What is the coax cable in the wall for?

Quick Answer

The coaxial cable (coax cable for short) in your wall is likely there to provide cable TV and/or broadband internet service throughout your home. Coax cables are used by cable companies to distribute cable TV, cable internet, and cable phone services using a shared network. The coax cables connect your home to the larger cable network, allowing you to plug in TVs, modems, and other devices to access these services.

What Does a Coax Cable Look Like?

A coaxial cable consists of a hollow outer conductor surrounding a single inner conductor. It has a characteristic round or tubular shape with these key components:

– Outer conductor: A tubular layer of braided wire or metallic foil that surrounds the inner conductor. This acts as a shield against electromagnetic interference.

– Inner conductor: A solid metal wire that carries the signal. This is usually copper.

– Insulator: Plastic dielectric material that separates the outer and inner conductors.

– Jacket: Protective plastic sheath covering the outer conductor. Prevents damage and corrosion.

Coax cables come in different sizes, but common ones are about 0.25 inches in diameter. They have connecting ends with terminals to attach to devices or outlets. The cable often has markings on the jacket indicating the manufacturer and cable type.

Where are Coax Cables Located in a Home?

Coax cables are installed in homes in a structured wiring system to deliver signals to different rooms. Here are some of the common locations:

– Living Room: Wall outlets to connect TVs and cable boxes. Often multiple outlets to serve multiple devices.

– Bedrooms: Outlets to connect TVs and internet modems/routers if service is needed in bedrooms.

– Utility Room/Basement: Main entry point where the cable from outside connects to the internal coax wiring. Includes a splitter to separate signals.

– Attic/Crawl Space: Cables routed from the utility room to different floors and rooms. May include amplifiers to boost signals.

– Outside the Home: A main coax cable comes from the nearest cable company utility pole or underground lines and enters the home.

Coax cables inside walls go through small holes drilled in wall studs and floor joists. Cables are attached with clamps for support. The outlets on the wall cover up the hole opening.

What is Coaxial Cable Used For?

Coaxial cable has a few key properties that make it well suited for transmitting video, data, and audio signals:

– Bandwidth: Coax can carry signals at high frequencies up to several gigahertz, supporting up to 1 Gbps bandwidth for digital transmission.

– Shielding: The grounded outer conductor shields against external electromagnetic interference that can disrupt signals.

– Noise rejection: Differential transmission in coax cables reduces internal noise.

– Minimal signal loss: Solid inner conductor and dielectric insulation help maintain strong signal strength over long distances with minimal loss.

– Durability: Tough jacket protects against physical damage while allowing flexibility.

These capabilities enable coax to deliver services like:

– Cable TV: Provides TV channels through coax at frequencies up to 1GHz. Can deliver high definition and 4K channels.

– Cable Internet: Uses coax to provide home broadband internet access at high speeds.

– Cable Phone Service: Digital phone service transmitted through the coax cables.

– Satellite TV: Coax cables connect the satellite dish to receivers inside the home.

– Security Cameras: Analog surveillance cameras often use coax for uninterrupted video feeds across large homes.

– Amateur Radio: Coax used to connect HAM radios to outdoor antennas.

How are Signals Transmitted Through Coax Cables?

Coaxial cable uses high frequency electromagnetic waves to transmit analog and digital signals from a source on one end to devices on the other end.

The signal generator applies an oscillating electric current to the inner conductor. This creates an electromagnetic field around the conductor. The outer conductor then shields the signals from external interference.

The alternating current in the inner conductor causes electrons to oscillate back and forth at very high frequencies, propagating electromagnetic waves along the length of the cable. The signals bounce off the insulator between the inner and outer conductors.

For cable TV, different channels correspond to different frequencies. So channel 2 may use 55 MHz while channel 200 uses 650 MHz. All these signals travel simultaneously through the coax without interfering.

For internet, data is modulated on high frequency carrier signals around 50-860 MHz. Upstream and downstream data is allocated different channels.

Amplifiers placed periodically boost the signals to compensate for attenuation or signal loss as they travel through the coax. Splitters divide the signals to distribute them to multiple outlets and devices.

