HD Radio

[judgemantx]

Can anyone share with me good or bad experiences with the HD radio in the Genesis 4.6? On my initial test drive, seemed like it was having issues finding channels and weak reception. Dallas, TX market.

 

[tarche]

I live outside of Philly and have good radio reception. I had no prior experience with HD radio so I'm not sure if it's normal or not, but my stations tend to come in and out. It will lock on to HD but then switch to stereo and then back to HD. Same for both AM and FM stations. I don't use the radio that much in the Genny (iPod and XM) and I just assumed it was normal behavior for HD radio.

 

[ctrcbob]

I find that the HD stations from Orlando will fade in and out from my location, 30 miles from Orlando.

BTW, took me a while to figure out how to get an HD Station.
1. When you are on an FM station, on the screen that gives you the frequency, if just under that freq number, it has a dash (-), there is no HD station for that freq. If there is the letters HD, that means that there is HD transmissions on that freq. If there is;

2. Push the DIS knob down so that the letters "HD" light up. Will say HD1. Then turn the DIS knob either direction and it will say HD2 and the next HD transmission will come on. If more than two, when you continue turning the knob, you will get a third (or more) HD transmissions. The stations in Orlando, that have HD have up to three HD transmissions.

BTW, "HD" does NOT stand for High Def. It is just a name, like XM.

It does NOT stand for something like FM (frequency modulation) or AM (amplitude modulation).

 

[mikec]

The HD part of a station's broadcast is another transmitter operating at 1% of the power level as the main analog transmitter. So it's quite normal for HD mode to pop in and out unless you are much closer to the antenna. The HD portion operates at frequencies offset from the main/original analog station - not at the exact same frequency. It's possible this offset crosses into the radio space of another station on your dial - if your market is really saturated with stations or another city/market is physically close. So the digital transmitter's power is limited, limiting the range of the digital signal so that it shouldn't interfere with the nearby markets.

That's the basic answer. Want the engineer's details? Read on... Want to be bored to death? Read on... Don't care about technical minutia? Stop reading now!

Radio station frequencies are set to specific intervals from each other because their frequency "footprint" is as wide as whatever bandwidth signal they broadcast. If a FM station broadcasts music with up to 15,000 hertz sound, the "footprint" varies +/- 15,000 from the frequency you see on your tuner display; this is sometimes called the "sidebands" of the signal. The original capability/design of FM analog allows +/-100kilohertz of sideband signal - even though nobody can hear music with such high frequencies. Instead that excess frequency range is used for the "subcarrier services" that some FM stations provide/sell. Stations within a given reception area are supposed to be spaced at 200kilohertz intervals (on your radio dial) so these bands don't overlap and interfere with each other.

This picture, from Wikipedia, shows a frequency "footprint" of an analog-only FM radio station operating at a tuner/dial frequency of 104.5 Mhz. This diagram is a chart of signal amplitude versus frequency; low frequency on the left increasing as you move to the right. The center of the display is 104.5Mhz, highlighted as MRKR2 ("Marker number 2"). Each black vertical line graticule/division on the display represents 50Khz. You can see the "hump" of amplitude is centered about this 104.5Mhz center point and extends about 2 divisions left and right from this center... 50Khz per division * 2 divisions = the +/-100Khz footprint of an analog FM radio station. The signal amplitudes around MRKR1 and MRKR3 are background noise... no other stations seem to be operating there in this particular city/market.

"Analog FM signal amplitude versus frequency footprint"

With the added digital modes, there is a 30kilohertz spacing band (unused sideband space on either side of the original analog signal+sidebands) and then +/-70 kilohertz sidebands for digital carriers added to the original +/-100Khz footprint. So the total footprint is 400 kilohertz wide with HD radio (70khz digital carrier on the low side, 30khz spacer, -100khz for analog mode low sideband, the basic "tuned frequency" center, +100khz for analog mode high sideband, 30khz upper spacer, 70Khz upper digital carrier). Think of the digital carriers as secondary FM transmitters broadcasting at frequencies offset a bit from the original/main FM analog transmitter since that's exactly what they are. One big analog signal at the "tuner" frequency, two 1% power digital signals at frequencies nearby. HD radios "know" how to find these nearby frequencies when tuned to the main/center analog channel.

This diagram shows a different FM radio station operating at 107.3Mhz on your FM dial. It has upper and lower digital subchannel information.

