How to Test a Cable Signal

By Nichole Liandi

Updated September 28, 2017

Items you will need

  • Small adjustable wrench

  • RF signal meter

Cable television provides a convenient way for a household to enjoy a wide array of television channels. While performance is usually excellent, household systems with a large number of televisions can sometimes suffer from degraded signal quality. The best way to isolate where problems may be occurring is to check cable signal strength throughout the system.

Sketch out a schematic of the cable system in your house. This is especially useful if you have multiple cable outlets and splitters. Leave space by each outlet or connection to record your signal strength readings. The image provides a simple example.

Go to each location and unscrew the cable from its connected device. For example, if you're testing the signal at a television, unscrew the cable from the television. If you're testing the signal strength at a line splitter, unscrew the source end of the cable from the splitter. The cable will always unscrew by turning left. If the cable is too tight to remove with your fingers, use a small adjustable wrench on the connector.


Connect the cable you've just disconnected onto your RF signal strength meter. Turn the meter on and note the reading on your schematic. The signal reading will be a number recorded in dbmV (decibel-millivolts). The controls of a signal meter will vary from model to model and brand to brand, so be sure to consult the manual before using.

Once you've tested your system, look for readings that are outside of the norm. It's normal for the signal strength in your system to be higher before a splitter is employed, but if your signal is significantly lower (more than 3 dBmV) at your televisions, your system may require an amplifier.