Key Differences Between Coax and Ethernet Cables

Ethernet cables are also found in homes, often serving as the wired connections to routers for accessing internet. Though both carry data and video, coaxial and Ethernet cables have some key differences:

Factor	Coaxial Cable	Ethernet Cable
Construction	Two conductors – inner and outer separated by insulator	Four twisted pairs of conductors
Topology	Shared broadcast topology	Star bus topology
Shielding	Outer conductor acts as shield	No shielding
Frequency	High frequency – up to GHz range	Lower frequency – up to 100s of MHz
Speed	Up to 1 Gbps for digital	Up to 1-10 Gbps
Distance	Longer runs up to 300 ft	Typically under 100 ft
Noise	Lower noise due to shielding	More noise susceptibility
Security	Shared medium – less secure	Dedicated line per device

Typical Cable TV Coax Connection Setup

Here are the main components in a typical coaxial cable setup to deliver cable TV service throughout a home:

– Cable Drop: The main coaxial line that comes from the nearest cable company utility pole or underground cable line into the house. Uses thick, heavy-duty cable.

– Ground Block: Mounted on exterior wall where cable enters to ground the system and prevent voltage surges from entering.

– Amplifier (optional): Boosts signals if home is large. Often mounted on a pole or side of home.

– Demarcation Point: Transition point between cable company and homeowner equipment.

– Splitter: Splits the signal into multiple paths to deliver to different rooms. 2-way and 3-way splitters common.

– Cables through Walls: Distribute signals to rooms via coaxial cables in walls, attics, crawl spaces.

– Outlets: Wall plates with female coaxial connectors to hook up TVs.

– Cable Box: Required to decode digital signals and pipe content to TVs. Connected via coax.

Proper connectors, terminators, and grounding ensure optimal performance. Installers determine the splitter configuration, cable routing, and outlet locations customized for each home.

How to Install a New Coax Outlet

If your room lacks a coaxial outlet for your TV or internet modem, you can hire an electrician to install a new outlet. Here is an overview of the process:

1. Determine Location: Pick a location for the outlet, ideally near an existing electrical outlet to make running cables easier.

2. Cut Hole: Cut a small hole in the drywall to route the new coaxial cable through. Use a drywall saw.

3. Fish Cable: Run a length of RG-6 coaxial cable from the central splitter location through walls and ceilings to the outlet hole. Use a fish tape tool.

4. Attach Connectors: Attach F-type coaxial connectors to both ends of the new cable.

5. Mount Outlet: Mount a wall plate with female coax jack into the outlet hole. Connect new cable.

6. Connect to Splitter: Connect other end of new cable to an open port on the main coax splitter. May require splitter upgrade.

7. Test Connection: Verify connectivity by connecting a TV and testing signal quality.

Proper coaxial cable routing, shielding, and terminating is key for minimizing interference and signal loss for optimal picture quality. Always hire experienced professionals.

Common Coax Cable Problems

Some common problems that can occur with coaxial cables affecting your cable TV or internet service include:

– Weak or No Signal: Attenuated signal level caused by loose connectors, damaged cables, or splitters installed incorrectly.

– Slow/Unreliable Internet: Damaged coax or poor terminations causing packet loss. Can worsen during wet weather.

– Pixelation and Distorted Picture: Compressed or decompressed video signal from low-quality cables or excessive splits.

– Internet Drops Out: Loose connectors, worn cables, water ingress causing intermittent connection.

– Cable TV Not Available: Disconnected or cut coaxial cable from outdoor lines or rodents.

Many issues can be fixed by visually inspecting cables, connectors, splitters, and re-terminating loose connections. For damaged cables, a certified technician should run new cables as needed. Regular maintenance helps avoid problems.

Conclusion

Coaxial cable remains a versatile and cost-effective way to distribute cable TV, cable internet, and HD video signals around many homes. The shielded cables handle high frequencies well and allow multiple signal transmissions. As fiber optic wiring gains popularity, coax will still continue serving homes for the foreseeable future. Proper installation by certified technicians and periodic terminator checks help ensure your home’s coax network performs reliably for years to come.