Partial/No Lock to CFTO-DT? - Canadian TV, Computing and Home Theatre Forums

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post #1 of 21 (permalink) Old 2019-10-05, 07:43 PM Thread Starter
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Question Partial/No Lock to CFTO-DT?

Hi all,

tl;dr Starting a couple days ago, no longer able to get a lock onto CFTO-DT (9.1).

Have cut the cord a couple years back, but am new to consuming OTA broadcasts through MythTV. A couple days ago, my recordings for late night TV shows on CFTO-DT started failing. As far as I know there were no hardware or software changes made. Yesterday I adjusted the angle of the antenna to be closer to 45deg, so I'd get a stronger reflected signal to CHCJ-DT in Hamilton, but this made no difference in getting a lock onto CFTO-DT.

When I attempt to tune to 9.1, MythTV reports that I should've gotten a lock by now, but there was no lock. A rescan does not bring the channel back. What's odd is that I had no problem tuning to 9.1 prior to a couple days ago. Unfortunately I have no idea where to look to resolve this.

Thanks in advance for any help!
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post #2 of 21 (permalink) Old 2019-10-05, 08:42 PM
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Comes in OK here south of Buffalo with a VHF-Hi Yagi.
So guessing the issue is on your end.
What are you using for an antenna?

DB8E/VHF Yagi rotor FM Bandstop ap-8700 preamp 8way split LG lcd.
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post #3 of 21 (permalink) Old 2019-10-05, 08:49 PM Thread Starter
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AntennasDirect DB4e and a Hauppauge WinTV-QuadHD installed on a machine running MythTV.

Once my other recordings stop, I'll plug the cable back into my TV... something tells me 9.1 will work just fine using the TV tuner, but yes... it definitely seems like something's up on my end.
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post #4 of 21 (permalink) Old 2019-10-05, 09:15 PM
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You are using a UHF only antenna.Make a folded dipole for VHF channel 8 and combine using a UVJ connector and CFTO will come in strong.Are you using the VHF dipole attachment from antennas direct ?

Attic CM 4248 at Buffalo,M4 at Buffalo.VHF yagis at Toronto .
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post #5 of 21 (permalink) Old 2019-10-06, 02:32 AM
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agree that might be all you need, simple dipole.

https://store.antennasdirect.com/VHF-Antenna-Kit.html
couple years ago back when cfto was still on RF9, I had stuck one of those up here,
just to demonstrate that the simple dipole could pull CFTO in most of the time from here. Left it up for about 3 months till I switched antennas around again.

If you install the v4l-utils package, included there is a tool name dvb-fe-tool, which will let you monitor some stats while one of your tuners are tuned to a signal.
Be interesting to see how close to a lock you are, C/N wise. below is the output from a WinTV HD Dual here, which I believe uses the same demod chip as your device, lgdt3306a. eg two demods, instead of your 4 demods. For the lgdt3306a, this is about the minumum required before the signal fails, so I think the 17.8 dB or so indicated is really about 15.5 dB on most of the other tuners that I have. And I have plenty others.

Code:
~]$ dvb-fe-tool -mg -a 2  
FREQUENCY = 183028000
MODULATION = VSB/8
DELIVERY_SYSTEM = ATSC
Timeout(0x3f) Signal= -63.00dBm C/N= 17.84dB
Timeout(0x3f) Signal= -63.00dBm C/N= 17.77dB
Timeout(0x3f) Signal= -63.00dBm C/N= 17.84dB

DB8E/VHF Yagi rotor FM Bandstop ap-8700 preamp 8way split LG lcd.
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post #6 of 21 (permalink) Old 2019-10-06, 10:25 AM Thread Starter
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Thanks for the replies everyone, looks to be a pretty simple solution. The worst part is probably getting up on the ladder again to install it

Some follow ups...

1. I was reading on the other CFTO-DT thread from years ago that CFTO is actually broadcasting on a UHF frequency and then remapped (via PSIP?) to 9.1, so it should work regardless, no?

2. Any thoughts on why it used to work and suddenly does not?
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post #7 of 21 (permalink) Old 2019-10-06, 10:32 AM Thread Starter
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Code:
~$ dvb-fe-tool -mg -a 2
FREQUENCY = 4294967295
MODULATION = VSB/8
DELIVERY_SYSTEM = ATSC
       (0x00) Signal= -111.00dBm C/N= 28.79dB
       (0x00) Signal= -111.00dBm C/N= 28.79dB
       (0x00) Signal= -111.00dBm C/N= 28.79dB
       (0x00) Signal= -111.00dBm C/N= 28.79dB
It was actually the dvb-tools package, by the way. Signal looks good, even though the coax cable is wrapping around the outside of my house.
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post #8 of 21 (permalink) Old 2019-10-06, 12:55 PM
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CFTO in Toronto does not broadcast on UHF, it broadcasts on 183 MHz, which is in the VHF-Hi Band. It may have temporarily used a UHF channel more than 8 years ago, prior to the analog shutdown in 2011 though however not any more.


I agree the C/N looks fine, but the frequency and signal Strength reported by your device looks strange to me, -111 dBm is well below the noise floor. I am not certain the state of the kernel module for your device, as I use a custom kernel that you wouldn't find in the distributions. What distro and kernel are you using?

