Quote:
Originally Posted by Muscle Master
HD Radio is a sham, How the hell can you convert radio waves in to HD when can't convert radios waves, I'm puzzled and if it is true how does it sound compared to regular radio
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Before you call it a sham, I suggest you go understand the technology behind it.
HD, in this case, does not stand for High Definition, as in HDTV. It stands for "HD", as in it is just a marketing term. In reality, you could call it Hybrid Digital. The technology allows for radio stations to use something called In Band On Channel (IBOC) to simultaneously broadcast their standard analog radio signal, as well as a digital version of their analog signal, using the same frequency band. The digital conversion occurs at the source so the signal quality does not degrade while traveling through the air like analog radio signals do.
Depending on how much available room any given radio station has in its' assigned frequency band, they may be able to transmit 1-2 additional digital signals, in addition to their standard analog and digital versions. This sub-channel approach allows them to carry additional content beyond their regular programming, like having a classic rock station also transmitting an alternative rock substation and an 80's hits substation. Not to mention sending textual data such as traffic, stock info and song titles.
Do you really think that the quality of analog FM radio you get in your car is as clear as it was when it was sent to the FM transmitter from the station? Of course not, all the hissing, popping, and lack of dynamic range is caused as the radio waves travel through and around all the terrain between the tower and your car. With HD Radio, you get the digital version of the signal. Meaning, you get the same thing at your radio as was sent to the tower by the station. It's similar to streaming audio on the Internet...you'll get a encoded compressed digital stream that is then decoded by the receiving target.
Now, while their claims that FM will sound like CD quality audio are a bit exaggerated, it will have the clarity of CD (no hiss, popping, loss of dynamic range) but more like the quality of an MP3 encoded at 96kbps. They do use their own encoding paradigm that is based on perceptual quality (as the human ear would decifer the sound) and do not use a standard MP3, WMA, AAC, etc... encoding technology. Most people won't be able to tell the difference between a CD and an MP3 version at that compression level but audiophiles will be able to pick it apart and notice the slightly compressed dynamic range and slight loss in overall clarity. A typical FM signal would be similar to encoding an MP3 at 64kbps. At that level, a good portion of the population can tell there is a difference between the MP3 and the CD versions.
For me HD Radio is about the lack of analog signal loss during transmission combined with the ability to access the subchannels that stations can now broadcast. I'm well aware that Sirius/XM is a cleaner signal with more content but honestly, I'm not willing to pony up the $12.95/mo just to have to spend my hour long commute flipping through all 170+ stations trying to find a song I like.