How to Increase a Cable Modem Signal to Noise Ratio

Signal-to-noise ratio (SNR) is a gauge of signal strength to and from your cable modem in relation to the background noise. The ideal SNR range is 30 to 50 decibels (dB). High noise or low power levels reduce the SNR and can negatively affect your Internet connectivity, resulting in data loss or slow speeds. Such issues can be caused by problems with wiring or connections but are rectified easily.


Outside Wiring
Step 1

Inspect the cable that runs from the street or pedestal to your house. Breaks in the cable line allow for signal leakage and cause loss of SNR. The rubber casing should be shiny and firm. Replace cables that are cracked, crumbling or show signs of wear.


Step 2

Count connections at the outside splitter. Many houses have an exterior splitter mounted on the side of the building that feeds cable into the various rooms. Each connection to the splitter weakens the overall signal. If there are more than five connections from the splitter, reduce the number of connections or contact the local cable office to have a cable run directly from the pole to the modem.

Check the modem line at the outside splitter. Unscrew the coaxial cable and examine the connector. Ensure that the metal connector is attached firmly to the cable. Also verify that the center conductor (the insulation surrounding the copper wire) is visible and clean. A loose connection may cause the center conductor to shift in varying temperatures, resulting in signal leakage. Replace loose or damaged connectors.


Inside Wiring
Step 1
Remove excess cable running to the modem. Coaxial cable is sold in pre-cut lengths. A common mistake when setting up a modem is to purchase more cable than you need. The longer the cable, the greater the distance the signal must travel. The cable from the wall connection to the modem should be as short as possible.

Step 2
Remove cable splitters. Many people use splitters to allow for a cable modem and television in the same room. Splitters affect signal strength and may decrease the modem's SNR. If multiple connections are necessary, contact the local cable provider to add an additional outlet for the modem.

Step 3
Check for old or damaged cabling. Common culprits are holes caused by nails, staples or other devices used to hold the cable in place. Damaged cable cannot be repaired, it can only be replaced.

Step 4
Check the connection to the modem. Unscrew the cable from the modem and reattach it, ensuring it is firmly affixed to the device.

Contact your local cable provider and request that they measure your signal. It should be possible to determine the SNR to the modem from their offices. If your signal has not improved, it may be necessary for the cable company to send a specialized technician to determine the cause of the issue.


Tips
Outside coaxial cable is typically a heavier grade than inside cable, so make sure to use the proper grade cable when making replacements.
If you do not have the proper equipment to cut or replace cable, contact your local cable provider. Many services are free or have a small fee.

Warnings
 Do not touch cables inside or outside your home if you are not absolutely sure what they are.
 Coaxial cable carries a small current. Do not touch exposed copper wires without the proper safety gear.
 When in doubt, call a professional.

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