Along with your TV antenna and your location, the next critical aspect in your ability to receive free Over-the-Air TV is the presence of obstructions or sources of interference between your antenna and local broadcast towers.
Visible obstructions and/or invisible sources of interference can cause errors in the broadcast TV stream resulting in audio dropouts and/or pixelation and stuttering in the video.
Unlike with analog TV, a digital OTA TV picture won’t degrade slowly into ‘snow’, it will often just stop – something known as the digital cliff.
That’s why obstructions and interference can have a huge impact on the number of channels you’re able to receive and the reliability of those broadcasts.
If you use an OTA DVR like Tablo, obstructions and interference can also cause your recordings to fail.
Common Sources of Over-the-Air TV Obstructions
In general, obstructions are visible impediments affecting the line-of-sight between your local broadcast towers and your Over-the-Air TV antenna.
Common obstructions include:
Mountains & Valleys
If your local broadcast tower is behind a mountain, or you live in a deep valley, obtaining a good OTA TV signal will be problematic as the signal’s line-of-sight will be blocked, or will pass right over your TV antenna.
Trees can also block OTA TV reception, especially in the spring/summer when increased foliage and wind can cause the breakup of Over-the-Air TV video.
If a large concrete office building sits between you and your local broadcast towers, your TV reception may also be blocked. Buildings with ‘mirrored’ exteriors can also create multipath interference as signals are ‘refracted’ or bounced off the shiny surfaces.
Your Home’s Construction Materials
Just like cell phone and satellite radio signals can’t penetrate parking garages, concrete and rebar construction, or mesh stucco walls can block Over-the-Air TV signals.
Over-the-Air antennas should never be placed in basements, or in windows with metallic film, security bars, or mesh as this will obstruct signals. They should also not be placed in attics with a radiant heat barrier or metal roof.
Common Sources of Over-the-Air TV Interference
Just as visible obstructions can impact your Over-the-Air TV signal, invisible sources of interference can also affect your Over-the-Air reception.
Common sources of interference include:
Even if it’s not directly in front of your OTA TV antenna, overhead power lines leading to your house or high-tension lines in your backyard can reflect signals from broadcast towers, decreasing your antenna’s capacity to clearly ‘see’ the signals.
LTE Cell Towers
Traffic from nearby LTE cellular towers can also create invisible interference. Good quality TV tuners (like the ones in Tablo DVRs) and some antennas can have some built-in LTE filtering, but the addition of LTE filter antenna accessories can also help mitigate this.
If your OTA TV signal gets worse at night, try turning off the lights. While newer, good-quality LED lightbulbs certified by the FCC (or Industry Canada) should not cause any interference with your OTA TV signals, older or lower-quality bulbs can create enough radio frequency (RF) interference to block signals.
To a lesser and far more variable degree, weather can affect your OTA TV signal – especially severe fog/rain/snow, and large temperature swings – as the signal reflects off moisture in the atmosphere.
Being aware of potential impacts on your OTA TV signal, and avoiding them when possible is important when switching to antenna TV.