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Post by CAwasinNJ on Jul 14, 2022 5:14:18 GMT -6
I now have an HD Radio (Sangean HDR-14). I know some of you have had HD Radios for quite a while so this is going to sound like old news. Sorry.
Something that was immediately obvious to me was how (at least on this receiver) some stations have the sync between the analog and digital signals correct and some don't. For those that don't it is REALLY annoying. Fortunately I'm getting a really solid digital signal, so there's little to no blending back and forth between the digital and analog signal. If I were in a moving vehicle and/or farther from the transmitter I'm sure it would make me give up on listening to stations that can't get it right. It makes no sense to me how this could be a problem. The parameters are known.
The other thing I noticed is that (again on this receiver) KSL AM HD sounds awful. I don't know if it has something to do with the limited bitrate of AM digital or if it's something with how KSL is doing the digital processing (I suspect the former), but the high frequencies of the audio sound distinctly artificial. It doesn't sound the same at all, but it is as distinctive as the swishiness of RealAudio back in the bad old early days of online sound files. Unfortunately I have no other AM HD reference since KSL is the only station I can find either locally or DXing that is in digital. Does anyone else hear this and is there any other AM digital station that I might try to play with location to try to pick up?
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Post by David on Jul 14, 2022 10:14:11 GMT -6
It's a long shot, but I did manage to pick up 1170 KTSB in Tulsa last fall when KSL-AM had their HD signal turned off during a BYU basketball game. I actually got the HD signal to lock for a minute or two with my Sangean HDR-14, before the signal started to fade and the Sangean lost its HD lock. Another HD AM station to try for is KMZT 1260. I've been able to get the HD indicator on my Sangean HDR-16 to flash with KMZT, but the signal wouldn't lock because there was too much interference from other stations on 1260. You might have better luck depending on your location. KNX 1070 was probably the easiest AM HD station to DX at night from Northern Utah, but their HD signal was shut off at least two years ago.
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Terry
Silver Level Member
Posts: 488
Usual Listening Area: east Murray
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Post by Terry on Jul 14, 2022 13:06:15 GMT -6
KSL-AM HD sounds fine on my HDR-16, but with earphones the high frequencies sound a little over-emphasized.
On my HDR-14 KSL’s high frequencies sound a little over-emphasized, but with earphones the high frequencies are annoyingly over emphasized.
On my old Sony XDR-F1HD tuner KSL’s high frequencies are obviously over emphasized but not too annoying.
(KJJC 1230, not an HD station, has horrible distortion on the high audio frequencies. I just can’t listen to them at all.)
I’ve read that the Sangean HDR-14 and HDR-16 use the identical decoder chip, so maybe the difference is in the speakers.
I haven’t heard any other AM HD’s since 820 shut off their HD. I can get my display to show “HD” on several distant stations at night, but never lock in on an actual digital signal.
Parenthetically, KKLV 107.5 is now in HD with 3 programs. And KBEE 98.7 is no longer in HD.
KKUT 93.7 HD2 (carrying KMGR) is my favorite music station, (very mellow oldies) but I can only get their signal (from above Nephi somewhere) when in certain locations in my house and with certain antenna orientations. I can’t find a stream.
I listen more to 105.1 HD2 because they have a solid signal.
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Post by christopherjohn on Jul 14, 2022 13:18:32 GMT -6
I applaud engineers who keep the analog/digital sync in check. There is no excuse not to keep things aligned. There are options to automatically do it for you. I have a Justin box on my station which constantly makes adjustment to delay and audio levels if things get a little whacky. It’s hard to hear the transition on mine.