"Analog+Digital FM signal amplitude versus frequency footprint"

Again, the original analog FM signal is centered at MRKR2 on the dial. If you move 2 divisions left or right of MRKR2 you can see the analog signal amplitude drops to background just as with the analog only station described previously. Keep going a little more than half a division (going through the 30Khz spacer bands) and then you'll see the signal build up again: the digital sidebands. These extend to +/- 4 divisions away from the center signal: +/- 4 divisions * 50Khz/division = +/- 200Khz away from the center/dial frequency of this station. The +/- 200 Khz bandwidth limits are highlighted by MRKR1 and MRKR3 lines. Since the original design of FM radio allowed stations every 200Khz on your dial (which equals every 0.2Mhz or 0.2 megahertz on the dial) that means MRKR1 and MRKR3 could be other stations getting interfered with by this station's digital transmissions.

The 1% power limit comes from the digital signal using these "nearby" frequencies. Those "nearby" frequencies exceed the original +/-100Khz allocation of a radio station and thus overlap the next station on your radio dial. Most of the time that next station slot on your radio dial is empty; no city/market is so saturated with stations that they have to be right next to each other. Still, because a station MAY be next to another (especially when considering nearby markets) the digital power signal is reduced so that its range is limited and thus should not reach that nearby market to cause interference to that station's analog FM mode.

Digital AM radio is mixed to the analog signal differently than it is for FM; it's broadcast at the same frequency instead of at nearby frequencies. Analog AM radio uses much smaller frequency spacing between stations - that small spacing is why AM radio can't do high frequency music: the spacing limits the bandwidth/footprint. The footprints increase in AM digital mode though there is only one digital signal unlike FM. Still, this digital signal overlaps an adjacent AM station's allowable footprint leading to more interference. Since AM signals travel much further than FM (especially at night) there is a lot more interference potential on AM radio due to adjacent channel's digital footprint. You'll hear a waterfall hiss on your radio if a nearby digital signal is interfering.

Some broadcasters are petitioning for an increase in allowable digital mode transmitter power... to increase the range of the digital signals. Too many folks are experiencing what the original post of this thread described: digital mode popping in/out too often.

mike c.

 

[judgemantx]

Thanks for the heads up.

 

[HDproblems]

Of the 1,800+ HD Radio stations, only 150 have shown any interest in upping the power levels authorized by the FCC six months ago, so it basicaly is a bust. A number of AM-HD and FM-HD radio stations have turned off their signals because it is causing considerable interference, and there is no ROI for stations. Conversions of stations to HD Radio has stalled for some time. Reception will generally not get any better. There are already two Technical Service Bulletins from BMW and Volvo against HD Radio for not working as advertised. There are so many complaints that two law form (Keefe/Wolf) have opened up an investigation in automobile installed HD radios:

http://representingpeople.com/hdradio/index.html

 

[bpa5152]

I have some HD radio stations in St. Louis, however, I do not know how to activate then on my Genesis touch screen. The touch screen just says the station is in "Stereo". I know they are broadcasting in HD so what do I do to get this in HD instead of Stereo? Thanks

 

[mikec]

I have some HD radio stations in St. Louis, however, I do not know how to activate then on my Genesis touch screen. The touch screen just says the station is in "Stereo". I know they are broadcasting in HD so what do I do to get this in HD instead of Stereo? Thanks

For the 17 speaker Lexicon DIS package (Tech systems/non-touch screen NAV) systems that I'm familiar with:

FM stations:
If the station is also broadcasting in HD mode you don't have to do anything. Once tuned in, you'll see the "Stereo" tag in the upper right corner of the screen... after a few seconds, if the HD signal is present and strong enough, it'll change by itself to "HD Radio" and you'll hear the sound quality change too. Once that happens, you'll see the "HD 1" letters in the round blue frequency display too; press the DIS button down and the station frequency numbers un-highlight while the "HD 1" highlights. Now as you turn the DIS knob you'll step through the various HD feeds broadcast by that particular station. If the signal gets week (drive out of range, go through a tunnel, etc) the Lexicon system drops back to regular FM analog mode. If you were on the "main" HD channel, you'll hear the same song/program but with normal FM tonal qualities. If you were on HD2 or HD3 (the "extra" HD feeds) you'll hear nothing - there is no equivalent analog feed/signal to revert to so the Lexicon just goes silent. The upper right corner will say "No HD signal" at this time. If the HD signal comes back within a minute, the Lexicon will un-mute and go back to HD play mode. If the HD signal is unavailable for more than a minute, the system gives up on that feed and reverts to the main analog broadcast.

AM stations:
Again, once tuned in, after a few seconds of time the Lexicon automatically reverts to HD mode. Since AM stations can have only one HD feed, there are no options with the DIS knob... pushing it does nothing.

Note: in the "Settings" menu for both AM and FM there is a check box "HD Off" option, if the box has a check mark in it then HD is disabled. Use this if your station flops annoyingly between HD and analog modes while driving. There are "HD Off" options for both AM and FM - you can set them individually, like most of the Lexicon "Settings" options.

mike c.

