After Bell TV upgraded the firmware on its 9242 HD PVR last week, Digital Home was bombarded with complaints from Bell customers who said their HD PVR was exhibiting strange behaviour such as randomly changing channels, the PVR recording shows on its own and much more.

After some investigation, Bell TV has reported to Digital Home, the source of the problem is new Sony Bravia televisions which typically have an Ambient light sensor built into them .

The sensor, which monitors light levels in a room and adjusts the televisions brightness levels automatically, is sending infra red (IR) spray around living rooms thereby mimicking random key presses on their Bell TV remotes.

Bell TV is advising Sony Bravia owners who are experiencing problems to turn off the Light Sensor option on their television. Bell says the problem is especially acute when the TV and satellite receiver are in a darkly lit room. Once the light sensor is turned off, the problem goes away.

This incident is simply the latest episode of LCD televisions wreaking havoc with satellite receivers and cable set top boxes. As flat panel television sales have increased in the last three years, Digital Home has witnessed a dramatic rise in the number of readers complaining about new and unusual problems with their cable set top boxes or satellite television receiver.

Typical problems encountered by Digital Home readers include channels on the set top box randomly changing or the set top box remote only working at close range.

After much investigation by Digital Home and its readers, we have learned the problem often results from IR (infra-red) interference or IR spray from your flat panel television. The problem is much more common with LCD televisions because of IR leakage from the LCD backlights.

Simply speaking, the IR spray from IR linkage mimics the signals that are sent out by the remote control resulting in random channel changes or other bizarre behavior.

Unaware that this could be happening, many Digital Home readers have complained that their neighbour is changing the channels on their receiver or that their receiver is faulty! Imagine the sheepish grin on their face after they learn it’s their new expensive flat panel television!

We asked our Digital Forum HDTV guru, 57, what he recommends to stop the problem of IR spray and he gave us the following pieces of advice.
  • Place the cable set top box or satellite receiver further from the HDTV. The farther the set top box is from the television, the less likely you are to encounter problems.
  • Put the receiver in a shielded location so to prevent it from receiving stray IR signals.
  • Change the default picture mode - usually called Vivid or Dynamic - on your flat panel television to something dimmer. By changing to a dimmer mode, the intensity of stray IR signals is typically reduced.

Our guru also tells Digital Home that the problem stops on some makes and models once the TV has been on for a while, so simply waiting a minute or two can sometimes alleviate any problems.

To learn more about this problem and steps you can take to resolve it, check out Digital Home's   "Is your LCD affecting your STB" discussion thread in the Digital Forum.

To read more about the problems affecting Bell TV 9242 HD PVR owners see Digital Home's  9242: Firmware update V184 (Jan 19th, 2010) discussion thread .