And yet it hasn't affected their ratings.
-
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
Some clear thinking on IBOC: Skotdal: AM Band Needs Drastic Change
- Thread starter KB1OKL
- Start date
And yet it hasn't affected their ratings.
Yes.
I guess I should have clarified, I was thinking of skirt selectivity. I've heard radios that had decent (for modern AM) frequency response AND had good selectivity. With one radio, I can get 10 kHz audio on a particular station by setting the bandwidth to +/- 6 kHz and tuning 5 kHz off, and when tuning 20 kHz off there's no trace of it. Yet on another radio, the audio is fairly muddy on-channel (I'm guessing 3 or 4 kHz maybe, and tuning off to try to boost the treble doesn't work that well), yet the station could be heard like 100-200 kHz away. (Btw I'm thinking of 2 stations being heard at my grandma's house about 1/3 mile from their transmitter.)
What are the biggest obstacles preventing all modern radios from having good shapes on their filters, like the SiLabs chips have? (Although, my Tecsun radios do lack in avoiding front-end desense, though.)
Quote Originally Posted by mimo View Post
David, does that mean 40% of Americans tune into AM at some point during a week? Or do I have that wrong.
I find that very hard to believe! Do you mean to say that four out of every ten people, over the age of six, like News/Talk, Sports, Religion or foreign language programming enough to tune it in at least once a week?
David, does that mean 40% of Americans tune into AM at some point during a week? Or do I have that wrong.
I find that very hard to believe! Do you mean to say that four out of every ten people, over the age of six, like News/Talk, Sports, Religion or foreign language programming enough to tune it in at least once a week?
Last edited:
Consider that just under 20% of all radio listening is to AM, it is not surprising that 40% would listen at least once a week. In many markets, the news stations are AM only. In others, the sports station or stations are AM (this is a real factor if only AM has the local team's play by play). And large population segments that listen to religious broadcasts or ethnic shows are listening on AM. And then there is talk, which is one of the two or three most listened to formats across the markets in terms of cume.
This does not mean that they listen as much... probably because in any market there are fewer "listenable" AMs (based on signal alone) than FMs. But they do listen.
R
rbrucecarter5
Guest
I'm glad somebody is actually reading my posts! Very astute that you would catch what seems to be a contradiction, and that is my fault.
These posts time out. Unless I get in and out quickly - the site trashes them and I've done a bunch of typing for nothing.
I am sorry for the confusion. The spectrum analyzer indeed shows a nice rate of decay inside the building. Non HD and HD stations both show it. What I didn't say was that I had a radio on the same cart, and non-HD stations made it a lot farther. If I thought it would make a difference, I would take the time to publish a very polished, professional article with all the details on the research I have done. The problem is - IBOC is like a religion. Step on the sacred cow, you are going to get in trouble. Every FM owner, it seems, is brainwashed into thinking that this is the future of radio, if they don't run HD and their competitors do, then they will be left out. If they run HD-2, they can eventually sell commercials on it. I can't fight that brainwashing, I can prove HD is a technical disaster on several fronts, but publishing won't fight the HD religion. So why waste my time? I can make more money publishing engineering texts on other topics.
I personally like HD, because I get formats that stations won't run on analog. HD ever gets successful, those formats go away in favor of more popular ones. So whether it dies from consumer apathy, or succeeds in the marketplace, I am screwed. So I don't care. Everybody can ignore me about station range and building penetration. It won't make any difference if everybody ignores me or not. The problem will still be there, and other people have noticed it, too. The problem of consumer apathy won't go away, HD failed in the marketplace. Those cars that have it now - it will be GONE in a few years just like they dumped C-Quam because it costs a few cents more. The IF image problem that shuts off HD reception, that won't go away. In fact, I am noticing that 10.4 to 11 MHz undertones also seem to jam HD - sorry PBS stations, your low dial position doesn't make you immune to IF image blocking. AM HD jammed by power lines that run beside every road and street, that won't go away. Stations not giving a _____ about HD-2 whether it is on or off, that won't go away and discourages what few consumers like me actually listen. Our local two station duo proved that again the other day. In the last 3 months alone, HD was off for two weeks on one, then two weeks on another, now off on both. If HD was making money for them, they would have been all over the problem. HD doesn't make money for any station - and I doubt it ever will. It only appeals to crackpots like me who like the temporary niche formats. Only I am smart enough to know those formats will go away if it gets popular.
