Ceton Tuner Strength – Possibly causing Fox to drop out

[PAPutzback]

I have an SNR around 37 and Signal Strength at -11. Is that bad enough to cause frequent (Every 5 – 10) seconds pixelation and freezing?

For WAF i have a splitter feed my Comcast HD tuner and the other leg goes to the CETON Tuner. I guess I could drop a leg but it is strange that it only doesn’t it on Fox. 

My current setup consists of a TAP that feeds the Cable modem and then one leg for cable TV that goes through a 15db amp before going into 1 8 way splitter.

 

[Aaron Ledger]

Does the SNR fluctuate much? Can you correlate a bad video event with a drop in SNR?

Have you viewed the channel with the Comcast receiver and not seen an issue?

Regarding whether an event could happen to just one channel, it is not uncommon. The RF frequencies used in cable systems span a wide range. Different frequencies may be susceptible to interference or quality of the entire chain of infrastructure that brings the cable to your tuner.

[FrankAZ]

Are those levels reported by the Ceton’s tuner diagnostics, or are you calculating them from a measurement elsewhere and your knowledge of the coax network? In themselves those figures are not too terrible though of course 0dBmV would be better.

I have the good fortune to have two Ceton cards, one in each of two machines. One card is a gen 1 from August 2010, the other a gen2 from earlier this year. When I connect them to the very same cable with the same dongle etc I see very different signal levels reported by the two Ceton cards. There is about a 7dB difference. I tried RMA exchanging the gen 2 unit with Ceton and the replacement gen 2 unit showed exactly the same lower signal levels as the first. I mention this because it seems that the Ceton card, or at least the two gen 2 ones and the gen 1 one I have used, report different levels for the same cable. It may be that your measurement of -11dBmV is off, and you are actually seeing something less which would be expected to produce errors.

Have you tried calculating backwards/forwards from the signal levels reported by your Cable Modem or Tuning Adapters to check? In my case I determined that the low signals being reported by the gen 2 Ceton cards were actually not low and I just put up with a reported low signal and enjoy good video. Don’t forget to account for a passive splitter inside the Ceton card which divides the signal at the dongle to each of the 4 tuner modules. That will amount to a 7dBmV drop between the coax cable and the tuners.

My service provider is Cox in Phoenix. They seem to launch all the HD channels at about the same signal level, +/- 2 dBmV so I don’t see a lot of variation from channel to channel. Years ago I did though – it varied horribly by > 8dBmV between adjacent channel numbers, and then I realized that channel numbers were no relation to actual RF frequency. When I compared good vs. bad channels by frequency I found that I was seeing a more periodic rise/fall in signal levels. The culprit turned out to be a bad coax drop to my home. It was buried under some loose stone gravel and people walking on the gravel had caused the stones to puncture the sheath and irrigation water to flood the dielectric. Signal reflections for different frequencies must have been causing constructive or destructive interference at nodes along the cable and my equipment was seeing this as a rising and falling in signal level. You might want to get your cable provider to look into that – it is a simple test they are accustomed to doing and if they find a problem they can replace the drop quickly.

Frank.

[PAPutzback]

Well I removed my backup tuner (The comcast HD box) and my Signal has dropped to -6.3 and SNL to 34.8. So I’ll record whatever is on fox tonight to see if my problem is gone.

What is a safe temp to run the tuners at. Right now I am looking at 59.5 but I think that is about 6 degrees cooler than yesterday since I turned on an additional case fan. But now my case is on the loud side when it isn’t idle. At what temp am I going to hurt the tuner. If it is more than 70 I might as well disable that fan.

 

 

[mikinho]

Per specifications the InfiniTV will work as expected up to 65 C

[PAPutzback]

Then they run pretty hot. They must push the limits in a fanless case. I’m surprised they don’t have heatsinks.

[babgvant]

FWIW, I’ve been running one in the Wesena ITX7 for a couple weeks.  It gets warm (~55-60C) enough that you can notice the increase when touching the case, but I’ve never seen it go over the 65C mark.

[Author]

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