Some channels not appearing in channel scan. (They do appear in WMC.)

[cauldwell]

I'm a new NextPVR user, and I'm having trouble getting all of the channels that showed up in Windows Media Center to show up in NextPVR.

For reference, I'm using the Hauppauge WinTV-HVR-2250 in Cambridge (02139, near Boston), with NPVR 2.5.9.

For example, I know that channel WCVB-DT (an HD ABC station) should exist, but it doesn't show up. It used to be channel 5.3 in WMC. On the other hand, WHDH-HD (NBC HD) does exist and show up in NPVR, as (Freq:42 SID:4, which was 7.3 in WMC).

Any idea what's going on? I've been fiddling with this for hours over the past week, but most of the old forum topics here about missing channels are too old, and refer to fields that no longer exist in config.xml.

Log files are attached. One is a QAM scan, and the other is a full ATSC scan.

[sub]

Which log should I be looking in? Are you expecting receive WCVB-DT via ATSC or QAM?

Do you know what frequency it should be on? The first step would be checking if the tuner locks onto that frequency. If it doesn't then NextPVR isn't going to get data from that channel.

Are you sure WMC can still receive that channel? Things can change, like antenna moving, or changes in power levels by the broadcaster.

[johnsonx42]

I'm a little confused... are you connected to digital cable (QAM) or an antenna (ATSC)? Your ATSC scan shows a couple of channels, but extremely few (almost as if you're hooked to cable, and it's acting as a weak antenna picking up a couple of very strong broadcast stations). The QAM scan you posted only goes to channel 19, but it did seem to be detecting a few QAM signals which I really wouldn't expect at all if you were hooked to an antenna.

If you're on cable, which cable company is it? The silicondust database (http://www.silicondust.com/hdhomerun/lin...b/US:02139) shows a variety of cable companies and lineups for your area, at least one of which uses HRC frequencies. If you are on cable, just try full scans with the "Default Cable Frequencies" and "HRC Cable Frequencies" selections.

[cauldwell]

Which log should I be looking in? Are you expecting receive WCVB-DT via ATSC or QAM?

I'm a little confused... are you connected to digital cable (QAM) or an antenna (ATSC)? Your ATSC scan shows a couple of channels, but extremely few (almost as if you're hooked to cable, and it's acting as a weak antenna picking up a couple of very strong broadcast stations).

I posted both logs because I wasn't sure myself. Originally, I thought it should be QAM for sure, since I'm using cable, but I did an ATSC scan just to see if that would help anything. As johnsonx42 mentioned, the ATSC results are probably just anomalous. But I really can see those few ATSC channels in NextPVR, and they're pretty great quality, actually.

I've now attached the log of a full QAM scan, rather than just up to channel 19.

Do you know what frequency it should be on? The first step would be checking if the tuner locks onto that frequency. If it doesn't then NextPVR isn't going to get data from that channel.

WMC used to list WCVB-DT, for example, as channel 5.3. I always thought that that number corresponded with the frequency and station ID that NextPVR lists for QAM channels. I'm not exactly sure what it means for the tuner to "lock on" to a frequency.

If you're on cable, which cable company is it? The silicondust database (http://www.silicondust.com/hdhomerun/lin...b/US:02139) shows a variety of cable companies and lineups for your area, at least one of which uses HRC frequencies.

This one seems like the closest match, but it doesn't list a provider name. The cable "company" is MIT, and they have their own listings which mostly match SiliconDust's.

Are you sure WMC can still receive that channel? Things can change, like antenna moving, or changes in power levels by the broadcaster.

I have no idea whether or not WMC can still receive the channel. I'm now using Windows 8 (Pro, x64), which doesn't include WMC without some risky-seeming hacks until some sort of media add-on is released later this month. In fact, that's why I started using NextPVR.

I suppose it's possible that something on their end could have changed, but it seems all too coincidental that it would happen within a few days of me switching software.

If you are on cable, just try full scans with the "Default Cable Frequencies" and "HRC Cable Frequencies" selections.

Okay, the results are all in the log file attached to this post.

[sub]

According to your MIT listings page WCVB-DT is the only digital channel on CH5, and you logs do show it finding a single digital channel on CH5. There is no names in the broadcast, so nextpvr gives it a name of "unknown 5.4".

[cauldwell]

According to your MIT listings page WCVB-DT is the only digital channel on CH5, and you logs do show it finding a single digital channel on CH5. There is no names in the broadcast, so nextpvr gives it a name of "unknown 5.4".

The programming that's actually airing isn't WCVB-DT, it's "Me-TV", which, according to Wikipedia, is WCVB-SD.

Hmm, maybe somebody here just messed up our cable feed.

It's also weird that WHDH-DT, which is supposed to be on channel 7, shows up on ATSC 42.3 and nowhere else.

[sub]

It's hard to know what to tell you really. It seems like a bit of an oddball network, and without knowing a lot more about it, it's hard to help you work through it.

[cauldwell]

That's fine; I'll keep looking into it myself, and maybe there's someone locally who could answer questions specific to this weird network. At least this is working better than our IPTV network...

Thanks for all of your help! At least I now have most of the channels I should have, rather than the zero I'd have if I were using Windows 8 without NextPVR. =)

[johnsonx42]

While it's certainly not "normal", nothing that I can think of will stop you from using your tuners with both ATSC and QAM channels. In the same vein, while it's certainly not "normal" I don't suppose anything would stop your cable company from transmitting some channels using ATSC 8VSB modulation, with others using QAM64/256 modulation. So maybe those two ATSC channels you're picking up on your cable aren't just accidents...

It's often misunderstood, but what we and the industry call "ATSC" and "QAM" are really both part of the ATSC standard; for over the air broadcast, the ATSC signal is modulated by a method called 8VSB (8-level (3-bit) Vestigial Side Band), while when transmitting over a cable which is less susceptible to interference the ATSC signal is modulated using 64-QAM or 256-QAM (6-bit and 8-bit Quarter Amplitutude Modulation). As you can guess, 6-bit 64QAM can pack twice the amount of data in the same 6Mhz TV channel as 3-bit 8VSB can, and 8-bit 256QAM can pack in another 33% more (but I think needs more error correction codes too). So nothing at all stops an 8VSB signal from being shoved down a cable, even though it would certainly be more efficient to use QAM; indeed the original plan was to use 4-bit 16VSB modulation for digital cable, before the industry decided to use QAM instead.

edit: and now I got myself wondering... are there any 8VSB ATSC signals lurking around on my cable? scanning..... scanning.... scanning.... nope, nary a whisper.

[johnsonx42]

@sub,

I was looking at his MIT digital "HDTV/DTV" lineup, and comparing it to the results of his QAM scan. I noticed that for every frequency NPVR finds exactly one fewer channels than MIT says it should find. MIT says physical channel 2 should have 3 TV channels, NPVR finds 2; physical channel 3 should have 4 TV channels, NPVR finds 3; and so on. That suggest to me that NPVR is in fact missing channels that are there; didn't you have a way to capture more of the stream data to see what might be getting missed (short of doing a full TS capture)?

@cauldwell - your HVR-2250 has two great analog tuners with hardware MPEG-2 compression... have you tried an analog scan? see the Analog Capture Devices section in the thread linked in my signature to enable analog support.