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IS HD the way to go for AM PHILLY STATIONS?

We had a BTA 50G (and 10G for night and backup) at WIBG 99 at 117 Ridge Pike.

Scroll down to page 28, http://fmamradios.com/Ampliphase_119.html , and look at the frequency responce curve of the 50H. (The main difference in this 1964 "H" model was the Solid State power supply.) The beast banged out 30 to near 18Kc in clean audio. +/- 1db. Simply amazing. It's downfall was that it wouldn't modulate 140+% like WFIL would. Sam knows the story. Archie Sichel did his best by making up the difference in loudness with AVC, average volume.

We used a Gates Vanguard II at WJJZ in Mt Holly as the BC-5 backup. It ran well, and the sound, when tuned, was really clean.

The "Old Fireball" was the RCA BTF-5 at WGRF in Atlantic City. We always kept an eye on it. And the front doors open for extra cooling. We were constantly scrubbing soot out of the tuning cavity.
 
Bad news: New digital test shows promise! Details:

http://www.insideradio.com/Article.asp?id=2644003&spid=32061#.UXcutkqPzYU

Just like everyone who's posted here, I'm in agreement with you all! Unfortunately, some corporate big-wigs are determined not to let HD-AM die! And this time, they want to go to digital-only! I still think this will accelerate the demise of AM as we know it! With all the brou-ha-ha, why is there little mention of a quality ANALOG transmission standard?
 
klutch...this was a failure for Ibuquity. Read between the lines. I posted the test results on Page 1/ Reply5 on this thread from a Radio World Engineering, not a reporter. Your link however, adds the mysterious missing information hidden from us in the RW article. Thanks.

Not surprisingly, the distances were significantly less for indoor reception: approximately 13 miles daytime and 7 miles nighttime from the transmitter site. 13 mile coverage for 10,000 watts!

Yes, "approximately 40 miles" daytime in the car with 10 kw, but only 13 miles indoors. So the hundreds of local coverage 1kw stations can expect their current coverage to shrink to 7 miles for at home/office listening, and MAYBE 15 miles daytime in the car, after they invest tens of thousands they don't have and kill off all their analog base to hash.

The home receivers need TRF circuits, and noise blankers...and a decent antenna.
 
Agreeing with amfmsw on home sets needing TRF stages and noise blanking.One of the best portables I ever had was the Radio Shack 12-655. That was a TRF, and I can remember hearing XEQ blowing CBM Montreal away on 940 one night.
 
My experience with AM IBOC (HD) had been limited to using a Sangean HD receiver that worked well on KYW at my Lansdale home. I was not able to receive a solid IBOC signal on any other AM station inside my Lansdale home. On KYW the signal to noise ratio was much better however there was a noticeable codec induced high frequency audio artifact that never existed on the previous wider bandwidth analog transmission. I still work in Lansdale at WNPV-AM and cannot receive any AM-IBOC at my office because of the strong RF from my own transmitter. In May of 2012 I moved to a new home in Franconia Township. My home reception conditions remain the same as at my Lansdale home. Last week, I purchased a KIA Sportage with my first Auto HD Radio. I can now receive 610 AM, and 1210 AM in the HD mode. The high frequency artifact is audible on those stations as well. The HD signal on my KIA radio is only 80% robust on 610 and 1210. The HD signal on KYW is 95% robust while I am in transit. I did some measurements in my area and determined that it takes an AM signal of 10 mV/M to give a solid mobile signal. I am so glad that my new KIA radio has the ability to turn the IBOC off. Except for testing, I keep it turned off.
 
I forgot to add my conclusion from my last post. Philadelphia HD radio on AM is nice to tinker with but the advantages do not outweigh the disadvantages and expenses.

Dave McCrork
 
It seems as though there are inherent problems with HD that are significant. With that said, if the analog signal was completely eliminated meaning that every AM station was moved over to HD but with more power to ensure that they minimally have the same coverage if not more, would this be the solution? Your thoughts are appreciated. :)
 
Most smaller AM Stations have enough difficulty with declining audience and revenue. A station would have to be insane to turn off their analog transmission in favor of a digital only mode of operation that would no longer be heard on any existing analog radios.

I really believe analog AM works well today, as we know it. We really should try to improve receiver design and have more radio people who have a passion for AM transmission.

Dave McCrork
 
Agreeing with Dave McCrork on this one. Far too many analog receivers still out there, and the digital hash wipes out a few frequencies either side of the main carrier. And there's the problem of IBOC on adjacent frequencies; take the case of KDKA and WBZ. And 'BZ's IBOC stomping all over Bob Savage's WYSL 1040 in the Buffalo market. I've heard WOR and WABC's hash make the 740 on Long Island nearly impossible to listen to.
 
