Channels sometimes don't load when directly tuning

[caselogic]

I just setup WMC w/ a Ceton InfiniTV4 on TWC (with a tuning adapter). It works mostly well, but sometimes when I tune to a channel it doesn't load. It says black for a few seconds then says "you need a subscription". However, like 70% of the time if I channel up once or twice then channel back down, it loads within a second.

Can you guys help point me in a direction to troubleshoot? Could this be a WMC configuration issue, or perhaps something with my SDV tuning adapter? When I use the Ceton diagnostic tool, anytime I tell it to check a channel it works (I never get an error from the diagnostic tool).

[barnabas1969]

This is usually a signal problem with the affected channels and/or the signal to the tuning adapter.

Signal strength and quality (Signal to Noise Ratio, SNR, or S/N) can vary from one frequency (channel) to another.

You need to make sure that your signal strength is between -10dB and +10dB on ALL channels on the Ceton. You also need to make sure that the SNR is 35dB or better (34 is OK if the signal strength is near 0dB).

The same goes for the signal strength/quality for the tuning adapter. It needs the Forward Data Channel (FDC or receive) signal strength/quality to be in the same range... +/- 10dB strength, and 35dB SNR (S/N). It also needs the Return Data Channel (RDC or transmit) to be in a range between 25dB to 50dB. The cable companies say that it's OK to go as high as 53-55, but things get dicey above 50.

The FIRST thing to check is to make sure that all coax connections are tight from the point where the cable service enters the house through whatever splitters, and all the way to the tuner and tuning adapter. If tightening connections doesn't help, then see if you can reduce the number of splitters between the service entrance and the tuner/tuning-adapter. This includes reducing the number of splits. For example, if you have a 4-way splitter, but you only need a 2-way splitter... replace the 4-way with a 2-way.

Then, if all of the above fails, call your cable company to fix the problem. They need to understand that the Ceton tuner has a built-in 4-way splitter... so the signal going into the Ceton (read with a cable technician's meter) needs to be 7dB higher than what I quoted above (-3dB to +17dB). But, at the same time, the tuning adapter still needs +/- 10.

[caselogic]

Thanks for the great info! Is there a quick way to check these signal values on a range of channels? Or do I need to select a channel, then go all the way through the settings menu to the tuner diagnostics for every channel?

I went to a channel I was having problems with and when it wasn't able to lock, the SNR was wildly ranging between 5-15 dB and the signal was hovering around +5dBmV. When I switched to a tuner that was successfully locked on the same channel, it was at 34dB signal and -16dBmV.

Those numbers seem a little low compared to what you said, so I might try ditching some splitters leading to my tuner. However, I'm confused why the numbers were all over the place when it couldn't tune vs fairly steady values when it was tuned. Can you help me understand how that works?

[Paw Paw]

I suggest you read the topic about " SNR & Signal Level Protocol w/CC" in this forum. It contains some very good information on troubleshooting low signal levels and SNRs. From what you have described you have a problem with both and it could be that the cable company is not delivering you a quality signal or that you have a wiring problem in your house.

Good Luck

[barnabas1969]

Thanks for the great info! Is there a quick way to check these signal values on a range of channels? Or do I need to select a channel, then go all the way through the settings menu to the tuner diagnostics for every channel?

I went to a channel I was having problems with and when it wasn't able to lock, the SNR was wildly ranging between 5-15 dB and the signal was hovering around +5dBmV. When I switched to a tuner that was successfully locked on the same channel, it was at 34dB signal and -16dBmV.

Those numbers seem a little low compared to what you said, so I might try ditching some splitters leading to my tuner. However, I'm confused why the numbers were all over the place when it couldn't tune vs fairly steady values when it was tuned. Can you help me understand how that works?

The values are only going to be accurate when the tuner is able to lock-in on a channel. The -16dBmV on the one channel is definitely out of spec. SNR of 34dB is OK, but not with a signal that low.

If you want a quick way to get a list of a range of channels, read this thread:
http://experts.windows.com/frms/windows ... 03442.aspx