On another note, some time ago with the help of user 'knight' I posted a little hack to make mythtv report the SNR in dB. It seems the last time I checked, mythtv 0.30 still has the same old bug I saw 9 or 10 years ago, where it reports inaccurate SNR in dB in the OSD / User interface due to a bogus formula they are using in the code...
If interested you would need to apply patch and compile it from source.
Would have to modify this section of code in mythtv/libs/libmythtv/tv_play.cpp and compile.

https://www.digitalhome.ca/forum/31-...-solved-2.html

Again, below is mine this AM.
Code:
 ~]$ dvb-fe-tool -mg -a 2
FREQUENCY = 183028000
MODULATION = VSB/8
DELIVERY_SYSTEM = ATSC
Lock   (0x1f) Signal= -64.00dBm C/N= 20.00dB
Lock   (0x1f) Signal= -64.00dBm C/N= 19.85dB
Lock   (0x1f) Signal= -64.00dBm C/N= 20.00dB
Lock   (0x1f) Signal= -64.00dBm C/N= 20.00dB

DB8E/VHF Yagi rotor FM Bandstop ap-8700 preamp 8way split LG lcd.
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post #9 of 21 (permalink) Old 2019-10-06, 01:08 PM Thread Starter
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You mention that I should be running the dvb-fe-tool while tuning or watching a channel, but I am not sure how to do that, since the results are identical no matter whether the tuner(s) are idle or active.

Nevertheless...

Code:


Not entirely sure why mediatree and hauppauge are in my uname string... hum...
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post #10 of 21 (permalink) Old 2019-10-06, 01:09 PM Thread Starter
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Code:
~$ lsb_release -a
No LSB modules are available.
Distributor ID:	Ubuntu
Description:	Ubuntu 18.04.3 LTS
Release:	18.04
Codename:	bionic

~$ uname -r
Linux media 4.15.0-55201908151420-generic
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post #11 of 21 (permalink) Old 2019-10-06, 01:58 PM
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If you are using the OTA signal to populate the mythtv epg, then mythv will tune your tuners for you to periodically parse the EPG from the OTA signal of each channel.
I don't know if that is how you are configured, but that would be one explanation.
Simple, Just Play a channel in LiveTV.
Then use the dvb-fe-tool to monitor the signal stats for the adapter that you are watching in Live TV.

DB8E/VHF Yagi rotor FM Bandstop ap-8700 preamp 8way split LG lcd.
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post #12 of 21 (permalink) Old 2019-10-06, 04:19 PM
 
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Quote:
Originally Posted by mailtodevnull View Post
AntennasDirect DB4e... it definitely seems like something's up on my end.
Can you test using the tuner in your TV?

I have the same antenna facing WGRZ, plus I am over 30 miles from the CN Tower and RF 8 comes in fine on the backside.
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post #13 of 21 (permalink) Old 2019-10-06, 04:49 PM
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based on the strange frequency indicated in his dvb-fe-tool log, and lack of the frontend status bits being set... s/be (ox1f) if locked, while he has (0x00), I think his device isn't really tuning when he thinks it is.
Another path would be to install another application like kaffeine, and do some testing in there to ensure his device is locking all the frequencies it should be, independent of mythtv. If that looks solid, once that's done he can then chase down his mythtv problem.

DB8E/VHF Yagi rotor FM Bandstop ap-8700 preamp 8way split LG lcd.
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post #14 of 21 (permalink) Old 2019-10-07, 11:26 AM Thread Starter
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majortom -- how would dvb-fe-tool know which tuner to look at, since the card is a quad tuner? I was only tuning to one channel at a time when testing earlier.

Last night was able to get CFTO-DT with heavy distortion (basically unwatchable), but it does mean the antenna can get it even if it's not meant to. However due to how it's mounted, it just isn't pointed directly to it (or 180 degrees from it), and that's probably the issue.

Nevertheless, the VHF retrofit kit is on its way... a whole bunch of the amazon comments specifically talk about this issue (and one even mentions CFTO-DT, heh)
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post #15 of 21 (permalink) Old 2019-10-07, 08:19 PM
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Judging by the USB based WinTV DUAL HD that I have, the two demods show up as separate DVB Adapters. In the snippet below they are /dev/dvb/adapter2, and /dev/dvb/adapter3. adapter0 and adapter1 on my system below are satellite tuners.
I am guessing your system will have 4 adapters, one for each demod.


Code:
 ~]$ ls /dev/dvb
adapter0  adapter1  adapter2  adapter3
So, if I wanted to monitor the stats from adapter 2 I would specify that on the command line. eg:
Meanwhile Adapter 3 shows as not tuned yet.
Code:
~]$ dvb-fe-tool -mg -a2
FREQUENCY = 183028000
MODULATION = VSB/8
DELIVERY_SYSTEM = ATSC
Lock   (0x1f) Signal= -58.00dBm C/N= 19.01dB
Lock   (0x1f) Signal= -59.00dBm C/N= 18.95dB
^C


 ~]$ dvb-fe-tool -mg -a3
FREQUENCY = 0
MODULATION = QPSK
DELIVERY_SYSTEM = ATSC
Timeout(0x20) Signal= -21.00dBm
Timeout(0x20) Signal= -21.00dBm

DB8E/VHF Yagi rotor FM Bandstop ap-8700 preamp 8way split LG lcd.
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