Dual tuner signal strength problem

[smiffypr]

I have been trying to understand why sometimes recordings are fine, and occasionally very poor.
I have three tuners, a WinTV Nova T stick and a WinTV Nova TD stick (containing two tuners).

In order to get the signal strength displayed on the setting>status window, I deleted the contents of C/program files/NPVR and installed version 1.5.31 (I had version 1.5.36 running previously).

If I record three channels which are on different frequencies (e.g. TV1, TV3 and Prime) I find that two tuners show 100% signal, but one shows a low signal, often 40%.
I have eliminated the aerial cables by swapping them around during recording.

I noticed that it was always tuner 2 on the dual tuner stick which had the low signal. Then I tried changing the priority of the tuners in settings>devices, and found that it wasn't always tuner 2, but the second of the dual tuners to be used.

If it was always the same tuner, I would suspect a hardware issue, but as it is not, it could be a driver issue, or an NPVR issue.
I do have the latest hauppauge drivers installed.

The log shows starting NPVR, going into the guide and setting tree recordings going. The settings>status showed
dev1 path0 100% (dual tuner 1)
dev2 path0 100% (single tuner)
dev1 path1 40% but varying (dual tuner 2)

Any clues from the log as to where the problem lies?

[smiffypr]

I've done some more testing. First I looked at the data rates on the USB connections.
With the three frequencies being recorded, on the USB for dual tuner, data rate averages 6,600,000 B/s,
The single tuner averages 3,300,000 B/s.
With the dual tuner just recording one frequency, data rate averages 3,300,000 B/s, even if it only recording badly with the quality around 40%.
This suggests that the data is OK coming down the USB from the tuners.

Next I tried an amplifier in the aerial signal. This made no difference.

Last I tried changing the priority of the tuners, making the single tuner top priority. With that set-up, the signal qualities were as follows:
dev2 path0 60%-100% (single tuner)
dev1 path0 100% (dual tuner 1)
dev1 path1 60%-100% (dual tuner 2)
However, I then stopped the recordings and started them again, and the quality figures returned to what I was seeing originally (100, 100, 40).

What this suggests is that there is a bottleneck in NRecord.exe (it is running at 1-4% cpu). It must be a strange kind of bottleneck though as the problem doesn't disappear when the 100% recordings are stopped. (The quality figures change to -, 100, 60 and -, -, 60).

Is there anything else I can look at to help identify where the problem is?

[sub]

What this suggests is that there is a bottleneck in NRecord.exe (it is running at 1-4% cpu). It must be a strange kind of bottleneck though as the problem doesn't disappear when the 100% recordings are stopped. (The quality figures change to -, 100, 60 and -, -, 60).

To be honest, I cant follow your logic of why you think this is an NRecord.exe problem. It sounds like a signal or driver problem in your environment with your devices. NRecord.exe isnt going to be effecting your quality figures reported by the tuners.

There is a confirmed issue with the drivers for the Nova-TD stick in New Zealand, at least on Windows 7, which can cause very broken recordings (in all applications). It relates to the guard interval etc used in NZ, which results in us having the highest bitrate DVB-T service in the world, and the Nova-TD drivers arent keeping up. I understand Hauppauge's driver guys are looking into this.

[stustunz]

Just a thought don't you need only 2 tuners to record everything or is it different for dvbt

[smiffypr]

Yes, I'm clutching at straws. I'm pretty sure its not the aerial signal as removing the splitter and just having the signal go to just the dual tuner, or adding an aerial amp, don't change the 40% figure. I'll try contacting hauppauge support.

[smiffypr]

Just a thought don't you need only 2 tuners to record everything or is it different for dvbt

They use three frequencies for the 14 channels I have (666000, 730000 and 762000).

[stustunz]

Ok on satellite there are only 2 freq hence my thought
Bummer
I would be thinkin drives but been USB have you tried different moving them to different inputs
Long shot also

[smiffypr]

I would be thinkin drives but been USB have you tried different moving them to different inputs
Long shot also

I have tried that, front panel USB2, rear USB2, rear USB3, the issue is still the same.

[smiffypr]

I've raised it with hauppauge support, but I thought the first thing they're going to suggest is using WinTV, so I installed that on my laptop and tried recording three programs on three frequencies again. WinTV doesn't give me the choice of which tuner to use first, or display the "signal quality" so I had to go by the end result (the video playback). In this case, it was the third recording to be started which after 7 minutes started displaying the problem, and strangely, this was the one recorded on the single tuner. I'll wait and see what hauppauge support have to say.

[stustunz]

Whats the pc you are recording on?
Does the tuner feel hot?