AM HD lock. Strong sidebands, week analog

[kg4cyb]

Going to take a crack here. I wonder if you have mixing with another station on the center frequency but the digital sidebands are strong without interference, is it still possible to get a digital lock and digital stream? And It seems to me from my listening, the Upper side has to be free of interference in order to decode the call letters. I hope I am not confusing anyone. Example: WPHT 1210. Both 1200 and 1220 carry the digital signal. I cannot get a lock when 1220's reception is strong even though 1200 is always clear. But once 1220 fades, I get call letters and the HD signal comes in.

 

[RadeoEngineer]

It. Doesn't. Work.

 

[nd2023]

The goal of AM HD was to replicate the analog coverage flawlessly. It is a failure especially considering that the stars have to align to get an AM station in HD.

 

[tomservo]

A week of analog what? 8)

 

[w9wi]

Going to take a crack here. I wonder if you have mixing with another station on the center frequency but the digital sidebands are strong without interference, is it still possible to get a digital lock and digital stream? And It seems to me from my listening, the Upper side has to be free of interference in order to decode the call letters. I hope I am not confusing anyone. Example: WPHT 1210. Both 1200 and 1220 carry the digital signal. I cannot get a lock when 1220's reception is strong even though 1200 is always clear. But once 1220 fades, I get call letters and the HD signal comes in.

It works on FM. I've never heard of it working on AM, but can't think of a theoretical reason why it shouldn't. The situation where the center channel is suffering interference but a channel or two on one side or the other is clear is a LOT less likely on AM than it is on FM.

WPHT's digital signal is transmitted in 1215-1225 and 1195-1205. It's my understanding identical data is transmitted on both sides, so if either range is clear it should work. You'll need part of the 1230 channel open as well as 1220.

 

[nd2023]

In band, adjacent 2 channels.

 

[Savage]

Great consumer pitch for HD-AM, w9! "Get THEORETICAL great sound with HD on AM! In the real world - forget it! Every flip of a light switch, nearby compressor/electric motor starting or lightning crackle - digital's toast, followed by long silent 'reacquisition' periods....but hey, for two or three-second bursts, the sound is actually kinda neat!! As long as you like hollow artifacting...."

"Oh, did we mention skywave at night? You're totally screwed there! But at least you'll still have 4.5 kHz analog!"

"Break out the C-note for your AM-HD Radio, folks! Hasn't worked yet - but theoretically it could!"

 

[pianoplayer88key]

Instead of ramming IBOC up our _____s, wouldn't it be possible (and work much better if it's done right) to just use DSP or similar technology in analog receivers to dig the weak signals out from under the QRM+QRN and make them sound clear like we probably wish HD would be? Also, for C-Quam (AM Stereo) stations, is there some way to eliminate the platform motion caused by skywave fading and/or co-channel interference, while still allowing weak-signal stereo detection like my now-defunct-and-misplaced Sony SRF-42 could? From what I remember, that SRF-42 would decode stereo even with very weak signals (and even with stations without the pilot tone) - if a station was not being received in stereo mode, either you were mis-tuned (you had to be practically dead-on), the battery was dying (loss of stereo when you had it before was the first indication I had that the battery was weak), or there was no signal (as a signal got weaker, almost as soon as it lost stereo, I lost the signal completely). Re: weak signals, for example I could get stereo on 980 KFWB with that Sony, whereas another radio I had (and still have) that was a little bigger couldn't even hardly get the station at all.

 

[w9wi]

Great consumer pitch for HD-AM, w9! "Get THEORETICAL great sound with HD on AM! In the real world - forget it! Every flip of a light switch, nearby compressor/electric motor starting ...

By "It works on FM" I was referring specifically to the original poster's question -- whether it's possible to receive the HD signal of an AM station when the analog is not available. He wasn't asking whether HD was a good idea or a financial or technical success, so I didn't address that question.

For the record, I concur with those who feel IBOC was a bad idea; that it has little prospect for success in the marketplace; that it simply does not work on AM; and that it causes ruinous interference on the AM dial. (and could have easily been predicted to do so)

But that's not the question that was asked, so it's not the question that was answered.

 

[Savage]

I plead guilty to misinterpreting the purport of your post, w9. Excuse my face.

 

[Geographer]

By "It works on FM" I was referring specifically to the original poster's question -- whether it's possible to receive the HD signal of an AM station when the analog is not available. He wasn't asking whether HD was a good idea or a financial or technical success, so I didn't address that question.

From Kentucky, I heard WHAM from Rochester NY in AM HD with full quieting and great fidelity for about 30 seconds. This occurred when their analog signal was almost completely buried in co-channel clutter. Apparently, 1170 and/or 1190 Khz were momentarily clear enough to allow for a lock on one of WHAM's sidebands. If AM HD worked like this all the time, I would be an advocate of the system.

 

[Savage]

Hear them speak: "I listened (to) AM HD...with full quieting and great fidelity...for 30 SECONDS!!!" (Emphasis added)

If AM HD worked like this, you'd be an advocate? What about the adjacent-channel interference?
Suppose WWVA overcomes their antenna disaster and also starts running HD at night. You can forget about ever getting WHAM in HD again for 5 seconds, let alone 30. See??? THAT'S the problem.

"If ifs and buts were candy and nuts, we'd all have a heluva Christmas." :