HD Radio going in and out

Welcome to the wonderful world of Digital Radio! First what type of antenna do you have, whip, sharkfin, coat hanger? Second thing to note now you are dealing in data, not analog audio on a simple RF Carrier with stereo pilot sub-carrier. If you get into an area of weak signal, or around tall buildings where you will get severe multipath distortion that will screw with a FM data signal even more severely that simple RF! Your reception all depends on your surroundings, your distance from the station transmitter, and their ERP!
As far as a fix, this is normal propagation of FM. there is not much you can do!

 

The way FM HD radio is setup in the US, it has a much shorter useable range than regular FM

 

why don't you try and tighten the antenna ( it unscrews )

 

The only way to improve this, is get a longer antenna, add a RF preamp, or drive closer to the transmitter. Path of least hope, get the FCC to allow the station to increase power!
All kind of impractical!
HD FM is great if you are at home, sit in the footprint of the transmitter antenna, and have a good receiver! Mobile, not so much!

 

Yea, this is normal since the HD Radio signal is only a fraction of the main analog signal. A power increase was approved for FM-HD, but few stations decided to up their power. Stations were not interested in buying new transmitters, installing new antennas, paying more for electrical bills, interfering with their own host analog signals, installing new air conditioning units, etc. The list of problems with HD Radio/IBOC goes on and on. Volvo and BMW have outstanding Technical Service Bulletins against HD Radio's many problems. Artist Experience will never work properly, either. I can't believe that the automakers bought into this scam. It appears they never really tested HD Radio properly. The law firms of Keefe Bartels and Wolf are soliciting HD Radio complaints:

representingpeople.com/hdradio/index.html

 

With the Prius v three (and probably other models) you can disable HD. I can't remember exactly how it's done, but try the radio's setup or options "button" on the nav screen.

 

Along the same lines - has anyone had any problem with needing to turn the volume down when switching from AM to FM because the two don't seem to be calibrated correctly? The initial answer from Toyota service was that it was the radio tower - but this isn't a problem in my other vehicles and it is consistent with all the AM stations versus the FM stations.

 

any stereo system that exhibits volume variation with mode (AM, FM, HD) is poorly designed/implemented. MY Pioneer HD radio (33HD) switches in and out of HD with no volume change, only a change in tone and noise. It was a replacement for the piece of junk (poor sensitivity, poor noise immunity and a CD player that never worked right) stereo that came with my 2004 Prius.

JeffD

 

You can disable HD on the main audio screen as it's playing. It's a touch button that says HD, although it defaults back to both on a restart.

 

I had a 2010 Prius Three and just traded it in for a 2012 Prius Four. I never had a problem with the FM stations in my 2010 Prius but now in the new 2012 Prius the FM station cuts out when going into my parking garage. I never have this problem when I drive my 2001 Nissan Pathefinder into the garage. What's up with this?

 

Less usable signal is getting into your radio. Either, crappy antenna, bad feedline, Bad radio. Not all radios perform the same. When the 2010s came out, there were many complaints about the radio. My wife's new HyCam has a great radio, and HD FM works wonderful.

First step would be to change the antenna, see if there is a difference.

While many of your points seem to point to lazy broadcasters, I would submit do you have any idea of what a capital investment to upgrade to HD FM is? Stuff don't come free!As for upping power, you buy by the kW, and it ain't cheap!
I sure will be holding my breath waiting for a bunch of Lawyers to try to figure out HD FM, much less win a judgement about it!

The radio in the wife's HyCam would seem to possibly be of better quality. Here in Los Angeles it works great!

Great example of "If you don't have a clue of which you speak, don't put foot in mouth"
ALL radio stations that pass their yearly Proof of Performance tests will have the same volume of audio. If the station decides to run their audio 10dB low, it's going to sound lower in volume. If your radio's AGC circuit (Automatic Gain Control), and ALL radios have this circuit, can not keep stations at the same level, the radio has a problem. Or it is just a crappy radio! Switching from AM to FM will produce a difference, but again it should be minimal.
Radio Tower, my nice person! What a stupid response to give you!

