Is any California Stations going to Test out HD like
740 KCBS San Francisco
1070 KNX Los Angeles
740 KCBS San Francisco
1070 KNX Los Angeles
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AM HD Test
- Thread starter MarioMania
- Start date
KNX has been in HD for years, as has KFI.
Two Seattle AMs are doing all digital tests this weekend iirc.....they have discussed it on the Seattle board..(as if anyone really cares...there are not enough digital rcvrs in the consumers hands to justify a switch to all digital)
Two stations I think should test all-digital HD would be 1390 KLTX in Long Beach, CA (to see how much co-channel XEKT from Tecate steps on it), and 1040 KURS in San Diego, CA (to see how much adjacent 1030 XESDD from south of Rosarito steps on it).
What are some other examples of stations that have significant contour overlap? I think testing on some of those would be interesting as well, including some graveyard stations.
Another thing - I think at least someone (an experienced DXer preferably) who's testing on the receiving end should, before the signal switches to HD, go to a place where the signal is still detectable on an SDR's waterfall display in the daytime, but too weak to ID. This should be done in 3 situations: "in the clear", heading toward a co-channel, and heading toward an adjacent analog (non-HD) station. (On the way there, note the places where the signal starts to get noisy, then too noisy to understand speech, then SSB mode loses the carrier, for example.) Then, when the station switches to HD mode, retrace the path back to the station and note where the HD mode starts to lock.
Personally, I would think a good digital system would fully lock as soon as you can detect even the slightest trace on a waterfall display, even in the face of extreme co-channel or adjacent-channel interference.
What are some other examples of stations that have significant contour overlap? I think testing on some of those would be interesting as well, including some graveyard stations.
Another thing - I think at least someone (an experienced DXer preferably) who's testing on the receiving end should, before the signal switches to HD, go to a place where the signal is still detectable on an SDR's waterfall display in the daytime, but too weak to ID. This should be done in 3 situations: "in the clear", heading toward a co-channel, and heading toward an adjacent analog (non-HD) station. (On the way there, note the places where the signal starts to get noisy, then too noisy to understand speech, then SSB mode loses the carrier, for example.) Then, when the station switches to HD mode, retrace the path back to the station and note where the HD mode starts to lock.
Personally, I would think a good digital system would fully lock as soon as you can detect even the slightest trace on a waterfall display, even in the face of extreme co-channel or adjacent-channel interference.
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kenglish
Guest
The two stations in Washington are the last of this round of tests. I think there were about 7 stations doing tests of full-power, all-digital over the last few months.
I'm getting KKXA 1520 in crystal clear mono sound on their all-digital signal this Sunday afternoon. They've had transmitter problems yesterday and their IBOC signal won't lock on my Sony XDR-F1HD tuner. I'm at least 50 miles away in Auburn, WA. Kind of disappointing that their programming apparently isn't in actual stereo; I'm monitoring the audio on an oscilloscope that shows a flat diagonal line, not 'cotton candy'. KRKO 1380 was the same yesterday during their test.
I can't get KKXA at all when they go directional at night, a Portland station overrides the signal.
I can't get KKXA at all when they go directional at night, a Portland station overrides the signal.
Here are the results of the all digital AM tests for Andy Skotdal's stations in Washington.
According to Andy:
“Some said they heard the station with better clarity than with analog in the same location, some said they heard the station farther. Some said they had enough signal [that] they didn’t have to monkey with their AM antenna to get us and that the fading went away for them.”
http://www.radioworld.com/article/seattle-listeners-take-note-of-all-digital-am-tests/272796
According to Andy:
“Some said they heard the station with better clarity than with analog in the same location, some said they heard the station farther. Some said they had enough signal [that] they didn’t have to monkey with their AM antenna to get us and that the fading went away for them.”
http://www.radioworld.com/article/seattle-listeners-take-note-of-all-digital-am-tests/272796
I was talking to one of the deejays at KXA and he said that during the test they were able to pick up the KXA digital signal as far south as Olympia and that it came in clear and strong. Normally, the analog signal rarely comes in at all in Olympia. They were using the same power levels as their analog signal. So if the digital signal is this robust perhaps an AM station can cover its population with less power which could translate into quite a savings.