R
rbrucecarter5
Guest
I thought the Silabs chips were still pretty expensive. The AM version, as I recall, is set up so a single trace around the perimeter of the PC board acts as a loop. AM HD radios seem to have pretty good alternate channel selectivity on AM, although they cannot filter out first adjacents, because that would defeat AM HD. The biggest hurdle with AM HD in cars is that there are power lines running beside virtually every road and highway in the country. Even if there is nothing on the power line generating noise, the disruption of magnetic field alone seems to jam HD. We had a local 5 kW running HD on the upper part of the band, I had AM HD drop as little as 7 miles from their towers. They have since given up. There is a sports station 80 miles away running HD on 1620, when I get on a stretch of road without power lines, HD locks with no problem in spite of the weak signal. But if I get within a quarter of a mile of power lines, even quiet ones, HD drops immediately.
The biggest problem with HD AM in homes, is a myriad of switching supply wall warts, that are barely able to handle the load. I found an 0402 surface mount resistor burned out in one, a little detective work on the wattage rating shows it should have been a 1206 or larger case to handle the power. The result was RF interference on LW, AM, and Shortwave up to 25 MHz so strong it went several houses down the street. I am surprised nobody complained. Given that ATT cellular gave out micro cells free to all their users in my neighborhood - all with the same defective power supply - nobody in this neighborhood is going to get AM HD, EVER. The whole city of Houston doesn't have a single HD AM station any more. Now think about CFL bulbs, home networking, even new washing machines with large stepper motors, the old light dimmers, and dozens of other things that jam AM in homes, HD AM is not practical.
The biggest problem with AM HD in businesses is the steel beam and metal siding and metal roofs, the buildings are virtual Faraday cages.
So - tell me again why confusing the radio AGC with sidebands is actually going to help ratings? You can't change the physics of anything above. If a radio ramps down its sensitivity to accommodate the HD sidebands, it is not a good thing. If the ratings remained the same - that is fortunate for the station because it means a whole lot of people are kludging and tinkering to somehow get around the problems HD causes. I though there WERE no more AM DX'ers! Because that is what you would have me believe. I think it is much more likely that reception of AM is so bad these days that HD makes no difference at all, the signal was crummy before, everybody that can't listen to AM any more doesn't - HD or not. Or migration to FM HD-2 is actually making up the difference, but except for power lines, everything above affects FM too. So HD-2 listeners doesn't fly as an explanation.
The state of radio interference in the US is dire - radio station owners should be concentrating their effects in interference mitigation, and not into a failed technology that didn't deliver.
R
rbrucecarter5
Guest
Well, KellyA, who do you know on here who would have more experience as a DX'er? Wouldn't I be one of the first ones to notice if a station's range (and therefore its building penetration) is affected by something like HD? I am not asking anybody on here to take my word on faith. If you have access to a station - do the test yourself with a radio and not a spectrum analyzer. I am completely confident you will notice the exact same thing I do on AM and FM. I was listening during the conversion, know what station's ranges were pre and post conversion, and was lucky enough to find stations going back and forth on HD.
I will concede that maybe in one or two FM cases - the stations changed the type of bay they were using on their towers. BAD MOVE on their part! Their new bays stink. If that is what HD takes to work, its not worth it. But not every single station changed out bays. There are enough that didn't - and simply shutting off HD for a couple of weeks generated some reception reports on a Houston station way up in East Texas. I didn't report it, somebody else did. And that was with the new bays ---- the only variable was HD. I sure noticed it, no dropouts, no picket fencing, reception under bridges for that entire two weeks. HD back on, same crummy reception right back again. This was just a couple of months ago, it happens every time a station - any station - drops HD. The evidence is conclusive - before you flame me go do the test yourself, AM or FM - the difference is dramatic! Test it with radios, not spectrum analyzers. I promise - after you do - you will be right on here validating everything I have said! I am that confident of the science!