 

Changing the antenna won't affect the volume of an FM station as volume has no relationship to signal strength. (For AM stations, volume is directly related to signal strength, though the receiver's automatic gain control circuitry tries to level out the volume as signal strength changes.) However, a short antenna like that of the Prius v just simply can't pull in a weak HD signal as well as a full sized antenna. Since most station managers implement HD such that the HD signal(s) have shorter range than the standard FM, when the radio receiver can no longer receive a weak HD signal, it may automatically switch to standard FM channel. (One of the HD channels is usually the same programming as the standard channel, hence the possible shift when the HD signal becomes too weak.) An automatic shift between HD and standard FM might cause a volume shift if the car's receiver isn't designed properly so as to balance the audio between the two. Some (most?) receivers have internal adjustments that allow for balancing audio levels. If the Prius v radio has such an adjustment, it should have been set properly during radio manufacture and the dealer isn't likely to be able to re-adjust it (they hire mechanics, not electronic techs). So, if others here don't have your problem, then the course of action would be to have the dealer replace the radio. (I haven't personally noticed any changing volume issues because I've been primarily listening to satellite radio until my free subscription expiers.) In any event, HD radio hasn't impressed me. "HD" doesn't even stand for "high definition" and station managers can put HD signals on the air with quality either better than, or worse than, standard FM.

What you might do is park your car in a stationary location and listen to the radio. If you aren't moving, it's likely that the HD signal will not drop out and the volume won't change. If it does, try a few other stationary locations. If you have problems with all such locations, the radio is probably defective and needs to be replaced. When you are moving, it's not uncommon for weak signals (HD is usally affected first) to "drop out" from time to time.

 

I live in the fringe of Austin's HD FM stations and am in hilly terrain. FM HD does drop in and out and can't be permanently disabled as far as I can tell. My experience is the Prius' HD FM has a much better frequency response than the analog FM. It is a difference you can easily hear (like cassette to CD was) and I notice those frequencies dropping with the loss of HD. This loss kind of sounds like a volume shift because of the high end frequency response reduction. Meanwhile, the Prius speakers are quite faithful to the full frequency response of the HD tuner while the analog FM tuner apparently does not have any digital signal processing to boost the high or low end. I installed a longer antenna and gained some HD range (at 45 miles). When I am in the city, the HD holds well with the longer antenna.

 

HD FM radio may sometimes have higher quality than analog FM as you claim, but that's not true in all cases. If the station manager puts several HD data streams on the air, HD quality will suffer significantly as the available bandwidth for HD signals will be shared by each data stream. (The FCC does require that at least one HD channel at least match the analog signal in quality.) The radio in my Prius v sucks green weinies. I had to turn down the bass due to "booming," which is a clear sign of a system with poor audio quality. So, I'm surprised that you could hear any improvement in the audio quality of HD vs. analog as it's hard to believe that the Prius radio and speaker system would be able to provide high quality even if a high quality HD signal were received. Here's a link for a good discussion of HD radio: HD Radio - Wikipedia, the free encyclopedia By the way, HD radio is transmitted at only 1% of the power of the analog signal (with some experimentation at 4%), so HD signals are certainly going to have a shorter range than the analog signal.

Where did you get your long antenna? I'd be interested in installing one myself in order to improve weak signal reception, though it'd probably make it harder to find a parking garage due to height restrictions.

 

Could the volume mismatch be a problem at the particular station, not at the receiver?

The few stations I listen to seem to have well matched analog and HD midband volumes. I hear the transition as a change of bandwidth, more treble and bass in the HD than in the comparatively muffled analog. (Treble and bass adjustments are zeroed out, as deep bass boost causes an inner ear to spasm.)

I don't listen to any other HD radio, so have no basis to compare units.

 

My longer antenna (only a few inches extra) was from an 08 Prius. There are lots of compatible antennas although the aftermarket does not have the V in many of their compatibility tables yet.

 

I found how to disable the HD radio to force analog. Not in the Nav manual, but through trial and error. Looking at the FM Radio screen, when I touch the tab labeledHD Radio and the yellow vertical stripe in the HD Radio tab toggles on and off. When the yellow stripe is off in the HR Radio tab, the orange HD indicator above the frequency turns grey to indicate that you are listening to an analog signal. I hope this is not just a Adv. Tech. Pkg. function.

After you toggle the HD Radio on, it takes a few seconds to tune in and light up the orange HD indicator. I was playing with the HD Radio, and I could easily hear the better frequency response that rjparker talked about. I just sounded like surround sound was turned on and you could hear everything a little better.