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Old 01-01-2013, 8:35 PM
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Default SDR and HD radio

So I see alot of FM sations with definate signals on the side witch I presume are HD radio. I have tried everything and can't lock them. I guess the RTL sticks cannot do these signals. Am I correct or just slow?
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Old 01-02-2013, 1:15 PM
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FM signals are +/-200kHz from the nominal carrier frequency to include the subcarrier and the L-R stereo signals - this is what you are seeing. It's "frequency modulation", not amplitude, so the frequency goes up and down with the modulation, not the amplitude. AM stations are usually only +/- 5kHz.
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Old 01-02-2013, 2:57 PM
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I thought FM broadcast was +/- 75KHz deviation and 200KHz channel increments.
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Quote:
Originally Posted by majoco View Post
FM signals are +/-200kHz from the nominal carrier frequency to include the subcarrier and the L-R stereo signals - this is what you are seeing. It's "frequency modulation", not amplitude, so the frequency goes up and down with the modulation, not the amplitude. AM stations are usually only +/- 5kHz.
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Old 01-02-2013, 4:21 PM
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Quote:
Originally Posted by nmelfi View Post
So I see alot of FM sations with definate signals on the side witch I presume are HD radio. I have tried everything and can't lock them. I guess the RTL sticks cannot do these signals. Am I correct or just slow?
You are correct.

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Old 01-02-2013, 6:25 PM
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Yep that is what I am seeing.So even though the RTL sticks can see the signal they cannot work with them? Or is it a sofware issue?
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Old 01-05-2013, 10:30 PM
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I was led to believe the current problem with using SDR# or HDSDR (or a standalone application) to decode HD Radio is that the codec(?) is based on a standard format but altered in a proprietary manner, making the authoring of any plugins or add-ons a violation of license or intellectual property law. DAB and DRM are open source/open spec, so there are plugins and decoders all over the web, but Ibiquity is very protective of their format. Radio stations pay them gobs of money to license their HD broadcasts, and receiver manufacturers pay royalties.
Considering that the receivers really haven't come down in price very much, and most of the hardware implentations are either expensive car receivers or almost-as-expensive add-ons to existing car receivers, you would think they would either market them better or drop the costs of the equipment down to consumer levels, but when it costs USD50 for a Ipod-sized receiver you can take out on a bike, and all it does is HD, no MP3 playing, no AM, nothing, who except the blissful rich is going to buy one when you can take your existing smartphone and strap it to your arm and listen to your own personal songlist, or streaming broadcasts of loads of radio stations, satellite services, podcasts, scanner feeds, etc.
That said, there's probably someone laboring under intense flourescent lighting and Red Bull right now trying to reverse engineer the HD format and build a soft decoder. But it will be a tedious process--there'll be no one to bounce around the subject with on forums, no Sourceforge project, no public discussions or exchanges of information during the development process. The project would have be on the down-low, little or no support will be offered, the OS of choice for the initial development will probably not be a Windows OS, so you're going to be waiting for a port, if it happens at all. Sort of like DSD.
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Old 03-03-2013, 4:00 PM
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Default HD Sidebands

This reminds me of the audio on the old VCII satellite scrambling system, except rather than use an RF sideband, they inserted the digital audio data in both the horizontal and vertical blanking intervals. It was relatively easy to build a circuit to descramble the video, but extracting the audio took extremely complicated data slicers and FIFO circuitry timed with the video signal, then decoding the media layers to extract a DES-3 encrypted audio stream.

I'm sure someone can hack around with this and at least figure out the transport layers and perhaps extract some metadata pretty easily as long as there's no encryption involved. The actual audio codec is another matter.
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Old 03-06-2013, 4:52 PM
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These HD Radio sidebands play heck with analog FM stereo reception (using analog filters, of course) unless there is a post-detection filter. Using a narrower analog filter helps some but usually at a cost of fidelity.
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Old 03-12-2013, 1:44 PM
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Quote:
Originally Posted by nmelfi View Post
So I see alot of FM sations with definate signals on the side witch I presume are HD radio. I have tried everything and can't lock them. I guess the RTL sticks cannot do these signals. Am I correct or just slow?
What exactly are you trying to do? Just capture the raw signal? You should be able to do that.

Or are you talking about decoding it. That's currently not possible. As stated above, it's an issue of the codec being proprietary and little information being out there.

I think there is a good chance it will happen. Plenty of proprietary formats have been reverse-engineered. There is enough interest in it. That's not a assurance, however. In any case, no telling how long it will take for someone to do it, if it happens at all.
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Old 02-11-2017, 5:40 PM
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Can you still not listen to HD over a SDR? Stupid greedy media people.
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Old 02-11-2017, 7:10 PM
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Quote:
Originally Posted by beamin View Post
Can you still not listen to HD over a SDR? Stupid greedy media people.
Blame DTS, they're the ones who hold the patent to the codec.

Blame the FCC, they're the ones who only allow HD as a digital format on the AM and FM broadcast bands.


HD is the only option the "stupid greedy media people" have if they want to broadcast in digital.

No one is stopping you from writing your own software to decode the signal, it's not encrypted or anything.
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Old 02-11-2017, 7:17 PM
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Here is some work in progress on this no audio yet

https://github.com/philburr/hdradio
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Old 02-11-2017, 9:06 PM
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Whilel it as not as much fun as tuning it on a radio,

You can listen to HD radio at this web site.


https://hdradio.com/

Once there click on find stations
You will see in big type where it says Local radio stations

Under the line where it says all click on that to check for radio stations for your area.

That will give you a list of HD stations in your area.
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Old 06-15-2017, 9:03 PM
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RECEIVING NRSC-5 | THEORI
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