Airports And Ota Tv: A Signal Interference Story

Over-the-air (OTA) TV is a cheap way to access local news, nationally televised sports, and primetime TV. However, it is susceptible to interference from various sources, including natural obstructions like mountains and valleys, as well as human-made structures like large buildings. Even everyday objects in your home, such as LED lights or power tools, can cause issues. For those living near airports, the question of interference is particularly relevant. When planes fly over houses, they can cause multipath interference, reflecting and refracting signals, resulting in temporary picture pixelation or a wobbling effect. This can be mitigated by using a directional antenna, placing it high up, and ensuring it has the narrowest possible beam width.

Multipath interference from aircraft

Multipath interference is a common issue for those living near airports. When an aircraft flies between a TV antenna and a broadcast tower, the signal bounces off the aircraft and reaches the antenna by two different paths. This causes interference and phase shifting of the signal, resulting in a distorted picture. The picture may pixelate, wobble, or become fuzzy, and audio dropouts may occur.

The impact of multipath interference depends on the type of TV broadcast. In analog broadcasts, the picture will wobble, while in digital OTA TV, the picture may stop abruptly, a phenomenon known as the "digital cliff".

To minimise multipath interference, a directional antenna can be used, with the stronger side facing the broadcast tower. Alternatively, placing the antenna higher can help to avoid bounced signals.

Multipath interference is not limited to TV signals. It is also a problem in radio communication, time-of-flight cameras, radar processing, and global positioning systems, where it can cause "ghost targets" and affect the accuracy of location and speed measurements.

Tuner issues

Tuners are responsible for receiving and processing broadcast signals so that they can be displayed on your TV screen. However, issues with tuners can lead to problems in signal reception and processing, resulting in a poor viewing experience.

One common issue with tuners is their inability to handle distorted signals. When an aircraft flies between your antenna and the broadcast tower, the signal can bounce off the moving aircraft, causing multipath interference. This results in the tuner receiving the same transmission multiple times, but with slight time delays between them. As the tuner tries to sort out the distorted signal, you may experience a loss of your digital broadcast or picture pixelation.

To mitigate this issue, you can select an antenna with a narrow beam width in the vertical axis, such as the DB4 or DB8 antenna, which reduces the signal strength of the reflected signal while still receiving the desired signal from the towers.

Another potential issue with tuners is their sensitivity to interference from other electronic devices and wireless signals. For example, LTE and 5G signals from nearby cell phone towers can interfere with OTA TV reception, causing blurry images or loss of sound. To address this, you can select an antenna designed to filter out these frequencies or add a filter that blocks LTE and 5G signals.

Additionally, older or lower-quality LED light bulbs can emit electromagnetic energy and create radio frequency interference that affects OTA TV signals. Upgrading to high-quality LED lights that meet emission standards or adding an EMI filter can resolve this issue.

It is also important to ensure that your TV antenna is positioned correctly and is not blocked by large buildings, trees, or geographical features like mountains and valleys, as these can all impact signal reception and tuner performance.

Finally, issues with tuners can sometimes be resolved by upgrading to a newer model. Older tuners may not have the same capabilities as modern ones, and newer tuners often come with improved features to enhance signal reception and processing, providing a better viewing experience.

Obstructions and interference

Common Obstructions

Obstructions are visible impediments that affect the line-of-sight between your local broadcast towers and your OTA TV antenna. Common obstructions include mountains, valleys, trees, and large buildings. The depth of a valley, the height of mountains and trees, and the size of buildings can all obstruct OTA TV signals. Additionally, buildings with mirrored exteriors can create multipath interference as signals refract or bounce off the shiny surfaces.

The construction materials of your home can also obstruct OTA TV signals. Concrete, rebar, and mesh stucco walls can block OTA TV signals, similar to how they impede cell phone and satellite radio signals. Over-the-air antennas should not be placed in basements, windows with metallic film, security bars, or mesh, as these locations will obstruct signals. Attics with radiant heat barriers or metal roofs are also not suitable for OTA antennas.

Common Sources of Interference

Invisible sources of interference can also impact your OTA TV reception. Overhead power lines, high-tension lines, and nearby LTE cellular towers can reflect signals from broadcast towers, reducing your antenna's ability to receive a clear signal. LTE and 5G signals from cellular towers can overpower television broadcasts, especially when the cell tower is nearby and the broadcast tower is distant.

Older or lower-quality LED light bulbs can create enough radio frequency (RF) interference to block OTA TV signals. Weather conditions, particularly severe fog, rain, snow, and large temperature swings, can also affect OTA TV signals as the signals reflect off moisture in the atmosphere.

Additionally, devices around your home, such as appliances, power tools, and garage door openers, can cause frozen images or intermittent audio issues. Using a low-quality coaxial cable or splitter can also degrade the signal and lead to a snowy or grainy picture.

Airports can also cause interference for OTA TV. When planes fly between the antenna and the broadcast towers, they can reflect the signal, causing multipath interference and resulting in pixelation or a wobbly picture. This issue is more likely to occur if you live within a close range of the airport and the flight path is in the line of sight between your antenna and the broadcast towers.

Antenna placement

The placement of your antenna is critical to achieving good OTA TV reception. Here are some tips to consider for optimal antenna placement:

• Height: The higher you can place the antenna, the better the TV reception will be. Consider installing the antenna on your roof, garage, or attic. If you live in an apartment or condo, a balcony or window-mounted antenna can be a great option.
• Direction: Ensure your antenna is oriented correctly by finding the location of the broadcast towers in your area and directing the antenna towards them. Use a compass for more precise directional adjustments.
• Obstructions: Avoid placing the antenna near metallic objects, electronics, or heavily trafficked areas. Keep the antenna about 5 feet away from metallic objects and electronics to minimise potential signal interference.
• Windows: If possible, place the antenna high up in a window, free from exterior obstructions such as trees, buildings, or billboards. This can help improve signal reception.
• Amplifier: Consider using an amplifier with your antenna to boost the signal. You can purchase a standalone amplifier or choose an antenna with a built-in amplifier.
• Coaxial Cable: Use a high-quality coaxial cable to connect your antenna to your TV or DVR. Avoid using low-quality or thin cables, as they can degrade the signal.
• Experimentation: Sometimes, even small adjustments to the antenna's position can make a significant difference in reception quality. Don't be afraid to experiment with different locations and orientations, especially if you're experiencing multipath interference.

Co-channel interference

To prevent co-channel interference, it is recommended to use a strong, directional antenna. The antenna should be positioned with its stronger side facing the tower transmitting the desired broadcast, while its weaker side should be directed towards the interfering channel. This setup will help mitigate the impact of co-channel interference and improve your viewing experience.

In addition to co-channel interference, other factors can also affect OTA TV reception. For example, multipath interference can occur when an aircraft flies between the antenna and the broadcast tower, causing the signal to reflect off the aircraft and creating a second path to the antenna. This results in the TV picture pixelating or wobbling for a few seconds.

Furthermore, the placement of the antenna is crucial. A choppy picture can be caused by multipath interference, where the broadcast signal bounces off multiple objects before reaching the antenna. Repositioning the antenna higher can help avoid these bounced signals and improve reception.

Additionally, the quality of cables and connectors is important. Using a low-quality coaxial cable or a flat antenna with a thin cable can degrade the signal and lead to reception issues. Upgrading to a high-quality cable and ensuring secure connections can enhance your OTA TV experience.

Frequently asked questions