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fmdj1
Bronze Level Member
Posts: 143
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Post by fmdj1 on Jul 14, 2022 17:02:39 GMT -6
I applaud engineers who keep the analog/digital sync in check. There is no excuse not to keep things aligned. There are options to automatically do it for you. I have a Justin box on my station which constantly makes adjustment to delay and audio levels if things get a little whacky. It’s hard to hear the transition on mine. As someone who wrestled with keeping an HD1 station synced with its analog counterpart off and on for a long time, I also applaud those who do a good job at it. For us, even using a GPS clock and a Belar monitor, we struggled. It only worked well when we kept the importer and exporter at the tower site, but that means driving up a mountain for things that couldn't be fixed remotely. Thankfully, Las Vegas doesn't get much snow, so at least the site was accessible year-round  |
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Post by christopherjohn on Jul 14, 2022 17:51:44 GMT -6
Yeah, that’s why I opted to keep everything at Farnsworth. All processing and timing. We are running the Gen 4 HD box by Nautel. Which is the importer/exporter in one box. Love how smooth they operate. I applaud engineers who keep the analog/digital sync in check. There is no excuse not to keep things aligned. There are options to automatically do it for you. I have a Justin box on my station which constantly makes adjustment to delay and audio levels if things get a little whacky. It’s hard to hear the transition on mine. As someone who wrestled with keeping an HD1 station synced with its analog counterpart off and on for a long time, I also applaud those who do a good job at it. For us, even using a GPS clock and a Belar monitor, we struggled. It only worked well when we kept the importer and exporter at the tower site, but that means driving up a mountain for things that couldn't be fixed remotely. Thankfully, Las Vegas doesn't get much snow, so at least the site was accessible year-round |
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fmdj1
Bronze Level Member
Posts: 143
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Post by fmdj1 on Jul 14, 2022 17:59:02 GMT -6
Yeah, that’s why I opted to keep everything at Farnsworth. All processing and timing. We are running the Gen 4 HD box by Nautel. Which is the importer/exporter in one box. Love how smooth they operate. As someone who wrestled with keeping an HD1 station synced with its analog counterpart off and on for a long time, I also applaud those who do a good job at it. For us, even using a GPS clock and a Belar monitor, we struggled. It only worked well when we kept the importer and exporter at the tower site, but that means driving up a mountain for things that couldn't be fixed remotely. Thankfully, Las Vegas doesn't get much snow, so at least the site was accessible year-round Nice! Plus they keep the trail groomed and there's always someone up there. Our stuff was a little older vintage (circa 2010) but also Nautel. I'm a big fan of their stuff. Truly the Cadillac of transmitter companies. |
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Post by christopherjohn on Jul 14, 2022 19:21:47 GMT -6
That they do. An awesome crew up there. We put our GV10 on the air in 2017. I agree 100%, Cadillac of the transmitters. There is now 5 of the GV series in service up there right now. Yeah, that’s why I opted to keep everything at Farnsworth. All processing and timing. We are running the Gen 4 HD box by Nautel. Which is the importer/exporter in one box. Love how smooth they operate. Nice! Plus they keep the trail groomed and there's always someone up there. Our stuff was a little older vintage (circa 2010) but also Nautel. I'm a big fan of their stuff. Truly the Cadillac of transmitter companies. |
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Post by CAwasinNJ on Jul 15, 2022 2:16:21 GMT -6
christopherjohn, I absolutely can't hear when KSOP-FM's HD kicks in, even when I'm watching the display. Great job.
Frank, you mentioned GPS clock. I remember reading an article many years ago about the company that designed the boosters system that the Humpy stations use, and as I recall they specifically mentioned using GPS. I don't recall ever hearing a sync problem between boosters. The concept seems simple enough, but I'm not an engineer.
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fmdj1
Bronze Level Member
Posts: 143
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Post by fmdj1 on Jul 15, 2022 18:18:09 GMT -6
christopherjohn, I absolutely can't hear when KSOP-FM's HD kicks in, even when I'm watching the display. Great job. Frank, you mentioned GPS clock. I remember reading an article many years ago about the company that designed the boosters system that the Humpy stations use, and as I recall they specifically mentioned using GPS. I don't recall ever hearing a sync problem between boosters. The concept seems simple enough, but I'm not an engineer. In theory, yes, a GPS clock synchronization should resolve any float problem. Our problem was maintaining the GPS lock. I'm not an RF engineer, so I'm not sure whether RF was the culprit, but I wouldn't be surprised since RF seems to get into everything. In my opinion, though, one of the biggest problems was the packet transport across our microwave system. Even though we were operating on a licensed frequency that theoretically should have been immune to interference, I could sit there and watch the speed and packet loss change while monitoring the dishes. The beauty of having the importer and exporter at the tower site is that network transport no longer mattered because the audio was sent up as a single digital signal and then the digital and analog were all handled at the transmitter. With the boosters you mentioned, I suspect they were able to maintain their GPS lock. If they were also delivering the signal via a traditional microwave method, they wouldn't have to worry about variable network speeds, otherwise, I suspect they had a decent buffer set at each of the sites to allow them to stay synced. There is something to be said for good old 950 MHz STLs. They just send the audio rock solid all the time. |
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