And typical of the HD purveyors' doublespeak is this gem:
"Of course, not all the feedback was positive. Skotdal says a few listeners made the point that they only had analog radios, weren’t about to buy a new digital one, and wondered whether all-digital was going to happen next year. “We helped alter their perspective of the future over the next 10 years and told them they’d still be able to receive the station,” he tells me, meaning explaining that current hybrid digital radios can receive the all-digital signal. "
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Out of the many AM HD stations I've listened to, I've found a few that I LOVE. If processed right, AM HD sounds amazing and I'd love to see it continue. Of course it sure makes the analog sound terrible.
Good with the bad I guess.
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rbrucecarter5
Guest
Out of the many AM HD stations I've listened to, I've found a few that I LOVE. If processed right, AM HD sounds amazing and I'd love to see it continue. Of course it sure makes the analog sound terrible.
I've heard AM HD on music stations. It curiously undersamples and shifts high frequency content down in frequency. The difference in sound quality (on the same station) when it was C-Quam and after it changed to HD AM was dramatic, and pretty much sold me on the idea that C-Quam was a superior stereo system.
When I used to use my Sony XDR-F1HD (how can anyone actually remember that model name?) on the very odd day when I could actually receive WBZ in glorious HD, I thought the sound was very artificial, especially the highs. It was not something I could listen to for more than a few minutes at a time, of course the other reason that I couldn't listen to it for more than a few minutes at a time was that it would drop out constantly. And yes AM HD really makes the analog signal sound like krap. WBZ used to be a good sounding station in analog, it sounds like it is going through a telephone line now.
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rbrucecarter5
Guest
Yes, and HD really gutted their nighttime range as well. They used to be a regular signal over Texas at night, not a trace of them now.
And why exactly should WBZ in Boston, care whether someone listens to them in Texas? Their advertisers don't buy advertising to reach Texas, or even outside of MA for that matter. Listeners in Boston could care less whether someone hears the station in Texas. Do you really think, with as many radio station as there are in the US, that catering to a handful of DX enthusiasts is worth even ten watts of RF?
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rbrucecarter5
Guest
You miss the point entirely. If they disappear over Texas, they won't penetrate buildings in Boston. Signal strength is signal strength - and it scales. HD is a power vampire, and saps a stations coverage and ability to penetrate buildings. The early testers of the system on AM and FM made one critical mistake - they used spectrum analyzers to test whether the signal stayed the same. Radios are not spectrum analyzers. They are confused by sidebands and ramp gain down accordingly. So the main signal may stay the same, but the radios can no longer get the station.
There are still some stations that care about sky wave at night, a good example is CFZM out of Toronto, another is WSM out of Nashville, these two stations are well known all across the country, neither has EVER had IBOC and both sound great and really get out there. Radio needs to get it's head out of the hole in the ground it is now in. A lot of people care about good radio like that, the problem is the dearth of good quality AM stations that broadcast music. AM radio bought a bill of goods 20 or 30 years ago that the only thing that sells is talk, that's baloney. If radio people are so smart why is AM radio supposedly going the way of the dinosaur? Which I don't believe. Channels are too congested and audio bandwidth is way too tight and there is way too much noise, part 15 ENFORCED would lessen that to a large degree and radio can definitely widen the bandwidth, if IBOC can pollute 30 khz of bandwidth why can't a good sounding 10khz wide station take up 20 khz?
That's not what happened. What happened is people simply stopped listening to stations that played current music on AM. The reason they stopped is they could hear a qualitative improvement on FM. Talk wasn't the only thing that sells, but it's the only thing people will listen to in large numbers.
Unless one is in the 100mVM coverage area, building penetration for AM is nil anyway. Have you heard of a Faraday Cage? Skywave certainly has no building penetration, so the argument about somehow listening outside the market is somehow an advantage, doesn't wash. Where I live in Stafford VA., I hear WBZ, WLW, and WCBS in analog and HD during the fall and winter after 5PM. But I'm a realist, if I couldn't hear those stations, I wouldn't lose any sleep or be upset either. DX'ers and old-timers longing for the good ol' days, (that I would also argue weren't that great anyway), is one of the many things that's holding any future for improvement or even survival of the AM band, back. And yes, I've been engineer for several AM stations since the 70's, so I'm VERY familiar with how AM stations worked, and work now.
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