "tornado alley". I know people here love to gripe about how HD is the end of the world, but I'm FAR MORE CONCERNED about the public-safety implications of analog tv's demise!

I don't like the government forcing anything down our throats, I'm not a conservative but let the markets decide.

 

[Kelly]

The forced migration to DTV began back in 1995 when Reed Hunt, (former FCC commissioner), went before Congress and told them that selling off the analog TV channels after the transition to digital modulation would put billions into the government coffers through auctions. Fast-forward thirteen years, if you looked at the vacated spectrum post-transition next year, there is mainly "low VHF" channels available nationwide. Due to the same reason DTV stations don't want low-V channels, that being impulse noise, I don't think the government will be very pleased with the lack of interest by data services, thus less money.

The good news is this turn-off of analog TV in 2009 will be a HUGE disaster in itself. I doubt radio will suffer the same mandate.

The current estimates is there are about 17 million people nationwide that watch analog TV Over The Air. Mike is right-on with his concern about the elimination of life-safety information to areas that rely on OTA TV broadcasting for news and information, especially weather. Radio provides an excellent service for sure, but you can't see those radar images on the radio.

 

[rbrucecarter5]

The forced migration to DTV began back in 1995 when Reed Hunt, (former FCC commissioner), went before Congress and told them that selling off the analog TV channels after the transition to digital modulation would put billions into the government coffers through auctions.

What a joke - the amount of money generated will be a tiny drop in the bucket for a government with bloated debt caused by tax and spend entitlement programs, and ill advised wars. Whether you have democans or republicrats in power will make no difference.

As far as the shut analog TV off - there won't be rioting in the streets, but there will be a lot of really PO'd people. I wouldn't want to be the party in power next year, because there will be a lot of new voters in the following election - people whose TV's no longer work.

 

[Chuck]

<snip> Mike is right-on with his concern about the elimination of life-safety information to areas that rely on OTA TV broadcasting for news and information, especially weather. Radio provides an excellent service for sure, but you can't see those radar images on the radio.

I agree. When the weather gets really bad around here, the first thing to go is my satellite. The next thing to go is my OTA digital TV. There is no cable in my area. All but one of my local DTV stations is broadcasting at their final power. If you are lucky, the TV will just pixilate and freeze up, but that usually isn't the case. Usually there is nothing, since digital is an "all or nothing" delivery method.

My HDTV has a signal strength meter on it. The scale is probably relatively meaningless, but under ordinary conditions it reads between 80% to 95% with an outdoor antenna connected. When it rains heavily, the signal may go as low as 50%. The meter works, but there is no picture. The threshold seems to be between 60% and 65%. Anything lower, and there is just a blank screen.

At least with analog, I can still see a snowy picture and hear the audio, even under the worst conditions. This could be a real concern, the next time a hurricane or tornado comes blowing in (and they do).

 

[jras20]

What kind of Dipoles are you guys using to recieve digital 70miles?? I have a hard enough time getting HD Radio with a dipole 30 miles from Austin!

 

[Chuck]

What kind of Dipoles are you guys using to recieve digital 70miles?? I have a hard enough time getting HD Radio with a dipole 30 miles from Austin!

I don't get much of anything off of the included dipole, although local FM's come in fine with it. Otherwise I'm using a Winegard FM antenna that claims 10 db of gain. It is about 8 feet long, and not something I think a casual listener is likely to use.

With reasonable reliability, I can get HD from stations 60-70 miles away with it. Trying to pick up Dallas HD (about 120 miles) is iffy at best and depends a lot on how the troposphere is acting today. I can frequently get a decent analog signal on those stations, but it is unusual if the HD will lock or stay locked. To be fair, that is extreme fringe, even for 100,000 watt stations on 15-1800 foot towers.

Since I have very little personal interest in DXing, these observations are made just to satisfy my own curiosity about this technology. You may have noticed that I’m not all that impressed, other than admiring the sensitivity and selectivity some of these radios offer.

