Five channels?

[markjfine]

Unsure if this is a mistake, but WWWT in North-Central Virginia is now showing a total of 5 HD channels:

HD4 isn't generating any audio in nrsc5, so who knows what's really going on. Of course, trying to access HD5 in nrsc5 is a non-starter.

[markjfine]

Lol... Just checked WWWT and now HD2 is 25kbps of dead air.

[markjfine]

Heard from Dave and forwarded to your gmail address.

[markjfine]

In case you hadn't seen it: https://www.radioworld.com/tech-and-gear/digital-radio/hubbard-turns-on-an-hd5-audio-channel

[ferrellsl]

Looks like a case of "build it and they will come". It will be an uphill battle getting HD Radio manufacturers to implement HD5 in hardware.

[Whobeu]

Looks like a case of "build it and they will come". It will be an uphill battle getting HD Radio manufacturers to implement HD5 in hardware.

Even if they should start building it today, how many years would it take for in-car radio's and home radio's to be replaced with something newer since I doubt people would be eager to replace their still working radio's just to receive additional streams? I have a now rather old Insignia NS-HD01 Portable HD Radio that receives four HD channels. Works great and I have never really seen anything comparable to it since it was discontinued long ago so I doubt Insignia will start up the productions lines to make a newer version of it. Of course it also goes down the same old rabbit hole of obsolescence of otherwise perfectly good digital hardware. In ten years or so, we will be scrapping any still functioning ATSC 1.0 digital TV's for ATSC 3.0 compatible models (unless one wants to use a converter box). Funny thing is I have an old Meissner 8C FM tuner from around 1950 that had belonged to my late father. It was one of the early "high band" FM radios from when the FCC moved FM to 88-108 MHz. It does not receive stereo obviously but it still works and receives FM radio stations even though it is now 73 or so years old. Unless analog FM is shut down or the band moved (again), it should still keep working as long as the electronics hold up. I wish I could say the same for modern digital hardware.

[ferrellsl]

@Whobeu

I totally agree but I do have to admit that I love the enhanced audio quality of HD Radio and I love being able to view the album art, traffic and weather maps. As a guy who came of age in the 1980s listening to analog broadcasts, HD Radio almost seems like sorcery! LOL!

[markjfine]

I would tend to believe that in-dash manufacturers left the firmware of those receivers open to be updated (much like Ford's Sync system) either by the user using download/USB techniques or at the dealership for a modest labor fee. Shouldn't be any harder than that, really. The real question is if those manufacturers see the return on investment into developing the firmware modifications and upgrade procedures that will determine whether it happens or not. We'll see.

[ferrellsl]

It's sort of a chicken and egg problem. Until consumers start asking for HD5, manufacturers won't invest any time and money into new firmware and with only 1 station in the US broadcasting HD5 and no current HD radios supporting HD5, consumers don't even know it's there to take advantage of it.

[markjfine]

I didn't even know that spec called for more than 4 channels, which is how this thread got started. Perhaps by taking the first step, WWWT tells the other stations, "come on in, the water's fine". Given enough stations do the same, it creates enough of a ripple effect that causes user demand, and consequently a manufacturer response.

TBH I wished that was the case with DRM, which has basically languished for 2 decades.

[ferrellsl]

It would help if WWWT and other stations wanting to implement HD5 would market it and differentiate it from their regular HD radio content. Maybe a more content-rich broadcast to entice users such as offering higher bit rates, commercial free content, or other data such as song lyrics.

[markjfine]

I recently switched to a new ARM-based Mac. After rebuilding the latest I noticed that HD5 no longer works - even against the IQ file. Did not use the -DUSE_NEON switch, as it causes faad2 to fail. However, other than the architecture change there doesn't appear to be any code changes that would cause this... puzzling.

Just making a note of it here and this is not really critical. It appears there still are hardly any stations using HD5-8.

[argilo]

@markjfine Are you sure you're running the add-mp11 branch?

[markjfine]

Lol. I am not. I pulled the main branch. 🤦🏻‍♂️

[argilo]

That would explain it. 😄

Assuming it's still working for WWWT, I should probably open a pull request and get that code merged.

[argilo]

I've opened #297. @markjfine I'd appreciate if you could take that for a spin and make sure that it still decodes WWWT correctly, as well as your other local stations.

[markjfine]

@argilo Works like a champ on the IQ file as well as all live stations... Pulling the right branch (e.g., git pull origin add-mp11 --tags) always helps!

[argilo]

The programming guide for Si468x receiver chips sheds some light on why no receivers want to decode MP11's P4 logical channel:

Property 0x9A00. HD_SERVICE_MODE_CONTROL_MP11_ENABLE

This property Enables MP11 mode support. If MP11 support is disabled using this property the receiver will fall back to MP3 mode of operation when tuned to a station that is transmitting the MP11 subcarriers.

Default: 0x0000

The P4 logical channel is not decoded unless the device opts into it by changing this property. No other service mode gets special treatment like this.

It's still a mystery why there was a need to disable the P4 logical channel. Perhaps some buggy transmitters were causing enough havoc that a workaround became necessary.

[argilo]

Some further progress on MP11:

I extracted the firmware from my Sangean HDT-20 (which uses a Si468x chip to decode HD Radio), disassembled it, found the code that configures the Si468x chip, patched it to set the HD_SERVICE_MODE_CONTROL_MP11_ENABLE property to 0x0001 (enabled), and installed the patched firmware.

After this change, the HDT-20 happily decodes the P4 logical channel from an MP11 test signal generated by gr-nrsc5. This suggests to me that gr-nrsc5's MP11 implementation is correct.

However, the HDT-20 still does not decode the P4 logical channel from WWWT. This suggests to me that its non-standard P4 interleaving is a bug. (Perhaps the same bug that prompted the makers of the Si468x chip to turn off P4 by default?)

I'm not sure what nrsc5 should do about this. Maybe it should attempt to decode P4 both ways, and pick the one that works?

[argilo]

@markjfine Could you send me another recording of WWWT? Unfortunately one of my backups failed and I lost some recordings including WWWT.

One minute or so should be enough. Thanks in advance!

[markjfine]

No problem. Should be up on my site: https://fineware-swl.com/downloads/wwwt_240824223000.iq (size=175,636,480 bytes).

[argilo]

Got it, thanks!

[argilo]

Interestingly, a friend was able to receive WWWT's HD5 with a Sony XDR-F1HD. So it seems there is hardware in the wild that has the nonstandard/broken MP11 interleaving. I might at some point take a crack at having nrsc5 auto-detect the interleaving so that both standard & nonstandard MP11 signals can be received.

[markjfine]

That is very interesting. According to this review by a Northern Virginia FM DXer, the XDR-F1HD was released in 2008. Assuming there were no firmware updates that predates my wife's car radio, which does not see HD5. #weird

[argilo]

2008 is also the year that MP11 was added to the NRSC-5 standard (and MP4 was removed). It could be receivers & transmitters started out with (matching) buggy MP11 implementations, and then the bugs were eventually fixed, but the prevalence of buggy hardware led to MP11 being disabled in many receivers.