The proper test instrument is an FM Field Strength Meter with a standardized antenna. Not a radio, subject to variations in orientation and antenna pick-up methods (power cord, whip, etc) and definitely not a spectrum analyzer.
R390A's have excellent skirt selectivity thanks to the mechanical filters but they are not cheap. That muddy station probably has a filter on it to limit frequency response and it sounds like it is overloading your radio to be heard that far off frequency. Radio are only capable of receiving as high as the transmitter is broadcasting.
I don't think most people would want to bother to tune off center for good high frequency response, I know I won't, I can't stand the sound when it's off frequency.
I would guess cost is what keeps manufacturers from making good radios with good selectivity. That is of the many reasons I only use old tube boatanchors and consoles. Some of the mid thirties consoles with switchable selectivity really sound good. My daily radio is a 1937 RCA 816K, it makes AM radio sound great.
The president must seem like he's right in the room with you during those fireside chats, I bet.
Haha, you know it is odd to think that this radio in all probability did carry the fireside chats.
But your posts contradict themselves one to the next. You admit to using a spectrum analyzer to do field strength measurements, then you say don't. I suggest that rather than having spent so many minutes expounding on your media consumption preferences and life story, why not just post the test criteria you used to arrive at your conclusions? So far you've posted nothing but unsubstantiated claims, doublespeak, and a whole lot of nothing.
That last sentence pretty-much sums up the attitudes towards IBOC on this board.
I looked over some earlier threads from 5-6 years ago and find the same nay-sayer's names appearing. When it has interfered with their hobby of DX'ing they fume.
As someone with ties to the industry and who has used HD radios daily for almost eight years, I'll give my own two-cents.
What remains of AM IBOC stations here in NYC (WOR-WCBS-a and WINS) only WOR locks consistently. Since that station is a vanity clearance for right-wing gasbags -it is of no interest. However, WOR's collapse in ratings and demo's (near 40th place in desired demo breakout) it illustrates how even after being the first AM IBOC in the market (Nov '02) technology has failed to fix, or even help AM's dwindling audience.
In terms of sound quality AM IBOC is slightly better than an internet stream ca. 1999. It does eliminate background noise, but electrical storms and locally generated interference, the same things that plague analog AM, also ruin IBOC reception and cause reversion to analog. Under near-ideal conditions the system "works" but given real-world condition and the realities facing AM, in my opinion it is a dead issue.
FM IBOC is another matter. Clean floor, NO multipath, more open high end and no distortion due to excessive deviation (common here in NYC stations). The subs are a nice extra as long as there are not more than two. Overall it is a technical success but after nearly 11 years it hasn't moved the needle in market share. Hopefully the FM version will survive.
LCG
What you're probably hearing is the variance in characteristics of the ceramic filter(s) being used. Or in the case of the SiLab chip radios, which selectivity range is selected (on my PR-D5 it is a set range, probably 4 khz, which is great for DXing but the trade off is that it makes for relatively lo-fi listening on AM).
I think there are a lot of reasons different radios have different sound on AM -- much of it having to do with the audio chain, IF chip used, number of IF cans / ceramic filters, AGC characteristics, etc.
The IF circuits are a large part of it, but not the only part of what makes a radio sound good or mediocre on the AM band.
I applaud Andy for vigorously taking up the cause on behalf of AM, when most AM station and group owners remain silent. At least he has an opinion and is making suggestions. What I'm not sure of, is what the realistic impact of a single or multiple FM translators would have. Say you own a Class A station. As David has pointed out, even most 50KW stations don't cover the metro 24 hours a day, but its even more unlikely that an FM translator would provide enough coverage to make much of a dent, and there just isn't enough available channels to allow for multiple translators for a single AM station.
No, they are not voodoo.
In competitive markets, different stations serve different groups by age, taste, ethnicity and even gender. So different stations will be able to see how they do against the group they target.
In any given major market, as many as two thirds of the stations don't compete for ratings and sell based on service to religious, ethnic and other smaller subsets of the market. This is generally because they do not have the signal to compete with the major stations.
Last edited:
- Status