 

[robthoke]

Where I live, there are no HD stations. I don't like regular radio, I don't want to pay XM any more, so I use DVDs, thumb drives or my IPOD. I'm retired and don't necessarily leave the house most days so it works for me.

 

[ImInPA]

For what it's worth, I have several HD Radio stations in my area. I find them superior in quality to SAT radio. I have a Volvo S80 and the HD Radio performance is superb. I find the HD AM stations to be as clear and almost as bright as standard FM. It is hard to believe the industry is not embracing this. I hope this technology does not go by the wayside.

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[bpa5152]

For the 17 speaker Lexicon DIS package (Tech systems/non-touch screen NAV) systems that I'm familiar with:

FM stations:
If the station is also broadcasting in HD mode you don't have to do anything. Once tuned in, you'll see the "Stereo" tag in the upper right corner of the screen... after a few seconds, if the HD signal is present and strong enough, it'll change by itself to "HD Radio" and you'll hear the sound quality change too. Once that happens, you'll see the "HD 1" letters in the round blue frequency display too; press the DIS button down and the station frequency numbers un-highlight while the "HD 1" highlights. Now as you turn the DIS knob you'll step through the various HD feeds broadcast by that particular station. If the signal gets week (drive out of range, go through a tunnel, etc) the Lexicon system drops back to regular FM analog mode. If you were on the "main" HD channel, you'll hear the same song/program but with normal FM tonal qualities. If you were on HD2 or HD3 (the "extra" HD feeds) you'll hear nothing - there is no equivalent analog feed/signal to revert to so the Lexicon just goes silent. The upper right corner will say "No HD signal" at this time. If the HD signal comes back within a minute, the Lexicon will un-mute and go back to HD play mode. If the HD signal is unavailable for more than a minute, the system gives up on that feed and reverts to the main analog broadcast.

AM stations:
Again, once tuned in, after a few seconds of time the Lexicon automatically reverts to HD mode. Since AM stations can have only one HD feed, there are no options with the DIS knob... pushing it does nothing.

Note: in the "Settings" menu for both AM and FM there is a check box "HD Off" option, if the box has a check mark in it then HD is disabled. Use this if your station flops annoyingly between HD and analog modes while driving. There are "HD Off" options for both AM and FM - you can set them individually, like most of the Lexicon "Settings" options.

mike c.

I have a 2011 Genesis sedan with a touch screen. I do not have any option to select HD in the settings.

Am I correct in assuming that this radio will access HD stations?

I am unsure what you are talking about when your refer to the Dis button?

 

[dg_moore]

I have a 2011 Genesis sedan with a touch screen. I do not have any option to select HD in the settings.

Am I correct in assuming that this radio will access HD stations?

I am unsure what you are talking about when your refer to the Dis button?

This is in the Tech Package

 

[ShoNuff]

For what it's worth, I have several HD Radio stations in my area. I find them superior in quality to SAT radio. I have a Volvo S80 and the HD Radio performance is superb. I find the HD AM stations to be as clear and almost as bright as standard FM. It is hard to believe the industry is not embracing this. I hope this technology does not go by the wayside.

Ditto. Atlanta has a number of HD signals, and they uniformly sound better than most of the XM stations. I too hope that HD radio doesn't go the way of the dinosaur.

 

[garddog32]

In Milwaukee there are a number of HD stations available.... some of them commercial free. There's a pretty good commercial free rock station I listen to frequently. There's also a comedy channel and many other pop/rock/country choices. The sound quality is much better than XM and FM. You can hear the difference when you tune to a FM station that has both a standard and a high def signal. The radio will first tune to the standard signal and then kick to the hd signal a second or two later. You can sure hear the difference. Where HD really makes a big difference is on AM. HD AM radio is vastly clearer than standard AM. However, the AM HD signal appears to be more flaky. I sometimes get dropouts from HD to standard with listening to AM. In FM mode, the HD signal is solid (at least in Milwaukee).

 

[JDC]

LA basin, no problem. Haven't check signals when going 'out of the area' yet.

 

[Onedurwho]

I'm still waiting for AM STEREO to kick in so I can get a return on my early-80's investment!!!

 

[ImInPA]

I'm still waiting for AM STEREO to kick in so I can get a return on my early-80's investment!!!

As an analog technology, AM Stereo radio was essentially doomed from the start. The noise supression and multipath characteristics of AM could never have delivered the experience that AM HD radio delivers. In addition, it required higher power (HD requires less power) to broadcast, so not many stations could justify the additional cost for, in most cases, no discernable increase in quality.