What if the FCC did to radio what they did to television? By requiring all AM and FM broadcasters to go digital and informing the public that their radios will no longer work, the FCC could effect a solution by policy. For retailers this would be a positive kick in their earnings as millions of new radios would be sold in a very short time.

Is this a solution we should all get behind and rally for over the next year?
 
No, its not. There's too many analog radios out there and t they're stil being manufactured today.
There's good sounding receivers out there. if all manufactures put good sounding receivers on AM like they do for FM, maybe that would help something.
 
THAT policy, josh, would spell the end of this fragile business as we know it. Already in peril by lowrate-overloaded 8 in-a-row spot breaks. Dillusional processor maufacturers telling and selling us on how good 2.5-5Khz AM bandwidth sounds, while they Blast the FM band to the outer laws of physics.

This past weekend, I was stuck on the Schuylkill Xway westbound. KYW 1060, on a typical Sony narrowband AM radio with factory fender whip antenna was being crunched with interference, hash, static from the Vine St merger to Gladwyne, where we exited. The AM band in Philly is an IBOC toxic waste site of electical line noise, industrial noise, unshielded and leaking Verizon/Comcast computer and cable data, and Sideband IBOC hash that is louder than the main analog carrier. That includes imported toxins from 660, 770 and their brethern. And let's not forget the lovely hash spread from 590 to 630, 1040 to 1080 and 1190 to 1230. Cutting your analog audio to 5Khz does NOT stop the obvious, when the seek & scan stops at those channels everytime. Nor does it improve the digital audio one iota.

If AM is going to splatter 20 Khz, damn, let us broadcast 20 Khz Stereo audio in analog...what AM does best.

When I got to my destination in Limerick, we went to lunch in a my brother's Caddy with factroy HD. He had the 1210 Phillies on 98.1 hd2(?). It was so full of artifacts and grunge. And that was processing speech only. I fully understand evertime you split the HD signal it degrades, and WOGL is maxed out at 4, but enough is enough. It was a relief to my ears when he switched to XM.
 
Being a radio engineer all of my life has been a real pleasure. I have always tried to fine tune my stations for minimum distortion and reasonable audio quality. I am now 68 years old and have declining hearing on the high end. My high frequency response is -12db at 8000 hz! Even with that shortcoming, I can still hear awful artifacts on IBOC AM!

Also I have tried limiting the high frequencies on three of the stations I service to 5000 hz. The result has been a great loss of intelligibility on speech, and a lack of luster on music. I was amazed that even with my hearing shortcoming, I can hear a big difference between full response of 9800 hz and 5000 hz. What does a person with normal 15000 hz hearing perceive? The other station I service already has an 8000 Hz limit because of the digital STL frequency response. Most of the programming is talk anyway. The most profound test of audio response limiting was at WNAP-AM. We were a test station for another compatible IBOC system. I had to limit the audio response to 6000 hz and we did get comments and complaints from our listeners. Also the sideband hash was a real problem. Our 27.5, and our 297 degree nulls were all hash. Our station manager (Fred Blain) had me remove the exciter except when our partner company (Mobile Radio Broadcasting) was testing the digital system. During the daytime with 5 kW of analog power, the digital testing was only good to the 20 mV/m field. I do find that HD works better, but not much. Finally MRB got behind in their payments for service so I disconnected the exciter. That testing was done in 1998, and 1999.

I am very fortunate to have acquired a Kahn AM Stereo exciter model STR-84 that I have on a low power test transmission system. The audio quality is great and the separation is over 35 db. Leonard was a good friend of mine and I only wish that broadcasters had adopted his ISB system. Perhaps if that had occurred, we would not be messing with IBOC? Analog fits well on the medium wave band. If we had more spectrum space, IBOC would fit much better.

Dave McCrork
 
how about we tackel night time reception and storm reception first for AM? How about we tackel all the electric noise from powerlines? you said XM was a relief. that's pretty sad considering how bad XM sounds!
 
Nighttime reception on the medium wave band was and is What IT IS because of Sky Wave propagation. Manmade interference has increased dramatically over the past 30 years. Sky wave, co channel interference is also a problem because of the number of inappropriate foreign and domestic station additions. There would have been local relief if all affected stations were permitted a coinciding power increase. However, the result is not of good transmission efficiency. Even with our most efficient AM transmission systems, the power and operation cost are very high compared to analog FM transmission. Many smaller stations would like to limit their energy consumption.

