Category: Radio And TV


There appears to be a spike in over-the-air channels producing an annoying and unpleasant greenish looking tint in the picture. The tint can be seen under certain conditions, most notably during black & white programming. The tint is not related to the viewer’s reception or their devices and is usually being produced from the broadcasting station.

When does the green tint occur?

  • During camera pans
  • During fast action scenes
  • During fade ins/outs

Where can it be seen?

  • During black & white shows, commercials, etc.
  • On light black/gray objects
  • On light brown/tan objects
  • Sometimes can be seen on a plan white background

 

The first frame of the tiger appears as it should in black & white. As the video advances over to the next few frames while the camera pans on the tiger, the green tint appears. This is probably due to the channel exceeding it’s given bandwidth.

 

Under minor conditions, the green tint is light and is usually brief. Under extreme conditions, the tint is greener and can be almost constant rather than occasional. You may also notice a quick blur effect in the entire picture from time to time, usually appearing during camera cuts. Another side effect is a thin black bar on the far right side of the screen which is normally not visible unless the picture isn’t being over-scanned.

 

The occasional 2-3 frame blur that is usually seen during camera cuts.

The thin black bar on the right side of the picture, seen when the picture isn’t being over-scanned.

The cause of the green tint is likely being produced by the encoder that the station uses for the affected channel. Perhaps it’s not configured correctly and is allowing more bandwidth than the maximum that’s allowed, possibly corrupting MPEG data. This makes sense as the causes of the green tint described above usually require additional bandwidth in order to keep the picture as minimally compressed as possible.

Because most broadcast stations carry more than one channel (subchannels), the green tint may not affect every channel that the station carries. Common channels affected by the green tint are usually ones in 480i standard definition, but 1080i high definition channels are also affected, though the green tint’s effects are less noticeable.

If you notice a green tint in any broadcast channel and it bothers you, you should contact the station (engineer if possible) and let them know about it. Tell them about the green tint, when & where it occurs and the affected channel. They may tell you to re-scan your TV or adjust your antenna, which is a bunch of nonsense.  The worst possible case is that they won’t do anything about it, but if they get enough complaints from other viewers, then they may look into the problem.

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Thoughts on Digital TV

It has been one year since over-the-air television stations in the United States turned off their analog signals and went completely digital. Since then, there have been improvements in reception from some stations. However, some stations are still having problems getting their digital signal out in places where their analog signal once existed. For others such as low-power and repeater stations, it’s hard to switch to digital since their current analog allotment ranges between channels 52 – 69, (a section that was auctioned off by the FCC)  while the digital allotments (channels 7 – 51) are already being filled up.

A few stations in my area suffer from these scenarios. One station can’t broadcast their digital signal as far as their analog once did because of possible interference to a distant station on that same frequency. Relocating back to their original analog frequency is impossible since that will also cause interference with another distant station, and finding a frequency that won’t interfere with a distant station may cause interference to a local adjacent station.

The other station is a low-power analog station which was recently turned off because its frequency fell in the channel 52 – 69 allotments. They currently have an application for a digital signal on the low VHF band.

The problem is that the FCC made the digital transition too confusing for TV broadcasters. The digital allotment is already crowded, making it hard or impossible for stations wanting to upgrade their transmitter power or go to digital.

In my opinion, this is what that FCC should have done on June 12, 2009. First, the FCC should have kept a few more channels for digital broadcasting. Instead of channels 7 – 51, how about channels 7 – 59. Second, when the June 12, 2009 switch took place, stations broadcasting on channels 7 – 59 should have moved their digital signals back to their original analog frequency. Analog stations that fell between channels 2 – 6 and 60 – 69 should have been relocated to an available digital channel between 7 – 59, possibly a pre-transition channel another station was using. This would have made digital television less confusing, less conflicting, and less crowded.

Note: The FCC does not want stations broadcasting digitally on channels 2 – 6 (low VHF) because they are very sensitive to electro-magnetic interference. Also, low-power stations were not required to turn off their analog signal after the switch to digital.

When buying an antenna, I recommend using an outside TV antenna for receiving the best signal possible. When you buy an outside antenna, buy a combination VHF/UHF antenna. VHF ranges from channels 2 – 13 and UHF ranges from 14 – 69. Although most of your digital channels are located on UHF, few stations broadcast their digital signal on VHF. If you use a UHF only antenna, VHF channels may not come in well and digital channels may break up or not come in at all. Look for a large antenna if you live far away from the TV transmitters. Small antennas are suitable for suburban areas where the TV transmitters are 7 miles or less away from your house.

When installing your antenna, higher is usually better. Have someone help you prop up and install your antenna. Point the UHF antenna towards the TV transmitter you wish to receive.

If you are installing your antenna along with a rotor system, read you rotor’s manual for instructions on calibration. Use www.antennaweb.org for degree information on rotating your antenna towards your local station’s transmitter. If you’re not using a rotor system, use www.antennaweb.org for a map of TV stations in your area and where to point your antenna for the best reception. If you can’t install your antenna outside or you live in a development where outdoor antennas are not allowed, you may install or simply lay your antenna in your attic. Though this may not give you the best signal, I have read reviews that using an outdoor antenna in your attic works well too. If possible, put your antenna in an area of your attic that faces closest to the TV transmitters.

After you mount your antenna, connect the 300-ohm to 75-ohm converter to your antenna. Make sure the twin lead cable going from the antenna to the converter is at least 2 inches away from any aluminum to prevent signal loss. From the converter, connect a high quality coaxial cable with a rating of RG-6. Avoid using RG-59 coaxial in your wiring.  RG-59 is poorly shielded and will result in signal loss. Run the coaxial cable down the mast leaving enough room for your rotor to turn completely around. Although stand-off insulators are not required for coaxial cable, I would recommend using them while running the cable down the mast. If you decide not to use stand-off insulators, use electrical tape or cable ties to secure the cable to the mast.

Avoid long cable runs down into your house as this can slightly reduce signal strength. Once inside your house, cut off any excess cabling and install a type F coaxial connector. Be sure the foil/braided shielding does not make contact with the center wire. Once you’re done, connect the cable directly to your TV or digital tuner. Go though all your channels, verifying that all your channels come in clear and you receive any new channels that you did not receive before. If you are using digital, watch each channel for a few minutes and make sure they don’t drop out or pixilate. If your digital tuner has a signal strength indicator, make sure each channel has a good signal and that the signal strength bar remains in a constant area.

You might want to hook up additional equipment to your antenna as well as well as other TV’s. Please note that a direct connection to your TV/digital tuner provides you the best possible signal. Running your antenna though VCR’s, DVD recorders or surge protectors may slightly reduce your signal. Every time you use a cable splitter on your antenna, you greatly reduce the strength of your signal. If you live in a fringe area, you might want to completely avoid the use of splitters in order to get a decent picture. If you must use splitters, look at its rating. A splitter with a rating of 1-900 MHz will cause less signal loss then a splitter with a rating of 1-800 MHz. A splitter with a 2 GHz rating will provide you minimal signal lost though they are quite expensive. Avoid buying off-brand or “budget” splitters found in dollar stores as they can produce interference. Avoid pre-amps as I never had any luck getting them to work.