What Is a Digital Cable TV Filter?

By Natasha Parks

Take care buying and operating digital cable filters because they have their drawbacks.
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Digital cable filters for televisions are small, electronic components designed to fit between set-top boxes and cable outlets. They are also termed "descramblers." In theory, the filter can receive broadcast signals so you can watch your favorite channels, but it does not send any signals back to the cable company you subscribe to.


The purpose of a digital cable TV filter is that it can receive pay-per-view program signals but block pay per-view-billing signals. Apparently, the cable filter can be bought from companies that offer a service called signal "descrambling" and easily installed in a household. The result is a "free" cable system that offers premium channels, according to reporter Stefanie Olsen at CNET News.

Digital or Analog

There appears to be some misrepresentation in the type of signal and processing cable TV filters use. The filter itself is not digital, but based on analog technology. It has a slimline appearance similar to that of a cable coupler and is no larger than the connector. The analog device is linked into a digital set up when the person fitting it attaches it to the digital set-top box or a nearby signal splitter. Digital Filtering, a company that describes how to use cable filters, advises consumers to reset the cable set-top box regularly and wipe its memory to ensure it works effectively.


Experts in the electronics industry have labeled digital cable TV filters a scam because they claim they cause consumers to waste money and can cause you, as the consumer, to lose out on your cable subscription. Although the blockage of different frequencies is a well-known method for isolating the channel and program a household wishes to watch, using a filter to trick the cable company into thinking no one is accessing their data is inappropriate. This can lead to termination of the consumer contract.


If a technician detects that a filter is being used at a household to illegally descramble signals, and there is enough evidence to prosecute, it potentially can happen. Civil and criminal litigation can be brought against the person who has used the filter to avoid cable charges. It is not illegal to possess a filter or to sell a filter because they are used for many legal purposes, but using one to access cable channels is illegal, as explained by lawyer Aaron Larson at Expert Law.