A previous comment made reference to active noise blanking. There have been successful active analog and DSP noise and frequency response controls developed and used. The Tecsun Model PL-390 portable radio receiver has a DSP Rf and audio bandwidth control. In the most narrow band position, weaker stations are quite listenable. In the widest bandwidth position the audio fidelity is very good. As I do not have a schematic diagram of this receiver, I can not tell what type of noise blanking is used. I purchased three of these receivers and the work very well at home and in the field. Unfortunately, as with many broad pass-band tuned receivers there is great suitability to overloading in a strong RF environment (at a broadcast station). However, most radio listeners do not want to fool around with hardware to receive the entertainment or information they are choosing. This is a big plus for satellite radio.

This brings up another point regarding digital transmissions during an emergency situation. If a major emergency exists, very efficient and low cost analog AM-FM radios can be used to receive necessary information.
If an all digital platform is used the transmission and receive systems are much more complicated and very inefficient. Even if the cost of a digital radio were dramatically reduced, the system is still complicated by a decoder that requires 20 times more power than a traditional radio receiver. My wife and I experienced a power outage for 7 days during Hurricane Sandy. I was able to have reliable receiver performance with my Super Radio III. The battery life is 512 hours using D batteries. Had I been receiving an digital signal, we would have run out of power after a few hours. I guess I am suffering from OFD (Old Folks Disease) or
WhatIfItis ! I really believe that analog transmission and reception will always have a place in our emergency communications systems.


Dave McCrork
 
Reading this topic makes me wonder......does AM HD add noise the normal audio of the non HD signal?
If so what is that noise, does it sound like hiss? Is the conclusion that the HD signal lowers the same stations regular frequency response on their normal non HD signal? I have noticed when I turn the treble up on local AM stations on a regular AM radio instead of hearing more treble I hear more hiss. Maybe this is the reason.
 
not sure exactly what you are asking, but the frequency response of a analog stations is cut way down for stations that broadcast in HD, too. turnin up the trouble wont fix something that isn't there. if there's noise on the signal in the upper end, then turnin up the trouble would put more noise in your tuner, if the noise is in that frequency range.
 
Mandating all AM and FM stations to switch to all digital HD radio transmission would obsolete a Billion analog radios in North America and leave us without an effective radio broadcasting or radio emergency broadcast system. Almost no one would have radios able to receive the new AM and FM band digital only signals. No rush to buy HD radios because there are already so many better alternatives that many already own such as satellite radio, internet radio, WiFi, 3G, 4G, smart cell phones, cable etc.

A large universal power increase of all the newly mandated HD digital only stations would just create more hiss, hash and intermodulation interference between digital signals and huge increase in electrical and transmission expenses without much improvement in coverage.

On cable I get over 50 digital Music Choice music stations without commercials.

On the internet I get over 100,000 digital audio broadcasts from iTunes, Shoutcast, Icecast, and many, many other sources.
Plus satellite radio, podcasting, Slacker, Pandora, etc.

I get almost all the area radio stations noise free and digital from the internet, as well as stations from around the world.

Interference free AM and FM analog and HD radio reception doesn't exist in my high rise apartment building, and that is fairly common in apartments, office buildings and factories unless the transmitting tower is very nearby.

Remember the lessons learned from the analog to digital TV transition. Radio would be worse.
 
With respect to HD radio: The digital energy is transmitted on the sides of the main carrier and the analog (traditional) modulation. When receiving the HD AM station on a tuenable analog receiver, the tuning must be exactly on the center of the station frequency. The digital sidebands should cancel each other when the receiver is center tuned. If the receiver is tuned a little up or a little down the HD sideband carriers will be heard as HIS, Crickets and Squigles. Most new radios are center tuned by using a crystal locked tuning system. Most of the time these center tuned radios have very narrow bandwidths and the digital noise is not very loud. However this process compromises the analog audio on the HD stations, and creates adjacent channel interference. A good example of the crickets chirping is listening to 1040 Kc/s in Ambler and being able to hear the HD crickets from 1060 Kc/s.

There goes my OFD again!


Dave McCrork
 
The designers of AM HD had no interest in sound quality. It has a strange hollow sound for voice, somewhat as, but not quite as bothersome to listen to as a bad Sirius/XM channel. But strangely, music played loudly may just have a strange, compressed but good sound (at least in my car), but there are no AM stations in Philly for me to test. AM HD was designed by people who do not understand sound and should have been in a different business, messing up some other product. FM HD is another story though, in my opinion....some promise there, if anyone even knew it existed (since automakers never forced it on anyone like S/XM....)
 
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