 

[rbrucecarter5]

What kind of Dipoles are you guys using to recieve digital 70miles?? I have a hard enough time getting HD Radio with a dipole 30 miles from Austin!

Just the included plastic dipoles. I never was impressed with how robust Austin stations were. Somehow I don't think the antennas there are 1500 to 1800 feet -the signals fade pretty fast.

 

[rbrucecarter5]

signal on those stations, but it is unusual if the HD will lock or stay locked. To be fair, that is extreme fringe, even for 100,000 watt stations on 15-1800 foot towers.

I used to receive those same stations 330 miles away! Now THAT was extreme DX ---

 

[jras20]

The thing I like about HDTV, is having a radar sweep on HD-2. Thats basically the only reason why I upgraded to HDTV to see the radar. Other than that I could care less since I have directTV. Funny thing at my place outside of Austin, I have a pair of cheap old Rabbit ears and I can pick up Austin/San antonio DTV great with it. Hardly no drops. I am on a hill also, that might have something to do with it. But I always had great reception in this area. Out in Lavaca county is a diffrent story. But its really fun to DX out there.

 

[Mike Walker]

The dipole that gave me such great results (relatively speaking...it is indoors, in a very rural area after all) was the Magnum Dynalab SR100 "Silver Ribbon". I know there's no theoretical reason it should behave differently, or better than "rabbit ears". But it does...repeatedly and demonstrably. I have no idea why!

My roof antenna is a top-line Antennacraft, with rotor and mast-mounted preamp.

The things that scares me most about all-digital modes of radio and tv operation is that when weather conditions are bad, and you really need to know what's going on, digital can crap-out completely...whereas you would simply receive analog with a little interference (snow, hiss, crackles, etc.) The solution is to keep BOTH! Analog for distance reception and public safety (not to mention cheap receivers), digital for extra program services and (potentially, though not necessarily) better quality audio/video.

 

[jras20]

On the TV side, I believe they should keep everything on the UHF band. Out in Lavaca county Channel 11 (Fox) From Victoria, craps out when lightling is near. Channel 15 (ABC) does better. Both of those channels are pretty weak channels, but they do OK for the winegard TV antenna I have out at 20feet in the air. The thing I like about how Dipole works is all directional I can pickup both Victoria and Houston great with that thing out there. I also now use a dipole at my place near Austin. It can pick up Austin/San antonio good (Analog reception). My HDFM does ok with the dipole but it can only pick up Austin HD.

 

[Mike Walker]

jras20, if you already have a Winegard antenna at 20 feet, why don't you use for radio reception as well, rather than the indoor dipole? Just curious.

 

[jras20]

For some reason, it does not do good on FM. I have the old Radioshack's 15-2163 High gain FM Antenna outdoor antenna, but I have that pointed south to DX to Corpus and Victoria. (That one is also 20feet up) That one picks up a lot better than the winegard does.
I have the Winegard HD7080P it does great for TV. But I never understood why on FM it does not work very well.
The Dipole FM can pull in Houston great on analog, but HD all I could get was the call letters sometimes from the HD Signal.

 

[Chuck]

For some reason, it does not do good on FM. I have the old Radioshack's 15-2163 High gain FM Antenna outdoor antenna, but I have that pointed south to DX to Corpus and Victoria. (That one is also 20feet up) That one picks up a lot better than the winegard does.
I have the Winegard HD7080P it does great for TV. But I never understood why on FM it does not work very well.
The Dipole FM can pull in Houston great on analog, but HD all I could get was the call letters sometimes from the HD Signal.

Winegard antennas use a balun mounted on a PC board that is inserted into a plastic housing on the antenna. It can be replaced with a preamp. If I recall correctly, some models have a switchable FM trap on that PC board. Same goes for the preamps. If the trap is on, then it will be a very poor FM antenna. It might be worth checking.

 

[JohnnyElectron]

Q: How Far Does the Digital Go?
A: Not far enough. That's the biggest disapointment of HD radio - you don't reach as far as your analog signal currently does on AM or FM.