ETH6 severe pixellation when plug cable modem WAN to router

[tzr916]

Had this ETH6 system up and running stable for months. Newest beta Ceton firmware was working just fine for more than a week then suddenly the picture and sound break up every 3-5 seconds into a complete garbled mess. Happens on live Tv and recordings on PC and extenders.

The problem instantly goes away if I disconnect the ethernet WAN cable that goes from my cable modem to my cisco router (or if I power off the cable mode)! Very strange...


Tried changing:
"Recorded tv" hard drive failure
Ceton Firmware (same symptom with latest beta and original v132)

Rebooted:
ETH6
PC
gigabit switch
cisco router

Tuner signal levels are the same with the cable modem off/on or WAN connected or not:
Temp 31C
Signal -5 to -3 dBmv
SNR 38 dB

[barnabas1969]

Are your tuner and PC plugged into the gigabit switch, or into the router?

[tzr916]

ETH6 (3ft patch), PC (6ft patch), & Extenders (+50ft cat5e) all into the gigabit switch.
One connection from router to the gigabit switch (3ft patch).
One connection from router to modem (3ft patch).
No tuning adapter.
No adds/changes to any hardware.

As a test-
Plugged my laptop directly to modem and got pixellation. Seems to rule out the router/switch...

Down to the modem, 2x 4ft coax, the one splitter...

[erkotz]

This could be an RF issue - what if you plug your modem's Ethernet in, but not coax?

[tzr916]

That was my next test. Pixellation did go away when I disconnected the coax from the modem. Waited about one minute and reconnected the coax. So far no pixellation. Seems like bad coax to the modem. Looks to be solved.

[barnabas1969]

As a test-
Plugged my laptop directly to modem and got pixellation. Seems to rule out the router/switch...

How, exactly, did you plug your laptop directly into the modem and you were still able to access the tuner?

[tzr916]

Watching live Tv on my 55" Tv via HTPC/ETH6, had lots of pixellation.
Unplugged the modem WAN (from the cisco router) => Cleared up all pixellation on my Tv instantly.
Plugged modem WAN directly into my laptop => Pixellation on Tv re-appeared instantly.

[barnabas1969]

So, you're saying that even with the WAN isolated from your LAN... plugging the modem into your laptop resulted in pixelation on the InfiniTV6-ETH? I'm not sure how that's possible. As I understand what you're saying, the laptop and ETH/HTPC were on completely separate networks at this point.

[tzr916]

So, you're saying that even with the WAN isolated from your LAN... plugging the modem into your laptop resulted in pixelation on the InfiniTV6-ETH? ...

That is 100% correct! I was amazed also.

As soon as the modem started grabbing an IP from my laptop the pixellation began.

The final fix was a coax issue to the modem. So RF problem from the modem caused pixellation on the ETH6. Guess the modem shuts off the RF if the WAN is disconnected? dunno...

[barnabas1969]

The modem definitely transmits RF for the up-stream connection... usually at a fairly low frequency. Mine is currently using 23.8MHz, 29.504MHz, 33MHz, and 36.2MHz for the up-stream communication. This will vary with your cable provider and some other factors, but usually will be in the 20-50MHz range.

The CableCARD and TA usually receive down-stream communication (channel maps and authorizations) on a fairly low frequency too. My TA and CableCARD are currently using 75.5MHz.

It is very unlikely that this will interfere with your downstream communications which carry the audio/video signals. The downstream communication for audio/video is usually between 200-800MHz.

[tzr916]

maybe bad ground on the coax connector

[barnabas1969]

Not likely. But, based on my experience with the Echo and the InfiniTV4-PCIe... those devices were so finicky that anything is possible. The Echo would spontaneously reboot if I touched it! Utter crap, in my opinion... but I'm sure some Ceton fanbois will be along shortly to tell me how wrong I am.