Sorry - my number for the cutoff frequency may not be correct I was just repeating something from earlier in the thread. I know originally the cutoff was 5khz which was brutal and later they were able to widen it out some which helped a lot to my ears. I think I had read somewhere way back about it being 7 or 7.5khz. I do know when WBZ switched to this mode - whatever the exact cutoff was - the analog got way better, the background/digital hiss on my analog radios went away and on my HD tuner with signal health bars, it never went over 2 bars anymore even when in the strongest parts of their signal in Boston on the water front. So somehow that health was not signal strength but a measure of the HD resiliency.
-
Get involved.
We want your input!
Apply for Membership and join the conversations about everything related to broadcasting.
After we receive your registration, a moderator will review it. After your registration is approved, you will be permitted to post.
If you use a disposable or false email address, your registration will be rejected.
After your membership is approved, please take a minute to tell us a little bit about yourself.
https://www.radiodiscussions.com/forums/introduce-yourself.1088/
Thanks in advance and have fun!
RadioDiscussions Administrators
HD on WINS and WCBS AM
- Thread starter mets18
- Start date
Sorry - my number for the cutoff frequency may not be correct I was just repeating something from earlier in the thread. I know originally the cutoff was 5khz which was brutal and later they were able to widen it out some which helped a lot to my ears. I think I had read somewhere way back about it being 7 or 7.5khz. I do know when WBZ switched to this mode - whatever the exact cutoff was - the analog got way better, the background/digital hiss on my analog radios went away and on my HD tuner with signal health bars, it never went over 2 bars anymore even when in the strongest parts of their signal in Boston on the water front. So somehow that health was not signal strength but a measure of the HD resiliency.
Good catch. WINS is still using it.
Depending on the audio chain. If you have the "pre HD" settings and equipment or "corporate settings" less than an hour. It might take an hour or two if you have to do it the old way with running tones at different frequencies. Sort of like the old proof of performance back in the day which was usually done after midnight. The new PC based audio processing equipment should make this easy.
IMHO WSM 650 Nashville sounds really good in analog. The rumor is they run a "FM" type audio chain up to the transmitter where the 10 KHZ (stone wall) filter does its thing.
Go into the Output tab of their 9300 Optimod. Change the HPF to 10Khz. Done.
"Sounds really good" and "AM analog" don't jibe. Even the best AM tuners start rolling off higher frequencies at 3 kHz. By 7.5kHz, most are down by 20db.
It's all relative. Some AM stations sound much better than others even on lousy receivers. 1010 WINS "sounds really good" on a typical AM radio. I don't hear other AM stations sound like WINS and I've always wondered why not. The EQ settings they use seem to punch through the terrible sound quality of modern AM tuners, making speech sound rich and clear, and allowing S's to actually be heard. They would probably sound even better if they'd lose the IBOC and open up the analog high end.
Old radios seem to last forever and a lot of the vintage models with better AM frequency response than that are probably still in use. On some of those older radios you can hear the IBOC hash as hiss, and it's very annoying. On the other hand, extended high frequencies on analog AM signals really can make a difference on radios like that. I have a Philips AM/FM clock radio bought from Target as recently as the 2000s that still has decent sound quality on AM, so they are out there and not all of them are from back in the 60s and 70s.
They're supposed to start rolling off by 3 kHz, to match the NRSC pre-emphasis curve. Otherwise if the tuner's audio response was completely flat on AM, it would sound unpleasantly shrill.
And you make my point: Anyone who claims that audio sounds pretty good when it starts rolling off at 3kHz, needs to have their hearing tested. And yes, I'm familiar with the 150 microsecond preemphasis curve for AM. The LPF is required, but the NRSC preemphasis is not. Most modern radios roll off high frequencies that make preemphasis unnecessary.
Not surprising if you are moving in a car. There are sooo many sources of interference to prevent the radio from even sensing the HD signal.
But, it would be interesting to see if all of that interference would make a difference to a station NOT broadcasting an analogue signal to confuse the radio.
Jeff in Sa-ra-so-ta!
Are there any remaining AM HD Stations that are receivable on Long Island? My car radio also sweeps the entire band and cannot find a single AM HD. It shows there is HD on 1210 from Philadelphia but the signal is too low to trigger. I used to see the same thing on 1080 from Hartford … also too weak.
I'd be pretty confident that it is less than 100. If I get to pick a number, I'd say 60.
As of July 2019 the number was 114:
http://topazdesigns.com/iboc/station-list.html
I've sent some updates to that site's creator, but he seems to have abandoned it.
- Status