Trouble Scanning for QAM services - HVR1600 - Ubuntu 14.04

Andrew Blank

Moved to General Forums (from Tutorial and setups) as this is a setup question and not instruction**

Greetings,

I'm having trouble getting Tvheadend to find QAM services.

Here's some system details:

OS: Ubuntu Server 14.04 i686
PC Model: Dell Dimension 2400
RAM: 1GB
TV Tuner: Hauppauge HVR-1600 PCI Model 1101 or 1183 (not sure which exactly) feature 3 RF inputs (analog, digital, radio)
http://linuxtv.org/wiki/index.php/Hauppauge_WinTV-HVR-1600

Tvheadend: Stable build installed from here: http://apt.tvheadend.org/stable

I'm using Time Warner Cable in Rochester, NY area and have mapped QAM using Mediaportal in Windows XP on the same machine. The QAMs I've found are documented here:

https://docs.google.com/spreadsheet/ccc?key=0Aiw2GEZqzbM2dGcwZkF5UVlSbzdSMFA1NUt0WXJXaVE&usp=sharing

I tried turning off the Tvheadend service and scanning with W_scan (sudo w_scan -fa -A2 -c US -X >> channels.conf) and this is the output I get:
service_id 1:69000000:QAM_256:1001:1002:1
service_id 2:69000000:QAM_256:1006:1007:2

service_id 3:69000000:QAM_256:1011:1012:3

I thought this might mean a driver issue so I followed the instructions here to build drivers:

http://www.linuxtv.org/wiki/index.php/How_to_Obtain,_Build_and_Install_V4L-DVB_Device_Drivers

I ran into a compile error on those instructions but was able to fix with suggestion from here:
"I managed to convince the build to go forward. It seems to compile fine so far... fingers crossed...
Here's what I did: I opened backports/pr_fmt.patch, remove everything following diff --git a/drivers/media/usb/gspca/dtcs033.c, then ran build again."

source: http://askubuntu.com/questions/449471/compiling-linuxtv-fails-when-appliying-patch

output of W_scan was the same after this build.

In Tvheadend I've manually added the Muxes using the frequencies I found (documented above) and it reports that it's tuning to that frequency but no services found.

Any commands I can run to give more info to a solution please let me know. Thank you!

Andrew Blank

Update: just ran sudo apt-get purge tvheadend and built Tvheadend from source and still having the same issue...

Andrew Blank

Some more info:

I am able to tune QVC identified as QAM 4-2 on frequency 69,000kHz.

Now if my math is correct PBS, which should be on QAM 101-4, should be at 651,000kHz assuming there are 6mHz per QAM.

101 - 4 = 97 * 6,000 = 582,000 + 69,000 = 651,000kHz.

However there are no services found on that frequency but I can still tune it on that QAM on my TV.

Interestingly Mediaportal identified that QAM on frequency 655,250kHz. Tvheadend doesn't find it there either.

Andrew Blank

This is making less and less sense to me. Hopefully someone out there has an idea to help...

So here's my next update. I found a channel TWC uses with a split screen of a few ads for VOD content and a feed from TWC News channel. My TV identifies this as QAM 112-1 and Tvheadend identifies the frequency as 723,000kHz.

Going back to my math trying to figure out what the steps are in frequency between QAMs this is what I have.

112(QAM) - 4(QAM) = 108(QAMs)

723000kHz - 69,000kHz = 654,000kHz / 108(QAMs) = 6055.555555555556(kHz/QAM)

Can someone tell me what I'm doing wrong here?

By the way I have also tried using the pre-built Standard, HRC, & IRC Center frequencies to no avail.

Andrew Blank

Not getting any further but at least I found one thing that makes sense according to this page

http://en.wikipedia.org/wiki/North_American_television_frequencies

the QAM / CDSREF Carrier for Channel 4 is 69,000kHz. On that same page the frequencies and channel numbers I was using in media portal match the STD Video Carrier. So for the QAMs I'm missing I tried adding the QAM / CDSREF Carrier frequency to the multiplexes tab but alas there is still no channels found....

Is there a way to manually add services without scanning the QAMs/Multiplexes?

Thanks again for anyone that can help.

Andrew Blank

Well it took a couple days of leaving it alone but after adding the QAMs mentioned previously the services magically appeared. Any idea why scanning takes so long? Thanks.

Andrew Blank

It's been a long time since this issue and I just wanted to throw out there that recently I went back to working on this and found that, even though the same cable line was attached to the same machine using Media Portal under Windows XP and it tuned QAMs just fine then, there was a signal issue with the cable line with this setup. Connecting this system with TVHeadend more directly to the cable line coming in the house resolved some tuning issues I was having and by the way it's working great with my XBMC on my Raspberry Pi in another room (as well as working great on my android phone and tablet).